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    Subject[PATCH 27/34] dma-direct: add support for CMA allocation
    Date
    Try the CMA allocator for coherent allocations if supported.

    Roughly modelled after the x86 code.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    ---
    lib/dma-direct.c | 24 ++++++++++++++++++------
    1 file changed, 18 insertions(+), 6 deletions(-)

    diff --git a/lib/dma-direct.c b/lib/dma-direct.c
    index 32fd4d9e4c47..a9ae98be7af3 100644
    --- a/lib/dma-direct.c
    +++ b/lib/dma-direct.c
    @@ -7,6 +7,7 @@
    #include <linux/mm.h>
    #include <linux/dma-direct.h>
    #include <linux/scatterlist.h>
    +#include <linux/dma-contiguous.h>
    #include <linux/pfn.h>

    #define DIRECT_MAPPING_ERROR 0
    @@ -29,19 +30,30 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
    static void *dma_direct_alloc(struct device *dev, size_t size,
    dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
    {
    - void *ret;
    + unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
    + int page_order = get_order(size);
    + struct page *page = NULL;

    - ret = (void *)__get_free_pages(gfp, get_order(size));
    - if (ret)
    - *dma_handle = phys_to_dma(dev, virt_to_phys(ret));
    + /* CMA can be used only in the context which permits sleeping */
    + if (gfpflags_allow_blocking(gfp))
    + page = dma_alloc_from_contiguous(dev, count, page_order, gfp);
    + if (!page)
    + page = alloc_pages(gfp, page_order);
    + if (!page)
    + return NULL;

    - return ret;
    + *dma_handle = phys_to_dma(dev, page_to_phys(page));
    + memset(page_address(page), 0, size);
    + return page_address(page);
    }

    static void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
    dma_addr_t dma_addr, unsigned long attrs)
    {
    - free_pages((unsigned long)cpu_addr, get_order(size));
    + unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
    +
    + if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
    + free_pages((unsigned long)cpu_addr, get_order(size));
    }

    static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
    --
    2.14.2
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