// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 *                   Takashi Iwai <tiwai@suse.de>
 * 
 *  Generic memory allocators
 */

#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/dma-map-ops.h>
#include <linux/genalloc.h>
#include <linux/highmem.h>
#include <linux/vmalloc.h>
#ifdef CONFIG_X86
#include <asm/set_memory.h>
#endif
#include <sound/memalloc.h>

struct snd_malloc_ops {
        void *(*alloc)(struct snd_dma_buffer *dmab, size_t size);
        void (*free)(struct snd_dma_buffer *dmab);
        dma_addr_t (*get_addr)(struct snd_dma_buffer *dmab, size_t offset);
        struct page *(*get_page)(struct snd_dma_buffer *dmab, size_t offset);
        unsigned int (*get_chunk_size)(struct snd_dma_buffer *dmab,
                                       unsigned int ofs, unsigned int size);
        int (*mmap)(struct snd_dma_buffer *dmab, struct vm_area_struct *area);
        void (*sync)(struct snd_dma_buffer *dmab, enum snd_dma_sync_mode mode);
};

#define DEFAULT_GFP \
        (GFP_KERNEL | \
         __GFP_RETRY_MAYFAIL | /* don't trigger OOM-killer */ \
         __GFP_NOWARN)   /* no stack trace print - this call is non-critical */

static const struct snd_malloc_ops *snd_dma_get_ops(struct snd_dma_buffer *dmab);

static void *__snd_dma_alloc_pages(struct snd_dma_buffer *dmab, size_t size)
{
        const struct snd_malloc_ops *ops = snd_dma_get_ops(dmab);

        if (WARN_ON_ONCE(!ops || !ops->alloc))
                return NULL;
        return ops->alloc(dmab, size);
}

/**
 * snd_dma_alloc_dir_pages - allocate the buffer area according to the given
 *      type and direction
 * @type: the DMA buffer type
 * @device: the device pointer
 * @dir: DMA direction
 * @size: the buffer size to allocate
 * @dmab: buffer allocation record to store the allocated data
 *
 * Calls the memory-allocator function for the corresponding
 * buffer type.
 *
 * Return: Zero if the buffer with the given size is allocated successfully,
 * otherwise a negative value on error.
 */
int snd_dma_alloc_dir_pages(int type, struct device *device,
                            enum dma_data_direction dir, size_t size,
                            struct snd_dma_buffer *dmab)
{
        if (WARN_ON(!size))
                return -ENXIO;
        if (WARN_ON(!dmab))
                return -ENXIO;

        size = PAGE_ALIGN(size);
        dmab->dev.type = type;
        dmab->dev.dev = device;
        dmab->dev.dir = dir;
        dmab->bytes = 0;
        dmab->addr = 0;
        dmab->private_data = NULL;
        dmab->area = __snd_dma_alloc_pages(dmab, size);
        if (!dmab->area)
                return -ENOMEM;
        dmab->bytes = size;
        return 0;
}
EXPORT_SYMBOL(snd_dma_alloc_dir_pages);

/**
 * snd_dma_alloc_pages_fallback - allocate the buffer area according to the given type with fallback
 * @type: the DMA buffer type
 * @device: the device pointer
 * @size: the buffer size to allocate
 * @dmab: buffer allocation record to store the allocated data
 *
 * Calls the memory-allocator function for the corresponding
 * buffer type.  When no space is left, this function reduces the size and
 * tries to allocate again.  The size actually allocated is stored in
 * res_size argument.
 *
 * Return: Zero if the buffer with the given size is allocated successfully,
 * otherwise a negative value on error.
 */
int snd_dma_alloc_pages_fallback(int type, struct device *device, size_t size,
                                 struct snd_dma_buffer *dmab)
{
        int err;

        while ((err = snd_dma_alloc_pages(type, device, size, dmab)) < 0) {
                if (err != -ENOMEM)
                        return err;
                if (size <= PAGE_SIZE)
                        return -ENOMEM;
                size >>= 1;
                size = PAGE_SIZE << get_order(size);
        }
        if (! dmab->area)
                return -ENOMEM;
        return 0;
}
EXPORT_SYMBOL(snd_dma_alloc_pages_fallback);

/**
 * snd_dma_free_pages - release the allocated buffer
 * @dmab: the buffer allocation record to release
 *
 * Releases the allocated buffer via snd_dma_alloc_pages().
 */
void snd_dma_free_pages(struct snd_dma_buffer *dmab)
{
        const struct snd_malloc_ops *ops = snd_dma_get_ops(dmab);

        if (ops && ops->free)
                ops->free(dmab);
}
EXPORT_SYMBOL(snd_dma_free_pages);

/* called by devres */
static void __snd_release_pages(struct device *dev, void *res)
{
        snd_dma_free_pages(res);
}

/**
 * snd_devm_alloc_dir_pages - allocate the buffer and manage with devres
 * @dev: the device pointer
 * @type: the DMA buffer type
 * @dir: DMA direction
 * @size: the buffer size to allocate
 *
 * Allocate buffer pages depending on the given type and manage using devres.
 * The pages will be released automatically at the device removal.
 *
 * Unlike snd_dma_alloc_pages(), this function requires the real device pointer,
 * hence it can't work with SNDRV_DMA_TYPE_CONTINUOUS or
 * SNDRV_DMA_TYPE_VMALLOC type.
 *
 * Return: the snd_dma_buffer object at success, or NULL if failed
 */
struct snd_dma_buffer *
snd_devm_alloc_dir_pages(struct device *dev, int type,
                         enum dma_data_direction dir, size_t size)
{
        struct snd_dma_buffer *dmab;
        int err;

        if (WARN_ON(type == SNDRV_DMA_TYPE_CONTINUOUS ||
                    type == SNDRV_DMA_TYPE_VMALLOC))
                return NULL;

        dmab = devres_alloc(__snd_release_pages, sizeof(*dmab), GFP_KERNEL);
        if (!dmab)
                return NULL;

        err = snd_dma_alloc_dir_pages(type, dev, dir, size, dmab);
        if (err < 0) {
                devres_free(dmab);
                return NULL;
        }

        devres_add(dev, dmab);
        return dmab;
}
EXPORT_SYMBOL_GPL(snd_devm_alloc_dir_pages);

/**
 * snd_dma_buffer_mmap - perform mmap of the given DMA buffer
 * @dmab: buffer allocation information
 * @area: VM area information
 *
 * Return: zero if successful, or a negative error code
 */
int snd_dma_buffer_mmap(struct snd_dma_buffer *dmab,
                        struct vm_area_struct *area)
{
        const struct snd_malloc_ops *ops;

        if (!dmab)
                return -ENOENT;
        ops = snd_dma_get_ops(dmab);
        if (ops && ops->mmap)
                return ops->mmap(dmab, area);
        else
                return -ENOENT;
}
EXPORT_SYMBOL(snd_dma_buffer_mmap);

#ifdef CONFIG_HAS_DMA
/**
 * snd_dma_buffer_sync - sync DMA buffer between CPU and device
 * @dmab: buffer allocation information
 * @mode: sync mode
 */
void snd_dma_buffer_sync(struct snd_dma_buffer *dmab,
                         enum snd_dma_sync_mode mode)
{
        const struct snd_malloc_ops *ops;

        if (!dmab || !dmab->dev.need_sync)
                return;
        ops = snd_dma_get_ops(dmab);
        if (ops && ops->sync)
                ops->sync(dmab, mode);
}
EXPORT_SYMBOL_GPL(snd_dma_buffer_sync);
#endif /* CONFIG_HAS_DMA */

/**
 * snd_sgbuf_get_addr - return the physical address at the corresponding offset
 * @dmab: buffer allocation information
 * @offset: offset in the ring buffer
 *
 * Return: the physical address
 */
dma_addr_t snd_sgbuf_get_addr(struct snd_dma_buffer *dmab, size_t offset)
{
        const struct snd_malloc_ops *ops = snd_dma_get_ops(dmab);

        if (ops && ops->get_addr)
                return ops->get_addr(dmab, offset);
        else
                return dmab->addr + offset;
}
EXPORT_SYMBOL(snd_sgbuf_get_addr);

/**
 * snd_sgbuf_get_page - return the physical page at the corresponding offset
 * @dmab: buffer allocation information
 * @offset: offset in the ring buffer
 *
 * Return: the page pointer
 */
struct page *snd_sgbuf_get_page(struct snd_dma_buffer *dmab, size_t offset)
{
        const struct snd_malloc_ops *ops = snd_dma_get_ops(dmab);

        if (ops && ops->get_page)
                return ops->get_page(dmab, offset);
        else
                return virt_to_page(dmab->area + offset);
}
EXPORT_SYMBOL(snd_sgbuf_get_page);

/**
 * snd_sgbuf_get_chunk_size - compute the max chunk size with continuous pages
 *      on sg-buffer
 * @dmab: buffer allocation information
 * @ofs: offset in the ring buffer
 * @size: the requested size
 *
 * Return: the chunk size
 */
unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,
                                      unsigned int ofs, unsigned int size)
{
        const struct snd_malloc_ops *ops = snd_dma_get_ops(dmab);

        if (ops && ops->get_chunk_size)
                return ops->get_chunk_size(dmab, ofs, size);
        else
                return size;
}
EXPORT_SYMBOL(snd_sgbuf_get_chunk_size);

/*
 * Continuous pages allocator
 */
static void *do_alloc_pages(struct device *dev, size_t size, dma_addr_t *addr,
                            bool wc)
{
        void *p;
        gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;

 again:
        p = alloc_pages_exact(size, gfp);
        if (!p)
                return NULL;
        *addr = page_to_phys(virt_to_page(p));
        if (!dev)
                return p;
        if ((*addr + size - 1) & ~dev->coherent_dma_mask) {
                if (IS_ENABLED(CONFIG_ZONE_DMA32) && !(gfp & GFP_DMA32)) {
                        gfp |= GFP_DMA32;
                        goto again;
                }
                if (IS_ENABLED(CONFIG_ZONE_DMA) && !(gfp & GFP_DMA)) {
                        gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
                        goto again;
                }
        }
#ifdef CONFIG_X86
        if (wc)
                set_memory_wc((unsigned long)(p), size >> PAGE_SHIFT);
#endif
        return p;
}

static void do_free_pages(void *p, size_t size, bool wc)
{
#ifdef CONFIG_X86
        if (wc)
                set_memory_wb((unsigned long)(p), size >> PAGE_SHIFT);
#endif
        free_pages_exact(p, size);
}


static void *snd_dma_continuous_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        return do_alloc_pages(dmab->dev.dev, size, &dmab->addr, false);
}

static void snd_dma_continuous_free(struct snd_dma_buffer *dmab)
{
        do_free_pages(dmab->area, dmab->bytes, false);
}

static int snd_dma_continuous_mmap(struct snd_dma_buffer *dmab,
                                   struct vm_area_struct *area)
{
        return remap_pfn_range(area, area->vm_start,
                               dmab->addr >> PAGE_SHIFT,
                               area->vm_end - area->vm_start,
                               area->vm_page_prot);
}

static const struct snd_malloc_ops snd_dma_continuous_ops = {
        .alloc = snd_dma_continuous_alloc,
        .free = snd_dma_continuous_free,
        .mmap = snd_dma_continuous_mmap,
};

/*
 * VMALLOC allocator
 */
static void *snd_dma_vmalloc_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        return vmalloc(size);
}

static void snd_dma_vmalloc_free(struct snd_dma_buffer *dmab)
{
        vfree(dmab->area);
}

static int snd_dma_vmalloc_mmap(struct snd_dma_buffer *dmab,
                                struct vm_area_struct *area)
{
        return remap_vmalloc_range(area, dmab->area, 0);
}

#define get_vmalloc_page_addr(dmab, offset) \
        page_to_phys(vmalloc_to_page((dmab)->area + (offset)))

static dma_addr_t snd_dma_vmalloc_get_addr(struct snd_dma_buffer *dmab,
                                           size_t offset)
{
        return get_vmalloc_page_addr(dmab, offset) + offset % PAGE_SIZE;
}

static struct page *snd_dma_vmalloc_get_page(struct snd_dma_buffer *dmab,
                                             size_t offset)
{
        return vmalloc_to_page(dmab->area + offset);
}

static unsigned int
snd_dma_vmalloc_get_chunk_size(struct snd_dma_buffer *dmab,
                               unsigned int ofs, unsigned int size)
{
        unsigned int start, end;
        unsigned long addr;

        start = ALIGN_DOWN(ofs, PAGE_SIZE);
        end = ofs + size - 1; /* the last byte address */
        /* check page continuity */
        addr = get_vmalloc_page_addr(dmab, start);
        for (;;) {
                start += PAGE_SIZE;
                if (start > end)
                        break;
                addr += PAGE_SIZE;
                if (get_vmalloc_page_addr(dmab, start) != addr)
                        return start - ofs;
        }
        /* ok, all on continuous pages */
        return size;
}

static const struct snd_malloc_ops snd_dma_vmalloc_ops = {
        .alloc = snd_dma_vmalloc_alloc,
        .free = snd_dma_vmalloc_free,
        .mmap = snd_dma_vmalloc_mmap,
        .get_addr = snd_dma_vmalloc_get_addr,
        .get_page = snd_dma_vmalloc_get_page,
        .get_chunk_size = snd_dma_vmalloc_get_chunk_size,
};

#ifdef CONFIG_HAS_DMA
/*
 * IRAM allocator
 */
#ifdef CONFIG_GENERIC_ALLOCATOR
static void *snd_dma_iram_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        struct device *dev = dmab->dev.dev;
        struct gen_pool *pool;
        void *p;

        if (dev->of_node) {
                pool = of_gen_pool_get(dev->of_node, "iram", 0);
                /* Assign the pool into private_data field */
                dmab->private_data = pool;

                p = gen_pool_dma_alloc_align(pool, size, &dmab->addr, PAGE_SIZE);
                if (p)
                        return p;
        }

        /* Internal memory might have limited size and no enough space,
         * so if we fail to malloc, try to fetch memory traditionally.
         */
        dmab->dev.type = SNDRV_DMA_TYPE_DEV;
        return __snd_dma_alloc_pages(dmab, size);
}

static void snd_dma_iram_free(struct snd_dma_buffer *dmab)
{
        struct gen_pool *pool = dmab->private_data;

        if (pool && dmab->area)
                gen_pool_free(pool, (unsigned long)dmab->area, dmab->bytes);
}

static int snd_dma_iram_mmap(struct snd_dma_buffer *dmab,
                             struct vm_area_struct *area)
{
        area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
        return remap_pfn_range(area, area->vm_start,
                               dmab->addr >> PAGE_SHIFT,
                               area->vm_end - area->vm_start,
                               area->vm_page_prot);
}

static const struct snd_malloc_ops snd_dma_iram_ops = {
        .alloc = snd_dma_iram_alloc,
        .free = snd_dma_iram_free,
        .mmap = snd_dma_iram_mmap,
};
#endif /* CONFIG_GENERIC_ALLOCATOR */

/*
 * Coherent device pages allocator
 */
static void *snd_dma_dev_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        return dma_alloc_coherent(dmab->dev.dev, size, &dmab->addr, DEFAULT_GFP);
}

static void snd_dma_dev_free(struct snd_dma_buffer *dmab)
{
        dma_free_coherent(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
}

static int snd_dma_dev_mmap(struct snd_dma_buffer *dmab,
                            struct vm_area_struct *area)
{
        return dma_mmap_coherent(dmab->dev.dev, area,
                                 dmab->area, dmab->addr, dmab->bytes);
}

static const struct snd_malloc_ops snd_dma_dev_ops = {
        .alloc = snd_dma_dev_alloc,
        .free = snd_dma_dev_free,
        .mmap = snd_dma_dev_mmap,
};

/*
 * Write-combined pages
 */
#ifdef CONFIG_SND_DMA_SGBUF
/* x86-specific allocations */
static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        void *p = do_alloc_pages(dmab->dev.dev, size, &dmab->addr, true);

        if (!p)
                return NULL;
        dmab->addr = dma_map_single(dmab->dev.dev, p, size, DMA_BIDIRECTIONAL);
        if (dma_mapping_error(dmab->dev.dev, dmab->addr)) {
                do_free_pages(dmab->area, size, true);
                return NULL;
        }
        return p;
}

static void snd_dma_wc_free(struct snd_dma_buffer *dmab)
{
        dma_unmap_single(dmab->dev.dev, dmab->addr, dmab->bytes,
                         DMA_BIDIRECTIONAL);
        do_free_pages(dmab->area, dmab->bytes, true);
}

static int snd_dma_wc_mmap(struct snd_dma_buffer *dmab,
                           struct vm_area_struct *area)
{
        area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
        return dma_mmap_coherent(dmab->dev.dev, area,
                                 dmab->area, dmab->addr, dmab->bytes);
}
#else
static void *snd_dma_wc_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        return dma_alloc_wc(dmab->dev.dev, size, &dmab->addr, DEFAULT_GFP);
}

static void snd_dma_wc_free(struct snd_dma_buffer *dmab)
{
        dma_free_wc(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
}

static int snd_dma_wc_mmap(struct snd_dma_buffer *dmab,
                           struct vm_area_struct *area)
{
        return dma_mmap_wc(dmab->dev.dev, area,
                           dmab->area, dmab->addr, dmab->bytes);
}
#endif

static const struct snd_malloc_ops snd_dma_wc_ops = {
        .alloc = snd_dma_wc_alloc,
        .free = snd_dma_wc_free,
        .mmap = snd_dma_wc_mmap,
};

/*
 * Non-contiguous pages allocator
 */
static void *snd_dma_noncontig_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        struct sg_table *sgt;
        void *p;

        sgt = dma_alloc_noncontiguous(dmab->dev.dev, size, dmab->dev.dir,
                                      DEFAULT_GFP, 0);
        if (!sgt)
                return NULL;

        dmab->dev.need_sync = dma_need_sync(dmab->dev.dev,
                                            sg_dma_address(sgt->sgl));
        p = dma_vmap_noncontiguous(dmab->dev.dev, size, sgt);
        if (p) {
                dmab->private_data = sgt;
                /* store the first page address for convenience */
                dmab->addr = snd_sgbuf_get_addr(dmab, 0);
        } else {
                dma_free_noncontiguous(dmab->dev.dev, size, sgt, dmab->dev.dir);
        }
        return p;
}

static void snd_dma_noncontig_free(struct snd_dma_buffer *dmab)
{
        dma_vunmap_noncontiguous(dmab->dev.dev, dmab->area);
        dma_free_noncontiguous(dmab->dev.dev, dmab->bytes, dmab->private_data,
                               dmab->dev.dir);
}

static int snd_dma_noncontig_mmap(struct snd_dma_buffer *dmab,
                                  struct vm_area_struct *area)
{
        return dma_mmap_noncontiguous(dmab->dev.dev, area,
                                      dmab->bytes, dmab->private_data);
}

static void snd_dma_noncontig_sync(struct snd_dma_buffer *dmab,
                                   enum snd_dma_sync_mode mode)
{
        if (mode == SNDRV_DMA_SYNC_CPU) {
                if (dmab->dev.dir == DMA_TO_DEVICE)
                        return;
                invalidate_kernel_vmap_range(dmab->area, dmab->bytes);
                dma_sync_sgtable_for_cpu(dmab->dev.dev, dmab->private_data,
                                         dmab->dev.dir);
        } else {
                if (dmab->dev.dir == DMA_FROM_DEVICE)
                        return;
                flush_kernel_vmap_range(dmab->area, dmab->bytes);
                dma_sync_sgtable_for_device(dmab->dev.dev, dmab->private_data,
                                            dmab->dev.dir);
        }
}

static inline void snd_dma_noncontig_iter_set(struct snd_dma_buffer *dmab,
                                              struct sg_page_iter *piter,
                                              size_t offset)
{
        struct sg_table *sgt = dmab->private_data;

        __sg_page_iter_start(piter, sgt->sgl, sgt->orig_nents,
                             offset >> PAGE_SHIFT);
}

static dma_addr_t snd_dma_noncontig_get_addr(struct snd_dma_buffer *dmab,
                                             size_t offset)
{
        struct sg_dma_page_iter iter;

        snd_dma_noncontig_iter_set(dmab, &iter.base, offset);
        __sg_page_iter_dma_next(&iter);
        return sg_page_iter_dma_address(&iter) + offset % PAGE_SIZE;
}

static struct page *snd_dma_noncontig_get_page(struct snd_dma_buffer *dmab,
                                               size_t offset)
{
        struct sg_page_iter iter;

        snd_dma_noncontig_iter_set(dmab, &iter, offset);
        __sg_page_iter_next(&iter);
        return sg_page_iter_page(&iter);
}

static unsigned int
snd_dma_noncontig_get_chunk_size(struct snd_dma_buffer *dmab,
                                 unsigned int ofs, unsigned int size)
{
        struct sg_dma_page_iter iter;
        unsigned int start, end;
        unsigned long addr;

        start = ALIGN_DOWN(ofs, PAGE_SIZE);
        end = ofs + size - 1; /* the last byte address */
        snd_dma_noncontig_iter_set(dmab, &iter.base, start);
        if (!__sg_page_iter_dma_next(&iter))
                return 0;
        /* check page continuity */
        addr = sg_page_iter_dma_address(&iter);
        for (;;) {
                start += PAGE_SIZE;
                if (start > end)
                        break;
                addr += PAGE_SIZE;
                if (!__sg_page_iter_dma_next(&iter) ||
                    sg_page_iter_dma_address(&iter) != addr)
                        return start - ofs;
        }
        /* ok, all on continuous pages */
        return size;
}

static const struct snd_malloc_ops snd_dma_noncontig_ops = {
        .alloc = snd_dma_noncontig_alloc,
        .free = snd_dma_noncontig_free,
        .mmap = snd_dma_noncontig_mmap,
        .sync = snd_dma_noncontig_sync,
        .get_addr = snd_dma_noncontig_get_addr,
        .get_page = snd_dma_noncontig_get_page,
        .get_chunk_size = snd_dma_noncontig_get_chunk_size,
};

#ifdef CONFIG_SND_DMA_SGBUF
/* Fallback SG-buffer allocations for x86 */
struct snd_dma_sg_fallback {
        struct sg_table sgt; /* used by get_addr - must be the first item */
        size_t count;
        struct page **pages;
        unsigned int *npages;
};

static void __snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab,
                                       struct snd_dma_sg_fallback *sgbuf)
{
        bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG;
        size_t i, size;

        if (sgbuf->pages && sgbuf->npages) {
                i = 0;
                while (i < sgbuf->count) {
                        size = sgbuf->npages[i];
                        if (!size)
                                break;
                        do_free_pages(page_address(sgbuf->pages[i]),
                                      size << PAGE_SHIFT, wc);
                        i += size;
                }
        }
        kvfree(sgbuf->pages);
        kvfree(sgbuf->npages);
        kfree(sgbuf);
}

/* fallback manual S/G buffer allocations */
static void *snd_dma_sg_fallback_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        bool wc = dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG;
        struct snd_dma_sg_fallback *sgbuf;
        struct page **pagep, *curp;
        size_t chunk;
        dma_addr_t addr;
        unsigned int idx, npages;
        void *p;

        sgbuf = kzalloc_obj(*sgbuf);
        if (!sgbuf)
                return NULL;
        size = PAGE_ALIGN(size);
        sgbuf->count = size >> PAGE_SHIFT;
        sgbuf->pages = kvzalloc_objs(*sgbuf->pages, sgbuf->count);
        sgbuf->npages = kvcalloc(sgbuf->count, sizeof(*sgbuf->npages), GFP_KERNEL);
        if (!sgbuf->pages || !sgbuf->npages)
                goto error;

        pagep = sgbuf->pages;
        chunk = size;
        idx = 0;
        while (size > 0) {
                chunk = min(size, chunk);
                p = do_alloc_pages(dmab->dev.dev, chunk, &addr, wc);
                if (!p) {
                        if (chunk <= PAGE_SIZE)
                                goto error;
                        chunk >>= 1;
                        chunk = PAGE_SIZE << get_order(chunk);
                        continue;
                }

                size -= chunk;
                /* fill pages */
                npages = chunk >> PAGE_SHIFT;
                sgbuf->npages[idx] = npages;
                idx += npages;
                curp = virt_to_page(p);
                while (npages--)
                        *pagep++ = curp++;
        }

        if (sg_alloc_table_from_pages(&sgbuf->sgt, sgbuf->pages, sgbuf->count,
                                      0, sgbuf->count << PAGE_SHIFT, GFP_KERNEL))
                goto error;

        if (dma_map_sgtable(dmab->dev.dev, &sgbuf->sgt, DMA_BIDIRECTIONAL, 0))
                goto error_dma_map;

        p = vmap(sgbuf->pages, sgbuf->count, VM_MAP, PAGE_KERNEL);
        if (!p)
                goto error_vmap;

        dmab->private_data = sgbuf;
        /* store the first page address for convenience */
        dmab->addr = snd_sgbuf_get_addr(dmab, 0);
        return p;

 error_vmap:
        dma_unmap_sgtable(dmab->dev.dev, &sgbuf->sgt, DMA_BIDIRECTIONAL, 0);
 error_dma_map:
        sg_free_table(&sgbuf->sgt);
 error:
        __snd_dma_sg_fallback_free(dmab, sgbuf);
        return NULL;
}

static void snd_dma_sg_fallback_free(struct snd_dma_buffer *dmab)
{
        struct snd_dma_sg_fallback *sgbuf = dmab->private_data;

        vunmap(dmab->area);
        dma_unmap_sgtable(dmab->dev.dev, &sgbuf->sgt, DMA_BIDIRECTIONAL, 0);
        sg_free_table(&sgbuf->sgt);
        __snd_dma_sg_fallback_free(dmab, dmab->private_data);
}

static int snd_dma_sg_fallback_mmap(struct snd_dma_buffer *dmab,
                                    struct vm_area_struct *area)
{
        struct snd_dma_sg_fallback *sgbuf = dmab->private_data;

        if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_WC_SG)
                area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
        return vm_map_pages(area, sgbuf->pages, sgbuf->count);
}

static void *snd_dma_sg_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        int type = dmab->dev.type;
        void *p;

        /* try the standard DMA API allocation at first */
        if (type == SNDRV_DMA_TYPE_DEV_WC_SG)
                dmab->dev.type = SNDRV_DMA_TYPE_DEV_WC;
        else
                dmab->dev.type = SNDRV_DMA_TYPE_DEV;
        p = __snd_dma_alloc_pages(dmab, size);
        if (p)
                return p;

        dmab->dev.type = type; /* restore the type */
        return snd_dma_sg_fallback_alloc(dmab, size);
}

static const struct snd_malloc_ops snd_dma_sg_ops = {
        .alloc = snd_dma_sg_alloc,
        .free = snd_dma_sg_fallback_free,
        .mmap = snd_dma_sg_fallback_mmap,
        /* reuse noncontig helper */
        .get_addr = snd_dma_noncontig_get_addr,
        /* reuse vmalloc helpers */
        .get_page = snd_dma_vmalloc_get_page,
        .get_chunk_size = snd_dma_vmalloc_get_chunk_size,
};
#endif /* CONFIG_SND_DMA_SGBUF */

/*
 * Non-coherent pages allocator
 */
static void *snd_dma_noncoherent_alloc(struct snd_dma_buffer *dmab, size_t size)
{
        void *p;

        p = dma_alloc_noncoherent(dmab->dev.dev, size, &dmab->addr,
                                  dmab->dev.dir, DEFAULT_GFP);
        if (p)
                dmab->dev.need_sync = dma_need_sync(dmab->dev.dev, dmab->addr);
        return p;
}

static void snd_dma_noncoherent_free(struct snd_dma_buffer *dmab)
{
        dma_free_noncoherent(dmab->dev.dev, dmab->bytes, dmab->area,
                             dmab->addr, dmab->dev.dir);
}

static int snd_dma_noncoherent_mmap(struct snd_dma_buffer *dmab,
                                    struct vm_area_struct *area)
{
        area->vm_page_prot = vm_get_page_prot(area->vm_flags);
        return dma_mmap_pages(dmab->dev.dev, area,
                              area->vm_end - area->vm_start,
                              virt_to_page(dmab->area));
}

static void snd_dma_noncoherent_sync(struct snd_dma_buffer *dmab,
                                     enum snd_dma_sync_mode mode)
{
        if (mode == SNDRV_DMA_SYNC_CPU) {
                if (dmab->dev.dir != DMA_TO_DEVICE)
                        dma_sync_single_for_cpu(dmab->dev.dev, dmab->addr,
                                                dmab->bytes, dmab->dev.dir);
        } else {
                if (dmab->dev.dir != DMA_FROM_DEVICE)
                        dma_sync_single_for_device(dmab->dev.dev, dmab->addr,
                                                   dmab->bytes, dmab->dev.dir);
        }
}

static const struct snd_malloc_ops snd_dma_noncoherent_ops = {
        .alloc = snd_dma_noncoherent_alloc,
        .free = snd_dma_noncoherent_free,
        .mmap = snd_dma_noncoherent_mmap,
        .sync = snd_dma_noncoherent_sync,
};

#endif /* CONFIG_HAS_DMA */

/*
 * Entry points
 */
static const struct snd_malloc_ops *snd_dma_ops[] = {
        [SNDRV_DMA_TYPE_CONTINUOUS] = &snd_dma_continuous_ops,
        [SNDRV_DMA_TYPE_VMALLOC] = &snd_dma_vmalloc_ops,
#ifdef CONFIG_HAS_DMA
        [SNDRV_DMA_TYPE_DEV] = &snd_dma_dev_ops,
        [SNDRV_DMA_TYPE_DEV_WC] = &snd_dma_wc_ops,
        [SNDRV_DMA_TYPE_NONCONTIG] = &snd_dma_noncontig_ops,
        [SNDRV_DMA_TYPE_NONCOHERENT] = &snd_dma_noncoherent_ops,
#ifdef CONFIG_SND_DMA_SGBUF
        [SNDRV_DMA_TYPE_DEV_SG] = &snd_dma_sg_ops,
        [SNDRV_DMA_TYPE_DEV_WC_SG] = &snd_dma_sg_ops,
#endif
#ifdef CONFIG_GENERIC_ALLOCATOR
        [SNDRV_DMA_TYPE_DEV_IRAM] = &snd_dma_iram_ops,
#endif /* CONFIG_GENERIC_ALLOCATOR */
#endif /* CONFIG_HAS_DMA */
};

static const struct snd_malloc_ops *snd_dma_get_ops(struct snd_dma_buffer *dmab)
{
        if (WARN_ON_ONCE(!dmab))
                return NULL;
        if (WARN_ON_ONCE(dmab->dev.type <= SNDRV_DMA_TYPE_UNKNOWN ||
                         dmab->dev.type >= ARRAY_SIZE(snd_dma_ops)))
                return NULL;
        return snd_dma_ops[dmab->dev.type];
}