diff options
Diffstat (limited to 'arch/arc/mm/dma.c')
| -rw-r--r-- | arch/arc/mm/dma.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c index 71d3efff99d3..e9d93604ad0f 100644 --- a/arch/arc/mm/dma.c +++ b/arch/arc/mm/dma.c @@ -153,6 +153,19 @@ static void _dma_cache_sync(phys_addr_t paddr, size_t size, } } +/* + * arc_dma_map_page - map a portion of a page for streaming DMA + * + * Ensure that any data held in the cache is appropriately discarded + * or written back. + * + * The device owns this memory once this call has completed. The CPU + * can regain ownership by calling dma_unmap_page(). + * + * Note: while it takes struct page as arg, caller can "abuse" it to pass + * a region larger than PAGE_SIZE, provided it is physically contiguous + * and this still works correctly + */ static dma_addr_t arc_dma_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, unsigned long attrs) @@ -165,6 +178,24 @@ static dma_addr_t arc_dma_map_page(struct device *dev, struct page *page, return plat_phys_to_dma(dev, paddr); } +/* + * arc_dma_unmap_page - unmap a buffer previously mapped through dma_map_page() + * + * After this call, reads by the CPU to the buffer are guaranteed to see + * whatever the device wrote there. + * + * Note: historically this routine was not implemented for ARC + */ +static void arc_dma_unmap_page(struct device *dev, dma_addr_t handle, + size_t size, enum dma_data_direction dir, + unsigned long attrs) +{ + phys_addr_t paddr = plat_dma_to_phys(dev, handle); + + if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC)) + _dma_cache_sync(paddr, size, dir); +} + static int arc_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs) { @@ -178,6 +209,18 @@ static int arc_dma_map_sg(struct device *dev, struct scatterlist *sg, return nents; } +static void arc_dma_unmap_sg(struct device *dev, struct scatterlist *sg, + int nents, enum dma_data_direction dir, + unsigned long attrs) +{ + struct scatterlist *s; + int i; + + for_each_sg(sg, s, nents, i) + arc_dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir, + attrs); +} + static void arc_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size, enum dma_data_direction dir) { @@ -223,7 +266,9 @@ const struct dma_map_ops arc_dma_ops = { .free = arc_dma_free, .mmap = arc_dma_mmap, .map_page = arc_dma_map_page, + .unmap_page = arc_dma_unmap_page, .map_sg = arc_dma_map_sg, + .unmap_sg = arc_dma_unmap_sg, .sync_single_for_device = arc_dma_sync_single_for_device, .sync_single_for_cpu = arc_dma_sync_single_for_cpu, .sync_sg_for_cpu = arc_dma_sync_sg_for_cpu, |