Linux 4.19.133

[linux/fpc-iii.git] / drivers / iommu / tegra-smmu.c

/*
 * Copyright (C) 2011-2014 NVIDIA CORPORATION.  All rights reserved.
 *
 * 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.
 */

#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/err.h>
#include <linux/iommu.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>

#include <soc/tegra/ahb.h>
#include <soc/tegra/mc.h>

struct tegra_smmu_group {
        struct list_head list;
        const struct tegra_smmu_group_soc *soc;
        struct iommu_group *group;
};

struct tegra_smmu {
        void __iomem *regs;
        struct device *dev;

        struct tegra_mc *mc;
        const struct tegra_smmu_soc *soc;

        struct list_head groups;

        unsigned long pfn_mask;
        unsigned long tlb_mask;

        unsigned long *asids;
        struct mutex lock;

        struct list_head list;

        struct dentry *debugfs;

        struct iommu_device iommu;      /* IOMMU Core code handle */
};

struct tegra_smmu_as {
        struct iommu_domain domain;
        struct tegra_smmu *smmu;
        unsigned int use_count;
        u32 *count;
        struct page **pts;
        struct page *pd;
        dma_addr_t pd_dma;
        unsigned id;
        u32 attr;
};

static struct tegra_smmu_as *to_smmu_as(struct iommu_domain *dom)
{
        return container_of(dom, struct tegra_smmu_as, domain);
}

static inline void smmu_writel(struct tegra_smmu *smmu, u32 value,
                               unsigned long offset)
{
        writel(value, smmu->regs + offset);
}

static inline u32 smmu_readl(struct tegra_smmu *smmu, unsigned long offset)
{
        return readl(smmu->regs + offset);
}

#define SMMU_CONFIG 0x010
#define  SMMU_CONFIG_ENABLE (1 << 0)

#define SMMU_TLB_CONFIG 0x14
#define  SMMU_TLB_CONFIG_HIT_UNDER_MISS (1 << 29)
#define  SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION (1 << 28)
#define  SMMU_TLB_CONFIG_ACTIVE_LINES(smmu) \
        ((smmu)->soc->num_tlb_lines & (smmu)->tlb_mask)

#define SMMU_PTC_CONFIG 0x18
#define  SMMU_PTC_CONFIG_ENABLE (1 << 29)
#define  SMMU_PTC_CONFIG_REQ_LIMIT(x) (((x) & 0x0f) << 24)
#define  SMMU_PTC_CONFIG_INDEX_MAP(x) ((x) & 0x3f)

#define SMMU_PTB_ASID 0x01c
#define  SMMU_PTB_ASID_VALUE(x) ((x) & 0x7f)

#define SMMU_PTB_DATA 0x020
#define  SMMU_PTB_DATA_VALUE(dma, attr) ((dma) >> 12 | (attr))

#define SMMU_MK_PDE(dma, attr) ((dma) >> SMMU_PTE_SHIFT | (attr))

#define SMMU_TLB_FLUSH 0x030
#define  SMMU_TLB_FLUSH_VA_MATCH_ALL     (0 << 0)
#define  SMMU_TLB_FLUSH_VA_MATCH_SECTION (2 << 0)
#define  SMMU_TLB_FLUSH_VA_MATCH_GROUP   (3 << 0)
#define  SMMU_TLB_FLUSH_VA_SECTION(addr) ((((addr) & 0xffc00000) >> 12) | \
                                          SMMU_TLB_FLUSH_VA_MATCH_SECTION)
#define  SMMU_TLB_FLUSH_VA_GROUP(addr)   ((((addr) & 0xffffc000) >> 12) | \
                                          SMMU_TLB_FLUSH_VA_MATCH_GROUP)
#define  SMMU_TLB_FLUSH_ASID_MATCH       (1 << 31)

#define SMMU_PTC_FLUSH 0x034
#define  SMMU_PTC_FLUSH_TYPE_ALL (0 << 0)
#define  SMMU_PTC_FLUSH_TYPE_ADR (1 << 0)

#define SMMU_PTC_FLUSH_HI 0x9b8
#define  SMMU_PTC_FLUSH_HI_MASK 0x3

/* per-SWGROUP SMMU_*_ASID register */
#define SMMU_ASID_ENABLE (1 << 31)
#define SMMU_ASID_MASK 0x7f
#define SMMU_ASID_VALUE(x) ((x) & SMMU_ASID_MASK)

/* page table definitions */
#define SMMU_NUM_PDE 1024
#define SMMU_NUM_PTE 1024

#define SMMU_SIZE_PD (SMMU_NUM_PDE * 4)
#define SMMU_SIZE_PT (SMMU_NUM_PTE * 4)

#define SMMU_PDE_SHIFT 22
#define SMMU_PTE_SHIFT 12

#define SMMU_PD_READABLE        (1 << 31)
#define SMMU_PD_WRITABLE        (1 << 30)
#define SMMU_PD_NONSECURE       (1 << 29)

#define SMMU_PDE_READABLE       (1 << 31)
#define SMMU_PDE_WRITABLE       (1 << 30)
#define SMMU_PDE_NONSECURE      (1 << 29)
#define SMMU_PDE_NEXT           (1 << 28)

#define SMMU_PTE_READABLE       (1 << 31)
#define SMMU_PTE_WRITABLE       (1 << 30)
#define SMMU_PTE_NONSECURE      (1 << 29)

#define SMMU_PDE_ATTR           (SMMU_PDE_READABLE | SMMU_PDE_WRITABLE | \
                                 SMMU_PDE_NONSECURE)
#define SMMU_PTE_ATTR           (SMMU_PTE_READABLE | SMMU_PTE_WRITABLE | \
                                 SMMU_PTE_NONSECURE)

static unsigned int iova_pd_index(unsigned long iova)
{
        return (iova >> SMMU_PDE_SHIFT) & (SMMU_NUM_PDE - 1);
}

static unsigned int iova_pt_index(unsigned long iova)
{
        return (iova >> SMMU_PTE_SHIFT) & (SMMU_NUM_PTE - 1);
}

static bool smmu_dma_addr_valid(struct tegra_smmu *smmu, dma_addr_t addr)
{
        addr >>= 12;
        return (addr & smmu->pfn_mask) == addr;
}

static dma_addr_t smmu_pde_to_dma(struct tegra_smmu *smmu, u32 pde)
{
        return (dma_addr_t)(pde & smmu->pfn_mask) << 12;
}

static void smmu_flush_ptc_all(struct tegra_smmu *smmu)
{
        smmu_writel(smmu, SMMU_PTC_FLUSH_TYPE_ALL, SMMU_PTC_FLUSH);
}

static inline void smmu_flush_ptc(struct tegra_smmu *smmu, dma_addr_t dma,
                                  unsigned long offset)
{
        u32 value;

        offset &= ~(smmu->mc->soc->atom_size - 1);

        if (smmu->mc->soc->num_address_bits > 32) {
#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
                value = (dma >> 32) & SMMU_PTC_FLUSH_HI_MASK;
#else
                value = 0;
#endif
                smmu_writel(smmu, value, SMMU_PTC_FLUSH_HI);
        }

        value = (dma + offset) | SMMU_PTC_FLUSH_TYPE_ADR;
        smmu_writel(smmu, value, SMMU_PTC_FLUSH);
}

static inline void smmu_flush_tlb(struct tegra_smmu *smmu)
{
        smmu_writel(smmu, SMMU_TLB_FLUSH_VA_MATCH_ALL, SMMU_TLB_FLUSH);
}

static inline void smmu_flush_tlb_asid(struct tegra_smmu *smmu,
                                       unsigned long asid)
{
        u32 value;

        if (smmu->soc->num_asids == 4)
                value = (asid & 0x3) << 29;
        else
                value = (asid & 0x7f) << 24;

        value |= SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_VA_MATCH_ALL;
        smmu_writel(smmu, value, SMMU_TLB_FLUSH);
}

static inline void smmu_flush_tlb_section(struct tegra_smmu *smmu,
                                          unsigned long asid,
                                          unsigned long iova)
{
        u32 value;

        if (smmu->soc->num_asids == 4)
                value = (asid & 0x3) << 29;
        else
                value = (asid & 0x7f) << 24;

        value |= SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_VA_SECTION(iova);
        smmu_writel(smmu, value, SMMU_TLB_FLUSH);
}

static inline void smmu_flush_tlb_group(struct tegra_smmu *smmu,
                                        unsigned long asid,
                                        unsigned long iova)
{
        u32 value;

        if (smmu->soc->num_asids == 4)
                value = (asid & 0x3) << 29;
        else
                value = (asid & 0x7f) << 24;

        value |= SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_VA_GROUP(iova);
        smmu_writel(smmu, value, SMMU_TLB_FLUSH);
}

static inline void smmu_flush(struct tegra_smmu *smmu)
{
        smmu_readl(smmu, SMMU_CONFIG);
}

static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
{
        unsigned long id;

        mutex_lock(&smmu->lock);

        id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
        if (id >= smmu->soc->num_asids) {
                mutex_unlock(&smmu->lock);
                return -ENOSPC;
        }

        set_bit(id, smmu->asids);
        *idp = id;

        mutex_unlock(&smmu->lock);
        return 0;
}

static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
{
        mutex_lock(&smmu->lock);
        clear_bit(id, smmu->asids);
        mutex_unlock(&smmu->lock);
}

static bool tegra_smmu_capable(enum iommu_cap cap)
{
        return false;
}

static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type)
{
        struct tegra_smmu_as *as;

        if (type != IOMMU_DOMAIN_UNMANAGED)
                return NULL;

        as = kzalloc(sizeof(*as), GFP_KERNEL);
        if (!as)
                return NULL;

        as->attr = SMMU_PD_READABLE | SMMU_PD_WRITABLE | SMMU_PD_NONSECURE;

        as->pd = alloc_page(GFP_KERNEL | __GFP_DMA | __GFP_ZERO);
        if (!as->pd) {
                kfree(as);
                return NULL;
        }

        as->count = kcalloc(SMMU_NUM_PDE, sizeof(u32), GFP_KERNEL);
        if (!as->count) {
                __free_page(as->pd);
                kfree(as);
                return NULL;
        }

        as->pts = kcalloc(SMMU_NUM_PDE, sizeof(*as->pts), GFP_KERNEL);
        if (!as->pts) {
                kfree(as->count);
                __free_page(as->pd);
                kfree(as);
                return NULL;
        }

        /* setup aperture */
        as->domain.geometry.aperture_start = 0;
        as->domain.geometry.aperture_end = 0xffffffff;
        as->domain.geometry.force_aperture = true;

        return &as->domain;
}

static void tegra_smmu_domain_free(struct iommu_domain *domain)
{
        struct tegra_smmu_as *as = to_smmu_as(domain);

        /* TODO: free page directory and page tables */

        kfree(as);
}

static const struct tegra_smmu_swgroup *
tegra_smmu_find_swgroup(struct tegra_smmu *smmu, unsigned int swgroup)
{
        const struct tegra_smmu_swgroup *group = NULL;
        unsigned int i;

        for (i = 0; i < smmu->soc->num_swgroups; i++) {
                if (smmu->soc->swgroups[i].swgroup == swgroup) {
                        group = &smmu->soc->swgroups[i];
                        break;
                }
        }

        return group;
}

static void tegra_smmu_enable(struct tegra_smmu *smmu, unsigned int swgroup,
                              unsigned int asid)
{
        const struct tegra_smmu_swgroup *group;
        unsigned int i;
        u32 value;

        for (i = 0; i < smmu->soc->num_clients; i++) {
                const struct tegra_mc_client *client = &smmu->soc->clients[i];

                if (client->swgroup != swgroup)
                        continue;

                value = smmu_readl(smmu, client->smmu.reg);
                value |= BIT(client->smmu.bit);
                smmu_writel(smmu, value, client->smmu.reg);
        }

        group = tegra_smmu_find_swgroup(smmu, swgroup);
        if (group) {
                value = smmu_readl(smmu, group->reg);
                value &= ~SMMU_ASID_MASK;
                value |= SMMU_ASID_VALUE(asid);
                value |= SMMU_ASID_ENABLE;
                smmu_writel(smmu, value, group->reg);
        }
}

static void tegra_smmu_disable(struct tegra_smmu *smmu, unsigned int swgroup,
                               unsigned int asid)
{
        const struct tegra_smmu_swgroup *group;
        unsigned int i;
        u32 value;

        group = tegra_smmu_find_swgroup(smmu, swgroup);
        if (group) {
                value = smmu_readl(smmu, group->reg);
                value &= ~SMMU_ASID_MASK;
                value |= SMMU_ASID_VALUE(asid);
                value &= ~SMMU_ASID_ENABLE;
                smmu_writel(smmu, value, group->reg);
        }

        for (i = 0; i < smmu->soc->num_clients; i++) {
                const struct tegra_mc_client *client = &smmu->soc->clients[i];

                if (client->swgroup != swgroup)
                        continue;

                value = smmu_readl(smmu, client->smmu.reg);
                value &= ~BIT(client->smmu.bit);
                smmu_writel(smmu, value, client->smmu.reg);
        }
}

static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
                                 struct tegra_smmu_as *as)
{
        u32 value;
        int err;

        if (as->use_count > 0) {
                as->use_count++;
                return 0;
        }

        as->pd_dma = dma_map_page(smmu->dev, as->pd, 0, SMMU_SIZE_PD,
                                  DMA_TO_DEVICE);
        if (dma_mapping_error(smmu->dev, as->pd_dma))
                return -ENOMEM;

        /* We can't handle 64-bit DMA addresses */
        if (!smmu_dma_addr_valid(smmu, as->pd_dma)) {
                err = -ENOMEM;
                goto err_unmap;
        }

        err = tegra_smmu_alloc_asid(smmu, &as->id);
        if (err < 0)
                goto err_unmap;

        smmu_flush_ptc(smmu, as->pd_dma, 0);
        smmu_flush_tlb_asid(smmu, as->id);

        smmu_writel(smmu, as->id & 0x7f, SMMU_PTB_ASID);
        value = SMMU_PTB_DATA_VALUE(as->pd_dma, as->attr);
        smmu_writel(smmu, value, SMMU_PTB_DATA);
        smmu_flush(smmu);

        as->smmu = smmu;
        as->use_count++;

        return 0;

err_unmap:
        dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE);
        return err;
}

static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
                                    struct tegra_smmu_as *as)
{
        if (--as->use_count > 0)
                return;

        tegra_smmu_free_asid(smmu, as->id);

        dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE);

        as->smmu = NULL;
}

static int tegra_smmu_attach_dev(struct iommu_domain *domain,
                                 struct device *dev)
{
        struct tegra_smmu *smmu = dev->archdata.iommu;
        struct tegra_smmu_as *as = to_smmu_as(domain);
        struct device_node *np = dev->of_node;
        struct of_phandle_args args;
        unsigned int index = 0;
        int err = 0;

        while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
                                           &args)) {
                unsigned int swgroup = args.args[0];

                if (args.np != smmu->dev->of_node) {
                        of_node_put(args.np);
                        continue;
                }

                of_node_put(args.np);

                err = tegra_smmu_as_prepare(smmu, as);
                if (err < 0)
                        return err;

                tegra_smmu_enable(smmu, swgroup, as->id);
                index++;
        }

        if (index == 0)
                return -ENODEV;

        return 0;
}

static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
{
        struct tegra_smmu_as *as = to_smmu_as(domain);
        struct device_node *np = dev->of_node;
        struct tegra_smmu *smmu = as->smmu;
        struct of_phandle_args args;
        unsigned int index = 0;

        while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
                                           &args)) {
                unsigned int swgroup = args.args[0];

                if (args.np != smmu->dev->of_node) {
                        of_node_put(args.np);
                        continue;
                }

                of_node_put(args.np);

                tegra_smmu_disable(smmu, swgroup, as->id);
                tegra_smmu_as_unprepare(smmu, as);
                index++;
        }
}

static void tegra_smmu_set_pde(struct tegra_smmu_as *as, unsigned long iova,
                               u32 value)
{
        unsigned int pd_index = iova_pd_index(iova);
        struct tegra_smmu *smmu = as->smmu;
        u32 *pd = page_address(as->pd);
        unsigned long offset = pd_index * sizeof(*pd);

        /* Set the page directory entry first */
        pd[pd_index] = value;

        /* The flush the page directory entry from caches */
        dma_sync_single_range_for_device(smmu->dev, as->pd_dma, offset,
                                         sizeof(*pd), DMA_TO_DEVICE);

        /* And flush the iommu */
        smmu_flush_ptc(smmu, as->pd_dma, offset);
        smmu_flush_tlb_section(smmu, as->id, iova);
        smmu_flush(smmu);
}

static u32 *tegra_smmu_pte_offset(struct page *pt_page, unsigned long iova)
{
        u32 *pt = page_address(pt_page);

        return pt + iova_pt_index(iova);
}

static u32 *tegra_smmu_pte_lookup(struct tegra_smmu_as *as, unsigned long iova,
                                  dma_addr_t *dmap)
{
        unsigned int pd_index = iova_pd_index(iova);
        struct tegra_smmu *smmu = as->smmu;
        struct page *pt_page;
        u32 *pd;

        pt_page = as->pts[pd_index];
        if (!pt_page)
                return NULL;

        pd = page_address(as->pd);
        *dmap = smmu_pde_to_dma(smmu, pd[pd_index]);

        return tegra_smmu_pte_offset(pt_page, iova);
}

static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
                       dma_addr_t *dmap)
{
        unsigned int pde = iova_pd_index(iova);
        struct tegra_smmu *smmu = as->smmu;

        if (!as->pts[pde]) {
                struct page *page;
                dma_addr_t dma;

                page = alloc_page(GFP_KERNEL | __GFP_DMA | __GFP_ZERO);
                if (!page)
                        return NULL;

                dma = dma_map_page(smmu->dev, page, 0, SMMU_SIZE_PT,
                                   DMA_TO_DEVICE);
                if (dma_mapping_error(smmu->dev, dma)) {
                        __free_page(page);
                        return NULL;
                }

                if (!smmu_dma_addr_valid(smmu, dma)) {
                        dma_unmap_page(smmu->dev, dma, SMMU_SIZE_PT,
                                       DMA_TO_DEVICE);
                        __free_page(page);
                        return NULL;
                }

                as->pts[pde] = page;

                tegra_smmu_set_pde(as, iova, SMMU_MK_PDE(dma, SMMU_PDE_ATTR |
                                                              SMMU_PDE_NEXT));

                *dmap = dma;
        } else {
                u32 *pd = page_address(as->pd);

                *dmap = smmu_pde_to_dma(smmu, pd[pde]);
        }

        return tegra_smmu_pte_offset(as->pts[pde], iova);
}

static void tegra_smmu_pte_get_use(struct tegra_smmu_as *as, unsigned long iova)
{
        unsigned int pd_index = iova_pd_index(iova);

        as->count[pd_index]++;
}

static void tegra_smmu_pte_put_use(struct tegra_smmu_as *as, unsigned long iova)
{
        unsigned int pde = iova_pd_index(iova);
        struct page *page = as->pts[pde];

        /*
         * When no entries in this page table are used anymore, return the
         * memory page to the system.
         */
        if (--as->count[pde] == 0) {
                struct tegra_smmu *smmu = as->smmu;
                u32 *pd = page_address(as->pd);
                dma_addr_t pte_dma = smmu_pde_to_dma(smmu, pd[pde]);

                tegra_smmu_set_pde(as, iova, 0);

                dma_unmap_page(smmu->dev, pte_dma, SMMU_SIZE_PT, DMA_TO_DEVICE);
                __free_page(page);
                as->pts[pde] = NULL;
        }
}

static void tegra_smmu_set_pte(struct tegra_smmu_as *as, unsigned long iova,
                               u32 *pte, dma_addr_t pte_dma, u32 val)
{
        struct tegra_smmu *smmu = as->smmu;
        unsigned long offset = offset_in_page(pte);

        *pte = val;

        dma_sync_single_range_for_device(smmu->dev, pte_dma, offset,
                                         4, DMA_TO_DEVICE);
        smmu_flush_ptc(smmu, pte_dma, offset);
        smmu_flush_tlb_group(smmu, as->id, iova);
        smmu_flush(smmu);
}

static int tegra_smmu_map(struct iommu_domain *domain, unsigned long iova,
                          phys_addr_t paddr, size_t size, int prot)
{
        struct tegra_smmu_as *as = to_smmu_as(domain);
        dma_addr_t pte_dma;
        u32 *pte;

        pte = as_get_pte(as, iova, &pte_dma);
        if (!pte)
                return -ENOMEM;

        /* If we aren't overwriting a pre-existing entry, increment use */
        if (*pte == 0)
                tegra_smmu_pte_get_use(as, iova);

        tegra_smmu_set_pte(as, iova, pte, pte_dma,
                           __phys_to_pfn(paddr) | SMMU_PTE_ATTR);

        return 0;
}

static size_t tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
                               size_t size)
{
        struct tegra_smmu_as *as = to_smmu_as(domain);
        dma_addr_t pte_dma;
        u32 *pte;

        pte = tegra_smmu_pte_lookup(as, iova, &pte_dma);
        if (!pte || !*pte)
                return 0;

        tegra_smmu_set_pte(as, iova, pte, pte_dma, 0);
        tegra_smmu_pte_put_use(as, iova);

        return size;
}

static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
                                           dma_addr_t iova)
{
        struct tegra_smmu_as *as = to_smmu_as(domain);
        unsigned long pfn;
        dma_addr_t pte_dma;
        u32 *pte;

        pte = tegra_smmu_pte_lookup(as, iova, &pte_dma);
        if (!pte || !*pte)
                return 0;

        pfn = *pte & as->smmu->pfn_mask;

        return PFN_PHYS(pfn);
}

static struct tegra_smmu *tegra_smmu_find(struct device_node *np)
{
        struct platform_device *pdev;
        struct tegra_mc *mc;

        pdev = of_find_device_by_node(np);
        if (!pdev)
                return NULL;

        mc = platform_get_drvdata(pdev);
        if (!mc)
                return NULL;

        return mc->smmu;
}

static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev,
                                struct of_phandle_args *args)
{
        const struct iommu_ops *ops = smmu->iommu.ops;
        int err;

        err = iommu_fwspec_init(dev, &dev->of_node->fwnode, ops);
        if (err < 0) {
                dev_err(dev, "failed to initialize fwspec: %d\n", err);
                return err;
        }

        err = ops->of_xlate(dev, args);
        if (err < 0) {
                dev_err(dev, "failed to parse SW group ID: %d\n", err);
                iommu_fwspec_free(dev);
                return err;
        }

        return 0;
}

static int tegra_smmu_add_device(struct device *dev)
{
        struct device_node *np = dev->of_node;
        struct tegra_smmu *smmu = NULL;
        struct iommu_group *group;
        struct of_phandle_args args;
        unsigned int index = 0;
        int err;

        while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
                                          &args) == 0) {
                smmu = tegra_smmu_find(args.np);
                if (smmu) {
                        err = tegra_smmu_configure(smmu, dev, &args);
                        of_node_put(args.np);

                        if (err < 0)
                                return err;

                        /*
                         * Only a single IOMMU master interface is currently
                         * supported by the Linux kernel, so abort after the
                         * first match.
                         */
                        dev->archdata.iommu = smmu;

                        iommu_device_link(&smmu->iommu, dev);

                        break;
                }

                of_node_put(args.np);
                index++;
        }

        if (!smmu)
                return -ENODEV;

        group = iommu_group_get_for_dev(dev);
        if (IS_ERR(group))
                return PTR_ERR(group);

        iommu_group_put(group);

        return 0;
}

static void tegra_smmu_remove_device(struct device *dev)
{
        struct tegra_smmu *smmu = dev->archdata.iommu;

        if (smmu)
                iommu_device_unlink(&smmu->iommu, dev);

        dev->archdata.iommu = NULL;
        iommu_group_remove_device(dev);
}

static const struct tegra_smmu_group_soc *
tegra_smmu_find_group(struct tegra_smmu *smmu, unsigned int swgroup)
{
        unsigned int i, j;

        for (i = 0; i < smmu->soc->num_groups; i++)
                for (j = 0; j < smmu->soc->groups[i].num_swgroups; j++)
                        if (smmu->soc->groups[i].swgroups[j] == swgroup)
                                return &smmu->soc->groups[i];

        return NULL;
}

static struct iommu_group *tegra_smmu_group_get(struct tegra_smmu *smmu,
                                                unsigned int swgroup)
{
        const struct tegra_smmu_group_soc *soc;
        struct tegra_smmu_group *group;

        soc = tegra_smmu_find_group(smmu, swgroup);
        if (!soc)
                return NULL;

        mutex_lock(&smmu->lock);

        list_for_each_entry(group, &smmu->groups, list)
                if (group->soc == soc) {
                        mutex_unlock(&smmu->lock);
                        return group->group;
                }

        group = devm_kzalloc(smmu->dev, sizeof(*group), GFP_KERNEL);
        if (!group) {
                mutex_unlock(&smmu->lock);
                return NULL;
        }

        INIT_LIST_HEAD(&group->list);
        group->soc = soc;

        group->group = iommu_group_alloc();
        if (IS_ERR(group->group)) {
                devm_kfree(smmu->dev, group);
                mutex_unlock(&smmu->lock);
                return NULL;
        }

        list_add_tail(&group->list, &smmu->groups);
        mutex_unlock(&smmu->lock);

        return group->group;
}

static struct iommu_group *tegra_smmu_device_group(struct device *dev)
{
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;
        struct tegra_smmu *smmu = dev->archdata.iommu;
        struct iommu_group *group;

        group = tegra_smmu_group_get(smmu, fwspec->ids[0]);
        if (!group)
                group = generic_device_group(dev);

        return group;
}

static int tegra_smmu_of_xlate(struct device *dev,
                               struct of_phandle_args *args)
{
        u32 id = args->args[0];

        return iommu_fwspec_add_ids(dev, &id, 1);
}

static const struct iommu_ops tegra_smmu_ops = {
        .capable = tegra_smmu_capable,
        .domain_alloc = tegra_smmu_domain_alloc,
        .domain_free = tegra_smmu_domain_free,
        .attach_dev = tegra_smmu_attach_dev,
        .detach_dev = tegra_smmu_detach_dev,
        .add_device = tegra_smmu_add_device,
        .remove_device = tegra_smmu_remove_device,
        .device_group = tegra_smmu_device_group,
        .map = tegra_smmu_map,
        .unmap = tegra_smmu_unmap,
        .iova_to_phys = tegra_smmu_iova_to_phys,
        .of_xlate = tegra_smmu_of_xlate,
        .pgsize_bitmap = SZ_4K,
};

static void tegra_smmu_ahb_enable(void)
{
        static const struct of_device_id ahb_match[] = {
                { .compatible = "nvidia,tegra30-ahb", },
                { }
        };
        struct device_node *ahb;

        ahb = of_find_matching_node(NULL, ahb_match);
        if (ahb) {
                tegra_ahb_enable_smmu(ahb);
                of_node_put(ahb);
        }
}

static int tegra_smmu_swgroups_show(struct seq_file *s, void *data)
{
        struct tegra_smmu *smmu = s->private;
        unsigned int i;
        u32 value;

        seq_printf(s, "swgroup    enabled  ASID\n");
        seq_printf(s, "------------------------\n");

        for (i = 0; i < smmu->soc->num_swgroups; i++) {
                const struct tegra_smmu_swgroup *group = &smmu->soc->swgroups[i];
                const char *status;
                unsigned int asid;

                value = smmu_readl(smmu, group->reg);

                if (value & SMMU_ASID_ENABLE)
                        status = "yes";
                else
                        status = "no";

                asid = value & SMMU_ASID_MASK;

                seq_printf(s, "%-9s  %-7s  %#04x\n", group->name, status,
                           asid);
        }

        return 0;
}

static int tegra_smmu_swgroups_open(struct inode *inode, struct file *file)
{
        return single_open(file, tegra_smmu_swgroups_show, inode->i_private);
}

static const struct file_operations tegra_smmu_swgroups_fops = {
        .open = tegra_smmu_swgroups_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = single_release,
};

static int tegra_smmu_clients_show(struct seq_file *s, void *data)
{
        struct tegra_smmu *smmu = s->private;
        unsigned int i;
        u32 value;

        seq_printf(s, "client       enabled\n");
        seq_printf(s, "--------------------\n");

        for (i = 0; i < smmu->soc->num_clients; i++) {
                const struct tegra_mc_client *client = &smmu->soc->clients[i];
                const char *status;

                value = smmu_readl(smmu, client->smmu.reg);

                if (value & BIT(client->smmu.bit))
                        status = "yes";
                else
                        status = "no";

                seq_printf(s, "%-12s %s\n", client->name, status);
        }

        return 0;
}

static int tegra_smmu_clients_open(struct inode *inode, struct file *file)
{
        return single_open(file, tegra_smmu_clients_show, inode->i_private);
}

static const struct file_operations tegra_smmu_clients_fops = {
        .open = tegra_smmu_clients_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = single_release,
};

static void tegra_smmu_debugfs_init(struct tegra_smmu *smmu)
{
        smmu->debugfs = debugfs_create_dir("smmu", NULL);
        if (!smmu->debugfs)
                return;

        debugfs_create_file("swgroups", S_IRUGO, smmu->debugfs, smmu,
                            &tegra_smmu_swgroups_fops);
        debugfs_create_file("clients", S_IRUGO, smmu->debugfs, smmu,
                            &tegra_smmu_clients_fops);
}

static void tegra_smmu_debugfs_exit(struct tegra_smmu *smmu)
{
        debugfs_remove_recursive(smmu->debugfs);
}

struct tegra_smmu *tegra_smmu_probe(struct device *dev,
                                    const struct tegra_smmu_soc *soc,
                                    struct tegra_mc *mc)
{
        struct tegra_smmu *smmu;
        size_t size;
        u32 value;
        int err;

        /* This can happen on Tegra20 which doesn't have an SMMU */
        if (!soc)
                return NULL;

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

        /*
         * This is a bit of a hack. Ideally we'd want to simply return this
         * value. However the IOMMU registration process will attempt to add
         * all devices to the IOMMU when bus_set_iommu() is called. In order
         * not to rely on global variables to track the IOMMU instance, we
         * set it here so that it can be looked up from the .add_device()
         * callback via the IOMMU device's .drvdata field.
         */
        mc->smmu = smmu;

        size = BITS_TO_LONGS(soc->num_asids) * sizeof(long);

        smmu->asids = devm_kzalloc(dev, size, GFP_KERNEL);
        if (!smmu->asids)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&smmu->groups);
        mutex_init(&smmu->lock);

        smmu->regs = mc->regs;
        smmu->soc = soc;
        smmu->dev = dev;
        smmu->mc = mc;

        smmu->pfn_mask = BIT_MASK(mc->soc->num_address_bits - PAGE_SHIFT) - 1;
        dev_dbg(dev, "address bits: %u, PFN mask: %#lx\n",
                mc->soc->num_address_bits, smmu->pfn_mask);
        smmu->tlb_mask = (smmu->soc->num_tlb_lines << 1) - 1;
        dev_dbg(dev, "TLB lines: %u, mask: %#lx\n", smmu->soc->num_tlb_lines,
                smmu->tlb_mask);

        value = SMMU_PTC_CONFIG_ENABLE | SMMU_PTC_CONFIG_INDEX_MAP(0x3f);

        if (soc->supports_request_limit)
                value |= SMMU_PTC_CONFIG_REQ_LIMIT(8);

        smmu_writel(smmu, value, SMMU_PTC_CONFIG);

        value = SMMU_TLB_CONFIG_HIT_UNDER_MISS |
                SMMU_TLB_CONFIG_ACTIVE_LINES(smmu);

        if (soc->supports_round_robin_arbitration)
                value |= SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION;

        smmu_writel(smmu, value, SMMU_TLB_CONFIG);

        smmu_flush_ptc_all(smmu);
        smmu_flush_tlb(smmu);
        smmu_writel(smmu, SMMU_CONFIG_ENABLE, SMMU_CONFIG);
        smmu_flush(smmu);

        tegra_smmu_ahb_enable();

        err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
        if (err)
                return ERR_PTR(err);

        iommu_device_set_ops(&smmu->iommu, &tegra_smmu_ops);
        iommu_device_set_fwnode(&smmu->iommu, dev->fwnode);

        err = iommu_device_register(&smmu->iommu);
        if (err) {
                iommu_device_sysfs_remove(&smmu->iommu);
                return ERR_PTR(err);
        }

        err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
        if (err < 0) {
                iommu_device_unregister(&smmu->iommu);
                iommu_device_sysfs_remove(&smmu->iommu);
                return ERR_PTR(err);
        }

        if (IS_ENABLED(CONFIG_DEBUG_FS))
                tegra_smmu_debugfs_init(smmu);

        return smmu;
}

void tegra_smmu_remove(struct tegra_smmu *smmu)
{
        iommu_device_unregister(&smmu->iommu);
        iommu_device_sysfs_remove(&smmu->iommu);

        if (IS_ENABLED(CONFIG_DEBUG_FS))
                tegra_smmu_debugfs_exit(smmu);
}