/*
 * CPU-agnostic ARM page table allocator.
 *
 * ARMv7 Short-descriptor format, supporting
 * - Basic memory attributes
 * - Simplified access permissions (AP[2:1] model)
 * - Backwards-compatible TEX remap
 * - Large pages/supersections (if indicated by the caller)
 *
 * Not supporting:
 * - Legacy access permissions (AP[2:0] model)
 *
 * Almost certainly never supporting:
 * - PXN
 * - Domains
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright (C) 2014-2015 ARM Limited
 * Copyright (c) 2014-2015 MediaTek Inc.
 */

#define pr_fmt(fmt)     "arm-v7s io-pgtable: " fmt

#include <linux/atomic.h>
#include <linux/dma-mapping.h>
#include <linux/gfp.h>
#include <linux/iommu.h>
#include <linux/kernel.h>
#include <linux/kmemleak.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>

#include <asm/barrier.h>

#include "io-pgtable.h"

/* Struct accessors */
#define io_pgtable_to_data(x)                                           \
        container_of((x), struct arm_v7s_io_pgtable, iop)

#define io_pgtable_ops_to_data(x)                                       \
        io_pgtable_to_data(io_pgtable_ops_to_pgtable(x))

/*
 * We have 32 bits total; 12 bits resolved at level 1, 8 bits at level 2,
 * and 12 bits in a page. With some carefully-chosen coefficients we can
 * hide the ugly inconsistencies behind these macros and at least let the
 * rest of the code pretend to be somewhat sane.
 */
#define ARM_V7S_ADDR_BITS               32
#define _ARM_V7S_LVL_BITS(lvl)          (16 - (lvl) * 4)
#define ARM_V7S_LVL_SHIFT(lvl)          (ARM_V7S_ADDR_BITS - (4 + 8 * (lvl)))
#define ARM_V7S_TABLE_SHIFT             10

#define ARM_V7S_PTES_PER_LVL(lvl)       (1 << _ARM_V7S_LVL_BITS(lvl))
#define ARM_V7S_TABLE_SIZE(lvl)                                         \
        (ARM_V7S_PTES_PER_LVL(lvl) * sizeof(arm_v7s_iopte))

#define ARM_V7S_BLOCK_SIZE(lvl)         (1UL << ARM_V7S_LVL_SHIFT(lvl))
#define ARM_V7S_LVL_MASK(lvl)           ((u32)(~0U << ARM_V7S_LVL_SHIFT(lvl)))
#define ARM_V7S_TABLE_MASK              ((u32)(~0U << ARM_V7S_TABLE_SHIFT))
#define _ARM_V7S_IDX_MASK(lvl)          (ARM_V7S_PTES_PER_LVL(lvl) - 1)
#define ARM_V7S_LVL_IDX(addr, lvl)      ({                              \
        int _l = lvl;                                                   \
        ((u32)(addr) >> ARM_V7S_LVL_SHIFT(_l)) & _ARM_V7S_IDX_MASK(_l); \
})

/*
 * Large page/supersection entries are effectively a block of 16 page/section
 * entries, along the lines of the LPAE contiguous hint, but all with the
 * same output address. For want of a better common name we'll call them
 * "contiguous" versions of their respective page/section entries here, but
 * noting the distinction (WRT to TLB maintenance) that they represent *one*
 * entry repeated 16 times, not 16 separate entries (as in the LPAE case).
 */
#define ARM_V7S_CONT_PAGES              16

/* PTE type bits: these are all mixed up with XN/PXN bits in most cases */
#define ARM_V7S_PTE_TYPE_TABLE          0x1
#define ARM_V7S_PTE_TYPE_PAGE           0x2
#define ARM_V7S_PTE_TYPE_CONT_PAGE      0x1

#define ARM_V7S_PTE_IS_VALID(pte)       (((pte) & 0x3) != 0)
#define ARM_V7S_PTE_IS_TABLE(pte, lvl) \
        ((lvl) == 1 && (((pte) & 0x3) == ARM_V7S_PTE_TYPE_TABLE))

/* Page table bits */
#define ARM_V7S_ATTR_XN(lvl)            BIT(4 * (2 - (lvl)))
#define ARM_V7S_ATTR_B                  BIT(2)
#define ARM_V7S_ATTR_C                  BIT(3)
#define ARM_V7S_ATTR_NS_TABLE           BIT(3)
#define ARM_V7S_ATTR_NS_SECTION         BIT(19)

#define ARM_V7S_CONT_SECTION            BIT(18)
#define ARM_V7S_CONT_PAGE_XN_SHIFT      15

/*
 * The attribute bits are consistently ordered*, but occupy bits [17:10] of
 * a level 1 PTE vs. bits [11:4] at level 2. Thus we define the individual
 * fields relative to that 8-bit block, plus a total shift relative to the PTE.
 */
#define ARM_V7S_ATTR_SHIFT(lvl)         (16 - (lvl) * 6)

#define ARM_V7S_ATTR_MASK               0xff
#define ARM_V7S_ATTR_AP0                BIT(0)
#define ARM_V7S_ATTR_AP1                BIT(1)
#define ARM_V7S_ATTR_AP2                BIT(5)
#define ARM_V7S_ATTR_S                  BIT(6)
#define ARM_V7S_ATTR_NG                 BIT(7)
#define ARM_V7S_TEX_SHIFT               2
#define ARM_V7S_TEX_MASK                0x7
#define ARM_V7S_ATTR_TEX(val)           (((val) & ARM_V7S_TEX_MASK) << ARM_V7S_TEX_SHIFT)

#define ARM_V7S_ATTR_MTK_4GB            BIT(9) /* MTK extend it for 4GB mode */

/* *well, except for TEX on level 2 large pages, of course :( */
#define ARM_V7S_CONT_PAGE_TEX_SHIFT     6
#define ARM_V7S_CONT_PAGE_TEX_MASK      (ARM_V7S_TEX_MASK << ARM_V7S_CONT_PAGE_TEX_SHIFT)

/* Simplified access permissions */
#define ARM_V7S_PTE_AF                  ARM_V7S_ATTR_AP0
#define ARM_V7S_PTE_AP_UNPRIV           ARM_V7S_ATTR_AP1
#define ARM_V7S_PTE_AP_RDONLY           ARM_V7S_ATTR_AP2

/* Register bits */
#define ARM_V7S_RGN_NC                  0
#define ARM_V7S_RGN_WBWA                1
#define ARM_V7S_RGN_WT                  2
#define ARM_V7S_RGN_WB                  3

#define ARM_V7S_PRRR_TYPE_DEVICE        1
#define ARM_V7S_PRRR_TYPE_NORMAL        2
#define ARM_V7S_PRRR_TR(n, type)        (((type) & 0x3) << ((n) * 2))
#define ARM_V7S_PRRR_DS0                BIT(16)
#define ARM_V7S_PRRR_DS1                BIT(17)
#define ARM_V7S_PRRR_NS0                BIT(18)
#define ARM_V7S_PRRR_NS1                BIT(19)
#define ARM_V7S_PRRR_NOS(n)             BIT((n) + 24)

#define ARM_V7S_NMRR_IR(n, attr)        (((attr) & 0x3) << ((n) * 2))
#define ARM_V7S_NMRR_OR(n, attr)        (((attr) & 0x3) << ((n) * 2 + 16))

#define ARM_V7S_TTBR_S                  BIT(1)
#define ARM_V7S_TTBR_NOS                BIT(5)
#define ARM_V7S_TTBR_ORGN_ATTR(attr)    (((attr) & 0x3) << 3)
#define ARM_V7S_TTBR_IRGN_ATTR(attr)                                    \
        ((((attr) & 0x1) << 6) | (((attr) & 0x2) >> 1))

#define ARM_V7S_TCR_PD1                 BIT(5)

typedef u32 arm_v7s_iopte;

static bool selftest_running;

struct arm_v7s_io_pgtable {
        struct io_pgtable       iop;

        arm_v7s_iopte           *pgd;
        struct kmem_cache       *l2_tables;
        spinlock_t              split_lock;
};

static dma_addr_t __arm_v7s_dma_addr(void *pages)
{
        return (dma_addr_t)virt_to_phys(pages);
}

static arm_v7s_iopte *iopte_deref(arm_v7s_iopte pte, int lvl)
{
        if (ARM_V7S_PTE_IS_TABLE(pte, lvl))
                pte &= ARM_V7S_TABLE_MASK;
        else
                pte &= ARM_V7S_LVL_MASK(lvl);
        return phys_to_virt(pte);
}

static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
                                   struct arm_v7s_io_pgtable *data)
{
        struct io_pgtable_cfg *cfg = &data->iop.cfg;
        struct device *dev = cfg->iommu_dev;
        dma_addr_t dma;
        size_t size = ARM_V7S_TABLE_SIZE(lvl);
        void *table = NULL;

        if (lvl == 1)
                table = (void *)__get_dma_pages(__GFP_ZERO, get_order(size));
        else if (lvl == 2)
                table = kmem_cache_zalloc(data->l2_tables, gfp | GFP_DMA);
        if (table && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
                dma = dma_map_single(dev, table, size, DMA_TO_DEVICE);
                if (dma_mapping_error(dev, dma))
                        goto out_free;
                /*
                 * We depend on the IOMMU being able to work with any physical
                 * address directly, so if the DMA layer suggests otherwise by
                 * translating or truncating them, that bodes very badly...
                 */
                if (dma != virt_to_phys(table))
                        goto out_unmap;
        }
        kmemleak_ignore(table);
        return table;

out_unmap:
        dev_err(dev, "Cannot accommodate DMA translation for IOMMU page tables\n");
        dma_unmap_single(dev, dma, size, DMA_TO_DEVICE);
out_free:
        if (lvl == 1)
                free_pages((unsigned long)table, get_order(size));
        else
                kmem_cache_free(data->l2_tables, table);
        return NULL;
}

static void __arm_v7s_free_table(void *table, int lvl,
                                 struct arm_v7s_io_pgtable *data)
{
        struct io_pgtable_cfg *cfg = &data->iop.cfg;
        struct device *dev = cfg->iommu_dev;
        size_t size = ARM_V7S_TABLE_SIZE(lvl);

        if (!(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA))
                dma_unmap_single(dev, __arm_v7s_dma_addr(table), size,
                                 DMA_TO_DEVICE);
        if (lvl == 1)
                free_pages((unsigned long)table, get_order(size));
        else
                kmem_cache_free(data->l2_tables, table);
}

static void __arm_v7s_pte_sync(arm_v7s_iopte *ptep, int num_entries,
                               struct io_pgtable_cfg *cfg)
{
        if (cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)
                return;

        dma_sync_single_for_device(cfg->iommu_dev, __arm_v7s_dma_addr(ptep),
                                   num_entries * sizeof(*ptep), DMA_TO_DEVICE);
}
static void __arm_v7s_set_pte(arm_v7s_iopte *ptep, arm_v7s_iopte pte,
                              int num_entries, struct io_pgtable_cfg *cfg)
{
        int i;

        for (i = 0; i < num_entries; i++)
                ptep[i] = pte;

        __arm_v7s_pte_sync(ptep, num_entries, cfg);
}

static arm_v7s_iopte arm_v7s_prot_to_pte(int prot, int lvl,
                                         struct io_pgtable_cfg *cfg)
{
        bool ap = !(cfg->quirks & IO_PGTABLE_QUIRK_NO_PERMS);
        arm_v7s_iopte pte = ARM_V7S_ATTR_NG | ARM_V7S_ATTR_S;

        if (!(prot & IOMMU_MMIO))
                pte |= ARM_V7S_ATTR_TEX(1);
        if (ap) {
                pte |= ARM_V7S_PTE_AF;
                if (!(prot & IOMMU_PRIV))
                        pte |= ARM_V7S_PTE_AP_UNPRIV;
                if (!(prot & IOMMU_WRITE))
                        pte |= ARM_V7S_PTE_AP_RDONLY;
        }
        pte <<= ARM_V7S_ATTR_SHIFT(lvl);

        if ((prot & IOMMU_NOEXEC) && ap)
                pte |= ARM_V7S_ATTR_XN(lvl);
        if (prot & IOMMU_MMIO)
                pte |= ARM_V7S_ATTR_B;
        else if (prot & IOMMU_CACHE)
                pte |= ARM_V7S_ATTR_B | ARM_V7S_ATTR_C;

        pte |= ARM_V7S_PTE_TYPE_PAGE;
        if (lvl == 1 && (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS))
                pte |= ARM_V7S_ATTR_NS_SECTION;

        if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_4GB)
                pte |= ARM_V7S_ATTR_MTK_4GB;

        return pte;
}

static int arm_v7s_pte_to_prot(arm_v7s_iopte pte, int lvl)
{
        int prot = IOMMU_READ;
        arm_v7s_iopte attr = pte >> ARM_V7S_ATTR_SHIFT(lvl);

        if (!(attr & ARM_V7S_PTE_AP_RDONLY))
                prot |= IOMMU_WRITE;
        if (!(attr & ARM_V7S_PTE_AP_UNPRIV))
                prot |= IOMMU_PRIV;
        if ((attr & (ARM_V7S_TEX_MASK << ARM_V7S_TEX_SHIFT)) == 0)
                prot |= IOMMU_MMIO;
        else if (pte & ARM_V7S_ATTR_C)
                prot |= IOMMU_CACHE;
        if (pte & ARM_V7S_ATTR_XN(lvl))
                prot |= IOMMU_NOEXEC;

        return prot;
}

static arm_v7s_iopte arm_v7s_pte_to_cont(arm_v7s_iopte pte, int lvl)
{
        if (lvl == 1) {
                pte |= ARM_V7S_CONT_SECTION;
        } else if (lvl == 2) {
                arm_v7s_iopte xn = pte & ARM_V7S_ATTR_XN(lvl);
                arm_v7s_iopte tex = pte & ARM_V7S_CONT_PAGE_TEX_MASK;

                pte ^= xn | tex | ARM_V7S_PTE_TYPE_PAGE;
                pte |= (xn << ARM_V7S_CONT_PAGE_XN_SHIFT) |
                       (tex << ARM_V7S_CONT_PAGE_TEX_SHIFT) |
                       ARM_V7S_PTE_TYPE_CONT_PAGE;
        }
        return pte;
}

static arm_v7s_iopte arm_v7s_cont_to_pte(arm_v7s_iopte pte, int lvl)
{
        if (lvl == 1) {
                pte &= ~ARM_V7S_CONT_SECTION;
        } else if (lvl == 2) {
                arm_v7s_iopte xn = pte & BIT(ARM_V7S_CONT_PAGE_XN_SHIFT);
                arm_v7s_iopte tex = pte & (ARM_V7S_CONT_PAGE_TEX_MASK <<
                                           ARM_V7S_CONT_PAGE_TEX_SHIFT);

                pte ^= xn | tex | ARM_V7S_PTE_TYPE_CONT_PAGE;
                pte |= (xn >> ARM_V7S_CONT_PAGE_XN_SHIFT) |
                       (tex >> ARM_V7S_CONT_PAGE_TEX_SHIFT) |
                       ARM_V7S_PTE_TYPE_PAGE;
        }
        return pte;
}

static bool arm_v7s_pte_is_cont(arm_v7s_iopte pte, int lvl)
{
        if (lvl == 1 && !ARM_V7S_PTE_IS_TABLE(pte, lvl))
                return pte & ARM_V7S_CONT_SECTION;
        else if (lvl == 2)
                return !(pte & ARM_V7S_PTE_TYPE_PAGE);
        return false;
}

static int __arm_v7s_unmap(struct arm_v7s_io_pgtable *, unsigned long,
                           size_t, int, arm_v7s_iopte *);

static int arm_v7s_init_pte(struct arm_v7s_io_pgtable *data,
                            unsigned long iova, phys_addr_t paddr, int prot,
                            int lvl, int num_entries, arm_v7s_iopte *ptep)
{
        struct io_pgtable_cfg *cfg = &data->iop.cfg;
        arm_v7s_iopte pte;
        int i;

        for (i = 0; i < num_entries; i++)
                if (ARM_V7S_PTE_IS_TABLE(ptep[i], lvl)) {
                        /*
                         * We need to unmap and free the old table before
                         * overwriting it with a block entry.
                         */
                        arm_v7s_iopte *tblp;
                        size_t sz = ARM_V7S_BLOCK_SIZE(lvl);

                        tblp = ptep - ARM_V7S_LVL_IDX(iova, lvl);
                        if (WARN_ON(__arm_v7s_unmap(data, iova + i * sz,
                                                    sz, lvl, tblp) != sz))
                                return -EINVAL;
                } else if (ptep[i]) {
                        /* We require an unmap first */
                        WARN_ON(!selftest_running);
                        return -EEXIST;
                }

        pte = arm_v7s_prot_to_pte(prot, lvl, cfg);
        if (num_entries > 1)
                pte = arm_v7s_pte_to_cont(pte, lvl);

        pte |= paddr & ARM_V7S_LVL_MASK(lvl);

        __arm_v7s_set_pte(ptep, pte, num_entries, cfg);
        return 0;
}

static arm_v7s_iopte arm_v7s_install_table(arm_v7s_iopte *table,
                                           arm_v7s_iopte *ptep,
                                           arm_v7s_iopte curr,
                                           struct io_pgtable_cfg *cfg)
{
        arm_v7s_iopte old, new;

        new = virt_to_phys(table) | ARM_V7S_PTE_TYPE_TABLE;
        if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS)
                new |= ARM_V7S_ATTR_NS_TABLE;

        /*
         * Ensure the table itself is visible before its PTE can be.
         * Whilst we could get away with cmpxchg64_release below, this
         * doesn't have any ordering semantics when !CONFIG_SMP.
         */
        dma_wmb();

        old = cmpxchg_relaxed(ptep, curr, new);
        __arm_v7s_pte_sync(ptep, 1, cfg);

        return old;
}

static int __arm_v7s_map(struct arm_v7s_io_pgtable *data, unsigned long iova,
                         phys_addr_t paddr, size_t size, int prot,
                         int lvl, arm_v7s_iopte *ptep)
{
        struct io_pgtable_cfg *cfg = &data->iop.cfg;
        arm_v7s_iopte pte, *cptep;
        int num_entries = size >> ARM_V7S_LVL_SHIFT(lvl);

        /* Find our entry at the current level */
        ptep += ARM_V7S_LVL_IDX(iova, lvl);

        /* If we can install a leaf entry at this level, then do so */
        if (num_entries)
                return arm_v7s_init_pte(data, iova, paddr, prot,
                                        lvl, num_entries, ptep);

        /* We can't allocate tables at the final level */
        if (WARN_ON(lvl == 2))
                return -EINVAL;

        /* Grab a pointer to the next level */
        pte = READ_ONCE(*ptep);
        if (!pte) {
                cptep = __arm_v7s_alloc_table(lvl + 1, GFP_ATOMIC, data);
                if (!cptep)
                        return -ENOMEM;

                pte = arm_v7s_install_table(cptep, ptep, 0, cfg);
                if (pte)
                        __arm_v7s_free_table(cptep, lvl + 1, data);
        } else {
                /* We've no easy way of knowing if it's synced yet, so... */
                __arm_v7s_pte_sync(ptep, 1, cfg);
        }

        if (ARM_V7S_PTE_IS_TABLE(pte, lvl)) {
                cptep = iopte_deref(pte, lvl);
        } else if (pte) {
                /* We require an unmap first */
                WARN_ON(!selftest_running);
                return -EEXIST;
        }

        /* Rinse, repeat */
        return __arm_v7s_map(data, iova, paddr, size, prot, lvl + 1, cptep);
}

static int arm_v7s_map(struct io_pgtable_ops *ops, unsigned long iova,
                        phys_addr_t paddr, size_t size, int prot)
{
        struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
        struct io_pgtable *iop = &data->iop;
        int ret;

        /* If no access, then nothing to do */
        if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
                return 0;

        if (WARN_ON(upper_32_bits(iova) || upper_32_bits(paddr)))
                return -ERANGE;

        ret = __arm_v7s_map(data, iova, paddr, size, prot, 1, data->pgd);
        /*
         * Synchronise all PTE updates for the new mapping before there's
         * a chance for anything to kick off a table walk for the new iova.
         */
        if (iop->cfg.quirks & IO_PGTABLE_QUIRK_TLBI_ON_MAP) {
                io_pgtable_tlb_add_flush(iop, iova, size,
                                         ARM_V7S_BLOCK_SIZE(2), false);
                io_pgtable_tlb_sync(iop);
        } else {
                wmb();
        }

        return ret;
}

static void arm_v7s_free_pgtable(struct io_pgtable *iop)
{
        struct arm_v7s_io_pgtable *data = io_pgtable_to_data(iop);
        int i;

        for (i = 0; i < ARM_V7S_PTES_PER_LVL(1); i++) {
                arm_v7s_iopte pte = data->pgd[i];

                if (ARM_V7S_PTE_IS_TABLE(pte, 1))
                        __arm_v7s_free_table(iopte_deref(pte, 1), 2, data);
        }
        __arm_v7s_free_table(data->pgd, 1, data);
        kmem_cache_destroy(data->l2_tables);
        kfree(data);
}

static arm_v7s_iopte arm_v7s_split_cont(struct arm_v7s_io_pgtable *data,
                                        unsigned long iova, int idx, int lvl,
                                        arm_v7s_iopte *ptep)
{
        struct io_pgtable *iop = &data->iop;
        arm_v7s_iopte pte;
        size_t size = ARM_V7S_BLOCK_SIZE(lvl);
        int i;

        /* Check that we didn't lose a race to get the lock */
        pte = *ptep;
        if (!arm_v7s_pte_is_cont(pte, lvl))
                return pte;

        ptep -= idx & (ARM_V7S_CONT_PAGES - 1);
        pte = arm_v7s_cont_to_pte(pte, lvl);
        for (i = 0; i < ARM_V7S_CONT_PAGES; i++)
                ptep[i] = pte + i * size;

        __arm_v7s_pte_sync(ptep, ARM_V7S_CONT_PAGES, &iop->cfg);

        size *= ARM_V7S_CONT_PAGES;
        io_pgtable_tlb_add_flush(iop, iova, size, size, true);
        io_pgtable_tlb_sync(iop);
        return pte;
}

static int arm_v7s_split_blk_unmap(struct arm_v7s_io_pgtable *data,
                                   unsigned long iova, size_t size,
                                   arm_v7s_iopte blk_pte, arm_v7s_iopte *ptep)
{
        struct io_pgtable_cfg *cfg = &data->iop.cfg;
        arm_v7s_iopte pte, *tablep;
        int i, unmap_idx, num_entries, num_ptes;

        tablep = __arm_v7s_alloc_table(2, GFP_ATOMIC, data);
        if (!tablep)
                return 0; /* Bytes unmapped */

        num_ptes = ARM_V7S_PTES_PER_LVL(2);
        num_entries = size >> ARM_V7S_LVL_SHIFT(2);
        unmap_idx = ARM_V7S_LVL_IDX(iova, 2);

        pte = arm_v7s_prot_to_pte(arm_v7s_pte_to_prot(blk_pte, 1), 2, cfg);
        if (num_entries > 1)
                pte = arm_v7s_pte_to_cont(pte, 2);

        for (i = 0; i < num_ptes; i += num_entries, pte += size) {
                /* Unmap! */
                if (i == unmap_idx)
                        continue;

                __arm_v7s_set_pte(&tablep[i], pte, num_entries, cfg);
        }

        pte = arm_v7s_install_table(tablep, ptep, blk_pte, cfg);
        if (pte != blk_pte) {
                __arm_v7s_free_table(tablep, 2, data);

                if (!ARM_V7S_PTE_IS_TABLE(pte, 1))
                        return 0;

                tablep = iopte_deref(pte, 1);
                return __arm_v7s_unmap(data, iova, size, 2, tablep);
        }

        io_pgtable_tlb_add_flush(&data->iop, iova, size, size, true);
        return size;
}

static int __arm_v7s_unmap(struct arm_v7s_io_pgtable *data,
                            unsigned long iova, size_t size, int lvl,
                            arm_v7s_iopte *ptep)
{
        arm_v7s_iopte pte[ARM_V7S_CONT_PAGES];
        struct io_pgtable *iop = &data->iop;
        int idx, i = 0, num_entries = size >> ARM_V7S_LVL_SHIFT(lvl);

        /* Something went horribly wrong and we ran out of page table */
        if (WARN_ON(lvl > 2))
                return 0;

        idx = ARM_V7S_LVL_IDX(iova, lvl);
        ptep += idx;
        do {
                pte[i] = READ_ONCE(ptep[i]);
                if (WARN_ON(!ARM_V7S_PTE_IS_VALID(pte[i])))
                        return 0;
        } while (++i < num_entries);

        /*
         * If we've hit a contiguous 'large page' entry at this level, it
         * needs splitting first, unless we're unmapping the whole lot.
         *
         * For splitting, we can't rewrite 16 PTEs atomically, and since we
         * can't necessarily assume TEX remap we don't have a software bit to
         * mark live entries being split. In practice (i.e. DMA API code), we
         * will never be splitting large pages anyway, so just wrap this edge
         * case in a lock for the sake of correctness and be done with it.
         */
        if (num_entries <= 1 && arm_v7s_pte_is_cont(pte[0], lvl)) {
                unsigned long flags;

                spin_lock_irqsave(&data->split_lock, flags);
                pte[0] = arm_v7s_split_cont(data, iova, idx, lvl, ptep);
                spin_unlock_irqrestore(&data->split_lock, flags);
        }

        /* If the size matches this level, we're in the right place */
        if (num_entries) {
                size_t blk_size = ARM_V7S_BLOCK_SIZE(lvl);

                __arm_v7s_set_pte(ptep, 0, num_entries, &iop->cfg);

                for (i = 0; i < num_entries; i++) {
                        if (ARM_V7S_PTE_IS_TABLE(pte[i], lvl)) {
                                /* Also flush any partial walks */
                                io_pgtable_tlb_add_flush(iop, iova, blk_size,
                                        ARM_V7S_BLOCK_SIZE(lvl + 1), false);
                                io_pgtable_tlb_sync(iop);
                                ptep = iopte_deref(pte[i], lvl);
                                __arm_v7s_free_table(ptep, lvl + 1, data);
                        } else {
                                io_pgtable_tlb_add_flush(iop, iova, blk_size,
                                                         blk_size, true);
                        }
                        iova += blk_size;
                }
                return size;
        } else if (lvl == 1 && !ARM_V7S_PTE_IS_TABLE(pte[0], lvl)) {
                /*
                 * Insert a table at the next level to map the old region,
                 * minus the part we want to unmap
                 */
                return arm_v7s_split_blk_unmap(data, iova, size, pte[0], ptep);
        }

        /* Keep on walkin' */
        ptep = iopte_deref(pte[0], lvl);
        return __arm_v7s_unmap(data, iova, size, lvl + 1, ptep);
}

static int arm_v7s_unmap(struct io_pgtable_ops *ops, unsigned long iova,
                         size_t size)
{
        struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
        size_t unmapped;

        if (WARN_ON(upper_32_bits(iova)))
                return 0;

        unmapped = __arm_v7s_unmap(data, iova, size, 1, data->pgd);
        if (unmapped)
                io_pgtable_tlb_sync(&data->iop);

        return unmapped;
}

static phys_addr_t arm_v7s_iova_to_phys(struct io_pgtable_ops *ops,
                                        unsigned long iova)
{
        struct arm_v7s_io_pgtable *data = io_pgtable_ops_to_data(ops);
        arm_v7s_iopte *ptep = data->pgd, pte;
        int lvl = 0;
        u32 mask;

        do {
                ptep += ARM_V7S_LVL_IDX(iova, ++lvl);
                pte = READ_ONCE(*ptep);
                ptep = iopte_deref(pte, lvl);
        } while (ARM_V7S_PTE_IS_TABLE(pte, lvl));

        if (!ARM_V7S_PTE_IS_VALID(pte))
                return 0;

        mask = ARM_V7S_LVL_MASK(lvl);
        if (arm_v7s_pte_is_cont(pte, lvl))
                mask *= ARM_V7S_CONT_PAGES;
        return (pte & mask) | (iova & ~mask);
}

static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
                                                void *cookie)
{
        struct arm_v7s_io_pgtable *data;

#ifdef PHYS_OFFSET
        if (upper_32_bits(PHYS_OFFSET))
                return NULL;
#endif
        if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas > ARM_V7S_ADDR_BITS)
                return NULL;

        if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
                            IO_PGTABLE_QUIRK_NO_PERMS |
                            IO_PGTABLE_QUIRK_TLBI_ON_MAP |
                            IO_PGTABLE_QUIRK_ARM_MTK_4GB |
                            IO_PGTABLE_QUIRK_NO_DMA))
                return NULL;

        /* If ARM_MTK_4GB is enabled, the NO_PERMS is also expected. */
        if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_4GB &&
            !(cfg->quirks & IO_PGTABLE_QUIRK_NO_PERMS))
                        return NULL;

        data = kmalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                return NULL;

        spin_lock_init(&data->split_lock);
        data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
                                            ARM_V7S_TABLE_SIZE(2),
                                            ARM_V7S_TABLE_SIZE(2),
                                            SLAB_CACHE_DMA, NULL);
        if (!data->l2_tables)
                goto out_free_data;

        data->iop.ops = (struct io_pgtable_ops) {
                .map            = arm_v7s_map,
                .unmap          = arm_v7s_unmap,
                .iova_to_phys   = arm_v7s_iova_to_phys,
        };

        /* We have to do this early for __arm_v7s_alloc_table to work... */
        data->iop.cfg = *cfg;

        /*
         * Unless the IOMMU driver indicates supersection support by
         * having SZ_16M set in the initial bitmap, they won't be used.
         */
        cfg->pgsize_bitmap &= SZ_4K | SZ_64K | SZ_1M | SZ_16M;

        /* TCR: T0SZ=0, disable TTBR1 */
        cfg->arm_v7s_cfg.tcr = ARM_V7S_TCR_PD1;

        /*
         * TEX remap: the indices used map to the closest equivalent types
         * under the non-TEX-remap interpretation of those attribute bits,
         * excepting various implementation-defined aspects of shareability.
         */
        cfg->arm_v7s_cfg.prrr = ARM_V7S_PRRR_TR(1, ARM_V7S_PRRR_TYPE_DEVICE) |
                                ARM_V7S_PRRR_TR(4, ARM_V7S_PRRR_TYPE_NORMAL) |
                                ARM_V7S_PRRR_TR(7, ARM_V7S_PRRR_TYPE_NORMAL) |
                                ARM_V7S_PRRR_DS0 | ARM_V7S_PRRR_DS1 |
                                ARM_V7S_PRRR_NS1 | ARM_V7S_PRRR_NOS(7);
        cfg->arm_v7s_cfg.nmrr = ARM_V7S_NMRR_IR(7, ARM_V7S_RGN_WBWA) |
                                ARM_V7S_NMRR_OR(7, ARM_V7S_RGN_WBWA);

        /* Looking good; allocate a pgd */
        data->pgd = __arm_v7s_alloc_table(1, GFP_KERNEL, data);
        if (!data->pgd)
                goto out_free_data;

        /* Ensure the empty pgd is visible before any actual TTBR write */
        wmb();

        /* TTBRs */
        cfg->arm_v7s_cfg.ttbr[0] = virt_to_phys(data->pgd) |
                                   ARM_V7S_TTBR_S | ARM_V7S_TTBR_NOS |
                                   ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_WBWA) |
                                   ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_WBWA);
        cfg->arm_v7s_cfg.ttbr[1] = 0;
        return &data->iop;

out_free_data:
        kmem_cache_destroy(data->l2_tables);
        kfree(data);
        return NULL;
}

struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns = {
        .alloc  = arm_v7s_alloc_pgtable,
        .free   = arm_v7s_free_pgtable,
};

#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S_SELFTEST

static struct io_pgtable_cfg *cfg_cookie;

static void dummy_tlb_flush_all(void *cookie)
{
        WARN_ON(cookie != cfg_cookie);
}

static void dummy_tlb_add_flush(unsigned long iova, size_t size,
                                size_t granule, bool leaf, void *cookie)
{
        WARN_ON(cookie != cfg_cookie);
        WARN_ON(!(size & cfg_cookie->pgsize_bitmap));
}

static void dummy_tlb_sync(void *cookie)
{
        WARN_ON(cookie != cfg_cookie);
}

static const struct iommu_gather_ops dummy_tlb_ops = {
        .tlb_flush_all  = dummy_tlb_flush_all,
        .tlb_add_flush  = dummy_tlb_add_flush,
        .tlb_sync       = dummy_tlb_sync,
};

#define __FAIL(ops)     ({                              \
                WARN(1, "selftest: test failed\n");     \
                selftest_running = false;               \
                -EFAULT;                                \
})

static int __init arm_v7s_do_selftests(void)
{
        struct io_pgtable_ops *ops;
        struct io_pgtable_cfg cfg = {
                .tlb = &dummy_tlb_ops,
                .oas = 32,
                .ias = 32,
                .quirks = IO_PGTABLE_QUIRK_ARM_NS | IO_PGTABLE_QUIRK_NO_DMA,
                .pgsize_bitmap = SZ_4K | SZ_64K | SZ_1M | SZ_16M,
        };
        unsigned int iova, size, iova_start;
        unsigned int i, loopnr = 0;

        selftest_running = true;

        cfg_cookie = &cfg;

        ops = alloc_io_pgtable_ops(ARM_V7S, &cfg, &cfg);
        if (!ops) {
                pr_err("selftest: failed to allocate io pgtable ops\n");
                return -EINVAL;
        }

        /*
         * Initial sanity checks.
         * Empty page tables shouldn't provide any translations.
         */
        if (ops->iova_to_phys(ops, 42))
                return __FAIL(ops);

        if (ops->iova_to_phys(ops, SZ_1G + 42))
                return __FAIL(ops);

        if (ops->iova_to_phys(ops, SZ_2G + 42))
                return __FAIL(ops);

        /*
         * Distinct mappings of different granule sizes.
         */
        iova = 0;
        for_each_set_bit(i, &cfg.pgsize_bitmap, BITS_PER_LONG) {
                size = 1UL << i;
                if (ops->map(ops, iova, iova, size, IOMMU_READ |
                                                    IOMMU_WRITE |
                                                    IOMMU_NOEXEC |
                                                    IOMMU_CACHE))
                        return __FAIL(ops);

                /* Overlapping mappings */
                if (!ops->map(ops, iova, iova + size, size,
                              IOMMU_READ | IOMMU_NOEXEC))
                        return __FAIL(ops);

                if (ops->iova_to_phys(ops, iova + 42) != (iova + 42))
                        return __FAIL(ops);

                iova += SZ_16M;
                loopnr++;
        }

        /* Partial unmap */
        i = 1;
        size = 1UL << __ffs(cfg.pgsize_bitmap);
        while (i < loopnr) {
                iova_start = i * SZ_16M;
                if (ops->unmap(ops, iova_start + size, size) != size)
                        return __FAIL(ops);

                /* Remap of partial unmap */
                if (ops->map(ops, iova_start + size, size, size, IOMMU_READ))
                        return __FAIL(ops);

                if (ops->iova_to_phys(ops, iova_start + size + 42)
                    != (size + 42))
                        return __FAIL(ops);
                i++;
        }

        /* Full unmap */
        iova = 0;
        i = find_first_bit(&cfg.pgsize_bitmap, BITS_PER_LONG);
        while (i != BITS_PER_LONG) {
                size = 1UL << i;

                if (ops->unmap(ops, iova, size) != size)
                        return __FAIL(ops);

                if (ops->iova_to_phys(ops, iova + 42))
                        return __FAIL(ops);

                /* Remap full block */
                if (ops->map(ops, iova, iova, size, IOMMU_WRITE))
                        return __FAIL(ops);

                if (ops->iova_to_phys(ops, iova + 42) != (iova + 42))
                        return __FAIL(ops);

                iova += SZ_16M;
                i++;
                i = find_next_bit(&cfg.pgsize_bitmap, BITS_PER_LONG, i);
        }

        free_io_pgtable_ops(ops);

        selftest_running = false;

        pr_info("self test ok\n");
        return 0;
}
subsys_initcall(arm_v7s_do_selftests);
#endif