[kvmfornfv.git] / kernel / drivers / irqchip / irq-gic-v3-its.c

/*
 * 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)

#define RDIST_FLAGS_PROPBASE_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;
};

static LIST_HEAD(its_nodes);
static DEFINE_SPINLOCK(its_lock);
static struct device_node *gic_root_node;
static struct rdists *gic_rdists;

#define gic_data_rdist()                (raw_cpu_ptr(gic_rdists->rdist))
#define gic_data_rdist_rd_base()        (gic_data_rdist()->rd_base)

/*
 * 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] &= BIT_ULL(32) - 1;
        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 = ilog2(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;
        unsigned long flags;

        raw_spin_lock_irqsave(&its->lock, flags);

        cmd = its_allocate_entry(its);
        if (!cmd) {             /* We're soooooo screewed... */
                pr_err_ratelimited("ITS can't allocate, dropping command\n");
                raw_spin_unlock_irqrestore(&its->lock, flags);
                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_irqrestore(&its->lock, flags);

        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);
}

/*
 * irqchip functions - assumes MSI, mostly.
 */

static inline u32 its_get_event_id(struct irq_data *d)
{
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        return d->hwirq - its_dev->lpi_base;
}

static void lpi_set_config(struct irq_data *d, bool enable)
{
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        irq_hw_number_t hwirq = d->hwirq;
        u32 id = its_get_event_id(d);
        u8 *cfg = page_address(gic_rdists->prop_page) + hwirq - 8192;

        if (enable)
                *cfg |= LPI_PROP_ENABLED;
        else
                *cfg &= ~LPI_PROP_ENABLED;

        /*
         * Make the above write visible to the redistributors.
         * And yes, we're flushing exactly: One. Single. Byte.
         * Humpf...
         */
        if (gic_rdists->flags & RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING)
                __flush_dcache_area(cfg, sizeof(*cfg));
        else
                dsb(ishst);
        its_send_inv(its_dev, id);
}

static void its_mask_irq(struct irq_data *d)
{
        lpi_set_config(d, false);
}

static void its_unmask_irq(struct irq_data *d)
{
        lpi_set_config(d, true);
}

static void its_eoi_irq(struct irq_data *d)
{
        gic_write_eoir(d->hwirq);
}

static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
                            bool force)
{
        unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask);
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        struct its_collection *target_col;
        u32 id = its_get_event_id(d);

        if (cpu >= nr_cpu_ids)
                return -EINVAL;

        target_col = &its_dev->its->collections[cpu];
        its_send_movi(its_dev, target_col, id);
        its_dev->collection = target_col;

        return IRQ_SET_MASK_OK_DONE;
}

static void its_irq_compose_msi_msg(struct irq_data *d, struct msi_msg *msg)
{
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        struct its_node *its;
        u64 addr;

        its = its_dev->its;
        addr = its->phys_base + GITS_TRANSLATER;

        msg->address_lo         = addr & ((1UL << 32) - 1);
        msg->address_hi         = addr >> 32;
        msg->data               = its_get_event_id(d);
}

static struct irq_chip its_irq_chip = {
        .name                   = "ITS",
        .irq_mask               = its_mask_irq,
        .irq_unmask             = its_unmask_irq,
        .irq_eoi                = its_eoi_irq,
        .irq_set_affinity       = its_set_affinity,
        .irq_compose_msi_msg    = its_irq_compose_msi_msg,
};

static void its_mask_msi_irq(struct irq_data *d)
{
        pci_msi_mask_irq(d);
        irq_chip_mask_parent(d);
}

static void its_unmask_msi_irq(struct irq_data *d)
{
        pci_msi_unmask_irq(d);
        irq_chip_unmask_parent(d);
}

static struct irq_chip its_msi_irq_chip = {
        .name                   = "ITS-MSI",
        .irq_unmask             = its_unmask_msi_irq,
        .irq_mask               = its_mask_msi_irq,
        .irq_eoi                = irq_chip_eoi_parent,
        .irq_write_msi_msg      = pci_msi_domain_write_msg,
};

/*
 * How we allocate LPIs:
 *
 * The GIC has id_bits bits for interrupt identifiers. From there, we
 * must subtract 8192 which are reserved for SGIs/PPIs/SPIs. Then, as
 * we allocate LPIs by chunks of 32, we can shift the whole thing by 5
 * bits to the right.
 *
 * This gives us (((1UL << id_bits) - 8192) >> 5) possible allocations.
 */
#define IRQS_PER_CHUNK_SHIFT    5
#define IRQS_PER_CHUNK          (1 << IRQS_PER_CHUNK_SHIFT)

static unsigned long *lpi_bitmap;
static u32 lpi_chunks;
static DEFINE_SPINLOCK(lpi_lock);

static int its_lpi_to_chunk(int lpi)
{
        return (lpi - 8192) >> IRQS_PER_CHUNK_SHIFT;
}

static int its_chunk_to_lpi(int chunk)
{
        return (chunk << IRQS_PER_CHUNK_SHIFT) + 8192;
}

static int its_lpi_init(u32 id_bits)
{
        lpi_chunks = its_lpi_to_chunk(1UL << id_bits);

        lpi_bitmap = kzalloc(BITS_TO_LONGS(lpi_chunks) * sizeof(long),
                             GFP_KERNEL);
        if (!lpi_bitmap) {
                lpi_chunks = 0;
                return -ENOMEM;
        }

        pr_info("ITS: Allocated %d chunks for LPIs\n", (int)lpi_chunks);
        return 0;
}

static unsigned long *its_lpi_alloc_chunks(int nr_irqs, int *base, int *nr_ids)
{
        unsigned long *bitmap = NULL;
        int chunk_id;
        int nr_chunks;
        int i;

        nr_chunks = DIV_ROUND_UP(nr_irqs, IRQS_PER_CHUNK);

        spin_lock(&lpi_lock);

        do {
                chunk_id = bitmap_find_next_zero_area(lpi_bitmap, lpi_chunks,
                                                      0, nr_chunks, 0);
                if (chunk_id < lpi_chunks)
                        break;

                nr_chunks--;
        } while (nr_chunks > 0);

        if (!nr_chunks)
                goto out;

        bitmap = kzalloc(BITS_TO_LONGS(nr_chunks * IRQS_PER_CHUNK) * sizeof (long),
                         GFP_ATOMIC);
        if (!bitmap)
                goto out;

        for (i = 0; i < nr_chunks; i++)
                set_bit(chunk_id + i, lpi_bitmap);

        *base = its_chunk_to_lpi(chunk_id);
        *nr_ids = nr_chunks * IRQS_PER_CHUNK;

out:
        spin_unlock(&lpi_lock);

        return bitmap;
}

static void its_lpi_free(unsigned long *bitmap, int base, int nr_ids)
{
        int lpi;

        spin_lock(&lpi_lock);

        for (lpi = base; lpi < (base + nr_ids); lpi += IRQS_PER_CHUNK) {
                int chunk = its_lpi_to_chunk(lpi);
                BUG_ON(chunk > lpi_chunks);
                if (test_bit(chunk, lpi_bitmap)) {
                        clear_bit(chunk, lpi_bitmap);
                } else {
                        pr_err("Bad LPI chunk %d\n", chunk);
                }
        }

        spin_unlock(&lpi_lock);

        kfree(bitmap);
}

/*
 * We allocate 64kB for PROPBASE. That gives us at most 64K LPIs to
 * deal with (one configuration byte per interrupt). PENDBASE has to
 * be 64kB aligned (one bit per LPI, plus 8192 bits for SPI/PPI/SGI).
 */
#define LPI_PROPBASE_SZ         SZ_64K
#define LPI_PENDBASE_SZ         (LPI_PROPBASE_SZ / 8 + SZ_1K)

/*
 * This is how many bits of ID we need, including the useless ones.
 */
#define LPI_NRBITS              ilog2(LPI_PROPBASE_SZ + SZ_8K)

#define LPI_PROP_DEFAULT_PRIO   0xa0

static int __init its_alloc_lpi_tables(void)
{
        phys_addr_t paddr;

        gic_rdists->prop_page = alloc_pages(GFP_NOWAIT,
                                           get_order(LPI_PROPBASE_SZ));
        if (!gic_rdists->prop_page) {
                pr_err("Failed to allocate PROPBASE\n");
                return -ENOMEM;
        }

        paddr = page_to_phys(gic_rdists->prop_page);
        pr_info("GIC: using LPI property table @%pa\n", &paddr);

        /* Priority 0xa0, Group-1, disabled */
        memset(page_address(gic_rdists->prop_page),
               LPI_PROP_DEFAULT_PRIO | LPI_PROP_GROUP1,
               LPI_PROPBASE_SZ);

        /* Make sure the GIC will observe the written configuration */
        __flush_dcache_area(page_address(gic_rdists->prop_page), LPI_PROPBASE_SZ);

        return 0;
}

static const char *its_base_type_string[] = {
        [GITS_BASER_TYPE_DEVICE]        = "Devices",
        [GITS_BASER_TYPE_VCPU]          = "Virtual CPUs",
        [GITS_BASER_TYPE_CPU]           = "Physical CPUs",
        [GITS_BASER_TYPE_COLLECTION]    = "Interrupt Collections",
        [GITS_BASER_TYPE_RESERVED5]     = "Reserved (5)",
        [GITS_BASER_TYPE_RESERVED6]     = "Reserved (6)",
        [GITS_BASER_TYPE_RESERVED7]     = "Reserved (7)",
};

static void its_free_tables(struct its_node *its)
{
        int i;

        for (i = 0; i < GITS_BASER_NR_REGS; i++) {
                if (its->tables[i]) {
                        free_page((unsigned long)its->tables[i]);
                        its->tables[i] = NULL;
                }
        }
}

static int its_alloc_tables(struct its_node *its)
{
        int err;
        int i;
        int psz = SZ_64K;
        u64 shr = GITS_BASER_InnerShareable;
        u64 cache = GITS_BASER_WaWb;

        for (i = 0; i < GITS_BASER_NR_REGS; i++) {
                u64 val = readq_relaxed(its->base + GITS_BASER + i * 8);
                u64 type = GITS_BASER_TYPE(val);
                u64 entry_size = GITS_BASER_ENTRY_SIZE(val);
                int order = get_order(psz);
                int alloc_size;
                u64 tmp;
                void *base;

                if (type == GITS_BASER_TYPE_NONE)
                        continue;

                /*
                 * Allocate as many entries as required to fit the
                 * range of device IDs that the ITS can grok... The ID
                 * space being incredibly sparse, this results in a
                 * massive waste of memory.
                 *
                 * For other tables, only allocate a single page.
                 */
                if (type == GITS_BASER_TYPE_DEVICE) {
                        u64 typer = readq_relaxed(its->base + GITS_TYPER);
                        u32 ids = GITS_TYPER_DEVBITS(typer);

                        /*
                         * 'order' was initialized earlier to the default page
                         * granule of the the ITS.  We can't have an allocation
                         * smaller than that.  If the requested allocation
                         * is smaller, round up to the default page granule.
                         */
                        order = max(get_order((1UL << ids) * entry_size),
                                    order);
                        if (order >= MAX_ORDER) {
                                order = MAX_ORDER - 1;
                                pr_warn("%s: Device Table too large, reduce its page order to %u\n",
                                        its->msi_chip.of_node->full_name, order);
                        }
                }

                alloc_size = (1 << order) * PAGE_SIZE;
                base = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
                if (!base) {
                        err = -ENOMEM;
                        goto out_free;
                }

                its->tables[i] = base;

retry_baser:
                val = (virt_to_phys(base)                                |
                       (type << GITS_BASER_TYPE_SHIFT)                   |
                       ((entry_size - 1) << GITS_BASER_ENTRY_SIZE_SHIFT) |
                       cache                                             |
                       shr                                               |
                       GITS_BASER_VALID);

                switch (psz) {
                case SZ_4K:
                        val |= GITS_BASER_PAGE_SIZE_4K;
                        break;
                case SZ_16K:
                        val |= GITS_BASER_PAGE_SIZE_16K;
                        break;
                case SZ_64K:
                        val |= GITS_BASER_PAGE_SIZE_64K;
                        break;
                }

                val |= (alloc_size / psz) - 1;

                writeq_relaxed(val, its->base + GITS_BASER + i * 8);
                tmp = readq_relaxed(its->base + GITS_BASER + i * 8);

                if ((val ^ tmp) & GITS_BASER_SHAREABILITY_MASK) {
                        /*
                         * Shareability didn't stick. Just use
                         * whatever the read reported, which is likely
                         * to be the only thing this redistributor
                         * supports. If that's zero, make it
                         * non-cacheable as well.
                         */
                        shr = tmp & GITS_BASER_SHAREABILITY_MASK;
                        if (!shr)
                                cache = GITS_BASER_nC;
                        goto retry_baser;
                }

                if ((val ^ tmp) & GITS_BASER_PAGE_SIZE_MASK) {
                        /*
                         * Page size didn't stick. Let's try a smaller
                         * size and retry. If we reach 4K, then
                         * something is horribly wrong...
                         */
                        switch (psz) {
                        case SZ_16K:
                                psz = SZ_4K;
                                goto retry_baser;
                        case SZ_64K:
                                psz = SZ_16K;
                                goto retry_baser;
                        }
                }

                if (val != tmp) {
                        pr_err("ITS: %s: GITS_BASER%d doesn't stick: %lx %lx\n",
                               its->msi_chip.of_node->full_name, i,
                               (unsigned long) val, (unsigned long) tmp);
                        err = -ENXIO;
                        goto out_free;
                }

                pr_info("ITS: allocated %d %s @%lx (psz %dK, shr %d)\n",
                        (int)(alloc_size / entry_size),
                        its_base_type_string[type],
                        (unsigned long)virt_to_phys(base),
                        psz / SZ_1K, (int)shr >> GITS_BASER_SHAREABILITY_SHIFT);
        }

        return 0;

out_free:
        its_free_tables(its);

        return err;
}

static int its_alloc_collections(struct its_node *its)
{
        its->collections = kzalloc(nr_cpu_ids * sizeof(*its->collections),
                                   GFP_KERNEL);
        if (!its->collections)
                return -ENOMEM;

        return 0;
}

static void its_cpu_init_lpis(void)
{
        void __iomem *rbase = gic_data_rdist_rd_base();
        struct page *pend_page;
        u64 val, tmp;

        /* If we didn't allocate the pending table yet, do it now */
        pend_page = gic_data_rdist()->pend_page;
        if (!pend_page) {
                phys_addr_t paddr;
                /*
                 * The pending pages have to be at least 64kB aligned,
                 * hence the 'max(LPI_PENDBASE_SZ, SZ_64K)' below.
                 */
                pend_page = alloc_pages(GFP_NOWAIT | __GFP_ZERO,
                                        get_order(max(LPI_PENDBASE_SZ, SZ_64K)));
                if (!pend_page) {
                        pr_err("Failed to allocate PENDBASE for CPU%d\n",
                               smp_processor_id());
                        return;
                }

                /* Make sure the GIC will observe the zero-ed page */
                __flush_dcache_area(page_address(pend_page), LPI_PENDBASE_SZ);

                paddr = page_to_phys(pend_page);
                pr_info("CPU%d: using LPI pending table @%pa\n",
                        smp_processor_id(), &paddr);
                gic_data_rdist()->pend_page = pend_page;
        }

        /* Disable LPIs */
        val = readl_relaxed(rbase + GICR_CTLR);
        val &= ~GICR_CTLR_ENABLE_LPIS;
        writel_relaxed(val, rbase + GICR_CTLR);

        /*
         * Make sure any change to the table is observable by the GIC.
         */
        dsb(sy);

        /* set PROPBASE */
        val = (page_to_phys(gic_rdists->prop_page) |
               GICR_PROPBASER_InnerShareable |
               GICR_PROPBASER_WaWb |
               ((LPI_NRBITS - 1) & GICR_PROPBASER_IDBITS_MASK));

        writeq_relaxed(val, rbase + GICR_PROPBASER);
        tmp = readq_relaxed(rbase + GICR_PROPBASER);

        if ((tmp ^ val) & GICR_PROPBASER_SHAREABILITY_MASK) {
                if (!(tmp & GICR_PROPBASER_SHAREABILITY_MASK)) {
                        /*
                         * The HW reports non-shareable, we must
                         * remove the cacheability attributes as
                         * well.
                         */
                        val &= ~(GICR_PROPBASER_SHAREABILITY_MASK |
                                 GICR_PROPBASER_CACHEABILITY_MASK);
                        val |= GICR_PROPBASER_nC;
                        writeq_relaxed(val, rbase + GICR_PROPBASER);
                }
                pr_info_once("GIC: using cache flushing for LPI property table\n");
                gic_rdists->flags |= RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING;
        }

        /* set PENDBASE */
        val = (page_to_phys(pend_page) |
               GICR_PENDBASER_InnerShareable |
               GICR_PENDBASER_WaWb);

        writeq_relaxed(val, rbase + GICR_PENDBASER);
        tmp = readq_relaxed(rbase + GICR_PENDBASER);

        if (!(tmp & GICR_PENDBASER_SHAREABILITY_MASK)) {
                /*
                 * The HW reports non-shareable, we must remove the
                 * cacheability attributes as well.
                 */
                val &= ~(GICR_PENDBASER_SHAREABILITY_MASK |
                         GICR_PENDBASER_CACHEABILITY_MASK);
                val |= GICR_PENDBASER_nC;
                writeq_relaxed(val, rbase + GICR_PENDBASER);
        }

        /* Enable LPIs */
        val = readl_relaxed(rbase + GICR_CTLR);
        val |= GICR_CTLR_ENABLE_LPIS;
        writel_relaxed(val, rbase + GICR_CTLR);

        /* Make sure the GIC has seen the above */
        dsb(sy);
}

static void its_cpu_init_collection(void)
{
        struct its_node *its;
        int cpu;

        spin_lock(&its_lock);
        cpu = smp_processor_id();

        list_for_each_entry(its, &its_nodes, entry) {
                u64 target;

                /*
                 * We now have to bind each collection to its target
                 * redistributor.
                 */
                if (readq_relaxed(its->base + GITS_TYPER) & GITS_TYPER_PTA) {
                        /*
                         * This ITS wants the physical address of the
                         * redistributor.
                         */
                        target = gic_data_rdist()->phys_base;
                } else {
                        /*
                         * This ITS wants a linear CPU number.
                         */
                        target = readq_relaxed(gic_data_rdist_rd_base() + GICR_TYPER);
                        target = GICR_TYPER_CPU_NUMBER(target) << 16;
                }

                /* Perform collection mapping */
                its->collections[cpu].target_address = target;
                its->collections[cpu].col_id = cpu;

                its_send_mapc(its, &its->collections[cpu], 1);
                its_send_invall(its, &its->collections[cpu]);
        }

        spin_unlock(&its_lock);
}

static struct its_device *its_find_device(struct its_node *its, u32 dev_id)
{
        struct its_device *its_dev = NULL, *tmp;
        unsigned long flags;

        raw_spin_lock_irqsave(&its->lock, flags);

        list_for_each_entry(tmp, &its->its_device_list, entry) {
                if (tmp->device_id == dev_id) {
                        its_dev = tmp;
                        break;
                }
        }

        raw_spin_unlock_irqrestore(&its->lock, flags);

        return its_dev;
}

static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
                                            int nvecs)
{
        struct its_device *dev;
        unsigned long *lpi_map;
        unsigned long flags;
        void *itt;
        int lpi_base;
        int nr_lpis;
        int nr_ites;
        int cpu;
        int sz;

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        /*
         * At least one bit of EventID is being used, hence a minimum
         * of two entries. No, the architecture doesn't let you
         * express an ITT with a single entry.
         */
        nr_ites = max(2UL, roundup_pow_of_two(nvecs));
        sz = nr_ites * its->ite_size;
        sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
        itt = kzalloc(sz, GFP_KERNEL);
        lpi_map = its_lpi_alloc_chunks(nvecs, &lpi_base, &nr_lpis);

        if (!dev || !itt || !lpi_map) {
                kfree(dev);
                kfree(itt);
                kfree(lpi_map);
                return NULL;
        }

        dev->its = its;
        dev->itt = itt;
        dev->nr_ites = nr_ites;
        dev->lpi_map = lpi_map;
        dev->lpi_base = lpi_base;
        dev->nr_lpis = nr_lpis;
        dev->device_id = dev_id;
        INIT_LIST_HEAD(&dev->entry);

        raw_spin_lock_irqsave(&its->lock, flags);
        list_add(&dev->entry, &its->its_device_list);
        raw_spin_unlock_irqrestore(&its->lock, flags);

        /* Bind the device to the first possible CPU */
        cpu = cpumask_first(cpu_online_mask);
        dev->collection = &its->collections[cpu];

        /* Map device to its ITT */
        its_send_mapd(dev, 1);

        return dev;
}

static void its_free_device(struct its_device *its_dev)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&its_dev->its->lock, flags);
        list_del(&its_dev->entry);
        raw_spin_unlock_irqrestore(&its_dev->its->lock, flags);
        kfree(its_dev->itt);
        kfree(its_dev);
}

static int its_alloc_device_irq(struct its_device *dev, irq_hw_number_t *hwirq)
{
        int idx;

        idx = find_first_zero_bit(dev->lpi_map, dev->nr_lpis);
        if (idx == dev->nr_lpis)
                return -ENOSPC;

        *hwirq = dev->lpi_base + idx;
        set_bit(idx, dev->lpi_map);

        return 0;
}

struct its_pci_alias {
        struct pci_dev  *pdev;
        u32             dev_id;
        u32             count;
};

static int its_pci_msi_vec_count(struct pci_dev *pdev)
{
        int msi, msix;

        msi = max(pci_msi_vec_count(pdev), 0);
        msix = max(pci_msix_vec_count(pdev), 0);

        return max(msi, msix);
}

static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
{
        struct its_pci_alias *dev_alias = data;

        dev_alias->dev_id = alias;
        if (pdev != dev_alias->pdev)
                dev_alias->count += its_pci_msi_vec_count(dev_alias->pdev);

        return 0;
}

static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
                           int nvec, msi_alloc_info_t *info)
{
        struct pci_dev *pdev;
        struct its_node *its;
        struct its_device *its_dev;
        struct its_pci_alias dev_alias;

        if (!dev_is_pci(dev))
                return -EINVAL;

        pdev = to_pci_dev(dev);
        dev_alias.pdev = pdev;
        dev_alias.count = nvec;

        pci_for_each_dma_alias(pdev, its_get_pci_alias, &dev_alias);
        its = domain->parent->host_data;

        its_dev = its_find_device(its, dev_alias.dev_id);
        if (its_dev) {
                /*
                 * We already have seen this ID, probably through
                 * another alias (PCI bridge of some sort). No need to
                 * create the device.
                 */
                dev_dbg(dev, "Reusing ITT for devID %x\n", dev_alias.dev_id);
                goto out;
        }

        its_dev = its_create_device(its, dev_alias.dev_id, dev_alias.count);
        if (!its_dev)
                return -ENOMEM;

        dev_dbg(&pdev->dev, "ITT %d entries, %d bits\n",
                dev_alias.count, ilog2(dev_alias.count));
out:
        info->scratchpad[0].ptr = its_dev;
        info->scratchpad[1].ptr = dev;
        return 0;
}

static struct msi_domain_ops its_pci_msi_ops = {
        .msi_prepare    = its_msi_prepare,
};

static struct msi_domain_info its_pci_msi_domain_info = {
        .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
                   MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
        .ops    = &its_pci_msi_ops,
        .chip   = &its_msi_irq_chip,
};

static int its_irq_gic_domain_alloc(struct irq_domain *domain,
                                    unsigned int virq,
                                    irq_hw_number_t hwirq)
{
        struct of_phandle_args args;

        args.np = domain->parent->of_node;
        args.args_count = 3;
        args.args[0] = GIC_IRQ_TYPE_LPI;
        args.args[1] = hwirq;
        args.args[2] = IRQ_TYPE_EDGE_RISING;

        return irq_domain_alloc_irqs_parent(domain, virq, 1, &args);
}

static int its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
                                unsigned int nr_irqs, void *args)
{
        msi_alloc_info_t *info = args;
        struct its_device *its_dev = info->scratchpad[0].ptr;
        irq_hw_number_t hwirq;
        int err;
        int i;

        for (i = 0; i < nr_irqs; i++) {
                err = its_alloc_device_irq(its_dev, &hwirq);
                if (err)
                        return err;

                err = its_irq_gic_domain_alloc(domain, virq + i, hwirq);
                if (err)
                        return err;

                irq_domain_set_hwirq_and_chip(domain, virq + i,
                                              hwirq, &its_irq_chip, its_dev);
                dev_dbg(info->scratchpad[1].ptr, "ID:%d pID:%d vID:%d\n",
                        (int)(hwirq - its_dev->lpi_base), (int)hwirq, virq + i);
        }

        return 0;
}

static void its_irq_domain_activate(struct irq_domain *domain,
                                    struct irq_data *d)
{
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        u32 event = its_get_event_id(d);

        /* Map the GIC IRQ and event to the device */
        its_send_mapvi(its_dev, d->hwirq, event);
}

static void its_irq_domain_deactivate(struct irq_domain *domain,
                                      struct irq_data *d)
{
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        u32 event = its_get_event_id(d);

        /* Stop the delivery of interrupts */
        its_send_discard(its_dev, event);
}

static void its_irq_domain_free(struct irq_domain *domain, unsigned int virq,
                                unsigned int nr_irqs)
{
        struct irq_data *d = irq_domain_get_irq_data(domain, virq);
        struct its_device *its_dev = irq_data_get_irq_chip_data(d);
        int i;

        for (i = 0; i < nr_irqs; i++) {
                struct irq_data *data = irq_domain_get_irq_data(domain,
                                                                virq + i);
                u32 event = its_get_event_id(data);

                /* Mark interrupt index as unused */
                clear_bit(event, its_dev->lpi_map);

                /* Nuke the entry in the domain */
                irq_domain_reset_irq_data(data);
        }

        /* If all interrupts have been freed, start mopping the floor */
        if (bitmap_empty(its_dev->lpi_map, its_dev->nr_lpis)) {
                its_lpi_free(its_dev->lpi_map,
                             its_dev->lpi_base,
                             its_dev->nr_lpis);

                /* Unmap device/itt */
                its_send_mapd(its_dev, 0);
                its_free_device(its_dev);
        }

        irq_domain_free_irqs_parent(domain, virq, nr_irqs);
}

static const struct irq_domain_ops its_domain_ops = {
        .alloc                  = its_irq_domain_alloc,
        .free                   = its_irq_domain_free,
        .activate               = its_irq_domain_activate,
        .deactivate             = its_irq_domain_deactivate,
};

static int its_force_quiescent(void __iomem *base)
{
        u32 count = 1000000;    /* 1s */
        u32 val;

        val = readl_relaxed(base + GITS_CTLR);
        if (val & GITS_CTLR_QUIESCENT)
                return 0;

        /* Disable the generation of all interrupts to this ITS */
        val &= ~GITS_CTLR_ENABLE;
        writel_relaxed(val, base + GITS_CTLR);

        /* Poll GITS_CTLR and wait until ITS becomes quiescent */
        while (1) {
                val = readl_relaxed(base + GITS_CTLR);
                if (val & GITS_CTLR_QUIESCENT)
                        return 0;

                count--;
                if (!count)
                        return -EBUSY;

                cpu_relax();
                udelay(1);
        }
}

static int its_probe(struct device_node *node, struct irq_domain *parent)
{
        struct resource res;
        struct its_node *its;
        void __iomem *its_base;
        u32 val;
        u64 baser, tmp;
        int err;

        err = of_address_to_resource(node, 0, &res);
        if (err) {
                pr_warn("%s: no regs?\n", node->full_name);
                return -ENXIO;
        }

        its_base = ioremap(res.start, resource_size(&res));
        if (!its_base) {
                pr_warn("%s: unable to map registers\n", node->full_name);
                return -ENOMEM;
        }

        val = readl_relaxed(its_base + GITS_PIDR2) & GIC_PIDR2_ARCH_MASK;
        if (val != 0x30 && val != 0x40) {
                pr_warn("%s: no ITS detected, giving up\n", node->full_name);
                err = -ENODEV;
                goto out_unmap;
        }

        err = its_force_quiescent(its_base);
        if (err) {
                pr_warn("%s: failed to quiesce, giving up\n",
                        node->full_name);
                goto out_unmap;
        }

        pr_info("ITS: %s\n", node->full_name);

        its = kzalloc(sizeof(*its), GFP_KERNEL);
        if (!its) {
                err = -ENOMEM;
                goto out_unmap;
        }

        raw_spin_lock_init(&its->lock);
        INIT_LIST_HEAD(&its->entry);
        INIT_LIST_HEAD(&its->its_device_list);
        its->base = its_base;
        its->phys_base = res.start;
        its->msi_chip.of_node = node;
        its->ite_size = ((readl_relaxed(its_base + GITS_TYPER) >> 4) & 0xf) + 1;

        its->cmd_base = kzalloc(ITS_CMD_QUEUE_SZ, GFP_KERNEL);
        if (!its->cmd_base) {
                err = -ENOMEM;
                goto out_free_its;
        }
        its->cmd_write = its->cmd_base;

        err = its_alloc_tables(its);
        if (err)
                goto out_free_cmd;

        err = its_alloc_collections(its);
        if (err)
                goto out_free_tables;

        baser = (virt_to_phys(its->cmd_base)    |
                 GITS_CBASER_WaWb               |
                 GITS_CBASER_InnerShareable     |
                 (ITS_CMD_QUEUE_SZ / SZ_4K - 1) |
                 GITS_CBASER_VALID);

        writeq_relaxed(baser, its->base + GITS_CBASER);
        tmp = readq_relaxed(its->base + GITS_CBASER);

        if ((tmp ^ baser) & GITS_CBASER_SHAREABILITY_MASK) {
                if (!(tmp & GITS_CBASER_SHAREABILITY_MASK)) {
                        /*
                         * The HW reports non-shareable, we must
                         * remove the cacheability attributes as
                         * well.
                         */
                        baser &= ~(GITS_CBASER_SHAREABILITY_MASK |
                                   GITS_CBASER_CACHEABILITY_MASK);
                        baser |= GITS_CBASER_nC;
                        writeq_relaxed(baser, its->base + GITS_CBASER);
                }
                pr_info("ITS: using cache flushing for cmd queue\n");
                its->flags |= ITS_FLAGS_CMDQ_NEEDS_FLUSHING;
        }

        writeq_relaxed(0, its->base + GITS_CWRITER);
        writel_relaxed(GITS_CTLR_ENABLE, its->base + GITS_CTLR);

        if (of_property_read_bool(its->msi_chip.of_node, "msi-controller")) {
                its->domain = irq_domain_add_tree(NULL, &its_domain_ops, its);
                if (!its->domain) {
                        err = -ENOMEM;
                        goto out_free_tables;
                }

                its->domain->parent = parent;

                its->msi_chip.domain = pci_msi_create_irq_domain(node,
                                                                 &its_pci_msi_domain_info,
                                                                 its->domain);
                if (!its->msi_chip.domain) {
                        err = -ENOMEM;
                        goto out_free_domains;
                }

                err = of_pci_msi_chip_add(&its->msi_chip);
                if (err)
                        goto out_free_domains;
        }

        spin_lock(&its_lock);
        list_add(&its->entry, &its_nodes);
        spin_unlock(&its_lock);

        return 0;

out_free_domains:
        if (its->msi_chip.domain)
                irq_domain_remove(its->msi_chip.domain);
        if (its->domain)
                irq_domain_remove(its->domain);
out_free_tables:
        its_free_tables(its);
out_free_cmd:
        kfree(its->cmd_base);
out_free_its:
        kfree(its);
out_unmap:
        iounmap(its_base);
        pr_err("ITS: failed probing %s (%d)\n", node->full_name, err);
        return err;
}

static bool gic_rdists_supports_plpis(void)
{
        return !!(readl_relaxed(gic_data_rdist_rd_base() + GICR_TYPER) & GICR_TYPER_PLPIS);
}

int its_cpu_init(void)
{
        if (!list_empty(&its_nodes)) {
                if (!gic_rdists_supports_plpis()) {
                        pr_info("CPU%d: LPIs not supported\n", smp_processor_id());
                        return -ENXIO;
                }
                its_cpu_init_lpis();
                its_cpu_init_collection();
        }

        return 0;
}

static struct of_device_id its_device_id[] = {
        {       .compatible     = "arm,gic-v3-its",     },
        {},
};

int its_init(struct device_node *node, struct rdists *rdists,
             struct irq_domain *parent_domain)
{
        struct device_node *np;

        for (np = of_find_matching_node(node, its_device_id); np;
             np = of_find_matching_node(np, its_device_id)) {
                its_probe(np, parent_domain);
        }

        if (list_empty(&its_nodes)) {
                pr_warn("ITS: No ITS available, not enabling LPIs\n");
                return -ENXIO;
        }

        gic_rdists = rdists;
        gic_root_node = node;

        its_alloc_lpi_tables();
        its_lpi_init(rdists->id_bits);

        return 0;
}