When dma_buf_map struct is passed around, it's useful to be able to initialize a second map that takes care of reading/writing to an offset of the original map.
Add a helper that copies the struct and add the offset to the proper address.
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Christian König christian.koenig@amd.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Lucas De Marchi lucas.demarchi@intel.com --- include/linux/dma-buf-map.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)
diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h index 65e927d9ce33..3514a859f628 100644 --- a/include/linux/dma-buf-map.h +++ b/include/linux/dma-buf-map.h @@ -131,6 +131,35 @@ struct dma_buf_map { .is_iomem = false, \ }
+/** + * DMA_BUF_MAP_INIT_OFFSET - Initializes struct dma_buf_map from another dma_buf_map + * @map_: The dma-buf mapping structure to copy from + * @offset: Offset to add to the other mapping + * + * Initializes a new dma_buf_struct based on another. This is the equivalent of doing: + * + * .. code-block: c + * + * dma_buf_map map = other_map; + * dma_buf_map_incr(&map, &offset); + * + * Example usage: + * + * .. code-block: c + * + * void foo(struct device *dev, struct dma_buf_map *base_map) + * { + * ... + * struct dma_buf_map = DMA_BUF_MAP_INIT_OFFSET(base_map, FIELD_OFFSET); + * ... + * } + */ +#define DMA_BUF_MAP_INIT_OFFSET(map_, offset_) (struct dma_buf_map) \ + { \ + .vaddr = (map_)->vaddr + (offset_), \ + .is_iomem = (map_)->is_iomem, \ + } + /** * dma_buf_map_set_vaddr - Sets a dma-buf mapping structure to an address in system memory * @map: The dma-buf mapping structure