• Marek Szyprowski's avatar
    common: dma-mapping: introduce dma_get_sgtable() function · d2b7428e
    Marek Szyprowski authored
    This patch adds dma_get_sgtable() function which is required to let
    drivers to share the buffers allocated by DMA-mapping subsystem. Right
    now the driver gets a dma address of the allocated buffer and the kernel
    virtual mapping for it. If it wants to share it with other device (= map
    into its dma address space) it usually hacks around kernel virtual
    addresses to get pointers to pages or assumes that both devices share
    the DMA address space. Both solutions are just hacks for the special
    cases, which should be avoided in the final version of buffer sharing.
    
    To solve this issue in a generic way, a new call to DMA mapping has been
    introduced - dma_get_sgtable(). It allocates a scatter-list which
    describes the allocated buffer and lets the driver(s) to use it with
    other device(s) by calling dma_map_sg() on it.
    
    This patch provides a generic implementation based on virt_to_page()
    call. Architectures which require more sophisticated translation might
    provide their own get_sgtable() methods.
    Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
    Reviewed-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
    Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    d2b7428e
dma-mapping.h 6.97 KB