ARM: 7432/1: use the new linux/sizes.h

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / arm / mm / dma-mapping.c

/*
 *  linux/arch/arm/mm/dma-mapping.c
 *
 *  Copyright (C) 2000-2004 Russell King
 *
 * 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.
 *
 *  DMA uncached mapping support.
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dma-contiguous.h>
#include <linux/highmem.h>
#include <linux/memblock.h>
#include <linux/slab.h>
#include <linux/iommu.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>

#include <asm/memory.h>
#include <asm/highmem.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/mach/arch.h>
#include <asm/dma-iommu.h>
#include <asm/mach/map.h>
#include <asm/system_info.h>
#include <asm/dma-contiguous.h>

#include "mm.h"

/*
 * The DMA API is built upon the notion of "buffer ownership".  A buffer
 * is either exclusively owned by the CPU (and therefore may be accessed
 * by it) or exclusively owned by the DMA device.  These helper functions
 * represent the transitions between these two ownership states.
 *
 * Note, however, that on later ARMs, this notion does not work due to
 * speculative prefetches.  We model our approach on the assumption that
 * the CPU does do speculative prefetches, which means we clean caches
 * before transfers and delay cache invalidation until transfer completion.
 *
 */
static void __dma_page_cpu_to_dev(struct page *, unsigned long,
                size_t, enum dma_data_direction);
static void __dma_page_dev_to_cpu(struct page *, unsigned long,
                size_t, enum dma_data_direction);

/**
 * arm_dma_map_page - map a portion of a page for streaming DMA
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @page: page that buffer resides in
 * @offset: offset into page for start of buffer
 * @size: size of buffer to map
 * @dir: DMA transfer direction
 *
 * Ensure that any data held in the cache is appropriately discarded
 * or written back.
 *
 * The device owns this memory once this call has completed.  The CPU
 * can regain ownership by calling dma_unmap_page().
 */
static dma_addr_t arm_dma_map_page(struct device *dev, struct page *page,
             unsigned long offset, size_t size, enum dma_data_direction dir,
             struct dma_attrs *attrs)
{
        if (!arch_is_coherent())
                __dma_page_cpu_to_dev(page, offset, size, dir);
        return pfn_to_dma(dev, page_to_pfn(page)) + offset;
}

/**
 * arm_dma_unmap_page - unmap a buffer previously mapped through dma_map_page()
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @handle: DMA address of buffer
 * @size: size of buffer (same as passed to dma_map_page)
 * @dir: DMA transfer direction (same as passed to dma_map_page)
 *
 * Unmap a page streaming mode DMA translation.  The handle and size
 * must match what was provided in the previous dma_map_page() call.
 * All other usages are undefined.
 *
 * After this call, reads by the CPU to the buffer are guaranteed to see
 * whatever the device wrote there.
 */
static void arm_dma_unmap_page(struct device *dev, dma_addr_t handle,
                size_t size, enum dma_data_direction dir,
                struct dma_attrs *attrs)
{
        if (!arch_is_coherent())
                __dma_page_dev_to_cpu(pfn_to_page(dma_to_pfn(dev, handle)),
                                      handle & ~PAGE_MASK, size, dir);
}

static void arm_dma_sync_single_for_cpu(struct device *dev,
                dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
        unsigned int offset = handle & (PAGE_SIZE - 1);
        struct page *page = pfn_to_page(dma_to_pfn(dev, handle-offset));
        if (!arch_is_coherent())
                __dma_page_dev_to_cpu(page, offset, size, dir);
}

static void arm_dma_sync_single_for_device(struct device *dev,
                dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
        unsigned int offset = handle & (PAGE_SIZE - 1);
        struct page *page = pfn_to_page(dma_to_pfn(dev, handle-offset));
        if (!arch_is_coherent())
                __dma_page_cpu_to_dev(page, offset, size, dir);
}

static int arm_dma_set_mask(struct device *dev, u64 dma_mask);

struct dma_map_ops arm_dma_ops = {
        .alloc                  = arm_dma_alloc,
        .free                   = arm_dma_free,
        .mmap                   = arm_dma_mmap,
        .map_page               = arm_dma_map_page,
        .unmap_page             = arm_dma_unmap_page,
        .map_sg                 = arm_dma_map_sg,
        .unmap_sg               = arm_dma_unmap_sg,
        .sync_single_for_cpu    = arm_dma_sync_single_for_cpu,
        .sync_single_for_device = arm_dma_sync_single_for_device,
        .sync_sg_for_cpu        = arm_dma_sync_sg_for_cpu,
        .sync_sg_for_device     = arm_dma_sync_sg_for_device,
        .set_dma_mask           = arm_dma_set_mask,
};
EXPORT_SYMBOL(arm_dma_ops);

static u64 get_coherent_dma_mask(struct device *dev)
{
        u64 mask = (u64)arm_dma_limit;

        if (dev) {
                mask = dev->coherent_dma_mask;

                /*
                 * Sanity check the DMA mask - it must be non-zero, and
                 * must be able to be satisfied by a DMA allocation.
                 */
                if (mask == 0) {
                        dev_warn(dev, "coherent DMA mask is unset\n");
                        return 0;
                }

                if ((~mask) & (u64)arm_dma_limit) {
                        dev_warn(dev, "coherent DMA mask %#llx is smaller "
                                 "than system GFP_DMA mask %#llx\n",
                                 mask, (u64)arm_dma_limit);
                        return 0;
                }
        }

        return mask;
}

static void __dma_clear_buffer(struct page *page, size_t size)
{
        void *ptr;
        /*
         * Ensure that the allocated pages are zeroed, and that any data
         * lurking in the kernel direct-mapped region is invalidated.
         */
        ptr = page_address(page);
        if (ptr) {
                memset(ptr, 0, size);
                dmac_flush_range(ptr, ptr + size);
                outer_flush_range(__pa(ptr), __pa(ptr) + size);
        }
}

/*
 * Allocate a DMA buffer for 'dev' of size 'size' using the
 * specified gfp mask.  Note that 'size' must be page aligned.
 */
static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
{
        unsigned long order = get_order(size);
        struct page *page, *p, *e;

        page = alloc_pages(gfp, order);
        if (!page)
                return NULL;

        /*
         * Now split the huge page and free the excess pages
         */
        split_page(page, order);
        for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
                __free_page(p);

        __dma_clear_buffer(page, size);

        return page;
}

/*
 * Free a DMA buffer.  'size' must be page aligned.
 */
static void __dma_free_buffer(struct page *page, size_t size)
{
        struct page *e = page + (size >> PAGE_SHIFT);

        while (page < e) {
                __free_page(page);
                page++;
        }
}

#ifdef CONFIG_MMU

#define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - consistent_base) >> PAGE_SHIFT)
#define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - consistent_base) >> PMD_SHIFT)

/*
 * These are the page tables (2MB each) covering uncached, DMA consistent allocations
 */
static pte_t **consistent_pte;

#define DEFAULT_CONSISTENT_DMA_SIZE SZ_2M

unsigned long consistent_base = CONSISTENT_END - DEFAULT_CONSISTENT_DMA_SIZE;

void __init init_consistent_dma_size(unsigned long size)
{
        unsigned long base = CONSISTENT_END - ALIGN(size, SZ_2M);

        BUG_ON(consistent_pte); /* Check we're called before DMA region init */
        BUG_ON(base < VMALLOC_END);

        /* Grow region to accommodate specified size  */
        if (base < consistent_base)
                consistent_base = base;
}

#include "vmregion.h"

static struct arm_vmregion_head consistent_head = {
        .vm_lock        = __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
        .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
        .vm_end         = CONSISTENT_END,
};

#ifdef CONFIG_HUGETLB_PAGE
#error ARM Coherent DMA allocator does not (yet) support huge TLB
#endif

/*
 * Initialise the consistent memory allocation.
 */
static int __init consistent_init(void)
{
        int ret = 0;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
        int i = 0;
        unsigned long base = consistent_base;
        unsigned long num_ptes = (CONSISTENT_END - base) >> PMD_SHIFT;

#ifndef CONFIG_ARM_DMA_USE_IOMMU
        if (cpu_architecture() >= CPU_ARCH_ARMv6)
                return 0;
#endif

        consistent_pte = kmalloc(num_ptes * sizeof(pte_t), GFP_KERNEL);
        if (!consistent_pte) {
                pr_err("%s: no memory\n", __func__);
                return -ENOMEM;
        }

        pr_debug("DMA memory: 0x%08lx - 0x%08lx:\n", base, CONSISTENT_END);
        consistent_head.vm_start = base;

        do {
                pgd = pgd_offset(&init_mm, base);

                pud = pud_alloc(&init_mm, pgd, base);
                if (!pud) {
                        pr_err("%s: no pud tables\n", __func__);
                        ret = -ENOMEM;
                        break;
                }

                pmd = pmd_alloc(&init_mm, pud, base);
                if (!pmd) {
                        pr_err("%s: no pmd tables\n", __func__);
                        ret = -ENOMEM;
                        break;
                }
                WARN_ON(!pmd_none(*pmd));

                pte = pte_alloc_kernel(pmd, base);
                if (!pte) {
                        pr_err("%s: no pte tables\n", __func__);
                        ret = -ENOMEM;
                        break;
                }

                consistent_pte[i++] = pte;
                base += PMD_SIZE;
        } while (base < CONSISTENT_END);

        return ret;
}
core_initcall(consistent_init);

static void *__alloc_from_contiguous(struct device *dev, size_t size,
                                     pgprot_t prot, struct page **ret_page);

static struct arm_vmregion_head coherent_head = {
        .vm_lock        = __SPIN_LOCK_UNLOCKED(&coherent_head.vm_lock),
        .vm_list        = LIST_HEAD_INIT(coherent_head.vm_list),
};

size_t coherent_pool_size = DEFAULT_CONSISTENT_DMA_SIZE / 8;

static int __init early_coherent_pool(char *p)
{
        coherent_pool_size = memparse(p, &p);
        return 0;
}
early_param("coherent_pool", early_coherent_pool);

/*
 * Initialise the coherent pool for atomic allocations.
 */
static int __init coherent_init(void)
{
        pgprot_t prot = pgprot_dmacoherent(pgprot_kernel);
        size_t size = coherent_pool_size;
        struct page *page;
        void *ptr;

        if (cpu_architecture() < CPU_ARCH_ARMv6)
                return 0;

        ptr = __alloc_from_contiguous(NULL, size, prot, &page);
        if (ptr) {
                coherent_head.vm_start = (unsigned long) ptr;
                coherent_head.vm_end = (unsigned long) ptr + size;
                printk(KERN_INFO "DMA: preallocated %u KiB pool for atomic coherent allocations\n",
                       (unsigned)size / 1024);
                return 0;
        }
        printk(KERN_ERR "DMA: failed to allocate %u KiB pool for atomic coherent allocation\n",
               (unsigned)size / 1024);
        return -ENOMEM;
}
/*
 * CMA is activated by core_initcall, so we must be called after it.
 */
postcore_initcall(coherent_init);

struct dma_contig_early_reserve {
        phys_addr_t base;
        unsigned long size;
};

static struct dma_contig_early_reserve dma_mmu_remap[MAX_CMA_AREAS] __initdata;

static int dma_mmu_remap_num __initdata;

void __init dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
{
        dma_mmu_remap[dma_mmu_remap_num].base = base;
        dma_mmu_remap[dma_mmu_remap_num].size = size;
        dma_mmu_remap_num++;
}

void __init dma_contiguous_remap(void)
{
        int i;
        for (i = 0; i < dma_mmu_remap_num; i++) {
                phys_addr_t start = dma_mmu_remap[i].base;
                phys_addr_t end = start + dma_mmu_remap[i].size;
                struct map_desc map;
                unsigned long addr;

                if (end > arm_lowmem_limit)
                        end = arm_lowmem_limit;
                if (start >= end)
                        return;

                map.pfn = __phys_to_pfn(start);
                map.virtual = __phys_to_virt(start);
                map.length = end - start;
                map.type = MT_MEMORY_DMA_READY;

                /*
                 * Clear previous low-memory mapping
                 */
                for (addr = __phys_to_virt(start); addr < __phys_to_virt(end);
                     addr += PMD_SIZE)
                        pmd_clear(pmd_off_k(addr));

                iotable_init(&map, 1);
        }
}

static void *
__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
        const void *caller)
{
        struct arm_vmregion *c;
        size_t align;
        int bit;

        if (!consistent_pte) {
                pr_err("%s: not initialised\n", __func__);
                dump_stack();
                return NULL;
        }

        /*
         * Align the virtual region allocation - maximum alignment is
         * a section size, minimum is a page size.  This helps reduce
         * fragmentation of the DMA space, and also prevents allocations
         * smaller than a section from crossing a section boundary.
         */
        bit = fls(size - 1);
        if (bit > SECTION_SHIFT)
                bit = SECTION_SHIFT;
        align = 1 << bit;

        /*
         * Allocate a virtual address in the consistent mapping region.
         */
        c = arm_vmregion_alloc(&consistent_head, align, size,
                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM), caller);
        if (c) {
                pte_t *pte;
                int idx = CONSISTENT_PTE_INDEX(c->vm_start);
                u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);

                pte = consistent_pte[idx] + off;
                c->priv = page;

                do {
                        BUG_ON(!pte_none(*pte));

                        set_pte_ext(pte, mk_pte(page, prot), 0);
                        page++;
                        pte++;
                        off++;
                        if (off >= PTRS_PER_PTE) {
                                off = 0;
                                pte = consistent_pte[++idx];
                        }
                } while (size -= PAGE_SIZE);

                dsb();

                return (void *)c->vm_start;
        }
        return NULL;
}

static void __dma_free_remap(void *cpu_addr, size_t size)
{
        struct arm_vmregion *c;
        unsigned long addr;
        pte_t *ptep;
        int idx;
        u32 off;

        c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
        if (!c) {
                pr_err("%s: trying to free invalid coherent area: %p\n",
                       __func__, cpu_addr);
                dump_stack();
                return;
        }

        if ((c->vm_end - c->vm_start) != size) {
                pr_err("%s: freeing wrong coherent size (%ld != %d)\n",
                       __func__, c->vm_end - c->vm_start, size);
                dump_stack();
                size = c->vm_end - c->vm_start;
        }

        idx = CONSISTENT_PTE_INDEX(c->vm_start);
        off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
        ptep = consistent_pte[idx] + off;
        addr = c->vm_start;
        do {
                pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);

                ptep++;
                addr += PAGE_SIZE;
                off++;
                if (off >= PTRS_PER_PTE) {
                        off = 0;
                        ptep = consistent_pte[++idx];
                }

                if (pte_none(pte) || !pte_present(pte))
                        pr_crit("%s: bad page in kernel page table\n",
                                __func__);
        } while (size -= PAGE_SIZE);

        flush_tlb_kernel_range(c->vm_start, c->vm_end);

        arm_vmregion_free(&consistent_head, c);
}

static int __dma_update_pte(pte_t *pte, pgtable_t token, unsigned long addr,
                            void *data)
{
        struct page *page = virt_to_page(addr);
        pgprot_t prot = *(pgprot_t *)data;

        set_pte_ext(pte, mk_pte(page, prot), 0);
        return 0;
}

static void __dma_remap(struct page *page, size_t size, pgprot_t prot)
{
        unsigned long start = (unsigned long) page_address(page);
        unsigned end = start + size;

        apply_to_page_range(&init_mm, start, size, __dma_update_pte, &prot);
        dsb();
        flush_tlb_kernel_range(start, end);
}

static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
                                 pgprot_t prot, struct page **ret_page,
                                 const void *caller)
{
        struct page *page;
        void *ptr;
        page = __dma_alloc_buffer(dev, size, gfp);
        if (!page)
                return NULL;

        ptr = __dma_alloc_remap(page, size, gfp, prot, caller);
        if (!ptr) {
                __dma_free_buffer(page, size);
                return NULL;
        }

        *ret_page = page;
        return ptr;
}

static void *__alloc_from_pool(struct device *dev, size_t size,
                               struct page **ret_page, const void *caller)
{
        struct arm_vmregion *c;
        size_t align;

        if (!coherent_head.vm_start) {
                printk(KERN_ERR "%s: coherent pool not initialised!\n",
                       __func__);
                dump_stack();
                return NULL;
        }

        /*
         * Align the region allocation - allocations from pool are rather
         * small, so align them to their order in pages, minimum is a page
         * size. This helps reduce fragmentation of the DMA space.
         */
        align = PAGE_SIZE << get_order(size);
        c = arm_vmregion_alloc(&coherent_head, align, size, 0, caller);
        if (c) {
                void *ptr = (void *)c->vm_start;
                struct page *page = virt_to_page(ptr);
                *ret_page = page;
                return ptr;
        }
        return NULL;
}

static int __free_from_pool(void *cpu_addr, size_t size)
{
        unsigned long start = (unsigned long)cpu_addr;
        unsigned long end = start + size;
        struct arm_vmregion *c;

        if (start < coherent_head.vm_start || end > coherent_head.vm_end)
                return 0;

        c = arm_vmregion_find_remove(&coherent_head, (unsigned long)start);

        if ((c->vm_end - c->vm_start) != size) {
                printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
                       __func__, c->vm_end - c->vm_start, size);
                dump_stack();
                size = c->vm_end - c->vm_start;
        }

        arm_vmregion_free(&coherent_head, c);
        return 1;
}

static void *__alloc_from_contiguous(struct device *dev, size_t size,
                                     pgprot_t prot, struct page **ret_page)
{
        unsigned long order = get_order(size);
        size_t count = size >> PAGE_SHIFT;
        struct page *page;

        page = dma_alloc_from_contiguous(dev, count, order);
        if (!page)
                return NULL;

        __dma_clear_buffer(page, size);
        __dma_remap(page, size, prot);

        *ret_page = page;
        return page_address(page);
}

static void __free_from_contiguous(struct device *dev, struct page *page,
                                   size_t size)
{
        __dma_remap(page, size, pgprot_kernel);
        dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
}

static inline pgprot_t __get_dma_pgprot(struct dma_attrs *attrs, pgprot_t prot)
{
        prot = dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs) ?
                            pgprot_writecombine(prot) :
                            pgprot_dmacoherent(prot);
        return prot;
}

#define nommu() 0

#else   /* !CONFIG_MMU */

#define nommu() 1

#define __get_dma_pgprot(attrs, prot)   __pgprot(0)
#define __alloc_remap_buffer(dev, size, gfp, prot, ret, c)      NULL
#define __alloc_from_pool(dev, size, ret_page, c)               NULL
#define __alloc_from_contiguous(dev, size, prot, ret)           NULL
#define __free_from_pool(cpu_addr, size)                        0
#define __free_from_contiguous(dev, page, size)                 do { } while (0)
#define __dma_free_remap(cpu_addr, size)                        do { } while (0)

#endif  /* CONFIG_MMU */

static void *__alloc_simple_buffer(struct device *dev, size_t size, gfp_t gfp,
                                   struct page **ret_page)
{
        struct page *page;
        page = __dma_alloc_buffer(dev, size, gfp);
        if (!page)
                return NULL;

        *ret_page = page;
        return page_address(page);
}



static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
                         gfp_t gfp, pgprot_t prot, const void *caller)
{
        u64 mask = get_coherent_dma_mask(dev);
        struct page *page;
        void *addr;

#ifdef CONFIG_DMA_API_DEBUG
        u64 limit = (mask + 1) & ~mask;
        if (limit && size >= limit) {
                dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
                        size, mask);
                return NULL;
        }
#endif

        if (!mask)
                return NULL;

        if (mask < 0xffffffffULL)
                gfp |= GFP_DMA;

        /*
         * Following is a work-around (a.k.a. hack) to prevent pages
         * with __GFP_COMP being passed to split_page() which cannot
         * handle them.  The real problem is that this flag probably
         * should be 0 on ARM as it is not supported on this
         * platform; see CONFIG_HUGETLBFS.
         */
        gfp &= ~(__GFP_COMP);

        *handle = DMA_ERROR_CODE;
        size = PAGE_ALIGN(size);

        if (arch_is_coherent() || nommu())
                addr = __alloc_simple_buffer(dev, size, gfp, &page);
        else if (cpu_architecture() < CPU_ARCH_ARMv6)
                addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller);
        else if (gfp & GFP_ATOMIC)
                addr = __alloc_from_pool(dev, size, &page, caller);
        else
                addr = __alloc_from_contiguous(dev, size, prot, &page);

        if (addr)
                *handle = pfn_to_dma(dev, page_to_pfn(page));

        return addr;
}

/*
 * Allocate DMA-coherent memory space and return both the kernel remapped
 * virtual and bus address for that space.
 */
void *arm_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
                    gfp_t gfp, struct dma_attrs *attrs)
{
        pgprot_t prot = __get_dma_pgprot(attrs, pgprot_kernel);
        void *memory;

        if (dma_alloc_from_coherent(dev, size, handle, &memory))
                return memory;

        return __dma_alloc(dev, size, handle, gfp, prot,
                           __builtin_return_address(0));
}

/*
 * Create userspace mapping for the DMA-coherent memory.
 */
int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
                 void *cpu_addr, dma_addr_t dma_addr, size_t size,
                 struct dma_attrs *attrs)
{
        int ret = -ENXIO;
#ifdef CONFIG_MMU
        unsigned long pfn = dma_to_pfn(dev, dma_addr);
        vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);

        if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
                return ret;

        ret = remap_pfn_range(vma, vma->vm_start,
                              pfn + vma->vm_pgoff,
                              vma->vm_end - vma->vm_start,
                              vma->vm_page_prot);
#endif  /* CONFIG_MMU */

        return ret;
}

/*
 * Free a buffer as defined by the above mapping.
 */
void arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
                  dma_addr_t handle, struct dma_attrs *attrs)
{
        struct page *page = pfn_to_page(dma_to_pfn(dev, handle));

        if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
                return;

        size = PAGE_ALIGN(size);

        if (arch_is_coherent() || nommu()) {
                __dma_free_buffer(page, size);
        } else if (cpu_architecture() < CPU_ARCH_ARMv6) {
                __dma_free_remap(cpu_addr, size);
                __dma_free_buffer(page, size);
        } else {
                if (__free_from_pool(cpu_addr, size))
                        return;
                /*
                 * Non-atomic allocations cannot be freed with IRQs disabled
                 */
                WARN_ON(irqs_disabled());
                __free_from_contiguous(dev, page, size);
        }
}

static void dma_cache_maint_page(struct page *page, unsigned long offset,
        size_t size, enum dma_data_direction dir,
        void (*op)(const void *, size_t, int))
{
        /*
         * A single sg entry may refer to multiple physically contiguous
         * pages.  But we still need to process highmem pages individually.
         * If highmem is not configured then the bulk of this loop gets
         * optimized out.
         */
        size_t left = size;
        do {
                size_t len = left;
                void *vaddr;

                if (PageHighMem(page)) {
                        if (len + offset > PAGE_SIZE) {
                                if (offset >= PAGE_SIZE) {
                                        page += offset / PAGE_SIZE;
                                        offset %= PAGE_SIZE;
                                }
                                len = PAGE_SIZE - offset;
                        }
                        vaddr = kmap_high_get(page);
                        if (vaddr) {
                                vaddr += offset;
                                op(vaddr, len, dir);
                                kunmap_high(page);
                        } else if (cache_is_vipt()) {
                                /* unmapped pages might still be cached */
                                vaddr = kmap_atomic(page);
                                op(vaddr + offset, len, dir);
                                kunmap_atomic(vaddr);
                        }
                } else {
                        vaddr = page_address(page) + offset;
                        op(vaddr, len, dir);
                }
                offset = 0;
                page++;
                left -= len;
        } while (left);
}

/*
 * Make an area consistent for devices.
 * Note: Drivers should NOT use this function directly, as it will break
 * platforms with CONFIG_DMABOUNCE.
 * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
 */
static void __dma_page_cpu_to_dev(struct page *page, unsigned long off,
        size_t size, enum dma_data_direction dir)
{
        unsigned long paddr;

        dma_cache_maint_page(page, off, size, dir, dmac_map_area);

        paddr = page_to_phys(page) + off;
        if (dir == DMA_FROM_DEVICE) {
                outer_inv_range(paddr, paddr + size);
        } else {
                outer_clean_range(paddr, paddr + size);
        }
        /* FIXME: non-speculating: flush on bidirectional mappings? */
}

static void __dma_page_dev_to_cpu(struct page *page, unsigned long off,
        size_t size, enum dma_data_direction dir)
{
        unsigned long paddr = page_to_phys(page) + off;

        /* FIXME: non-speculating: not required */
        /* don't bother invalidating if DMA to device */
        if (dir != DMA_TO_DEVICE)
                outer_inv_range(paddr, paddr + size);

        dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);

        /*
         * Mark the D-cache clean for this page to avoid extra flushing.
         */
        if (dir != DMA_TO_DEVICE && off == 0 && size >= PAGE_SIZE)
                set_bit(PG_dcache_clean, &page->flags);
}

/**
 * arm_dma_map_sg - map a set of SG buffers for streaming mode DMA
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @sg: list of buffers
 * @nents: number of buffers to map
 * @dir: DMA transfer direction
 *
 * Map a set of buffers described by scatterlist in streaming mode for DMA.
 * This is the scatter-gather version of the dma_map_single interface.
 * Here the scatter gather list elements are each tagged with the
 * appropriate dma address and length.  They are obtained via
 * sg_dma_{address,length}.
 *
 * Device ownership issues as mentioned for dma_map_single are the same
 * here.
 */
int arm_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
                enum dma_data_direction dir, struct dma_attrs *attrs)
{
        struct dma_map_ops *ops = get_dma_ops(dev);
        struct scatterlist *s;
        int i, j;

        for_each_sg(sg, s, nents, i) {
#ifdef CONFIG_NEED_SG_DMA_LENGTH
                s->dma_length = s->length;
#endif
                s->dma_address = ops->map_page(dev, sg_page(s), s->offset,
                                                s->length, dir, attrs);
                if (dma_mapping_error(dev, s->dma_address))
                        goto bad_mapping;
        }
        return nents;

 bad_mapping:
        for_each_sg(sg, s, i, j)
                ops->unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir, attrs);
        return 0;
}

/**
 * arm_dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @sg: list of buffers
 * @nents: number of buffers to unmap (same as was passed to dma_map_sg)
 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 *
 * Unmap a set of streaming mode DMA translations.  Again, CPU access
 * rules concerning calls here are the same as for dma_unmap_single().
 */
void arm_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
                enum dma_data_direction dir, struct dma_attrs *attrs)
{
        struct dma_map_ops *ops = get_dma_ops(dev);
        struct scatterlist *s;

        int i;

        for_each_sg(sg, s, nents, i)
                ops->unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir, attrs);
}

/**
 * arm_dma_sync_sg_for_cpu
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @sg: list of buffers
 * @nents: number of buffers to map (returned from dma_map_sg)
 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 */
void arm_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
                        int nents, enum dma_data_direction dir)
{
        struct dma_map_ops *ops = get_dma_ops(dev);
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i)
                ops->sync_single_for_cpu(dev, sg_dma_address(s), s->length,
                                         dir);
}

/**
 * arm_dma_sync_sg_for_device
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @sg: list of buffers
 * @nents: number of buffers to map (returned from dma_map_sg)
 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 */
void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
                        int nents, enum dma_data_direction dir)
{
        struct dma_map_ops *ops = get_dma_ops(dev);
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i)
                ops->sync_single_for_device(dev, sg_dma_address(s), s->length,
                                            dir);
}

/*
 * Return whether the given device DMA address mask can be supported
 * properly.  For example, if your device can only drive the low 24-bits
 * during bus mastering, then you would pass 0x00ffffff as the mask
 * to this function.
 */
int dma_supported(struct device *dev, u64 mask)
{
        if (mask < (u64)arm_dma_limit)
                return 0;
        return 1;
}
EXPORT_SYMBOL(dma_supported);

static int arm_dma_set_mask(struct device *dev, u64 dma_mask)
{
        if (!dev->dma_mask || !dma_supported(dev, dma_mask))
                return -EIO;

        *dev->dma_mask = dma_mask;

        return 0;
}

#define PREALLOC_DMA_DEBUG_ENTRIES      4096

static int __init dma_debug_do_init(void)
{
#ifdef CONFIG_MMU
        arm_vmregion_create_proc("dma-mappings", &consistent_head);
#endif
        dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
        return 0;
}
fs_initcall(dma_debug_do_init);

#ifdef CONFIG_ARM_DMA_USE_IOMMU

/* IOMMU */

static inline dma_addr_t __alloc_iova(struct dma_iommu_mapping *mapping,
                                      size_t size)
{
        unsigned int order = get_order(size);
        unsigned int align = 0;
        unsigned int count, start;
        unsigned long flags;

        count = ((PAGE_ALIGN(size) >> PAGE_SHIFT) +
                 (1 << mapping->order) - 1) >> mapping->order;

        if (order > mapping->order)
                align = (1 << (order - mapping->order)) - 1;

        spin_lock_irqsave(&mapping->lock, flags);
        start = bitmap_find_next_zero_area(mapping->bitmap, mapping->bits, 0,
                                           count, align);
        if (start > mapping->bits) {
                spin_unlock_irqrestore(&mapping->lock, flags);
                return DMA_ERROR_CODE;
        }

        bitmap_set(mapping->bitmap, start, count);
        spin_unlock_irqrestore(&mapping->lock, flags);

        return mapping->base + (start << (mapping->order + PAGE_SHIFT));
}

static inline void __free_iova(struct dma_iommu_mapping *mapping,
                               dma_addr_t addr, size_t size)
{
        unsigned int start = (addr - mapping->base) >>
                             (mapping->order + PAGE_SHIFT);
        unsigned int count = ((size >> PAGE_SHIFT) +
                              (1 << mapping->order) - 1) >> mapping->order;
        unsigned long flags;

        spin_lock_irqsave(&mapping->lock, flags);
        bitmap_clear(mapping->bitmap, start, count);
        spin_unlock_irqrestore(&mapping->lock, flags);
}

static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
{
        struct page **pages;
        int count = size >> PAGE_SHIFT;
        int array_size = count * sizeof(struct page *);
        int i = 0;

        if (array_size <= PAGE_SIZE)
                pages = kzalloc(array_size, gfp);
        else
                pages = vzalloc(array_size);
        if (!pages)
                return NULL;

        while (count) {
                int j, order = __ffs(count);

                pages[i] = alloc_pages(gfp | __GFP_NOWARN, order);
                while (!pages[i] && order)
                        pages[i] = alloc_pages(gfp | __GFP_NOWARN, --order);
                if (!pages[i])
                        goto error;

                if (order)
                        split_page(pages[i], order);
                j = 1 << order;
                while (--j)
                        pages[i + j] = pages[i] + j;

                __dma_clear_buffer(pages[i], PAGE_SIZE << order);
                i += 1 << order;
                count -= 1 << order;
        }

        return pages;
error:
        while (--i)
                if (pages[i])
                        __free_pages(pages[i], 0);
        if (array_size < PAGE_SIZE)
                kfree(pages);
        else
                vfree(pages);
        return NULL;
}

static int __iommu_free_buffer(struct device *dev, struct page **pages, size_t size)
{
        int count = size >> PAGE_SHIFT;
        int array_size = count * sizeof(struct page *);
        int i;
        for (i = 0; i < count; i++)
                if (pages[i])
                        __free_pages(pages[i], 0);
        if (array_size < PAGE_SIZE)
                kfree(pages);
        else
                vfree(pages);
        return 0;
}

/*
 * Create a CPU mapping for a specified pages
 */
static void *
__iommu_alloc_remap(struct page **pages, size_t size, gfp_t gfp, pgprot_t prot)
{
        struct arm_vmregion *c;
        size_t align;
        size_t count = size >> PAGE_SHIFT;
        int bit;

        if (!consistent_pte[0]) {
                pr_err("%s: not initialised\n", __func__);
                dump_stack();
                return NULL;
        }

        /*
         * Align the virtual region allocation - maximum alignment is
         * a section size, minimum is a page size.  This helps reduce
         * fragmentation of the DMA space, and also prevents allocations
         * smaller than a section from crossing a section boundary.
         */
        bit = fls(size - 1);
        if (bit > SECTION_SHIFT)
                bit = SECTION_SHIFT;
        align = 1 << bit;

        /*
         * Allocate a virtual address in the consistent mapping region.
         */
        c = arm_vmregion_alloc(&consistent_head, align, size,
                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM), NULL);
        if (c) {
                pte_t *pte;
                int idx = CONSISTENT_PTE_INDEX(c->vm_start);
                int i = 0;
                u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);

                pte = consistent_pte[idx] + off;
                c->priv = pages;

                do {
                        BUG_ON(!pte_none(*pte));

                        set_pte_ext(pte, mk_pte(pages[i], prot), 0);
                        pte++;
                        off++;
                        i++;
                        if (off >= PTRS_PER_PTE) {
                                off = 0;
                                pte = consistent_pte[++idx];
                        }
                } while (i < count);

                dsb();

                return (void *)c->vm_start;
        }
        return NULL;
}

/*
 * Create a mapping in device IO address space for specified pages
 */
static dma_addr_t
__iommu_create_mapping(struct device *dev, struct page **pages, size_t size)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
        dma_addr_t dma_addr, iova;
        int i, ret = DMA_ERROR_CODE;

        dma_addr = __alloc_iova(mapping, size);
        if (dma_addr == DMA_ERROR_CODE)
                return dma_addr;

        iova = dma_addr;
        for (i = 0; i < count; ) {
                unsigned int next_pfn = page_to_pfn(pages[i]) + 1;
                phys_addr_t phys = page_to_phys(pages[i]);
                unsigned int len, j;

                for (j = i + 1; j < count; j++, next_pfn++)
                        if (page_to_pfn(pages[j]) != next_pfn)
                                break;

                len = (j - i) << PAGE_SHIFT;
                ret = iommu_map(mapping->domain, iova, phys, len, 0);
                if (ret < 0)
                        goto fail;
                iova += len;
                i = j;
        }
        return dma_addr;
fail:
        iommu_unmap(mapping->domain, dma_addr, iova-dma_addr);
        __free_iova(mapping, dma_addr, size);
        return DMA_ERROR_CODE;
}

static int __iommu_remove_mapping(struct device *dev, dma_addr_t iova, size_t size)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;

        /*
         * add optional in-page offset from iova to size and align
         * result to page size
         */
        size = PAGE_ALIGN((iova & ~PAGE_MASK) + size);
        iova &= PAGE_MASK;

        iommu_unmap(mapping->domain, iova, size);
        __free_iova(mapping, iova, size);
        return 0;
}

static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
            dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs)
{
        pgprot_t prot = __get_dma_pgprot(attrs, pgprot_kernel);
        struct page **pages;
        void *addr = NULL;

        *handle = DMA_ERROR_CODE;
        size = PAGE_ALIGN(size);

        pages = __iommu_alloc_buffer(dev, size, gfp);
        if (!pages)
                return NULL;

        *handle = __iommu_create_mapping(dev, pages, size);
        if (*handle == DMA_ERROR_CODE)
                goto err_buffer;

        addr = __iommu_alloc_remap(pages, size, gfp, prot);
        if (!addr)
                goto err_mapping;

        return addr;

err_mapping:
        __iommu_remove_mapping(dev, *handle, size);
err_buffer:
        __iommu_free_buffer(dev, pages, size);
        return NULL;
}

static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
                    void *cpu_addr, dma_addr_t dma_addr, size_t size,
                    struct dma_attrs *attrs)
{
        struct arm_vmregion *c;

        vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
        c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);

        if (c) {
                struct page **pages = c->priv;

                unsigned long uaddr = vma->vm_start;
                unsigned long usize = vma->vm_end - vma->vm_start;
                int i = 0;

                do {
                        int ret;

                        ret = vm_insert_page(vma, uaddr, pages[i++]);
                        if (ret) {
                                pr_err("Remapping memory, error: %d\n", ret);
                                return ret;
                        }

                        uaddr += PAGE_SIZE;
                        usize -= PAGE_SIZE;
                } while (usize > 0);
        }
        return 0;
}

/*
 * free a page as defined by the above mapping.
 * Must not be called with IRQs disabled.
 */
void arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
                          dma_addr_t handle, struct dma_attrs *attrs)
{
        struct arm_vmregion *c;
        size = PAGE_ALIGN(size);

        c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
        if (c) {
                struct page **pages = c->priv;
                __dma_free_remap(cpu_addr, size);
                __iommu_remove_mapping(dev, handle, size);
                __iommu_free_buffer(dev, pages, size);
        }
}

/*
 * Map a part of the scatter-gather list into contiguous io address space
 */
static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
                          size_t size, dma_addr_t *handle,
                          enum dma_data_direction dir)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        dma_addr_t iova, iova_base;
        int ret = 0;
        unsigned int count;
        struct scatterlist *s;

        size = PAGE_ALIGN(size);
        *handle = DMA_ERROR_CODE;

        iova_base = iova = __alloc_iova(mapping, size);
        if (iova == DMA_ERROR_CODE)
                return -ENOMEM;

        for (count = 0, s = sg; count < (size >> PAGE_SHIFT); s = sg_next(s)) {
                phys_addr_t phys = page_to_phys(sg_page(s));
                unsigned int len = PAGE_ALIGN(s->offset + s->length);

                if (!arch_is_coherent())
                        __dma_page_cpu_to_dev(sg_page(s), s->offset, s->length, dir);

                ret = iommu_map(mapping->domain, iova, phys, len, 0);
                if (ret < 0)
                        goto fail;
                count += len >> PAGE_SHIFT;
                iova += len;
        }
        *handle = iova_base;

        return 0;
fail:
        iommu_unmap(mapping->domain, iova_base, count * PAGE_SIZE);
        __free_iova(mapping, iova_base, size);
        return ret;
}

/**
 * arm_iommu_map_sg - map a set of SG buffers for streaming mode DMA
 * @dev: valid struct device pointer
 * @sg: list of buffers
 * @nents: number of buffers to map
 * @dir: DMA transfer direction
 *
 * Map a set of buffers described by scatterlist in streaming mode for DMA.
 * The scatter gather list elements are merged together (if possible) and
 * tagged with the appropriate dma address and length. They are obtained via
 * sg_dma_{address,length}.
 */
int arm_iommu_map_sg(struct device *dev, struct scatterlist *sg, int nents,
                     enum dma_data_direction dir, struct dma_attrs *attrs)
{
        struct scatterlist *s = sg, *dma = sg, *start = sg;
        int i, count = 0;
        unsigned int offset = s->offset;
        unsigned int size = s->offset + s->length;
        unsigned int max = dma_get_max_seg_size(dev);

        for (i = 1; i < nents; i++) {
                s = sg_next(s);

                s->dma_address = DMA_ERROR_CODE;
                s->dma_length = 0;

                if (s->offset || (size & ~PAGE_MASK) || size + s->length > max) {
                        if (__map_sg_chunk(dev, start, size, &dma->dma_address,
                            dir) < 0)
                                goto bad_mapping;

                        dma->dma_address += offset;
                        dma->dma_length = size - offset;

                        size = offset = s->offset;
                        start = s;
                        dma = sg_next(dma);
                        count += 1;
                }
                size += s->length;
        }
        if (__map_sg_chunk(dev, start, size, &dma->dma_address, dir) < 0)
                goto bad_mapping;

        dma->dma_address += offset;
        dma->dma_length = size - offset;

        return count+1;

bad_mapping:
        for_each_sg(sg, s, count, i)
                __iommu_remove_mapping(dev, sg_dma_address(s), sg_dma_len(s));
        return 0;
}

/**
 * arm_iommu_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
 * @dev: valid struct device pointer
 * @sg: list of buffers
 * @nents: number of buffers to unmap (same as was passed to dma_map_sg)
 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 *
 * Unmap a set of streaming mode DMA translations.  Again, CPU access
 * rules concerning calls here are the same as for dma_unmap_single().
 */
void arm_iommu_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
                        enum dma_data_direction dir, struct dma_attrs *attrs)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i) {
                if (sg_dma_len(s))
                        __iommu_remove_mapping(dev, sg_dma_address(s),
                                               sg_dma_len(s));
                if (!arch_is_coherent())
                        __dma_page_dev_to_cpu(sg_page(s), s->offset,
                                              s->length, dir);
        }
}

/**
 * arm_iommu_sync_sg_for_cpu
 * @dev: valid struct device pointer
 * @sg: list of buffers
 * @nents: number of buffers to map (returned from dma_map_sg)
 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 */
void arm_iommu_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
                        int nents, enum dma_data_direction dir)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i)
                if (!arch_is_coherent())
                        __dma_page_dev_to_cpu(sg_page(s), s->offset, s->length, dir);

}

/**
 * arm_iommu_sync_sg_for_device
 * @dev: valid struct device pointer
 * @sg: list of buffers
 * @nents: number of buffers to map (returned from dma_map_sg)
 * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 */
void arm_iommu_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
                        int nents, enum dma_data_direction dir)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sg, s, nents, i)
                if (!arch_is_coherent())
                        __dma_page_cpu_to_dev(sg_page(s), s->offset, s->length, dir);
}


/**
 * arm_iommu_map_page
 * @dev: valid struct device pointer
 * @page: page that buffer resides in
 * @offset: offset into page for start of buffer
 * @size: size of buffer to map
 * @dir: DMA transfer direction
 *
 * IOMMU aware version of arm_dma_map_page()
 */
static dma_addr_t arm_iommu_map_page(struct device *dev, struct page *page,
             unsigned long offset, size_t size, enum dma_data_direction dir,
             struct dma_attrs *attrs)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        dma_addr_t dma_addr;
        int ret, len = PAGE_ALIGN(size + offset);

        if (!arch_is_coherent())
                __dma_page_cpu_to_dev(page, offset, size, dir);

        dma_addr = __alloc_iova(mapping, len);
        if (dma_addr == DMA_ERROR_CODE)
                return dma_addr;

        ret = iommu_map(mapping->domain, dma_addr, page_to_phys(page), len, 0);
        if (ret < 0)
                goto fail;

        return dma_addr + offset;
fail:
        __free_iova(mapping, dma_addr, len);
        return DMA_ERROR_CODE;
}

/**
 * arm_iommu_unmap_page
 * @dev: valid struct device pointer
 * @handle: DMA address of buffer
 * @size: size of buffer (same as passed to dma_map_page)
 * @dir: DMA transfer direction (same as passed to dma_map_page)
 *
 * IOMMU aware version of arm_dma_unmap_page()
 */
static void arm_iommu_unmap_page(struct device *dev, dma_addr_t handle,
                size_t size, enum dma_data_direction dir,
                struct dma_attrs *attrs)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        dma_addr_t iova = handle & PAGE_MASK;
        struct page *page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
        int offset = handle & ~PAGE_MASK;
        int len = PAGE_ALIGN(size + offset);

        if (!iova)
                return;

        if (!arch_is_coherent())
                __dma_page_dev_to_cpu(page, offset, size, dir);

        iommu_unmap(mapping->domain, iova, len);
        __free_iova(mapping, iova, len);
}

static void arm_iommu_sync_single_for_cpu(struct device *dev,
                dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        dma_addr_t iova = handle & PAGE_MASK;
        struct page *page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
        unsigned int offset = handle & ~PAGE_MASK;

        if (!iova)
                return;

        if (!arch_is_coherent())
                __dma_page_dev_to_cpu(page, offset, size, dir);
}

static void arm_iommu_sync_single_for_device(struct device *dev,
                dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        dma_addr_t iova = handle & PAGE_MASK;
        struct page *page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
        unsigned int offset = handle & ~PAGE_MASK;

        if (!iova)
                return;

        __dma_page_cpu_to_dev(page, offset, size, dir);
}

struct dma_map_ops iommu_ops = {
        .alloc          = arm_iommu_alloc_attrs,
        .free           = arm_iommu_free_attrs,
        .mmap           = arm_iommu_mmap_attrs,

        .map_page               = arm_iommu_map_page,
        .unmap_page             = arm_iommu_unmap_page,
        .sync_single_for_cpu    = arm_iommu_sync_single_for_cpu,
        .sync_single_for_device = arm_iommu_sync_single_for_device,

        .map_sg                 = arm_iommu_map_sg,
        .unmap_sg               = arm_iommu_unmap_sg,
        .sync_sg_for_cpu        = arm_iommu_sync_sg_for_cpu,
        .sync_sg_for_device     = arm_iommu_sync_sg_for_device,
};

/**
 * arm_iommu_create_mapping
 * @bus: pointer to the bus holding the client device (for IOMMU calls)
 * @base: start address of the valid IO address space
 * @size: size of the valid IO address space
 * @order: accuracy of the IO addresses allocations
 *
 * Creates a mapping structure which holds information about used/unused
 * IO address ranges, which is required to perform memory allocation and
 * mapping with IOMMU aware functions.
 *
 * The client device need to be attached to the mapping with
 * arm_iommu_attach_device function.
 */
struct dma_iommu_mapping *
arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size,
                         int order)
{
        unsigned int count = size >> (PAGE_SHIFT + order);
        unsigned int bitmap_size = BITS_TO_LONGS(count) * sizeof(long);
        struct dma_iommu_mapping *mapping;
        int err = -ENOMEM;

        if (!count)
                return ERR_PTR(-EINVAL);

        mapping = kzalloc(sizeof(struct dma_iommu_mapping), GFP_KERNEL);
        if (!mapping)
                goto err;

        mapping->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
        if (!mapping->bitmap)
                goto err2;

        mapping->base = base;
        mapping->bits = BITS_PER_BYTE * bitmap_size;
        mapping->order = order;
        spin_lock_init(&mapping->lock);

        mapping->domain = iommu_domain_alloc(bus);
        if (!mapping->domain)
                goto err3;

        kref_init(&mapping->kref);
        return mapping;
err3:
        kfree(mapping->bitmap);
err2:
        kfree(mapping);
err:
        return ERR_PTR(err);
}

static void release_iommu_mapping(struct kref *kref)
{
        struct dma_iommu_mapping *mapping =
                container_of(kref, struct dma_iommu_mapping, kref);

        iommu_domain_free(mapping->domain);
        kfree(mapping->bitmap);
        kfree(mapping);
}

void arm_iommu_release_mapping(struct dma_iommu_mapping *mapping)
{
        if (mapping)
                kref_put(&mapping->kref, release_iommu_mapping);
}

/**
 * arm_iommu_attach_device
 * @dev: valid struct device pointer
 * @mapping: io address space mapping structure (returned from
 *      arm_iommu_create_mapping)
 *
 * Attaches specified io address space mapping to the provided device,
 * this replaces the dma operations (dma_map_ops pointer) with the
 * IOMMU aware version. More than one client might be attached to
 * the same io address space mapping.
 */
int arm_iommu_attach_device(struct device *dev,
                            struct dma_iommu_mapping *mapping)
{
        int err;

        err = iommu_attach_device(mapping->domain, dev);
        if (err)
                return err;

        kref_get(&mapping->kref);
        dev->archdata.mapping = mapping;
        set_dma_ops(dev, &iommu_ops);

        pr_info("Attached IOMMU controller to %s device.\n", dev_name(dev));
        return 0;
}

#endif