• Marek Szyprowski's avatar
    ARM: dma-mapping: add support for IOMMU mapper · 4ce63fcd
    Marek Szyprowski authored
    
    
    This patch add a complete implementation of DMA-mapping API for
    devices which have IOMMU support.
    
    This implementation tries to optimize dma address space usage by remapping
    all possible physical memory chunks into a single dma address space chunk.
    
    DMA address space is managed on top of the bitmap stored in the
    dma_iommu_mapping structure stored in device->archdata. Platform setup
    code has to initialize parameters of the dma address space (base address,
    size, allocation precision order) with arm_iommu_create_mapping() function.
    To reduce the size of the bitmap, all allocations are aligned to the
    specified order of base 4 KiB pages.
    
    dma_alloc_* functions allocate physical memory in chunks, each with
    alloc_pages() function to avoid failing if the physical memory gets
    fragmented. In worst case the allocated buffer is composed of 4 KiB page
    chunks.
    
    dma_map_sg() function minimizes the total number of dma address space
    chunks by merging of physical memory chunks into one larger dma address
    space chunk. If requested chunk (scatter list entry) boundaries
    match physical page boundaries, most calls to dma_map_sg() requests will
    result in creating only one chunk in dma address space.
    
    dma_map_page() simply creates a mapping for the given page(s) in the dma
    address space.
    
    All dma functions also perform required cache operation like their
    counterparts from the arm linear physical memory mapping version.
    
    This patch contains code and fixes kindly provided by:
    - Krishna Reddy <vdumpa@nvidia.com>,
    - Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
    - Hiroshi DOYU <hdoyu@nvidia.com>
    Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
    Acked-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
    Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Tested-By: default avatarSubash Patel <subash.ramaswamy@linaro.org>
    4ce63fcd