irqchip: GICv3: ITS command queue
authorMarc Zyngier <marc.zyngier@arm.com>
Mon, 24 Nov 2014 14:35:11 +0000 (14:35 +0000)
committerJason Cooper <jason@lakedaemon.net>
Wed, 26 Nov 2014 15:55:12 +0000 (15:55 +0000)
The ITS is configured through a number commands that the driver
issues to the HW using a memory-based circular buffer.

This patch implements the subset of commands that are required
for Linux.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-5-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
drivers/irqchip/irq-gic-v3-its.c [new file with mode: 0644]
include/linux/irqchip/arm-gic-v3.h

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
new file mode 100644 (file)
index 0000000..a5ab12c
--- /dev/null
@@ -0,0 +1,511 @@
+/*
+ * Copyright (C) 2013, 2014 ARM Limited, All Rights Reserved.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/bitmap.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/log2.h>
+#include <linux/mm.h>
+#include <linux/msi.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_pci.h>
+#include <linux/of_platform.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+
+#include <linux/irqchip/arm-gic-v3.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cputype.h>
+#include <asm/exception.h>
+
+#include "irqchip.h"
+
+#define ITS_FLAGS_CMDQ_NEEDS_FLUSHING          (1 << 0)
+
+/*
+ * Collection structure - just an ID, and a redistributor address to
+ * ping. We use one per CPU as a bag of interrupts assigned to this
+ * CPU.
+ */
+struct its_collection {
+       u64                     target_address;
+       u16                     col_id;
+};
+
+/*
+ * The ITS structure - contains most of the infrastructure, with the
+ * msi_controller, the command queue, the collections, and the list of
+ * devices writing to it.
+ */
+struct its_node {
+       raw_spinlock_t          lock;
+       struct list_head        entry;
+       struct msi_controller   msi_chip;
+       struct irq_domain       *domain;
+       void __iomem            *base;
+       unsigned long           phys_base;
+       struct its_cmd_block    *cmd_base;
+       struct its_cmd_block    *cmd_write;
+       void                    *tables[GITS_BASER_NR_REGS];
+       struct its_collection   *collections;
+       struct list_head        its_device_list;
+       u64                     flags;
+       u32                     ite_size;
+};
+
+#define ITS_ITT_ALIGN          SZ_256
+
+/*
+ * The ITS view of a device - belongs to an ITS, a collection, owns an
+ * interrupt translation table, and a list of interrupts.
+ */
+struct its_device {
+       struct list_head        entry;
+       struct its_node         *its;
+       struct its_collection   *collection;
+       void                    *itt;
+       unsigned long           *lpi_map;
+       irq_hw_number_t         lpi_base;
+       int                     nr_lpis;
+       u32                     nr_ites;
+       u32                     device_id;
+};
+
+/*
+ * ITS command descriptors - parameters to be encoded in a command
+ * block.
+ */
+struct its_cmd_desc {
+       union {
+               struct {
+                       struct its_device *dev;
+                       u32 event_id;
+               } its_inv_cmd;
+
+               struct {
+                       struct its_device *dev;
+                       u32 event_id;
+               } its_int_cmd;
+
+               struct {
+                       struct its_device *dev;
+                       int valid;
+               } its_mapd_cmd;
+
+               struct {
+                       struct its_collection *col;
+                       int valid;
+               } its_mapc_cmd;
+
+               struct {
+                       struct its_device *dev;
+                       u32 phys_id;
+                       u32 event_id;
+               } its_mapvi_cmd;
+
+               struct {
+                       struct its_device *dev;
+                       struct its_collection *col;
+                       u32 id;
+               } its_movi_cmd;
+
+               struct {
+                       struct its_device *dev;
+                       u32 event_id;
+               } its_discard_cmd;
+
+               struct {
+                       struct its_collection *col;
+               } its_invall_cmd;
+       };
+};
+
+/*
+ * The ITS command block, which is what the ITS actually parses.
+ */
+struct its_cmd_block {
+       u64     raw_cmd[4];
+};
+
+#define ITS_CMD_QUEUE_SZ               SZ_64K
+#define ITS_CMD_QUEUE_NR_ENTRIES       (ITS_CMD_QUEUE_SZ / sizeof(struct its_cmd_block))
+
+typedef struct its_collection *(*its_cmd_builder_t)(struct its_cmd_block *,
+                                                   struct its_cmd_desc *);
+
+static void its_encode_cmd(struct its_cmd_block *cmd, u8 cmd_nr)
+{
+       cmd->raw_cmd[0] &= ~0xffUL;
+       cmd->raw_cmd[0] |= cmd_nr;
+}
+
+static void its_encode_devid(struct its_cmd_block *cmd, u32 devid)
+{
+       cmd->raw_cmd[0] &= ~(0xffffUL << 32);
+       cmd->raw_cmd[0] |= ((u64)devid) << 32;
+}
+
+static void its_encode_event_id(struct its_cmd_block *cmd, u32 id)
+{
+       cmd->raw_cmd[1] &= ~0xffffffffUL;
+       cmd->raw_cmd[1] |= id;
+}
+
+static void its_encode_phys_id(struct its_cmd_block *cmd, u32 phys_id)
+{
+       cmd->raw_cmd[1] &= 0xffffffffUL;
+       cmd->raw_cmd[1] |= ((u64)phys_id) << 32;
+}
+
+static void its_encode_size(struct its_cmd_block *cmd, u8 size)
+{
+       cmd->raw_cmd[1] &= ~0x1fUL;
+       cmd->raw_cmd[1] |= size & 0x1f;
+}
+
+static void its_encode_itt(struct its_cmd_block *cmd, u64 itt_addr)
+{
+       cmd->raw_cmd[2] &= ~0xffffffffffffUL;
+       cmd->raw_cmd[2] |= itt_addr & 0xffffffffff00UL;
+}
+
+static void its_encode_valid(struct its_cmd_block *cmd, int valid)
+{
+       cmd->raw_cmd[2] &= ~(1UL << 63);
+       cmd->raw_cmd[2] |= ((u64)!!valid) << 63;
+}
+
+static void its_encode_target(struct its_cmd_block *cmd, u64 target_addr)
+{
+       cmd->raw_cmd[2] &= ~(0xffffffffUL << 16);
+       cmd->raw_cmd[2] |= (target_addr & (0xffffffffUL << 16));
+}
+
+static void its_encode_collection(struct its_cmd_block *cmd, u16 col)
+{
+       cmd->raw_cmd[2] &= ~0xffffUL;
+       cmd->raw_cmd[2] |= col;
+}
+
+static inline void its_fixup_cmd(struct its_cmd_block *cmd)
+{
+       /* Let's fixup BE commands */
+       cmd->raw_cmd[0] = cpu_to_le64(cmd->raw_cmd[0]);
+       cmd->raw_cmd[1] = cpu_to_le64(cmd->raw_cmd[1]);
+       cmd->raw_cmd[2] = cpu_to_le64(cmd->raw_cmd[2]);
+       cmd->raw_cmd[3] = cpu_to_le64(cmd->raw_cmd[3]);
+}
+
+static struct its_collection *its_build_mapd_cmd(struct its_cmd_block *cmd,
+                                                struct its_cmd_desc *desc)
+{
+       unsigned long itt_addr;
+       u8 size = order_base_2(desc->its_mapd_cmd.dev->nr_ites);
+
+       itt_addr = virt_to_phys(desc->its_mapd_cmd.dev->itt);
+       itt_addr = ALIGN(itt_addr, ITS_ITT_ALIGN);
+
+       its_encode_cmd(cmd, GITS_CMD_MAPD);
+       its_encode_devid(cmd, desc->its_mapd_cmd.dev->device_id);
+       its_encode_size(cmd, size - 1);
+       its_encode_itt(cmd, itt_addr);
+       its_encode_valid(cmd, desc->its_mapd_cmd.valid);
+
+       its_fixup_cmd(cmd);
+
+       return desc->its_mapd_cmd.dev->collection;
+}
+
+static struct its_collection *its_build_mapc_cmd(struct its_cmd_block *cmd,
+                                                struct its_cmd_desc *desc)
+{
+       its_encode_cmd(cmd, GITS_CMD_MAPC);
+       its_encode_collection(cmd, desc->its_mapc_cmd.col->col_id);
+       its_encode_target(cmd, desc->its_mapc_cmd.col->target_address);
+       its_encode_valid(cmd, desc->its_mapc_cmd.valid);
+
+       its_fixup_cmd(cmd);
+
+       return desc->its_mapc_cmd.col;
+}
+
+static struct its_collection *its_build_mapvi_cmd(struct its_cmd_block *cmd,
+                                                 struct its_cmd_desc *desc)
+{
+       its_encode_cmd(cmd, GITS_CMD_MAPVI);
+       its_encode_devid(cmd, desc->its_mapvi_cmd.dev->device_id);
+       its_encode_event_id(cmd, desc->its_mapvi_cmd.event_id);
+       its_encode_phys_id(cmd, desc->its_mapvi_cmd.phys_id);
+       its_encode_collection(cmd, desc->its_mapvi_cmd.dev->collection->col_id);
+
+       its_fixup_cmd(cmd);
+
+       return desc->its_mapvi_cmd.dev->collection;
+}
+
+static struct its_collection *its_build_movi_cmd(struct its_cmd_block *cmd,
+                                                struct its_cmd_desc *desc)
+{
+       its_encode_cmd(cmd, GITS_CMD_MOVI);
+       its_encode_devid(cmd, desc->its_movi_cmd.dev->device_id);
+       its_encode_event_id(cmd, desc->its_movi_cmd.id);
+       its_encode_collection(cmd, desc->its_movi_cmd.col->col_id);
+
+       its_fixup_cmd(cmd);
+
+       return desc->its_movi_cmd.dev->collection;
+}
+
+static struct its_collection *its_build_discard_cmd(struct its_cmd_block *cmd,
+                                                   struct its_cmd_desc *desc)
+{
+       its_encode_cmd(cmd, GITS_CMD_DISCARD);
+       its_encode_devid(cmd, desc->its_discard_cmd.dev->device_id);
+       its_encode_event_id(cmd, desc->its_discard_cmd.event_id);
+
+       its_fixup_cmd(cmd);
+
+       return desc->its_discard_cmd.dev->collection;
+}
+
+static struct its_collection *its_build_inv_cmd(struct its_cmd_block *cmd,
+                                               struct its_cmd_desc *desc)
+{
+       its_encode_cmd(cmd, GITS_CMD_INV);
+       its_encode_devid(cmd, desc->its_inv_cmd.dev->device_id);
+       its_encode_event_id(cmd, desc->its_inv_cmd.event_id);
+
+       its_fixup_cmd(cmd);
+
+       return desc->its_inv_cmd.dev->collection;
+}
+
+static struct its_collection *its_build_invall_cmd(struct its_cmd_block *cmd,
+                                                  struct its_cmd_desc *desc)
+{
+       its_encode_cmd(cmd, GITS_CMD_INVALL);
+       its_encode_collection(cmd, desc->its_mapc_cmd.col->col_id);
+
+       its_fixup_cmd(cmd);
+
+       return NULL;
+}
+
+static u64 its_cmd_ptr_to_offset(struct its_node *its,
+                                struct its_cmd_block *ptr)
+{
+       return (ptr - its->cmd_base) * sizeof(*ptr);
+}
+
+static int its_queue_full(struct its_node *its)
+{
+       int widx;
+       int ridx;
+
+       widx = its->cmd_write - its->cmd_base;
+       ridx = readl_relaxed(its->base + GITS_CREADR) / sizeof(struct its_cmd_block);
+
+       /* This is incredibly unlikely to happen, unless the ITS locks up. */
+       if (((widx + 1) % ITS_CMD_QUEUE_NR_ENTRIES) == ridx)
+               return 1;
+
+       return 0;
+}
+
+static struct its_cmd_block *its_allocate_entry(struct its_node *its)
+{
+       struct its_cmd_block *cmd;
+       u32 count = 1000000;    /* 1s! */
+
+       while (its_queue_full(its)) {
+               count--;
+               if (!count) {
+                       pr_err_ratelimited("ITS queue not draining\n");
+                       return NULL;
+               }
+               cpu_relax();
+               udelay(1);
+       }
+
+       cmd = its->cmd_write++;
+
+       /* Handle queue wrapping */
+       if (its->cmd_write == (its->cmd_base + ITS_CMD_QUEUE_NR_ENTRIES))
+               its->cmd_write = its->cmd_base;
+
+       return cmd;
+}
+
+static struct its_cmd_block *its_post_commands(struct its_node *its)
+{
+       u64 wr = its_cmd_ptr_to_offset(its, its->cmd_write);
+
+       writel_relaxed(wr, its->base + GITS_CWRITER);
+
+       return its->cmd_write;
+}
+
+static void its_flush_cmd(struct its_node *its, struct its_cmd_block *cmd)
+{
+       /*
+        * Make sure the commands written to memory are observable by
+        * the ITS.
+        */
+       if (its->flags & ITS_FLAGS_CMDQ_NEEDS_FLUSHING)
+               __flush_dcache_area(cmd, sizeof(*cmd));
+       else
+               dsb(ishst);
+}
+
+static void its_wait_for_range_completion(struct its_node *its,
+                                         struct its_cmd_block *from,
+                                         struct its_cmd_block *to)
+{
+       u64 rd_idx, from_idx, to_idx;
+       u32 count = 1000000;    /* 1s! */
+
+       from_idx = its_cmd_ptr_to_offset(its, from);
+       to_idx = its_cmd_ptr_to_offset(its, to);
+
+       while (1) {
+               rd_idx = readl_relaxed(its->base + GITS_CREADR);
+               if (rd_idx >= to_idx || rd_idx < from_idx)
+                       break;
+
+               count--;
+               if (!count) {
+                       pr_err_ratelimited("ITS queue timeout\n");
+                       return;
+               }
+               cpu_relax();
+               udelay(1);
+       }
+}
+
+static void its_send_single_command(struct its_node *its,
+                                   its_cmd_builder_t builder,
+                                   struct its_cmd_desc *desc)
+{
+       struct its_cmd_block *cmd, *sync_cmd, *next_cmd;
+       struct its_collection *sync_col;
+
+       raw_spin_lock(&its->lock);
+
+       cmd = its_allocate_entry(its);
+       if (!cmd) {             /* We're soooooo screewed... */
+               pr_err_ratelimited("ITS can't allocate, dropping command\n");
+               raw_spin_unlock(&its->lock);
+               return;
+       }
+       sync_col = builder(cmd, desc);
+       its_flush_cmd(its, cmd);
+
+       if (sync_col) {
+               sync_cmd = its_allocate_entry(its);
+               if (!sync_cmd) {
+                       pr_err_ratelimited("ITS can't SYNC, skipping\n");
+                       goto post;
+               }
+               its_encode_cmd(sync_cmd, GITS_CMD_SYNC);
+               its_encode_target(sync_cmd, sync_col->target_address);
+               its_fixup_cmd(sync_cmd);
+               its_flush_cmd(its, sync_cmd);
+       }
+
+post:
+       next_cmd = its_post_commands(its);
+       raw_spin_unlock(&its->lock);
+
+       its_wait_for_range_completion(its, cmd, next_cmd);
+}
+
+static void its_send_inv(struct its_device *dev, u32 event_id)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_inv_cmd.dev = dev;
+       desc.its_inv_cmd.event_id = event_id;
+
+       its_send_single_command(dev->its, its_build_inv_cmd, &desc);
+}
+
+static void its_send_mapd(struct its_device *dev, int valid)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_mapd_cmd.dev = dev;
+       desc.its_mapd_cmd.valid = !!valid;
+
+       its_send_single_command(dev->its, its_build_mapd_cmd, &desc);
+}
+
+static void its_send_mapc(struct its_node *its, struct its_collection *col,
+                         int valid)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_mapc_cmd.col = col;
+       desc.its_mapc_cmd.valid = !!valid;
+
+       its_send_single_command(its, its_build_mapc_cmd, &desc);
+}
+
+static void its_send_mapvi(struct its_device *dev, u32 irq_id, u32 id)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_mapvi_cmd.dev = dev;
+       desc.its_mapvi_cmd.phys_id = irq_id;
+       desc.its_mapvi_cmd.event_id = id;
+
+       its_send_single_command(dev->its, its_build_mapvi_cmd, &desc);
+}
+
+static void its_send_movi(struct its_device *dev,
+                         struct its_collection *col, u32 id)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_movi_cmd.dev = dev;
+       desc.its_movi_cmd.col = col;
+       desc.its_movi_cmd.id = id;
+
+       its_send_single_command(dev->its, its_build_movi_cmd, &desc);
+}
+
+static void its_send_discard(struct its_device *dev, u32 id)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_discard_cmd.dev = dev;
+       desc.its_discard_cmd.event_id = id;
+
+       its_send_single_command(dev->its, its_build_discard_cmd, &desc);
+}
+
+static void its_send_invall(struct its_node *its, struct its_collection *col)
+{
+       struct its_cmd_desc desc;
+
+       desc.its_invall_cmd.col = col;
+
+       its_send_single_command(its, its_build_invall_cmd, &desc);
+}
index 040615a..21c9d70 100644 (file)
 #define GICR_MOVALLR                   0x0110
 #define GICR_PIDR2                     GICD_PIDR2
 
+#define GICR_CTLR_ENABLE_LPIS          (1UL << 0)
+
+#define GICR_TYPER_CPU_NUMBER(r)       (((r) >> 8) & 0xffff)
+
 #define GICR_WAKER_ProcessorSleep      (1U << 1)
 #define GICR_WAKER_ChildrenAsleep      (1U << 2)
 
+#define GICR_PROPBASER_NonShareable    (0U << 10)
+#define GICR_PROPBASER_InnerShareable  (1U << 10)
+#define GICR_PROPBASER_OuterShareable  (2U << 10)
+#define GICR_PROPBASER_SHAREABILITY_MASK (3UL << 10)
+#define GICR_PROPBASER_nCnB            (0U << 7)
+#define GICR_PROPBASER_nC              (1U << 7)
+#define GICR_PROPBASER_RaWt            (2U << 7)
+#define GICR_PROPBASER_RaWb            (3U << 7)
+#define GICR_PROPBASER_WaWt            (4U << 7)
+#define GICR_PROPBASER_WaWb            (5U << 7)
+#define GICR_PROPBASER_RaWaWt          (6U << 7)
+#define GICR_PROPBASER_RaWaWb          (7U << 7)
+#define GICR_PROPBASER_IDBITS_MASK     (0x1f)
+
 /*
  * Re-Distributor registers, offsets from SGI_base
  */
 #define GICR_IPRIORITYR0               GICD_IPRIORITYR
 #define GICR_ICFGR0                    GICD_ICFGR
 
+#define GICR_TYPER_PLPIS               (1U << 0)
 #define GICR_TYPER_VLPIS               (1U << 1)
 #define GICR_TYPER_LAST                        (1U << 4)
 
+#define LPI_PROP_GROUP1                        (1 << 1)
+#define LPI_PROP_ENABLED               (1 << 0)
+
+/*
+ * ITS registers, offsets from ITS_base
+ */
+#define GITS_CTLR                      0x0000
+#define GITS_IIDR                      0x0004
+#define GITS_TYPER                     0x0008
+#define GITS_CBASER                    0x0080
+#define GITS_CWRITER                   0x0088
+#define GITS_CREADR                    0x0090
+#define GITS_BASER                     0x0100
+#define GITS_PIDR2                     GICR_PIDR2
+
+#define GITS_TRANSLATER                        0x10040
+
+#define GITS_TYPER_PTA                 (1UL << 19)
+
+#define GITS_CBASER_VALID              (1UL << 63)
+#define GITS_CBASER_nCnB               (0UL << 59)
+#define GITS_CBASER_nC                 (1UL << 59)
+#define GITS_CBASER_RaWt               (2UL << 59)
+#define GITS_CBASER_RaWb               (3UL << 59)
+#define GITS_CBASER_WaWt               (4UL << 59)
+#define GITS_CBASER_WaWb               (5UL << 59)
+#define GITS_CBASER_RaWaWt             (6UL << 59)
+#define GITS_CBASER_RaWaWb             (7UL << 59)
+#define GITS_CBASER_NonShareable       (0UL << 10)
+#define GITS_CBASER_InnerShareable     (1UL << 10)
+#define GITS_CBASER_OuterShareable     (2UL << 10)
+#define GITS_CBASER_SHAREABILITY_MASK  (3UL << 10)
+
+#define GITS_BASER_NR_REGS             8
+
+#define GITS_BASER_VALID               (1UL << 63)
+#define GITS_BASER_nCnB                        (0UL << 59)
+#define GITS_BASER_nC                  (1UL << 59)
+#define GITS_BASER_RaWt                        (2UL << 59)
+#define GITS_BASER_RaWb                        (3UL << 59)
+#define GITS_BASER_WaWt                        (4UL << 59)
+#define GITS_BASER_WaWb                        (5UL << 59)
+#define GITS_BASER_RaWaWt              (6UL << 59)
+#define GITS_BASER_RaWaWb              (7UL << 59)
+#define GITS_BASER_TYPE_SHIFT          (56)
+#define GITS_BASER_TYPE(r)             (((r) >> GITS_BASER_TYPE_SHIFT) & 7)
+#define GITS_BASER_ENTRY_SIZE_SHIFT    (48)
+#define GITS_BASER_ENTRY_SIZE(r)       ((((r) >> GITS_BASER_ENTRY_SIZE_SHIFT) & 0xff) + 1)
+#define GITS_BASER_NonShareable                (0UL << 10)
+#define GITS_BASER_InnerShareable      (1UL << 10)
+#define GITS_BASER_OuterShareable      (2UL << 10)
+#define GITS_BASER_SHAREABILITY_SHIFT  (10)
+#define GITS_BASER_SHAREABILITY_MASK   (3UL << GITS_BASER_SHAREABILITY_SHIFT)
+#define GITS_BASER_PAGE_SIZE_SHIFT     (8)
+#define GITS_BASER_PAGE_SIZE_4K                (0UL << GITS_BASER_PAGE_SIZE_SHIFT)
+#define GITS_BASER_PAGE_SIZE_16K       (1UL << GITS_BASER_PAGE_SIZE_SHIFT)
+#define GITS_BASER_PAGE_SIZE_64K       (2UL << GITS_BASER_PAGE_SIZE_SHIFT)
+#define GITS_BASER_PAGE_SIZE_MASK      (3UL << GITS_BASER_PAGE_SIZE_SHIFT)
+
+#define GITS_BASER_TYPE_NONE           0
+#define GITS_BASER_TYPE_DEVICE         1
+#define GITS_BASER_TYPE_VCPU           2
+#define GITS_BASER_TYPE_CPU            3
+#define GITS_BASER_TYPE_COLLECTION     4
+#define GITS_BASER_TYPE_RESERVED5      5
+#define GITS_BASER_TYPE_RESERVED6      6
+#define GITS_BASER_TYPE_RESERVED7      7
+
+/*
+ * ITS commands
+ */
+#define GITS_CMD_MAPD                  0x08
+#define GITS_CMD_MAPC                  0x09
+#define GITS_CMD_MAPVI                 0x0a
+#define GITS_CMD_MOVI                  0x01
+#define GITS_CMD_DISCARD               0x0f
+#define GITS_CMD_INV                   0x0c
+#define GITS_CMD_MOVALL                        0x0e
+#define GITS_CMD_INVALL                        0x0d
+#define GITS_CMD_INT                   0x03
+#define GITS_CMD_CLEAR                 0x04
+#define GITS_CMD_SYNC                  0x05
+
 /*
  * CPU interface registers
  */