// SPDX-License-Identifier: GPL-2.0
/*
 * arch-independent dma-mapping routines
 *
 * Copyright (c) 2006  SUSE Linux Products GmbH
 * Copyright (c) 2006  Tejun Heo <teheo@suse.de>
 */
#include <linux/memblock.h> /* for max_pfn */
#include <linux/acpi.h>
#include <linux/dma-map-ops.h>
#include <linux/export.h>
#include <linux/gfp.h>
#include <linux/iommu-dma.h>
#include <linux/kmsan.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include "debug.h"
#include "direct.h"

#define CREATE_TRACE_POINTS
#include <trace/events/dma.h>

#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
        defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
        defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
bool dma_default_coherent = IS_ENABLED(CONFIG_ARCH_DMA_DEFAULT_COHERENT);
#endif

/*
 * Managed DMA API
 */
struct dma_devres {
        size_t          size;
        void            *vaddr;
        dma_addr_t      dma_handle;
        unsigned long   attrs;
};

static void dmam_release(struct device *dev, void *res)
{
        struct dma_devres *this = res;

        dma_free_attrs(dev, this->size, this->vaddr, this->dma_handle,
                        this->attrs);
}

static int dmam_match(struct device *dev, void *res, void *match_data)
{
        struct dma_devres *this = res, *match = match_data;

        if (this->vaddr == match->vaddr) {
                WARN_ON(this->size != match->size ||
                        this->dma_handle != match->dma_handle);
                return 1;
        }
        return 0;
}

/**
 * dmam_free_coherent - Managed dma_free_coherent()
 * @dev: Device to free coherent memory for
 * @size: Size of allocation
 * @vaddr: Virtual address of the memory to free
 * @dma_handle: DMA handle of the memory to free
 *
 * Managed dma_free_coherent().
 */
void dmam_free_coherent(struct device *dev, size_t size, void *vaddr,
                        dma_addr_t dma_handle)
{
        struct dma_devres match_data = { size, vaddr, dma_handle };

        WARN_ON(devres_destroy(dev, dmam_release, dmam_match, &match_data));
        dma_free_coherent(dev, size, vaddr, dma_handle);
}
EXPORT_SYMBOL(dmam_free_coherent);

/**
 * dmam_alloc_attrs - Managed dma_alloc_attrs()
 * @dev: Device to allocate non_coherent memory for
 * @size: Size of allocation
 * @dma_handle: Out argument for allocated DMA handle
 * @gfp: Allocation flags
 * @attrs: Flags in the DMA_ATTR_* namespace.
 *
 * Managed dma_alloc_attrs().  Memory allocated using this function will be
 * automatically released on driver detach.
 *
 * RETURNS:
 * Pointer to allocated memory on success, NULL on failure.
 */
void *dmam_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
                gfp_t gfp, unsigned long attrs)
{
        struct dma_devres *dr;
        void *vaddr;

        dr = devres_alloc(dmam_release, sizeof(*dr), gfp);
        if (!dr)
                return NULL;

        vaddr = dma_alloc_attrs(dev, size, dma_handle, gfp, attrs);
        if (!vaddr) {
                devres_free(dr);
                return NULL;
        }

        dr->vaddr = vaddr;
        dr->dma_handle = *dma_handle;
        dr->size = size;
        dr->attrs = attrs;

        devres_add(dev, dr);

        return vaddr;
}
EXPORT_SYMBOL(dmam_alloc_attrs);

static bool dma_go_direct(struct device *dev, dma_addr_t mask,
                const struct dma_map_ops *ops)
{
        if (use_dma_iommu(dev))
                return false;

        if (likely(!ops))
                return true;

#ifdef CONFIG_DMA_OPS_BYPASS
        if (dev->dma_ops_bypass)
                return min_not_zero(mask, dev->bus_dma_limit) >=
                            dma_direct_get_required_mask(dev);
#endif
        return false;
}


/*
 * Check if the devices uses a direct mapping for streaming DMA operations.
 * This allows IOMMU drivers to set a bypass mode if the DMA mask is large
 * enough.
 */
static inline bool dma_alloc_direct(struct device *dev,
                const struct dma_map_ops *ops)
{
        return dma_go_direct(dev, dev->coherent_dma_mask, ops);
}

static inline bool dma_map_direct(struct device *dev,
                const struct dma_map_ops *ops)
{
        return dma_go_direct(dev, *dev->dma_mask, ops);
}

dma_addr_t dma_map_phys(struct device *dev, phys_addr_t phys, size_t size,
                enum dma_data_direction dir, unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        bool is_mmio = attrs & DMA_ATTR_MMIO;
        dma_addr_t addr = DMA_MAPPING_ERROR;

        BUG_ON(!valid_dma_direction(dir));

        if (WARN_ON_ONCE(!dev->dma_mask))
                return DMA_MAPPING_ERROR;

        if (!dev_is_dma_coherent(dev) && (attrs & DMA_ATTR_REQUIRE_COHERENT))
                return DMA_MAPPING_ERROR;

        if (dma_map_direct(dev, ops) ||
            (!is_mmio && arch_dma_map_phys_direct(dev, phys + size)))
                addr = dma_direct_map_phys(dev, phys, size, dir, attrs);
        else if (use_dma_iommu(dev))
                addr = iommu_dma_map_phys(dev, phys, size, dir, attrs);
        else if (ops->map_phys)
                addr = ops->map_phys(dev, phys, size, dir, attrs);

        if (!is_mmio)
                kmsan_handle_dma(phys, size, dir);
        trace_dma_map_phys(dev, phys, addr, size, dir, attrs);
        debug_dma_map_phys(dev, phys, size, dir, addr, attrs);

        return addr;
}
EXPORT_SYMBOL_GPL(dma_map_phys);

dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page,
                size_t offset, size_t size, enum dma_data_direction dir,
                unsigned long attrs)
{
        phys_addr_t phys = page_to_phys(page) + offset;

        if (unlikely(attrs & DMA_ATTR_MMIO))
                return DMA_MAPPING_ERROR;

        if (IS_ENABLED(CONFIG_DMA_API_DEBUG) &&
            WARN_ON_ONCE(is_zone_device_page(page)))
                return DMA_MAPPING_ERROR;

        return dma_map_phys(dev, phys, size, dir, attrs);
}
EXPORT_SYMBOL(dma_map_page_attrs);

void dma_unmap_phys(struct device *dev, dma_addr_t addr, size_t size,
                enum dma_data_direction dir, unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        bool is_mmio = attrs & DMA_ATTR_MMIO;

        BUG_ON(!valid_dma_direction(dir));
        if (dma_map_direct(dev, ops) ||
            (!is_mmio && arch_dma_unmap_phys_direct(dev, addr + size)))
                dma_direct_unmap_phys(dev, addr, size, dir, attrs);
        else if (use_dma_iommu(dev))
                iommu_dma_unmap_phys(dev, addr, size, dir, attrs);
        else if (ops->unmap_phys)
                ops->unmap_phys(dev, addr, size, dir, attrs);
        trace_dma_unmap_phys(dev, addr, size, dir, attrs);
        debug_dma_unmap_phys(dev, addr, size, dir);
}
EXPORT_SYMBOL_GPL(dma_unmap_phys);

void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size,
                 enum dma_data_direction dir, unsigned long attrs)
{
        if (unlikely(attrs & DMA_ATTR_MMIO))
                return;

        dma_unmap_phys(dev, addr, size, dir, attrs);
}
EXPORT_SYMBOL(dma_unmap_page_attrs);

static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
         int nents, enum dma_data_direction dir, unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        int ents;

        BUG_ON(!valid_dma_direction(dir));

        if (!dev_is_dma_coherent(dev) && (attrs & DMA_ATTR_REQUIRE_COHERENT))
                return -EOPNOTSUPP;

        if (WARN_ON_ONCE(!dev->dma_mask))
                return 0;

        if (dma_map_direct(dev, ops) ||
            arch_dma_map_sg_direct(dev, sg, nents))
                ents = dma_direct_map_sg(dev, sg, nents, dir, attrs);
        else if (use_dma_iommu(dev))
                ents = iommu_dma_map_sg(dev, sg, nents, dir, attrs);
        else
                ents = ops->map_sg(dev, sg, nents, dir, attrs);

        if (ents > 0) {
                kmsan_handle_dma_sg(sg, nents, dir);
                trace_dma_map_sg(dev, sg, nents, ents, dir, attrs);
                debug_dma_map_sg(dev, sg, nents, ents, dir, attrs);
        } else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&
                                ents != -EIO && ents != -EREMOTEIO)) {
                trace_dma_map_sg_err(dev, sg, nents, ents, dir, attrs);
                return -EIO;
        }

        return ents;
}

/**
 * dma_map_sg_attrs - Map the given buffer for DMA
 * @dev:        The device for which to perform the DMA operation
 * @sg:         The sg_table object describing the buffer
 * @nents:      Number of entries to map
 * @dir:        DMA direction
 * @attrs:      Optional DMA attributes for the map operation
 *
 * Maps a buffer described by a scatterlist passed in the sg argument with
 * nents segments for the @dir DMA operation by the @dev device.
 *
 * Returns the number of mapped entries (which can be less than nents)
 * on success. Zero is returned for any error.
 *
 * dma_unmap_sg_attrs() should be used to unmap the buffer with the
 * original sg and original nents (not the value returned by this funciton).
 */
unsigned int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
                    int nents, enum dma_data_direction dir, unsigned long attrs)
{
        int ret;

        ret = __dma_map_sg_attrs(dev, sg, nents, dir, attrs);
        if (ret < 0)
                return 0;
        return ret;
}
EXPORT_SYMBOL(dma_map_sg_attrs);

/**
 * dma_map_sgtable - Map the given buffer for DMA
 * @dev:        The device for which to perform the DMA operation
 * @sgt:        The sg_table object describing the buffer
 * @dir:        DMA direction
 * @attrs:      Optional DMA attributes for the map operation
 *
 * Maps a buffer described by a scatterlist stored in the given sg_table
 * object for the @dir DMA operation by the @dev device. After success, the
 * ownership for the buffer is transferred to the DMA domain.  One has to
 * call dma_sync_sgtable_for_cpu() or dma_unmap_sgtable() to move the
 * ownership of the buffer back to the CPU domain before touching the
 * buffer by the CPU.
 *
 * Returns 0 on success or a negative error code on error. The following
 * error codes are supported with the given meaning:
 *
 *   -EINVAL            An invalid argument, unaligned access or other error
 *                      in usage. Will not succeed if retried.
 *   -ENOMEM            Insufficient resources (like memory or IOVA space) to
 *                      complete the mapping. Should succeed if retried later.
 *   -EIO               Legacy error code with an unknown meaning. eg. this is
 *                      returned if a lower level call returned
 *                      DMA_MAPPING_ERROR.
 *   -EREMOTEIO         The DMA device cannot access P2PDMA memory specified
 *                      in the sg_table. This will not succeed if retried.
 */
int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
                    enum dma_data_direction dir, unsigned long attrs)
{
        int nents;

        nents = __dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs);
        if (nents < 0)
                return nents;
        sgt->nents = nents;
        return 0;
}
EXPORT_SYMBOL_GPL(dma_map_sgtable);

void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
                                      int nents, enum dma_data_direction dir,
                                      unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        BUG_ON(!valid_dma_direction(dir));
        trace_dma_unmap_sg(dev, sg, nents, dir, attrs);
        debug_dma_unmap_sg(dev, sg, nents, dir);
        if (dma_map_direct(dev, ops) ||
            arch_dma_unmap_sg_direct(dev, sg, nents))
                dma_direct_unmap_sg(dev, sg, nents, dir, attrs);
        else if (use_dma_iommu(dev))
                iommu_dma_unmap_sg(dev, sg, nents, dir, attrs);
        else if (ops->unmap_sg)
                ops->unmap_sg(dev, sg, nents, dir, attrs);
}
EXPORT_SYMBOL(dma_unmap_sg_attrs);

dma_addr_t dma_map_resource(struct device *dev, phys_addr_t phys_addr,
                size_t size, enum dma_data_direction dir, unsigned long attrs)
{
        if (IS_ENABLED(CONFIG_DMA_API_DEBUG) &&
            WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr))))
                return DMA_MAPPING_ERROR;

        return dma_map_phys(dev, phys_addr, size, dir, attrs | DMA_ATTR_MMIO);
}
EXPORT_SYMBOL(dma_map_resource);

void dma_unmap_resource(struct device *dev, dma_addr_t addr, size_t size,
                enum dma_data_direction dir, unsigned long attrs)
{
        dma_unmap_phys(dev, addr, size, dir, attrs | DMA_ATTR_MMIO);
}
EXPORT_SYMBOL(dma_unmap_resource);

#ifdef CONFIG_DMA_NEED_SYNC
void __dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size,
                enum dma_data_direction dir)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        BUG_ON(!valid_dma_direction(dir));
        if (dma_map_direct(dev, ops))
                dma_direct_sync_single_for_cpu(dev, addr, size, dir);
        else if (use_dma_iommu(dev))
                iommu_dma_sync_single_for_cpu(dev, addr, size, dir);
        else if (ops->sync_single_for_cpu)
                ops->sync_single_for_cpu(dev, addr, size, dir);
        trace_dma_sync_single_for_cpu(dev, addr, size, dir);
        debug_dma_sync_single_for_cpu(dev, addr, size, dir);
}
EXPORT_SYMBOL(__dma_sync_single_for_cpu);

void __dma_sync_single_for_device(struct device *dev, dma_addr_t addr,
                size_t size, enum dma_data_direction dir)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        BUG_ON(!valid_dma_direction(dir));
        if (dma_map_direct(dev, ops))
                dma_direct_sync_single_for_device(dev, addr, size, dir);
        else if (use_dma_iommu(dev))
                iommu_dma_sync_single_for_device(dev, addr, size, dir);
        else if (ops->sync_single_for_device)
                ops->sync_single_for_device(dev, addr, size, dir);
        trace_dma_sync_single_for_device(dev, addr, size, dir);
        debug_dma_sync_single_for_device(dev, addr, size, dir);
}
EXPORT_SYMBOL(__dma_sync_single_for_device);

void __dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
                    int nelems, enum dma_data_direction dir)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        BUG_ON(!valid_dma_direction(dir));
        if (dma_map_direct(dev, ops))
                dma_direct_sync_sg_for_cpu(dev, sg, nelems, dir);
        else if (use_dma_iommu(dev))
                iommu_dma_sync_sg_for_cpu(dev, sg, nelems, dir);
        else if (ops->sync_sg_for_cpu)
                ops->sync_sg_for_cpu(dev, sg, nelems, dir);
        trace_dma_sync_sg_for_cpu(dev, sg, nelems, dir);
        debug_dma_sync_sg_for_cpu(dev, sg, nelems, dir);
}
EXPORT_SYMBOL(__dma_sync_sg_for_cpu);

void __dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
                       int nelems, enum dma_data_direction dir)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        BUG_ON(!valid_dma_direction(dir));
        if (dma_map_direct(dev, ops))
                dma_direct_sync_sg_for_device(dev, sg, nelems, dir);
        else if (use_dma_iommu(dev))
                iommu_dma_sync_sg_for_device(dev, sg, nelems, dir);
        else if (ops->sync_sg_for_device)
                ops->sync_sg_for_device(dev, sg, nelems, dir);
        trace_dma_sync_sg_for_device(dev, sg, nelems, dir);
        debug_dma_sync_sg_for_device(dev, sg, nelems, dir);
}
EXPORT_SYMBOL(__dma_sync_sg_for_device);

bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_map_direct(dev, ops))
                /*
                 * dma_skip_sync could've been reset on first SWIOTLB buffer
                 * mapping, but @dma_addr is not necessary an SWIOTLB buffer.
                 * In this case, fall back to more granular check.
                 */
                return dma_direct_need_sync(dev, dma_addr);
        return true;
}
EXPORT_SYMBOL_GPL(__dma_need_sync);

/**
 * dma_need_unmap - does this device need dma_unmap_* operations
 * @dev: device to check
 *
 * If this function returns %false, drivers can skip calling dma_unmap_* after
 * finishing an I/O.  This function must be called after all mappings that might
 * need to be unmapped have been performed.
 */
bool dma_need_unmap(struct device *dev)
{
        if (!dma_map_direct(dev, get_dma_ops(dev)))
                return true;
        if (!dev->dma_skip_sync)
                return true;
        return IS_ENABLED(CONFIG_DMA_API_DEBUG);
}
EXPORT_SYMBOL_GPL(dma_need_unmap);

static void dma_setup_need_sync(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_map_direct(dev, ops) || use_dma_iommu(dev))
                /*
                 * dma_skip_sync will be reset to %false on first SWIOTLB buffer
                 * mapping, if any. During the device initialization, it's
                 * enough to check only for the DMA coherence.
                 */
                dev->dma_skip_sync = dev_is_dma_coherent(dev);
        else if (!ops->sync_single_for_device && !ops->sync_single_for_cpu &&
                 !ops->sync_sg_for_device && !ops->sync_sg_for_cpu)
                /*
                 * Synchronization is not possible when none of DMA sync ops
                 * is set.
                 */
                dev->dma_skip_sync = true;
        else
                dev->dma_skip_sync = false;
}
#else /* !CONFIG_DMA_NEED_SYNC */
static inline void dma_setup_need_sync(struct device *dev) { }
#endif /* !CONFIG_DMA_NEED_SYNC */

/*
 * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems
 * that the intention is to allow exporting memory allocated via the
 * coherent DMA APIs through the dma_buf API, which only accepts a
 * scattertable.  This presents a couple of problems:
 * 1. Not all memory allocated via the coherent DMA APIs is backed by
 *    a struct page
 * 2. Passing coherent DMA memory into the streaming APIs is not allowed
 *    as we will try to flush the memory through a different alias to that
 *    actually being used (and the flushes are redundant.)
 */
int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
                void *cpu_addr, dma_addr_t dma_addr, size_t size,
                unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_alloc_direct(dev, ops))
                return dma_direct_get_sgtable(dev, sgt, cpu_addr, dma_addr,
                                size, attrs);
        if (use_dma_iommu(dev))
                return iommu_dma_get_sgtable(dev, sgt, cpu_addr, dma_addr,
                                size, attrs);
        if (!ops->get_sgtable)
                return -ENXIO;
        return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size, attrs);
}
EXPORT_SYMBOL(dma_get_sgtable_attrs);

#ifdef CONFIG_MMU
/*
 * Return the page attributes used for mapping dma_alloc_* memory, either in
 * kernel space if remapping is needed, or to userspace through dma_mmap_*.
 */
pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
{
        if (dev_is_dma_coherent(dev))
                return prot;
#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE
        if (attrs & DMA_ATTR_WRITE_COMBINE)
                return pgprot_writecombine(prot);
#endif
        return pgprot_dmacoherent(prot);
}
#endif /* CONFIG_MMU */

/**
 * dma_can_mmap - check if a given device supports dma_mmap_*
 * @dev: device to check
 *
 * Returns %true if @dev supports dma_mmap_coherent() and dma_mmap_attrs() to
 * map DMA allocations to userspace.
 */
bool dma_can_mmap(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_alloc_direct(dev, ops))
                return dma_direct_can_mmap(dev);
        if (use_dma_iommu(dev))
                return true;
        return ops->mmap != NULL;
}
EXPORT_SYMBOL_GPL(dma_can_mmap);

/**
 * dma_mmap_attrs - map a coherent DMA allocation into user space
 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 * @vma: vm_area_struct describing requested user mapping
 * @cpu_addr: kernel CPU-view address returned from dma_alloc_attrs
 * @dma_addr: device-view address returned from dma_alloc_attrs
 * @size: size of memory originally requested in dma_alloc_attrs
 * @attrs: attributes of mapping properties requested in dma_alloc_attrs
 *
 * Map a coherent DMA buffer previously allocated by dma_alloc_attrs into user
 * space.  The coherent DMA buffer must not be freed by the driver until the
 * user space mapping has been released.
 */
int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
                void *cpu_addr, dma_addr_t dma_addr, size_t size,
                unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_alloc_direct(dev, ops))
                return dma_direct_mmap(dev, vma, cpu_addr, dma_addr, size,
                                attrs);
        if (use_dma_iommu(dev))
                return iommu_dma_mmap(dev, vma, cpu_addr, dma_addr, size,
                                      attrs);
        if (!ops->mmap)
                return -ENXIO;
        return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
}
EXPORT_SYMBOL(dma_mmap_attrs);

u64 dma_get_required_mask(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_alloc_direct(dev, ops))
                return dma_direct_get_required_mask(dev);

        if (use_dma_iommu(dev))
                return DMA_BIT_MASK(32);

        if (ops->get_required_mask)
                return ops->get_required_mask(dev);

        /*
         * We require every DMA ops implementation to at least support a 32-bit
         * DMA mask (and use bounce buffering if that isn't supported in
         * hardware).  As the direct mapping code has its own routine to
         * actually report an optimal mask we default to 32-bit here as that
         * is the right thing for most IOMMUs, and at least not actively
         * harmful in general.
         */
        return DMA_BIT_MASK(32);
}
EXPORT_SYMBOL_GPL(dma_get_required_mask);

void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
                gfp_t flag, unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        void *cpu_addr;

        WARN_ON_ONCE(!dev->coherent_dma_mask);

        /*
         * DMA allocations can never be turned back into a page pointer, so
         * requesting compound pages doesn't make sense (and can't even be
         * supported at all by various backends).
         */
        if (WARN_ON_ONCE(flag & __GFP_COMP))
                return NULL;

        if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr)) {
                trace_dma_alloc(dev, cpu_addr, *dma_handle, size,
                                DMA_BIDIRECTIONAL, flag, attrs);
                return cpu_addr;
        }

        /* let the implementation decide on the zone to allocate from: */
        flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);

        if (dma_alloc_direct(dev, ops) || arch_dma_alloc_direct(dev)) {
                cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, attrs);
        } else if (use_dma_iommu(dev)) {
                cpu_addr = iommu_dma_alloc(dev, size, dma_handle, flag, attrs);
        } else if (ops->alloc) {
                cpu_addr = ops->alloc(dev, size, dma_handle, flag, attrs);
        } else {
                trace_dma_alloc(dev, NULL, 0, size, DMA_BIDIRECTIONAL, flag,
                                attrs);
                return NULL;
        }

        trace_dma_alloc(dev, cpu_addr, *dma_handle, size, DMA_BIDIRECTIONAL,
                        flag, attrs);
        debug_dma_alloc_coherent(dev, size, *dma_handle, cpu_addr, attrs);
        return cpu_addr;
}
EXPORT_SYMBOL(dma_alloc_attrs);

void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
                dma_addr_t dma_handle, unsigned long attrs)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (dma_release_from_dev_coherent(dev, get_order(size), cpu_addr))
                return;
        /*
         * On non-coherent platforms which implement DMA-coherent buffers via
         * non-cacheable remaps, ops->free() may call vunmap(). Thus getting
         * this far in IRQ context is a) at risk of a BUG_ON() or trying to
         * sleep on some machines, and b) an indication that the driver is
         * probably misusing the coherent API anyway.
         */
        WARN_ON(irqs_disabled());

        trace_dma_free(dev, cpu_addr, dma_handle, size, DMA_BIDIRECTIONAL,
                       attrs);
        if (!cpu_addr)
                return;

        debug_dma_free_coherent(dev, size, cpu_addr, dma_handle);
        if (dma_alloc_direct(dev, ops) || arch_dma_free_direct(dev, dma_handle))
                dma_direct_free(dev, size, cpu_addr, dma_handle, attrs);
        else if (use_dma_iommu(dev))
                iommu_dma_free(dev, size, cpu_addr, dma_handle, attrs);
        else if (ops->free)
                ops->free(dev, size, cpu_addr, dma_handle, attrs);
}
EXPORT_SYMBOL(dma_free_attrs);

static struct page *__dma_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (WARN_ON_ONCE(!dev->coherent_dma_mask))
                return NULL;
        if (WARN_ON_ONCE(gfp & (__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM)))
                return NULL;
        if (WARN_ON_ONCE(gfp & __GFP_COMP))
                return NULL;

        size = PAGE_ALIGN(size);
        if (dma_alloc_direct(dev, ops))
                return dma_direct_alloc_pages(dev, size, dma_handle, dir, gfp);
        if (use_dma_iommu(dev))
                return dma_common_alloc_pages(dev, size, dma_handle, dir, gfp);
        if (!ops->alloc_pages_op)
                return NULL;
        return ops->alloc_pages_op(dev, size, dma_handle, dir, gfp);
}

struct page *dma_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
{
        struct page *page = __dma_alloc_pages(dev, size, dma_handle, dir, gfp);

        if (page) {
                trace_dma_alloc_pages(dev, page_to_virt(page), *dma_handle,
                                      size, dir, gfp, 0);
                debug_dma_alloc_pages(dev, page, size, dir, *dma_handle, 0);
        } else {
                trace_dma_alloc_pages(dev, NULL, 0, size, dir, gfp, 0);
        }
        return page;
}
EXPORT_SYMBOL_GPL(dma_alloc_pages);

static void __dma_free_pages(struct device *dev, size_t size, struct page *page,
                dma_addr_t dma_handle, enum dma_data_direction dir)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        size = PAGE_ALIGN(size);
        if (dma_alloc_direct(dev, ops))
                dma_direct_free_pages(dev, size, page, dma_handle, dir);
        else if (use_dma_iommu(dev))
                dma_common_free_pages(dev, size, page, dma_handle, dir);
        else if (ops->free_pages)
                ops->free_pages(dev, size, page, dma_handle, dir);
}

void dma_free_pages(struct device *dev, size_t size, struct page *page,
                dma_addr_t dma_handle, enum dma_data_direction dir)
{
        trace_dma_free_pages(dev, page_to_virt(page), dma_handle, size, dir, 0);
        debug_dma_free_pages(dev, page, size, dir, dma_handle);
        __dma_free_pages(dev, size, page, dma_handle, dir);
}
EXPORT_SYMBOL_GPL(dma_free_pages);

int dma_mmap_pages(struct device *dev, struct vm_area_struct *vma,
                size_t size, struct page *page)
{
        unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;

        if (vma->vm_pgoff >= count || vma_pages(vma) > count - vma->vm_pgoff)
                return -ENXIO;
        return remap_pfn_range(vma, vma->vm_start,
                               page_to_pfn(page) + vma->vm_pgoff,
                               vma_pages(vma) << PAGE_SHIFT, vma->vm_page_prot);
}
EXPORT_SYMBOL_GPL(dma_mmap_pages);

static struct sg_table *alloc_single_sgt(struct device *dev, size_t size,
                enum dma_data_direction dir, gfp_t gfp)
{
        struct sg_table *sgt;
        struct page *page;

        sgt = kmalloc_obj(*sgt, gfp);
        if (!sgt)
                return NULL;
        if (sg_alloc_table(sgt, 1, gfp))
                goto out_free_sgt;
        page = __dma_alloc_pages(dev, size, &sgt->sgl->dma_address, dir, gfp);
        if (!page)
                goto out_free_table;
        sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
        sg_dma_len(sgt->sgl) = sgt->sgl->length;
        return sgt;
out_free_table:
        sg_free_table(sgt);
out_free_sgt:
        kfree(sgt);
        return NULL;
}

struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
                enum dma_data_direction dir, gfp_t gfp, unsigned long attrs)
{
        struct sg_table *sgt;

        if (WARN_ON_ONCE(attrs & ~DMA_ATTR_ALLOC_SINGLE_PAGES))
                return NULL;
        if (WARN_ON_ONCE(gfp & __GFP_COMP))
                return NULL;

        if (use_dma_iommu(dev))
                sgt = iommu_dma_alloc_noncontiguous(dev, size, dir, gfp, attrs);
        else
                sgt = alloc_single_sgt(dev, size, dir, gfp);

        if (sgt) {
                sgt->nents = 1;
                trace_dma_alloc_sgt(dev, sgt, size, dir, gfp, attrs);
                debug_dma_map_sg(dev, sgt->sgl, sgt->orig_nents, 1, dir, attrs);
        } else {
                trace_dma_alloc_sgt_err(dev, NULL, 0, size, dir, gfp, attrs);
        }
        return sgt;
}
EXPORT_SYMBOL_GPL(dma_alloc_noncontiguous);

static void free_single_sgt(struct device *dev, size_t size,
                struct sg_table *sgt, enum dma_data_direction dir)
{
        __dma_free_pages(dev, size, sg_page(sgt->sgl), sgt->sgl->dma_address,
                         dir);
        sg_free_table(sgt);
        kfree(sgt);
}

void dma_free_noncontiguous(struct device *dev, size_t size,
                struct sg_table *sgt, enum dma_data_direction dir)
{
        trace_dma_free_sgt(dev, sgt, size, dir);
        debug_dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);

        if (use_dma_iommu(dev))
                iommu_dma_free_noncontiguous(dev, size, sgt, dir);
        else
                free_single_sgt(dev, size, sgt, dir);
}
EXPORT_SYMBOL_GPL(dma_free_noncontiguous);

void *dma_vmap_noncontiguous(struct device *dev, size_t size,
                struct sg_table *sgt)
{

        if (use_dma_iommu(dev))
                return iommu_dma_vmap_noncontiguous(dev, size, sgt);

        return page_address(sg_page(sgt->sgl));
}
EXPORT_SYMBOL_GPL(dma_vmap_noncontiguous);

void dma_vunmap_noncontiguous(struct device *dev, void *vaddr)
{
        if (use_dma_iommu(dev))
                iommu_dma_vunmap_noncontiguous(dev, vaddr);
}
EXPORT_SYMBOL_GPL(dma_vunmap_noncontiguous);

int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
                size_t size, struct sg_table *sgt)
{
        if (use_dma_iommu(dev))
                return iommu_dma_mmap_noncontiguous(dev, vma, size, sgt);
        return dma_mmap_pages(dev, vma, size, sg_page(sgt->sgl));
}
EXPORT_SYMBOL_GPL(dma_mmap_noncontiguous);

static int dma_supported(struct device *dev, u64 mask)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (use_dma_iommu(dev)) {
                if (WARN_ON(ops))
                        return false;
                return true;
        }

        /*
         * ->dma_supported sets and clears the bypass flag, so ignore it here
         * and always call into the method if there is one.
         */
        if (ops) {
                if (!ops->dma_supported)
                        return true;
                return ops->dma_supported(dev, mask);
        }

        return dma_direct_supported(dev, mask);
}

bool dma_pci_p2pdma_supported(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        /*
         * Note: dma_ops_bypass is not checked here because P2PDMA should
         * not be used with dma mapping ops that do not have support even
         * if the specific device is bypassing them.
         */

        /* if ops is not set, dma direct and default IOMMU support P2PDMA */
        return !ops;
}
EXPORT_SYMBOL_GPL(dma_pci_p2pdma_supported);

int dma_set_mask(struct device *dev, u64 mask)
{
        /*
         * Truncate the mask to the actually supported dma_addr_t width to
         * avoid generating unsupportable addresses.
         */
        mask = (dma_addr_t)mask;

        if (!dev->dma_mask || !dma_supported(dev, mask))
                return -EIO;

        arch_dma_set_mask(dev, mask);
        *dev->dma_mask = mask;
        dma_setup_need_sync(dev);

        return 0;
}
EXPORT_SYMBOL(dma_set_mask);

int dma_set_coherent_mask(struct device *dev, u64 mask)
{
        /*
         * Truncate the mask to the actually supported dma_addr_t width to
         * avoid generating unsupportable addresses.
         */
        mask = (dma_addr_t)mask;

        if (!dma_supported(dev, mask))
                return -EIO;

        dev->coherent_dma_mask = mask;
        return 0;
}
EXPORT_SYMBOL(dma_set_coherent_mask);

static bool __dma_addressing_limited(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (min_not_zero(dma_get_mask(dev), dev->bus_dma_limit) <
                         dma_get_required_mask(dev))
                return true;

        if (unlikely(ops) || use_dma_iommu(dev))
                return false;
        return !dma_direct_all_ram_mapped(dev);
}

/**
 * dma_addressing_limited - return if the device is addressing limited
 * @dev:        device to check
 *
 * Return %true if the devices DMA mask is too small to address all memory in
 * the system, else %false.  Lack of addressing bits is the prime reason for
 * bounce buffering, but might not be the only one.
 */
bool dma_addressing_limited(struct device *dev)
{
        if (!__dma_addressing_limited(dev))
                return false;

        dev_dbg(dev, "device is DMA addressing limited\n");
        return true;
}
EXPORT_SYMBOL_GPL(dma_addressing_limited);

size_t dma_max_mapping_size(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        size_t size = SIZE_MAX;

        if (dma_map_direct(dev, ops))
                size = dma_direct_max_mapping_size(dev);
        else if (use_dma_iommu(dev))
                size = iommu_dma_max_mapping_size(dev);
        else if (ops && ops->max_mapping_size)
                size = ops->max_mapping_size(dev);

        return size;
}
EXPORT_SYMBOL_GPL(dma_max_mapping_size);

size_t dma_opt_mapping_size(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);
        size_t size = SIZE_MAX;

        if (use_dma_iommu(dev))
                size = iommu_dma_opt_mapping_size();
        else if (ops && ops->opt_mapping_size)
                size = ops->opt_mapping_size();

        return min(dma_max_mapping_size(dev), size);
}
EXPORT_SYMBOL_GPL(dma_opt_mapping_size);

unsigned long dma_get_merge_boundary(struct device *dev)
{
        const struct dma_map_ops *ops = get_dma_ops(dev);

        if (use_dma_iommu(dev))
                return iommu_dma_get_merge_boundary(dev);

        if (!ops || !ops->get_merge_boundary)
                return 0;       /* can't merge */

        return ops->get_merge_boundary(dev);
}
EXPORT_SYMBOL_GPL(dma_get_merge_boundary);