[PATCH 7/7] I/OAT: Add DCA services

[Shannon Nelson <shannon.nelson@intel.com>]

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.

Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
---

 drivers/dma/Makefile   |    2 
 drivers/dma/ioat.c     |   12 ++
 drivers/dma/ioat_dca.c |  259 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/dma/ioatdma.h  |    2 
 4 files changed, 273 insertions(+), 2 deletions(-)

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 9d9f672..8ae8c53 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,
@@ -65,6 +67,7 @@ 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);
+		device->dca = ioat_dca_init(pdev, iobase);
 		break;
 	default:
 		err = -ENODEV;
@@ -81,6 +84,13 @@ 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..c3a500b
--- /dev/null
+++ b/drivers/dma/ioat_dca.c
@@ -0,0 +1,259 @@
+/*
+ * 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>
+#include "ioatdma.h"
+#include "ioatdma_registers.h"
+
+/* THIS STUFF NEEDS TO LIVE SOMEWHERE ELSE */
+#define X86_FEATURE_DCA	(4*32+18) /* Direct Cache Access */
+/* / THIS STUFF NEEDS TO LIVE SOMEWHERE ELSE */
+
+/*
+ * 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 2b499d5..bab2a72 100644
--- a/drivers/dma/ioatdma.h
+++ b/drivers/dma/ioatdma.h
@@ -133,9 +133,11 @@ struct ioat_desc_sw {
 #if defined(CONFIG_INTEL_IOATDMA) || defined(CONFIG_INTEL_IOATDMA_MODULE)
 struct ioatdma_device *ioat_dma_probe(struct pci_dev *, void __iomem *);
 void ioat_dma_remove(struct ioatdma_device *device);
+struct dca_provider *ioat_dca_init(struct pci_dev *, void __iomem *);
 #else
 #define ioat_dma_probe(pdev, io)                NULL
 #define ioat_dma_remove(dev)            do { } while (0)
+#define ioat_dca_init(pdev, io)			NULL
 #endif
 
 #endif /* IOATDMA_H */