/* linux/drivers/iommu/exynos_iommu.c
 *
 * Copyright (c) 2011 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/io.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/iommu.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/memblock.h>
#include <linux/export.h>

#include <asm/cacheflush.h>
#include <asm/pgtable.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)

static u32 sysmmu_page_offset(sysmmu_iova_t iova, u32 size)
{
        return iova & (size - 1);
}

#define section_phys(sent) (*(sent) & SECT_MASK)
#define section_offs(iova) sysmmu_page_offset((iova), SECT_SIZE)
#define lpage_phys(pent) (*(pent) & LPAGE_MASK)
#define lpage_offs(iova) sysmmu_page_offset((iova), LPAGE_SIZE)
#define spage_phys(pent) (*(pent) & SPAGE_MASK)
#define spage_offs(iova) sysmmu_page_offset((iova), SPAGE_SIZE)

#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 LV2TABLE_SIZE (NUM_LV2ENTRIES * sizeof(sysmmu_pte_t))

#define SPAGES_PER_LPAGE (LPAGE_SIZE / SPAGE_SIZE)

#define lv2table_base(sent) (*(sent) & 0xFFFFFC00)

#define mk_lv1ent_sect(pa) ((pa) | 2)
#define mk_lv1ent_page(pa) ((pa) | 1)
#define mk_lv2ent_lpage(pa) ((pa) | 1)
#define mk_lv2ent_spage(pa) ((pa) | 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_MASK        0x0150FFFF /* Selecting bit 0-15, 20, 22 and 24 */
#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 */

#define REG_MMU_CTRL            0x000
#define REG_MMU_CFG             0x004
#define REG_MMU_STATUS          0x008
#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

#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))

#define REG_PB0_SADDR           0x04C
#define REG_PB0_EADDR           0x050
#define REG_PB1_SADDR           0x054
#define REG_PB1_EADDR           0x058

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

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);
}

enum exynos_sysmmu_inttype {
        SYSMMU_PAGEFAULT,
        SYSMMU_AR_MULTIHIT,
        SYSMMU_AW_MULTIHIT,
        SYSMMU_BUSERROR,
        SYSMMU_AR_SECURITY,
        SYSMMU_AR_ACCESS,
        SYSMMU_AW_SECURITY,
        SYSMMU_AW_PROTECTION, /* 7 */
        SYSMMU_FAULT_UNKNOWN,
        SYSMMU_FAULTS_NUM
};

static unsigned short fault_reg_offset[SYSMMU_FAULTS_NUM] = {
        REG_PAGE_FAULT_ADDR,
        REG_AR_FAULT_ADDR,
        REG_AW_FAULT_ADDR,
        REG_DEFAULT_SLAVE_ADDR,
        REG_AR_FAULT_ADDR,
        REG_AR_FAULT_ADDR,
        REG_AW_FAULT_ADDR,
        REG_AW_FAULT_ADDR
};

static char *sysmmu_fault_name[SYSMMU_FAULTS_NUM] = {
        "PAGE FAULT",
        "AR MULTI-HIT FAULT",
        "AW MULTI-HIT FAULT",
        "BUS ERROR",
        "AR SECURITY PROTECTION FAULT",
        "AR ACCESS PROTECTION FAULT",
        "AW SECURITY PROTECTION FAULT",
        "AW ACCESS PROTECTION FAULT",
        "UNKNOWN FAULT"
};

/* attached to dev.archdata.iommu of the master device */
struct exynos_iommu_owner {
        struct list_head client; /* entry of exynos_iommu_domain.clients */
        struct device *dev;
        struct device *sysmmu;
        struct iommu_domain *domain;
        void *vmm_data;         /* IO virtual memory manager's data */
        spinlock_t lock;        /* Lock to preserve consistency of System MMU */
};

struct exynos_iommu_domain {
        struct list_head clients; /* list of sysmmu_drvdata.node */
        sysmmu_pte_t *pgtable; /* lv1 page table, 16KB */
        short *lv2entcnt; /* free lv2 entry counter for each section */
        spinlock_t lock; /* lock for this structure */
        spinlock_t pgtablelock; /* lock for modifying page table @ pgtable */
        struct iommu_domain domain; /* generic domain data structure */
};

struct sysmmu_drvdata {
        struct device *sysmmu;  /* System MMU's device descriptor */
        struct device *master;  /* Owner of system MMU */
        void __iomem *sfrbase;
        struct clk *clk;
        struct clk *clk_master;
        int activations;
        spinlock_t lock;
        struct iommu_domain *domain;
        phys_addr_t pgtable;
};

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(void __iomem *sfrbase)
{
        __raw_writel(CTRL_ENABLE, sfrbase + REG_MMU_CTRL);
}

static unsigned int __raw_sysmmu_version(struct sysmmu_drvdata *data)
{
        return MMU_RAW_VER(__raw_readl(data->sfrbase + REG_MMU_VERSION));
}

static bool sysmmu_block(void __iomem *sfrbase)
{
        int i = 120;

        __raw_writel(CTRL_BLOCK, sfrbase + REG_MMU_CTRL);
        while ((i > 0) && !(__raw_readl(sfrbase + REG_MMU_STATUS) & 1))
                --i;

        if (!(__raw_readl(sfrbase + REG_MMU_STATUS) & 1)) {
                sysmmu_unblock(sfrbase);
                return false;
        }

        return true;
}

static void __sysmmu_tlb_invalidate(void __iomem *sfrbase)
{
        __raw_writel(0x1, sfrbase + REG_MMU_FLUSH);
}

static void __sysmmu_tlb_invalidate_entry(void __iomem *sfrbase,
                                sysmmu_iova_t iova, unsigned int num_inv)
{
        unsigned int i;

        for (i = 0; i < num_inv; i++) {
                __raw_writel((iova & SPAGE_MASK) | 1,
                                sfrbase + REG_MMU_FLUSH_ENTRY);
                iova += SPAGE_SIZE;
        }
}

static void __sysmmu_set_ptbase(void __iomem *sfrbase,
                                       phys_addr_t pgd)
{
        __raw_writel(pgd, sfrbase + REG_PT_BASE_ADDR);

        __sysmmu_tlb_invalidate(sfrbase);
}

static void show_fault_information(const char *name,
                enum exynos_sysmmu_inttype itype,
                phys_addr_t pgtable_base, sysmmu_iova_t fault_addr)
{
        sysmmu_pte_t *ent;

        if ((itype >= SYSMMU_FAULTS_NUM) || (itype < SYSMMU_PAGEFAULT))
                itype = SYSMMU_FAULT_UNKNOWN;

        pr_err("%s occurred at %#x by %s(Page table base: %pa)\n",
                sysmmu_fault_name[itype], fault_addr, name, &pgtable_base);

        ent = section_entry(phys_to_virt(pgtable_base), fault_addr);
        pr_err("\tLv1 entry: %#x\n", *ent);

        if (lv1ent_page(ent)) {
                ent = page_entry(ent, fault_addr);
                pr_err("\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;
        enum exynos_sysmmu_inttype itype;
        sysmmu_iova_t addr = -1;
        int ret = -ENOSYS;

        WARN_ON(!is_sysmmu_active(data));

        spin_lock(&data->lock);

        if (!IS_ERR(data->clk_master))
                clk_enable(data->clk_master);

        itype = (enum exynos_sysmmu_inttype)
                __ffs(__raw_readl(data->sfrbase + REG_INT_STATUS));
        if (WARN_ON(!((itype >= 0) && (itype < SYSMMU_FAULT_UNKNOWN))))
                itype = SYSMMU_FAULT_UNKNOWN;
        else
                addr = __raw_readl(data->sfrbase + fault_reg_offset[itype]);

        if (itype == SYSMMU_FAULT_UNKNOWN) {
                pr_err("%s: Fault is not occurred by System MMU '%s'!\n",
                        __func__, dev_name(data->sysmmu));
                pr_err("%s: Please check if IRQ is correctly configured.\n",
                        __func__);
                BUG();
        } else {
                unsigned int base =
                                __raw_readl(data->sfrbase + REG_PT_BASE_ADDR);
                show_fault_information(dev_name(data->sysmmu),
                                        itype, base, addr);
                if (data->domain)
                        ret = report_iommu_fault(data->domain,
                                        data->master, addr, itype);
        }

        /* fault is not recovered by fault handler */
        BUG_ON(ret != 0);

        __raw_writel(1 << itype, data->sfrbase + REG_INT_CLEAR);

        sysmmu_unblock(data->sfrbase);

        if (!IS_ERR(data->clk_master))
                clk_disable(data->clk_master);

        spin_unlock(&data->lock);

        return IRQ_HANDLED;
}

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

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

        clk_disable(data->clk);
        if (!IS_ERR(data->clk_master))
                clk_disable(data->clk_master);
}

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 = CFG_LRU | CFG_QOS(15);
        unsigned int ver;

        ver = __raw_sysmmu_version(data);
        if (MMU_MAJ_VER(ver) == 3) {
                if (MMU_MIN_VER(ver) >= 2) {
                        cfg |= CFG_FLPDCACHE;
                        if (MMU_MIN_VER(ver) == 3) {
                                cfg |= CFG_ACGEN;
                                cfg &= ~CFG_LRU;
                        } else {
                                cfg |= CFG_SYSSEL;
                        }
                }
        }

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

static void __sysmmu_enable_nocount(struct sysmmu_drvdata *data)
{
        if (!IS_ERR(data->clk_master))
                clk_enable(data->clk_master);
        clk_enable(data->clk);

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

        __sysmmu_init_config(data);

        __sysmmu_set_ptbase(data->sfrbase, data->pgtable);

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

        if (!IS_ERR(data->clk_master))
                clk_disable(data->clk_master);
}

static int __sysmmu_enable(struct sysmmu_drvdata *data,
                        phys_addr_t pgtable, struct 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;
}

/* __exynos_sysmmu_enable: Enables System MMU
 *
 * returns -error if an error occurred and System MMU is not enabled,
 * 0 if the System MMU has been just enabled and 1 if System MMU was already
 * enabled before.
 */
static int __exynos_sysmmu_enable(struct device *dev, phys_addr_t pgtable,
                                  struct iommu_domain *domain)
{
        int ret = 0;
        unsigned long flags;
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        struct sysmmu_drvdata *data;

        BUG_ON(!has_sysmmu(dev));

        spin_lock_irqsave(&owner->lock, flags);

        data = dev_get_drvdata(owner->sysmmu);

        ret = __sysmmu_enable(data, pgtable, domain);
        if (ret >= 0)
                data->master = dev;

        spin_unlock_irqrestore(&owner->lock, flags);

        return ret;
}

int exynos_sysmmu_enable(struct device *dev, phys_addr_t pgtable)
{
        BUG_ON(!memblock_is_memory(pgtable));

        return __exynos_sysmmu_enable(dev, pgtable, NULL);
}

static bool exynos_sysmmu_disable(struct device *dev)
{
        unsigned long flags;
        bool disabled = true;
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        struct sysmmu_drvdata *data;

        BUG_ON(!has_sysmmu(dev));

        spin_lock_irqsave(&owner->lock, flags);

        data = dev_get_drvdata(owner->sysmmu);

        disabled = __sysmmu_disable(data);
        if (disabled)
                data->master = NULL;

        spin_unlock_irqrestore(&owner->lock, flags);

        return disabled;
}

static void __sysmmu_tlb_invalidate_flpdcache(struct sysmmu_drvdata *data,
                                              sysmmu_iova_t iova)
{
        if (__raw_sysmmu_version(data) == MAKE_MMU_VER(3, 3))
                __raw_writel(iova | 0x1, data->sfrbase + REG_MMU_FLUSH_ENTRY);
}

static void sysmmu_tlb_invalidate_flpdcache(struct device *dev,
                                            sysmmu_iova_t iova)
{
        unsigned long flags;
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        struct sysmmu_drvdata *data = dev_get_drvdata(owner->sysmmu);

        if (!IS_ERR(data->clk_master))
                clk_enable(data->clk_master);

        spin_lock_irqsave(&data->lock, flags);
        if (is_sysmmu_active(data))
                __sysmmu_tlb_invalidate_flpdcache(data, iova);
        spin_unlock_irqrestore(&data->lock, flags);

        if (!IS_ERR(data->clk_master))
                clk_disable(data->clk_master);
}

static void sysmmu_tlb_invalidate_entry(struct device *dev, sysmmu_iova_t iova,
                                        size_t size)
{
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        unsigned long flags;
        struct sysmmu_drvdata *data;

        data = dev_get_drvdata(owner->sysmmu);

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

                if (!IS_ERR(data->clk_master))
                        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(__raw_sysmmu_version(data)) == 2)
                        num_inv = min_t(unsigned int, size / PAGE_SIZE, 64);

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

void exynos_sysmmu_tlb_invalidate(struct device *dev)
{
        struct exynos_iommu_owner *owner = dev->archdata.iommu;
        unsigned long flags;
        struct sysmmu_drvdata *data;

        data = dev_get_drvdata(owner->sysmmu);

        spin_lock_irqsave(&data->lock, flags);
        if (is_sysmmu_active(data)) {
                if (!IS_ERR(data->clk_master))
                        clk_enable(data->clk_master);
                if (sysmmu_block(data->sfrbase)) {
                        __sysmmu_tlb_invalidate(data->sfrbase);
                        sysmmu_unblock(data->sfrbase);
                }
                if (!IS_ERR(data->clk_master))
                        clk_disable(data->clk_master);
        } else {
                dev_dbg(dev, "disabled. Skipping TLB invalidation\n");
        }
        spin_unlock_irqrestore(&data->lock, flags);
}

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 (IS_ERR(data->clk)) {
                dev_err(dev, "Failed to get clock!\n");
                return PTR_ERR(data->clk);
        } else  {
                ret = clk_prepare(data->clk);
                if (ret) {
                        dev_err(dev, "Failed to prepare clk\n");
                        return ret;
                }
        }

        data->clk_master = devm_clk_get(dev, "master");
        if (!IS_ERR(data->clk_master)) {
                ret = clk_prepare(data->clk_master);
                if (ret) {
                        clk_unprepare(data->clk);
                        dev_err(dev, "Failed to prepare master's clk\n");
                        return ret;
                }
        }

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

        platform_set_drvdata(pdev, data);

        pm_runtime_enable(dev);

        return 0;
}

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,
        }
};

static inline void pgtable_flush(void *vastart, void *vaend)
{
        dmac_flush_range(vastart, vaend);
        outer_flush_range(virt_to_phys(vastart),
                                virt_to_phys(vaend));
}

static struct iommu_domain *exynos_iommu_domain_alloc(unsigned type)
{
        struct exynos_iommu_domain *exynos_domain;
        int i;

        if (type != IOMMU_DOMAIN_UNMANAGED)
                return NULL;

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

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

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

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

        pgtable_flush(exynos_domain->pgtable, exynos_domain->pgtable + NUM_LV1ENTRIES);

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

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

        return &exynos_domain->domain;

err_counter:
        free_pages((unsigned long)exynos_domain->pgtable, 2);
err_pgtable:
        kfree(exynos_domain);
        return NULL;
}

static void exynos_iommu_domain_free(struct iommu_domain *domain)
{
        struct exynos_iommu_domain *priv = to_exynos_domain(domain);
        struct exynos_iommu_owner *owner;
        unsigned long flags;
        int i;

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

        spin_lock_irqsave(&priv->lock, flags);

        list_for_each_entry(owner, &priv->clients, client) {
                while (!exynos_sysmmu_disable(owner->dev))
                        ; /* until System MMU is actually disabled */
        }

        while (!list_empty(&priv->clients))
                list_del_init(priv->clients.next);

        spin_unlock_irqrestore(&priv->lock, flags);

        for (i = 0; i < NUM_LV1ENTRIES; i++)
                if (lv1ent_page(priv->pgtable + i))
                        kmem_cache_free(lv2table_kmem_cache,
                                phys_to_virt(lv2table_base(priv->pgtable + i)));

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

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

        spin_lock_irqsave(&priv->lock, flags);

        ret = __exynos_sysmmu_enable(dev, pagetable, domain);
        if (ret == 0) {
                list_add_tail(&owner->client, &priv->clients);
                owner->domain = domain;
        }

        spin_unlock_irqrestore(&priv->lock, flags);

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

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

        return ret;
}

static void exynos_iommu_detach_device(struct iommu_domain *domain,
                                    struct device *dev)
{
        struct exynos_iommu_owner *owner;
        struct exynos_iommu_domain *priv = to_exynos_domain(domain);
        phys_addr_t pagetable = virt_to_phys(priv->pgtable);
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);

        list_for_each_entry(owner, &priv->clients, client) {
                if (owner == dev->archdata.iommu) {
                        if (exynos_sysmmu_disable(dev)) {
                                list_del_init(&owner->client);
                                owner->domain = NULL;
                        }
                        break;
                }
        }

        spin_unlock_irqrestore(&priv->lock, flags);

        if (owner == dev->archdata.iommu)
                dev_dbg(dev, "%s: Detached IOMMU with pgtable %pa\n",
                                        __func__, &pagetable);
        else
                dev_err(dev, "%s: No IOMMU is attached\n", __func__);
}

static sysmmu_pte_t *alloc_lv2entry(struct exynos_iommu_domain *priv,
                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((unsigned int)pent & (LV2TABLE_SIZE - 1));
                if (!pent)
                        return ERR_PTR(-ENOMEM);

                *sent = mk_lv1ent_page(virt_to_phys(pent));
                *pgcounter = NUM_LV2ENTRIES;
                pgtable_flush(pent, pent + NUM_LV2ENTRIES);
                pgtable_flush(sent, sent + 1);

                /*
                 * 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 exynos_iommu_owner *owner;

                        spin_lock(&priv->lock);
                        list_for_each_entry(owner, &priv->clients, client)
                                sysmmu_tlb_invalidate_flpdcache(
                                                        owner->dev, iova);
                        spin_unlock(&priv->lock);
                }
        }

        return page_entry(sent, iova);
}

static int lv1set_section(struct exynos_iommu_domain *priv,
                          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;
        }

        *sent = mk_lv1ent_sect(paddr);

        pgtable_flush(sent, sent + 1);

        spin_lock(&priv->lock);
        if (lv1ent_page_zero(sent)) {
                struct exynos_iommu_owner *owner;
                /*
                 * 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(owner, &priv->clients, client)
                        sysmmu_tlb_invalidate_flpdcache(owner->dev, iova);
        }
        spin_unlock(&priv->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;

                *pent = mk_lv2ent_spage(paddr);
                pgtable_flush(pent, pent + 1);
                *pgcnt -= 1;
        } else { /* size == LPAGE_SIZE */
                int i;

                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);
                }
                pgtable_flush(pent - SPAGES_PER_LPAGE, pent);
                *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 *domain, unsigned long l_iova,
                         phys_addr_t paddr, size_t size, int prot)
{
        struct exynos_iommu_domain *priv = to_exynos_domain(domain);
        sysmmu_pte_t *entry;
        sysmmu_iova_t iova = (sysmmu_iova_t)l_iova;

        unsigned long flags;
        int ret = -ENOMEM;

        BUG_ON(priv->pgtable == NULL);

        spin_lock_irqsave(&priv->pgtablelock, flags);

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

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

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

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

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

        spin_unlock_irqrestore(&priv->pgtablelock, flags);

        return ret;
}

static void exynos_iommu_tlb_invalidate_entry(struct exynos_iommu_domain *priv,
                                                sysmmu_iova_t iova, size_t size)
{
        struct exynos_iommu_owner *owner;
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);

        list_for_each_entry(owner, &priv->clients, client)
                sysmmu_tlb_invalidate_entry(owner->dev, iova, size);

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

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

        BUG_ON(priv->pgtable == NULL);

        spin_lock_irqsave(&priv->pgtablelock, flags);

        ent = section_entry(priv->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 */
                *ent = ZERO_LV2LINK;
                pgtable_flush(ent, ent + 1);
                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)) {
                *ent = 0;
                size = SPAGE_SIZE;
                pgtable_flush(ent, ent + 1);
                priv->lv2entcnt[lv1ent_offset(iova)] += 1;
                goto done;
        }

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

        memset(ent, 0, sizeof(*ent) * SPAGES_PER_LPAGE);
        pgtable_flush(ent, ent + SPAGES_PER_LPAGE);

        size = LPAGE_SIZE;
        priv->lv2entcnt[lv1ent_offset(iova)] += SPAGES_PER_LPAGE;
done:
        spin_unlock_irqrestore(&priv->pgtablelock, flags);

        exynos_iommu_tlb_invalidate_entry(priv, iova, size);

        return size;
err:
        spin_unlock_irqrestore(&priv->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 *domain,
                                          dma_addr_t iova)
{
        struct exynos_iommu_domain *priv = to_exynos_domain(domain);
        sysmmu_pte_t *entry;
        unsigned long flags;
        phys_addr_t phys = 0;

        spin_lock_irqsave(&priv->pgtablelock, flags);

        entry = section_entry(priv->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(&priv->pgtablelock, flags);

        return phys;
}

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

        group = iommu_group_get(dev);

        if (!group) {
                group = iommu_group_alloc();
                if (IS_ERR(group)) {
                        dev_err(dev, "Failed to allocate IOMMU group\n");
                        return PTR_ERR(group);
                }
        }

        ret = iommu_group_add_device(group, dev);
        iommu_group_put(group);

        return ret;
}

static void exynos_iommu_remove_device(struct device *dev)
{
        iommu_group_remove_device(dev);
}

static const 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,
        .add_device = exynos_iommu_add_device,
        .remove_device = exynos_iommu_remove_device,
        .pgsize_bitmap = SECT_SIZE | LPAGE_SIZE | SPAGE_SIZE,
};

static int __init exynos_iommu_init(void)
{
        struct device_node *np;
        int ret;

        np = of_find_matching_node(NULL, sysmmu_of_match);
        if (!np)
                return 0;

        of_node_put(np);

        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;
        }

        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;
}
subsys_initcall(exynos_iommu_init);