Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cris-mirror.git] / drivers / iommu / exynos-iommu.c

/*
 * Copyright (c) 2011,2016 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#ifdef CONFIG_EXYNOS_IOMMU_DEBUG
#define DEBUG
#endif

#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/iommu.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/of.h>
#include <linux/of_iommu.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/dma-iommu.h>

typedef u32 sysmmu_iova_t;
typedef u32 sysmmu_pte_t;

/* We do not consider super section mapping (16MB) */
#define SECT_ORDER 20
#define LPAGE_ORDER 16
#define SPAGE_ORDER 12

#define SECT_SIZE (1 << SECT_ORDER)
#define LPAGE_SIZE (1 << LPAGE_ORDER)
#define SPAGE_SIZE (1 << SPAGE_ORDER)

#define SECT_MASK (~(SECT_SIZE - 1))
#define LPAGE_MASK (~(LPAGE_SIZE - 1))
#define SPAGE_MASK (~(SPAGE_SIZE - 1))

#define lv1ent_fault(sent) ((*(sent) == ZERO_LV2LINK) || \
                           ((*(sent) & 3) == 0) || ((*(sent) & 3) == 3))
#define lv1ent_zero(sent) (*(sent) == ZERO_LV2LINK)
#define lv1ent_page_zero(sent) ((*(sent) & 3) == 1)
#define lv1ent_page(sent) ((*(sent) != ZERO_LV2LINK) && \
                          ((*(sent) & 3) == 1))
#define lv1ent_section(sent) ((*(sent) & 3) == 2)

#define lv2ent_fault(pent) ((*(pent) & 3) == 0)
#define lv2ent_small(pent) ((*(pent) & 2) == 2)
#define lv2ent_large(pent) ((*(pent) & 3) == 1)

#ifdef CONFIG_BIG_ENDIAN
#warning "revisit driver if we can enable big-endian ptes"
#endif

/*
 * v1.x - v3.x SYSMMU supports 32bit physical and 32bit virtual address spaces
 * v5.0 introduced support for 36bit physical address space by shifting
 * all page entry values by 4 bits.
 * All SYSMMU controllers in the system support the address spaces of the same
 * size, so PG_ENT_SHIFT can be initialized on first SYSMMU probe to proper
 * value (0 or 4).
 */
static short PG_ENT_SHIFT = -1;
#define SYSMMU_PG_ENT_SHIFT 0
#define SYSMMU_V5_PG_ENT_SHIFT 4

#define sect_to_phys(ent) (((phys_addr_t) ent) << PG_ENT_SHIFT)
#define section_phys(sent) (sect_to_phys(*(sent)) & SECT_MASK)
#define section_offs(iova) (iova & (SECT_SIZE - 1))
#define lpage_phys(pent) (sect_to_phys(*(pent)) & LPAGE_MASK)
#define lpage_offs(iova) (iova & (LPAGE_SIZE - 1))
#define spage_phys(pent) (sect_to_phys(*(pent)) & SPAGE_MASK)
#define spage_offs(iova) (iova & (SPAGE_SIZE - 1))

#define NUM_LV1ENTRIES 4096
#define NUM_LV2ENTRIES (SECT_SIZE / SPAGE_SIZE)

static u32 lv1ent_offset(sysmmu_iova_t iova)
{
        return iova >> SECT_ORDER;
}

static u32 lv2ent_offset(sysmmu_iova_t iova)
{
        return (iova >> SPAGE_ORDER) & (NUM_LV2ENTRIES - 1);
}

#define LV1TABLE_SIZE (NUM_LV1ENTRIES * sizeof(sysmmu_pte_t))
#define LV2TABLE_SIZE (NUM_LV2ENTRIES * sizeof(sysmmu_pte_t))

#define SPAGES_PER_LPAGE (LPAGE_SIZE / SPAGE_SIZE)
#define lv2table_base(sent) (sect_to_phys(*(sent) & 0xFFFFFFC0))

#define mk_lv1ent_sect(pa) ((pa >> PG_ENT_SHIFT) | 2)
#define mk_lv1ent_page(pa) ((pa >> PG_ENT_SHIFT) | 1)
#define mk_lv2ent_lpage(pa) ((pa >> PG_ENT_SHIFT) | 1)
#define mk_lv2ent_spage(pa) ((pa >> PG_ENT_SHIFT) | 2)

#define CTRL_ENABLE     0x5
#define CTRL_BLOCK      0x7
#define CTRL_DISABLE    0x0

#define CFG_LRU         0x1
#define CFG_QOS(n)      ((n & 0xF) << 7)
#define CFG_ACGEN       (1 << 24) /* System MMU 3.3 only */
#define CFG_SYSSEL      (1 << 22) /* System MMU 3.2 only */
#define CFG_FLPDCACHE   (1 << 20) /* System MMU 3.2+ only */

/* common registers */
#define REG_MMU_CTRL            0x000
#define REG_MMU_CFG             0x004
#define REG_MMU_STATUS          0x008
#define REG_MMU_VERSION         0x034

#define MMU_MAJ_VER(val)        ((val) >> 7)
#define MMU_MIN_VER(val)        ((val) & 0x7F)
#define MMU_RAW_VER(reg)        (((reg) >> 21) & ((1 << 11) - 1)) /* 11 bits */

#define MAKE_MMU_VER(maj, min)  ((((maj) & 0xF) << 7) | ((min) & 0x7F))

/* v1.x - v3.x registers */
#define REG_MMU_FLUSH           0x00C
#define REG_MMU_FLUSH_ENTRY     0x010
#define REG_PT_BASE_ADDR        0x014
#define REG_INT_STATUS          0x018
#define REG_INT_CLEAR           0x01C

#define REG_PAGE_FAULT_ADDR     0x024
#define REG_AW_FAULT_ADDR       0x028
#define REG_AR_FAULT_ADDR       0x02C
#define REG_DEFAULT_SLAVE_ADDR  0x030

/* v5.x registers */
#define REG_V5_PT_BASE_PFN      0x00C
#define REG_V5_MMU_FLUSH_ALL    0x010
#define REG_V5_MMU_FLUSH_ENTRY  0x014
#define REG_V5_INT_STATUS       0x060
#define REG_V5_INT_CLEAR        0x064
#define REG_V5_FAULT_AR_VA      0x070
#define REG_V5_FAULT_AW_VA      0x080

#define has_sysmmu(dev)         (dev->archdata.iommu != NULL)

static struct device *dma_dev;
static struct kmem_cache *lv2table_kmem_cache;
static sysmmu_pte_t *zero_lv2_table;
#define ZERO_LV2LINK mk_lv1ent_page(virt_to_phys(zero_lv2_table))

static sysmmu_pte_t *section_entry(sysmmu_pte_t *pgtable, sysmmu_iova_t iova)
{
        return pgtable + lv1ent_offset(iova);
}

static sysmmu_pte_t *page_entry(sysmmu_pte_t *sent, sysmmu_iova_t iova)
{
        return (sysmmu_pte_t *)phys_to_virt(
                                lv2table_base(sent)) + lv2ent_offset(iova);
}

/*
 * IOMMU fault information register
 */
struct sysmmu_fault_info {
        unsigned int bit;       /* bit number in STATUS register */
        unsigned short addr_reg; /* register to read VA fault address */
        const char *name;       /* human readable fault name */
        unsigned int type;      /* fault type for report_iommu_fault */
};

static const struct sysmmu_fault_info sysmmu_faults[] = {
        { 0, REG_PAGE_FAULT_ADDR, "PAGE", IOMMU_FAULT_READ },
        { 1, REG_AR_FAULT_ADDR, "AR MULTI-HIT", IOMMU_FAULT_READ },
        { 2, REG_AW_FAULT_ADDR, "AW MULTI-HIT", IOMMU_FAULT_WRITE },
        { 3, REG_DEFAULT_SLAVE_ADDR, "BUS ERROR", IOMMU_FAULT_READ },
        { 4, REG_AR_FAULT_ADDR, "AR SECURITY PROTECTION", IOMMU_FAULT_READ },
        { 5, REG_AR_FAULT_ADDR, "AR ACCESS PROTECTION", IOMMU_FAULT_READ },
        { 6, REG_AW_FAULT_ADDR, "AW SECURITY PROTECTION", IOMMU_FAULT_WRITE },
        { 7, REG_AW_FAULT_ADDR, "AW ACCESS PROTECTION", IOMMU_FAULT_WRITE },
};

static const struct sysmmu_fault_info sysmmu_v5_faults[] = {
        { 0, REG_V5_FAULT_AR_VA, "AR PTW", IOMMU_FAULT_READ },
        { 1, REG_V5_FAULT_AR_VA, "AR PAGE", IOMMU_FAULT_READ },
        { 2, REG_V5_FAULT_AR_VA, "AR MULTI-HIT", IOMMU_FAULT_READ },
        { 3, REG_V5_FAULT_AR_VA, "AR ACCESS PROTECTION", IOMMU_FAULT_READ },
        { 4, REG_V5_FAULT_AR_VA, "AR SECURITY PROTECTION", IOMMU_FAULT_READ },
        { 16, REG_V5_FAULT_AW_VA, "AW PTW", IOMMU_FAULT_WRITE },
        { 17, REG_V5_FAULT_AW_VA, "AW PAGE", IOMMU_FAULT_WRITE },
        { 18, REG_V5_FAULT_AW_VA, "AW MULTI-HIT", IOMMU_FAULT_WRITE },
        { 19, REG_V5_FAULT_AW_VA, "AW ACCESS PROTECTION", IOMMU_FAULT_WRITE },
        { 20, REG_V5_FAULT_AW_VA, "AW SECURITY PROTECTION", IOMMU_FAULT_WRITE },
};

/*
 * This structure is attached to dev.archdata.iommu of the master device
 * on device add, contains a list of SYSMMU controllers defined by device tree,
 * which are bound to given master device. It is usually referenced by 'owner'
 * pointer.
*/
struct exynos_iommu_owner {
        struct list_head controllers;   /* list of sysmmu_drvdata.owner_node */
        struct iommu_domain *domain;    /* domain this device is attached */
};

/*
 * This structure exynos specific generalization of struct iommu_domain.
 * It contains list of SYSMMU controllers from all master devices, which has
 * been attached to this domain and page tables of IO address space defined by
 * it. It is usually referenced by 'domain' pointer.
 */
struct exynos_iommu_domain {
        struct list_head clients; /* list of sysmmu_drvdata.domain_node */
        sysmmu_pte_t *pgtable;  /* lv1 page table, 16KB */
        short *lv2entcnt;       /* free lv2 entry counter for each section */
        spinlock_t lock;        /* lock for modyfying list of clients */
        spinlock_t pgtablelock; /* lock for modifying page table @ pgtable */
        struct iommu_domain domain; /* generic domain data structure */
};

/*
 * This structure hold all data of a single SYSMMU controller, this includes
 * hw resources like registers and clocks, pointers and list nodes to connect
 * it to all other structures, internal state and parameters read from device
 * tree. It is usually referenced by 'data' pointer.
 */
struct sysmmu_drvdata {
        struct device *sysmmu;          /* SYSMMU controller device */
        struct device *master;          /* master device (owner) */
        void __iomem *sfrbase;          /* our registers */
        struct clk *clk;                /* SYSMMU's clock */
        struct clk *aclk;               /* SYSMMU's aclk clock */
        struct clk *pclk;               /* SYSMMU's pclk clock */
        struct clk *clk_master;         /* master's device clock */
        int activations;                /* number of calls to sysmmu_enable */
        spinlock_t lock;                /* lock for modyfying state */
        struct exynos_iommu_domain *domain; /* domain we belong to */
        struct list_head domain_node;   /* node for domain clients list */
        struct list_head owner_node;    /* node for owner controllers list */
        phys_addr_t pgtable;            /* assigned page table structure */
        unsigned int version;           /* our version */
};

static struct exynos_iommu_domain *to_exynos_domain(struct iommu_domain *dom)
{
        return container_of(dom, struct exynos_iommu_domain, domain);
}

static bool set_sysmmu_active(struct sysmmu_drvdata *data)
{
        /* return true if the System MMU was not active previously
           and it needs to be initialized */
        return ++data->activations == 1;
}

static bool set_sysmmu_inactive(struct sysmmu_drvdata *data)
{
        /* return true if the System MMU is needed to be disabled */
        BUG_ON(data->activations < 1);
        return --data->activations == 0;
}

static bool is_sysmmu_active(struct sysmmu_drvdata *data)
{
        return data->activations > 0;
}

static void sysmmu_unblock(struct sysmmu_drvdata *data)
{
        writel(CTRL_ENABLE, data->sfrbase + REG_MMU_CTRL);
}

static bool sysmmu_block(struct sysmmu_drvdata *data)
{
        int i = 120;

        writel(CTRL_BLOCK, data->sfrbase + REG_MMU_CTRL);
        while ((i > 0) && !(readl(data->sfrbase + REG_MMU_STATUS) & 1))
                --i;

        if (!(readl(data->sfrbase + REG_MMU_STATUS) & 1)) {
                sysmmu_unblock(data);
                return false;
        }

        return true;
}

static void __sysmmu_tlb_invalidate(struct sysmmu_drvdata *data)
{
        if (MMU_MAJ_VER(data->version) < 5)
                writel(0x1, data->sfrbase + REG_MMU_FLUSH);
        else
                writel(0x1, data->sfrbase + REG_V5_MMU_FLUSH_ALL);
}

static void __sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
                                sysmmu_iova_t iova, unsigned int num_inv)
{
        unsigned int i;

        for (i = 0; i < num_inv; i++) {
                if (MMU_MAJ_VER(data->version) < 5)
                        writel((iova & SPAGE_MASK) | 1,
                                     data->sfrbase + REG_MMU_FLUSH_ENTRY);
                else
                        writel((iova & SPAGE_MASK) | 1,
                                     data->sfrbase + REG_V5_MMU_FLUSH_ENTRY);
                iova += SPAGE_SIZE;
        }
}

static void __sysmmu_set_ptbase(struct sysmmu_drvdata *data, phys_addr_t pgd)
{
        if (MMU_MAJ_VER(data->version) < 5)
                writel(pgd, data->sfrbase + REG_PT_BASE_ADDR);
        else
                writel(pgd >> PAGE_SHIFT,
                             data->sfrbase + REG_V5_PT_BASE_PFN);

        __sysmmu_tlb_invalidate(data);
}

static void __sysmmu_enable_clocks(struct sysmmu_drvdata *data)
{
        BUG_ON(clk_prepare_enable(data->clk_master));
        BUG_ON(clk_prepare_enable(data->clk));
        BUG_ON(clk_prepare_enable(data->pclk));
        BUG_ON(clk_prepare_enable(data->aclk));
}

static void __sysmmu_disable_clocks(struct sysmmu_drvdata *data)
{
        clk_disable_unprepare(data->aclk);
        clk_disable_unprepare(data->pclk);
        clk_disable_unprepare(data->clk);
        clk_disable_unprepare(data->clk_master);
}

static void __sysmmu_get_version(struct sysmmu_drvdata *data)
{
        u32 ver;

        __sysmmu_enable_clocks(data);

        ver = readl(data->sfrbase + REG_MMU_VERSION);

        /* controllers on some SoCs don't report proper version */
        if (ver == 0x80000001u)
                data->version = MAKE_MMU_VER(1, 0);
        else
                data->version = MMU_RAW_VER(ver);

        dev_dbg(data->sysmmu, "hardware version: %d.%d\n",
                MMU_MAJ_VER(data->version), MMU_MIN_VER(data->version));

        __sysmmu_disable_clocks(data);
}

static void show_fault_information(struct sysmmu_drvdata *data,
                                   const struct sysmmu_fault_info *finfo,
                                   sysmmu_iova_t fault_addr)
{
        sysmmu_pte_t *ent;

        dev_err(data->sysmmu, "%s FAULT occurred at %#x (page table base: %pa)\n",
                finfo->name, fault_addr, &data->pgtable);
        ent = section_entry(phys_to_virt(data->pgtable), fault_addr);
        dev_err(data->sysmmu, "\tLv1 entry: %#x\n", *ent);
        if (lv1ent_page(ent)) {
                ent = page_entry(ent, fault_addr);
                dev_err(data->sysmmu, "\t Lv2 entry: %#x\n", *ent);
        }
}

static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
{
        /* SYSMMU is in blocked state when interrupt occurred. */
        struct sysmmu_drvdata *data = dev_id;
        const struct sysmmu_fault_info *finfo;
        unsigned int i, n, itype;
        sysmmu_iova_t fault_addr = -1;
        unsigned short reg_status, reg_clear;
        int ret = -ENOSYS;

        WARN_ON(!is_sysmmu_active(data));

        if (MMU_MAJ_VER(data->version) < 5) {
                reg_status = REG_INT_STATUS;
                reg_clear = REG_INT_CLEAR;
                finfo = sysmmu_faults;
                n = ARRAY_SIZE(sysmmu_faults);
        } else {
                reg_status = REG_V5_INT_STATUS;
                reg_clear = REG_V5_INT_CLEAR;
                finfo = sysmmu_v5_faults;
                n = ARRAY_SIZE(sysmmu_v5_faults);
        }

        spin_lock(&data->lock);

        clk_enable(data->clk_master);

        itype = __ffs(readl(data->sfrbase + reg_status));
        for (i = 0; i < n; i++, finfo++)
                if (finfo->bit == itype)
                        break;
        /* unknown/unsupported fault */
        BUG_ON(i == n);

        /* print debug message */
        fault_addr = readl(data->sfrbase + finfo->addr_reg);
        show_fault_information(data, finfo, fault_addr);

        if (data->domain)
                ret = report_iommu_fault(&data->domain->domain,
                                        data->master, fault_addr, finfo->type);
        /* fault is not recovered by fault handler */
        BUG_ON(ret != 0);

        writel(1 << itype, data->sfrbase + reg_clear);

        sysmmu_unblock(data);

        clk_disable(data->clk_master);

        spin_unlock(&data->lock);

        return IRQ_HANDLED;
}

static void __sysmmu_disable_nocount(struct sysmmu_drvdata *data)
{
        clk_enable(data->clk_master);

        writel(CTRL_DISABLE, data->sfrbase + REG_MMU_CTRL);
        writel(0, data->sfrbase + REG_MMU_CFG);

        __sysmmu_disable_clocks(data);
}

static bool __sysmmu_disable(struct sysmmu_drvdata *data)
{
        bool disabled;
        unsigned long flags;

        spin_lock_irqsave(&data->lock, flags);

        disabled = set_sysmmu_inactive(data);

        if (disabled) {
                data->pgtable = 0;
                data->domain = NULL;

                __sysmmu_disable_nocount(data);

                dev_dbg(data->sysmmu, "Disabled\n");
        } else  {
                dev_dbg(data->sysmmu, "%d times left to disable\n",
                                        data->activations);
        }

        spin_unlock_irqrestore(&data->lock, flags);

        return disabled;
}

static void __sysmmu_init_config(struct sysmmu_drvdata *data)
{
        unsigned int cfg;

        if (data->version <= MAKE_MMU_VER(3, 1))
                cfg = CFG_LRU | CFG_QOS(15);
        else if (data->version <= MAKE_MMU_VER(3, 2))
                cfg = CFG_LRU | CFG_QOS(15) | CFG_FLPDCACHE | CFG_SYSSEL;
        else
                cfg = CFG_QOS(15) | CFG_FLPDCACHE | CFG_ACGEN;

        writel(cfg, data->sfrbase + REG_MMU_CFG);
}

static void __sysmmu_enable_nocount(struct sysmmu_drvdata *data)
{
        __sysmmu_enable_clocks(data);

        writel(CTRL_BLOCK, data->sfrbase + REG_MMU_CTRL);

        __sysmmu_init_config(data);

        __sysmmu_set_ptbase(data, data->pgtable);

        writel(CTRL_ENABLE, data->sfrbase + REG_MMU_CTRL);

        /*
         * SYSMMU driver keeps master's clock enabled only for the short
         * time, while accessing the registers. For performing address
         * translation during DMA transaction it relies on the client
         * driver to enable it.
         */
        clk_disable(data->clk_master);
}

static int __sysmmu_enable(struct sysmmu_drvdata *data, phys_addr_t pgtable,
                           struct exynos_iommu_domain *domain)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&data->lock, flags);
        if (set_sysmmu_active(data)) {
                data->pgtable = pgtable;
                data->domain = domain;

                __sysmmu_enable_nocount(data);

                dev_dbg(data->sysmmu, "Enabled\n");
        } else {
                ret = (pgtable == data->pgtable) ? 1 : -EBUSY;

                dev_dbg(data->sysmmu, "already enabled\n");
        }

        if (WARN_ON(ret < 0))
                set_sysmmu_inactive(data); /* decrement count */

        spin_unlock_irqrestore(&data->lock, flags);

        return ret;
}

static void sysmmu_tlb_invalidate_flpdcache(struct sysmmu_drvdata *data,
                                            sysmmu_iova_t iova)
{
        unsigned long flags;


        spin_lock_irqsave(&data->lock, flags);
        if (is_sysmmu_active(data) && data->version >= MAKE_MMU_VER(3, 3)) {
                clk_enable(data->clk_master);
                __sysmmu_tlb_invalidate_entry(data, iova, 1);
                clk_disable(data->clk_master);
        }
        spin_unlock_irqrestore(&data->lock, flags);

}

static void sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
                                        sysmmu_iova_t iova, size_t size)
{
        unsigned long flags;

        spin_lock_irqsave(&data->lock, flags);
        if (is_sysmmu_active(data)) {
                unsigned int num_inv = 1;

                clk_enable(data->clk_master);

                /*
                 * L2TLB invalidation required
                 * 4KB page: 1 invalidation
                 * 64KB page: 16 invalidations
                 * 1MB page: 64 invalidations
                 * because it is set-associative TLB
                 * with 8-way and 64 sets.
                 * 1MB page can be cached in one of all sets.
                 * 64KB page can be one of 16 consecutive sets.
                 */
                if (MMU_MAJ_VER(data->version) == 2)
                        num_inv = min_t(unsigned int, size / PAGE_SIZE, 64);

                if (sysmmu_block(data)) {
                        __sysmmu_tlb_invalidate_entry(data, iova, num_inv);
                        sysmmu_unblock(data);
                }
                clk_disable(data->clk_master);
        } else {
                dev_dbg(data->master,
                        "disabled. Skipping TLB invalidation @ %#x\n", iova);
        }
        spin_unlock_irqrestore(&data->lock, flags);
}

static struct iommu_ops exynos_iommu_ops;

static int __init exynos_sysmmu_probe(struct platform_device *pdev)
{
        int irq, ret;
        struct device *dev = &pdev->dev;
        struct sysmmu_drvdata *data;
        struct resource *res;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        data->sfrbase = devm_ioremap_resource(dev, res);
        if (IS_ERR(data->sfrbase))
                return PTR_ERR(data->sfrbase);

        irq = platform_get_irq(pdev, 0);
        if (irq <= 0) {
                dev_err(dev, "Unable to find IRQ resource\n");
                return irq;
        }

        ret = devm_request_irq(dev, irq, exynos_sysmmu_irq, 0,
                                dev_name(dev), data);
        if (ret) {
                dev_err(dev, "Unabled to register handler of irq %d\n", irq);
                return ret;
        }

        data->clk = devm_clk_get(dev, "sysmmu");
        if (PTR_ERR(data->clk) == -ENOENT)
                data->clk = NULL;
        else if (IS_ERR(data->clk))
                return PTR_ERR(data->clk);

        data->aclk = devm_clk_get(dev, "aclk");
        if (PTR_ERR(data->aclk) == -ENOENT)
                data->aclk = NULL;
        else if (IS_ERR(data->aclk))
                return PTR_ERR(data->aclk);

        data->pclk = devm_clk_get(dev, "pclk");
        if (PTR_ERR(data->pclk) == -ENOENT)
                data->pclk = NULL;
        else if (IS_ERR(data->pclk))
                return PTR_ERR(data->pclk);

        if (!data->clk && (!data->aclk || !data->pclk)) {
                dev_err(dev, "Failed to get device clock(s)!\n");
                return -ENOSYS;
        }

        data->clk_master = devm_clk_get(dev, "master");
        if (PTR_ERR(data->clk_master) == -ENOENT)
                data->clk_master = NULL;
        else if (IS_ERR(data->clk_master))
                return PTR_ERR(data->clk_master);

        data->sysmmu = dev;
        spin_lock_init(&data->lock);

        platform_set_drvdata(pdev, data);

        __sysmmu_get_version(data);
        if (PG_ENT_SHIFT < 0) {
                if (MMU_MAJ_VER(data->version) < 5)
                        PG_ENT_SHIFT = SYSMMU_PG_ENT_SHIFT;
                else
                        PG_ENT_SHIFT = SYSMMU_V5_PG_ENT_SHIFT;
        }

        pm_runtime_enable(dev);

        of_iommu_set_ops(dev->of_node, &exynos_iommu_ops);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int exynos_sysmmu_suspend(struct device *dev)
{
        struct sysmmu_drvdata *data = dev_get_drvdata(dev);

        dev_dbg(dev, "suspend\n");
        if (is_sysmmu_active(data)) {
                __sysmmu_disable_nocount(data);
                pm_runtime_put(dev);
        }
        return 0;
}

static int exynos_sysmmu_resume(struct device *dev)
{
        struct sysmmu_drvdata *data = dev_get_drvdata(dev);

        dev_dbg(dev, "resume\n");
        if (is_sysmmu_active(data)) {
                pm_runtime_get_sync(dev);
                __sysmmu_enable_nocount(data);
        }
        return 0;
}
#endif

static const struct dev_pm_ops sysmmu_pm_ops = {
        SET_LATE_SYSTEM_SLEEP_PM_OPS(exynos_sysmmu_suspend, exynos_sysmmu_resume)
};

static const struct of_device_id sysmmu_of_match[] __initconst = {
        { .compatible   = "samsung,exynos-sysmmu", },
        { },
};

static struct platform_driver exynos_sysmmu_driver __refdata = {
        .probe  = exynos_sysmmu_probe,
        .driver = {
                .name           = "exynos-sysmmu",
                .of_match_table = sysmmu_of_match,
                .pm             = &sysmmu_pm_ops,
                .suppress_bind_attrs = true,
        }
};

static inline void update_pte(sysmmu_pte_t *ent, sysmmu_pte_t val)
{
        dma_sync_single_for_cpu(dma_dev, virt_to_phys(ent), sizeof(*ent),
                                DMA_TO_DEVICE);
        *ent = cpu_to_le32(val);
        dma_sync_single_for_device(dma_dev, virt_to_phys(ent), sizeof(*ent),
                                   DMA_TO_DEVICE);
}

static struct iommu_domain *exynos_iommu_domain_alloc(unsigned type)
{
        struct exynos_iommu_domain *domain;
        dma_addr_t handle;
        int i;

        /* Check if correct PTE offsets are initialized */
        BUG_ON(PG_ENT_SHIFT < 0 || !dma_dev);

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

        if (type == IOMMU_DOMAIN_DMA) {
                if (iommu_get_dma_cookie(&domain->domain) != 0)
                        goto err_pgtable;
        } else if (type != IOMMU_DOMAIN_UNMANAGED) {
                goto err_pgtable;
        }

        domain->pgtable = (sysmmu_pte_t *)__get_free_pages(GFP_KERNEL, 2);
        if (!domain->pgtable)
                goto err_dma_cookie;

        domain->lv2entcnt = (short *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
        if (!domain->lv2entcnt)
                goto err_counter;

        /* Workaround for System MMU v3.3 to prevent caching 1MiB mapping */
        for (i = 0; i < NUM_LV1ENTRIES; i += 8) {
                domain->pgtable[i + 0] = ZERO_LV2LINK;
                domain->pgtable[i + 1] = ZERO_LV2LINK;
                domain->pgtable[i + 2] = ZERO_LV2LINK;
                domain->pgtable[i + 3] = ZERO_LV2LINK;
                domain->pgtable[i + 4] = ZERO_LV2LINK;
                domain->pgtable[i + 5] = ZERO_LV2LINK;
                domain->pgtable[i + 6] = ZERO_LV2LINK;
                domain->pgtable[i + 7] = ZERO_LV2LINK;
        }

        handle = dma_map_single(dma_dev, domain->pgtable, LV1TABLE_SIZE,
                                DMA_TO_DEVICE);
        /* For mapping page table entries we rely on dma == phys */
        BUG_ON(handle != virt_to_phys(domain->pgtable));

        spin_lock_init(&domain->lock);
        spin_lock_init(&domain->pgtablelock);
        INIT_LIST_HEAD(&domain->clients);

        domain->domain.geometry.aperture_start = 0;
        domain->domain.geometry.aperture_end   = ~0UL;
        domain->domain.geometry.force_aperture = true;

        return &domain->domain;

err_counter:
        free_pages((unsigned long)domain->pgtable, 2);
err_dma_cookie:
        if (type == IOMMU_DOMAIN_DMA)
                iommu_put_dma_cookie(&domain->domain);
err_pgtable:
        kfree(domain);
        return NULL;
}

static void exynos_iommu_domain_free(struct iommu_domain *iommu_domain)
{
        struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
        struct sysmmu_drvdata *data, *next;
        unsigned long flags;
        int i;

        WARN_ON(!list_empty(&domain->clients));

        spin_lock_irqsave(&domain->lock, flags);

        list_for_each_entry_safe(data, next, &domain->clients, domain_node) {
                if (__sysmmu_disable(data))
                        data->master = NULL;
                list_del_init(&data->domain_node);
        }

        spin_unlock_irqrestore(&domain->lock, flags);

        if (iommu_domain->type == IOMMU_DOMAIN_DMA)
                iommu_put_dma_cookie(iommu_domain);

        dma_unmap_single(dma_dev, virt_to_phys(domain->pgtable), LV1TABLE_SIZE,
                         DMA_TO_DEVICE);

        for (i = 0; i < NUM_LV1ENTRIES; i++)
                if (lv1ent_page(domain->pgtable + i)) {
                        phys_addr_t base = lv2table_base(domain->pgtable + i);

                        dma_unmap_single(dma_dev, base, LV2TABLE_SIZE,
                                         DMA_TO_DEVICE);
                        kmem_cache_free(lv2table_kmem_cache,
                                        phys_to_virt(base));
                }

        free_pages((unsigned long)domain->pgtable, 2);
        free_pages((unsigned long)domain->lv2entcnt, 1);
        kfree(domain);
}

static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
                                    struct device *dev)
{
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
        phys_addr_t pagetable = virt_to_phys(domain->pgtable);
        struct sysmmu_drvdata *data, *next;
        unsigned long flags;
        bool found = false;

        if (!has_sysmmu(dev) || owner->domain != iommu_domain)
                return;

        spin_lock_irqsave(&domain->lock, flags);
        list_for_each_entry_safe(data, next, &domain->clients, domain_node) {
                if (data->master == dev) {
                        if (__sysmmu_disable(data)) {
                                data->master = NULL;
                                list_del_init(&data->domain_node);
                        }
                        pm_runtime_put(data->sysmmu);
                        found = true;
                }
        }
        spin_unlock_irqrestore(&domain->lock, flags);

        owner->domain = NULL;

        if (found)
                dev_dbg(dev, "%s: Detached IOMMU with pgtable %pa\n",
                                        __func__, &pagetable);
        else
                dev_err(dev, "%s: No IOMMU is attached\n", __func__);
}

static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
                                   struct device *dev)
{
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
        struct sysmmu_drvdata *data;
        phys_addr_t pagetable = virt_to_phys(domain->pgtable);
        unsigned long flags;
        int ret = -ENODEV;

        if (!has_sysmmu(dev))
                return -ENODEV;

        if (owner->domain)
                exynos_iommu_detach_device(owner->domain, dev);

        list_for_each_entry(data, &owner->controllers, owner_node) {
                pm_runtime_get_sync(data->sysmmu);
                ret = __sysmmu_enable(data, pagetable, domain);
                if (ret >= 0) {
                        data->master = dev;

                        spin_lock_irqsave(&domain->lock, flags);
                        list_add_tail(&data->domain_node, &domain->clients);
                        spin_unlock_irqrestore(&domain->lock, flags);
                }
        }

        if (ret < 0) {
                dev_err(dev, "%s: Failed to attach IOMMU with pgtable %pa\n",
                                        __func__, &pagetable);
                return ret;
        }

        owner->domain = iommu_domain;
        dev_dbg(dev, "%s: Attached IOMMU with pgtable %pa %s\n",
                __func__, &pagetable, (ret == 0) ? "" : ", again");

        return ret;
}

static sysmmu_pte_t *alloc_lv2entry(struct exynos_iommu_domain *domain,
                sysmmu_pte_t *sent, sysmmu_iova_t iova, short *pgcounter)
{
        if (lv1ent_section(sent)) {
                WARN(1, "Trying mapping on %#08x mapped with 1MiB page", iova);
                return ERR_PTR(-EADDRINUSE);
        }

        if (lv1ent_fault(sent)) {
                sysmmu_pte_t *pent;
                bool need_flush_flpd_cache = lv1ent_zero(sent);

                pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
                BUG_ON((uintptr_t)pent & (LV2TABLE_SIZE - 1));
                if (!pent)
                        return ERR_PTR(-ENOMEM);

                update_pte(sent, mk_lv1ent_page(virt_to_phys(pent)));
                kmemleak_ignore(pent);
                *pgcounter = NUM_LV2ENTRIES;
                dma_map_single(dma_dev, pent, LV2TABLE_SIZE, DMA_TO_DEVICE);

                /*
                 * If pre-fetched SLPD is a faulty SLPD in zero_l2_table,
                 * FLPD cache may cache the address of zero_l2_table. This
                 * function replaces the zero_l2_table with new L2 page table
                 * to write valid mappings.
                 * Accessing the valid area may cause page fault since FLPD
                 * cache may still cache zero_l2_table for the valid area
                 * instead of new L2 page table that has the mapping
                 * information of the valid area.
                 * Thus any replacement of zero_l2_table with other valid L2
                 * page table must involve FLPD cache invalidation for System
                 * MMU v3.3.
                 * FLPD cache invalidation is performed with TLB invalidation
                 * by VPN without blocking. It is safe to invalidate TLB without
                 * blocking because the target address of TLB invalidation is
                 * not currently mapped.
                 */
                if (need_flush_flpd_cache) {
                        struct sysmmu_drvdata *data;

                        spin_lock(&domain->lock);
                        list_for_each_entry(data, &domain->clients, domain_node)
                                sysmmu_tlb_invalidate_flpdcache(data, iova);
                        spin_unlock(&domain->lock);
                }
        }

        return page_entry(sent, iova);
}

static int lv1set_section(struct exynos_iommu_domain *domain,
                          sysmmu_pte_t *sent, sysmmu_iova_t iova,
                          phys_addr_t paddr, short *pgcnt)
{
        if (lv1ent_section(sent)) {
                WARN(1, "Trying mapping on 1MiB@%#08x that is mapped",
                        iova);
                return -EADDRINUSE;
        }

        if (lv1ent_page(sent)) {
                if (*pgcnt != NUM_LV2ENTRIES) {
                        WARN(1, "Trying mapping on 1MiB@%#08x that is mapped",
                                iova);
                        return -EADDRINUSE;
                }

                kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
                *pgcnt = 0;
        }

        update_pte(sent, mk_lv1ent_sect(paddr));

        spin_lock(&domain->lock);
        if (lv1ent_page_zero(sent)) {
                struct sysmmu_drvdata *data;
                /*
                 * Flushing FLPD cache in System MMU v3.3 that may cache a FLPD
                 * entry by speculative prefetch of SLPD which has no mapping.
                 */
                list_for_each_entry(data, &domain->clients, domain_node)
                        sysmmu_tlb_invalidate_flpdcache(data, iova);
        }
        spin_unlock(&domain->lock);

        return 0;
}

static int lv2set_page(sysmmu_pte_t *pent, phys_addr_t paddr, size_t size,
                                                                short *pgcnt)
{
        if (size == SPAGE_SIZE) {
                if (WARN_ON(!lv2ent_fault(pent)))
                        return -EADDRINUSE;

                update_pte(pent, mk_lv2ent_spage(paddr));
                *pgcnt -= 1;
        } else { /* size == LPAGE_SIZE */
                int i;
                dma_addr_t pent_base = virt_to_phys(pent);

                dma_sync_single_for_cpu(dma_dev, pent_base,
                                        sizeof(*pent) * SPAGES_PER_LPAGE,
                                        DMA_TO_DEVICE);
                for (i = 0; i < SPAGES_PER_LPAGE; i++, pent++) {
                        if (WARN_ON(!lv2ent_fault(pent))) {
                                if (i > 0)
                                        memset(pent - i, 0, sizeof(*pent) * i);
                                return -EADDRINUSE;
                        }

                        *pent = mk_lv2ent_lpage(paddr);
                }
                dma_sync_single_for_device(dma_dev, pent_base,
                                           sizeof(*pent) * SPAGES_PER_LPAGE,
                                           DMA_TO_DEVICE);
                *pgcnt -= SPAGES_PER_LPAGE;
        }

        return 0;
}

/*
 * *CAUTION* to the I/O virtual memory managers that support exynos-iommu:
 *
 * System MMU v3.x has advanced logic to improve address translation
 * performance with caching more page table entries by a page table walk.
 * However, the logic has a bug that while caching faulty page table entries,
 * System MMU reports page fault if the cached fault entry is hit even though
 * the fault entry is updated to a valid entry after the entry is cached.
 * To prevent caching faulty page table entries which may be updated to valid
 * entries later, the virtual memory manager should care about the workaround
 * for the problem. The following describes the workaround.
 *
 * Any two consecutive I/O virtual address regions must have a hole of 128KiB
 * at maximum to prevent misbehavior of System MMU 3.x (workaround for h/w bug).
 *
 * Precisely, any start address of I/O virtual region must be aligned with
 * the following sizes for System MMU v3.1 and v3.2.
 * System MMU v3.1: 128KiB
 * System MMU v3.2: 256KiB
 *
 * Because System MMU v3.3 caches page table entries more aggressively, it needs
 * more workarounds.
 * - Any two consecutive I/O virtual regions must have a hole of size larger
 *   than or equal to 128KiB.
 * - Start address of an I/O virtual region must be aligned by 128KiB.
 */
static int exynos_iommu_map(struct iommu_domain *iommu_domain,
                            unsigned long l_iova, phys_addr_t paddr, size_t size,
                            int prot)
{
        struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
        sysmmu_pte_t *entry;
        sysmmu_iova_t iova = (sysmmu_iova_t)l_iova;
        unsigned long flags;
        int ret = -ENOMEM;

        BUG_ON(domain->pgtable == NULL);

        spin_lock_irqsave(&domain->pgtablelock, flags);

        entry = section_entry(domain->pgtable, iova);

        if (size == SECT_SIZE) {
                ret = lv1set_section(domain, entry, iova, paddr,
                                     &domain->lv2entcnt[lv1ent_offset(iova)]);
        } else {
                sysmmu_pte_t *pent;

                pent = alloc_lv2entry(domain, entry, iova,
                                      &domain->lv2entcnt[lv1ent_offset(iova)]);

                if (IS_ERR(pent))
                        ret = PTR_ERR(pent);
                else
                        ret = lv2set_page(pent, paddr, size,
                                       &domain->lv2entcnt[lv1ent_offset(iova)]);
        }

        if (ret)
                pr_err("%s: Failed(%d) to map %#zx bytes @ %#x\n",
                        __func__, ret, size, iova);

        spin_unlock_irqrestore(&domain->pgtablelock, flags);

        return ret;
}

static void exynos_iommu_tlb_invalidate_entry(struct exynos_iommu_domain *domain,
                                              sysmmu_iova_t iova, size_t size)
{
        struct sysmmu_drvdata *data;
        unsigned long flags;

        spin_lock_irqsave(&domain->lock, flags);

        list_for_each_entry(data, &domain->clients, domain_node)
                sysmmu_tlb_invalidate_entry(data, iova, size);

        spin_unlock_irqrestore(&domain->lock, flags);
}

static size_t exynos_iommu_unmap(struct iommu_domain *iommu_domain,
                                 unsigned long l_iova, size_t size)
{
        struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
        sysmmu_iova_t iova = (sysmmu_iova_t)l_iova;
        sysmmu_pte_t *ent;
        size_t err_pgsize;
        unsigned long flags;

        BUG_ON(domain->pgtable == NULL);

        spin_lock_irqsave(&domain->pgtablelock, flags);

        ent = section_entry(domain->pgtable, iova);

        if (lv1ent_section(ent)) {
                if (WARN_ON(size < SECT_SIZE)) {
                        err_pgsize = SECT_SIZE;
                        goto err;
                }

                /* workaround for h/w bug in System MMU v3.3 */
                update_pte(ent, ZERO_LV2LINK);
                size = SECT_SIZE;
                goto done;
        }

        if (unlikely(lv1ent_fault(ent))) {
                if (size > SECT_SIZE)
                        size = SECT_SIZE;
                goto done;
        }

        /* lv1ent_page(sent) == true here */

        ent = page_entry(ent, iova);

        if (unlikely(lv2ent_fault(ent))) {
                size = SPAGE_SIZE;
                goto done;
        }

        if (lv2ent_small(ent)) {
                update_pte(ent, 0);
                size = SPAGE_SIZE;
                domain->lv2entcnt[lv1ent_offset(iova)] += 1;
                goto done;
        }

        /* lv1ent_large(ent) == true here */
        if (WARN_ON(size < LPAGE_SIZE)) {
                err_pgsize = LPAGE_SIZE;
                goto err;
        }

        dma_sync_single_for_cpu(dma_dev, virt_to_phys(ent),
                                sizeof(*ent) * SPAGES_PER_LPAGE,
                                DMA_TO_DEVICE);
        memset(ent, 0, sizeof(*ent) * SPAGES_PER_LPAGE);
        dma_sync_single_for_device(dma_dev, virt_to_phys(ent),
                                   sizeof(*ent) * SPAGES_PER_LPAGE,
                                   DMA_TO_DEVICE);
        size = LPAGE_SIZE;
        domain->lv2entcnt[lv1ent_offset(iova)] += SPAGES_PER_LPAGE;
done:
        spin_unlock_irqrestore(&domain->pgtablelock, flags);

        exynos_iommu_tlb_invalidate_entry(domain, iova, size);

        return size;
err:
        spin_unlock_irqrestore(&domain->pgtablelock, flags);

        pr_err("%s: Failed: size(%#zx) @ %#x is smaller than page size %#zx\n",
                __func__, size, iova, err_pgsize);

        return 0;
}

static phys_addr_t exynos_iommu_iova_to_phys(struct iommu_domain *iommu_domain,
                                          dma_addr_t iova)
{
        struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
        sysmmu_pte_t *entry;
        unsigned long flags;
        phys_addr_t phys = 0;

        spin_lock_irqsave(&domain->pgtablelock, flags);

        entry = section_entry(domain->pgtable, iova);

        if (lv1ent_section(entry)) {
                phys = section_phys(entry) + section_offs(iova);
        } else if (lv1ent_page(entry)) {
                entry = page_entry(entry, iova);

                if (lv2ent_large(entry))
                        phys = lpage_phys(entry) + lpage_offs(iova);
                else if (lv2ent_small(entry))
                        phys = spage_phys(entry) + spage_offs(iova);
        }

        spin_unlock_irqrestore(&domain->pgtablelock, flags);

        return phys;
}

static struct iommu_group *get_device_iommu_group(struct device *dev)
{
        struct iommu_group *group;

        group = iommu_group_get(dev);
        if (!group)
                group = iommu_group_alloc();

        return group;
}

static int exynos_iommu_add_device(struct device *dev)
{
        struct iommu_group *group;

        if (!has_sysmmu(dev))
                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 exynos_iommu_remove_device(struct device *dev)
{
        if (!has_sysmmu(dev))
                return;

        iommu_group_remove_device(dev);
}

static int exynos_iommu_of_xlate(struct device *dev,
                                 struct of_phandle_args *spec)
{
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        struct platform_device *sysmmu = of_find_device_by_node(spec->np);
        struct sysmmu_drvdata *data;

        if (!sysmmu)
                return -ENODEV;

        data = platform_get_drvdata(sysmmu);
        if (!data)
                return -ENODEV;

        if (!owner) {
                owner = kzalloc(sizeof(*owner), GFP_KERNEL);
                if (!owner)
                        return -ENOMEM;

                INIT_LIST_HEAD(&owner->controllers);
                dev->archdata.iommu = owner;
        }

        list_add_tail(&data->owner_node, &owner->controllers);
        return 0;
}

static struct iommu_ops exynos_iommu_ops = {
        .domain_alloc = exynos_iommu_domain_alloc,
        .domain_free = exynos_iommu_domain_free,
        .attach_dev = exynos_iommu_attach_device,
        .detach_dev = exynos_iommu_detach_device,
        .map = exynos_iommu_map,
        .unmap = exynos_iommu_unmap,
        .map_sg = default_iommu_map_sg,
        .iova_to_phys = exynos_iommu_iova_to_phys,
        .device_group = get_device_iommu_group,
        .add_device = exynos_iommu_add_device,
        .remove_device = exynos_iommu_remove_device,
        .pgsize_bitmap = SECT_SIZE | LPAGE_SIZE | SPAGE_SIZE,
        .of_xlate = exynos_iommu_of_xlate,
};

static bool init_done;

static int __init exynos_iommu_init(void)
{
        int ret;

        lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
                                LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
        if (!lv2table_kmem_cache) {
                pr_err("%s: Failed to create kmem cache\n", __func__);
                return -ENOMEM;
        }

        ret = platform_driver_register(&exynos_sysmmu_driver);
        if (ret) {
                pr_err("%s: Failed to register driver\n", __func__);
                goto err_reg_driver;
        }

        zero_lv2_table = kmem_cache_zalloc(lv2table_kmem_cache, GFP_KERNEL);
        if (zero_lv2_table == NULL) {
                pr_err("%s: Failed to allocate zero level2 page table\n",
                        __func__);
                ret = -ENOMEM;
                goto err_zero_lv2;
        }

        ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
        if (ret) {
                pr_err("%s: Failed to register exynos-iommu driver.\n",
                                                                __func__);
                goto err_set_iommu;
        }

        init_done = true;

        return 0;
err_set_iommu:
        kmem_cache_free(lv2table_kmem_cache, zero_lv2_table);
err_zero_lv2:
        platform_driver_unregister(&exynos_sysmmu_driver);
err_reg_driver:
        kmem_cache_destroy(lv2table_kmem_cache);
        return ret;
}

static int __init exynos_iommu_of_setup(struct device_node *np)
{
        struct platform_device *pdev;

        if (!init_done)
                exynos_iommu_init();

        pdev = of_platform_device_create(np, NULL, platform_bus_type.dev_root);
        if (IS_ERR(pdev))
                return PTR_ERR(pdev);

        /*
         * use the first registered sysmmu device for performing
         * dma mapping operations on iommu page tables (cpu cache flush)
         */
        if (!dma_dev)
                dma_dev = &pdev->dev;

        return 0;
}

IOMMU_OF_DECLARE(exynos_iommu_of, "samsung,exynos-sysmmu",
                 exynos_iommu_of_setup);