* [PATCH] drm: add support for VGA arbitration
2009-08-11 5:52 [PATCH] vga: implements VGA arbitration on Linux Dave Airlie
@ 2009-08-11 5:52 ` Dave Airlie
2009-08-11 8:14 ` [PATCH] vga: implements VGA arbitration on Linux Pekka Paalanen
` (3 subsequent siblings)
4 siblings, 0 replies; 17+ messages in thread
From: Dave Airlie @ 2009-08-11 5:52 UTC (permalink / raw)
To: jbarnes; +Cc: linux-kernel, dri-devel, Dave Airlie
From: Dave Airlie <airlied@redhat.com>
this patch has two components:
a) for legacy DRM drivers, we need a hook to enable/disable irqs around
arb when the command/memory is turned off.
b) for KMS drivers we provide a hook/callback to enable/disable VGA decoding.
We don't disable VGA decoding in the single device case, since we believe
some laptops ACPI implementation will react badly.
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
drivers/gpu/drm/drm_irq.c | 27 +++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_dma.c | 20 ++++++++++++++++++++
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_display.c | 23 +++++++++++++++++++++++
drivers/gpu/drm/i915/intel_drv.h | 1 +
drivers/gpu/drm/radeon/r100.c | 14 ++++++++++++++
drivers/gpu/drm/radeon/radeon.h | 2 ++
drivers/gpu/drm/radeon/radeon_asic.h | 9 +++++++++
drivers/gpu/drm/radeon/radeon_device.c | 18 ++++++++++++++++++
include/drm/drmP.h | 3 +++
11 files changed, 119 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index f85aaf2..0a6f0b3 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -37,6 +37,7 @@
#include <linux/interrupt.h> /* For task queue support */
+#include <linux/vgaarb.h>
/**
* Get interrupt from bus id.
*
@@ -171,6 +172,26 @@ err:
}
EXPORT_SYMBOL(drm_vblank_init);
+static void drm_irq_vgaarb_nokms(void *cookie, bool state)
+{
+ struct drm_device *dev = cookie;
+
+ if (dev->driver->vgaarb_irq) {
+ dev->driver->vgaarb_irq(dev, state);
+ return;
+ }
+
+ if (!dev->irq_enabled)
+ return;
+
+ if (state)
+ dev->driver->irq_uninstall(dev);
+ else {
+ dev->driver->irq_preinstall(dev);
+ dev->driver->irq_postinstall(dev);
+ }
+}
+
/**
* Install IRQ handler.
*
@@ -231,6 +252,9 @@ int drm_irq_install(struct drm_device *dev)
return ret;
}
+ if (!drm_core_check_feature(dev, DRIVER_MODESET))
+ vga_client_register(dev->pdev, (void *)dev, drm_irq_vgaarb_nokms, NULL);
+
/* After installing handler */
ret = dev->driver->irq_postinstall(dev);
if (ret < 0) {
@@ -279,6 +303,9 @@ int drm_irq_uninstall(struct drm_device * dev)
DRM_DEBUG("irq=%d\n", dev->pdev->irq);
+ if (!drm_core_check_feature(dev, DRIVER_MODESET))
+ vga_client_register(dev->pdev, NULL, NULL, NULL);
+
dev->driver->irq_uninstall(dev);
free_irq(dev->pdev->irq, dev);
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 50d1f78..9b78c95 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -33,6 +33,7 @@
#include "i915_drm.h"
#include "i915_drv.h"
+#include <linux/vgaarb.h>
#define I915_DRV "i915_drv"
/* Really want an OS-independent resettable timer. Would like to have
@@ -984,6 +985,19 @@ static int i915_probe_agp(struct drm_device *dev, uint32_t *aperture_size,
return 0;
}
+/* true = enable decode, false = disable decoder */
+static unsigned int i915_vga_set_decode(void *cookie, bool state)
+{
+ struct drm_device *dev = cookie;
+
+ intel_modeset_vga_set_state(dev, state);
+ if (state)
+ return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
+ VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+ else
+ return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+}
+
static int i915_load_modeset_init(struct drm_device *dev,
unsigned long prealloc_size,
unsigned long agp_size)
@@ -1029,6 +1043,11 @@ static int i915_load_modeset_init(struct drm_device *dev,
if (ret)
DRM_INFO("failed to find VBIOS tables\n");
+ /* if we have > 1 VGA cards, then disable the radeon VGA resources */
+ ret = vga_client_register(dev->pdev, dev, NULL, i915_vga_set_decode);
+ if (ret)
+ goto destroy_ringbuffer;
+
ret = drm_irq_install(dev);
if (ret)
goto destroy_ringbuffer;
@@ -1289,6 +1308,7 @@ int i915_driver_unload(struct drm_device *dev)
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
drm_irq_uninstall(dev);
+ vga_client_register(dev->pdev, NULL, NULL, NULL);
}
if (dev->pdev->msi_enabled)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7537f57..fd5f6fb 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -750,6 +750,7 @@ static inline void opregion_enable_asle(struct drm_device *dev) { return; }
/* modesetting */
extern void intel_modeset_init(struct drm_device *dev);
extern void intel_modeset_cleanup(struct drm_device *dev);
+extern int intel_modeset_vga_set_state(struct drm_device *dev, bool state);
/**
* Lock test for when it's just for synchronization of ring access.
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 2955083..2c9431b 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -30,6 +30,7 @@
* fb aperture size and the amount of pre-reserved memory.
*/
#define INTEL_GMCH_CTRL 0x52
+#define INTEL_GMCH_VGA_DISABLE (1 << 1)
#define INTEL_GMCH_ENABLED 0x4
#define INTEL_GMCH_MEM_MASK 0x1
#define INTEL_GMCH_MEM_64M 0x1
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d6fce21..7d80b0b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3447,3 +3447,26 @@ struct drm_encoder *intel_best_encoder(struct drm_connector *connector)
return &intel_output->enc;
}
+
+/*
+ * set vga decode state - true == enable VGA decode
+ */
+int intel_modeset_vga_set_state(struct drm_device *dev, bool state)
+{
+ struct pci_dev *bridge_dev;
+ u16 gmch_ctrl;
+
+ bridge_dev = pci_get_bus_and_slot(0, PCI_DEVFN(0, 0));
+ if (!bridge_dev) {
+ DRM_ERROR("Can't disable VGA, no bridge\n");
+ return -1;
+ }
+
+ pci_read_config_word(bridge_dev, INTEL_GMCH_CTRL, &gmch_ctrl);
+ if (state)
+ gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
+ else
+ gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
+ pci_write_config_word(bridge_dev, INTEL_GMCH_CTRL, gmch_ctrl);
+ return 0;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index d6f92ea..7b439ad 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -157,4 +157,5 @@ extern int intel_framebuffer_create(struct drm_device *dev,
struct drm_mode_fb_cmd *mode_cmd,
struct drm_framebuffer **fb,
struct drm_gem_object *obj);
+
#endif /* __INTEL_DRV_H__ */
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index f1ba8ff..16448a4 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -1492,6 +1492,20 @@ void r100_vram_init_sizes(struct radeon_device *rdev)
rdev->mc.real_vram_size = rdev->mc.aper_size;
}
+void r100_vga_set_state(struct radeon_device *rdev, bool state)
+{
+ uint32_t temp;
+
+ temp = RREG32(RADEON_CONFIG_CNTL);
+ if (state == false) {
+ temp &= ~(1<<8);
+ temp |= (1<<9);
+ } else {
+ temp &= ~(1<<9);
+ }
+ WREG32(RADEON_CONFIG_CNTL, temp);
+}
+
void r100_vram_info(struct radeon_device *rdev)
{
r100_vram_get_type(rdev);
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index b1d945b..4565538 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -559,6 +559,7 @@ struct radeon_asic {
int (*init)(struct radeon_device *rdev);
void (*errata)(struct radeon_device *rdev);
void (*vram_info)(struct radeon_device *rdev);
+ void (*vga_set_state)(struct radeon_device *rdev, bool state);
int (*gpu_reset)(struct radeon_device *rdev);
int (*mc_init)(struct radeon_device *rdev);
void (*mc_fini)(struct radeon_device *rdev);
@@ -847,6 +848,7 @@ static inline void radeon_ring_write(struct radeon_device *rdev, uint32_t v)
#define radeon_cs_parse(p) rdev->asic->cs_parse((p))
#define radeon_errata(rdev) (rdev)->asic->errata((rdev))
#define radeon_vram_info(rdev) (rdev)->asic->vram_info((rdev))
+#define radeon_vga_set_state(rdev, state) (rdev)->asic->vga_set_state((rdev), (state))
#define radeon_gpu_reset(rdev) (rdev)->asic->gpu_reset((rdev))
#define radeon_mc_init(rdev) (rdev)->asic->mc_init((rdev))
#define radeon_mc_fini(rdev) (rdev)->asic->mc_fini((rdev))
diff --git a/drivers/gpu/drm/radeon/radeon_asic.h b/drivers/gpu/drm/radeon/radeon_asic.h
index 9a75876..837d606 100644
--- a/drivers/gpu/drm/radeon/radeon_asic.h
+++ b/drivers/gpu/drm/radeon/radeon_asic.h
@@ -46,6 +46,7 @@ uint32_t r100_mm_rreg(struct radeon_device *rdev, uint32_t reg);
void r100_mm_wreg(struct radeon_device *rdev, uint32_t reg, uint32_t v);
void r100_errata(struct radeon_device *rdev);
void r100_vram_info(struct radeon_device *rdev);
+void r100_vga_set_state(struct radeon_device *rdev, bool state);
int r100_gpu_reset(struct radeon_device *rdev);
int r100_mc_init(struct radeon_device *rdev);
void r100_mc_fini(struct radeon_device *rdev);
@@ -81,6 +82,7 @@ static struct radeon_asic r100_asic = {
.init = &r100_init,
.errata = &r100_errata,
.vram_info = &r100_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &r100_gpu_reset,
.mc_init = &r100_mc_init,
.mc_fini = &r100_mc_fini,
@@ -141,6 +143,7 @@ static struct radeon_asic r300_asic = {
.init = &r300_init,
.errata = &r300_errata,
.vram_info = &r300_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &r300_gpu_reset,
.mc_init = &r300_mc_init,
.mc_fini = &r300_mc_fini,
@@ -181,6 +184,7 @@ static struct radeon_asic r420_asic = {
.init = &r300_init,
.errata = &r420_errata,
.vram_info = &r420_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &r300_gpu_reset,
.mc_init = &r420_mc_init,
.mc_fini = &r420_mc_fini,
@@ -228,6 +232,7 @@ static struct radeon_asic rs400_asic = {
.init = &r300_init,
.errata = &rs400_errata,
.vram_info = &rs400_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &r300_gpu_reset,
.mc_init = &rs400_mc_init,
.mc_fini = &rs400_mc_fini,
@@ -277,6 +282,7 @@ static struct radeon_asic rs600_asic = {
.init = &r300_init,
.errata = &rs600_errata,
.vram_info = &rs600_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &r300_gpu_reset,
.mc_init = &rs600_mc_init,
.mc_fini = &rs600_mc_fini,
@@ -319,6 +325,7 @@ static struct radeon_asic rs690_asic = {
.init = &r300_init,
.errata = &rs690_errata,
.vram_info = &rs690_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &r300_gpu_reset,
.mc_init = &rs690_mc_init,
.mc_fini = &rs690_mc_fini,
@@ -368,6 +375,7 @@ static struct radeon_asic rv515_asic = {
.init = &rv515_init,
.errata = &rv515_errata,
.vram_info = &rv515_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &rv515_gpu_reset,
.mc_init = &rv515_mc_init,
.mc_fini = &rv515_mc_fini,
@@ -410,6 +418,7 @@ static struct radeon_asic r520_asic = {
.init = &rv515_init,
.errata = &r520_errata,
.vram_info = &r520_vram_info,
+ .vga_set_state = &r100_vga_set_state,
.gpu_reset = &rv515_gpu_reset,
.mc_init = &r520_mc_init,
.mc_fini = &r520_mc_fini,
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 9ff6dcb..c6f03c2 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -29,6 +29,7 @@
#include <drm/drmP.h>
#include <drm/drm_crtc_helper.h>
#include <drm/radeon_drm.h>
+#include <linux/vgaarb.h>
#include "radeon_reg.h"
#include "radeon.h"
#include "radeon_asic.h"
@@ -446,7 +447,18 @@ void radeon_combios_fini(struct radeon_device *rdev)
int radeon_modeset_init(struct radeon_device *rdev);
void radeon_modeset_fini(struct radeon_device *rdev);
+/* if we get transitioned to only one device, tak VGA back */
+static unsigned int radeon_vga_set_decode(void *cookie, bool state)
+{
+ struct radeon_device *rdev = cookie;
+ radeon_vga_set_state(rdev, state);
+ if (state)
+ return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
+ VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+ else
+ return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+}
/*
* Radeon device.
*/
@@ -535,6 +547,11 @@ int radeon_device_init(struct radeon_device *rdev,
/* Initialize surface registers */
radeon_surface_init(rdev);
+ /* if we have > 1 VGA cards, then disable the radeon VGA resources */
+ ret = vga_client_register(rdev->pdev, rdev, NULL, radeon_vga_set_decode);
+ if (ret)
+ return -EINVAL;
+
/* TODO: disable VGA need to use VGA request */
/* BIOS*/
if (!radeon_get_bios(rdev)) {
@@ -669,6 +686,7 @@ void radeon_device_fini(struct radeon_device *rdev)
radeon_agp_fini(rdev);
#endif
radeon_irq_kms_fini(rdev);
+ vga_client_register(rdev->pdev, NULL, NULL, NULL);
radeon_fence_driver_fini(rdev);
radeon_clocks_fini(rdev);
if (rdev->is_atom_bios) {
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 45b67d9..95106c7 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -786,6 +786,9 @@ struct drm_driver {
int (*gem_init_object) (struct drm_gem_object *obj);
void (*gem_free_object) (struct drm_gem_object *obj);
+ /* vga arb irq handler */
+ void (*vgaarb_irq)(struct drm_device *dev, bool state);
+
/* Driver private ops for this object */
struct vm_operations_struct *gem_vm_ops;
--
1.6.0.6
^ permalink raw reply related [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 5:52 [PATCH] vga: implements VGA arbitration on Linux Dave Airlie
2009-08-11 5:52 ` [PATCH] drm: add support for VGA arbitration Dave Airlie
@ 2009-08-11 8:14 ` Pekka Paalanen
2009-08-11 23:17 ` Jesse Barnes
` (2 subsequent siblings)
4 siblings, 0 replies; 17+ messages in thread
From: Pekka Paalanen @ 2009-08-11 8:14 UTC (permalink / raw)
To: Dave Airlie; +Cc: jbarnes, Dave Airlie, linux-kernel, dri-devel
Hi,
some minor comments below.
On Tue, 11 Aug 2009 15:52:06 +1000
Dave Airlie <airlied@gmail.com> wrote:
> From: Tiago Vignatti <tiago.vignatti@nokia.com>
>
> Background:
> Graphic devices are accessed through ranges in I/O or memory space. While most
> modern devices allow relocation of such ranges, some "Legacy" VGA devices
> implemented on PCI will typically have the same "hard-decoded" addresses as
> they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994
> Standard for Boot (Initialization Configuration) Firmware Revision 2.1"
> Section 7, Legacy Devices.
>
> The Resource Access Control (RAC) module inside the X server currently does
> the task of arbitration when more than one legacy device co-exists on the same
> machine. But the problem happens when these devices are trying to be accessed
> by different userspace clients (e.g. two server in parallel). Their address
> assignments conflict. Therefore an arbitration scheme _outside_ of the X
> server is needed to control the sharing of these resources. This document
> introduces the operation of the VGA arbiter implemented for Linux kernel.
>
> Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> Signed-off-by: Dave Airlie <airlied@redhat.com>
> ---
> drivers/gpu/Makefile | 2 +-
> drivers/gpu/vga/Kconfig | 10 +
> drivers/gpu/vga/Makefile | 1 +
> drivers/gpu/vga/vgaarb.c | 1206 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/pci/pci.c | 44 ++
> drivers/video/Kconfig | 2 +
> include/linux/pci.h | 2 +
> include/linux/vgaarb.h | 195 ++++++++
> 8 files changed, 1461 insertions(+), 1 deletions(-)
> create mode 100644 drivers/gpu/vga/Kconfig
> create mode 100644 drivers/gpu/vga/Makefile
> create mode 100644 drivers/gpu/vga/vgaarb.c
> create mode 100644 include/linux/vgaarb.h
>
> diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
> index de566cf..30879df 100644
> --- a/drivers/gpu/Makefile
> +++ b/drivers/gpu/Makefile
> @@ -1 +1 @@
> -obj-y += drm/
> +obj-y += drm/ vga/
> diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
> new file mode 100644
> index 0000000..790e675
> --- /dev/null
> +++ b/drivers/gpu/vga/Kconfig
> @@ -0,0 +1,10 @@
> +config VGA_ARB
> + bool "VGA Arbitration" if EMBEDDED
> + default y
> + depends on PCI
> + help
> + Some "legacy" VGA devices implemented on PCI typically have the same
> + hard-decoded addresses as they did on ISA. When multiple PCI devices
> + are accessed at same time they need some kind of coordination. Please
> + see Documentation/vgaarbiter.txt for more details. Select this to
> + enable VGA arbiter.
The file Documentation/vgaarbiter.txt does not exist.
> diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
> new file mode 100644
> index 0000000..7cc8c1e
> --- /dev/null
> +++ b/drivers/gpu/vga/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_VGA_ARB) += vgaarb.o
> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> new file mode 100644
> index 0000000..199138f
> --- /dev/null
> +++ b/drivers/gpu/vga/vgaarb.c
> @@ -0,0 +1,1206 @@
> +/*
> + * vgaarb.c
> + *
> + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
> + *
> + * Implements the VGA arbitration. For details refer to
> + * Documentation/vgaarbiter.txt
Another reference to vgaarbiter.txt.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +#include <linux/errno.h>
> +#include <linux/init.h>
> +#include <linux/list.h>
> +#include <linux/sched.h>
> +#include <linux/wait.h>
> +#include <linux/spinlock.h>
> +#include <linux/poll.h>
> +#include <linux/miscdevice.h>
> +
> +#include <linux/uaccess.h>
> +
> +#include <linux/vgaarb.h>
> +
> +static void vga_arbiter_notify_clients(void);
> +/*
> + * We keep a list of all vga devices in the system to speed
> + * up the various operations of the arbiter
> + */
> +struct vga_device {
> + struct list_head list;
> + struct pci_dev *pdev;
> + unsigned int decodes; /* what does it decodes */
> + unsigned int owns; /* what does it owns */
> + unsigned int locks; /* what does it locks */
> + unsigned int io_lock_cnt; /* legacy IO lock count */
> + unsigned int mem_lock_cnt; /* legacy MEM lock count */
> + unsigned int io_norm_cnt; /* normal IO count */
> + unsigned int mem_norm_cnt; /* normal MEM count */
> +
> + /* allow IRQ enable/disable hook */
> + void *cookie;
> + void (*irq_set_state)(void *cookie, bool enable);
> + unsigned int (*set_vga_decode)(void *cookie, bool decode);
> +};
> +
> +static LIST_HEAD(vga_list);
> +static int vga_count, vga_decode_count;
> +static bool vga_arbiter_used;
> +static DEFINE_SPINLOCK(vga_lock);
> +static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
> +
> +
> +static const char *vga_iostate_to_str(unsigned int iostate)
> +{
> + /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
> + iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + switch (iostate) {
> + case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
> + return "io+mem";
> + case VGA_RSRC_LEGACY_IO:
> + return "io";
> + case VGA_RSRC_LEGACY_MEM:
> + return "mem";
> + }
> + return "none";
> +}
> +
> +static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
> +{
> + /* we could in theory hand out locks on IO and mem
> + * separately to userspace but it can cause deadlocks */
> + if (strncmp(buf, "none", 4) == 0) {
> + *io_state = VGA_RSRC_NONE;
> + return 1;
> + }
> +
> + /* XXX We're not chekcing the str_size! */
> + if (strncmp(buf, "io+mem", 6) == 0)
> + goto both;
> + else if (strncmp(buf, "io", 2) == 0)
> + goto both;
> + else if (strncmp(buf, "mem", 3) == 0)
> + goto both;
> + return 0;
> +both:
> + *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + return 1;
> +}
> +
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +/* this is only used a cookie - it should not be dereferenced */
> +static struct pci_dev *vga_default;
> +#endif
> +
> +static void vga_arb_device_card_gone(struct pci_dev *pdev);
> +
> +/* Find somebody in our list */
> +static struct vga_device *vgadev_find(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> +
> + list_for_each_entry(vgadev, &vga_list, list)
> + if (pdev == vgadev->pdev)
> + return vgadev;
> + return NULL;
> +}
> +
> +/* Returns the default VGA device (vgacon's babe) */
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +struct pci_dev *vga_default_device(void)
> +{
> + return vga_default;
> +}
> +#endif
> +
> +static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
> +{
> + if (vgadev->irq_set_state)
> + vgadev->irq_set_state(vgadev->cookie, state);
> +}
> +
> +
> +/* If we don't ever use VGA arb we should avoid
> + turning off anything anywhere due to old X servers getting
> + confused about the boot device not being VGA */
> +static void vga_check_first_use(void)
> +{
> + /* we should inform all GPUs in the system that
> + * VGA arb has occured and to try and disable resources
> + * if they can */
> + if (!vga_arbiter_used) {
> + vga_arbiter_used = true;
> + vga_arbiter_notify_clients();
> + }
> +}
> +
> +static struct vga_device *__vga_tryget(struct vga_device *vgadev,
> + unsigned int rsrc)
> +{
> + unsigned int wants, legacy_wants, match;
> + struct vga_device *conflict;
> + unsigned int pci_bits;
> + /* Account for "normal" resources to lock. If we decode the legacy,
> + * counterpart, we need to request it as well
> + */
> + if ((rsrc & VGA_RSRC_NORMAL_IO) &&
> + (vgadev->decodes & VGA_RSRC_LEGACY_IO))
> + rsrc |= VGA_RSRC_LEGACY_IO;
> + if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
> + (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
> + rsrc |= VGA_RSRC_LEGACY_MEM;
> +
> + pr_devel("%s: %d\n", __func__, rsrc);
> + pr_devel("%s: owns: %d\n", __func__, vgadev->owns);
> +
> + /* Check what resources we need to acquire */
> + wants = rsrc & ~vgadev->owns;
> +
> + /* We already own everything, just mark locked & bye bye */
> + if (wants == 0)
> + goto lock_them;
> +
> + /* We don't need to request a legacy resource, we just enable
> + * appropriate decoding and go
> + */
Does this comment mean "We don't need to request a legacy resource,
therefore ..." or "If a legacy resource is not required, ..."?
Well, it gets clear when I read and think about the code, but
the comment got me confused for a moment.
> + legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
> + if (legacy_wants == 0)
> + goto enable_them;
> +
> + /* Ok, we don't, let's find out how we need to kick off */
We don't what?
> + list_for_each_entry(conflict, &vga_list, list) {
> + unsigned int lwants = legacy_wants;
> + unsigned int change_bridge = 0;
> +
> + /* Don't conflict with myself */
> + if (vgadev == conflict)
> + continue;
> +
> + /* Check if the architecture allows a conflict between those
> + * 2 devices or if they are on separate domains
> + */
> + if (!vga_conflicts(vgadev->pdev, conflict->pdev))
> + continue;
> +
> + /* We have a possible conflict. before we go further, we must
> + * check if we sit on the same bus as the conflicting device.
> + * if we don't, then we must tie both IO and MEM resources
> + * together since there is only a single bit controlling
> + * VGA forwarding on P2P bridges
> + */
> + if (vgadev->pdev->bus != conflict->pdev->bus) {
> + change_bridge = 1;
> + lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + }
> +
> + /* Check if the guy has a lock on the resource. If he does,
> + * return the conflicting entry
> + */
> + if (conflict->locks & lwants)
> + return conflict;
> +
> + /* Ok, now check if he owns the resource we want. We don't need
> + * to check "decodes" since it should be impossible to own
> + * own legacy resources you don't decode unless I have a bug
> + * in this code...
> + */
> + WARN_ON(conflict->owns & ~conflict->decodes);
> + match = lwants & conflict->owns;
> + if (!match)
> + continue;
> +
> + /* looks like he doesn't have a lock, we can steal
> + * them from him
> + */
> + vga_irq_set_state(conflict, false);
> +
> + pci_bits = 0;
> + if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> + pci_bits |= PCI_COMMAND_MEMORY;
> + if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> + pci_bits |= PCI_COMMAND_IO;
> +
> + pci_set_vga_state(conflict->pdev, false, pci_bits,
> + change_bridge);
> + conflict->owns &= ~lwants;
> + /* If he also owned non-legacy, that is no longer the case */
> + if (lwants & VGA_RSRC_LEGACY_MEM)
> + conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
> + if (lwants & VGA_RSRC_LEGACY_IO)
> + conflict->owns &= ~VGA_RSRC_NORMAL_IO;
> + }
> +
> +enable_them:
> + /* ok dude, we got it, everybody conflicting has been disabled, let's
> + * enable us. Make sure we don't mark a bit in "owns" that we don't
> + * also have in "decodes". We can lock resources we don't decode but
> + * not own them.
> + */
> + pci_bits = 0;
> + if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> + pci_bits |= PCI_COMMAND_MEMORY;
> + if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> + pci_bits |= PCI_COMMAND_IO;
> + pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
> +
> + vga_irq_set_state(vgadev, true);
> + vgadev->owns |= (wants & vgadev->decodes);
> +lock_them:
> + vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
> + if (rsrc & VGA_RSRC_LEGACY_IO)
> + vgadev->io_lock_cnt++;
> + if (rsrc & VGA_RSRC_LEGACY_MEM)
> + vgadev->mem_lock_cnt++;
> + if (rsrc & VGA_RSRC_NORMAL_IO)
> + vgadev->io_norm_cnt++;
> + if (rsrc & VGA_RSRC_NORMAL_MEM)
> + vgadev->mem_norm_cnt++;
> +
> + return NULL;
> +}
> +
> +static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
> +{
> + unsigned int old_locks = vgadev->locks;
> +
> + pr_devel("%s\n", __func__);
> +
> + /* Update our counters, and account for equivalent legacy resources
> + * if we decode them
> + */
> + if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
> + vgadev->io_norm_cnt--;
> + if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
> + rsrc |= VGA_RSRC_LEGACY_IO;
> + }
> + if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
> + vgadev->mem_norm_cnt--;
> + if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
> + rsrc |= VGA_RSRC_LEGACY_MEM;
> + }
> + if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
> + vgadev->io_lock_cnt--;
> + if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
> + vgadev->mem_lock_cnt--;
> +
> + /* Just clear lock bits, we do lazy operations so we don't really
> + * have to bother about anything else at this point
> + */
> + if (vgadev->io_lock_cnt == 0)
> + vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
> + if (vgadev->mem_lock_cnt == 0)
> + vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
> +
> + /* Kick the wait queue in case somebody was waiting if we actually
> + * released something
> + */
> + if (old_locks != vgadev->locks)
> + wake_up_all(&vga_wait_queue);
> +}
> +
> +int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
> +{
> + struct vga_device *vgadev, *conflict;
> + unsigned long flags;
> + wait_queue_t wait;
> + int rc = 0;
> +
> + vga_check_first_use();
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return 0;
> +
> + for (;;) {
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + spin_unlock_irqrestore(&vga_lock, flags);
> + rc = -ENODEV;
> + break;
> + }
> + conflict = __vga_tryget(vgadev, rsrc);
> + spin_unlock_irqrestore(&vga_lock, flags);
> + if (conflict == NULL)
> + break;
> +
> +
> + /* We have a conflict, we wait until somebody kicks the
> + * work queue. Currently we have one work queue that we
> + * kick each time some resources are released, but it would
> + * be fairly easy to have a per device one so that we only
> + * need to attach to the conflicting device
> + */
> + init_waitqueue_entry(&wait, current);
> + add_wait_queue(&vga_wait_queue, &wait);
> + set_current_state(interruptible ?
> + TASK_INTERRUPTIBLE :
> + TASK_UNINTERRUPTIBLE);
> + if (signal_pending(current)) {
> + rc = -EINTR;
> + break;
> + }
> + schedule();
> + remove_wait_queue(&vga_wait_queue, &wait);
> + set_current_state(TASK_RUNNING);
> + }
> + return rc;
> +}
> +EXPORT_SYMBOL(vga_get);
> +
> +int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + int rc = 0;
> +
> + vga_check_first_use();
> +
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return 0;
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + rc = -ENODEV;
> + goto bail;
> + }
> + if (__vga_tryget(vgadev, rsrc))
> + rc = -EBUSY;
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return rc;
> +}
> +EXPORT_SYMBOL(vga_tryget);
> +
> +void vga_put(struct pci_dev *pdev, unsigned int rsrc)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return;
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL)
> + goto bail;
> + __vga_put(vgadev, rsrc);
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +EXPORT_SYMBOL(vga_put);
> +
> +/*
> + * Currently, we assume that the "initial" setup of the system is
> + * not sane, that is we come up with conflicting devices and let
> + * the arbiter's client decides if devices decodes or not legacy
> + * things.
> + */
> +static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + struct pci_bus *bus;
> + struct pci_dev *bridge;
> + u16 cmd;
> +
> + /* Only deal with VGA class devices */
> + if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> + return false;
> +
> + /* Allocate structure */
> + vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
> + if (vgadev == NULL) {
> + pr_err("vgaarb: failed to allocate pci device\n");
> + /* What to do on allocation failure ? For now, let's
> + * just do nothing, I'm not sure there is anything saner
> + * to be done
> + */
> + return false;
> + }
> +
> + memset(vgadev, 0, sizeof(*vgadev));
> +
> + /* Take lock & check for duplicates */
> + spin_lock_irqsave(&vga_lock, flags);
> + if (vgadev_find(pdev) != NULL) {
> + BUG_ON(1);
> + goto fail;
> + }
> + vgadev->pdev = pdev;
> +
> + /* By default, assume we decode everything */
> + vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
> + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
> +
> + /* by default mark it as decoding */
> + vga_decode_count++;
> + /* Mark that we "own" resources based on our enables, we will
> + * clear that below if the bridge isn't forwarding
> + */
> + pci_read_config_word(pdev, PCI_COMMAND, &cmd);
> + if (cmd & PCI_COMMAND_IO)
> + vgadev->owns |= VGA_RSRC_LEGACY_IO;
> + if (cmd & PCI_COMMAND_MEMORY)
> + vgadev->owns |= VGA_RSRC_LEGACY_MEM;
> +
> + /* Check if VGA cycles can get down to us */
> + bus = pdev->bus;
> + while (bus) {
> + bridge = bus->self;
> + if (bridge) {
> + u16 l;
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &l);
> + if (!(l & PCI_BRIDGE_CTL_VGA)) {
> + vgadev->owns = 0;
> + break;
> + }
> + }
> + bus = bus->parent;
> + }
> +
> + /* Deal with VGA default device. Use first enabled one
> + * by default if arch doesn't have it's own hook
> + */
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> + if (vga_default == NULL &&
> + ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
> + vga_default = pci_dev_get(pdev);
> +#endif
> +
> + /* Add to the list */
> + list_add(&vgadev->list, &vga_list);
> + vga_count++;
> + pr_info("vgaarb: device added: PCI:%s,decodes=%s,owns=%s,locks=%s\n",
> + pci_name(pdev),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns),
> + vga_iostate_to_str(vgadev->locks));
> +
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return true;
> +fail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + kfree(vgadev);
> + return false;
> +}
> +
> +static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + bool ret = true;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + ret = false;
> + goto bail;
> + }
> +
> + if (vga_default == pdev) {
> + pci_dev_put(vga_default);
> + vga_default = NULL;
> + }
> +
> + if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
> + vga_decode_count--;
> +
> + /* Remove entry from list */
> + list_del(&vgadev->list);
> + vga_count--;
> + /* Notify userland driver that the device is gone so it discards
> + * it's copies of the pci_dev pointer
> + */
> + vga_arb_device_card_gone(pdev);
> +
> + /* Wake up all possible waiters */
> + wake_up_all(&vga_wait_queue);
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + kfree(vgadev);
> + return ret;
> +}
> +
> +/* this is called with the lock */
> +static inline void vga_update_device_decodes(struct vga_device *vgadev,
> + int new_decodes)
> +{
> + int old_decodes;
> + struct vga_device *new_vgadev, *conflict;
> +
> + old_decodes = vgadev->decodes;
> + vgadev->decodes = new_decodes;
> +
> + pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
> + pci_name(vgadev->pdev),
> + vga_iostate_to_str(old_decodes),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns));
> +
> +
> + /* if we own the decodes we should move them along to
> + another card */
> + if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
> + /* set us to own nothing */
> + vgadev->owns &= ~old_decodes;
> + list_for_each_entry(new_vgadev, &vga_list, list) {
> + if ((new_vgadev != vgadev) &&
> + (new_vgadev->decodes & VGA_RSRC_LEGACY_MASK)) {
> + pr_info("vgaarb: transferring owner from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev), pci_name(new_vgadev->pdev));
> + conflict = __vga_tryget(new_vgadev, VGA_RSRC_LEGACY_MASK);
> + if (!conflict)
> + __vga_put(new_vgadev, VGA_RSRC_LEGACY_MASK);
> + break;
> + }
> + }
> + }
> +
> + /* change decodes counter */
> + if (old_decodes != new_decodes) {
> + if (new_decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
> + vga_decode_count++;
> + else
> + vga_decode_count--;
> + }
> +}
> +
> +void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes, bool userspace)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + decodes &= VGA_RSRC_LEGACY_MASK;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL)
> + goto bail;
> +
> + /* don't let userspace futz with kernel driver decodes */
> + if (userspace && vgadev->set_vga_decode)
> + goto bail;
> +
> + /* update the device decodes + counter */
> + vga_update_device_decodes(vgadev, decodes);
> +
> + /* XXX if somebody is going from "doesn't decode" to "decodes" state
> + * here, additional care must be taken as we may have pending owner
> + * ship of non-legacy region ...
> + */
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +
> +void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
> +{
> + __vga_set_legacy_decoding(pdev, decodes, false);
> +}
> +EXPORT_SYMBOL(vga_set_legacy_decoding);
> +
> +/* return number of active VGA devices */
That comment is incorrect.
> +/* call with NULL to unregister */
> +int vga_client_register(struct pci_dev *pdev, void *cookie,
> + void (*irq_set_state)(void *cookie, bool state),
> + unsigned int (*set_vga_decode)(void *cookie, bool decode))
> +{
> + int ret = -1;
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (!vgadev)
> + goto bail;
> +
> + vgadev->irq_set_state = irq_set_state;
> + vgadev->set_vga_decode = set_vga_decode;
> + vgadev->cookie = cookie;
> + ret = 0;
> +
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return ret;
> +
> +}
> +EXPORT_SYMBOL(vga_client_register);
> +
> +/*
> + * Char driver implementation
> + *
> + * Semantics is:
> + *
> + * open : open user instance of the arbitrer. by default, it's
> + * attached to the default VGA device of the system.
> + *
> + * close : close user instance, release locks
> + *
> + * read : return a string indicating the status of the target.
> + * an IO state string is of the form {io,mem,io+mem,none},
> + * mc and ic are respectively mem and io lock counts (for
> + * debugging/diagnostic only). "decodes" indicate what the
> + * card currently decodes, "owns" indicates what is currently
> + * enabled on it, and "locks" indicates what is locked by this
> + * card. If the card is unplugged, we get "invalid" then for
> + * card_ID and an -ENODEV error is returned for any command
> + * until a new card is targeted
> + *
> + * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
> + *
> + * write : write a command to the arbiter. List of commands is:
> + *
> + * target <card_ID> : switch target to card <card_ID> (see below)
> + * lock <io_state> : acquires locks on target ("none" is invalid io_state)
> + * trylock <io_state> : non-blocking acquire locks on target
> + * unlock <io_state> : release locks on target
> + * unlock all : release all locks on target held by this user
> + * decodes <io_state> : set the legacy decoding attributes for the card
> + *
> + * poll : event if something change on any card (not just the target)
> + *
> + * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
> + * to go back to the system default card (TODO: not implemented yet).
> + * Currently, only PCI is supported as a prefix, but the userland API may
> + * support other bus types in the future, even if the current kernel
> + * implementation doesn't.
> + *
> + * Note about locks:
> + *
> + * The driver keeps track of which user has what locks on which card. It
> + * supports stacking, like the kernel one. This complexifies the implementation
> + * a bit, but makes the arbiter more tolerant to userspace problems and able
> + * to properly cleanup in all cases when a process dies.
> + * Currently, a max of 16 cards simultaneously can have locks issued from
> + * userspace for a given user (file descriptor instance) of the arbiter.
> + *
> + * If the device is hot-unplugged, there is a hook inside the module to notify
> + * they being added/removed in the system and automatically added/removed in
> + * the arbiter.
> + */
> +
> +#define MAX_USER_CARDS 16
> +#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
> +
> +/*
> + * Each user has an array of these, tracking which cards have locks
> + */
> +struct vga_arb_user_card {
> + struct pci_dev *pdev;
> + unsigned int mem_cnt;
> + unsigned int io_cnt;
> +};
> +
> +struct vga_arb_private {
> + struct list_head list;
> + struct pci_dev *target;
> + struct vga_arb_user_card cards[MAX_USER_CARDS];
> + spinlock_t lock;
> +};
> +
> +static LIST_HEAD(vga_user_list);
> +static DEFINE_SPINLOCK(vga_user_lock);
> +
> +
> +/*
> + * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
> + * returns the respective values. If the string is not in this format,
> + * it returns 0.
> + */
> +static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
> + unsigned int *bus, unsigned int *devfn)
> +{
> + int n;
> + unsigned int slot, func;
> +
> +
> + n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
> + if (n != 4)
> + return 0;
> +
> + *devfn = PCI_DEVFN(slot, func);
> +
> + return 1;
> +}
> +
> +static ssize_t vga_arb_read(struct file *file, char __user * buf,
> + size_t count, loff_t *ppos)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_device *vgadev;
> + struct pci_dev *pdev;
> + unsigned long flags;
> + size_t len;
> + int rc;
> + char *lbuf;
> +
> + lbuf = kmalloc(1024, GFP_KERNEL);
> + if (lbuf == NULL)
> + return -ENOMEM;
> +
> + /* Shields against vga_arb_device_card_gone (pci_dev going
> + * away), and allows access to vga list
> + */
> + spin_lock_irqsave(&vga_lock, flags);
> +
> + /* If we are targetting the default, use it */
> + pdev = priv->target;
> + if (pdev == NULL || pdev == PCI_INVALID_CARD) {
> + spin_unlock_irqrestore(&vga_lock, flags);
> + len = sprintf(lbuf, "invalid");
> + goto done;
> + }
> +
> + /* Find card vgadev structure */
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + /* Wow, it's not in the list, that shouldn't happen,
> + * let's fix us up and return invalid card
> + */
> + if (pdev == priv->target)
> + vga_arb_device_card_gone(pdev);
> + spin_unlock_irqrestore(&vga_lock, flags);
> + len = sprintf(lbuf, "invalid");
> + goto done;
> + }
> +
> + /* Fill the buffer with infos */
> + len = snprintf(lbuf, 1024,
> + "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
> + vga_decode_count, pci_name(pdev),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns),
> + vga_iostate_to_str(vgadev->locks),
> + vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
> +
> + spin_unlock_irqrestore(&vga_lock, flags);
> +done:
> +
> + /* Copy that to user */
> + if (len > count)
> + len = count;
> + rc = copy_to_user(buf, lbuf, len);
> + kfree(lbuf);
> + if (rc)
> + return -EFAULT;
> + return len;
> +}
> +
> +/*
> + * TODO: To avoid parsing inside kernel and to improve the speed we may
> + * consider use ioctl here
> + */
> +static ssize_t vga_arb_write(struct file *file, const char __user * buf,
> + size_t count, loff_t *ppos)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_arb_user_card *uc = NULL;
> + struct pci_dev *pdev;
> +
> + unsigned int io_state;
> +
> + char *kbuf, *curr_pos;
> + size_t remaining = count;
> +
> + int ret_val;
> + int i;
> +
> +
> + kbuf = kmalloc(count + 1, GFP_KERNEL);
> + if (!kbuf)
> + return -ENOMEM;
> +
> + if (copy_from_user(kbuf, buf, count)) {
> + kfree(kbuf);
> + return -EFAULT;
> + }
> + curr_pos = kbuf;
> + kbuf[count] = '\0'; /* Just to make sure... */
> +
> + if (strncmp(curr_pos, "lock ", 5) == 0) {
> + curr_pos += 5;
> + remaining -= 5;
> +
> + pr_devel("client 0x%X called 'lock'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + vga_get_uninterruptible(pdev, io_state);
> +
> + /* Update the client's locks lists... */
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev) {
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + priv->cards[i].io_cnt++;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + priv->cards[i].mem_cnt++;
> + break;
> + }
> + }
> +
> + ret_val = count;
> + goto done;
> + } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
> + curr_pos += 7;
> + remaining -= 7;
> +
> + pr_devel("client 0x%X called 'unlock'\n", (int)priv);
> +
> + if (strncmp(curr_pos, "all", 3) == 0)
> + io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + else {
> + if (!vga_str_to_iostate
> + (curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + /* TODO: Add this?
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + */
> + }
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev)
> + uc = &priv->cards[i];
> + }
> +
> + if (!uc)
> + return -EINVAL;
> +
> + if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0)
> + return -EINVAL;
> +
> + if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0)
> + return -EINVAL;
> +
> + vga_put(pdev, io_state);
> +
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + uc->io_cnt--;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + uc->mem_cnt--;
> +
> + ret_val = count;
> + goto done;
> + } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
> + curr_pos += 8;
> + remaining -= 8;
> +
> + pr_devel("client 0x%X called 'trylock'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + /* TODO: Add this?
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + */
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + if (vga_tryget(pdev, io_state)) {
> + /* Update the client's locks lists... */
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev) {
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + priv->cards[i].io_cnt++;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + priv->cards[i].mem_cnt++;
> + break;
> + }
> + }
> + ret_val = count;
> + goto done;
> + } else {
> + ret_val = -EBUSY;
> + goto done;
> + }
> +
> + } else if (strncmp(curr_pos, "target ", 7) == 0) {
> + unsigned int domain, bus, devfn;
> + struct vga_device *vgadev;
> +
> + curr_pos += 7;
> + remaining -= 7;
> + pr_devel("client 0x%X called 'target'\n", (int)priv);
> + /* if target is default */
> + if (!strncmp(buf, "default", 7))
> + pdev = pci_dev_get(vga_default_device());
> + else {
> + if (!vga_pci_str_to_vars(curr_pos, remaining,
> + &domain, &bus, &devfn)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> +
> + pdev = pci_get_bus_and_slot(bus, devfn);
> + if (!pdev) {
> + pr_info("vgaarb: invalid PCI address!\n");
> + ret_val = -ENODEV;
> + goto done;
> + }
> + }
> +
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + pr_info("vgaarb: this pci device is not a vga device\n");
> + pci_dev_put(pdev);
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + priv->target = pdev;
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev)
> + break;
> + if (priv->cards[i].pdev == NULL) {
> + priv->cards[i].pdev = pdev;
> + priv->cards[i].io_cnt = 0;
> + priv->cards[i].mem_cnt = 0;
> + break;
> + }
> + }
> + if (i == MAX_USER_CARDS) {
> + pr_err("vgaarb: maximum user cards number reached!\n");
> + pci_dev_put(pdev);
> + /* XXX: which value to return? */
> + ret_val = -ENOMEM;
> + goto done;
> + }
> +
> + ret_val = count;
> + pci_dev_put(pdev);
> + goto done;
> +
> +
> + } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
> + curr_pos += 8;
> + remaining -= 8;
> + pr_devel("vgaarb: client 0x%X called 'decodes'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + __vga_set_legacy_decoding(pdev, io_state, true);
> + ret_val = count;
> + goto done;
> + }
> + /* If we got here, the message written is not part of the protocol! */
> + kfree(kbuf);
> + return -EPROTO;
> +
> +done:
> + kfree(kbuf);
> + return ret_val;
> +}
How about splitting those else-if case implementations into separate
functions?
> +
> +static unsigned int vga_arb_fpoll(struct file *file, poll_table * wait)
> +{
> + struct vga_arb_private *priv = file->private_data;
> +
> + pr_devel("%s\n", __func__);
> +
> + if (priv == NULL)
> + return -ENODEV;
> + poll_wait(file, &vga_wait_queue, wait);
> + return POLLIN;
> +}
> +
> +static int vga_arb_open(struct inode *inode, struct file *file)
> +{
> + struct vga_arb_private *priv;
> + unsigned long flags;
> +
> + pr_devel("%s\n", __func__);
> +
> + priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
> + if (priv == NULL)
> + return -ENOMEM;
> + memset(priv, 0, sizeof(*priv));
> + spin_lock_init(&priv->lock);
> + file->private_data = priv;
> +
> + spin_lock_irqsave(&vga_user_lock, flags);
> + list_add(&priv->list, &vga_user_list);
> + spin_unlock_irqrestore(&vga_user_lock, flags);
> +
> + /* Set the client' lists of locks */
> + priv->target = vga_default_device(); /* Maybe this is still null! */
> + priv->cards[0].pdev = priv->target;
> + priv->cards[0].io_cnt = 0;
> + priv->cards[0].mem_cnt = 0;
> +
> +
> + return 0;
> +}
> +
> +static int vga_arb_release(struct inode *inode, struct file *file)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_arb_user_card *uc;
> + unsigned long flags;
> + int i;
> +
> + pr_devel("%s\n", __func__);
> +
> + if (priv == NULL)
> + return -ENODEV;
> +
> + spin_lock_irqsave(&vga_user_lock, flags);
> + list_del(&priv->list);
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + uc = &priv->cards[i];
> + if (uc->pdev == NULL)
> + continue;
> + pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
> + uc->io_cnt, uc->mem_cnt);
> + while (uc->io_cnt--)
> + vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
> + while (uc->mem_cnt--)
> + vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
> + }
> + spin_unlock_irqrestore(&vga_user_lock, flags);
> +
> + kfree(priv);
> +
> + return 0;
> +}
> +
> +static void vga_arb_device_card_gone(struct pci_dev *pdev)
> +{
> +}
> +
> +/*
> + * callback any registered clients to let them know we have a
> + * change in VGA cards
> + */
> +static void vga_arbiter_notify_clients(void)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + uint32_t new_decodes;
> + bool new_state;
> +
> + if (!vga_arbiter_used)
> + return;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + list_for_each_entry(vgadev, &vga_list, list) {
> + if (vga_count > 1)
> + new_state = false;
> + else
> + new_state = true;
> + if (vgadev->set_vga_decode) {
> + new_decodes = vgadev->set_vga_decode(vgadev->cookie, new_state);
> + vga_update_device_decodes(vgadev, new_decodes);
> + }
> + }
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +
> +static int pci_notify(struct notifier_block *nb, unsigned long action,
> + void *data)
> +{
> + struct device *dev = data;
> + struct pci_dev *pdev = to_pci_dev(dev);
> + bool notify = false;
> +
> + pr_devel("%s\n", __func__);
> +
> + /* For now we're only intereted in devices added and removed. I didn't
> + * test this thing here, so someone needs to double check for the
> + * cases of hotplugable vga cards. */
> + if (action == BUS_NOTIFY_ADD_DEVICE)
> + notify = vga_arbiter_add_pci_device(pdev);
> + else if (action == BUS_NOTIFY_DEL_DEVICE)
> + notify = vga_arbiter_del_pci_device(pdev);
> +
> + if (notify)
> + vga_arbiter_notify_clients();
> + return 0;
> +}
> +
> +static struct notifier_block pci_notifier = {
> + .notifier_call = pci_notify,
> +};
> +
> +static const struct file_operations vga_arb_device_fops = {
> + .read = vga_arb_read,
> + .write = vga_arb_write,
> + .poll = vga_arb_fpoll,
> + .open = vga_arb_open,
> + .release = vga_arb_release,
> +};
> +
> +static struct miscdevice vga_arb_device = {
> + MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> +};
> +
> +static int __init vga_arb_device_init(void)
> +{
> + int rc;
> + struct pci_dev *pdev;
> +
> + rc = misc_register(&vga_arb_device);
> + if (rc < 0)
> + pr_err("vgaarb: error %d registering device\n", rc);
> +
> + bus_register_notifier(&pci_bus_type, &pci_notifier);
> +
> + /* We add all pci devices satisfying vga class in the arbiter by
> + * default */
> + pdev = NULL;
> + while ((pdev =
> + pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> + PCI_ANY_ID, pdev)) != NULL)
> + vga_arbiter_add_pci_device(pdev);
> +
> + pr_info("vgaarb: loaded\n");
> + return rc;
> +}
> +subsys_initcall(vga_arb_device_init);
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index dbd0f94..d837606 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2502,6 +2502,50 @@ int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type)
> return 0;
> }
>
> +/**
> + * pci_set_vga_state - set VGA decode state on device and parents if requested
> + * @dev the PCI device
> + * @decode - true = enable decoding, false = disable decoding
> + * @command_bits PCI_COMMAND_IO and/or PCI_COMMAND_MEMORY
> + * @change_bridge - traverse ancestors and change bridges
> + */
> +int pci_set_vga_state(struct pci_dev *dev, bool decode,
> + unsigned int command_bits, bool change_bridge)
> +{
> + struct pci_bus *bus;
> + struct pci_dev *bridge;
> + u16 cmd;
> +
> + WARN_ON(command_bits & ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY));
> +
> + pci_read_config_word(dev, PCI_COMMAND, &cmd);
> + if (decode == true)
> + cmd |= command_bits;
> + else
> + cmd &= ~command_bits;
> + pci_write_config_word(dev, PCI_COMMAND, cmd);
> +
> + if (change_bridge == false)
> + return 0;
> +
> + bus = dev->bus;
> + while (bus) {
> + bridge = bus->self;
> + if (bridge) {
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &cmd);
> + if (decode == true)
> + cmd |= PCI_BRIDGE_CTL_VGA;
> + else
> + cmd &= ~PCI_BRIDGE_CTL_VGA;
> + pci_write_config_word(bridge, PCI_BRIDGE_CONTROL,
> + cmd);
> + }
> + bus = bus->parent;
> + }
> + return 0;
> +}
> +
> #define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
> static char resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
> spinlock_t resource_alignment_lock = SPIN_LOCK_UNLOCKED;
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 3b54b39..a0d9ee1 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -7,6 +7,8 @@ menu "Graphics support"
>
> source "drivers/char/agp/Kconfig"
>
> +source "drivers/gpu/vga/Kconfig"
> +
> source "drivers/gpu/drm/Kconfig"
>
> config VGASTATE
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 115fb7b..7ba6eba 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -805,6 +805,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
> int pci_cfg_space_size(struct pci_dev *dev);
> unsigned char pci_bus_max_busnr(struct pci_bus *bus);
>
> +int pci_set_vga_state(struct pci_dev *pdev, bool decode,
> + unsigned int command_bits, bool change_bridge);
> /* kmem_cache style wrapper around pci_alloc_consistent() */
>
> #include <linux/dmapool.h>
> diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
> new file mode 100644
> index 0000000..68229ce
> --- /dev/null
> +++ b/include/linux/vgaarb.h
> @@ -0,0 +1,195 @@
> +/*
> + * vgaarb.c
> + *
> + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
> + */
> +
> +#ifndef LINUX_VGA_H
> +
> +#include <asm/vga.h>
> +
> +/* Legacy VGA regions */
> +#define VGA_RSRC_NONE 0x00
> +#define VGA_RSRC_LEGACY_IO 0x01
> +#define VGA_RSRC_LEGACY_MEM 0x02
> +#define VGA_RSRC_LEGACY_MASK (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
> +/* Non-legacy access */
> +#define VGA_RSRC_NORMAL_IO 0x04
> +#define VGA_RSRC_NORMAL_MEM 0x08
> +
> +/* Passing that instead of a pci_dev to use the system "default"
> + * device, that is the one used by vgacon. Archs will probably
> + * have to provide their own vga_default_device();
> + */
> +#define VGA_DEFAULT_DEVICE (NULL)
> +
> +/* For use by clients */
> +
> +/**
> + * vga_set_legacy_decoding
> + *
> + * @pdev: pci device of the VGA card
> + * @decodes: bit mask of what legacy regions the card decodes
> + *
> + * Indicates to the arbiter if the card decodes legacy VGA IOs,
> + * legacy VGA Memory, both, or none. All cards default to both,
> + * the card driver (fbdev for example) should tell the arbiter
> + * if it has disabled legacy decoding, so the card can be left
> + * out of the arbitration process (and can be safe to take
> + * interrupts at any time.
> + */
> +extern void vga_set_legacy_decoding(struct pci_dev *pdev,
> + unsigned int decodes);
> +
> +/**
> + * vga_get - acquire & locks VGA resources
> + *
> + * pdev: pci device of the VGA card or NULL for the system default
> + * rsrc: bit mask of resources to acquire and lock
> + * interruptible: blocking should be interruptible by signals ?
I don't know the kerneldoc format, but looks like argument names
should be prefixed with @.
> + *
> + * This function acquires VGA resources for the given
> + * card and mark those resources locked. If the resource requested
> + * are "normal" (and not legacy) resources, the arbiter will first check
> + * wether the card is doing legacy decoding for that type of resource. If
> + * yes, the lock is "converted" into a legacy resource lock.
> + * The arbiter will first look for all VGA cards that might conflict
> + * and disable their IOs and/or Memory access, inlcuding VGA forwarding
> + * on P2P bridges if necessary, so that the requested resources can
> + * be used. Then, the card is marked as locking these resources and
> + * the IO and/or Memory accesse are enabled on the card (including
> + * VGA forwarding on parent P2P bridges if any).
> + * This function will block if some conflicting card is already locking
> + * one of the required resources (or any resource on a different bus
> + * segment, since P2P bridges don't differenciate VGA memory and IO
> + * afaik). You can indicate wether this blocking should be interruptible
> + * by a signal (for userland interface) or not.
> + * Must not be called at interrupt time or in atomic context.
> + * If the card already owns the resources, the function succeeds.
> + * Nested calls are supported (a per-resource counter is maintained)
> + */
> +
> +extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
> + int interruptible);
> +
> +/**
> + * vga_get_interruptible
> + *
> + * Shortcut to vga_get
> + */
> +
> +static inline int vga_get_interruptible(struct pci_dev *pdev,
> + unsigned int rsrc)
> +{
> + return vga_get(pdev, rsrc, 1);
> +}
> +
> +/**
> + * vga_get_interruptible
Should be vga_get_uninterruptible.
> + *
> + * Shortcut to vga_get
> + */
> +
> +static inline int vga_get_uninterruptible(struct pci_dev *pdev,
> + unsigned int rsrc)
> +{
> + return vga_get(pdev, rsrc, 0);
> +}
> +
> +/**
> + * vga_tryget - try to acquire & lock legacy VGA resources
> + *
> + * @pdev: pci devivce of VGA card or NULL for system default
> + * @rsrc: bit mask of resources to acquire and lock
> + *
> + * This function performs the same operation as vga_get(), but
> + * will return an error (-EBUSY) instead of blocking if the resources
> + * are already locked by another card. It can be called in any context
> + */
> +
> +extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
> +
> +/**
> + * vga_put - release lock on legacy VGA resources
> + *
> + * @pdev: pci device of VGA card or NULL for system default
> + * @rsrc: but mask of resource to release
> + *
> + * This function releases resources previously locked by vga_get()
> + * or vga_tryget(). The resources aren't disabled right away, so
> + * that a subsequence vga_get() on the same card will succeed
> + * immediately. Resources have a counter, so locks are only
> + * released if the counter reaches 0.
> + */
> +
> +extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
> +
> +
> +/**
> + * vga_default_device
> + *
> + * This can be defined by the platform. The default implementation
> + * is rather dumb and will probably only work properly on single
> + * vga card setups and/or x86 platforms.
> + *
> + * If your VGA default device is not PCI, you'll have to return
> + * NULL here. In this case, I assume it will not conflict with
> + * any PCI card. If this is not true, I'll have to define two archs
> + * hooks for enabling/disabling the VGA default device if that is
> + * possible. This may be a problem with real _ISA_ VGA cards, in
> + * addition to a PCI one. I don't know at this point how to deal
> + * with that card. Can theirs IOs be disabled at all ? If not, then
> + * I suppose it's a matter of having the proper arch hook telling
> + * us about it, so we basically never allow anybody to succeed a
> + * vga_get()...
> + */
> +
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +extern struct pci_dev *vga_default_device(void);
> +#endif
> +
> +/**
> + * vga_conflicts
> + *
> + * Architectures should define this if they have several
> + * independant PCI domains that can afford concurrent VGA
> + * decoding
> + */
> +
> +#ifndef __ARCH_HAS_VGA_CONFLICT
> +static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
> +{
> + return 1;
> +}
> +#endif
> +
> +/*
> + * Register a client with the VGA arbitration logic
> + * return value: number of VGA devices in system.
The return value is documented incorrectly here.
> + *
> + * Clients have two callback mechanisms they can use.
> + * irq enable/disable callback -
> + * If a client can't disable its GPUs VGA resources, then we
> + * need to be able to ask it to turn off its irqs when we
> + * turn off its mem and io decoding.
> + * set_vga_decode
> + * If a client can disable its GPU VGA resource, it will
> + * get a callback from this to set the encode/decode state
> + *
> + * Clients with disable abilities should check the return value
> + * of this function and if the VGA device count is > 1, should
> + * disable VGA decoding resources.
> + *
> + * Rationale: we cannot disable VGA decode resources unconditionally
> + * some single GPU laptops seem to require ACPI or BIOS access to the
> + * VGA registers to control things like backlights etc.
> + * Hopefully newer multi-GPU laptops do something saner, and desktops
> + * won't have any special ACPI for this.
> + */
> +int vga_client_register(struct pci_dev *pdev, void *cookie,
> + void (*irq_set_state)(void *cookie, bool state),
> + unsigned int (*set_vga_decode)(void *cookie, bool state));
> +
> +#endif /* LINUX_VGA_H */
> --
> 1.6.0.6
--
Pekka Paalanen
http://www.iki.fi/pq/
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 5:52 [PATCH] vga: implements VGA arbitration on Linux Dave Airlie
2009-08-11 5:52 ` [PATCH] drm: add support for VGA arbitration Dave Airlie
2009-08-11 8:14 ` [PATCH] vga: implements VGA arbitration on Linux Pekka Paalanen
@ 2009-08-11 23:17 ` Jesse Barnes
2009-08-11 23:21 ` Jesse Barnes
2009-08-12 6:48 ` Benjamin Herrenschmidt
2009-08-12 6:53 ` Benjamin Herrenschmidt
2009-08-16 15:17 ` Tiago Vignatti
4 siblings, 2 replies; 17+ messages in thread
From: Jesse Barnes @ 2009-08-11 23:17 UTC (permalink / raw)
To: Dave Airlie
Cc: Benjamin Herrenschmidt, linux-kernel, dri-devel, Tiago Vignatti
On Tue, 11 Aug 2009 15:52:06 +1000
Dave Airlie <airlied@gmail.com> wrote:
> From: Tiago Vignatti <tiago.vignatti@nokia.com>
>
> Background:
> Graphic devices are accessed through ranges in I/O or memory space.
> While most modern devices allow relocation of such ranges, some
> "Legacy" VGA devices implemented on PCI will typically have the same
> "hard-decoded" addresses as they did on ISA. For more details see
> "PCI Bus Binding to IEEE Std 1275-1994 Standard for Boot
> (Initialization Configuration) Firmware Revision 2.1" Section 7,
> Legacy Devices.
>
> The Resource Access Control (RAC) module inside the X server
> currently does the task of arbitration when more than one legacy
> device co-exists on the same machine. But the problem happens when
> these devices are trying to be accessed by different userspace
> clients (e.g. two server in parallel). Their address assignments
> conflict. Therefore an arbitration scheme _outside_ of the X server
> is needed to control the sharing of these resources. This document
> introduces the operation of the VGA arbiter implemented for Linux
> kernel.
>
> Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> Signed-off-by: Dave Airlie <airlied@redhat.com>
Ok, applied this to my linux-next branch, but I'd like to get Ben's
s-o-b before pushing it to Linus.
Ben?
Thanks,
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 23:17 ` Jesse Barnes
@ 2009-08-11 23:21 ` Jesse Barnes
2009-08-12 7:35 ` Vignatti Tiago (Nokia-D/Helsinki)
2009-08-12 6:48 ` Benjamin Herrenschmidt
1 sibling, 1 reply; 17+ messages in thread
From: Jesse Barnes @ 2009-08-11 23:21 UTC (permalink / raw)
Cc: Dave Airlie, Benjamin Herrenschmidt, linux-kernel, dri-devel,
Tiago Vignatti
On Tue, 11 Aug 2009 16:17:46 -0700
Jesse Barnes <jesse.barnes@intel.com> wrote:
> On Tue, 11 Aug 2009 15:52:06 +1000
> Dave Airlie <airlied@gmail.com> wrote:
>
> > From: Tiago Vignatti <tiago.vignatti@nokia.com>
> >
> > Background:
> > Graphic devices are accessed through ranges in I/O or memory space.
> > While most modern devices allow relocation of such ranges, some
> > "Legacy" VGA devices implemented on PCI will typically have the same
> > "hard-decoded" addresses as they did on ISA. For more details see
> > "PCI Bus Binding to IEEE Std 1275-1994 Standard for Boot
> > (Initialization Configuration) Firmware Revision 2.1" Section 7,
> > Legacy Devices.
> >
> > The Resource Access Control (RAC) module inside the X server
> > currently does the task of arbitration when more than one legacy
> > device co-exists on the same machine. But the problem happens when
> > these devices are trying to be accessed by different userspace
> > clients (e.g. two server in parallel). Their address assignments
> > conflict. Therefore an arbitration scheme _outside_ of the X server
> > is needed to control the sharing of these resources. This document
> > introduces the operation of the VGA arbiter implemented for Linux
> > kernel.
> >
> > Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> > Signed-off-by: Dave Airlie <airlied@redhat.com>
>
> Ok, applied this to my linux-next branch, but I'd like to get Ben's
> s-o-b before pushing it to Linus.
Oh yeah, and we should get the documentation merged too. I can handle
that or you can send it to Randy. Tiago?
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 23:21 ` Jesse Barnes
@ 2009-08-12 7:35 ` Vignatti Tiago (Nokia-D/Helsinki)
2009-08-12 16:02 ` Jesse Barnes
0 siblings, 1 reply; 17+ messages in thread
From: Vignatti Tiago (Nokia-D/Helsinki) @ 2009-08-12 7:35 UTC (permalink / raw)
To: Jesse Barnes
Cc: Dave Airlie, Benjamin Herrenschmidt, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
On Wed, Aug 12, 2009 at 01:21:03AM +0200, Jesse Barnes wrote:
> Oh yeah, and we should get the documentation merged too. I can handle
> that or you can send it to Randy. Tiago?
Okay, I can handle this documentation pretty easy.
But honestly I'm not sure we (or some future developer) will use it. The
header (include/linux/vgaarb.h) is already very nice documented. So, tell me
what do you think Jesse.
Cheers,
Tiago
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-12 7:35 ` Vignatti Tiago (Nokia-D/Helsinki)
@ 2009-08-12 16:02 ` Jesse Barnes
2009-08-16 15:09 ` Tiago Vignatti
0 siblings, 1 reply; 17+ messages in thread
From: Jesse Barnes @ 2009-08-12 16:02 UTC (permalink / raw)
To: tiago.vignatti
Cc: Dave Airlie, Benjamin Herrenschmidt, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
On Wed, 12 Aug 2009 10:35:16 +0300
"Vignatti Tiago (Nokia-D/Helsinki)" <tiago.vignatti@nokia.com> wrote:
> On Wed, Aug 12, 2009 at 01:21:03AM +0200, Jesse Barnes wrote:
> > Oh yeah, and we should get the documentation merged too. I can
> > handle that or you can send it to Randy. Tiago?
>
> Okay, I can handle this documentation pretty easy.
>
> But honestly I'm not sure we (or some future developer) will use it.
> The header (include/linux/vgaarb.h) is already very nice documented.
> So, tell me what do you think Jesse.
As long as it's still accurate we may as well include it.
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-12 16:02 ` Jesse Barnes
@ 2009-08-16 15:09 ` Tiago Vignatti
2009-08-25 1:08 ` Jesse Barnes
0 siblings, 1 reply; 17+ messages in thread
From: Tiago Vignatti @ 2009-08-16 15:09 UTC (permalink / raw)
To: Jesse Barnes
Cc: Dave Airlie, Benjamin Herrenschmidt, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
[-- Attachment #1: Type: text/plain, Size: 561 bytes --]
On Wed, Aug 12, 2009 at 06:02:14PM +0200, Jesse Barnes wrote:
> On Wed, 12 Aug 2009 10:35:16 +0300
> "Vignatti Tiago (Nokia-D/Helsinki)" <tiago.vignatti@nokia.com> wrote:
> > Okay, I can handle this documentation pretty easy.
> >
> > But honestly I'm not sure we (or some future developer) will use it.
> > The header (include/linux/vgaarb.h) is already very nice documented.
> > So, tell me what do you think Jesse.
>
> As long as it's still accurate we may as well include it.
Here it comes attached. Please review, Jesse.
Thank you,
Tiago
[-- Attachment #2: 0001-vga-drops-VGA-arbitration-documentation.patch --]
[-- Type: text/x-diff, Size: 9155 bytes --]
>From f65764e41e37c9a4848bb39505e40ea55e01ddfb Mon Sep 17 00:00:00 2001
From: Tiago Vignatti <tiago.vignatti@nokia.com>
Date: Sun, 16 Aug 2009 17:59:01 +0300
Subject: [PATCH] vga: drops VGA arbitration documentation
Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
---
Documentation/vgaarbiter.txt | 194 ++++++++++++++++++++++++++++++++++++++++++
1 files changed, 194 insertions(+), 0 deletions(-)
create mode 100644 Documentation/vgaarbiter.txt
diff --git a/Documentation/vgaarbiter.txt b/Documentation/vgaarbiter.txt
new file mode 100644
index 0000000..675119b
--- /dev/null
+++ b/Documentation/vgaarbiter.txt
@@ -0,0 +1,194 @@
+
+VGA Arbiter
+===========
+
+Graphic devices are accessed through ranges in I/O or memory space. While most
+modern devices allow relocation of such ranges, some "Legacy" VGA devices
+implemented on PCI will typically have the same "hard-decoded" addresses as
+they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994
+Standard for Boot (Initialization Configuration) Firmware Revision 2.1"
+Section 7, Legacy Devices.
+
+The Resource Access Control (RAC) module inside the X server [0] existed for
+the legacy VGA arbitration task (besides other bus management tasks) when more
+than one legacy device co-exists on the same machine. But the problem happens
+when these devices are trying to be accessed by different userspace clients
+(e.g. two server in parallel). Their address assignments conflict. Moreover,
+ideally, being an userspace application, it is not the role of the the X
+server to control bus resources. Therefore an arbitration scheme outside of
+the X server is needed to control the sharing of these resources. This
+document introduces the operation of the VGA arbiter implemented for Linux
+kernel.
+
+----------------------------------------------------------------------------
+
+I. Details and Theory of Operation
+ I.1 vgaarb
+ I.2 libpciaccess
+ I.3 xf86VGAArbiter (X server implementation)
+II. Credits
+III.References
+
+
+I. Details and Theory of Operation
+==================================
+
+I.1 vgaarb
+----------
+
+The vgaarb is a module of the Linux Kernel. When it is initially loaded, it
+scans all PCI devices and adds the VGA ones inside the arbitration. The
+arbiter then enables/disables the decoding on different devices of the VGA
+legacy instructions. Device which do not want/need to use the arbiter may
+explicitly tell it by calling vga_set_legacy_decoding().
+
+The kernel exports a char device interface (/dev/vga_arbiter) to the clients,
+which has the following semantics:
+
+ open : open user instance of the arbiter. By default, it's attached to
+ the default VGA device of the system.
+
+ close : close user instance. Release locks made by the user
+
+ read : return a string indicating the status of the target like:
+
+ "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
+
+ An IO state string is of the form {io,mem,io+mem,none}, mc and
+ ic are respectively mem and io lock counts (for debugging/
+ diagnostic only). "decodes" indicate what the card currently
+ decodes, "owns" indicates what is currently enabled on it, and
+ "locks" indicates what is locked by this card. If the card is
+ unplugged, we get "invalid" then for card_ID and an -ENODEV
+ error is returned for any command until a new card is targeted.
+
+
+ write : write a command to the arbiter. List of commands:
+
+ target <card_ID> : switch target to card <card_ID> (see below)
+ lock <io_state> : acquires locks on target ("none" is an invalid io_state)
+ trylock <io_state> : non-blocking acquire locks on target (returns EBUSY if
+ unsuccessful)
+ unlock <io_state> : release locks on target
+ unlock all : release all locks on target held by this user (not
+ implemented yet)
+ decodes <io_state> : set the legacy decoding attributes for the card
+
+ poll : event if something changes on any card (not just the
+ target)
+
+ card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
+ to go back to the system default card (TODO: not implemented yet). Currently,
+ only PCI is supported as a prefix, but the userland API may support other bus
+ types in the future, even if the current kernel implementation doesn't.
+
+Note about locks:
+
+The driver keeps track of which user has which locks on which card. It
+supports stacking, like the kernel one. This complexifies the implementation
+a bit, but makes the arbiter more tolerant to user space problems and able
+to properly cleanup in all cases when a process dies.
+Currently, a max of 16 cards can have locks simultaneously issued from
+user space for a given user (file descriptor instance) of the arbiter.
+
+In the case of devices hot-{un,}plugged, there is a hook - pci_notify() - to
+notify them being added/removed in the system and automatically added/removed
+in the arbiter.
+
+There's also a in-kernel API of the arbiter in the case of DRM, vgacon and
+others which may use the arbiter.
+
+
+I.2 libpciaccess
+----------------
+
+To use the vga arbiter char device it was implemented an API inside the
+libpciaccess library. One fieldd was added to struct pci_device (each device
+on the system):
+
+ /* the type of resource decoded by the device */
+ int vgaarb_rsrc;
+
+Besides it, in pci_system were added:
+
+ int vgaarb_fd;
+ int vga_count;
+ struct pci_device *vga_target;
+ struct pci_device *vga_default_dev;
+
+
+The vga_count is usually need to keep informed how many cards are being
+arbitrated, so for instance if there's only one then it can totally escape the
+scheme.
+
+
+These functions below acquire VGA resources for the given card and mark those
+resources as locked. If the resources requested are "normal" (and not legacy)
+resources, the arbiter will first check whether the card is doing legacy
+decoding for that type of resource. If yes, the lock is "converted" into a
+legacy resource lock. The arbiter will first look for all VGA cards that
+might conflict and disable their IOs and/or Memory access, including VGA
+forwarding on P2P bridges if necessary, so that the requested resources can
+be used. Then, the card is marked as locking these resources and the IO and/or
+Memory access is enabled on the card (including VGA forwarding on parent
+P2P bridges if any). In the case of vga_arb_lock(), the function will block
+if some conflicting card is already locking one of the required resources (or
+any resource on a different bus segment, since P2P bridges don't differentiate
+VGA memory and IO afaik). If the card already owns the resources, the function
+succeeds. vga_arb_trylock() will return (-EBUSY) instead of blocking. Nested
+calls are supported (a per-resource counter is maintained).
+
+
+Set the target device of this client.
+ int pci_device_vgaarb_set_target (struct pci_device *dev);
+
+
+For instance, in x86 if two devices on the same bus want to lock different
+resources, both will succeed (lock). If devices are in different buses and
+trying to lock different resources, only the first who tried succeeds.
+ int pci_device_vgaarb_lock (void);
+ int pci_device_vgaarb_trylock (void);
+
+Unlock resources of device.
+ int pci_device_vgaarb_unlock (void);
+
+Indicates to the arbiter if the card decodes legacy VGA IOs, legacy VGA
+Memory, both, or none. All cards default to both, the card driver (fbdev for
+example) should tell the arbiter if it has disabled legacy decoding, so the
+card can be left out of the arbitration process (and can be safe to take
+interrupts at any time.
+ int pci_device_vgaarb_decodes (int new_vgaarb_rsrc);
+
+Connects to the arbiter device, allocates the struct
+ int pci_device_vgaarb_init (void);
+
+Close the connection
+ void pci_device_vgaarb_fini (void);
+
+
+I.3 xf86VGAArbiter (X server implementation)
+--------------------------------------------
+
+(TODO)
+
+X server basically wraps all the functions that touch VGA registers somehow.
+
+
+II. Credits
+===========
+
+Benjamin Herrenschmidt (IBM?) started this work when he discussed such design
+with the Xorg community in 2005 [1, 2]. In the end of 2007, Paulo Zanoni and
+Tiago Vignatti (both of C3SL/Federal University of Paraná) proceeded his work
+enhancing the kernel code to adapt as a kernel module and also did the
+implementation of the user space side [3]. Now (2009) Tiago Vignatti and Dave
+Airlie finally put this work in shape and queued to Jesse Barnes' PCI tree.
+
+
+III. References
+==============
+
+[0] http://cgit.freedesktop.org/xorg/xserver/commit/?id=4b42448a2388d40f257774fbffdccaea87bd0347
+[1] http://lists.freedesktop.org/archives/xorg/2005-March/006663.html
+[2] http://lists.freedesktop.org/archives/xorg/2005-March/006745.html
+[3] http://lists.freedesktop.org/archives/xorg/2007-October/029507.html
--
1.5.6.3
^ permalink raw reply related [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-16 15:09 ` Tiago Vignatti
@ 2009-08-25 1:08 ` Jesse Barnes
0 siblings, 0 replies; 17+ messages in thread
From: Jesse Barnes @ 2009-08-25 1:08 UTC (permalink / raw)
To: tiago.vignatti
Cc: Benjamin Herrenschmidt, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
On Sun, 16 Aug 2009 18:09:36 +0300
Tiago Vignatti <tiago.vignatti@nokia.com> wrote:
> On Wed, Aug 12, 2009 at 06:02:14PM +0200, Jesse Barnes wrote:
> > On Wed, 12 Aug 2009 10:35:16 +0300
> > "Vignatti Tiago (Nokia-D/Helsinki)" <tiago.vignatti@nokia.com>
> > wrote:
> > > Okay, I can handle this documentation pretty easy.
> > >
> > > But honestly I'm not sure we (or some future developer) will use
> > > it. The header (include/linux/vgaarb.h) is already very nice
> > > documented. So, tell me what do you think Jesse.
> >
> > As long as it's still accurate we may as well include it.
>
> Here it comes attached. Please review, Jesse.
Applied to my linux-next branch, thanks. If you want the other updates
you mentioned to land, you should send a patch for them as well.
Thanks,
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 23:17 ` Jesse Barnes
2009-08-11 23:21 ` Jesse Barnes
@ 2009-08-12 6:48 ` Benjamin Herrenschmidt
2009-08-12 7:24 ` Vignatti Tiago (Nokia-D/Helsinki)
1 sibling, 1 reply; 17+ messages in thread
From: Benjamin Herrenschmidt @ 2009-08-12 6:48 UTC (permalink / raw)
To: Jesse Barnes; +Cc: Dave Airlie, linux-kernel, dri-devel, Tiago Vignatti
On Tue, 2009-08-11 at 16:17 -0700, Jesse Barnes wrote:
> Ok, applied this to my linux-next branch, but I'd like to get Ben's
> s-o-b before pushing it to Linus.
Well, S-O-B is if the code went through my hands... though in this case
I wrote the original version so I suppose it did :-) An ack for sure.
Let me have a look, I'll come back to you asap.
Cheers,
Ben.
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-12 6:48 ` Benjamin Herrenschmidt
@ 2009-08-12 7:24 ` Vignatti Tiago (Nokia-D/Helsinki)
2009-08-12 15:54 ` Jesse Barnes
0 siblings, 1 reply; 17+ messages in thread
From: Vignatti Tiago (Nokia-D/Helsinki) @ 2009-08-12 7:24 UTC (permalink / raw)
To: Benjamin Herrenschmidt
Cc: Jesse Barnes, Dave Airlie, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
On Wed, Aug 12, 2009 at 08:48:08AM +0200, Benjamin Herrenschmidt wrote:
> On Tue, 2009-08-11 at 16:17 -0700, Jesse Barnes wrote:
>
> > Ok, applied this to my linux-next branch, but I'd like to get Ben's
> > s-o-b before pushing it to Linus.
>
> Well, S-O-B is if the code went through my hands... though in this case
> I wrote the original version so I suppose it did :-) An ack for sure.
>
> Let me have a look, I'll come back to you asap.
Ohh, I feel more comfortable if the patches come with Ben's authorship. Please
do it Dave because it makes more sense (and S-O-B by me).
Cheers,
Tiago
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-12 7:24 ` Vignatti Tiago (Nokia-D/Helsinki)
@ 2009-08-12 15:54 ` Jesse Barnes
0 siblings, 0 replies; 17+ messages in thread
From: Jesse Barnes @ 2009-08-12 15:54 UTC (permalink / raw)
To: tiago.vignatti@nokia.com
Cc: Benjamin Herrenschmidt, Dave Airlie, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
On Wed, 12 Aug 2009 00:24:37 -0700
"Vignatti Tiago (Nokia-D/Helsinki)" <tiago.vignatti@nokia.com> wrote:
> On Wed, Aug 12, 2009 at 08:48:08AM +0200, Benjamin Herrenschmidt
> wrote:
> > On Tue, 2009-08-11 at 16:17 -0700, Jesse Barnes wrote:
> >
> > > Ok, applied this to my linux-next branch, but I'd like to get
> > > Ben's s-o-b before pushing it to Linus.
> >
> > Well, S-O-B is if the code went through my hands... though in this
> > case I wrote the original version so I suppose it did :-) An ack
> > for sure.
> >
> > Let me have a look, I'll come back to you asap.
>
> Ohh, I feel more comfortable if the patches come with Ben's
> authorship. Please do it Dave because it makes more sense (and S-O-B
> by me).
Ok I amended the patch to make Ben the author, with s-o-bs from Dave
and you since you both worked on the code.
Dave, do you want me to apply the DRM patch too, just to avoid having a
dependency? You could also pull my tree into yours; let me know if you
do and I won't do anymore rebases before sending Linus a pull request.
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 5:52 [PATCH] vga: implements VGA arbitration on Linux Dave Airlie
` (2 preceding siblings ...)
2009-08-11 23:17 ` Jesse Barnes
@ 2009-08-12 6:53 ` Benjamin Herrenschmidt
2009-08-16 15:17 ` Tiago Vignatti
4 siblings, 0 replies; 17+ messages in thread
From: Benjamin Herrenschmidt @ 2009-08-12 6:53 UTC (permalink / raw)
To: Dave Airlie; +Cc: jbarnes, Dave Airlie, linux-kernel, dri-devel
On Tue, 2009-08-11 at 15:52 +1000, Dave Airlie wrote:
> From: Tiago Vignatti <tiago.vignatti@nokia.com>
>
> Background:
> Graphic devices are accessed through ranges in I/O or memory space. While most
> modern devices allow relocation of such ranges, some "Legacy" VGA devices
> implemented on PCI will typically have the same "hard-decoded" addresses as
> they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994
> Standard for Boot (Initialization Configuration) Firmware Revision 2.1"
> Section 7, Legacy Devices.
>
> The Resource Access Control (RAC) module inside the X server currently does
> the task of arbitration when more than one legacy device co-exists on the same
> machine. But the problem happens when these devices are trying to be accessed
> by different userspace clients (e.g. two server in parallel). Their address
> assignments conflict. Therefore an arbitration scheme _outside_ of the X
> server is needed to control the sharing of these resources. This document
> introduces the operation of the VGA arbiter implemented for Linux kernel.
>
> Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> Signed-off-by: Dave Airlie <airlied@redhat.com>
Well, since I wrote a god deal of it:
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
Note that I do believe we still have some kind of race vs. the default
VGA device going away but it's rather minor, something to fix at some
stase though.
> ---
> drivers/gpu/Makefile | 2 +-
> drivers/gpu/vga/Kconfig | 10 +
> drivers/gpu/vga/Makefile | 1 +
> drivers/gpu/vga/vgaarb.c | 1206 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/pci/pci.c | 44 ++
> drivers/video/Kconfig | 2 +
> include/linux/pci.h | 2 +
> include/linux/vgaarb.h | 195 ++++++++
> 8 files changed, 1461 insertions(+), 1 deletions(-)
> create mode 100644 drivers/gpu/vga/Kconfig
> create mode 100644 drivers/gpu/vga/Makefile
> create mode 100644 drivers/gpu/vga/vgaarb.c
> create mode 100644 include/linux/vgaarb.h
>
> diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
> index de566cf..30879df 100644
> --- a/drivers/gpu/Makefile
> +++ b/drivers/gpu/Makefile
> @@ -1 +1 @@
> -obj-y += drm/
> +obj-y += drm/ vga/
> diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
> new file mode 100644
> index 0000000..790e675
> --- /dev/null
> +++ b/drivers/gpu/vga/Kconfig
> @@ -0,0 +1,10 @@
> +config VGA_ARB
> + bool "VGA Arbitration" if EMBEDDED
> + default y
> + depends on PCI
> + help
> + Some "legacy" VGA devices implemented on PCI typically have the same
> + hard-decoded addresses as they did on ISA. When multiple PCI devices
> + are accessed at same time they need some kind of coordination. Please
> + see Documentation/vgaarbiter.txt for more details. Select this to
> + enable VGA arbiter.
> diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
> new file mode 100644
> index 0000000..7cc8c1e
> --- /dev/null
> +++ b/drivers/gpu/vga/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_VGA_ARB) += vgaarb.o
> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> new file mode 100644
> index 0000000..199138f
> --- /dev/null
> +++ b/drivers/gpu/vga/vgaarb.c
> @@ -0,0 +1,1206 @@
> +/*
> + * vgaarb.c
> + *
> + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
> + *
> + * Implements the VGA arbitration. For details refer to
> + * Documentation/vgaarbiter.txt
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +#include <linux/errno.h>
> +#include <linux/init.h>
> +#include <linux/list.h>
> +#include <linux/sched.h>
> +#include <linux/wait.h>
> +#include <linux/spinlock.h>
> +#include <linux/poll.h>
> +#include <linux/miscdevice.h>
> +
> +#include <linux/uaccess.h>
> +
> +#include <linux/vgaarb.h>
> +
> +static void vga_arbiter_notify_clients(void);
> +/*
> + * We keep a list of all vga devices in the system to speed
> + * up the various operations of the arbiter
> + */
> +struct vga_device {
> + struct list_head list;
> + struct pci_dev *pdev;
> + unsigned int decodes; /* what does it decodes */
> + unsigned int owns; /* what does it owns */
> + unsigned int locks; /* what does it locks */
> + unsigned int io_lock_cnt; /* legacy IO lock count */
> + unsigned int mem_lock_cnt; /* legacy MEM lock count */
> + unsigned int io_norm_cnt; /* normal IO count */
> + unsigned int mem_norm_cnt; /* normal MEM count */
> +
> + /* allow IRQ enable/disable hook */
> + void *cookie;
> + void (*irq_set_state)(void *cookie, bool enable);
> + unsigned int (*set_vga_decode)(void *cookie, bool decode);
> +};
> +
> +static LIST_HEAD(vga_list);
> +static int vga_count, vga_decode_count;
> +static bool vga_arbiter_used;
> +static DEFINE_SPINLOCK(vga_lock);
> +static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
> +
> +
> +static const char *vga_iostate_to_str(unsigned int iostate)
> +{
> + /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
> + iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + switch (iostate) {
> + case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
> + return "io+mem";
> + case VGA_RSRC_LEGACY_IO:
> + return "io";
> + case VGA_RSRC_LEGACY_MEM:
> + return "mem";
> + }
> + return "none";
> +}
> +
> +static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
> +{
> + /* we could in theory hand out locks on IO and mem
> + * separately to userspace but it can cause deadlocks */
> + if (strncmp(buf, "none", 4) == 0) {
> + *io_state = VGA_RSRC_NONE;
> + return 1;
> + }
> +
> + /* XXX We're not chekcing the str_size! */
> + if (strncmp(buf, "io+mem", 6) == 0)
> + goto both;
> + else if (strncmp(buf, "io", 2) == 0)
> + goto both;
> + else if (strncmp(buf, "mem", 3) == 0)
> + goto both;
> + return 0;
> +both:
> + *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + return 1;
> +}
> +
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +/* this is only used a cookie - it should not be dereferenced */
> +static struct pci_dev *vga_default;
> +#endif
> +
> +static void vga_arb_device_card_gone(struct pci_dev *pdev);
> +
> +/* Find somebody in our list */
> +static struct vga_device *vgadev_find(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> +
> + list_for_each_entry(vgadev, &vga_list, list)
> + if (pdev == vgadev->pdev)
> + return vgadev;
> + return NULL;
> +}
> +
> +/* Returns the default VGA device (vgacon's babe) */
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +struct pci_dev *vga_default_device(void)
> +{
> + return vga_default;
> +}
> +#endif
> +
> +static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
> +{
> + if (vgadev->irq_set_state)
> + vgadev->irq_set_state(vgadev->cookie, state);
> +}
> +
> +
> +/* If we don't ever use VGA arb we should avoid
> + turning off anything anywhere due to old X servers getting
> + confused about the boot device not being VGA */
> +static void vga_check_first_use(void)
> +{
> + /* we should inform all GPUs in the system that
> + * VGA arb has occured and to try and disable resources
> + * if they can */
> + if (!vga_arbiter_used) {
> + vga_arbiter_used = true;
> + vga_arbiter_notify_clients();
> + }
> +}
> +
> +static struct vga_device *__vga_tryget(struct vga_device *vgadev,
> + unsigned int rsrc)
> +{
> + unsigned int wants, legacy_wants, match;
> + struct vga_device *conflict;
> + unsigned int pci_bits;
> + /* Account for "normal" resources to lock. If we decode the legacy,
> + * counterpart, we need to request it as well
> + */
> + if ((rsrc & VGA_RSRC_NORMAL_IO) &&
> + (vgadev->decodes & VGA_RSRC_LEGACY_IO))
> + rsrc |= VGA_RSRC_LEGACY_IO;
> + if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
> + (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
> + rsrc |= VGA_RSRC_LEGACY_MEM;
> +
> + pr_devel("%s: %d\n", __func__, rsrc);
> + pr_devel("%s: owns: %d\n", __func__, vgadev->owns);
> +
> + /* Check what resources we need to acquire */
> + wants = rsrc & ~vgadev->owns;
> +
> + /* We already own everything, just mark locked & bye bye */
> + if (wants == 0)
> + goto lock_them;
> +
> + /* We don't need to request a legacy resource, we just enable
> + * appropriate decoding and go
> + */
> + legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
> + if (legacy_wants == 0)
> + goto enable_them;
> +
> + /* Ok, we don't, let's find out how we need to kick off */
> + list_for_each_entry(conflict, &vga_list, list) {
> + unsigned int lwants = legacy_wants;
> + unsigned int change_bridge = 0;
> +
> + /* Don't conflict with myself */
> + if (vgadev == conflict)
> + continue;
> +
> + /* Check if the architecture allows a conflict between those
> + * 2 devices or if they are on separate domains
> + */
> + if (!vga_conflicts(vgadev->pdev, conflict->pdev))
> + continue;
> +
> + /* We have a possible conflict. before we go further, we must
> + * check if we sit on the same bus as the conflicting device.
> + * if we don't, then we must tie both IO and MEM resources
> + * together since there is only a single bit controlling
> + * VGA forwarding on P2P bridges
> + */
> + if (vgadev->pdev->bus != conflict->pdev->bus) {
> + change_bridge = 1;
> + lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + }
> +
> + /* Check if the guy has a lock on the resource. If he does,
> + * return the conflicting entry
> + */
> + if (conflict->locks & lwants)
> + return conflict;
> +
> + /* Ok, now check if he owns the resource we want. We don't need
> + * to check "decodes" since it should be impossible to own
> + * own legacy resources you don't decode unless I have a bug
> + * in this code...
> + */
> + WARN_ON(conflict->owns & ~conflict->decodes);
> + match = lwants & conflict->owns;
> + if (!match)
> + continue;
> +
> + /* looks like he doesn't have a lock, we can steal
> + * them from him
> + */
> + vga_irq_set_state(conflict, false);
> +
> + pci_bits = 0;
> + if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> + pci_bits |= PCI_COMMAND_MEMORY;
> + if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> + pci_bits |= PCI_COMMAND_IO;
> +
> + pci_set_vga_state(conflict->pdev, false, pci_bits,
> + change_bridge);
> + conflict->owns &= ~lwants;
> + /* If he also owned non-legacy, that is no longer the case */
> + if (lwants & VGA_RSRC_LEGACY_MEM)
> + conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
> + if (lwants & VGA_RSRC_LEGACY_IO)
> + conflict->owns &= ~VGA_RSRC_NORMAL_IO;
> + }
> +
> +enable_them:
> + /* ok dude, we got it, everybody conflicting has been disabled, let's
> + * enable us. Make sure we don't mark a bit in "owns" that we don't
> + * also have in "decodes". We can lock resources we don't decode but
> + * not own them.
> + */
> + pci_bits = 0;
> + if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> + pci_bits |= PCI_COMMAND_MEMORY;
> + if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> + pci_bits |= PCI_COMMAND_IO;
> + pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
> +
> + vga_irq_set_state(vgadev, true);
> + vgadev->owns |= (wants & vgadev->decodes);
> +lock_them:
> + vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
> + if (rsrc & VGA_RSRC_LEGACY_IO)
> + vgadev->io_lock_cnt++;
> + if (rsrc & VGA_RSRC_LEGACY_MEM)
> + vgadev->mem_lock_cnt++;
> + if (rsrc & VGA_RSRC_NORMAL_IO)
> + vgadev->io_norm_cnt++;
> + if (rsrc & VGA_RSRC_NORMAL_MEM)
> + vgadev->mem_norm_cnt++;
> +
> + return NULL;
> +}
> +
> +static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
> +{
> + unsigned int old_locks = vgadev->locks;
> +
> + pr_devel("%s\n", __func__);
> +
> + /* Update our counters, and account for equivalent legacy resources
> + * if we decode them
> + */
> + if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
> + vgadev->io_norm_cnt--;
> + if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
> + rsrc |= VGA_RSRC_LEGACY_IO;
> + }
> + if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
> + vgadev->mem_norm_cnt--;
> + if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
> + rsrc |= VGA_RSRC_LEGACY_MEM;
> + }
> + if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
> + vgadev->io_lock_cnt--;
> + if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
> + vgadev->mem_lock_cnt--;
> +
> + /* Just clear lock bits, we do lazy operations so we don't really
> + * have to bother about anything else at this point
> + */
> + if (vgadev->io_lock_cnt == 0)
> + vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
> + if (vgadev->mem_lock_cnt == 0)
> + vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
> +
> + /* Kick the wait queue in case somebody was waiting if we actually
> + * released something
> + */
> + if (old_locks != vgadev->locks)
> + wake_up_all(&vga_wait_queue);
> +}
> +
> +int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
> +{
> + struct vga_device *vgadev, *conflict;
> + unsigned long flags;
> + wait_queue_t wait;
> + int rc = 0;
> +
> + vga_check_first_use();
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return 0;
> +
> + for (;;) {
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + spin_unlock_irqrestore(&vga_lock, flags);
> + rc = -ENODEV;
> + break;
> + }
> + conflict = __vga_tryget(vgadev, rsrc);
> + spin_unlock_irqrestore(&vga_lock, flags);
> + if (conflict == NULL)
> + break;
> +
> +
> + /* We have a conflict, we wait until somebody kicks the
> + * work queue. Currently we have one work queue that we
> + * kick each time some resources are released, but it would
> + * be fairly easy to have a per device one so that we only
> + * need to attach to the conflicting device
> + */
> + init_waitqueue_entry(&wait, current);
> + add_wait_queue(&vga_wait_queue, &wait);
> + set_current_state(interruptible ?
> + TASK_INTERRUPTIBLE :
> + TASK_UNINTERRUPTIBLE);
> + if (signal_pending(current)) {
> + rc = -EINTR;
> + break;
> + }
> + schedule();
> + remove_wait_queue(&vga_wait_queue, &wait);
> + set_current_state(TASK_RUNNING);
> + }
> + return rc;
> +}
> +EXPORT_SYMBOL(vga_get);
> +
> +int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + int rc = 0;
> +
> + vga_check_first_use();
> +
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return 0;
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + rc = -ENODEV;
> + goto bail;
> + }
> + if (__vga_tryget(vgadev, rsrc))
> + rc = -EBUSY;
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return rc;
> +}
> +EXPORT_SYMBOL(vga_tryget);
> +
> +void vga_put(struct pci_dev *pdev, unsigned int rsrc)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return;
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL)
> + goto bail;
> + __vga_put(vgadev, rsrc);
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +EXPORT_SYMBOL(vga_put);
> +
> +/*
> + * Currently, we assume that the "initial" setup of the system is
> + * not sane, that is we come up with conflicting devices and let
> + * the arbiter's client decides if devices decodes or not legacy
> + * things.
> + */
> +static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + struct pci_bus *bus;
> + struct pci_dev *bridge;
> + u16 cmd;
> +
> + /* Only deal with VGA class devices */
> + if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> + return false;
> +
> + /* Allocate structure */
> + vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
> + if (vgadev == NULL) {
> + pr_err("vgaarb: failed to allocate pci device\n");
> + /* What to do on allocation failure ? For now, let's
> + * just do nothing, I'm not sure there is anything saner
> + * to be done
> + */
> + return false;
> + }
> +
> + memset(vgadev, 0, sizeof(*vgadev));
> +
> + /* Take lock & check for duplicates */
> + spin_lock_irqsave(&vga_lock, flags);
> + if (vgadev_find(pdev) != NULL) {
> + BUG_ON(1);
> + goto fail;
> + }
> + vgadev->pdev = pdev;
> +
> + /* By default, assume we decode everything */
> + vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
> + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
> +
> + /* by default mark it as decoding */
> + vga_decode_count++;
> + /* Mark that we "own" resources based on our enables, we will
> + * clear that below if the bridge isn't forwarding
> + */
> + pci_read_config_word(pdev, PCI_COMMAND, &cmd);
> + if (cmd & PCI_COMMAND_IO)
> + vgadev->owns |= VGA_RSRC_LEGACY_IO;
> + if (cmd & PCI_COMMAND_MEMORY)
> + vgadev->owns |= VGA_RSRC_LEGACY_MEM;
> +
> + /* Check if VGA cycles can get down to us */
> + bus = pdev->bus;
> + while (bus) {
> + bridge = bus->self;
> + if (bridge) {
> + u16 l;
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &l);
> + if (!(l & PCI_BRIDGE_CTL_VGA)) {
> + vgadev->owns = 0;
> + break;
> + }
> + }
> + bus = bus->parent;
> + }
> +
> + /* Deal with VGA default device. Use first enabled one
> + * by default if arch doesn't have it's own hook
> + */
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> + if (vga_default == NULL &&
> + ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
> + vga_default = pci_dev_get(pdev);
> +#endif
> +
> + /* Add to the list */
> + list_add(&vgadev->list, &vga_list);
> + vga_count++;
> + pr_info("vgaarb: device added: PCI:%s,decodes=%s,owns=%s,locks=%s\n",
> + pci_name(pdev),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns),
> + vga_iostate_to_str(vgadev->locks));
> +
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return true;
> +fail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + kfree(vgadev);
> + return false;
> +}
> +
> +static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + bool ret = true;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + ret = false;
> + goto bail;
> + }
> +
> + if (vga_default == pdev) {
> + pci_dev_put(vga_default);
> + vga_default = NULL;
> + }
> +
> + if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
> + vga_decode_count--;
> +
> + /* Remove entry from list */
> + list_del(&vgadev->list);
> + vga_count--;
> + /* Notify userland driver that the device is gone so it discards
> + * it's copies of the pci_dev pointer
> + */
> + vga_arb_device_card_gone(pdev);
> +
> + /* Wake up all possible waiters */
> + wake_up_all(&vga_wait_queue);
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + kfree(vgadev);
> + return ret;
> +}
> +
> +/* this is called with the lock */
> +static inline void vga_update_device_decodes(struct vga_device *vgadev,
> + int new_decodes)
> +{
> + int old_decodes;
> + struct vga_device *new_vgadev, *conflict;
> +
> + old_decodes = vgadev->decodes;
> + vgadev->decodes = new_decodes;
> +
> + pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
> + pci_name(vgadev->pdev),
> + vga_iostate_to_str(old_decodes),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns));
> +
> +
> + /* if we own the decodes we should move them along to
> + another card */
> + if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
> + /* set us to own nothing */
> + vgadev->owns &= ~old_decodes;
> + list_for_each_entry(new_vgadev, &vga_list, list) {
> + if ((new_vgadev != vgadev) &&
> + (new_vgadev->decodes & VGA_RSRC_LEGACY_MASK)) {
> + pr_info("vgaarb: transferring owner from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev), pci_name(new_vgadev->pdev));
> + conflict = __vga_tryget(new_vgadev, VGA_RSRC_LEGACY_MASK);
> + if (!conflict)
> + __vga_put(new_vgadev, VGA_RSRC_LEGACY_MASK);
> + break;
> + }
> + }
> + }
> +
> + /* change decodes counter */
> + if (old_decodes != new_decodes) {
> + if (new_decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
> + vga_decode_count++;
> + else
> + vga_decode_count--;
> + }
> +}
> +
> +void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes, bool userspace)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + decodes &= VGA_RSRC_LEGACY_MASK;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL)
> + goto bail;
> +
> + /* don't let userspace futz with kernel driver decodes */
> + if (userspace && vgadev->set_vga_decode)
> + goto bail;
> +
> + /* update the device decodes + counter */
> + vga_update_device_decodes(vgadev, decodes);
> +
> + /* XXX if somebody is going from "doesn't decode" to "decodes" state
> + * here, additional care must be taken as we may have pending owner
> + * ship of non-legacy region ...
> + */
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +
> +void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
> +{
> + __vga_set_legacy_decoding(pdev, decodes, false);
> +}
> +EXPORT_SYMBOL(vga_set_legacy_decoding);
> +
> +/* return number of active VGA devices */
> +/* call with NULL to unregister */
> +int vga_client_register(struct pci_dev *pdev, void *cookie,
> + void (*irq_set_state)(void *cookie, bool state),
> + unsigned int (*set_vga_decode)(void *cookie, bool decode))
> +{
> + int ret = -1;
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (!vgadev)
> + goto bail;
> +
> + vgadev->irq_set_state = irq_set_state;
> + vgadev->set_vga_decode = set_vga_decode;
> + vgadev->cookie = cookie;
> + ret = 0;
> +
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return ret;
> +
> +}
> +EXPORT_SYMBOL(vga_client_register);
> +
> +/*
> + * Char driver implementation
> + *
> + * Semantics is:
> + *
> + * open : open user instance of the arbitrer. by default, it's
> + * attached to the default VGA device of the system.
> + *
> + * close : close user instance, release locks
> + *
> + * read : return a string indicating the status of the target.
> + * an IO state string is of the form {io,mem,io+mem,none},
> + * mc and ic are respectively mem and io lock counts (for
> + * debugging/diagnostic only). "decodes" indicate what the
> + * card currently decodes, "owns" indicates what is currently
> + * enabled on it, and "locks" indicates what is locked by this
> + * card. If the card is unplugged, we get "invalid" then for
> + * card_ID and an -ENODEV error is returned for any command
> + * until a new card is targeted
> + *
> + * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
> + *
> + * write : write a command to the arbiter. List of commands is:
> + *
> + * target <card_ID> : switch target to card <card_ID> (see below)
> + * lock <io_state> : acquires locks on target ("none" is invalid io_state)
> + * trylock <io_state> : non-blocking acquire locks on target
> + * unlock <io_state> : release locks on target
> + * unlock all : release all locks on target held by this user
> + * decodes <io_state> : set the legacy decoding attributes for the card
> + *
> + * poll : event if something change on any card (not just the target)
> + *
> + * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
> + * to go back to the system default card (TODO: not implemented yet).
> + * Currently, only PCI is supported as a prefix, but the userland API may
> + * support other bus types in the future, even if the current kernel
> + * implementation doesn't.
> + *
> + * Note about locks:
> + *
> + * The driver keeps track of which user has what locks on which card. It
> + * supports stacking, like the kernel one. This complexifies the implementation
> + * a bit, but makes the arbiter more tolerant to userspace problems and able
> + * to properly cleanup in all cases when a process dies.
> + * Currently, a max of 16 cards simultaneously can have locks issued from
> + * userspace for a given user (file descriptor instance) of the arbiter.
> + *
> + * If the device is hot-unplugged, there is a hook inside the module to notify
> + * they being added/removed in the system and automatically added/removed in
> + * the arbiter.
> + */
> +
> +#define MAX_USER_CARDS 16
> +#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
> +
> +/*
> + * Each user has an array of these, tracking which cards have locks
> + */
> +struct vga_arb_user_card {
> + struct pci_dev *pdev;
> + unsigned int mem_cnt;
> + unsigned int io_cnt;
> +};
> +
> +struct vga_arb_private {
> + struct list_head list;
> + struct pci_dev *target;
> + struct vga_arb_user_card cards[MAX_USER_CARDS];
> + spinlock_t lock;
> +};
> +
> +static LIST_HEAD(vga_user_list);
> +static DEFINE_SPINLOCK(vga_user_lock);
> +
> +
> +/*
> + * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
> + * returns the respective values. If the string is not in this format,
> + * it returns 0.
> + */
> +static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
> + unsigned int *bus, unsigned int *devfn)
> +{
> + int n;
> + unsigned int slot, func;
> +
> +
> + n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
> + if (n != 4)
> + return 0;
> +
> + *devfn = PCI_DEVFN(slot, func);
> +
> + return 1;
> +}
> +
> +static ssize_t vga_arb_read(struct file *file, char __user * buf,
> + size_t count, loff_t *ppos)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_device *vgadev;
> + struct pci_dev *pdev;
> + unsigned long flags;
> + size_t len;
> + int rc;
> + char *lbuf;
> +
> + lbuf = kmalloc(1024, GFP_KERNEL);
> + if (lbuf == NULL)
> + return -ENOMEM;
> +
> + /* Shields against vga_arb_device_card_gone (pci_dev going
> + * away), and allows access to vga list
> + */
> + spin_lock_irqsave(&vga_lock, flags);
> +
> + /* If we are targetting the default, use it */
> + pdev = priv->target;
> + if (pdev == NULL || pdev == PCI_INVALID_CARD) {
> + spin_unlock_irqrestore(&vga_lock, flags);
> + len = sprintf(lbuf, "invalid");
> + goto done;
> + }
> +
> + /* Find card vgadev structure */
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + /* Wow, it's not in the list, that shouldn't happen,
> + * let's fix us up and return invalid card
> + */
> + if (pdev == priv->target)
> + vga_arb_device_card_gone(pdev);
> + spin_unlock_irqrestore(&vga_lock, flags);
> + len = sprintf(lbuf, "invalid");
> + goto done;
> + }
> +
> + /* Fill the buffer with infos */
> + len = snprintf(lbuf, 1024,
> + "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
> + vga_decode_count, pci_name(pdev),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns),
> + vga_iostate_to_str(vgadev->locks),
> + vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
> +
> + spin_unlock_irqrestore(&vga_lock, flags);
> +done:
> +
> + /* Copy that to user */
> + if (len > count)
> + len = count;
> + rc = copy_to_user(buf, lbuf, len);
> + kfree(lbuf);
> + if (rc)
> + return -EFAULT;
> + return len;
> +}
> +
> +/*
> + * TODO: To avoid parsing inside kernel and to improve the speed we may
> + * consider use ioctl here
> + */
> +static ssize_t vga_arb_write(struct file *file, const char __user * buf,
> + size_t count, loff_t *ppos)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_arb_user_card *uc = NULL;
> + struct pci_dev *pdev;
> +
> + unsigned int io_state;
> +
> + char *kbuf, *curr_pos;
> + size_t remaining = count;
> +
> + int ret_val;
> + int i;
> +
> +
> + kbuf = kmalloc(count + 1, GFP_KERNEL);
> + if (!kbuf)
> + return -ENOMEM;
> +
> + if (copy_from_user(kbuf, buf, count)) {
> + kfree(kbuf);
> + return -EFAULT;
> + }
> + curr_pos = kbuf;
> + kbuf[count] = '\0'; /* Just to make sure... */
> +
> + if (strncmp(curr_pos, "lock ", 5) == 0) {
> + curr_pos += 5;
> + remaining -= 5;
> +
> + pr_devel("client 0x%X called 'lock'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + vga_get_uninterruptible(pdev, io_state);
> +
> + /* Update the client's locks lists... */
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev) {
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + priv->cards[i].io_cnt++;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + priv->cards[i].mem_cnt++;
> + break;
> + }
> + }
> +
> + ret_val = count;
> + goto done;
> + } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
> + curr_pos += 7;
> + remaining -= 7;
> +
> + pr_devel("client 0x%X called 'unlock'\n", (int)priv);
> +
> + if (strncmp(curr_pos, "all", 3) == 0)
> + io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + else {
> + if (!vga_str_to_iostate
> + (curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + /* TODO: Add this?
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + */
> + }
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev)
> + uc = &priv->cards[i];
> + }
> +
> + if (!uc)
> + return -EINVAL;
> +
> + if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0)
> + return -EINVAL;
> +
> + if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0)
> + return -EINVAL;
> +
> + vga_put(pdev, io_state);
> +
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + uc->io_cnt--;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + uc->mem_cnt--;
> +
> + ret_val = count;
> + goto done;
> + } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
> + curr_pos += 8;
> + remaining -= 8;
> +
> + pr_devel("client 0x%X called 'trylock'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + /* TODO: Add this?
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + */
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + if (vga_tryget(pdev, io_state)) {
> + /* Update the client's locks lists... */
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev) {
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + priv->cards[i].io_cnt++;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + priv->cards[i].mem_cnt++;
> + break;
> + }
> + }
> + ret_val = count;
> + goto done;
> + } else {
> + ret_val = -EBUSY;
> + goto done;
> + }
> +
> + } else if (strncmp(curr_pos, "target ", 7) == 0) {
> + unsigned int domain, bus, devfn;
> + struct vga_device *vgadev;
> +
> + curr_pos += 7;
> + remaining -= 7;
> + pr_devel("client 0x%X called 'target'\n", (int)priv);
> + /* if target is default */
> + if (!strncmp(buf, "default", 7))
> + pdev = pci_dev_get(vga_default_device());
> + else {
> + if (!vga_pci_str_to_vars(curr_pos, remaining,
> + &domain, &bus, &devfn)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> +
> + pdev = pci_get_bus_and_slot(bus, devfn);
> + if (!pdev) {
> + pr_info("vgaarb: invalid PCI address!\n");
> + ret_val = -ENODEV;
> + goto done;
> + }
> + }
> +
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + pr_info("vgaarb: this pci device is not a vga device\n");
> + pci_dev_put(pdev);
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + priv->target = pdev;
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev)
> + break;
> + if (priv->cards[i].pdev == NULL) {
> + priv->cards[i].pdev = pdev;
> + priv->cards[i].io_cnt = 0;
> + priv->cards[i].mem_cnt = 0;
> + break;
> + }
> + }
> + if (i == MAX_USER_CARDS) {
> + pr_err("vgaarb: maximum user cards number reached!\n");
> + pci_dev_put(pdev);
> + /* XXX: which value to return? */
> + ret_val = -ENOMEM;
> + goto done;
> + }
> +
> + ret_val = count;
> + pci_dev_put(pdev);
> + goto done;
> +
> +
> + } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
> + curr_pos += 8;
> + remaining -= 8;
> + pr_devel("vgaarb: client 0x%X called 'decodes'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + __vga_set_legacy_decoding(pdev, io_state, true);
> + ret_val = count;
> + goto done;
> + }
> + /* If we got here, the message written is not part of the protocol! */
> + kfree(kbuf);
> + return -EPROTO;
> +
> +done:
> + kfree(kbuf);
> + return ret_val;
> +}
> +
> +static unsigned int vga_arb_fpoll(struct file *file, poll_table * wait)
> +{
> + struct vga_arb_private *priv = file->private_data;
> +
> + pr_devel("%s\n", __func__);
> +
> + if (priv == NULL)
> + return -ENODEV;
> + poll_wait(file, &vga_wait_queue, wait);
> + return POLLIN;
> +}
> +
> +static int vga_arb_open(struct inode *inode, struct file *file)
> +{
> + struct vga_arb_private *priv;
> + unsigned long flags;
> +
> + pr_devel("%s\n", __func__);
> +
> + priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
> + if (priv == NULL)
> + return -ENOMEM;
> + memset(priv, 0, sizeof(*priv));
> + spin_lock_init(&priv->lock);
> + file->private_data = priv;
> +
> + spin_lock_irqsave(&vga_user_lock, flags);
> + list_add(&priv->list, &vga_user_list);
> + spin_unlock_irqrestore(&vga_user_lock, flags);
> +
> + /* Set the client' lists of locks */
> + priv->target = vga_default_device(); /* Maybe this is still null! */
> + priv->cards[0].pdev = priv->target;
> + priv->cards[0].io_cnt = 0;
> + priv->cards[0].mem_cnt = 0;
> +
> +
> + return 0;
> +}
> +
> +static int vga_arb_release(struct inode *inode, struct file *file)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_arb_user_card *uc;
> + unsigned long flags;
> + int i;
> +
> + pr_devel("%s\n", __func__);
> +
> + if (priv == NULL)
> + return -ENODEV;
> +
> + spin_lock_irqsave(&vga_user_lock, flags);
> + list_del(&priv->list);
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + uc = &priv->cards[i];
> + if (uc->pdev == NULL)
> + continue;
> + pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
> + uc->io_cnt, uc->mem_cnt);
> + while (uc->io_cnt--)
> + vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
> + while (uc->mem_cnt--)
> + vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
> + }
> + spin_unlock_irqrestore(&vga_user_lock, flags);
> +
> + kfree(priv);
> +
> + return 0;
> +}
> +
> +static void vga_arb_device_card_gone(struct pci_dev *pdev)
> +{
> +}
> +
> +/*
> + * callback any registered clients to let them know we have a
> + * change in VGA cards
> + */
> +static void vga_arbiter_notify_clients(void)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + uint32_t new_decodes;
> + bool new_state;
> +
> + if (!vga_arbiter_used)
> + return;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + list_for_each_entry(vgadev, &vga_list, list) {
> + if (vga_count > 1)
> + new_state = false;
> + else
> + new_state = true;
> + if (vgadev->set_vga_decode) {
> + new_decodes = vgadev->set_vga_decode(vgadev->cookie, new_state);
> + vga_update_device_decodes(vgadev, new_decodes);
> + }
> + }
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +
> +static int pci_notify(struct notifier_block *nb, unsigned long action,
> + void *data)
> +{
> + struct device *dev = data;
> + struct pci_dev *pdev = to_pci_dev(dev);
> + bool notify = false;
> +
> + pr_devel("%s\n", __func__);
> +
> + /* For now we're only intereted in devices added and removed. I didn't
> + * test this thing here, so someone needs to double check for the
> + * cases of hotplugable vga cards. */
> + if (action == BUS_NOTIFY_ADD_DEVICE)
> + notify = vga_arbiter_add_pci_device(pdev);
> + else if (action == BUS_NOTIFY_DEL_DEVICE)
> + notify = vga_arbiter_del_pci_device(pdev);
> +
> + if (notify)
> + vga_arbiter_notify_clients();
> + return 0;
> +}
> +
> +static struct notifier_block pci_notifier = {
> + .notifier_call = pci_notify,
> +};
> +
> +static const struct file_operations vga_arb_device_fops = {
> + .read = vga_arb_read,
> + .write = vga_arb_write,
> + .poll = vga_arb_fpoll,
> + .open = vga_arb_open,
> + .release = vga_arb_release,
> +};
> +
> +static struct miscdevice vga_arb_device = {
> + MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> +};
> +
> +static int __init vga_arb_device_init(void)
> +{
> + int rc;
> + struct pci_dev *pdev;
> +
> + rc = misc_register(&vga_arb_device);
> + if (rc < 0)
> + pr_err("vgaarb: error %d registering device\n", rc);
> +
> + bus_register_notifier(&pci_bus_type, &pci_notifier);
> +
> + /* We add all pci devices satisfying vga class in the arbiter by
> + * default */
> + pdev = NULL;
> + while ((pdev =
> + pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> + PCI_ANY_ID, pdev)) != NULL)
> + vga_arbiter_add_pci_device(pdev);
> +
> + pr_info("vgaarb: loaded\n");
> + return rc;
> +}
> +subsys_initcall(vga_arb_device_init);
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index dbd0f94..d837606 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2502,6 +2502,50 @@ int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type)
> return 0;
> }
>
> +/**
> + * pci_set_vga_state - set VGA decode state on device and parents if requested
> + * @dev the PCI device
> + * @decode - true = enable decoding, false = disable decoding
> + * @command_bits PCI_COMMAND_IO and/or PCI_COMMAND_MEMORY
> + * @change_bridge - traverse ancestors and change bridges
> + */
> +int pci_set_vga_state(struct pci_dev *dev, bool decode,
> + unsigned int command_bits, bool change_bridge)
> +{
> + struct pci_bus *bus;
> + struct pci_dev *bridge;
> + u16 cmd;
> +
> + WARN_ON(command_bits & ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY));
> +
> + pci_read_config_word(dev, PCI_COMMAND, &cmd);
> + if (decode == true)
> + cmd |= command_bits;
> + else
> + cmd &= ~command_bits;
> + pci_write_config_word(dev, PCI_COMMAND, cmd);
> +
> + if (change_bridge == false)
> + return 0;
> +
> + bus = dev->bus;
> + while (bus) {
> + bridge = bus->self;
> + if (bridge) {
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &cmd);
> + if (decode == true)
> + cmd |= PCI_BRIDGE_CTL_VGA;
> + else
> + cmd &= ~PCI_BRIDGE_CTL_VGA;
> + pci_write_config_word(bridge, PCI_BRIDGE_CONTROL,
> + cmd);
> + }
> + bus = bus->parent;
> + }
> + return 0;
> +}
> +
> #define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
> static char resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
> spinlock_t resource_alignment_lock = SPIN_LOCK_UNLOCKED;
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 3b54b39..a0d9ee1 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -7,6 +7,8 @@ menu "Graphics support"
>
> source "drivers/char/agp/Kconfig"
>
> +source "drivers/gpu/vga/Kconfig"
> +
> source "drivers/gpu/drm/Kconfig"
>
> config VGASTATE
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 115fb7b..7ba6eba 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -805,6 +805,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
> int pci_cfg_space_size(struct pci_dev *dev);
> unsigned char pci_bus_max_busnr(struct pci_bus *bus);
>
> +int pci_set_vga_state(struct pci_dev *pdev, bool decode,
> + unsigned int command_bits, bool change_bridge);
> /* kmem_cache style wrapper around pci_alloc_consistent() */
>
> #include <linux/dmapool.h>
> diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
> new file mode 100644
> index 0000000..68229ce
> --- /dev/null
> +++ b/include/linux/vgaarb.h
> @@ -0,0 +1,195 @@
> +/*
> + * vgaarb.c
> + *
> + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
> + */
> +
> +#ifndef LINUX_VGA_H
> +
> +#include <asm/vga.h>
> +
> +/* Legacy VGA regions */
> +#define VGA_RSRC_NONE 0x00
> +#define VGA_RSRC_LEGACY_IO 0x01
> +#define VGA_RSRC_LEGACY_MEM 0x02
> +#define VGA_RSRC_LEGACY_MASK (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
> +/* Non-legacy access */
> +#define VGA_RSRC_NORMAL_IO 0x04
> +#define VGA_RSRC_NORMAL_MEM 0x08
> +
> +/* Passing that instead of a pci_dev to use the system "default"
> + * device, that is the one used by vgacon. Archs will probably
> + * have to provide their own vga_default_device();
> + */
> +#define VGA_DEFAULT_DEVICE (NULL)
> +
> +/* For use by clients */
> +
> +/**
> + * vga_set_legacy_decoding
> + *
> + * @pdev: pci device of the VGA card
> + * @decodes: bit mask of what legacy regions the card decodes
> + *
> + * Indicates to the arbiter if the card decodes legacy VGA IOs,
> + * legacy VGA Memory, both, or none. All cards default to both,
> + * the card driver (fbdev for example) should tell the arbiter
> + * if it has disabled legacy decoding, so the card can be left
> + * out of the arbitration process (and can be safe to take
> + * interrupts at any time.
> + */
> +extern void vga_set_legacy_decoding(struct pci_dev *pdev,
> + unsigned int decodes);
> +
> +/**
> + * vga_get - acquire & locks VGA resources
> + *
> + * pdev: pci device of the VGA card or NULL for the system default
> + * rsrc: bit mask of resources to acquire and lock
> + * interruptible: blocking should be interruptible by signals ?
> + *
> + * This function acquires VGA resources for the given
> + * card and mark those resources locked. If the resource requested
> + * are "normal" (and not legacy) resources, the arbiter will first check
> + * wether the card is doing legacy decoding for that type of resource. If
> + * yes, the lock is "converted" into a legacy resource lock.
> + * The arbiter will first look for all VGA cards that might conflict
> + * and disable their IOs and/or Memory access, inlcuding VGA forwarding
> + * on P2P bridges if necessary, so that the requested resources can
> + * be used. Then, the card is marked as locking these resources and
> + * the IO and/or Memory accesse are enabled on the card (including
> + * VGA forwarding on parent P2P bridges if any).
> + * This function will block if some conflicting card is already locking
> + * one of the required resources (or any resource on a different bus
> + * segment, since P2P bridges don't differenciate VGA memory and IO
> + * afaik). You can indicate wether this blocking should be interruptible
> + * by a signal (for userland interface) or not.
> + * Must not be called at interrupt time or in atomic context.
> + * If the card already owns the resources, the function succeeds.
> + * Nested calls are supported (a per-resource counter is maintained)
> + */
> +
> +extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
> + int interruptible);
> +
> +/**
> + * vga_get_interruptible
> + *
> + * Shortcut to vga_get
> + */
> +
> +static inline int vga_get_interruptible(struct pci_dev *pdev,
> + unsigned int rsrc)
> +{
> + return vga_get(pdev, rsrc, 1);
> +}
> +
> +/**
> + * vga_get_interruptible
> + *
> + * Shortcut to vga_get
> + */
> +
> +static inline int vga_get_uninterruptible(struct pci_dev *pdev,
> + unsigned int rsrc)
> +{
> + return vga_get(pdev, rsrc, 0);
> +}
> +
> +/**
> + * vga_tryget - try to acquire & lock legacy VGA resources
> + *
> + * @pdev: pci devivce of VGA card or NULL for system default
> + * @rsrc: bit mask of resources to acquire and lock
> + *
> + * This function performs the same operation as vga_get(), but
> + * will return an error (-EBUSY) instead of blocking if the resources
> + * are already locked by another card. It can be called in any context
> + */
> +
> +extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
> +
> +/**
> + * vga_put - release lock on legacy VGA resources
> + *
> + * @pdev: pci device of VGA card or NULL for system default
> + * @rsrc: but mask of resource to release
> + *
> + * This function releases resources previously locked by vga_get()
> + * or vga_tryget(). The resources aren't disabled right away, so
> + * that a subsequence vga_get() on the same card will succeed
> + * immediately. Resources have a counter, so locks are only
> + * released if the counter reaches 0.
> + */
> +
> +extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
> +
> +
> +/**
> + * vga_default_device
> + *
> + * This can be defined by the platform. The default implementation
> + * is rather dumb and will probably only work properly on single
> + * vga card setups and/or x86 platforms.
> + *
> + * If your VGA default device is not PCI, you'll have to return
> + * NULL here. In this case, I assume it will not conflict with
> + * any PCI card. If this is not true, I'll have to define two archs
> + * hooks for enabling/disabling the VGA default device if that is
> + * possible. This may be a problem with real _ISA_ VGA cards, in
> + * addition to a PCI one. I don't know at this point how to deal
> + * with that card. Can theirs IOs be disabled at all ? If not, then
> + * I suppose it's a matter of having the proper arch hook telling
> + * us about it, so we basically never allow anybody to succeed a
> + * vga_get()...
> + */
> +
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +extern struct pci_dev *vga_default_device(void);
> +#endif
> +
> +/**
> + * vga_conflicts
> + *
> + * Architectures should define this if they have several
> + * independant PCI domains that can afford concurrent VGA
> + * decoding
> + */
> +
> +#ifndef __ARCH_HAS_VGA_CONFLICT
> +static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
> +{
> + return 1;
> +}
> +#endif
> +
> +/*
> + * Register a client with the VGA arbitration logic
> + * return value: number of VGA devices in system.
> + *
> + * Clients have two callback mechanisms they can use.
> + * irq enable/disable callback -
> + * If a client can't disable its GPUs VGA resources, then we
> + * need to be able to ask it to turn off its irqs when we
> + * turn off its mem and io decoding.
> + * set_vga_decode
> + * If a client can disable its GPU VGA resource, it will
> + * get a callback from this to set the encode/decode state
> + *
> + * Clients with disable abilities should check the return value
> + * of this function and if the VGA device count is > 1, should
> + * disable VGA decoding resources.
> + *
> + * Rationale: we cannot disable VGA decode resources unconditionally
> + * some single GPU laptops seem to require ACPI or BIOS access to the
> + * VGA registers to control things like backlights etc.
> + * Hopefully newer multi-GPU laptops do something saner, and desktops
> + * won't have any special ACPI for this.
> + */
> +int vga_client_register(struct pci_dev *pdev, void *cookie,
> + void (*irq_set_state)(void *cookie, bool state),
> + unsigned int (*set_vga_decode)(void *cookie, bool state));
> +
> +#endif /* LINUX_VGA_H */
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-11 5:52 [PATCH] vga: implements VGA arbitration on Linux Dave Airlie
` (3 preceding siblings ...)
2009-08-12 6:53 ` Benjamin Herrenschmidt
@ 2009-08-16 15:17 ` Tiago Vignatti
2009-08-17 17:37 ` Jesse Barnes
4 siblings, 1 reply; 17+ messages in thread
From: Tiago Vignatti @ 2009-08-16 15:17 UTC (permalink / raw)
To: Dave Airlie
Cc: jbarnes@virtuousgeek.org, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net, Dave Airlie
Hi Jesse,
Just for completeness, there are some perfectionisms clean ups that I catch
bellow.
On Tue, Aug 11, 2009 at 07:52:06AM +0200, Dave Airlie wrote:
> From: Tiago Vignatti <tiago.vignatti@nokia.com>
>
> Background:
> Graphic devices are accessed through ranges in I/O or memory space. While most
> modern devices allow relocation of such ranges, some "Legacy" VGA devices
> implemented on PCI will typically have the same "hard-decoded" addresses as
> they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994
> Standard for Boot (Initialization Configuration) Firmware Revision 2.1"
> Section 7, Legacy Devices.
>
> The Resource Access Control (RAC) module inside the X server currently does
RAC already gone away. Finally!
> the task of arbitration when more than one legacy device co-exists on the same
> machine. But the problem happens when these devices are trying to be accessed
> by different userspace clients (e.g. two server in parallel). Their address
> assignments conflict. Therefore an arbitration scheme _outside_ of the X
> server is needed to control the sharing of these resources. This document
^^^^^^^^
AFAIK a patch is not a document :)
> introduces the operation of the VGA arbiter implemented for Linux kernel.
>
> Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> Signed-off-by: Dave Airlie <airlied@redhat.com>
> ---
> drivers/gpu/Makefile | 2 +-
> drivers/gpu/vga/Kconfig | 10 +
> drivers/gpu/vga/Makefile | 1 +
> drivers/gpu/vga/vgaarb.c | 1206 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/pci/pci.c | 44 ++
> drivers/video/Kconfig | 2 +
> include/linux/pci.h | 2 +
> include/linux/vgaarb.h | 195 ++++++++
> 8 files changed, 1461 insertions(+), 1 deletions(-)
> create mode 100644 drivers/gpu/vga/Kconfig
> create mode 100644 drivers/gpu/vga/Makefile
> create mode 100644 drivers/gpu/vga/vgaarb.c
> create mode 100644 include/linux/vgaarb.h
>
> diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
> index de566cf..30879df 100644
> --- a/drivers/gpu/Makefile
> +++ b/drivers/gpu/Makefile
> @@ -1 +1 @@
> -obj-y += drm/
> +obj-y += drm/ vga/
> diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
> new file mode 100644
> index 0000000..790e675
> --- /dev/null
> +++ b/drivers/gpu/vga/Kconfig
> @@ -0,0 +1,10 @@
> +config VGA_ARB
> + bool "VGA Arbitration" if EMBEDDED
> + default y
> + depends on PCI
> + help
> + Some "legacy" VGA devices implemented on PCI typically have the same
> + hard-decoded addresses as they did on ISA. When multiple PCI devices
> + are accessed at same time they need some kind of coordination. Please
> + see Documentation/vgaarbiter.txt for more details. Select this to
> + enable VGA arbiter.
> diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
> new file mode 100644
> index 0000000..7cc8c1e
> --- /dev/null
> +++ b/drivers/gpu/vga/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_VGA_ARB) += vgaarb.o
> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> new file mode 100644
> index 0000000..199138f
> --- /dev/null
> +++ b/drivers/gpu/vga/vgaarb.c
> @@ -0,0 +1,1206 @@
> +/*
> + * vgaarb.c
> + *
> + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
> + *
> + * Implements the VGA arbitration. For details refer to
> + * Documentation/vgaarbiter.txt
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +#include <linux/errno.h>
> +#include <linux/init.h>
> +#include <linux/list.h>
> +#include <linux/sched.h>
> +#include <linux/wait.h>
> +#include <linux/spinlock.h>
> +#include <linux/poll.h>
> +#include <linux/miscdevice.h>
> +
> +#include <linux/uaccess.h>
> +
> +#include <linux/vgaarb.h>
> +
> +static void vga_arbiter_notify_clients(void);
> +/*
> + * We keep a list of all vga devices in the system to speed
> + * up the various operations of the arbiter
> + */
> +struct vga_device {
> + struct list_head list;
> + struct pci_dev *pdev;
> + unsigned int decodes; /* what does it decodes */
> + unsigned int owns; /* what does it owns */
> + unsigned int locks; /* what does it locks */
> + unsigned int io_lock_cnt; /* legacy IO lock count */
> + unsigned int mem_lock_cnt; /* legacy MEM lock count */
> + unsigned int io_norm_cnt; /* normal IO count */
> + unsigned int mem_norm_cnt; /* normal MEM count */
> +
> + /* allow IRQ enable/disable hook */
> + void *cookie;
> + void (*irq_set_state)(void *cookie, bool enable);
> + unsigned int (*set_vga_decode)(void *cookie, bool decode);
> +};
> +
> +static LIST_HEAD(vga_list);
> +static int vga_count, vga_decode_count;
> +static bool vga_arbiter_used;
> +static DEFINE_SPINLOCK(vga_lock);
> +static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
> +
> +
> +static const char *vga_iostate_to_str(unsigned int iostate)
> +{
> + /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
> + iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + switch (iostate) {
> + case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
> + return "io+mem";
> + case VGA_RSRC_LEGACY_IO:
> + return "io";
> + case VGA_RSRC_LEGACY_MEM:
> + return "mem";
> + }
> + return "none";
> +}
> +
> +static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
> +{
> + /* we could in theory hand out locks on IO and mem
> + * separately to userspace but it can cause deadlocks */
> + if (strncmp(buf, "none", 4) == 0) {
> + *io_state = VGA_RSRC_NONE;
> + return 1;
> + }
> +
> + /* XXX We're not chekcing the str_size! */
> + if (strncmp(buf, "io+mem", 6) == 0)
> + goto both;
> + else if (strncmp(buf, "io", 2) == 0)
> + goto both;
> + else if (strncmp(buf, "mem", 3) == 0)
> + goto both;
> + return 0;
> +both:
> + *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + return 1;
> +}
> +
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +/* this is only used a cookie - it should not be dereferenced */
> +static struct pci_dev *vga_default;
> +#endif
> +
> +static void vga_arb_device_card_gone(struct pci_dev *pdev);
> +
> +/* Find somebody in our list */
> +static struct vga_device *vgadev_find(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> +
> + list_for_each_entry(vgadev, &vga_list, list)
> + if (pdev == vgadev->pdev)
> + return vgadev;
> + return NULL;
> +}
> +
> +/* Returns the default VGA device (vgacon's babe) */
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +struct pci_dev *vga_default_device(void)
> +{
> + return vga_default;
> +}
> +#endif
> +
> +static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
> +{
> + if (vgadev->irq_set_state)
> + vgadev->irq_set_state(vgadev->cookie, state);
> +}
> +
> +
> +/* If we don't ever use VGA arb we should avoid
> + turning off anything anywhere due to old X servers getting
> + confused about the boot device not being VGA */
> +static void vga_check_first_use(void)
> +{
> + /* we should inform all GPUs in the system that
> + * VGA arb has occured and to try and disable resources
> + * if they can */
> + if (!vga_arbiter_used) {
> + vga_arbiter_used = true;
> + vga_arbiter_notify_clients();
> + }
> +}
> +
> +static struct vga_device *__vga_tryget(struct vga_device *vgadev,
> + unsigned int rsrc)
> +{
> + unsigned int wants, legacy_wants, match;
> + struct vga_device *conflict;
> + unsigned int pci_bits;
> + /* Account for "normal" resources to lock. If we decode the legacy,
> + * counterpart, we need to request it as well
> + */
> + if ((rsrc & VGA_RSRC_NORMAL_IO) &&
> + (vgadev->decodes & VGA_RSRC_LEGACY_IO))
> + rsrc |= VGA_RSRC_LEGACY_IO;
> + if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
> + (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
> + rsrc |= VGA_RSRC_LEGACY_MEM;
> +
> + pr_devel("%s: %d\n", __func__, rsrc);
> + pr_devel("%s: owns: %d\n", __func__, vgadev->owns);
> +
> + /* Check what resources we need to acquire */
> + wants = rsrc & ~vgadev->owns;
> +
> + /* We already own everything, just mark locked & bye bye */
> + if (wants == 0)
> + goto lock_them;
> +
> + /* We don't need to request a legacy resource, we just enable
> + * appropriate decoding and go
> + */
> + legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
> + if (legacy_wants == 0)
> + goto enable_them;
> +
> + /* Ok, we don't, let's find out how we need to kick off */
> + list_for_each_entry(conflict, &vga_list, list) {
> + unsigned int lwants = legacy_wants;
> + unsigned int change_bridge = 0;
> +
> + /* Don't conflict with myself */
> + if (vgadev == conflict)
> + continue;
> +
> + /* Check if the architecture allows a conflict between those
> + * 2 devices or if they are on separate domains
> + */
> + if (!vga_conflicts(vgadev->pdev, conflict->pdev))
> + continue;
> +
> + /* We have a possible conflict. before we go further, we must
> + * check if we sit on the same bus as the conflicting device.
> + * if we don't, then we must tie both IO and MEM resources
> + * together since there is only a single bit controlling
> + * VGA forwarding on P2P bridges
> + */
> + if (vgadev->pdev->bus != conflict->pdev->bus) {
> + change_bridge = 1;
> + lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + }
> +
> + /* Check if the guy has a lock on the resource. If he does,
> + * return the conflicting entry
> + */
> + if (conflict->locks & lwants)
> + return conflict;
> +
> + /* Ok, now check if he owns the resource we want. We don't need
> + * to check "decodes" since it should be impossible to own
> + * own legacy resources you don't decode unless I have a bug
> + * in this code...
> + */
> + WARN_ON(conflict->owns & ~conflict->decodes);
> + match = lwants & conflict->owns;
> + if (!match)
> + continue;
> +
> + /* looks like he doesn't have a lock, we can steal
> + * them from him
> + */
> + vga_irq_set_state(conflict, false);
> +
> + pci_bits = 0;
> + if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> + pci_bits |= PCI_COMMAND_MEMORY;
> + if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> + pci_bits |= PCI_COMMAND_IO;
> +
> + pci_set_vga_state(conflict->pdev, false, pci_bits,
> + change_bridge);
> + conflict->owns &= ~lwants;
> + /* If he also owned non-legacy, that is no longer the case */
> + if (lwants & VGA_RSRC_LEGACY_MEM)
> + conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
> + if (lwants & VGA_RSRC_LEGACY_IO)
> + conflict->owns &= ~VGA_RSRC_NORMAL_IO;
> + }
> +
> +enable_them:
> + /* ok dude, we got it, everybody conflicting has been disabled, let's
> + * enable us. Make sure we don't mark a bit in "owns" that we don't
> + * also have in "decodes". We can lock resources we don't decode but
> + * not own them.
> + */
> + pci_bits = 0;
> + if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> + pci_bits |= PCI_COMMAND_MEMORY;
> + if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> + pci_bits |= PCI_COMMAND_IO;
> + pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
> +
> + vga_irq_set_state(vgadev, true);
> + vgadev->owns |= (wants & vgadev->decodes);
> +lock_them:
> + vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
> + if (rsrc & VGA_RSRC_LEGACY_IO)
> + vgadev->io_lock_cnt++;
> + if (rsrc & VGA_RSRC_LEGACY_MEM)
> + vgadev->mem_lock_cnt++;
> + if (rsrc & VGA_RSRC_NORMAL_IO)
> + vgadev->io_norm_cnt++;
> + if (rsrc & VGA_RSRC_NORMAL_MEM)
> + vgadev->mem_norm_cnt++;
> +
> + return NULL;
> +}
> +
> +static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
> +{
> + unsigned int old_locks = vgadev->locks;
> +
> + pr_devel("%s\n", __func__);
> +
> + /* Update our counters, and account for equivalent legacy resources
> + * if we decode them
> + */
> + if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
> + vgadev->io_norm_cnt--;
> + if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
> + rsrc |= VGA_RSRC_LEGACY_IO;
> + }
> + if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
> + vgadev->mem_norm_cnt--;
> + if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
> + rsrc |= VGA_RSRC_LEGACY_MEM;
> + }
> + if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
> + vgadev->io_lock_cnt--;
> + if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
> + vgadev->mem_lock_cnt--;
> +
> + /* Just clear lock bits, we do lazy operations so we don't really
> + * have to bother about anything else at this point
> + */
> + if (vgadev->io_lock_cnt == 0)
> + vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
> + if (vgadev->mem_lock_cnt == 0)
> + vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
> +
> + /* Kick the wait queue in case somebody was waiting if we actually
> + * released something
> + */
> + if (old_locks != vgadev->locks)
> + wake_up_all(&vga_wait_queue);
> +}
> +
> +int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
> +{
> + struct vga_device *vgadev, *conflict;
> + unsigned long flags;
> + wait_queue_t wait;
> + int rc = 0;
> +
> + vga_check_first_use();
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return 0;
> +
> + for (;;) {
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + spin_unlock_irqrestore(&vga_lock, flags);
> + rc = -ENODEV;
> + break;
> + }
> + conflict = __vga_tryget(vgadev, rsrc);
> + spin_unlock_irqrestore(&vga_lock, flags);
> + if (conflict == NULL)
> + break;
> +
> +
> + /* We have a conflict, we wait until somebody kicks the
> + * work queue. Currently we have one work queue that we
> + * kick each time some resources are released, but it would
> + * be fairly easy to have a per device one so that we only
> + * need to attach to the conflicting device
> + */
> + init_waitqueue_entry(&wait, current);
> + add_wait_queue(&vga_wait_queue, &wait);
> + set_current_state(interruptible ?
> + TASK_INTERRUPTIBLE :
> + TASK_UNINTERRUPTIBLE);
> + if (signal_pending(current)) {
> + rc = -EINTR;
> + break;
> + }
> + schedule();
> + remove_wait_queue(&vga_wait_queue, &wait);
> + set_current_state(TASK_RUNNING);
> + }
> + return rc;
> +}
> +EXPORT_SYMBOL(vga_get);
> +
> +int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + int rc = 0;
> +
> + vga_check_first_use();
> +
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return 0;
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + rc = -ENODEV;
> + goto bail;
> + }
> + if (__vga_tryget(vgadev, rsrc))
> + rc = -EBUSY;
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return rc;
> +}
> +EXPORT_SYMBOL(vga_tryget);
> +
> +void vga_put(struct pci_dev *pdev, unsigned int rsrc)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + /* The one who calls us should check for this, but lets be sure... */
> + if (pdev == NULL)
> + pdev = vga_default_device();
> + if (pdev == NULL)
> + return;
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL)
> + goto bail;
> + __vga_put(vgadev, rsrc);
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +EXPORT_SYMBOL(vga_put);
> +
> +/*
> + * Currently, we assume that the "initial" setup of the system is
> + * not sane, that is we come up with conflicting devices and let
> + * the arbiter's client decides if devices decodes or not legacy
> + * things.
> + */
> +static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + struct pci_bus *bus;
> + struct pci_dev *bridge;
> + u16 cmd;
> +
> + /* Only deal with VGA class devices */
> + if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> + return false;
> +
> + /* Allocate structure */
> + vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
> + if (vgadev == NULL) {
> + pr_err("vgaarb: failed to allocate pci device\n");
> + /* What to do on allocation failure ? For now, let's
> + * just do nothing, I'm not sure there is anything saner
> + * to be done
> + */
> + return false;
> + }
> +
> + memset(vgadev, 0, sizeof(*vgadev));
> +
> + /* Take lock & check for duplicates */
> + spin_lock_irqsave(&vga_lock, flags);
> + if (vgadev_find(pdev) != NULL) {
> + BUG_ON(1);
> + goto fail;
> + }
> + vgadev->pdev = pdev;
> +
> + /* By default, assume we decode everything */
> + vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
> + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
> +
> + /* by default mark it as decoding */
> + vga_decode_count++;
> + /* Mark that we "own" resources based on our enables, we will
> + * clear that below if the bridge isn't forwarding
> + */
> + pci_read_config_word(pdev, PCI_COMMAND, &cmd);
> + if (cmd & PCI_COMMAND_IO)
> + vgadev->owns |= VGA_RSRC_LEGACY_IO;
> + if (cmd & PCI_COMMAND_MEMORY)
> + vgadev->owns |= VGA_RSRC_LEGACY_MEM;
> +
> + /* Check if VGA cycles can get down to us */
> + bus = pdev->bus;
> + while (bus) {
> + bridge = bus->self;
> + if (bridge) {
> + u16 l;
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &l);
> + if (!(l & PCI_BRIDGE_CTL_VGA)) {
> + vgadev->owns = 0;
> + break;
> + }
> + }
> + bus = bus->parent;
> + }
> +
> + /* Deal with VGA default device. Use first enabled one
> + * by default if arch doesn't have it's own hook
> + */
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> + if (vga_default == NULL &&
> + ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
> + vga_default = pci_dev_get(pdev);
> +#endif
> +
> + /* Add to the list */
> + list_add(&vgadev->list, &vga_list);
> + vga_count++;
> + pr_info("vgaarb: device added: PCI:%s,decodes=%s,owns=%s,locks=%s\n",
> + pci_name(pdev),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns),
> + vga_iostate_to_str(vgadev->locks));
> +
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return true;
> +fail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + kfree(vgadev);
> + return false;
> +}
> +
> +static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + bool ret = true;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + ret = false;
> + goto bail;
> + }
> +
> + if (vga_default == pdev) {
> + pci_dev_put(vga_default);
> + vga_default = NULL;
> + }
> +
> + if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
> + vga_decode_count--;
> +
> + /* Remove entry from list */
> + list_del(&vgadev->list);
> + vga_count--;
> + /* Notify userland driver that the device is gone so it discards
> + * it's copies of the pci_dev pointer
> + */
> + vga_arb_device_card_gone(pdev);
> +
> + /* Wake up all possible waiters */
> + wake_up_all(&vga_wait_queue);
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + kfree(vgadev);
> + return ret;
> +}
> +
> +/* this is called with the lock */
> +static inline void vga_update_device_decodes(struct vga_device *vgadev,
> + int new_decodes)
> +{
> + int old_decodes;
> + struct vga_device *new_vgadev, *conflict;
> +
> + old_decodes = vgadev->decodes;
> + vgadev->decodes = new_decodes;
> +
> + pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
> + pci_name(vgadev->pdev),
> + vga_iostate_to_str(old_decodes),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns));
> +
> +
> + /* if we own the decodes we should move them along to
> + another card */
> + if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
> + /* set us to own nothing */
> + vgadev->owns &= ~old_decodes;
> + list_for_each_entry(new_vgadev, &vga_list, list) {
> + if ((new_vgadev != vgadev) &&
> + (new_vgadev->decodes & VGA_RSRC_LEGACY_MASK)) {
> + pr_info("vgaarb: transferring owner from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev), pci_name(new_vgadev->pdev));
> + conflict = __vga_tryget(new_vgadev, VGA_RSRC_LEGACY_MASK);
> + if (!conflict)
> + __vga_put(new_vgadev, VGA_RSRC_LEGACY_MASK);
> + break;
> + }
> + }
> + }
> +
> + /* change decodes counter */
> + if (old_decodes != new_decodes) {
> + if (new_decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
> + vga_decode_count++;
> + else
> + vga_decode_count--;
> + }
> +}
> +
> +void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes, bool userspace)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + decodes &= VGA_RSRC_LEGACY_MASK;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL)
> + goto bail;
> +
> + /* don't let userspace futz with kernel driver decodes */
> + if (userspace && vgadev->set_vga_decode)
> + goto bail;
> +
> + /* update the device decodes + counter */
> + vga_update_device_decodes(vgadev, decodes);
> +
> + /* XXX if somebody is going from "doesn't decode" to "decodes" state
> + * here, additional care must be taken as we may have pending owner
> + * ship of non-legacy region ...
> + */
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +
> +void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
> +{
> + __vga_set_legacy_decoding(pdev, decodes, false);
> +}
> +EXPORT_SYMBOL(vga_set_legacy_decoding);
> +
> +/* return number of active VGA devices */
> +/* call with NULL to unregister */
> +int vga_client_register(struct pci_dev *pdev, void *cookie,
> + void (*irq_set_state)(void *cookie, bool state),
> + unsigned int (*set_vga_decode)(void *cookie, bool decode))
> +{
> + int ret = -1;
> + struct vga_device *vgadev;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + vgadev = vgadev_find(pdev);
> + if (!vgadev)
> + goto bail;
> +
> + vgadev->irq_set_state = irq_set_state;
> + vgadev->set_vga_decode = set_vga_decode;
> + vgadev->cookie = cookie;
> + ret = 0;
> +
> +bail:
> + spin_unlock_irqrestore(&vga_lock, flags);
> + return ret;
> +
> +}
> +EXPORT_SYMBOL(vga_client_register);
> +
> +/*
> + * Char driver implementation
> + *
> + * Semantics is:
> + *
> + * open : open user instance of the arbitrer. by default, it's
> + * attached to the default VGA device of the system.
> + *
> + * close : close user instance, release locks
> + *
> + * read : return a string indicating the status of the target.
> + * an IO state string is of the form {io,mem,io+mem,none},
> + * mc and ic are respectively mem and io lock counts (for
> + * debugging/diagnostic only). "decodes" indicate what the
> + * card currently decodes, "owns" indicates what is currently
> + * enabled on it, and "locks" indicates what is locked by this
> + * card. If the card is unplugged, we get "invalid" then for
> + * card_ID and an -ENODEV error is returned for any command
> + * until a new card is targeted
> + *
> + * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
> + *
> + * write : write a command to the arbiter. List of commands is:
> + *
> + * target <card_ID> : switch target to card <card_ID> (see below)
> + * lock <io_state> : acquires locks on target ("none" is invalid io_state)
> + * trylock <io_state> : non-blocking acquire locks on target
> + * unlock <io_state> : release locks on target
> + * unlock all : release all locks on target held by this user
> + * decodes <io_state> : set the legacy decoding attributes for the card
> + *
> + * poll : event if something change on any card (not just the target)
> + *
> + * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
> + * to go back to the system default card (TODO: not implemented yet).
> + * Currently, only PCI is supported as a prefix, but the userland API may
> + * support other bus types in the future, even if the current kernel
> + * implementation doesn't.
> + *
> + * Note about locks:
> + *
> + * The driver keeps track of which user has what locks on which card. It
> + * supports stacking, like the kernel one. This complexifies the implementation
> + * a bit, but makes the arbiter more tolerant to userspace problems and able
> + * to properly cleanup in all cases when a process dies.
> + * Currently, a max of 16 cards simultaneously can have locks issued from
> + * userspace for a given user (file descriptor instance) of the arbiter.
> + *
> + * If the device is hot-unplugged, there is a hook inside the module to notify
> + * they being added/removed in the system and automatically added/removed in
> + * the arbiter.
> + */
> +
> +#define MAX_USER_CARDS 16
> +#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
> +
> +/*
> + * Each user has an array of these, tracking which cards have locks
> + */
> +struct vga_arb_user_card {
> + struct pci_dev *pdev;
> + unsigned int mem_cnt;
> + unsigned int io_cnt;
> +};
> +
> +struct vga_arb_private {
> + struct list_head list;
> + struct pci_dev *target;
> + struct vga_arb_user_card cards[MAX_USER_CARDS];
> + spinlock_t lock;
> +};
> +
> +static LIST_HEAD(vga_user_list);
> +static DEFINE_SPINLOCK(vga_user_lock);
> +
> +
> +/*
> + * This function gets a string in the format: "PCI:domain:bus:dev.fn" and
> + * returns the respective values. If the string is not in this format,
> + * it returns 0.
> + */
> +static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
> + unsigned int *bus, unsigned int *devfn)
> +{
> + int n;
> + unsigned int slot, func;
> +
> +
> + n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
> + if (n != 4)
> + return 0;
> +
> + *devfn = PCI_DEVFN(slot, func);
> +
> + return 1;
> +}
> +
> +static ssize_t vga_arb_read(struct file *file, char __user * buf,
> + size_t count, loff_t *ppos)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_device *vgadev;
> + struct pci_dev *pdev;
> + unsigned long flags;
> + size_t len;
> + int rc;
> + char *lbuf;
> +
> + lbuf = kmalloc(1024, GFP_KERNEL);
> + if (lbuf == NULL)
> + return -ENOMEM;
> +
> + /* Shields against vga_arb_device_card_gone (pci_dev going
> + * away), and allows access to vga list
> + */
> + spin_lock_irqsave(&vga_lock, flags);
> +
> + /* If we are targetting the default, use it */
> + pdev = priv->target;
> + if (pdev == NULL || pdev == PCI_INVALID_CARD) {
> + spin_unlock_irqrestore(&vga_lock, flags);
> + len = sprintf(lbuf, "invalid");
> + goto done;
> + }
> +
> + /* Find card vgadev structure */
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + /* Wow, it's not in the list, that shouldn't happen,
> + * let's fix us up and return invalid card
> + */
> + if (pdev == priv->target)
> + vga_arb_device_card_gone(pdev);
> + spin_unlock_irqrestore(&vga_lock, flags);
> + len = sprintf(lbuf, "invalid");
> + goto done;
> + }
> +
> + /* Fill the buffer with infos */
> + len = snprintf(lbuf, 1024,
> + "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
> + vga_decode_count, pci_name(pdev),
> + vga_iostate_to_str(vgadev->decodes),
> + vga_iostate_to_str(vgadev->owns),
> + vga_iostate_to_str(vgadev->locks),
> + vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
> +
> + spin_unlock_irqrestore(&vga_lock, flags);
> +done:
> +
> + /* Copy that to user */
> + if (len > count)
> + len = count;
> + rc = copy_to_user(buf, lbuf, len);
> + kfree(lbuf);
> + if (rc)
> + return -EFAULT;
> + return len;
> +}
> +
> +/*
> + * TODO: To avoid parsing inside kernel and to improve the speed we may
> + * consider use ioctl here
> + */
> +static ssize_t vga_arb_write(struct file *file, const char __user * buf,
> + size_t count, loff_t *ppos)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_arb_user_card *uc = NULL;
> + struct pci_dev *pdev;
> +
> + unsigned int io_state;
> +
> + char *kbuf, *curr_pos;
> + size_t remaining = count;
> +
> + int ret_val;
> + int i;
> +
> +
> + kbuf = kmalloc(count + 1, GFP_KERNEL);
> + if (!kbuf)
> + return -ENOMEM;
> +
> + if (copy_from_user(kbuf, buf, count)) {
> + kfree(kbuf);
> + return -EFAULT;
> + }
> + curr_pos = kbuf;
> + kbuf[count] = '\0'; /* Just to make sure... */
> +
> + if (strncmp(curr_pos, "lock ", 5) == 0) {
> + curr_pos += 5;
> + remaining -= 5;
> +
> + pr_devel("client 0x%X called 'lock'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + vga_get_uninterruptible(pdev, io_state);
> +
> + /* Update the client's locks lists... */
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev) {
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + priv->cards[i].io_cnt++;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + priv->cards[i].mem_cnt++;
> + break;
> + }
> + }
> +
> + ret_val = count;
> + goto done;
> + } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
> + curr_pos += 7;
> + remaining -= 7;
> +
> + pr_devel("client 0x%X called 'unlock'\n", (int)priv);
> +
> + if (strncmp(curr_pos, "all", 3) == 0)
> + io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> + else {
> + if (!vga_str_to_iostate
> + (curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + /* TODO: Add this?
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + */
> + }
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev)
> + uc = &priv->cards[i];
> + }
> +
> + if (!uc)
> + return -EINVAL;
> +
> + if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0)
> + return -EINVAL;
> +
> + if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0)
> + return -EINVAL;
> +
> + vga_put(pdev, io_state);
> +
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + uc->io_cnt--;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + uc->mem_cnt--;
> +
> + ret_val = count;
> + goto done;
> + } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
> + curr_pos += 8;
> + remaining -= 8;
> +
> + pr_devel("client 0x%X called 'trylock'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + /* TODO: Add this?
> + if (io_state == VGA_RSRC_NONE) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + */
> +
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + if (vga_tryget(pdev, io_state)) {
> + /* Update the client's locks lists... */
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev) {
> + if (io_state & VGA_RSRC_LEGACY_IO)
> + priv->cards[i].io_cnt++;
> + if (io_state & VGA_RSRC_LEGACY_MEM)
> + priv->cards[i].mem_cnt++;
> + break;
> + }
> + }
> + ret_val = count;
> + goto done;
> + } else {
> + ret_val = -EBUSY;
> + goto done;
> + }
> +
> + } else if (strncmp(curr_pos, "target ", 7) == 0) {
> + unsigned int domain, bus, devfn;
> + struct vga_device *vgadev;
> +
> + curr_pos += 7;
> + remaining -= 7;
> + pr_devel("client 0x%X called 'target'\n", (int)priv);
> + /* if target is default */
> + if (!strncmp(buf, "default", 7))
> + pdev = pci_dev_get(vga_default_device());
> + else {
> + if (!vga_pci_str_to_vars(curr_pos, remaining,
> + &domain, &bus, &devfn)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> +
> + pdev = pci_get_bus_and_slot(bus, devfn);
> + if (!pdev) {
> + pr_info("vgaarb: invalid PCI address!\n");
> + ret_val = -ENODEV;
> + goto done;
> + }
> + }
> +
> + vgadev = vgadev_find(pdev);
> + if (vgadev == NULL) {
> + pr_info("vgaarb: this pci device is not a vga device\n");
> + pci_dev_put(pdev);
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + priv->target = pdev;
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + if (priv->cards[i].pdev == pdev)
> + break;
> + if (priv->cards[i].pdev == NULL) {
> + priv->cards[i].pdev = pdev;
> + priv->cards[i].io_cnt = 0;
> + priv->cards[i].mem_cnt = 0;
> + break;
> + }
> + }
> + if (i == MAX_USER_CARDS) {
> + pr_err("vgaarb: maximum user cards number reached!\n");
> + pci_dev_put(pdev);
> + /* XXX: which value to return? */
> + ret_val = -ENOMEM;
> + goto done;
> + }
> +
> + ret_val = count;
> + pci_dev_put(pdev);
> + goto done;
> +
> +
> + } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
> + curr_pos += 8;
> + remaining -= 8;
> + pr_devel("vgaarb: client 0x%X called 'decodes'\n", (int)priv);
> +
> + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
> + ret_val = -EPROTO;
> + goto done;
> + }
> + pdev = priv->target;
> + if (priv->target == NULL) {
> + ret_val = -ENODEV;
> + goto done;
> + }
> +
> + __vga_set_legacy_decoding(pdev, io_state, true);
> + ret_val = count;
> + goto done;
> + }
> + /* If we got here, the message written is not part of the protocol! */
> + kfree(kbuf);
> + return -EPROTO;
> +
> +done:
> + kfree(kbuf);
> + return ret_val;
> +}
> +
> +static unsigned int vga_arb_fpoll(struct file *file, poll_table * wait)
> +{
> + struct vga_arb_private *priv = file->private_data;
> +
> + pr_devel("%s\n", __func__);
> +
> + if (priv == NULL)
> + return -ENODEV;
> + poll_wait(file, &vga_wait_queue, wait);
> + return POLLIN;
> +}
> +
> +static int vga_arb_open(struct inode *inode, struct file *file)
> +{
> + struct vga_arb_private *priv;
> + unsigned long flags;
> +
> + pr_devel("%s\n", __func__);
> +
> + priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
> + if (priv == NULL)
> + return -ENOMEM;
> + memset(priv, 0, sizeof(*priv));
> + spin_lock_init(&priv->lock);
> + file->private_data = priv;
> +
> + spin_lock_irqsave(&vga_user_lock, flags);
> + list_add(&priv->list, &vga_user_list);
> + spin_unlock_irqrestore(&vga_user_lock, flags);
> +
> + /* Set the client' lists of locks */
> + priv->target = vga_default_device(); /* Maybe this is still null! */
> + priv->cards[0].pdev = priv->target;
> + priv->cards[0].io_cnt = 0;
> + priv->cards[0].mem_cnt = 0;
> +
> +
> + return 0;
> +}
> +
> +static int vga_arb_release(struct inode *inode, struct file *file)
> +{
> + struct vga_arb_private *priv = file->private_data;
> + struct vga_arb_user_card *uc;
> + unsigned long flags;
> + int i;
> +
> + pr_devel("%s\n", __func__);
> +
> + if (priv == NULL)
> + return -ENODEV;
> +
> + spin_lock_irqsave(&vga_user_lock, flags);
> + list_del(&priv->list);
> + for (i = 0; i < MAX_USER_CARDS; i++) {
> + uc = &priv->cards[i];
> + if (uc->pdev == NULL)
> + continue;
> + pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
> + uc->io_cnt, uc->mem_cnt);
> + while (uc->io_cnt--)
> + vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
> + while (uc->mem_cnt--)
> + vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
> + }
> + spin_unlock_irqrestore(&vga_user_lock, flags);
> +
> + kfree(priv);
> +
> + return 0;
> +}
> +
> +static void vga_arb_device_card_gone(struct pci_dev *pdev)
> +{
> +}
> +
> +/*
> + * callback any registered clients to let them know we have a
> + * change in VGA cards
> + */
> +static void vga_arbiter_notify_clients(void)
> +{
> + struct vga_device *vgadev;
> + unsigned long flags;
> + uint32_t new_decodes;
> + bool new_state;
> +
> + if (!vga_arbiter_used)
> + return;
> +
> + spin_lock_irqsave(&vga_lock, flags);
> + list_for_each_entry(vgadev, &vga_list, list) {
> + if (vga_count > 1)
> + new_state = false;
> + else
> + new_state = true;
> + if (vgadev->set_vga_decode) {
> + new_decodes = vgadev->set_vga_decode(vgadev->cookie, new_state);
> + vga_update_device_decodes(vgadev, new_decodes);
> + }
> + }
> + spin_unlock_irqrestore(&vga_lock, flags);
> +}
> +
> +static int pci_notify(struct notifier_block *nb, unsigned long action,
> + void *data)
> +{
> + struct device *dev = data;
> + struct pci_dev *pdev = to_pci_dev(dev);
> + bool notify = false;
> +
> + pr_devel("%s\n", __func__);
> +
> + /* For now we're only intereted in devices added and removed. I didn't
> + * test this thing here, so someone needs to double check for the
> + * cases of hotplugable vga cards. */
> + if (action == BUS_NOTIFY_ADD_DEVICE)
> + notify = vga_arbiter_add_pci_device(pdev);
> + else if (action == BUS_NOTIFY_DEL_DEVICE)
> + notify = vga_arbiter_del_pci_device(pdev);
> +
> + if (notify)
> + vga_arbiter_notify_clients();
> + return 0;
> +}
> +
> +static struct notifier_block pci_notifier = {
> + .notifier_call = pci_notify,
> +};
> +
> +static const struct file_operations vga_arb_device_fops = {
> + .read = vga_arb_read,
> + .write = vga_arb_write,
> + .poll = vga_arb_fpoll,
> + .open = vga_arb_open,
> + .release = vga_arb_release,
> +};
> +
> +static struct miscdevice vga_arb_device = {
> + MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> +};
> +
> +static int __init vga_arb_device_init(void)
> +{
> + int rc;
> + struct pci_dev *pdev;
> +
> + rc = misc_register(&vga_arb_device);
> + if (rc < 0)
> + pr_err("vgaarb: error %d registering device\n", rc);
> +
> + bus_register_notifier(&pci_bus_type, &pci_notifier);
> +
> + /* We add all pci devices satisfying vga class in the arbiter by
> + * default */
> + pdev = NULL;
> + while ((pdev =
> + pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> + PCI_ANY_ID, pdev)) != NULL)
> + vga_arbiter_add_pci_device(pdev);
> +
> + pr_info("vgaarb: loaded\n");
> + return rc;
> +}
> +subsys_initcall(vga_arb_device_init);
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index dbd0f94..d837606 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2502,6 +2502,50 @@ int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type)
> return 0;
> }
>
> +/**
> + * pci_set_vga_state - set VGA decode state on device and parents if requested
> + * @dev the PCI device
> + * @decode - true = enable decoding, false = disable decoding
> + * @command_bits PCI_COMMAND_IO and/or PCI_COMMAND_MEMORY
> + * @change_bridge - traverse ancestors and change bridges
> + */
> +int pci_set_vga_state(struct pci_dev *dev, bool decode,
> + unsigned int command_bits, bool change_bridge)
> +{
> + struct pci_bus *bus;
> + struct pci_dev *bridge;
> + u16 cmd;
> +
> + WARN_ON(command_bits & ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY));
> +
> + pci_read_config_word(dev, PCI_COMMAND, &cmd);
> + if (decode == true)
> + cmd |= command_bits;
> + else
> + cmd &= ~command_bits;
> + pci_write_config_word(dev, PCI_COMMAND, cmd);
> +
> + if (change_bridge == false)
> + return 0;
> +
> + bus = dev->bus;
> + while (bus) {
> + bridge = bus->self;
> + if (bridge) {
> + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
> + &cmd);
> + if (decode == true)
> + cmd |= PCI_BRIDGE_CTL_VGA;
> + else
> + cmd &= ~PCI_BRIDGE_CTL_VGA;
> + pci_write_config_word(bridge, PCI_BRIDGE_CONTROL,
> + cmd);
> + }
> + bus = bus->parent;
> + }
> + return 0;
> +}
> +
> #define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
> static char resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
> spinlock_t resource_alignment_lock = SPIN_LOCK_UNLOCKED;
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 3b54b39..a0d9ee1 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -7,6 +7,8 @@ menu "Graphics support"
>
> source "drivers/char/agp/Kconfig"
>
> +source "drivers/gpu/vga/Kconfig"
> +
> source "drivers/gpu/drm/Kconfig"
>
> config VGASTATE
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 115fb7b..7ba6eba 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -805,6 +805,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
> int pci_cfg_space_size(struct pci_dev *dev);
> unsigned char pci_bus_max_busnr(struct pci_bus *bus);
>
> +int pci_set_vga_state(struct pci_dev *pdev, bool decode,
> + unsigned int command_bits, bool change_bridge);
> /* kmem_cache style wrapper around pci_alloc_consistent() */
>
> #include <linux/dmapool.h>
> diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
> new file mode 100644
> index 0000000..68229ce
> --- /dev/null
> +++ b/include/linux/vgaarb.h
> @@ -0,0 +1,195 @@
> +/*
> + * vgaarb.c
^^^^^^^^
change to vgaarb.h
> + *
> + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
> + */
> +
> +#ifndef LINUX_VGA_H
> +
> +#include <asm/vga.h>
> +
> +/* Legacy VGA regions */
> +#define VGA_RSRC_NONE 0x00
> +#define VGA_RSRC_LEGACY_IO 0x01
> +#define VGA_RSRC_LEGACY_MEM 0x02
> +#define VGA_RSRC_LEGACY_MASK (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)
> +/* Non-legacy access */
> +#define VGA_RSRC_NORMAL_IO 0x04
> +#define VGA_RSRC_NORMAL_MEM 0x08
> +
> +/* Passing that instead of a pci_dev to use the system "default"
> + * device, that is the one used by vgacon. Archs will probably
> + * have to provide their own vga_default_device();
> + */
> +#define VGA_DEFAULT_DEVICE (NULL)
> +
> +/* For use by clients */
> +
> +/**
> + * vga_set_legacy_decoding
> + *
> + * @pdev: pci device of the VGA card
> + * @decodes: bit mask of what legacy regions the card decodes
> + *
> + * Indicates to the arbiter if the card decodes legacy VGA IOs,
> + * legacy VGA Memory, both, or none. All cards default to both,
> + * the card driver (fbdev for example) should tell the arbiter
> + * if it has disabled legacy decoding, so the card can be left
> + * out of the arbitration process (and can be safe to take
> + * interrupts at any time.
> + */
> +extern void vga_set_legacy_decoding(struct pci_dev *pdev,
> + unsigned int decodes);
> +
> +/**
> + * vga_get - acquire & locks VGA resources
> + *
> + * pdev: pci device of the VGA card or NULL for the system default
> + * rsrc: bit mask of resources to acquire and lock
> + * interruptible: blocking should be interruptible by signals ?
> + *
> + * This function acquires VGA resources for the given
> + * card and mark those resources locked. If the resource requested
> + * are "normal" (and not legacy) resources, the arbiter will first check
> + * wether the card is doing legacy decoding for that type of resource. If
> + * yes, the lock is "converted" into a legacy resource lock.
> + * The arbiter will first look for all VGA cards that might conflict
> + * and disable their IOs and/or Memory access, inlcuding VGA forwarding
> + * on P2P bridges if necessary, so that the requested resources can
> + * be used. Then, the card is marked as locking these resources and
> + * the IO and/or Memory accesse are enabled on the card (including
> + * VGA forwarding on parent P2P bridges if any).
> + * This function will block if some conflicting card is already locking
> + * one of the required resources (or any resource on a different bus
> + * segment, since P2P bridges don't differenciate VGA memory and IO
> + * afaik). You can indicate wether this blocking should be interruptible
> + * by a signal (for userland interface) or not.
> + * Must not be called at interrupt time or in atomic context.
> + * If the card already owns the resources, the function succeeds.
> + * Nested calls are supported (a per-resource counter is maintained)
> + */
> +
> +extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
> + int interruptible);
> +
> +/**
> + * vga_get_interruptible
> + *
> + * Shortcut to vga_get
> + */
> +
> +static inline int vga_get_interruptible(struct pci_dev *pdev,
> + unsigned int rsrc)
> +{
> + return vga_get(pdev, rsrc, 1);
> +}
> +
> +/**
> + * vga_get_interruptible
> + *
> + * Shortcut to vga_get
> + */
> +
> +static inline int vga_get_uninterruptible(struct pci_dev *pdev,
> + unsigned int rsrc)
> +{
> + return vga_get(pdev, rsrc, 0);
> +}
> +
> +/**
> + * vga_tryget - try to acquire & lock legacy VGA resources
> + *
> + * @pdev: pci devivce of VGA card or NULL for system default
> + * @rsrc: bit mask of resources to acquire and lock
> + *
> + * This function performs the same operation as vga_get(), but
> + * will return an error (-EBUSY) instead of blocking if the resources
> + * are already locked by another card. It can be called in any context
> + */
> +
> +extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
> +
> +/**
> + * vga_put - release lock on legacy VGA resources
> + *
> + * @pdev: pci device of VGA card or NULL for system default
> + * @rsrc: but mask of resource to release
> + *
> + * This function releases resources previously locked by vga_get()
> + * or vga_tryget(). The resources aren't disabled right away, so
> + * that a subsequence vga_get() on the same card will succeed
> + * immediately. Resources have a counter, so locks are only
> + * released if the counter reaches 0.
> + */
> +
> +extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
> +
> +
> +/**
> + * vga_default_device
> + *
> + * This can be defined by the platform. The default implementation
> + * is rather dumb and will probably only work properly on single
> + * vga card setups and/or x86 platforms.
> + *
> + * If your VGA default device is not PCI, you'll have to return
> + * NULL here. In this case, I assume it will not conflict with
> + * any PCI card. If this is not true, I'll have to define two archs
> + * hooks for enabling/disabling the VGA default device if that is
> + * possible. This may be a problem with real _ISA_ VGA cards, in
> + * addition to a PCI one. I don't know at this point how to deal
> + * with that card. Can theirs IOs be disabled at all ? If not, then
> + * I suppose it's a matter of having the proper arch hook telling
> + * us about it, so we basically never allow anybody to succeed a
> + * vga_get()...
> + */
> +
> +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> +extern struct pci_dev *vga_default_device(void);
> +#endif
> +
> +/**
> + * vga_conflicts
> + *
> + * Architectures should define this if they have several
> + * independant PCI domains that can afford concurrent VGA
> + * decoding
> + */
> +
> +#ifndef __ARCH_HAS_VGA_CONFLICT
> +static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
> +{
> + return 1;
> +}
> +#endif
> +
> +/*
> + * Register a client with the VGA arbitration logic
> + * return value: number of VGA devices in system.
> + *
> + * Clients have two callback mechanisms they can use.
> + * irq enable/disable callback -
> + * If a client can't disable its GPUs VGA resources, then we
> + * need to be able to ask it to turn off its irqs when we
> + * turn off its mem and io decoding.
> + * set_vga_decode
> + * If a client can disable its GPU VGA resource, it will
> + * get a callback from this to set the encode/decode state
> + *
> + * Clients with disable abilities should check the return value
> + * of this function and if the VGA device count is > 1, should
> + * disable VGA decoding resources.
> + *
> + * Rationale: we cannot disable VGA decode resources unconditionally
> + * some single GPU laptops seem to require ACPI or BIOS access to the
> + * VGA registers to control things like backlights etc.
> + * Hopefully newer multi-GPU laptops do something saner, and desktops
> + * won't have any special ACPI for this.
> + */
> +int vga_client_register(struct pci_dev *pdev, void *cookie,
> + void (*irq_set_state)(void *cookie, bool state),
> + unsigned int (*set_vga_decode)(void *cookie, bool state));
> +
> +#endif /* LINUX_VGA_H */
> --
> 1.6.0.6
Tiago
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH] vga: implements VGA arbitration on Linux
2009-08-16 15:17 ` Tiago Vignatti
@ 2009-08-17 17:37 ` Jesse Barnes
2009-09-12 15:02 ` [PATCH] PCI/VGA: fix header commentary Tiago Vignatti
0 siblings, 1 reply; 17+ messages in thread
From: Jesse Barnes @ 2009-08-17 17:37 UTC (permalink / raw)
To: tiago.vignatti
Cc: Dave Airlie, Dave Airlie, linux-kernel@vger.kernel.org,
dri-devel@lists.sf.net
Can you send a patch for this stuff? Maybe it could be rolled in with
a fix for the warnings...
Thanks,
Jesse
On Sun, 16 Aug 2009 18:17:46 +0300
Tiago Vignatti <tiago.vignatti@nokia.com> wrote:
>
> Hi Jesse,
>
> Just for completeness, there are some perfectionisms clean ups that I
> catch bellow.
>
>
> On Tue, Aug 11, 2009 at 07:52:06AM +0200, Dave Airlie wrote:
> > From: Tiago Vignatti <tiago.vignatti@nokia.com>
> >
> > Background:
> > Graphic devices are accessed through ranges in I/O or memory space.
> > While most modern devices allow relocation of such ranges, some
> > "Legacy" VGA devices implemented on PCI will typically have the
> > same "hard-decoded" addresses as they did on ISA. For more details
> > see "PCI Bus Binding to IEEE Std 1275-1994 Standard for Boot
> > (Initialization Configuration) Firmware Revision 2.1" Section 7,
> > Legacy Devices.
> >
> > The Resource Access Control (RAC) module inside the X server
> > currently does
>
> RAC already gone away. Finally!
>
>
> > the task of arbitration when more than one legacy device co-exists
> > on the same machine. But the problem happens when these devices are
> > trying to be accessed by different userspace clients (e.g. two
> > server in parallel). Their address assignments conflict. Therefore
> > an arbitration scheme _outside_ of the X server is needed to
> > control the sharing of these resources. This document
> ^^^^^^^^
> AFAIK a patch is not a
> document :)
>
>
> > introduces the operation of the VGA arbiter implemented for Linux
> > kernel.
> >
> > Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> > Signed-off-by: Dave Airlie <airlied@redhat.com>
> > ---
> > drivers/gpu/Makefile | 2 +-
> > drivers/gpu/vga/Kconfig | 10 +
> > drivers/gpu/vga/Makefile | 1 +
> > drivers/gpu/vga/vgaarb.c | 1206
> > ++++++++++++++++++++++++++++++++++++++++++++++
> > drivers/pci/pci.c | 44 ++ drivers/video/Kconfig | 2 +
> > include/linux/pci.h | 2 +
> > include/linux/vgaarb.h | 195 ++++++++
> > 8 files changed, 1461 insertions(+), 1 deletions(-)
> > create mode 100644 drivers/gpu/vga/Kconfig
> > create mode 100644 drivers/gpu/vga/Makefile
> > create mode 100644 drivers/gpu/vga/vgaarb.c
> > create mode 100644 include/linux/vgaarb.h
> >
> > diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
> > index de566cf..30879df 100644
> > --- a/drivers/gpu/Makefile
> > +++ b/drivers/gpu/Makefile
> > @@ -1 +1 @@
> > -obj-y += drm/
> > +obj-y += drm/ vga/
> > diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
> > new file mode 100644
> > index 0000000..790e675
> > --- /dev/null
> > +++ b/drivers/gpu/vga/Kconfig
> > @@ -0,0 +1,10 @@
> > +config VGA_ARB
> > + bool "VGA Arbitration" if EMBEDDED
> > + default y
> > + depends on PCI
> > + help
> > + Some "legacy" VGA devices implemented on PCI typically
> > have the same
> > + hard-decoded addresses as they did on ISA. When multiple
> > PCI devices
> > + are accessed at same time they need some kind of
> > coordination. Please
> > + see Documentation/vgaarbiter.txt for more details. Select
> > this to
> > + enable VGA arbiter.
> > diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
> > new file mode 100644
> > index 0000000..7cc8c1e
> > --- /dev/null
> > +++ b/drivers/gpu/vga/Makefile
> > @@ -0,0 +1 @@
> > +obj-$(CONFIG_VGA_ARB) += vgaarb.o
> > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > new file mode 100644
> > index 0000000..199138f
> > --- /dev/null
> > +++ b/drivers/gpu/vga/vgaarb.c
> > @@ -0,0 +1,1206 @@
> > +/*
> > + * vgaarb.c
> > + *
> > + * (C) Copyright 2005 Benjamin Herrenschmidt
> > <benh@kernel.crashing.org>
> > + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> > + * (C) Copyright 2007, 2009 Tiago Vignatti
> > <vignatti@freedesktop.org>
> > + *
> > + * Implements the VGA arbitration. For details refer to
> > + * Documentation/vgaarbiter.txt
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/pci.h>
> > +#include <linux/errno.h>
> > +#include <linux/init.h>
> > +#include <linux/list.h>
> > +#include <linux/sched.h>
> > +#include <linux/wait.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/poll.h>
> > +#include <linux/miscdevice.h>
> > +
> > +#include <linux/uaccess.h>
> > +
> > +#include <linux/vgaarb.h>
> > +
> > +static void vga_arbiter_notify_clients(void);
> > +/*
> > + * We keep a list of all vga devices in the system to speed
> > + * up the various operations of the arbiter
> > + */
> > +struct vga_device {
> > + struct list_head list;
> > + struct pci_dev *pdev;
> > + unsigned int decodes; /* what does it decodes */
> > + unsigned int owns; /* what does it owns */
> > + unsigned int locks; /* what does it locks */
> > + unsigned int io_lock_cnt; /* legacy IO lock count */
> > + unsigned int mem_lock_cnt; /* legacy MEM lock count */
> > + unsigned int io_norm_cnt; /* normal IO count */
> > + unsigned int mem_norm_cnt; /* normal MEM count */
> > +
> > + /* allow IRQ enable/disable hook */
> > + void *cookie;
> > + void (*irq_set_state)(void *cookie, bool enable);
> > + unsigned int (*set_vga_decode)(void *cookie, bool decode);
> > +};
> > +
> > +static LIST_HEAD(vga_list);
> > +static int vga_count, vga_decode_count;
> > +static bool vga_arbiter_used;
> > +static DEFINE_SPINLOCK(vga_lock);
> > +static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
> > +
> > +
> > +static const char *vga_iostate_to_str(unsigned int iostate)
> > +{
> > + /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
> > + iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> > + switch (iostate) {
> > + case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
> > + return "io+mem";
> > + case VGA_RSRC_LEGACY_IO:
> > + return "io";
> > + case VGA_RSRC_LEGACY_MEM:
> > + return "mem";
> > + }
> > + return "none";
> > +}
> > +
> > +static int vga_str_to_iostate(char *buf, int str_size, int
> > *io_state) +{
> > + /* we could in theory hand out locks on IO and mem
> > + * separately to userspace but it can cause deadlocks */
> > + if (strncmp(buf, "none", 4) == 0) {
> > + *io_state = VGA_RSRC_NONE;
> > + return 1;
> > + }
> > +
> > + /* XXX We're not chekcing the str_size! */
> > + if (strncmp(buf, "io+mem", 6) == 0)
> > + goto both;
> > + else if (strncmp(buf, "io", 2) == 0)
> > + goto both;
> > + else if (strncmp(buf, "mem", 3) == 0)
> > + goto both;
> > + return 0;
> > +both:
> > + *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> > + return 1;
> > +}
> > +
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > +/* this is only used a cookie - it should not be dereferenced */
> > +static struct pci_dev *vga_default;
> > +#endif
> > +
> > +static void vga_arb_device_card_gone(struct pci_dev *pdev);
> > +
> > +/* Find somebody in our list */
> > +static struct vga_device *vgadev_find(struct pci_dev *pdev)
> > +{
> > + struct vga_device *vgadev;
> > +
> > + list_for_each_entry(vgadev, &vga_list, list)
> > + if (pdev == vgadev->pdev)
> > + return vgadev;
> > + return NULL;
> > +}
> > +
> > +/* Returns the default VGA device (vgacon's babe) */
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > +struct pci_dev *vga_default_device(void)
> > +{
> > + return vga_default;
> > +}
> > +#endif
> > +
> > +static inline void vga_irq_set_state(struct vga_device *vgadev,
> > bool state) +{
> > + if (vgadev->irq_set_state)
> > + vgadev->irq_set_state(vgadev->cookie, state);
> > +}
> > +
> > +
> > +/* If we don't ever use VGA arb we should avoid
> > + turning off anything anywhere due to old X servers getting
> > + confused about the boot device not being VGA */
> > +static void vga_check_first_use(void)
> > +{
> > + /* we should inform all GPUs in the system that
> > + * VGA arb has occured and to try and disable resources
> > + * if they can */
> > + if (!vga_arbiter_used) {
> > + vga_arbiter_used = true;
> > + vga_arbiter_notify_clients();
> > + }
> > +}
> > +
> > +static struct vga_device *__vga_tryget(struct vga_device *vgadev,
> > + unsigned int rsrc)
> > +{
> > + unsigned int wants, legacy_wants, match;
> > + struct vga_device *conflict;
> > + unsigned int pci_bits;
> > + /* Account for "normal" resources to lock. If we decode the
> > legacy,
> > + * counterpart, we need to request it as well
> > + */
> > + if ((rsrc & VGA_RSRC_NORMAL_IO) &&
> > + (vgadev->decodes & VGA_RSRC_LEGACY_IO))
> > + rsrc |= VGA_RSRC_LEGACY_IO;
> > + if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
> > + (vgadev->decodes & VGA_RSRC_LEGACY_MEM))
> > + rsrc |= VGA_RSRC_LEGACY_MEM;
> > +
> > + pr_devel("%s: %d\n", __func__, rsrc);
> > + pr_devel("%s: owns: %d\n", __func__, vgadev->owns);
> > +
> > + /* Check what resources we need to acquire */
> > + wants = rsrc & ~vgadev->owns;
> > +
> > + /* We already own everything, just mark locked & bye bye */
> > + if (wants == 0)
> > + goto lock_them;
> > +
> > + /* We don't need to request a legacy resource, we just
> > enable
> > + * appropriate decoding and go
> > + */
> > + legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
> > + if (legacy_wants == 0)
> > + goto enable_them;
> > +
> > + /* Ok, we don't, let's find out how we need to kick off */
> > + list_for_each_entry(conflict, &vga_list, list) {
> > + unsigned int lwants = legacy_wants;
> > + unsigned int change_bridge = 0;
> > +
> > + /* Don't conflict with myself */
> > + if (vgadev == conflict)
> > + continue;
> > +
> > + /* Check if the architecture allows a conflict
> > between those
> > + * 2 devices or if they are on separate domains
> > + */
> > + if (!vga_conflicts(vgadev->pdev, conflict->pdev))
> > + continue;
> > +
> > + /* We have a possible conflict. before we go
> > further, we must
> > + * check if we sit on the same bus as the
> > conflicting device.
> > + * if we don't, then we must tie both IO and MEM
> > resources
> > + * together since there is only a single bit
> > controlling
> > + * VGA forwarding on P2P bridges
> > + */
> > + if (vgadev->pdev->bus != conflict->pdev->bus) {
> > + change_bridge = 1;
> > + lwants = VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM;
> > + }
> > +
> > + /* Check if the guy has a lock on the resource. If
> > he does,
> > + * return the conflicting entry
> > + */
> > + if (conflict->locks & lwants)
> > + return conflict;
> > +
> > + /* Ok, now check if he owns the resource we want.
> > We don't need
> > + * to check "decodes" since it should be impossible
> > to own
> > + * own legacy resources you don't decode unless I
> > have a bug
> > + * in this code...
> > + */
> > + WARN_ON(conflict->owns & ~conflict->decodes);
> > + match = lwants & conflict->owns;
> > + if (!match)
> > + continue;
> > +
> > + /* looks like he doesn't have a lock, we can steal
> > + * them from him
> > + */
> > + vga_irq_set_state(conflict, false);
> > +
> > + pci_bits = 0;
> > + if (lwants &
> > (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> > + pci_bits |= PCI_COMMAND_MEMORY;
> > + if (lwants &
> > (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> > + pci_bits |= PCI_COMMAND_IO;
> > +
> > + pci_set_vga_state(conflict->pdev, false, pci_bits,
> > + change_bridge);
> > + conflict->owns &= ~lwants;
> > + /* If he also owned non-legacy, that is no longer
> > the case */
> > + if (lwants & VGA_RSRC_LEGACY_MEM)
> > + conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
> > + if (lwants & VGA_RSRC_LEGACY_IO)
> > + conflict->owns &= ~VGA_RSRC_NORMAL_IO;
> > + }
> > +
> > +enable_them:
> > + /* ok dude, we got it, everybody conflicting has been
> > disabled, let's
> > + * enable us. Make sure we don't mark a bit in "owns" that
> > we don't
> > + * also have in "decodes". We can lock resources we don't
> > decode but
> > + * not own them.
> > + */
> > + pci_bits = 0;
> > + if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> > + pci_bits |= PCI_COMMAND_MEMORY;
> > + if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> > + pci_bits |= PCI_COMMAND_IO;
> > + pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants &
> > VGA_RSRC_LEGACY_MASK)); +
> > + vga_irq_set_state(vgadev, true);
> > + vgadev->owns |= (wants & vgadev->decodes);
> > +lock_them:
> > + vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
> > + if (rsrc & VGA_RSRC_LEGACY_IO)
> > + vgadev->io_lock_cnt++;
> > + if (rsrc & VGA_RSRC_LEGACY_MEM)
> > + vgadev->mem_lock_cnt++;
> > + if (rsrc & VGA_RSRC_NORMAL_IO)
> > + vgadev->io_norm_cnt++;
> > + if (rsrc & VGA_RSRC_NORMAL_MEM)
> > + vgadev->mem_norm_cnt++;
> > +
> > + return NULL;
> > +}
> > +
> > +static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
> > +{
> > + unsigned int old_locks = vgadev->locks;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + /* Update our counters, and account for equivalent legacy
> > resources
> > + * if we decode them
> > + */
> > + if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0)
> > {
> > + vgadev->io_norm_cnt--;
> > + if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
> > + rsrc |= VGA_RSRC_LEGACY_IO;
> > + }
> > + if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt >
> > 0) {
> > + vgadev->mem_norm_cnt--;
> > + if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
> > + rsrc |= VGA_RSRC_LEGACY_MEM;
> > + }
> > + if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
> > + vgadev->io_lock_cnt--;
> > + if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt >
> > 0)
> > + vgadev->mem_lock_cnt--;
> > +
> > + /* Just clear lock bits, we do lazy operations so we don't
> > really
> > + * have to bother about anything else at this point
> > + */
> > + if (vgadev->io_lock_cnt == 0)
> > + vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
> > + if (vgadev->mem_lock_cnt == 0)
> > + vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
> > +
> > + /* Kick the wait queue in case somebody was waiting if we
> > actually
> > + * released something
> > + */
> > + if (old_locks != vgadev->locks)
> > + wake_up_all(&vga_wait_queue);
> > +}
> > +
> > +int vga_get(struct pci_dev *pdev, unsigned int rsrc, int
> > interruptible) +{
> > + struct vga_device *vgadev, *conflict;
> > + unsigned long flags;
> > + wait_queue_t wait;
> > + int rc = 0;
> > +
> > + vga_check_first_use();
> > + /* The one who calls us should check for this, but lets be
> > sure... */
> > + if (pdev == NULL)
> > + pdev = vga_default_device();
> > + if (pdev == NULL)
> > + return 0;
> > +
> > + for (;;) {
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + rc = -ENODEV;
> > + break;
> > + }
> > + conflict = __vga_tryget(vgadev, rsrc);
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + if (conflict == NULL)
> > + break;
> > +
> > +
> > + /* We have a conflict, we wait until somebody kicks
> > the
> > + * work queue. Currently we have one work queue
> > that we
> > + * kick each time some resources are released, but
> > it would
> > + * be fairly easy to have a per device one so that
> > we only
> > + * need to attach to the conflicting device
> > + */
> > + init_waitqueue_entry(&wait, current);
> > + add_wait_queue(&vga_wait_queue, &wait);
> > + set_current_state(interruptible ?
> > + TASK_INTERRUPTIBLE :
> > + TASK_UNINTERRUPTIBLE);
> > + if (signal_pending(current)) {
> > + rc = -EINTR;
> > + break;
> > + }
> > + schedule();
> > + remove_wait_queue(&vga_wait_queue, &wait);
> > + set_current_state(TASK_RUNNING);
> > + }
> > + return rc;
> > +}
> > +EXPORT_SYMBOL(vga_get);
> > +
> > +int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
> > +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > + int rc = 0;
> > +
> > + vga_check_first_use();
> > +
> > + /* The one who calls us should check for this, but lets be
> > sure... */
> > + if (pdev == NULL)
> > + pdev = vga_default_device();
> > + if (pdev == NULL)
> > + return 0;
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + rc = -ENODEV;
> > + goto bail;
> > + }
> > + if (__vga_tryget(vgadev, rsrc))
> > + rc = -EBUSY;
> > +bail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + return rc;
> > +}
> > +EXPORT_SYMBOL(vga_tryget);
> > +
> > +void vga_put(struct pci_dev *pdev, unsigned int rsrc)
> > +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > +
> > + /* The one who calls us should check for this, but lets be
> > sure... */
> > + if (pdev == NULL)
> > + pdev = vga_default_device();
> > + if (pdev == NULL)
> > + return;
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL)
> > + goto bail;
> > + __vga_put(vgadev, rsrc);
> > +bail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > +}
> > +EXPORT_SYMBOL(vga_put);
> > +
> > +/*
> > + * Currently, we assume that the "initial" setup of the system is
> > + * not sane, that is we come up with conflicting devices and let
> > + * the arbiter's client decides if devices decodes or not legacy
> > + * things.
> > + */
> > +static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> > +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > + struct pci_bus *bus;
> > + struct pci_dev *bridge;
> > + u16 cmd;
> > +
> > + /* Only deal with VGA class devices */
> > + if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> > + return false;
> > +
> > + /* Allocate structure */
> > + vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
> > + if (vgadev == NULL) {
> > + pr_err("vgaarb: failed to allocate pci device\n");
> > + /* What to do on allocation failure ? For now, let's
> > + * just do nothing, I'm not sure there is anything
> > saner
> > + * to be done
> > + */
> > + return false;
> > + }
> > +
> > + memset(vgadev, 0, sizeof(*vgadev));
> > +
> > + /* Take lock & check for duplicates */
> > + spin_lock_irqsave(&vga_lock, flags);
> > + if (vgadev_find(pdev) != NULL) {
> > + BUG_ON(1);
> > + goto fail;
> > + }
> > + vgadev->pdev = pdev;
> > +
> > + /* By default, assume we decode everything */
> > + vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
> > + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
> > +
> > + /* by default mark it as decoding */
> > + vga_decode_count++;
> > + /* Mark that we "own" resources based on our enables, we
> > will
> > + * clear that below if the bridge isn't forwarding
> > + */
> > + pci_read_config_word(pdev, PCI_COMMAND, &cmd);
> > + if (cmd & PCI_COMMAND_IO)
> > + vgadev->owns |= VGA_RSRC_LEGACY_IO;
> > + if (cmd & PCI_COMMAND_MEMORY)
> > + vgadev->owns |= VGA_RSRC_LEGACY_MEM;
> > +
> > + /* Check if VGA cycles can get down to us */
> > + bus = pdev->bus;
> > + while (bus) {
> > + bridge = bus->self;
> > + if (bridge) {
> > + u16 l;
> > + pci_read_config_word(bridge,
> > PCI_BRIDGE_CONTROL,
> > + &l);
> > + if (!(l & PCI_BRIDGE_CTL_VGA)) {
> > + vgadev->owns = 0;
> > + break;
> > + }
> > + }
> > + bus = bus->parent;
> > + }
> > +
> > + /* Deal with VGA default device. Use first enabled one
> > + * by default if arch doesn't have it's own hook
> > + */
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > + if (vga_default == NULL &&
> > + ((vgadev->owns & VGA_RSRC_LEGACY_MASK) ==
> > VGA_RSRC_LEGACY_MASK))
> > + vga_default = pci_dev_get(pdev);
> > +#endif
> > +
> > + /* Add to the list */
> > + list_add(&vgadev->list, &vga_list);
> > + vga_count++;
> > + pr_info("vgaarb: device added:
> > PCI:%s,decodes=%s,owns=%s,locks=%s\n",
> > + pci_name(pdev),
> > + vga_iostate_to_str(vgadev->decodes),
> > + vga_iostate_to_str(vgadev->owns),
> > + vga_iostate_to_str(vgadev->locks));
> > +
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + return true;
> > +fail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + kfree(vgadev);
> > + return false;
> > +}
> > +
> > +static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
> > +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > + bool ret = true;
> > +
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + ret = false;
> > + goto bail;
> > + }
> > +
> > + if (vga_default == pdev) {
> > + pci_dev_put(vga_default);
> > + vga_default = NULL;
> > + }
> > +
> > + if (vgadev->decodes & (VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM))
> > + vga_decode_count--;
> > +
> > + /* Remove entry from list */
> > + list_del(&vgadev->list);
> > + vga_count--;
> > + /* Notify userland driver that the device is gone so it
> > discards
> > + * it's copies of the pci_dev pointer
> > + */
> > + vga_arb_device_card_gone(pdev);
> > +
> > + /* Wake up all possible waiters */
> > + wake_up_all(&vga_wait_queue);
> > +bail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + kfree(vgadev);
> > + return ret;
> > +}
> > +
> > +/* this is called with the lock */
> > +static inline void vga_update_device_decodes(struct vga_device
> > *vgadev,
> > + int new_decodes)
> > +{
> > + int old_decodes;
> > + struct vga_device *new_vgadev, *conflict;
> > +
> > + old_decodes = vgadev->decodes;
> > + vgadev->decodes = new_decodes;
> > +
> > + pr_info("vgaarb: device changed decodes:
> > PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
> > + pci_name(vgadev->pdev),
> > + vga_iostate_to_str(old_decodes),
> > + vga_iostate_to_str(vgadev->decodes),
> > + vga_iostate_to_str(vgadev->owns));
> > +
> > +
> > + /* if we own the decodes we should move them along to
> > + another card */
> > + if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
> > + /* set us to own nothing */
> > + vgadev->owns &= ~old_decodes;
> > + list_for_each_entry(new_vgadev, &vga_list, list) {
> > + if ((new_vgadev != vgadev) &&
> > + (new_vgadev->decodes &
> > VGA_RSRC_LEGACY_MASK)) {
> > + pr_info("vgaarb: transferring owner
> > from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev),
> > pci_name(new_vgadev->pdev));
> > + conflict = __vga_tryget(new_vgadev,
> > VGA_RSRC_LEGACY_MASK);
> > + if (!conflict)
> > + __vga_put(new_vgadev,
> > VGA_RSRC_LEGACY_MASK);
> > + break;
> > + }
> > + }
> > + }
> > +
> > + /* change decodes counter */
> > + if (old_decodes != new_decodes) {
> > + if (new_decodes & (VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM))
> > + vga_decode_count++;
> > + else
> > + vga_decode_count--;
> > + }
> > +}
> > +
> > +void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int
> > decodes, bool userspace) +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > +
> > + decodes &= VGA_RSRC_LEGACY_MASK;
> > +
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL)
> > + goto bail;
> > +
> > + /* don't let userspace futz with kernel driver decodes */
> > + if (userspace && vgadev->set_vga_decode)
> > + goto bail;
> > +
> > + /* update the device decodes + counter */
> > + vga_update_device_decodes(vgadev, decodes);
> > +
> > + /* XXX if somebody is going from "doesn't decode" to
> > "decodes" state
> > + * here, additional care must be taken as we may have
> > pending owner
> > + * ship of non-legacy region ...
> > + */
> > +bail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > +}
> > +
> > +void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int
> > decodes) +{
> > + __vga_set_legacy_decoding(pdev, decodes, false);
> > +}
> > +EXPORT_SYMBOL(vga_set_legacy_decoding);
> > +
> > +/* return number of active VGA devices */
> > +/* call with NULL to unregister */
> > +int vga_client_register(struct pci_dev *pdev, void *cookie,
> > + void (*irq_set_state)(void *cookie, bool
> > state),
> > + unsigned int (*set_vga_decode)(void
> > *cookie, bool decode)) +{
> > + int ret = -1;
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (!vgadev)
> > + goto bail;
> > +
> > + vgadev->irq_set_state = irq_set_state;
> > + vgadev->set_vga_decode = set_vga_decode;
> > + vgadev->cookie = cookie;
> > + ret = 0;
> > +
> > +bail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + return ret;
> > +
> > +}
> > +EXPORT_SYMBOL(vga_client_register);
> > +
> > +/*
> > + * Char driver implementation
> > + *
> > + * Semantics is:
> > + *
> > + * open : open user instance of the arbitrer. by default,
> > it's
> > + * attached to the default VGA device of the system.
> > + *
> > + * close : close user instance, release locks
> > + *
> > + * read : return a string indicating the status of the
> > target.
> > + * an IO state string is of the form
> > {io,mem,io+mem,none},
> > + * mc and ic are respectively mem and io lock
> > counts (for
> > + * debugging/diagnostic only). "decodes" indicate
> > what the
> > + * card currently decodes, "owns" indicates what is
> > currently
> > + * enabled on it, and "locks" indicates what is
> > locked by this
> > + * card. If the card is unplugged, we get "invalid"
> > then for
> > + * card_ID and an -ENODEV error is returned for any
> > command
> > + * until a new card is targeted
> > + *
> > + *
> > "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state>
> > (ic,mc)"
> > + *
> > + * write : write a command to the arbiter. List of commands
> > is:
> > + *
> > + * target <card_ID> : switch target to card <card_ID> (see
> > below)
> > + * lock <io_state> : acquires locks on target ("none" is
> > invalid io_state)
> > + * trylock <io_state> : non-blocking acquire locks on target
> > + * unlock <io_state> : release locks on target
> > + * unlock all : release all locks on target held by this
> > user
> > + * decodes <io_state> : set the legacy decoding attributes for
> > the card
> > + *
> > + * poll : event if something change on any card (not just
> > the target)
> > + *
> > + * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set
> > to "default"
> > + * to go back to the system default card (TODO: not implemented
> > yet).
> > + * Currently, only PCI is supported as a prefix, but the userland
> > API may
> > + * support other bus types in the future, even if the current
> > kernel
> > + * implementation doesn't.
> > + *
> > + * Note about locks:
> > + *
> > + * The driver keeps track of which user has what locks on which
> > card. It
> > + * supports stacking, like the kernel one. This complexifies the
> > implementation
> > + * a bit, but makes the arbiter more tolerant to userspace
> > problems and able
> > + * to properly cleanup in all cases when a process dies.
> > + * Currently, a max of 16 cards simultaneously can have locks
> > issued from
> > + * userspace for a given user (file descriptor instance) of the
> > arbiter.
> > + *
> > + * If the device is hot-unplugged, there is a hook inside the
> > module to notify
> > + * they being added/removed in the system and automatically
> > added/removed in
> > + * the arbiter.
> > + */
> > +
> > +#define MAX_USER_CARDS 16
> > +#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
> > +
> > +/*
> > + * Each user has an array of these, tracking which cards have locks
> > + */
> > +struct vga_arb_user_card {
> > + struct pci_dev *pdev;
> > + unsigned int mem_cnt;
> > + unsigned int io_cnt;
> > +};
> > +
> > +struct vga_arb_private {
> > + struct list_head list;
> > + struct pci_dev *target;
> > + struct vga_arb_user_card cards[MAX_USER_CARDS];
> > + spinlock_t lock;
> > +};
> > +
> > +static LIST_HEAD(vga_user_list);
> > +static DEFINE_SPINLOCK(vga_user_lock);
> > +
> > +
> > +/*
> > + * This function gets a string in the format:
> > "PCI:domain:bus:dev.fn" and
> > + * returns the respective values. If the string is not in this
> > format,
> > + * it returns 0.
> > + */
> > +static int vga_pci_str_to_vars(char *buf, int count, unsigned int
> > *domain,
> > + unsigned int *bus, unsigned int
> > *devfn) +{
> > + int n;
> > + unsigned int slot, func;
> > +
> > +
> > + n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot,
> > &func);
> > + if (n != 4)
> > + return 0;
> > +
> > + *devfn = PCI_DEVFN(slot, func);
> > +
> > + return 1;
> > +}
> > +
> > +static ssize_t vga_arb_read(struct file *file, char __user * buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + struct vga_arb_private *priv = file->private_data;
> > + struct vga_device *vgadev;
> > + struct pci_dev *pdev;
> > + unsigned long flags;
> > + size_t len;
> > + int rc;
> > + char *lbuf;
> > +
> > + lbuf = kmalloc(1024, GFP_KERNEL);
> > + if (lbuf == NULL)
> > + return -ENOMEM;
> > +
> > + /* Shields against vga_arb_device_card_gone (pci_dev going
> > + * away), and allows access to vga list
> > + */
> > + spin_lock_irqsave(&vga_lock, flags);
> > +
> > + /* If we are targetting the default, use it */
> > + pdev = priv->target;
> > + if (pdev == NULL || pdev == PCI_INVALID_CARD) {
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + len = sprintf(lbuf, "invalid");
> > + goto done;
> > + }
> > +
> > + /* Find card vgadev structure */
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + /* Wow, it's not in the list, that shouldn't happen,
> > + * let's fix us up and return invalid card
> > + */
> > + if (pdev == priv->target)
> > + vga_arb_device_card_gone(pdev);
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + len = sprintf(lbuf, "invalid");
> > + goto done;
> > + }
> > +
> > + /* Fill the buffer with infos */
> > + len = snprintf(lbuf, 1024,
> > +
> > "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
> > + vga_decode_count, pci_name(pdev),
> > + vga_iostate_to_str(vgadev->decodes),
> > + vga_iostate_to_str(vgadev->owns),
> > + vga_iostate_to_str(vgadev->locks),
> > + vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
> > +
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > +done:
> > +
> > + /* Copy that to user */
> > + if (len > count)
> > + len = count;
> > + rc = copy_to_user(buf, lbuf, len);
> > + kfree(lbuf);
> > + if (rc)
> > + return -EFAULT;
> > + return len;
> > +}
> > +
> > +/*
> > + * TODO: To avoid parsing inside kernel and to improve the speed
> > we may
> > + * consider use ioctl here
> > + */
> > +static ssize_t vga_arb_write(struct file *file, const char __user
> > * buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + struct vga_arb_private *priv = file->private_data;
> > + struct vga_arb_user_card *uc = NULL;
> > + struct pci_dev *pdev;
> > +
> > + unsigned int io_state;
> > +
> > + char *kbuf, *curr_pos;
> > + size_t remaining = count;
> > +
> > + int ret_val;
> > + int i;
> > +
> > +
> > + kbuf = kmalloc(count + 1, GFP_KERNEL);
> > + if (!kbuf)
> > + return -ENOMEM;
> > +
> > + if (copy_from_user(kbuf, buf, count)) {
> > + kfree(kbuf);
> > + return -EFAULT;
> > + }
> > + curr_pos = kbuf;
> > + kbuf[count] = '\0'; /* Just to make sure... */
> > +
> > + if (strncmp(curr_pos, "lock ", 5) == 0) {
> > + curr_pos += 5;
> > + remaining -= 5;
> > +
> > + pr_devel("client 0x%X called 'lock'\n", (int)priv);
> > +
> > + if (!vga_str_to_iostate(curr_pos, remaining,
> > &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + if (io_state == VGA_RSRC_NONE) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > +
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + vga_get_uninterruptible(pdev, io_state);
> > +
> > + /* Update the client's locks lists... */
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev) {
> > + if (io_state & VGA_RSRC_LEGACY_IO)
> > + priv->cards[i].io_cnt++;
> > + if (io_state & VGA_RSRC_LEGACY_MEM)
> > + priv->cards[i].mem_cnt++;
> > + break;
> > + }
> > + }
> > +
> > + ret_val = count;
> > + goto done;
> > + } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
> > + curr_pos += 7;
> > + remaining -= 7;
> > +
> > + pr_devel("client 0x%X called 'unlock'\n",
> > (int)priv); +
> > + if (strncmp(curr_pos, "all", 3) == 0)
> > + io_state = VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM;
> > + else {
> > + if (!vga_str_to_iostate
> > + (curr_pos, remaining, &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + /* TODO: Add this?
> > + if (io_state == VGA_RSRC_NONE) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + */
> > + }
> > +
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev)
> > + uc = &priv->cards[i];
> > + }
> > +
> > + if (!uc)
> > + return -EINVAL;
> > +
> > + if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt ==
> > 0)
> > + return -EINVAL;
> > +
> > + if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt
> > == 0)
> > + return -EINVAL;
> > +
> > + vga_put(pdev, io_state);
> > +
> > + if (io_state & VGA_RSRC_LEGACY_IO)
> > + uc->io_cnt--;
> > + if (io_state & VGA_RSRC_LEGACY_MEM)
> > + uc->mem_cnt--;
> > +
> > + ret_val = count;
> > + goto done;
> > + } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
> > + curr_pos += 8;
> > + remaining -= 8;
> > +
> > + pr_devel("client 0x%X called 'trylock'\n",
> > (int)priv); +
> > + if (!vga_str_to_iostate(curr_pos, remaining,
> > &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + /* TODO: Add this?
> > + if (io_state == VGA_RSRC_NONE) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + */
> > +
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + if (vga_tryget(pdev, io_state)) {
> > + /* Update the client's locks lists... */
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev) {
> > + if (io_state &
> > VGA_RSRC_LEGACY_IO)
> > +
> > priv->cards[i].io_cnt++;
> > + if (io_state &
> > VGA_RSRC_LEGACY_MEM)
> > +
> > priv->cards[i].mem_cnt++;
> > + break;
> > + }
> > + }
> > + ret_val = count;
> > + goto done;
> > + } else {
> > + ret_val = -EBUSY;
> > + goto done;
> > + }
> > +
> > + } else if (strncmp(curr_pos, "target ", 7) == 0) {
> > + unsigned int domain, bus, devfn;
> > + struct vga_device *vgadev;
> > +
> > + curr_pos += 7;
> > + remaining -= 7;
> > + pr_devel("client 0x%X called 'target'\n",
> > (int)priv);
> > + /* if target is default */
> > + if (!strncmp(buf, "default", 7))
> > + pdev = pci_dev_get(vga_default_device());
> > + else {
> > + if (!vga_pci_str_to_vars(curr_pos,
> > remaining,
> > + &domain, &bus,
> > &devfn)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > +
> > + pdev = pci_get_bus_and_slot(bus, devfn);
> > + if (!pdev) {
> > + pr_info("vgaarb: invalid PCI
> > address!\n");
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > + }
> > +
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + pr_info("vgaarb: this pci device is not a
> > vga device\n");
> > + pci_dev_put(pdev);
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + priv->target = pdev;
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev)
> > + break;
> > + if (priv->cards[i].pdev == NULL) {
> > + priv->cards[i].pdev = pdev;
> > + priv->cards[i].io_cnt = 0;
> > + priv->cards[i].mem_cnt = 0;
> > + break;
> > + }
> > + }
> > + if (i == MAX_USER_CARDS) {
> > + pr_err("vgaarb: maximum user cards number
> > reached!\n");
> > + pci_dev_put(pdev);
> > + /* XXX: which value to return? */
> > + ret_val = -ENOMEM;
> > + goto done;
> > + }
> > +
> > + ret_val = count;
> > + pci_dev_put(pdev);
> > + goto done;
> > +
> > +
> > + } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
> > + curr_pos += 8;
> > + remaining -= 8;
> > + pr_devel("vgaarb: client 0x%X called 'decodes'\n",
> > (int)priv); +
> > + if (!vga_str_to_iostate(curr_pos, remaining,
> > &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + __vga_set_legacy_decoding(pdev, io_state, true);
> > + ret_val = count;
> > + goto done;
> > + }
> > + /* If we got here, the message written is not part of the
> > protocol! */
> > + kfree(kbuf);
> > + return -EPROTO;
> > +
> > +done:
> > + kfree(kbuf);
> > + return ret_val;
> > +}
> > +
> > +static unsigned int vga_arb_fpoll(struct file *file, poll_table *
> > wait) +{
> > + struct vga_arb_private *priv = file->private_data;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + if (priv == NULL)
> > + return -ENODEV;
> > + poll_wait(file, &vga_wait_queue, wait);
> > + return POLLIN;
> > +}
> > +
> > +static int vga_arb_open(struct inode *inode, struct file *file)
> > +{
> > + struct vga_arb_private *priv;
> > + unsigned long flags;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
> > + if (priv == NULL)
> > + return -ENOMEM;
> > + memset(priv, 0, sizeof(*priv));
> > + spin_lock_init(&priv->lock);
> > + file->private_data = priv;
> > +
> > + spin_lock_irqsave(&vga_user_lock, flags);
> > + list_add(&priv->list, &vga_user_list);
> > + spin_unlock_irqrestore(&vga_user_lock, flags);
> > +
> > + /* Set the client' lists of locks */
> > + priv->target = vga_default_device(); /* Maybe this is still
> > null! */
> > + priv->cards[0].pdev = priv->target;
> > + priv->cards[0].io_cnt = 0;
> > + priv->cards[0].mem_cnt = 0;
> > +
> > +
> > + return 0;
> > +}
> > +
> > +static int vga_arb_release(struct inode *inode, struct file *file)
> > +{
> > + struct vga_arb_private *priv = file->private_data;
> > + struct vga_arb_user_card *uc;
> > + unsigned long flags;
> > + int i;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + if (priv == NULL)
> > + return -ENODEV;
> > +
> > + spin_lock_irqsave(&vga_user_lock, flags);
> > + list_del(&priv->list);
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + uc = &priv->cards[i];
> > + if (uc->pdev == NULL)
> > + continue;
> > + pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
> > + uc->io_cnt, uc->mem_cnt);
> > + while (uc->io_cnt--)
> > + vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
> > + while (uc->mem_cnt--)
> > + vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
> > + }
> > + spin_unlock_irqrestore(&vga_user_lock, flags);
> > +
> > + kfree(priv);
> > +
> > + return 0;
> > +}
> > +
> > +static void vga_arb_device_card_gone(struct pci_dev *pdev)
> > +{
> > +}
> > +
> > +/*
> > + * callback any registered clients to let them know we have a
> > + * change in VGA cards
> > + */
> > +static void vga_arbiter_notify_clients(void)
> > +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > + uint32_t new_decodes;
> > + bool new_state;
> > +
> > + if (!vga_arbiter_used)
> > + return;
> > +
> > + spin_lock_irqsave(&vga_lock, flags);
> > + list_for_each_entry(vgadev, &vga_list, list) {
> > + if (vga_count > 1)
> > + new_state = false;
> > + else
> > + new_state = true;
> > + if (vgadev->set_vga_decode) {
> > + new_decodes =
> > vgadev->set_vga_decode(vgadev->cookie, new_state);
> > + vga_update_device_decodes(vgadev,
> > new_decodes);
> > + }
> > + }
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > +}
> > +
> > +static int pci_notify(struct notifier_block *nb, unsigned long
> > action,
> > + void *data)
> > +{
> > + struct device *dev = data;
> > + struct pci_dev *pdev = to_pci_dev(dev);
> > + bool notify = false;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + /* For now we're only intereted in devices added and
> > removed. I didn't
> > + * test this thing here, so someone needs to double check
> > for the
> > + * cases of hotplugable vga cards. */
> > + if (action == BUS_NOTIFY_ADD_DEVICE)
> > + notify = vga_arbiter_add_pci_device(pdev);
> > + else if (action == BUS_NOTIFY_DEL_DEVICE)
> > + notify = vga_arbiter_del_pci_device(pdev);
> > +
> > + if (notify)
> > + vga_arbiter_notify_clients();
> > + return 0;
> > +}
> > +
> > +static struct notifier_block pci_notifier = {
> > + .notifier_call = pci_notify,
> > +};
> > +
> > +static const struct file_operations vga_arb_device_fops = {
> > + .read = vga_arb_read,
> > + .write = vga_arb_write,
> > + .poll = vga_arb_fpoll,
> > + .open = vga_arb_open,
> > + .release = vga_arb_release,
> > +};
> > +
> > +static struct miscdevice vga_arb_device = {
> > + MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> > +};
> > +
> > +static int __init vga_arb_device_init(void)
> > +{
> > + int rc;
> > + struct pci_dev *pdev;
> > +
> > + rc = misc_register(&vga_arb_device);
> > + if (rc < 0)
> > + pr_err("vgaarb: error %d registering device\n", rc);
> > +
> > + bus_register_notifier(&pci_bus_type, &pci_notifier);
> > +
> > + /* We add all pci devices satisfying vga class in the
> > arbiter by
> > + * default */
> > + pdev = NULL;
> > + while ((pdev =
> > + pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> > + PCI_ANY_ID, pdev)) != NULL)
> > + vga_arbiter_add_pci_device(pdev);
> > +
> > + pr_info("vgaarb: loaded\n");
> > + return rc;
> > +}
> > +subsys_initcall(vga_arb_device_init);
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index dbd0f94..d837606 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -2502,6 +2502,50 @@ int pci_resource_bar(struct pci_dev *dev,
> > int resno, enum pci_bar_type *type) return 0;
> > }
> >
> > +/**
> > + * pci_set_vga_state - set VGA decode state on device and parents
> > if requested
> > + * @dev the PCI device
> > + * @decode - true = enable decoding, false = disable decoding
> > + * @command_bits PCI_COMMAND_IO and/or PCI_COMMAND_MEMORY
> > + * @change_bridge - traverse ancestors and change bridges
> > + */
> > +int pci_set_vga_state(struct pci_dev *dev, bool decode,
> > + unsigned int command_bits, bool change_bridge)
> > +{
> > + struct pci_bus *bus;
> > + struct pci_dev *bridge;
> > + u16 cmd;
> > +
> > + WARN_ON(command_bits &
> > ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY)); +
> > + pci_read_config_word(dev, PCI_COMMAND, &cmd);
> > + if (decode == true)
> > + cmd |= command_bits;
> > + else
> > + cmd &= ~command_bits;
> > + pci_write_config_word(dev, PCI_COMMAND, cmd);
> > +
> > + if (change_bridge == false)
> > + return 0;
> > +
> > + bus = dev->bus;
> > + while (bus) {
> > + bridge = bus->self;
> > + if (bridge) {
> > + pci_read_config_word(bridge,
> > PCI_BRIDGE_CONTROL,
> > + &cmd);
> > + if (decode == true)
> > + cmd |= PCI_BRIDGE_CTL_VGA;
> > + else
> > + cmd &= ~PCI_BRIDGE_CTL_VGA;
> > + pci_write_config_word(bridge,
> > PCI_BRIDGE_CONTROL,
> > + cmd);
> > + }
> > + bus = bus->parent;
> > + }
> > + return 0;
> > +}
> > +
> > #define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
> > static char
> > resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
> > spinlock_t resource_alignment_lock = SPIN_LOCK_UNLOCKED; diff --git
> > a/drivers/video/Kconfig b/drivers/video/Kconfig index
> > 3b54b39..a0d9ee1 100644 --- a/drivers/video/Kconfig
> > +++ b/drivers/video/Kconfig
> > @@ -7,6 +7,8 @@ menu "Graphics support"
> >
> > source "drivers/char/agp/Kconfig"
> >
> > +source "drivers/gpu/vga/Kconfig"
> > +
> > source "drivers/gpu/drm/Kconfig"
> >
> > config VGASTATE
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 115fb7b..7ba6eba 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -805,6 +805,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
> > int pci_cfg_space_size(struct pci_dev *dev);
> > unsigned char pci_bus_max_busnr(struct pci_bus *bus);
> >
> > +int pci_set_vga_state(struct pci_dev *pdev, bool decode,
> > + unsigned int command_bits, bool
> > change_bridge); /* kmem_cache style wrapper around
> > pci_alloc_consistent() */
> >
> > #include <linux/dmapool.h>
> > diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
> > new file mode 100644
> > index 0000000..68229ce
> > --- /dev/null
> > +++ b/include/linux/vgaarb.h
> > @@ -0,0 +1,195 @@
> > +/*
> > + * vgaarb.c
> ^^^^^^^^
> change to vgaarb.h
>
> > + *
> > + * (C) Copyright 2005 Benjamin Herrenschmidt
> > <benh@kernel.crashing.org>
> > + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
> > + * (C) Copyright 2007, 2009 Tiago Vignatti
> > <vignatti@freedesktop.org>
> > + */
> > +
> > +#ifndef LINUX_VGA_H
> > +
> > +#include <asm/vga.h>
> > +
> > +/* Legacy VGA regions */
> > +#define VGA_RSRC_NONE 0x00
> > +#define VGA_RSRC_LEGACY_IO 0x01
> > +#define VGA_RSRC_LEGACY_MEM 0x02
> > +#define VGA_RSRC_LEGACY_MASK (VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM) +/* Non-legacy access */
> > +#define VGA_RSRC_NORMAL_IO 0x04
> > +#define VGA_RSRC_NORMAL_MEM 0x08
> > +
> > +/* Passing that instead of a pci_dev to use the system "default"
> > + * device, that is the one used by vgacon. Archs will probably
> > + * have to provide their own vga_default_device();
> > + */
> > +#define VGA_DEFAULT_DEVICE (NULL)
> > +
> > +/* For use by clients */
> > +
> > +/**
> > + * vga_set_legacy_decoding
> > + *
> > + * @pdev: pci device of the VGA card
> > + * @decodes: bit mask of what legacy regions the card decodes
> > + *
> > + * Indicates to the arbiter if the card decodes legacy VGA IOs,
> > + * legacy VGA Memory, both, or none. All cards default to both,
> > + * the card driver (fbdev for example) should tell the arbiter
> > + * if it has disabled legacy decoding, so the card can be left
> > + * out of the arbitration process (and can be safe to take
> > + * interrupts at any time.
> > + */
> > +extern void vga_set_legacy_decoding(struct pci_dev *pdev,
> > +
> > unsigned int decodes); +
> > +/**
> > + * vga_get - acquire & locks VGA resources
> > + *
> > + * pdev: pci device of the VGA card or NULL for the system
> > default
> > + * rsrc: bit mask of resources to acquire and lock
> > + * interruptible: blocking should be interruptible by signals ?
> > + *
> > + * This function acquires VGA resources for the given
> > + * card and mark those resources locked. If the resource
> > requested
> > + * are "normal" (and not legacy) resources, the arbiter will
> > first check
> > + * wether the card is doing legacy decoding for that type of
> > resource. If
> > + * yes, the lock is "converted" into a legacy resource lock.
> > + * The arbiter will first look for all VGA cards that might
> > conflict
> > + * and disable their IOs and/or Memory access, inlcuding VGA
> > forwarding
> > + * on P2P bridges if necessary, so that the requested
> > resources can
> > + * be used. Then, the card is marked as locking these
> > resources and
> > + * the IO and/or Memory accesse are enabled on the card
> > (including
> > + * VGA forwarding on parent P2P bridges if any).
> > + * This function will block if some conflicting card is
> > already locking
> > + * one of the required resources (or any resource on a
> > different bus
> > + * segment, since P2P bridges don't differenciate VGA memory
> > and IO
> > + * afaik). You can indicate wether this blocking should be
> > interruptible
> > + * by a signal (for userland interface) or not.
> > + * Must not be called at interrupt time or in atomic context.
> > + * If the card already owns the resources, the function
> > succeeds.
> > + * Nested calls are supported (a per-resource counter is
> > maintained)
> > + */
> > +
> > +extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
> > +
> > int interruptible); +
> > +/**
> > + * vga_get_interruptible
> > + *
> > + * Shortcut to vga_get
> > + */
> > +
> > +static inline int vga_get_interruptible(struct pci_dev *pdev,
> > +
> > unsigned int rsrc) +{
> > + return vga_get(pdev, rsrc, 1);
> > +}
> > +
> > +/**
> > + * vga_get_interruptible
> > + *
> > + * Shortcut to vga_get
> > + */
> > +
> > +static inline int vga_get_uninterruptible(struct pci_dev *pdev,
> > +
> > unsigned int rsrc) +{
> > + return vga_get(pdev, rsrc, 0);
> > +}
> > +
> > +/**
> > + * vga_tryget - try to acquire & lock legacy VGA resources
> > + *
> > + * @pdev: pci devivce of VGA card or NULL for system default
> > + * @rsrc: bit mask of resources to acquire and lock
> > + *
> > + * This function performs the same operation as vga_get(), but
> > + * will return an error (-EBUSY) instead of blocking if the
> > resources
> > + * are already locked by another card. It can be called in any
> > context
> > + */
> > +
> > +extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
> > +
> > +/**
> > + * vga_put - release lock on legacy VGA resources
> > + *
> > + * @pdev: pci device of VGA card or NULL for system default
> > + * @rsrc: but mask of resource to release
> > + *
> > + * This function releases resources previously locked by
> > vga_get()
> > + * or vga_tryget(). The resources aren't disabled right away,
> > so
> > + * that a subsequence vga_get() on the same card will succeed
> > + * immediately. Resources have a counter, so locks are only
> > + * released if the counter reaches 0.
> > + */
> > +
> > +extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
> > +
> > +
> > +/**
> > + * vga_default_device
> > + *
> > + * This can be defined by the platform. The default
> > implementation
> > + * is rather dumb and will probably only work properly on
> > single
> > + * vga card setups and/or x86 platforms.
> > + *
> > + * If your VGA default device is not PCI, you'll have to return
> > + * NULL here. In this case, I assume it will not conflict with
> > + * any PCI card. If this is not true, I'll have to define two
> > archs
> > + * hooks for enabling/disabling the VGA default device if that
> > is
> > + * possible. This may be a problem with real _ISA_ VGA cards,
> > in
> > + * addition to a PCI one. I don't know at this point how to
> > deal
> > + * with that card. Can theirs IOs be disabled at all ? If not,
> > then
> > + * I suppose it's a matter of having the proper arch hook
> > telling
> > + * us about it, so we basically never allow anybody to succeed
> > a
> > + * vga_get()...
> > + */
> > +
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > +extern struct pci_dev *vga_default_device(void);
> > +#endif
> > +
> > +/**
> > + * vga_conflicts
> > + *
> > + * Architectures should define this if they have several
> > + * independant PCI domains that can afford concurrent VGA
> > + * decoding
> > + */
> > +
> > +#ifndef __ARCH_HAS_VGA_CONFLICT
> > +static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev
> > *p2) +{
> > + return 1;
> > +}
> > +#endif
> > +
> > +/*
> > + * Register a client with the VGA arbitration logic
> > + * return value: number of VGA devices in system.
> > + *
> > + * Clients have two callback mechanisms they can use.
> > + * irq enable/disable callback -
> > + * If a client can't disable its GPUs VGA resources, then we
> > + * need to be able to ask it to turn off its irqs when we
> > + * turn off its mem and io decoding.
> > + * set_vga_decode
> > + * If a client can disable its GPU VGA resource, it will
> > + * get a callback from this to set the encode/decode state
> > + *
> > + * Clients with disable abilities should check the return value
> > + * of this function and if the VGA device count is > 1, should
> > + * disable VGA decoding resources.
> > + *
> > + * Rationale: we cannot disable VGA decode resources
> > unconditionally
> > + * some single GPU laptops seem to require ACPI or BIOS access to
> > the
> > + * VGA registers to control things like backlights etc.
> > + * Hopefully newer multi-GPU laptops do something saner, and
> > desktops
> > + * won't have any special ACPI for this.
> > + */
> > +int vga_client_register(struct pci_dev *pdev, void *cookie,
> > + void (*irq_set_state)(void *cookie, bool
> > state),
> > + unsigned int (*set_vga_decode)(void
> > *cookie, bool state)); +
> > +#endif /* LINUX_VGA_H */
> > --
> > 1.6.0.6
> Tiago
>
> ------------------------------------------------------------------------------
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>
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH] PCI/VGA: fix header commentary
2009-08-17 17:37 ` Jesse Barnes
@ 2009-09-12 15:02 ` Tiago Vignatti
2009-09-17 16:41 ` Jesse Barnes
0 siblings, 1 reply; 17+ messages in thread
From: Tiago Vignatti @ 2009-09-12 15:02 UTC (permalink / raw)
To: Jesse Barnes
Cc: dri-devel@lists.sf.net, linux-kernel@vger.kernel.org,
Tiago Vignatti
Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
---
Amend this somewhere, Jesse. Thanks.
include/linux/vgaarb.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
index e81c64a..290409c 100644
--- a/include/linux/vgaarb.h
+++ b/include/linux/vgaarb.h
@@ -1,5 +1,5 @@
/*
- * vgaarb.c
+ * vgaarb.h
*
* (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
* (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
--
1.5.6.3
^ permalink raw reply related [flat|nested] 17+ messages in thread
* Re: [PATCH] PCI/VGA: fix header commentary
2009-09-12 15:02 ` [PATCH] PCI/VGA: fix header commentary Tiago Vignatti
@ 2009-09-17 16:41 ` Jesse Barnes
0 siblings, 0 replies; 17+ messages in thread
From: Jesse Barnes @ 2009-09-17 16:41 UTC (permalink / raw)
To: Tiago Vignatti; +Cc: dri-devel@lists.sf.net, linux-kernel@vger.kernel.org
On Sat, 12 Sep 2009 18:02:31 +0300
Tiago Vignatti <tiago.vignatti@nokia.com> wrote:
> Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
> ---
>
> Amend this somewhere, Jesse. Thanks.
>
>
> include/linux/vgaarb.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
> index e81c64a..290409c 100644
> --- a/include/linux/vgaarb.h
> +++ b/include/linux/vgaarb.h
> @@ -1,5 +1,5 @@
> /*
> - * vgaarb.c
> + * vgaarb.h
> *
> * (C) Copyright 2005 Benjamin Herrenschmidt
> <benh@kernel.crashing.org>
> * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
I removed the referenced to the filename altogether and replaced it
with a short comment. Thanks.
--
Jesse Barnes, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 17+ messages in thread