[PATCH] fb: add support for handoff from firmware to hw framebuffers

[Dave Airlie <airlied@gmail.com>]

From: Dave Airlie <airlied@redhat.com>

With KMS we have ran into an issue where we really want the KMS fb driver
to be the one running the console, so panics etc can be shown by switching
out of X etc.

However with vesafb/efifb built-in, we end up with those on fb0 and the
KMS fb driver on fb1, driving the same piece of hw, so this adds an fb info
flag to denote a firmware fbdev, and adds a new aperture base/size range
which can be compared when the hw drivers are installed to see if there
is a conflict with a firmware driver, and if there is the firmware driver is
unregistered and the hw driver takes over.

It uses new aperture_base/size members instead of comparing on the fix
smem_start/length, as smem_start/length might for example only cover the
first 1MB of the PCI aperture, and we could allocate the kms fb from 8MB
into the aperture, thus they would never overlap.

Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/i915/intel_fb.c |    8 ++++++++
 drivers/video/efifb.c           |    5 ++++-
 drivers/video/fbmem.c           |   24 ++++++++++++++++++++++++
 drivers/video/vesafb.c          |    6 +++++-
 include/linux/fb.h              |    9 ++++++++-
 5 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_fb.c b/drivers/gpu/drm/i915/intel_fb.c
index e4652dc..f1849d3 100644
--- a/drivers/gpu/drm/i915/intel_fb.c
+++ b/drivers/gpu/drm/i915/intel_fb.c
@@ -504,6 +504,14 @@ static int intelfb_create(struct drm_device *dev, uint32_t fb_width,
 	info->fbops = &intelfb_ops;
 
 	info->fix.line_length = fb->pitch;
+
+	/* setup aperture base/size for vesafb takeover */
+	info->aperture_base = dev->mode_config.fb_base;
+	if (IS_I9XX(dev))
+		info->aperture_size = pci_resource_len(dev->pdev, 2);
+	else
+		info->aperture_size = pci_resource_len(dev->pdev, 0);
+
 	info->fix.smem_start = dev->mode_config.fb_base + obj_priv->gtt_offset;
 	info->fix.smem_len = size;
 
diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c
index 8dea2bc..eb12182 100644
--- a/drivers/video/efifb.c
+++ b/drivers/video/efifb.c
@@ -280,6 +280,9 @@ static int __init efifb_probe(struct platform_device *dev)
 	info->pseudo_palette = info->par;
 	info->par = NULL;
 
+	info->aperture_base = efifb_fix.smem_start;
+	info->aperture_size = size_total;
+
 	info->screen_base = ioremap(efifb_fix.smem_start, efifb_fix.smem_len);
 	if (!info->screen_base) {
 		printk(KERN_ERR "efifb: abort, cannot ioremap video memory "
@@ -337,7 +340,7 @@ static int __init efifb_probe(struct platform_device *dev)
 	info->fbops = &efifb_ops;
 	info->var = efifb_defined;
 	info->fix = efifb_fix;
-	info->flags = FBINFO_FLAG_DEFAULT;
+	info->flags = FBINFO_FLAG_DEFAULT | FBINFO_MISC_FIRMWARE;
 
 	if ((err = fb_alloc_cmap(&info->cmap, 256, 0)) < 0) {
 		printk(KERN_ERR "efifb: cannot allocate colormap\n");
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index d412a1d..3dd033b 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1462,6 +1462,16 @@ static int fb_check_foreignness(struct fb_info *fi)
 	return 0;
 }
 
+static bool fb_compare_aperture_sizes(struct fb_info *gen, struct fb_info *hw)
+{
+	/* is the generic aperture base the same as the HW one */
+	if (gen->aperture_base == hw->aperture_base)
+		return true;
+	/* is the generic aperture base inside the hw base->hw base+size */
+	if (gen->aperture_base > hw->aperture_base && gen->aperture_base <= hw->aperture_base + hw->aperture_size)
+		return true;
+	return false;
+}
 /**
  *	register_framebuffer - registers a frame buffer device
  *	@fb_info: frame buffer info structure
@@ -1485,6 +1495,20 @@ register_framebuffer(struct fb_info *fb_info)
 	if (fb_check_foreignness(fb_info))
 		return -ENOSYS;
 
+	/* check all firmware fbs and kick off if the base addr overlaps */
+	for (i = 0 ; i < FB_MAX; i++) {
+		if (!registered_fb[i])
+			continue;
+
+		if (registered_fb[i]->flags & FBINFO_MISC_FIRMWARE) {
+			if (fb_compare_aperture_sizes(registered_fb[i], fb_info)) {
+				printk("fb: conflicting fb hw usage - removing generic driver\n", registered_fb[i]->aperture_base, fb_info->aperture_base);
+				unregister_framebuffer(registered_fb[i]);
+				break;
+			}
+		}
+	}
+
 	num_registered_fb++;
 	for (i = 0 ; i < FB_MAX; i++)
 		if (!registered_fb[i])
diff --git a/drivers/video/vesafb.c b/drivers/video/vesafb.c
index d6856f4..52f03b2 100644
--- a/drivers/video/vesafb.c
+++ b/drivers/video/vesafb.c
@@ -286,6 +286,10 @@ static int __init vesafb_probe(struct platform_device *dev)
 	info->pseudo_palette = info->par;
 	info->par = NULL;
 
+	/* set vesafb aperture size for generic probing */
+	info->aperture_base = screen_info.lfb_base;
+	info->aperture_size = size_total;
+
 	info->screen_base = ioremap(vesafb_fix.smem_start, vesafb_fix.smem_len);
 	if (!info->screen_base) {
 		printk(KERN_ERR
@@ -437,7 +441,7 @@ static int __init vesafb_probe(struct platform_device *dev)
 	info->fbops = &vesafb_ops;
 	info->var = vesafb_defined;
 	info->fix = vesafb_fix;
-	info->flags = FBINFO_FLAG_DEFAULT |
+	info->flags = FBINFO_FLAG_DEFAULT | FBINFO_MISC_FIRMWARE |
 		(ypan ? FBINFO_HWACCEL_YPAN : 0);
 
 	if (!ypan)
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 330c4b1..88cbe56 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -786,6 +786,8 @@ struct fb_tile_ops {
 #define FBINFO_MISC_USEREVENT          0x10000 /* event request
 						  from userspace */
 #define FBINFO_MISC_TILEBLITTING       0x20000 /* use tile blitting */
+#define FBINFO_MISC_FIRMWARE           0x40000 /* a replaceable firmware 
+						  inited framebuffer */
 
 /* A driver may set this flag to indicate that it does want a set_par to be
  * called every time when fbcon_switch is executed. The advantage is that with
@@ -854,7 +856,12 @@ struct fb_info {
 	u32 state;			/* Hardware state i.e suspend */
 	void *fbcon_par;                /* fbcon use-only private area */
 	/* From here on everything is device dependent */
-	void *par;	
+	void *par;
+	/* we need the PCI or similiar aperture base/size not
+	   smem_start/size as smem_start may just be an object
+	   allocated inside the aperture so may not actually overlap */
+	resource_size_t aperture_base;
+	resource_size_t aperture_size;
 };
 
 #ifdef MODULE
-- 
1.5.4.1


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