[PATCH v3 -mm 7/7] I/OAT: Add DCA services

Shannon Nelson
2007-08-29T19:03:47Z

Add code to connect to the DCA driver and provide cpu tags for use by
drivers that would like to use Direct Cache Access hints.

[Adrian Bunk] Several Kconfig cleanup items
[Andrew Morten, Chris Leech] Fix for using cpu_physical_id() even when
built for uni-processor

Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Acked-by: David S. Miller <davem@davemloft.net>
---

drivers/dca/Kconfig | 6 -
drivers/dma/Kconfig | 60 +++++----
drivers/dma/Makefile | 2
drivers/dma/ioat.c | 17 ++-
drivers/dma/ioat_dca.c | 263 +++++++++++++++++++++++++++++++++++++++++
drivers/dma/ioatdma.h | 3
include/asm-i386/cpufeature.h | 1
7 files changed, 320 insertions(+), 32 deletions(-)

diff --git a/drivers/dca/Kconfig b/drivers/dca/Kconfig
index e2f7436..94f0364 100644
--- a/drivers/dca/Kconfig
+++ b/drivers/dca/Kconfig
@@ -3,9 +3,5 @@
#

config DCA
- tristate "DCA support for clients and providers"
- default m
- help
- This is a server to help modules that want to use Direct Cache
- Access to find DCA providers that will supply correct CPU tags.
+ tristate

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 8f670da..9c91b0f 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -2,42 +2,52 @@
# DMA engine configuration
#

-menu "DMA Engine support"
- depends on HAS_DMA
+menuconfig DMADEVICES
+ bool "DMA Offload Engine support"
+ depends on (PCI && X86) || ARCH_IOP32X || ARCH_IOP33X || ARCH_IOP13XX
+ help
+ Intel(R) offload engines enable offloading memory copies in the
+ network stack and RAID operations in the MD driver.
+
+if DMADEVICES
+
+comment "DMA Devices"
+
+config INTEL_IOATDMA
+ tristate "Intel I/OAT DMA support"
+ depends on PCI && X86
+ select DMA_ENGINE
+ select DCA
+ help
+ Enable support for the Intel(R) I/OAT DMA engine present
+ in recent Intel Xeon chipsets.
+
+ Say Y here if you have such a chipset.
+
+ If unsure, say N.
+
+config INTEL_IOP_ADMA
+ tristate "Intel IOP ADMA support"
+ depends on ARCH_IOP32X || ARCH_IOP33X || ARCH_IOP13XX
+ select ASYNC_CORE
+ select DMA_ENGINE
+ help
+ Enable support for the Intel(R) IOP Series RAID engines.

config DMA_ENGINE
- bool "Support for DMA engines"
- ---help---
- DMA engines offload bulk memory operations from the CPU to dedicated
- hardware, allowing the operations to happen asynchronously.
+ bool

comment "DMA Clients"
+ depends on DMA_ENGINE

config NET_DMA
bool "Network: TCP receive copy offload"
depends on DMA_ENGINE && NET
default y
- ---help---
+ help
This enables the use of DMA engines in the network stack to
offload receive copy-to-user operations, freeing CPU cycles.
Since this is the main user of the DMA engine, it should be enabled;
say Y here.

-comment "DMA Devices"
-
-config INTEL_IOATDMA
- tristate "Intel I/OAT DMA support"
- depends on DMA_ENGINE && PCI
- default m
- ---help---
- Enable support for the Intel(R) I/OAT DMA engine.
-
-config INTEL_IOP_ADMA
- tristate "Intel IOP ADMA support"
- depends on DMA_ENGINE && (ARCH_IOP32X || ARCH_IOP33X || ARCH_IOP13XX)
- select ASYNC_CORE
- default m
- ---help---
- Enable support for the Intel(R) IOP Series RAID engines.
-
-endmenu
+endif
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index cec0c9c..b152cd8 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -1,5 +1,5 @@
obj-$(CONFIG_DMA_ENGINE) += dmaengine.o
obj-$(CONFIG_NET_DMA) += iovlock.o
obj-$(CONFIG_INTEL_IOATDMA) += ioatdma.o
-ioatdma-objs := ioat.o ioat_dma.o
+ioatdma-objs := ioat.o ioat_dma.o ioat_dca.o
obj-$(CONFIG_INTEL_IOP_ADMA) += iop-adma.o
diff --git a/drivers/dma/ioat.c b/drivers/dma/ioat.c
index ae5817b..f7276bf 100644
--- a/drivers/dma/ioat.c
+++ b/drivers/dma/ioat.c
@@ -1,6 +1,6 @@
/*
* Intel I/OAT DMA Linux driver
- * Copyright(c) 2004 - 2007 Intel Corporation.
+ * Copyright(c) 2007 Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
@@ -29,6 +29,7 @@
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
+#include <linux/dca.h>
#include "ioatdma.h"
#include "ioatdma_registers.h"
#include "ioatdma_hw.h"
@@ -49,6 +50,7 @@ struct ioat_device {
struct pci_dev *pdev;
void __iomem *iobase;
struct ioatdma_device *dma;
+ struct dca_provider *dca;
};

static int __devinit ioat_probe(struct pci_dev *pdev,
@@ -57,6 +59,10 @@ static int __devinit ioat_probe(struct pci_dev *pdev,
static void __devexit ioat_remove(struct pci_dev *pdev);
#endif

+static int ioat_dca_enabled = 1;
+module_param(ioat_dca_enabled, int, 0644);
+MODULE_PARM_DESC(ioat_dca_enabled, "control support of dca service (default: 1)");
+
static int ioat_setup_functionality(struct pci_dev *pdev, void __iomem *iobase)
{
struct ioat_device *device = pci_get_drvdata(pdev);
@@ -67,6 +73,8 @@ static int ioat_setup_functionality(struct pci_dev *pdev, void __iomem *iobase)
switch (version) {
case IOAT_VER_1_2:
device->dma = ioat_dma_probe(pdev, iobase);
+ if (ioat_dca_enabled)
+ device->dca = ioat_dca_init(pdev, iobase);
break;
default:
err = -ENODEV;
@@ -83,6 +91,13 @@ static void ioat_shutdown_functionality(struct pci_dev *pdev)
ioat_dma_remove(device->dma);
device->dma = NULL;
}
+
+ if (device->dca) {
+ unregister_dca_provider(device->dca);
+ free_dca_provider(device->dca);
+ device->dca = NULL;
+ }
+
}

static struct pci_driver ioat_pci_drv = {
diff --git a/drivers/dma/ioat_dca.c b/drivers/dma/ioat_dca.c
new file mode 100644
index 0000000..2ae04c3
--- /dev/null
+++ b/drivers/dma/ioat_dca.c
@@ -0,0 +1,263 @@
+/*
+ * Intel I/OAT DMA Linux driver
+ * Copyright(c) 2007 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/dca.h>
+
+/* either a kernel change is needed, or we need something like this in kernel */
+#ifndef CONFIG_SMP
+#include <asm/smp.h>
+#undef cpu_physical_id
+#define cpu_physical_id(cpu) (cpuid_ebx(1) >> 24)
+#endif
+
+#include "ioatdma.h"
+#include "ioatdma_registers.h"
+
+/*
+ * Bit 16 of a tag map entry is the "valid" bit, if it is set then bits 0:15
+ * contain the bit number of the APIC ID to map into the DCA tag. If the valid
+ * bit is not set, then the value must be 0 or 1 and defines the bit in the tag.
+ */
+#define DCA_TAG_MAP_VALID 0x80
+
+/*
+ * "Legacy" DCA systems do not implement the DCA register set in the
+ * I/OAT device. Software needs direct support for their tag mappings.
+ */
+
+#define APICID_BIT(x) (DCA_TAG_MAP_VALID | (x))
+#define IOAT_TAG_MAP_LEN 8
+
+static u8 ioat_tag_map_BNB[IOAT_TAG_MAP_LEN] = {
+ 1, APICID_BIT(1), APICID_BIT(2), APICID_BIT(2), };
+static u8 ioat_tag_map_SCNB[IOAT_TAG_MAP_LEN] = {
+ 1, APICID_BIT(1), APICID_BIT(2), APICID_BIT(2), };
+static u8 ioat_tag_map_CNB[IOAT_TAG_MAP_LEN] = {
+ 1, APICID_BIT(1), APICID_BIT(3), APICID_BIT(4), APICID_BIT(2), };
+static u8 ioat_tag_map_UNISYS[IOAT_TAG_MAP_LEN] = { 0 };
+
+/* pack PCI B/D/F into a u16 */
+static inline u16 dcaid_from_pcidev(struct pci_dev *pci)
+{
+ return (pci->bus->number << 8) | pci->devfn;
+}
+
+static int dca_enabled_in_bios(void)
+{
+ /* CPUID level 9 returns DCA configuration */
+ /* Bit 0 indicates DCA enabled by the BIOS */
+ unsigned long cpuid_level_9;
+ int res;
+
+ cpuid_level_9 = cpuid_eax(9);
+ res = test_bit(0, &cpuid_level_9);
+ if (!res)
+ printk(KERN_ERR "ioat dma: DCA is disabled in BIOS\n");
+
+ return res;
+}
+
+static int system_has_dca_enabled(void)
+{
+ if (boot_cpu_has(X86_FEATURE_DCA))
+ return dca_enabled_in_bios();
+
+ printk(KERN_ERR "ioat dma: boot cpu doesn't have X86_FEATURE_DCA\n");
+ return 0;
+}
+
+struct ioat_dca_slot {
+ struct pci_dev *pdev; /* requester device */
+ u16 rid; /* requester id, as used by IOAT */
+};
+
+#define IOAT_DCA_MAX_REQ 6
+
+struct ioat_dca_priv {
+ void __iomem *iobase;
+ void *dca_base;
+ int max_requesters;
+ int requester_count;
+ u8 tag_map[IOAT_TAG_MAP_LEN];
+ struct ioat_dca_slot req_slots[0];
+};
+
+/* 5000 series chipset DCA Port Requester ID Table Entry Format
+ * [15:8] PCI-Express Bus Number
+ * [7:3] PCI-Express Device Number
+ * [2:0] PCI-Express Function Number
+ *
+ * 5000 series chipset DCA control register format
+ * [7:1] Reserved (0)
+ * [0] Ignore Function Number
+ */
+
+static int ioat_dca_add_requester(struct dca_provider *dca, struct device *dev)
+{
+ struct ioat_dca_priv *ioatdca = dca_priv(dca);
+ struct pci_dev *pdev;
+ int i;
+ u16 id;
+
+ /* This implementation only supports PCI-Express */
+ if (dev->bus != &pci_bus_type)
+ return -ENODEV;
+ pdev = to_pci_dev(dev);
+ id = dcaid_from_pcidev(pdev);
+
+ if (ioatdca->requester_count == ioatdca->max_requesters)
+ return -ENODEV;
+
+ for (i = 0; i < ioatdca->max_requesters; i++) {
+ if (ioatdca->req_slots[i].pdev == NULL) {
+ /* found an empty slot */
+ ioatdca->requester_count++;
+ ioatdca->req_slots[i].pdev = pdev;
+ ioatdca->req_slots[i].rid = id;
+ writew(id, ioatdca->dca_base + (i * 4));
+ /* make sure the ignore function bit is off */
+ writeb(0, ioatdca->dca_base + (i * 4) + 2);
+ return i;
+ }
+ }
+ /* Error, ioatdma->requester_count is out of whack */
+ return -EFAULT;
+}
+
+static int ioat_dca_remove_requester(struct dca_provider *dca,
+ struct device *dev)
+{
+ struct ioat_dca_priv *ioatdca = dca_priv(dca);
+ struct pci_dev *pdev;
+ int i;
+
+ /* This implementation only supports PCI-Express */
+ if (dev->bus != &pci_bus_type)
+ return -ENODEV;
+ pdev = to_pci_dev(dev);
+
+ for (i = 0; i < ioatdca->max_requesters; i++) {
+ if (ioatdca->req_slots[i].pdev == pdev) {
+ writew(0, ioatdca->dca_base + (i * 4));
+ ioatdca->req_slots[i].pdev = NULL;
+ ioatdca->req_slots[i].rid = 0;
+ ioatdca->requester_count--;
+ return i;
+ }
+ }
+ return -ENODEV;
+}
+
+static u8 ioat_dca_get_tag(struct dca_provider *dca, int cpu)
+{
+ struct ioat_dca_priv *ioatdca = dca_priv(dca);
+ int i, apic_id, bit, value;
+ u8 entry, tag;
+
+ tag = 0;
+ apic_id = cpu_physical_id(cpu);
+
+ for (i = 0; i < IOAT_TAG_MAP_LEN; i++) {
+ entry = ioatdca->tag_map[i];
+ if (entry & DCA_TAG_MAP_VALID) {
+ bit = entry & ~DCA_TAG_MAP_VALID;
+ value = (apic_id & (1 << bit)) ? 1 : 0;
+ } else {
+ value = entry ? 1 : 0;
+ }
+ tag |= (value << i);
+ }
+ return tag;
+}
+
+static struct dca_ops ioat_dca_ops = {
+ .add_requester = ioat_dca_add_requester,
+ .remove_requester = ioat_dca_remove_requester,
+ .get_tag = ioat_dca_get_tag,
+};
+
+
+struct dca_provider *ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
+{
+ struct dca_provider *dca;
+ struct ioat_dca_priv *ioatdca;
+ u8 *tag_map = NULL;
+ int i;
+ int err;
+
+ if (!system_has_dca_enabled())
+ return NULL;
+
+ /* I/OAT v1 systems must have a known tag_map to support DCA */
+ switch (pdev->vendor) {
+ case PCI_VENDOR_ID_INTEL:
+ switch (pdev->device) {
+ case PCI_DEVICE_ID_INTEL_IOAT:
+ tag_map = ioat_tag_map_BNB;
+ break;
+ case PCI_DEVICE_ID_INTEL_IOAT_CNB:
+ tag_map = ioat_tag_map_CNB;
+ break;
+ case PCI_DEVICE_ID_INTEL_IOAT_SCNB:
+ tag_map = ioat_tag_map_SCNB;
+ break;
+ }
+ break;
+ case PCI_VENDOR_ID_UNISYS:
+ switch (pdev->device) {
+ case PCI_DEVICE_ID_UNISYS_DMA_DIRECTOR:
+ tag_map = ioat_tag_map_UNISYS;
+ break;
+ }
+ break;
+ }
+ if (tag_map == NULL)
+ return NULL;
+
+ dca = alloc_dca_provider(&ioat_dca_ops,
+ sizeof(*ioatdca) +
+ (sizeof(struct ioat_dca_slot) * IOAT_DCA_MAX_REQ));
+ if (!dca)
+ return NULL;
+
+ ioatdca = dca_priv(dca);
+ ioatdca->max_requesters = IOAT_DCA_MAX_REQ;
+
+ ioatdca->dca_base = iobase + 0x54;
+
+ /* copy over the APIC ID to DCA tag mapping */
+ for (i = 0; i < IOAT_TAG_MAP_LEN; i++)
+ ioatdca->tag_map[i] = tag_map[i];
+
+ err = register_dca_provider(dca, &pdev->dev);
+ if (err) {
+ free_dca_provider(dca);
+ return NULL;
+ }
+
+ return dca;
+}
+
diff --git a/drivers/dma/ioatdma.h b/drivers/dma/ioatdma.h
index 2abf0b8..2a319e1 100644
--- a/drivers/dma/ioatdma.h
+++ b/drivers/dma/ioatdma.h
@@ -132,9 +132,12 @@ struct ioat_desc_sw {
struct ioatdma_device *ioat_dma_probe(struct pci_dev *pdev,
void __iomem *iobase);
void ioat_dma_remove(struct ioatdma_device *device);
+struct dca_provider *ioat_dca_init(struct pci_dev *pdev,
+ void __iomem *iobase);
#else
#define ioat_dma_probe(pdev, iobase) NULL
#define ioat_dma_remove(device) do { } while (0)
+#define ioat_dca_init(pdev, iobase) NULL
#endif

#endif /* IOATDMA_H */
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index 7b3aa28..f17e688 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -92,6 +92,7 @@
#define X86_FEATURE_CID (4*32+10) /* Context ID */
#define X86_FEATURE_CX16 (4*32+13) /* CMPXCHG16B */
#define X86_FEATURE_XTPR (4*32+14) /* Send Task Priority Messages */
+#define X86_FEATURE_DCA (4*32+18) /* Direct Cache Access */

/* VIA/Cyrix/Centaur-defined CPU features, CPUID level 0xC0000001, word 5 */
#define X86_FEATURE_XSTORE (5*32+ 2) /* on-CPU RNG present (xstore insn) */