/*
 * IOMMU API for ARM architected SMMU implementations.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) 2013 ARM Limited
 *
 * Author: Will Deacon <will.deacon@arm.com>
 *
 * This driver currently supports:
 *      - SMMUv1 and v2 implementations
 *      - Stream-matching and stream-indexing
 *      - v7/v8 long-descriptor format
 *      - Non-secure access to the SMMU
 *      - 4k and 64k pages, with contiguous pte hints.
 *      - Up to 39-bit addressing
 *      - Context fault reporting
 */

#define pr_fmt(fmt) "arm-smmu: " fmt

#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iommu.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include <linux/amba/bus.h>

#include <asm/pgalloc.h>

/* Maximum number of stream IDs assigned to a single device */
#define MAX_MASTER_STREAMIDS            8

/* Maximum number of context banks per SMMU */
#define ARM_SMMU_MAX_CBS                128

/* Maximum number of mapping groups per SMMU */
#define ARM_SMMU_MAX_SMRS               128

/* SMMU global address space */
#define ARM_SMMU_GR0(smmu)              ((smmu)->base)
#define ARM_SMMU_GR1(smmu)              ((smmu)->base + (smmu)->pagesize)

/* Page table bits */
#define ARM_SMMU_PTE_PAGE               (((pteval_t)3) << 0)
#define ARM_SMMU_PTE_CONT               (((pteval_t)1) << 52)
#define ARM_SMMU_PTE_AF                 (((pteval_t)1) << 10)
#define ARM_SMMU_PTE_SH_NS              (((pteval_t)0) << 8)
#define ARM_SMMU_PTE_SH_OS              (((pteval_t)2) << 8)
#define ARM_SMMU_PTE_SH_IS              (((pteval_t)3) << 8)

#if PAGE_SIZE == SZ_4K
#define ARM_SMMU_PTE_CONT_ENTRIES       16
#elif PAGE_SIZE == SZ_64K
#define ARM_SMMU_PTE_CONT_ENTRIES       32
#else
#define ARM_SMMU_PTE_CONT_ENTRIES       1
#endif

#define ARM_SMMU_PTE_CONT_SIZE          (PAGE_SIZE * ARM_SMMU_PTE_CONT_ENTRIES)
#define ARM_SMMU_PTE_CONT_MASK          (~(ARM_SMMU_PTE_CONT_SIZE - 1))
#define ARM_SMMU_PTE_HWTABLE_SIZE       (PTRS_PER_PTE * sizeof(pte_t))

/* Stage-1 PTE */
#define ARM_SMMU_PTE_AP_UNPRIV          (((pteval_t)1) << 6)
#define ARM_SMMU_PTE_AP_RDONLY          (((pteval_t)2) << 6)
#define ARM_SMMU_PTE_ATTRINDX_SHIFT     2
#define ARM_SMMU_PTE_nG                 (((pteval_t)1) << 11)

/* Stage-2 PTE */
#define ARM_SMMU_PTE_HAP_FAULT          (((pteval_t)0) << 6)
#define ARM_SMMU_PTE_HAP_READ           (((pteval_t)1) << 6)
#define ARM_SMMU_PTE_HAP_WRITE          (((pteval_t)2) << 6)
#define ARM_SMMU_PTE_MEMATTR_OIWB       (((pteval_t)0xf) << 2)
#define ARM_SMMU_PTE_MEMATTR_NC         (((pteval_t)0x5) << 2)
#define ARM_SMMU_PTE_MEMATTR_DEV        (((pteval_t)0x1) << 2)

/* Configuration registers */
#define ARM_SMMU_GR0_sCR0               0x0
#define sCR0_CLIENTPD                   (1 << 0)
#define sCR0_GFRE                       (1 << 1)
#define sCR0_GFIE                       (1 << 2)
#define sCR0_GCFGFRE                    (1 << 4)
#define sCR0_GCFGFIE                    (1 << 5)
#define sCR0_USFCFG                     (1 << 10)
#define sCR0_VMIDPNE                    (1 << 11)
#define sCR0_PTM                        (1 << 12)
#define sCR0_FB                         (1 << 13)
#define sCR0_BSU_SHIFT                  14
#define sCR0_BSU_MASK                   0x3

/* Identification registers */
#define ARM_SMMU_GR0_ID0                0x20
#define ARM_SMMU_GR0_ID1                0x24
#define ARM_SMMU_GR0_ID2                0x28
#define ARM_SMMU_GR0_ID3                0x2c
#define ARM_SMMU_GR0_ID4                0x30
#define ARM_SMMU_GR0_ID5                0x34
#define ARM_SMMU_GR0_ID6                0x38
#define ARM_SMMU_GR0_ID7                0x3c
#define ARM_SMMU_GR0_sGFSR              0x48
#define ARM_SMMU_GR0_sGFSYNR0           0x50
#define ARM_SMMU_GR0_sGFSYNR1           0x54
#define ARM_SMMU_GR0_sGFSYNR2           0x58
#define ARM_SMMU_GR0_PIDR0              0xfe0
#define ARM_SMMU_GR0_PIDR1              0xfe4
#define ARM_SMMU_GR0_PIDR2              0xfe8

#define ID0_S1TS                        (1 << 30)
#define ID0_S2TS                        (1 << 29)
#define ID0_NTS                         (1 << 28)
#define ID0_SMS                         (1 << 27)
#define ID0_PTFS_SHIFT                  24
#define ID0_PTFS_MASK                   0x2
#define ID0_PTFS_V8_ONLY                0x2
#define ID0_CTTW                        (1 << 14)
#define ID0_NUMIRPT_SHIFT               16
#define ID0_NUMIRPT_MASK                0xff
#define ID0_NUMSMRG_SHIFT               0
#define ID0_NUMSMRG_MASK                0xff

#define ID1_PAGESIZE                    (1 << 31)
#define ID1_NUMPAGENDXB_SHIFT           28
#define ID1_NUMPAGENDXB_MASK            7
#define ID1_NUMS2CB_SHIFT               16
#define ID1_NUMS2CB_MASK                0xff
#define ID1_NUMCB_SHIFT                 0
#define ID1_NUMCB_MASK                  0xff

#define ID2_OAS_SHIFT                   4
#define ID2_OAS_MASK                    0xf
#define ID2_IAS_SHIFT                   0
#define ID2_IAS_MASK                    0xf
#define ID2_UBS_SHIFT                   8
#define ID2_UBS_MASK                    0xf
#define ID2_PTFS_4K                     (1 << 12)
#define ID2_PTFS_16K                    (1 << 13)
#define ID2_PTFS_64K                    (1 << 14)

#define PIDR2_ARCH_SHIFT                4
#define PIDR2_ARCH_MASK                 0xf

/* Global TLB invalidation */
#define ARM_SMMU_GR0_STLBIALL           0x60
#define ARM_SMMU_GR0_TLBIVMID           0x64
#define ARM_SMMU_GR0_TLBIALLNSNH        0x68
#define ARM_SMMU_GR0_TLBIALLH           0x6c
#define ARM_SMMU_GR0_sTLBGSYNC          0x70
#define ARM_SMMU_GR0_sTLBGSTATUS        0x74
#define sTLBGSTATUS_GSACTIVE            (1 << 0)
#define TLB_LOOP_TIMEOUT                1000000 /* 1s! */

/* Stream mapping registers */
#define ARM_SMMU_GR0_SMR(n)             (0x800 + ((n) << 2))
#define SMR_VALID                       (1 << 31)
#define SMR_MASK_SHIFT                  16
#define SMR_MASK_MASK                   0x7fff
#define SMR_ID_SHIFT                    0
#define SMR_ID_MASK                     0x7fff

#define ARM_SMMU_GR0_S2CR(n)            (0xc00 + ((n) << 2))
#define S2CR_CBNDX_SHIFT                0
#define S2CR_CBNDX_MASK                 0xff
#define S2CR_TYPE_SHIFT                 16
#define S2CR_TYPE_MASK                  0x3
#define S2CR_TYPE_TRANS                 (0 << S2CR_TYPE_SHIFT)
#define S2CR_TYPE_BYPASS                (1 << S2CR_TYPE_SHIFT)
#define S2CR_TYPE_FAULT                 (2 << S2CR_TYPE_SHIFT)

/* Context bank attribute registers */
#define ARM_SMMU_GR1_CBAR(n)            (0x0 + ((n) << 2))
#define CBAR_VMID_SHIFT                 0
#define CBAR_VMID_MASK                  0xff
#define CBAR_S1_MEMATTR_SHIFT           12
#define CBAR_S1_MEMATTR_MASK            0xf
#define CBAR_S1_MEMATTR_WB              0xf
#define CBAR_TYPE_SHIFT                 16
#define CBAR_TYPE_MASK                  0x3
#define CBAR_TYPE_S2_TRANS              (0 << CBAR_TYPE_SHIFT)
#define CBAR_TYPE_S1_TRANS_S2_BYPASS    (1 << CBAR_TYPE_SHIFT)
#define CBAR_TYPE_S1_TRANS_S2_FAULT     (2 << CBAR_TYPE_SHIFT)
#define CBAR_TYPE_S1_TRANS_S2_TRANS     (3 << CBAR_TYPE_SHIFT)
#define CBAR_IRPTNDX_SHIFT              24
#define CBAR_IRPTNDX_MASK               0xff

#define ARM_SMMU_GR1_CBA2R(n)           (0x800 + ((n) << 2))
#define CBA2R_RW64_32BIT                (0 << 0)
#define CBA2R_RW64_64BIT                (1 << 0)

/* Translation context bank */
#define ARM_SMMU_CB_BASE(smmu)          ((smmu)->base + ((smmu)->size >> 1))
#define ARM_SMMU_CB(smmu, n)            ((n) * (smmu)->pagesize)

#define ARM_SMMU_CB_SCTLR               0x0
#define ARM_SMMU_CB_RESUME              0x8
#define ARM_SMMU_CB_TTBCR2              0x10
#define ARM_SMMU_CB_TTBR0_LO            0x20
#define ARM_SMMU_CB_TTBR0_HI            0x24
#define ARM_SMMU_CB_TTBCR               0x30
#define ARM_SMMU_CB_S1_MAIR0            0x38
#define ARM_SMMU_CB_FSR                 0x58
#define ARM_SMMU_CB_FAR_LO              0x60
#define ARM_SMMU_CB_FAR_HI              0x64
#define ARM_SMMU_CB_FSYNR0              0x68
#define ARM_SMMU_CB_S1_TLBIASID         0x610

#define SCTLR_S1_ASIDPNE                (1 << 12)
#define SCTLR_CFCFG                     (1 << 7)
#define SCTLR_CFIE                      (1 << 6)
#define SCTLR_CFRE                      (1 << 5)
#define SCTLR_E                         (1 << 4)
#define SCTLR_AFE                       (1 << 2)
#define SCTLR_TRE                       (1 << 1)
#define SCTLR_M                         (1 << 0)
#define SCTLR_EAE_SBOP                  (SCTLR_AFE | SCTLR_TRE)

#define RESUME_RETRY                    (0 << 0)
#define RESUME_TERMINATE                (1 << 0)

#define TTBCR_EAE                       (1 << 31)

#define TTBCR_PASIZE_SHIFT              16
#define TTBCR_PASIZE_MASK               0x7

#define TTBCR_TG0_4K                    (0 << 14)
#define TTBCR_TG0_64K                   (1 << 14)

#define TTBCR_SH0_SHIFT                 12
#define TTBCR_SH0_MASK                  0x3
#define TTBCR_SH_NS                     0
#define TTBCR_SH_OS                     2
#define TTBCR_SH_IS                     3

#define TTBCR_ORGN0_SHIFT               10
#define TTBCR_IRGN0_SHIFT               8
#define TTBCR_RGN_MASK                  0x3
#define TTBCR_RGN_NC                    0
#define TTBCR_RGN_WBWA                  1
#define TTBCR_RGN_WT                    2
#define TTBCR_RGN_WB                    3

#define TTBCR_SL0_SHIFT                 6
#define TTBCR_SL0_MASK                  0x3
#define TTBCR_SL0_LVL_2                 0
#define TTBCR_SL0_LVL_1                 1

#define TTBCR_T1SZ_SHIFT                16
#define TTBCR_T0SZ_SHIFT                0
#define TTBCR_SZ_MASK                   0xf

#define TTBCR2_SEP_SHIFT                15
#define TTBCR2_SEP_MASK                 0x7

#define TTBCR2_PASIZE_SHIFT             0
#define TTBCR2_PASIZE_MASK              0x7

/* Common definitions for PASize and SEP fields */
#define TTBCR2_ADDR_32                  0
#define TTBCR2_ADDR_36                  1
#define TTBCR2_ADDR_40                  2
#define TTBCR2_ADDR_42                  3
#define TTBCR2_ADDR_44                  4
#define TTBCR2_ADDR_48                  5

#define TTBRn_HI_ASID_SHIFT             16

#define MAIR_ATTR_SHIFT(n)              ((n) << 3)
#define MAIR_ATTR_MASK                  0xff
#define MAIR_ATTR_DEVICE                0x04
#define MAIR_ATTR_NC                    0x44
#define MAIR_ATTR_WBRWA                 0xff
#define MAIR_ATTR_IDX_NC                0
#define MAIR_ATTR_IDX_CACHE             1
#define MAIR_ATTR_IDX_DEV               2

#define FSR_MULTI                       (1 << 31)
#define FSR_SS                          (1 << 30)
#define FSR_UUT                         (1 << 8)
#define FSR_ASF                         (1 << 7)
#define FSR_TLBLKF                      (1 << 6)
#define FSR_TLBMCF                      (1 << 5)
#define FSR_EF                          (1 << 4)
#define FSR_PF                          (1 << 3)
#define FSR_AFF                         (1 << 2)
#define FSR_TF                          (1 << 1)

#define FSR_IGN                         (FSR_AFF | FSR_ASF | FSR_TLBMCF |       \
                                         FSR_TLBLKF)
#define FSR_FAULT                       (FSR_MULTI | FSR_SS | FSR_UUT |         \
                                         FSR_EF | FSR_PF | FSR_TF | FSR_IGN)

#define FSYNR0_WNR                      (1 << 4)

struct arm_smmu_smr {
        u8                              idx;
        u16                             mask;
        u16                             id;
};

struct arm_smmu_master {
        struct device_node              *of_node;

        /*
         * The following is specific to the master's position in the
         * SMMU chain.
         */
        struct rb_node                  node;
        int                             num_streamids;
        u16                             streamids[MAX_MASTER_STREAMIDS];

        /*
         * We only need to allocate these on the root SMMU, as we
         * configure unmatched streams to bypass translation.
         */
        struct arm_smmu_smr             *smrs;
};

struct arm_smmu_device {
        struct device                   *dev;
        struct device_node              *parent_of_node;

        void __iomem                    *base;
        unsigned long                   size;
        unsigned long                   pagesize;

#define ARM_SMMU_FEAT_COHERENT_WALK     (1 << 0)
#define ARM_SMMU_FEAT_STREAM_MATCH      (1 << 1)
#define ARM_SMMU_FEAT_TRANS_S1          (1 << 2)
#define ARM_SMMU_FEAT_TRANS_S2          (1 << 3)
#define ARM_SMMU_FEAT_TRANS_NESTED      (1 << 4)
        u32                             features;
        int                             version;

        u32                             num_context_banks;
        u32                             num_s2_context_banks;
        DECLARE_BITMAP(context_map, ARM_SMMU_MAX_CBS);
        atomic_t                        irptndx;

        u32                             num_mapping_groups;
        DECLARE_BITMAP(smr_map, ARM_SMMU_MAX_SMRS);

        unsigned long                   input_size;
        unsigned long                   s1_output_size;
        unsigned long                   s2_output_size;

        u32                             num_global_irqs;
        u32                             num_context_irqs;
        unsigned int                    *irqs;

        struct list_head                list;
        struct rb_root                  masters;
};

struct arm_smmu_cfg {
        struct arm_smmu_device          *smmu;
        u8                              cbndx;
        u8                              irptndx;
        u32                             cbar;
        pgd_t                           *pgd;
};
#define INVALID_IRPTNDX                 0xff

#define ARM_SMMU_CB_ASID(cfg)           ((cfg)->cbndx)
#define ARM_SMMU_CB_VMID(cfg)           ((cfg)->cbndx + 1)

struct arm_smmu_domain {
        /*
         * A domain can span across multiple, chained SMMUs and requires
         * all devices within the domain to follow the same translation
         * path.
         */
        struct arm_smmu_device          *leaf_smmu;
        struct arm_smmu_cfg             root_cfg;
        phys_addr_t                     output_mask;

        struct mutex                    lock;
};

static DEFINE_SPINLOCK(arm_smmu_devices_lock);
static LIST_HEAD(arm_smmu_devices);

static struct arm_smmu_master *find_smmu_master(struct arm_smmu_device *smmu,
                                                struct device_node *dev_node)
{
        struct rb_node *node = smmu->masters.rb_node;

        while (node) {
                struct arm_smmu_master *master;
                master = container_of(node, struct arm_smmu_master, node);

                if (dev_node < master->of_node)
                        node = node->rb_left;
                else if (dev_node > master->of_node)
                        node = node->rb_right;
                else
                        return master;
        }

        return NULL;
}

static int insert_smmu_master(struct arm_smmu_device *smmu,
                              struct arm_smmu_master *master)
{
        struct rb_node **new, *parent;

        new = &smmu->masters.rb_node;
        parent = NULL;
        while (*new) {
                struct arm_smmu_master *this;
                this = container_of(*new, struct arm_smmu_master, node);

                parent = *new;
                if (master->of_node < this->of_node)
                        new = &((*new)->rb_left);
                else if (master->of_node > this->of_node)
                        new = &((*new)->rb_right);
                else
                        return -EEXIST;
        }

        rb_link_node(&master->node, parent, new);
        rb_insert_color(&master->node, &smmu->masters);
        return 0;
}

static int register_smmu_master(struct arm_smmu_device *smmu,
                                struct device *dev,
                                struct of_phandle_args *masterspec)
{
        int i;
        struct arm_smmu_master *master;

        master = find_smmu_master(smmu, masterspec->np);
        if (master) {
                dev_err(dev,
                        "rejecting multiple registrations for master device %s\n",
                        masterspec->np->name);
                return -EBUSY;
        }

        if (masterspec->args_count > MAX_MASTER_STREAMIDS) {
                dev_err(dev,
                        "reached maximum number (%d) of stream IDs for master device %s\n",
                        MAX_MASTER_STREAMIDS, masterspec->np->name);
                return -ENOSPC;
        }

        master = devm_kzalloc(dev, sizeof(*master), GFP_KERNEL);
        if (!master)
                return -ENOMEM;

        master->of_node         = masterspec->np;
        master->num_streamids   = masterspec->args_count;

        for (i = 0; i < master->num_streamids; ++i)
                master->streamids[i] = masterspec->args[i];

        return insert_smmu_master(smmu, master);
}

static struct arm_smmu_device *find_parent_smmu(struct arm_smmu_device *smmu)
{
        struct arm_smmu_device *parent;

        if (!smmu->parent_of_node)
                return NULL;

        spin_lock(&arm_smmu_devices_lock);
        list_for_each_entry(parent, &arm_smmu_devices, list)
                if (parent->dev->of_node == smmu->parent_of_node)
                        goto out_unlock;

        parent = NULL;
        dev_warn(smmu->dev,
                 "Failed to find SMMU parent despite parent in DT\n");
out_unlock:
        spin_unlock(&arm_smmu_devices_lock);
        return parent;
}

static int __arm_smmu_alloc_bitmap(unsigned long *map, int start, int end)
{
        int idx;

        do {
                idx = find_next_zero_bit(map, end, start);
                if (idx == end)
                        return -ENOSPC;
        } while (test_and_set_bit(idx, map));

        return idx;
}

static void __arm_smmu_free_bitmap(unsigned long *map, int idx)
{
        clear_bit(idx, map);
}

/* Wait for any pending TLB invalidations to complete */
static void arm_smmu_tlb_sync(struct arm_smmu_device *smmu)
{
        int count = 0;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

        writel_relaxed(0, gr0_base + ARM_SMMU_GR0_sTLBGSYNC);
        while (readl_relaxed(gr0_base + ARM_SMMU_GR0_sTLBGSTATUS)
               & sTLBGSTATUS_GSACTIVE) {
                cpu_relax();
                if (++count == TLB_LOOP_TIMEOUT) {
                        dev_err_ratelimited(smmu->dev,
                        "TLB sync timed out -- SMMU may be deadlocked\n");
                        return;
                }
                udelay(1);
        }
}

static void arm_smmu_tlb_inv_context(struct arm_smmu_cfg *cfg)
{
        struct arm_smmu_device *smmu = cfg->smmu;
        void __iomem *base = ARM_SMMU_GR0(smmu);
        bool stage1 = cfg->cbar != CBAR_TYPE_S2_TRANS;

        if (stage1) {
                base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, cfg->cbndx);
                writel_relaxed(ARM_SMMU_CB_ASID(cfg),
                               base + ARM_SMMU_CB_S1_TLBIASID);
        } else {
                base = ARM_SMMU_GR0(smmu);
                writel_relaxed(ARM_SMMU_CB_VMID(cfg),
                               base + ARM_SMMU_GR0_TLBIVMID);
        }

        arm_smmu_tlb_sync(smmu);
}

static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
{
        int flags, ret;
        u32 fsr, far, fsynr, resume;
        unsigned long iova;
        struct iommu_domain *domain = dev;
        struct arm_smmu_domain *smmu_domain = domain->priv;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;
        struct arm_smmu_device *smmu = root_cfg->smmu;
        void __iomem *cb_base;

        cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, root_cfg->cbndx);
        fsr = readl_relaxed(cb_base + ARM_SMMU_CB_FSR);

        if (!(fsr & FSR_FAULT))
                return IRQ_NONE;

        if (fsr & FSR_IGN)
                dev_err_ratelimited(smmu->dev,
                                    "Unexpected context fault (fsr 0x%u)\n",
                                    fsr);

        fsynr = readl_relaxed(cb_base + ARM_SMMU_CB_FSYNR0);
        flags = fsynr & FSYNR0_WNR ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ;

        far = readl_relaxed(cb_base + ARM_SMMU_CB_FAR_LO);
        iova = far;
#ifdef CONFIG_64BIT
        far = readl_relaxed(cb_base + ARM_SMMU_CB_FAR_HI);
        iova |= ((unsigned long)far << 32);
#endif

        if (!report_iommu_fault(domain, smmu->dev, iova, flags)) {
                ret = IRQ_HANDLED;
                resume = RESUME_RETRY;
        } else {
                dev_err_ratelimited(smmu->dev,
                    "Unhandled context fault: iova=0x%08lx, fsynr=0x%x, cb=%d\n",
                    iova, fsynr, root_cfg->cbndx);
                ret = IRQ_NONE;
                resume = RESUME_TERMINATE;
        }

        /* Clear the faulting FSR */
        writel(fsr, cb_base + ARM_SMMU_CB_FSR);

        /* Retry or terminate any stalled transactions */
        if (fsr & FSR_SS)
                writel_relaxed(resume, cb_base + ARM_SMMU_CB_RESUME);

        return ret;
}

static irqreturn_t arm_smmu_global_fault(int irq, void *dev)
{
        u32 gfsr, gfsynr0, gfsynr1, gfsynr2;
        struct arm_smmu_device *smmu = dev;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

        gfsr = readl_relaxed(gr0_base + ARM_SMMU_GR0_sGFSR);
        if (!gfsr)
                return IRQ_NONE;

        gfsynr0 = readl_relaxed(gr0_base + ARM_SMMU_GR0_sGFSYNR0);
        gfsynr1 = readl_relaxed(gr0_base + ARM_SMMU_GR0_sGFSYNR1);
        gfsynr2 = readl_relaxed(gr0_base + ARM_SMMU_GR0_sGFSYNR2);

        dev_err_ratelimited(smmu->dev,
                "Unexpected global fault, this could be serious\n");
        dev_err_ratelimited(smmu->dev,
                "\tGFSR 0x%08x, GFSYNR0 0x%08x, GFSYNR1 0x%08x, GFSYNR2 0x%08x\n",
                gfsr, gfsynr0, gfsynr1, gfsynr2);

        writel(gfsr, gr0_base + ARM_SMMU_GR0_sGFSR);
        return IRQ_HANDLED;
}

static void arm_smmu_init_context_bank(struct arm_smmu_domain *smmu_domain)
{
        u32 reg;
        bool stage1;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;
        struct arm_smmu_device *smmu = root_cfg->smmu;
        void __iomem *cb_base, *gr0_base, *gr1_base;

        gr0_base = ARM_SMMU_GR0(smmu);
        gr1_base = ARM_SMMU_GR1(smmu);
        stage1 = root_cfg->cbar != CBAR_TYPE_S2_TRANS;
        cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, root_cfg->cbndx);

        /* CBAR */
        reg = root_cfg->cbar;
        if (smmu->version == 1)
              reg |= root_cfg->irptndx << CBAR_IRPTNDX_SHIFT;

        /* Use the weakest memory type, so it is overridden by the pte */
        if (stage1)
                reg |= (CBAR_S1_MEMATTR_WB << CBAR_S1_MEMATTR_SHIFT);
        else
                reg |= ARM_SMMU_CB_VMID(root_cfg) << CBAR_VMID_SHIFT;
        writel_relaxed(reg, gr1_base + ARM_SMMU_GR1_CBAR(root_cfg->cbndx));

        if (smmu->version > 1) {
                /* CBA2R */
#ifdef CONFIG_64BIT
                reg = CBA2R_RW64_64BIT;
#else
                reg = CBA2R_RW64_32BIT;
#endif
                writel_relaxed(reg,
                               gr1_base + ARM_SMMU_GR1_CBA2R(root_cfg->cbndx));

                /* TTBCR2 */
                switch (smmu->input_size) {
                case 32:
                        reg = (TTBCR2_ADDR_32 << TTBCR2_SEP_SHIFT);
                        break;
                case 36:
                        reg = (TTBCR2_ADDR_36 << TTBCR2_SEP_SHIFT);
                        break;
                case 39:
                        reg = (TTBCR2_ADDR_40 << TTBCR2_SEP_SHIFT);
                        break;
                case 42:
                        reg = (TTBCR2_ADDR_42 << TTBCR2_SEP_SHIFT);
                        break;
                case 44:
                        reg = (TTBCR2_ADDR_44 << TTBCR2_SEP_SHIFT);
                        break;
                case 48:
                        reg = (TTBCR2_ADDR_48 << TTBCR2_SEP_SHIFT);
                        break;
                }

                switch (smmu->s1_output_size) {
                case 32:
                        reg |= (TTBCR2_ADDR_32 << TTBCR2_PASIZE_SHIFT);
                        break;
                case 36:
                        reg |= (TTBCR2_ADDR_36 << TTBCR2_PASIZE_SHIFT);
                        break;
                case 39:
                        reg |= (TTBCR2_ADDR_40 << TTBCR2_PASIZE_SHIFT);
                        break;
                case 42:
                        reg |= (TTBCR2_ADDR_42 << TTBCR2_PASIZE_SHIFT);
                        break;
                case 44:
                        reg |= (TTBCR2_ADDR_44 << TTBCR2_PASIZE_SHIFT);
                        break;
                case 48:
                        reg |= (TTBCR2_ADDR_48 << TTBCR2_PASIZE_SHIFT);
                        break;
                }

                if (stage1)
                        writel_relaxed(reg, cb_base + ARM_SMMU_CB_TTBCR2);
        }

        /* TTBR0 */
        reg = __pa(root_cfg->pgd);
        writel_relaxed(reg, cb_base + ARM_SMMU_CB_TTBR0_LO);
        reg = (phys_addr_t)__pa(root_cfg->pgd) >> 32;
        if (stage1)
                reg |= ARM_SMMU_CB_ASID(root_cfg) << TTBRn_HI_ASID_SHIFT;
        writel_relaxed(reg, cb_base + ARM_SMMU_CB_TTBR0_HI);

        /*
         * TTBCR
         * We use long descriptor, with inner-shareable WBWA tables in TTBR0.
         */
        if (smmu->version > 1) {
                if (PAGE_SIZE == SZ_4K)
                        reg = TTBCR_TG0_4K;
                else
                        reg = TTBCR_TG0_64K;

                if (!stage1) {
                        switch (smmu->s2_output_size) {
                        case 32:
                                reg |= (TTBCR2_ADDR_32 << TTBCR_PASIZE_SHIFT);
                                break;
                        case 36:
                                reg |= (TTBCR2_ADDR_36 << TTBCR_PASIZE_SHIFT);
                                break;
                        case 40:
                                reg |= (TTBCR2_ADDR_40 << TTBCR_PASIZE_SHIFT);
                                break;
                        case 42:
                                reg |= (TTBCR2_ADDR_42 << TTBCR_PASIZE_SHIFT);
                                break;
                        case 44:
                                reg |= (TTBCR2_ADDR_44 << TTBCR_PASIZE_SHIFT);
                                break;
                        case 48:
                                reg |= (TTBCR2_ADDR_48 << TTBCR_PASIZE_SHIFT);
                                break;
                        }
                } else {
                        reg |= (64 - smmu->s1_output_size) << TTBCR_T0SZ_SHIFT;
                }
        } else {
                reg = 0;
        }

        reg |= TTBCR_EAE |
              (TTBCR_SH_IS << TTBCR_SH0_SHIFT) |
              (TTBCR_RGN_WBWA << TTBCR_ORGN0_SHIFT) |
              (TTBCR_RGN_WBWA << TTBCR_IRGN0_SHIFT) |
              (TTBCR_SL0_LVL_1 << TTBCR_SL0_SHIFT);
        writel_relaxed(reg, cb_base + ARM_SMMU_CB_TTBCR);

        /* MAIR0 (stage-1 only) */
        if (stage1) {
                reg = (MAIR_ATTR_NC << MAIR_ATTR_SHIFT(MAIR_ATTR_IDX_NC)) |
                      (MAIR_ATTR_WBRWA << MAIR_ATTR_SHIFT(MAIR_ATTR_IDX_CACHE)) |
                      (MAIR_ATTR_DEVICE << MAIR_ATTR_SHIFT(MAIR_ATTR_IDX_DEV));
                writel_relaxed(reg, cb_base + ARM_SMMU_CB_S1_MAIR0);
        }

        /* SCTLR */
        reg = SCTLR_CFCFG | SCTLR_CFIE | SCTLR_CFRE | SCTLR_M | SCTLR_EAE_SBOP;
        if (stage1)
                reg |= SCTLR_S1_ASIDPNE;
#ifdef __BIG_ENDIAN
        reg |= SCTLR_E;
#endif
        writel_relaxed(reg, cb_base + ARM_SMMU_CB_SCTLR);
}

static int arm_smmu_init_domain_context(struct iommu_domain *domain,
                                        struct device *dev)
{
        int irq, ret, start;
        struct arm_smmu_domain *smmu_domain = domain->priv;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;
        struct arm_smmu_device *smmu, *parent;

        /*
         * Walk the SMMU chain to find the root device for this chain.
         * We assume that no masters have translations which terminate
         * early, and therefore check that the root SMMU does indeed have
         * a StreamID for the master in question.
         */
        parent = dev->archdata.iommu;
        smmu_domain->output_mask = -1;
        do {
                smmu = parent;
                smmu_domain->output_mask &= (1ULL << smmu->s2_output_size) - 1;
        } while ((parent = find_parent_smmu(smmu)));

        if (!find_smmu_master(smmu, dev->of_node)) {
                dev_err(dev, "unable to find root SMMU for device\n");
                return -ENODEV;
        }

        if (smmu->features & ARM_SMMU_FEAT_TRANS_NESTED) {
                /*
                 * We will likely want to change this if/when KVM gets
                 * involved.
                 */
                root_cfg->cbar = CBAR_TYPE_S1_TRANS_S2_BYPASS;
                start = smmu->num_s2_context_banks;
        } else if (smmu->features & ARM_SMMU_FEAT_TRANS_S2) {
                root_cfg->cbar = CBAR_TYPE_S2_TRANS;
                start = 0;
        } else {
                root_cfg->cbar = CBAR_TYPE_S1_TRANS_S2_BYPASS;
                start = smmu->num_s2_context_banks;
        }

        ret = __arm_smmu_alloc_bitmap(smmu->context_map, start,
                                      smmu->num_context_banks);
        if (IS_ERR_VALUE(ret))
                return ret;

        root_cfg->cbndx = ret;
        if (smmu->version == 1) {
                root_cfg->irptndx = atomic_inc_return(&smmu->irptndx);
                root_cfg->irptndx %= smmu->num_context_irqs;
        } else {
                root_cfg->irptndx = root_cfg->cbndx;
        }

        irq = smmu->irqs[smmu->num_global_irqs + root_cfg->irptndx];
        ret = request_irq(irq, arm_smmu_context_fault, IRQF_SHARED,
                          "arm-smmu-context-fault", domain);
        if (IS_ERR_VALUE(ret)) {
                dev_err(smmu->dev, "failed to request context IRQ %d (%u)\n",
                        root_cfg->irptndx, irq);
                root_cfg->irptndx = INVALID_IRPTNDX;
                goto out_free_context;
        }

        root_cfg->smmu = smmu;
        arm_smmu_init_context_bank(smmu_domain);
        return ret;

out_free_context:
        __arm_smmu_free_bitmap(smmu->context_map, root_cfg->cbndx);
        return ret;
}

static void arm_smmu_destroy_domain_context(struct iommu_domain *domain)
{
        struct arm_smmu_domain *smmu_domain = domain->priv;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;
        struct arm_smmu_device *smmu = root_cfg->smmu;
        void __iomem *cb_base;
        int irq;

        if (!smmu)
                return;

        /* Disable the context bank and nuke the TLB before freeing it. */
        cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, root_cfg->cbndx);
        writel_relaxed(0, cb_base + ARM_SMMU_CB_SCTLR);
        arm_smmu_tlb_inv_context(root_cfg);

        if (root_cfg->irptndx != INVALID_IRPTNDX) {
                irq = smmu->irqs[smmu->num_global_irqs + root_cfg->irptndx];
                free_irq(irq, domain);
        }

        __arm_smmu_free_bitmap(smmu->context_map, root_cfg->cbndx);
}

static int arm_smmu_domain_init(struct iommu_domain *domain)
{
        struct arm_smmu_domain *smmu_domain;
        pgd_t *pgd;

        /*
         * Allocate the domain and initialise some of its data structures.
         * We can't really do anything meaningful until we've added a
         * master.
         */
        smmu_domain = kzalloc(sizeof(*smmu_domain), GFP_KERNEL);
        if (!smmu_domain)
                return -ENOMEM;

        pgd = kzalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL);
        if (!pgd)
                goto out_free_domain;
        smmu_domain->root_cfg.pgd = pgd;

        mutex_init(&smmu_domain->lock);
        domain->priv = smmu_domain;
        return 0;

out_free_domain:
        kfree(smmu_domain);
        return -ENOMEM;
}

static void arm_smmu_free_ptes(pmd_t *pmd)
{
        pgtable_t table = pmd_pgtable(*pmd);
        pgtable_page_dtor(table);
        __free_page(table);
}

static void arm_smmu_free_pmds(pud_t *pud)
{
        int i;
        pmd_t *pmd, *pmd_base = pmd_offset(pud, 0);

        pmd = pmd_base;
        for (i = 0; i < PTRS_PER_PMD; ++i) {
                if (pmd_none(*pmd))
                        continue;

                arm_smmu_free_ptes(pmd);
                pmd++;
        }

        pmd_free(NULL, pmd_base);
}

static void arm_smmu_free_puds(pgd_t *pgd)
{
        int i;
        pud_t *pud, *pud_base = pud_offset(pgd, 0);

        pud = pud_base;
        for (i = 0; i < PTRS_PER_PUD; ++i) {
                if (pud_none(*pud))
                        continue;

                arm_smmu_free_pmds(pud);
                pud++;
        }

        pud_free(NULL, pud_base);
}

static void arm_smmu_free_pgtables(struct arm_smmu_domain *smmu_domain)
{
        int i;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;
        pgd_t *pgd, *pgd_base = root_cfg->pgd;

        /*
         * Recursively free the page tables for this domain. We don't
         * care about speculative TLB filling, because the TLB will be
         * nuked next time this context bank is re-allocated and no devices
         * currently map to these tables.
         */
        pgd = pgd_base;
        for (i = 0; i < PTRS_PER_PGD; ++i) {
                if (pgd_none(*pgd))
                        continue;
                arm_smmu_free_puds(pgd);
                pgd++;
        }

        kfree(pgd_base);
}

static void arm_smmu_domain_destroy(struct iommu_domain *domain)
{
        struct arm_smmu_domain *smmu_domain = domain->priv;

        /*
         * Free the domain resources. We assume that all devices have
         * already been detached.
         */
        arm_smmu_destroy_domain_context(domain);
        arm_smmu_free_pgtables(smmu_domain);
        kfree(smmu_domain);
}

static int arm_smmu_master_configure_smrs(struct arm_smmu_device *smmu,
                                          struct arm_smmu_master *master)
{
        int i;
        struct arm_smmu_smr *smrs;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

        if (!(smmu->features & ARM_SMMU_FEAT_STREAM_MATCH))
                return 0;

        if (master->smrs)
                return -EEXIST;

        smrs = kmalloc(sizeof(*smrs) * master->num_streamids, GFP_KERNEL);
        if (!smrs) {
                dev_err(smmu->dev, "failed to allocate %d SMRs for master %s\n",
                        master->num_streamids, master->of_node->name);
                return -ENOMEM;
        }

        /* Allocate the SMRs on the root SMMU */
        for (i = 0; i < master->num_streamids; ++i) {
                int idx = __arm_smmu_alloc_bitmap(smmu->smr_map, 0,
                                                  smmu->num_mapping_groups);
                if (IS_ERR_VALUE(idx)) {
                        dev_err(smmu->dev, "failed to allocate free SMR\n");
                        goto err_free_smrs;
                }

                smrs[i] = (struct arm_smmu_smr) {
                        .idx    = idx,
                        .mask   = 0, /* We don't currently share SMRs */
                        .id     = master->streamids[i],
                };
        }

        /* It worked! Now, poke the actual hardware */
        for (i = 0; i < master->num_streamids; ++i) {
                u32 reg = SMR_VALID | smrs[i].id << SMR_ID_SHIFT |
                          smrs[i].mask << SMR_MASK_SHIFT;
                writel_relaxed(reg, gr0_base + ARM_SMMU_GR0_SMR(smrs[i].idx));
        }

        master->smrs = smrs;
        return 0;

err_free_smrs:
        while (--i >= 0)
                __arm_smmu_free_bitmap(smmu->smr_map, smrs[i].idx);
        kfree(smrs);
        return -ENOSPC;
}

static void arm_smmu_master_free_smrs(struct arm_smmu_device *smmu,
                                      struct arm_smmu_master *master)
{
        int i;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
        struct arm_smmu_smr *smrs = master->smrs;

        /* Invalidate the SMRs before freeing back to the allocator */
        for (i = 0; i < master->num_streamids; ++i) {
                u8 idx = smrs[i].idx;
                writel_relaxed(~SMR_VALID, gr0_base + ARM_SMMU_GR0_SMR(idx));
                __arm_smmu_free_bitmap(smmu->smr_map, idx);
        }

        master->smrs = NULL;
        kfree(smrs);
}

static void arm_smmu_bypass_stream_mapping(struct arm_smmu_device *smmu,
                                           struct arm_smmu_master *master)
{
        int i;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

        for (i = 0; i < master->num_streamids; ++i) {
                u16 sid = master->streamids[i];
                writel_relaxed(S2CR_TYPE_BYPASS,
                               gr0_base + ARM_SMMU_GR0_S2CR(sid));
        }
}

static int arm_smmu_domain_add_master(struct arm_smmu_domain *smmu_domain,
                                      struct arm_smmu_master *master)
{
        int i, ret;
        struct arm_smmu_device *parent, *smmu = smmu_domain->root_cfg.smmu;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);

        ret = arm_smmu_master_configure_smrs(smmu, master);
        if (ret)
                return ret;

        /* Bypass the leaves */
        smmu = smmu_domain->leaf_smmu;
        while ((parent = find_parent_smmu(smmu))) {
                /*
                 * We won't have a StreamID match for anything but the root
                 * smmu, so we only need to worry about StreamID indexing,
                 * where we must install bypass entries in the S2CRs.
                 */
                if (smmu->features & ARM_SMMU_FEAT_STREAM_MATCH)
                        continue;

                arm_smmu_bypass_stream_mapping(smmu, master);
                smmu = parent;
        }

        /* Now we're at the root, time to point at our context bank */
        for (i = 0; i < master->num_streamids; ++i) {
                u32 idx, s2cr;
                idx = master->smrs ? master->smrs[i].idx : master->streamids[i];
                s2cr = (S2CR_TYPE_TRANS << S2CR_TYPE_SHIFT) |
                       (smmu_domain->root_cfg.cbndx << S2CR_CBNDX_SHIFT);
                writel_relaxed(s2cr, gr0_base + ARM_SMMU_GR0_S2CR(idx));
        }

        return 0;
}

static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
                                          struct arm_smmu_master *master)
{
        struct arm_smmu_device *smmu = smmu_domain->root_cfg.smmu;

        /*
         * We *must* clear the S2CR first, because freeing the SMR means
         * that it can be re-allocated immediately.
         */
        arm_smmu_bypass_stream_mapping(smmu, master);
        arm_smmu_master_free_smrs(smmu, master);
}

static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
{
        int ret = -EINVAL;
        struct arm_smmu_domain *smmu_domain = domain->priv;
        struct arm_smmu_device *device_smmu = dev->archdata.iommu;
        struct arm_smmu_master *master;

        if (!device_smmu) {
                dev_err(dev, "cannot attach to SMMU, is it on the same bus?\n");
                return -ENXIO;
        }

        /*
         * Sanity check the domain. We don't currently support domains
         * that cross between different SMMU chains.
         */
        mutex_lock(&smmu_domain->lock);
        if (!smmu_domain->leaf_smmu) {
                /* Now that we have a master, we can finalise the domain */
                ret = arm_smmu_init_domain_context(domain, dev);
                if (IS_ERR_VALUE(ret))
                        goto err_unlock;

                smmu_domain->leaf_smmu = device_smmu;
        } else if (smmu_domain->leaf_smmu != device_smmu) {
                dev_err(dev,
                        "cannot attach to SMMU %s whilst already attached to domain on SMMU %s\n",
                        dev_name(smmu_domain->leaf_smmu->dev),
                        dev_name(device_smmu->dev));
                goto err_unlock;
        }
        mutex_unlock(&smmu_domain->lock);

        /* Looks ok, so add the device to the domain */
        master = find_smmu_master(smmu_domain->leaf_smmu, dev->of_node);
        if (!master)
                return -ENODEV;

        return arm_smmu_domain_add_master(smmu_domain, master);

err_unlock:
        mutex_unlock(&smmu_domain->lock);
        return ret;
}

static void arm_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
{
        struct arm_smmu_domain *smmu_domain = domain->priv;
        struct arm_smmu_master *master;

        master = find_smmu_master(smmu_domain->leaf_smmu, dev->of_node);
        if (master)
                arm_smmu_domain_remove_master(smmu_domain, master);
}

static void arm_smmu_flush_pgtable(struct arm_smmu_device *smmu, void *addr,
                                   size_t size)
{
        unsigned long offset = (unsigned long)addr & ~PAGE_MASK;

        /*
         * If the SMMU can't walk tables in the CPU caches, treat them
         * like non-coherent DMA since we need to flush the new entries
         * all the way out to memory. There's no possibility of recursion
         * here as the SMMU table walker will not be wired through another
         * SMMU.
         */
        if (!(smmu->features & ARM_SMMU_FEAT_COHERENT_WALK))
                dma_map_page(smmu->dev, virt_to_page(addr), offset, size,
                             DMA_TO_DEVICE);
}

static bool arm_smmu_pte_is_contiguous_range(unsigned long addr,
                                             unsigned long end)
{
        return !(addr & ~ARM_SMMU_PTE_CONT_MASK) &&
                (addr + ARM_SMMU_PTE_CONT_SIZE <= end);
}

static int arm_smmu_alloc_init_pte(struct arm_smmu_device *smmu, pmd_t *pmd,
                                   unsigned long addr, unsigned long end,
                                   unsigned long pfn, int flags, int stage)
{
        pte_t *pte, *start;
        pteval_t pteval = ARM_SMMU_PTE_PAGE | ARM_SMMU_PTE_AF;

        if (pmd_none(*pmd)) {
                /* Allocate a new set of tables */
                pgtable_t table = alloc_page(PGALLOC_GFP);
                if (!table)
                        return -ENOMEM;

                arm_smmu_flush_pgtable(smmu, page_address(table),
                                       ARM_SMMU_PTE_HWTABLE_SIZE);
                if (!pgtable_page_ctor(table)) {
                        __free_page(table);
                        return -ENOMEM;
                }
                pmd_populate(NULL, pmd, table);
                arm_smmu_flush_pgtable(smmu, pmd, sizeof(*pmd));
        }

        if (stage == 1) {
                pteval |= ARM_SMMU_PTE_AP_UNPRIV | ARM_SMMU_PTE_nG;
                if (!(flags & IOMMU_WRITE) && (flags & IOMMU_READ))
                        pteval |= ARM_SMMU_PTE_AP_RDONLY;

                if (flags & IOMMU_CACHE)
                        pteval |= (MAIR_ATTR_IDX_CACHE <<
                                   ARM_SMMU_PTE_ATTRINDX_SHIFT);
        } else {
                pteval |= ARM_SMMU_PTE_HAP_FAULT;
                if (flags & IOMMU_READ)
                        pteval |= ARM_SMMU_PTE_HAP_READ;
                if (flags & IOMMU_WRITE)
                        pteval |= ARM_SMMU_PTE_HAP_WRITE;
                if (flags & IOMMU_CACHE)
                        pteval |= ARM_SMMU_PTE_MEMATTR_OIWB;
                else
                        pteval |= ARM_SMMU_PTE_MEMATTR_NC;
        }

        /* If no access, create a faulting entry to avoid TLB fills */
        if (!(flags & (IOMMU_READ | IOMMU_WRITE)))
                pteval &= ~ARM_SMMU_PTE_PAGE;

        pteval |= ARM_SMMU_PTE_SH_IS;
        start = pmd_page_vaddr(*pmd) + pte_index(addr);
        pte = start;

        /*
         * Install the page table entries. This is fairly complicated
         * since we attempt to make use of the contiguous hint in the
         * ptes where possible. The contiguous hint indicates a series
         * of ARM_SMMU_PTE_CONT_ENTRIES ptes mapping a physically
         * contiguous region with the following constraints:
         *
         *   - The region start is aligned to ARM_SMMU_PTE_CONT_SIZE
         *   - Each pte in the region has the contiguous hint bit set
         *
         * This complicates unmapping (also handled by this code, when
         * neither IOMMU_READ or IOMMU_WRITE are set) because it is
         * possible, yet highly unlikely, that a client may unmap only
         * part of a contiguous range. This requires clearing of the
         * contiguous hint bits in the range before installing the new
         * faulting entries.
         *
         * Note that re-mapping an address range without first unmapping
         * it is not supported, so TLB invalidation is not required here
         * and is instead performed at unmap and domain-init time.
         */
        do {
                int i = 1;
                pteval &= ~ARM_SMMU_PTE_CONT;

                if (arm_smmu_pte_is_contiguous_range(addr, end)) {
                        i = ARM_SMMU_PTE_CONT_ENTRIES;
                        pteval |= ARM_SMMU_PTE_CONT;
                } else if (pte_val(*pte) &
                           (ARM_SMMU_PTE_CONT | ARM_SMMU_PTE_PAGE)) {
                        int j;
                        pte_t *cont_start;
                        unsigned long idx = pte_index(addr);

                        idx &= ~(ARM_SMMU_PTE_CONT_ENTRIES - 1);
                        cont_start = pmd_page_vaddr(*pmd) + idx;
                        for (j = 0; j < ARM_SMMU_PTE_CONT_ENTRIES; ++j)
                                pte_val(*(cont_start + j)) &= ~ARM_SMMU_PTE_CONT;

                        arm_smmu_flush_pgtable(smmu, cont_start,
                                               sizeof(*pte) *
                                               ARM_SMMU_PTE_CONT_ENTRIES);
                }

                do {
                        *pte = pfn_pte(pfn, __pgprot(pteval));
                } while (pte++, pfn++, addr += PAGE_SIZE, --i);
        } while (addr != end);

        arm_smmu_flush_pgtable(smmu, start, sizeof(*pte) * (pte - start));
        return 0;
}

static int arm_smmu_alloc_init_pmd(struct arm_smmu_device *smmu, pud_t *pud,
                                   unsigned long addr, unsigned long end,
                                   phys_addr_t phys, int flags, int stage)
{
        int ret;
        pmd_t *pmd;
        unsigned long next, pfn = __phys_to_pfn(phys);

#ifndef __PAGETABLE_PMD_FOLDED
        if (pud_none(*pud)) {
                pmd = pmd_alloc_one(NULL, addr);
                if (!pmd)
                        return -ENOMEM;
        } else
#endif
                pmd = pmd_offset(pud, addr);

        do {
                next = pmd_addr_end(addr, end);
                ret = arm_smmu_alloc_init_pte(smmu, pmd, addr, end, pfn,
                                              flags, stage);
                pud_populate(NULL, pud, pmd);
                arm_smmu_flush_pgtable(smmu, pud, sizeof(*pud));
                phys += next - addr;
        } while (pmd++, addr = next, addr < end);

        return ret;
}

static int arm_smmu_alloc_init_pud(struct arm_smmu_device *smmu, pgd_t *pgd,
                                   unsigned long addr, unsigned long end,
                                   phys_addr_t phys, int flags, int stage)
{
        int ret = 0;
        pud_t *pud;
        unsigned long next;

#ifndef __PAGETABLE_PUD_FOLDED
        if (pgd_none(*pgd)) {
                pud = pud_alloc_one(NULL, addr);
                if (!pud)
                        return -ENOMEM;
        } else
#endif
                pud = pud_offset(pgd, addr);

        do {
                next = pud_addr_end(addr, end);
                ret = arm_smmu_alloc_init_pmd(smmu, pud, addr, next, phys,
                                              flags, stage);
                pgd_populate(NULL, pud, pgd);
                arm_smmu_flush_pgtable(smmu, pgd, sizeof(*pgd));
                phys += next - addr;
        } while (pud++, addr = next, addr < end);

        return ret;
}

static int arm_smmu_handle_mapping(struct arm_smmu_domain *smmu_domain,
                                   unsigned long iova, phys_addr_t paddr,
                                   size_t size, int flags)
{
        int ret, stage;
        unsigned long end;
        phys_addr_t input_mask, output_mask;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;
        pgd_t *pgd = root_cfg->pgd;
        struct arm_smmu_device *smmu = root_cfg->smmu;

        if (root_cfg->cbar == CBAR_TYPE_S2_TRANS) {
                stage = 2;
                output_mask = (1ULL << smmu->s2_output_size) - 1;
        } else {
                stage = 1;
                output_mask = (1ULL << smmu->s1_output_size) - 1;
        }

        if (!pgd)
                return -EINVAL;

        if (size & ~PAGE_MASK)
                return -EINVAL;

        input_mask = (1ULL << smmu->input_size) - 1;
        if ((phys_addr_t)iova & ~input_mask)
                return -ERANGE;

        if (paddr & ~output_mask)
                return -ERANGE;

        mutex_lock(&smmu_domain->lock);
        pgd += pgd_index(iova);
        end = iova + size;
        do {
                unsigned long next = pgd_addr_end(iova, end);

                ret = arm_smmu_alloc_init_pud(smmu, pgd, iova, next, paddr,
                                              flags, stage);
                if (ret)
                        goto out_unlock;

                paddr += next - iova;
                iova = next;
        } while (pgd++, iova != end);

out_unlock:
        mutex_unlock(&smmu_domain->lock);

        /* Ensure new page tables are visible to the hardware walker */
        if (smmu->features & ARM_SMMU_FEAT_COHERENT_WALK)
                dsb();

        return ret;
}

static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova,
                        phys_addr_t paddr, size_t size, int flags)
{
        struct arm_smmu_domain *smmu_domain = domain->priv;

        if (!smmu_domain)
                return -ENODEV;

        /* Check for silent address truncation up the SMMU chain. */
        if ((phys_addr_t)iova & ~smmu_domain->output_mask)
                return -ERANGE;

        return arm_smmu_handle_mapping(smmu_domain, iova, paddr, size, flags);
}

static size_t arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
                             size_t size)
{
        int ret;
        struct arm_smmu_domain *smmu_domain = domain->priv;

        ret = arm_smmu_handle_mapping(smmu_domain, iova, 0, size, 0);
        arm_smmu_tlb_inv_context(&smmu_domain->root_cfg);
        return ret ? ret : size;
}

static phys_addr_t arm_smmu_iova_to_phys(struct iommu_domain *domain,
                                         dma_addr_t iova)
{
        pgd_t *pgdp, pgd;
        pud_t pud;
        pmd_t pmd;
        pte_t pte;
        struct arm_smmu_domain *smmu_domain = domain->priv;
        struct arm_smmu_cfg *root_cfg = &smmu_domain->root_cfg;

        pgdp = root_cfg->pgd;
        if (!pgdp)
                return 0;

        pgd = *(pgdp + pgd_index(iova));
        if (pgd_none(pgd))
                return 0;

        pud = *pud_offset(&pgd, iova);
        if (pud_none(pud))
                return 0;

        pmd = *pmd_offset(&pud, iova);
        if (pmd_none(pmd))
                return 0;

        pte = *(pmd_page_vaddr(pmd) + pte_index(iova));
        if (pte_none(pte))
                return 0;

        return __pfn_to_phys(pte_pfn(pte)) | (iova & ~PAGE_MASK);
}

static int arm_smmu_domain_has_cap(struct iommu_domain *domain,
                                   unsigned long cap)
{
        unsigned long caps = 0;
        struct arm_smmu_domain *smmu_domain = domain->priv;

        if (smmu_domain->root_cfg.smmu->features & ARM_SMMU_FEAT_COHERENT_WALK)
                caps |= IOMMU_CAP_CACHE_COHERENCY;

        return !!(cap & caps);
}

static int arm_smmu_add_device(struct device *dev)
{
        struct arm_smmu_device *child, *parent, *smmu;
        struct arm_smmu_master *master = NULL;

        spin_lock(&arm_smmu_devices_lock);
        list_for_each_entry(parent, &arm_smmu_devices, list) {
                smmu = parent;

                /* Try to find a child of the current SMMU. */
                list_for_each_entry(child, &arm_smmu_devices, list) {
                        if (child->parent_of_node == parent->dev->of_node) {
                                /* Does the child sit above our master? */
                                master = find_smmu_master(child, dev->of_node);
                                if (master) {
                                        smmu = NULL;
                                        break;
                                }
                        }
                }

                /* We found some children, so keep searching. */
                if (!smmu) {
                        master = NULL;
                        continue;
                }

                master = find_smmu_master(smmu, dev->of_node);
                if (master)
                        break;
        }
        spin_unlock(&arm_smmu_devices_lock);

        if (!master)
                return -ENODEV;

        dev->archdata.iommu = smmu;
        return 0;
}

static void arm_smmu_remove_device(struct device *dev)
{
        dev->archdata.iommu = NULL;
}

static struct iommu_ops arm_smmu_ops = {
        .domain_init    = arm_smmu_domain_init,
        .domain_destroy = arm_smmu_domain_destroy,
        .attach_dev     = arm_smmu_attach_dev,
        .detach_dev     = arm_smmu_detach_dev,
        .map            = arm_smmu_map,
        .unmap          = arm_smmu_unmap,
        .iova_to_phys   = arm_smmu_iova_to_phys,
        .domain_has_cap = arm_smmu_domain_has_cap,
        .add_device     = arm_smmu_add_device,
        .remove_device  = arm_smmu_remove_device,
        .pgsize_bitmap  = (SECTION_SIZE |
                           ARM_SMMU_PTE_CONT_SIZE |
                           PAGE_SIZE),
};

static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
{
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
        void __iomem *cb_base;
        int i = 0;
        u32 reg;

        /* Clear Global FSR */
        reg = readl_relaxed(gr0_base + ARM_SMMU_GR0_sGFSR);
        writel(reg, gr0_base + ARM_SMMU_GR0_sGFSR);

        /* Mark all SMRn as invalid and all S2CRn as bypass */
        for (i = 0; i < smmu->num_mapping_groups; ++i) {
                writel_relaxed(~SMR_VALID, gr0_base + ARM_SMMU_GR0_SMR(i));
                writel_relaxed(S2CR_TYPE_BYPASS, gr0_base + ARM_SMMU_GR0_S2CR(i));
        }

        /* Make sure all context banks are disabled and clear CB_FSR  */
        for (i = 0; i < smmu->num_context_banks; ++i) {
                cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, i);
                writel_relaxed(0, cb_base + ARM_SMMU_CB_SCTLR);
                writel_relaxed(FSR_FAULT, cb_base + ARM_SMMU_CB_FSR);
        }

        /* Invalidate the TLB, just in case */
        writel_relaxed(0, gr0_base + ARM_SMMU_GR0_STLBIALL);
        writel_relaxed(0, gr0_base + ARM_SMMU_GR0_TLBIALLH);
        writel_relaxed(0, gr0_base + ARM_SMMU_GR0_TLBIALLNSNH);

        reg = readl_relaxed(gr0_base + ARM_SMMU_GR0_sCR0);

        /* Enable fault reporting */
        reg |= (sCR0_GFRE | sCR0_GFIE | sCR0_GCFGFRE | sCR0_GCFGFIE);

        /* Disable TLB broadcasting. */
        reg |= (sCR0_VMIDPNE | sCR0_PTM);

        /* Enable client access, but bypass when no mapping is found */
        reg &= ~(sCR0_CLIENTPD | sCR0_USFCFG);

        /* Disable forced broadcasting */
        reg &= ~sCR0_FB;

        /* Don't upgrade barriers */
        reg &= ~(sCR0_BSU_MASK << sCR0_BSU_SHIFT);

        /* Push the button */
        arm_smmu_tlb_sync(smmu);
        writel_relaxed(reg, gr0_base + ARM_SMMU_GR0_sCR0);
}

static int arm_smmu_id_size_to_bits(int size)
{
        switch (size) {
        case 0:
                return 32;
        case 1:
                return 36;
        case 2:
                return 40;
        case 3:
                return 42;
        case 4:
                return 44;
        case 5:
        default:
                return 48;
        }
}

static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
{
        unsigned long size;
        void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
        u32 id;

        dev_notice(smmu->dev, "probing hardware configuration...\n");

        /* Primecell ID */
        id = readl_relaxed(gr0_base + ARM_SMMU_GR0_PIDR2);
        smmu->version = ((id >> PIDR2_ARCH_SHIFT) & PIDR2_ARCH_MASK) + 1;
        dev_notice(smmu->dev, "SMMUv%d with:\n", smmu->version);

        /* ID0 */
        id = readl_relaxed(gr0_base + ARM_SMMU_GR0_ID0);
#ifndef CONFIG_64BIT
        if (((id >> ID0_PTFS_SHIFT) & ID0_PTFS_MASK) == ID0_PTFS_V8_ONLY) {
                dev_err(smmu->dev, "\tno v7 descriptor support!\n");
                return -ENODEV;
        }
#endif
        if (id & ID0_S1TS) {
                smmu->features |= ARM_SMMU_FEAT_TRANS_S1;
                dev_notice(smmu->dev, "\tstage 1 translation\n");
        }

        if (id & ID0_S2TS) {
                smmu->features |= ARM_SMMU_FEAT_TRANS_S2;
                dev_notice(smmu->dev, "\tstage 2 translation\n");
        }

        if (id & ID0_NTS) {
                smmu->features |= ARM_SMMU_FEAT_TRANS_NESTED;
                dev_notice(smmu->dev, "\tnested translation\n");
        }

        if (!(smmu->features &
                (ARM_SMMU_FEAT_TRANS_S1 | ARM_SMMU_FEAT_TRANS_S2 |
                 ARM_SMMU_FEAT_TRANS_NESTED))) {
                dev_err(smmu->dev, "\tno translation support!\n");
                return -ENODEV;
        }

        if (id & ID0_CTTW) {
                smmu->features |= ARM_SMMU_FEAT_COHERENT_WALK;
                dev_notice(smmu->dev, "\tcoherent table walk\n");
        }

        if (id & ID0_SMS) {
                u32 smr, sid, mask;

                smmu->features |= ARM_SMMU_FEAT_STREAM_MATCH;
                smmu->num_mapping_groups = (id >> ID0_NUMSMRG_SHIFT) &
                                           ID0_NUMSMRG_MASK;
                if (smmu->num_mapping_groups == 0) {
                        dev_err(smmu->dev,
                                "stream-matching supported, but no SMRs present!\n");
                        return -ENODEV;
                }

                smr = SMR_MASK_MASK << SMR_MASK_SHIFT;
                smr |= (SMR_ID_MASK << SMR_ID_SHIFT);
                writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
                smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));

                mask = (smr >> SMR_MASK_SHIFT) & SMR_MASK_MASK;
                sid = (smr >> SMR_ID_SHIFT) & SMR_ID_MASK;
                if ((mask & sid) != sid) {
                        dev_err(smmu->dev,
                                "SMR mask bits (0x%x) insufficient for ID field (0x%x)\n",
                                mask, sid);
                        return -ENODEV;
                }

                dev_notice(smmu->dev,
                           "\tstream matching with %u register groups, mask 0x%x",
                           smmu->num_mapping_groups, mask);
        }

        /* ID1 */
        id = readl_relaxed(gr0_base + ARM_SMMU_GR0_ID1);
        smmu->pagesize = (id & ID1_PAGESIZE) ? SZ_64K : SZ_4K;

        /* Check for size mismatch of SMMU address space from mapped region */
        size = 1 << (((id >> ID1_NUMPAGENDXB_SHIFT) & ID1_NUMPAGENDXB_MASK) + 1);
        size *= (smmu->pagesize << 1);
        if (smmu->size != size)
                dev_warn(smmu->dev, "SMMU address space size (0x%lx) differs "
                        "from mapped region size (0x%lx)!\n", size, smmu->size);

        smmu->num_s2_context_banks = (id >> ID1_NUMS2CB_SHIFT) &
                                      ID1_NUMS2CB_MASK;
        smmu->num_context_banks = (id >> ID1_NUMCB_SHIFT) & ID1_NUMCB_MASK;
        if (smmu->num_s2_context_banks > smmu->num_context_banks) {
                dev_err(smmu->dev, "impossible number of S2 context banks!\n");
                return -ENODEV;
        }
        dev_notice(smmu->dev, "\t%u context banks (%u stage-2 only)\n",
                   smmu->num_context_banks, smmu->num_s2_context_banks);

        /* ID2 */
        id = readl_relaxed(gr0_base + ARM_SMMU_GR0_ID2);
        size = arm_smmu_id_size_to_bits((id >> ID2_IAS_SHIFT) & ID2_IAS_MASK);

        /*
         * Stage-1 output limited by stage-2 input size due to pgd
         * allocation (PTRS_PER_PGD).
         */
#ifdef CONFIG_64BIT
        /* Current maximum output size of 39 bits */
        smmu->s1_output_size = min(39UL, size);
#else
        smmu->s1_output_size = min(32UL, size);
#endif

        /* The stage-2 output mask is also applied for bypass */
        size = arm_smmu_id_size_to_bits((id >> ID2_OAS_SHIFT) & ID2_OAS_MASK);
        smmu->s2_output_size = min((unsigned long)PHYS_MASK_SHIFT, size);

        if (smmu->version == 1) {
                smmu->input_size = 32;
        } else {
#ifdef CONFIG_64BIT
                size = (id >> ID2_UBS_SHIFT) & ID2_UBS_MASK;
                size = min(39, arm_smmu_id_size_to_bits(size));
#else
                size = 32;
#endif
                smmu->input_size = size;

                if ((PAGE_SIZE == SZ_4K && !(id & ID2_PTFS_4K)) ||
                    (PAGE_SIZE == SZ_64K && !(id & ID2_PTFS_64K)) ||
                    (PAGE_SIZE != SZ_4K && PAGE_SIZE != SZ_64K)) {
                        dev_err(smmu->dev, "CPU page size 0x%lx unsupported\n",
                                PAGE_SIZE);
                        return -ENODEV;
                }
        }

        dev_notice(smmu->dev,
                   "\t%lu-bit VA, %lu-bit IPA, %lu-bit PA\n",
                   smmu->input_size, smmu->s1_output_size, smmu->s2_output_size);
        return 0;
}

static int arm_smmu_device_dt_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct arm_smmu_device *smmu;
        struct device_node *dev_node;
        struct device *dev = &pdev->dev;
        struct rb_node *node;
        struct of_phandle_args masterspec;
        int num_irqs, i, err;

        smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
        if (!smmu) {
                dev_err(dev, "failed to allocate arm_smmu_device\n");
                return -ENOMEM;
        }
        smmu->dev = dev;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        smmu->base = devm_ioremap_resource(dev, res);
        if (IS_ERR(smmu->base))
                return PTR_ERR(smmu->base);
        smmu->size = resource_size(res);

        if (of_property_read_u32(dev->of_node, "#global-interrupts",
                                 &smmu->num_global_irqs)) {
                dev_err(dev, "missing #global-interrupts property\n");
                return -ENODEV;
        }

        num_irqs = 0;
        while ((res = platform_get_resource(pdev, IORESOURCE_IRQ, num_irqs))) {
                num_irqs++;
                if (num_irqs > smmu->num_global_irqs)
                        smmu->num_context_irqs++;
        }

        if (!smmu->num_context_irqs) {
                dev_err(dev, "found %d interrupts but expected at least %d\n",
                        num_irqs, smmu->num_global_irqs + 1);
                return -ENODEV;
        }

        smmu->irqs = devm_kzalloc(dev, sizeof(*smmu->irqs) * num_irqs,
                                  GFP_KERNEL);
        if (!smmu->irqs) {
                dev_err(dev, "failed to allocate %d irqs\n", num_irqs);
                return -ENOMEM;
        }

        for (i = 0; i < num_irqs; ++i) {
                int irq = platform_get_irq(pdev, i);
                if (irq < 0) {
                        dev_err(dev, "failed to get irq index %d\n", i);
                        return -ENODEV;
                }
                smmu->irqs[i] = irq;
        }

        i = 0;
        smmu->masters = RB_ROOT;
        while (!of_parse_phandle_with_args(dev->of_node, "mmu-masters",
                                           "#stream-id-cells", i,
                                           &masterspec)) {
                err = register_smmu_master(smmu, dev, &masterspec);
                if (err) {
                        dev_err(dev, "failed to add master %s\n",
                                masterspec.np->name);
                        goto out_put_masters;
                }

                i++;
        }
        dev_notice(dev, "registered %d master devices\n", i);

        if ((dev_node = of_parse_phandle(dev->of_node, "smmu-parent", 0)))
                smmu->parent_of_node = dev_node;

        err = arm_smmu_device_cfg_probe(smmu);
        if (err)
                goto out_put_parent;

        if (smmu->version > 1 &&
            smmu->num_context_banks != smmu->num_context_irqs) {
                dev_err(dev,
                        "found only %d context interrupt(s) but %d required\n",
                        smmu->num_context_irqs, smmu->num_context_banks);
                err = -ENODEV;
                goto out_put_parent;
        }

        for (i = 0; i < smmu->num_global_irqs; ++i) {
                err = request_irq(smmu->irqs[i],
                                  arm_smmu_global_fault,
                                  IRQF_SHARED,
                                  "arm-smmu global fault",
                                  smmu);
                if (err) {
                        dev_err(dev, "failed to request global IRQ %d (%u)\n",
                                i, smmu->irqs[i]);
                        goto out_free_irqs;
                }
        }

        INIT_LIST_HEAD(&smmu->list);
        spin_lock(&arm_smmu_devices_lock);
        list_add(&smmu->list, &arm_smmu_devices);
        spin_unlock(&arm_smmu_devices_lock);

        arm_smmu_device_reset(smmu);
        return 0;

out_free_irqs:
        while (i--)
                free_irq(smmu->irqs[i], smmu);

out_put_parent:
        if (smmu->parent_of_node)
                of_node_put(smmu->parent_of_node);

out_put_masters:
        for (node = rb_first(&smmu->masters); node; node = rb_next(node)) {
                struct arm_smmu_master *master;
                master = container_of(node, struct arm_smmu_master, node);
                of_node_put(master->of_node);
        }

        return err;
}

static int arm_smmu_device_remove(struct platform_device *pdev)
{
        int i;
        struct device *dev = &pdev->dev;
        struct arm_smmu_device *curr, *smmu = NULL;
        struct rb_node *node;

        spin_lock(&arm_smmu_devices_lock);
        list_for_each_entry(curr, &arm_smmu_devices, list) {
                if (curr->dev == dev) {
                        smmu = curr;
                        list_del(&smmu->list);
                        break;
                }
        }
        spin_unlock(&arm_smmu_devices_lock);

        if (!smmu)
                return -ENODEV;

        if (smmu->parent_of_node)
                of_node_put(smmu->parent_of_node);

        for (node = rb_first(&smmu->masters); node; node = rb_next(node)) {
                struct arm_smmu_master *master;
                master = container_of(node, struct arm_smmu_master, node);
                of_node_put(master->of_node);
        }

        if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
                dev_err(dev, "removing device with active domains!\n");

        for (i = 0; i < smmu->num_global_irqs; ++i)
                free_irq(smmu->irqs[i], smmu);

        /* Turn the thing off */
        writel_relaxed(sCR0_CLIENTPD, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_sCR0);
        return 0;
}

#ifdef CONFIG_OF
static struct of_device_id arm_smmu_of_match[] = {
        { .compatible = "arm,smmu-v1", },
        { .compatible = "arm,smmu-v2", },
        { .compatible = "arm,mmu-400", },
        { .compatible = "arm,mmu-500", },
        { },
};
MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
#endif

static struct platform_driver arm_smmu_driver = {
        .driver = {
                .owner          = THIS_MODULE,
                .name           = "arm-smmu",
                .of_match_table = of_match_ptr(arm_smmu_of_match),
        },
        .probe  = arm_smmu_device_dt_probe,
        .remove = arm_smmu_device_remove,
};

static int __init arm_smmu_init(void)
{
        int ret;

        ret = platform_driver_register(&arm_smmu_driver);
        if (ret)
                return ret;

        /* Oh, for a proper bus abstraction */
        if (!iommu_present(&platform_bus_type))
                bus_set_iommu(&platform_bus_type, &arm_smmu_ops);

        if (!iommu_present(&amba_bustype))
                bus_set_iommu(&amba_bustype, &arm_smmu_ops);

        return 0;
}

static void __exit arm_smmu_exit(void)
{
        return platform_driver_unregister(&arm_smmu_driver);
}

subsys_initcall(arm_smmu_init);
module_exit(arm_smmu_exit);

MODULE_DESCRIPTION("IOMMU API for ARM architected SMMU implementations");
MODULE_AUTHOR("Will Deacon <will.deacon@arm.com>");
MODULE_LICENSE("GPL v2");