arch/nios2: add option to skip DMA sync as a part of map and unmap

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113518.76501.52225.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Reviewed-by: Tobias Klauser <tklauser@distanz.ch>
Cc: Ley Foon Tan <lftan@altera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/nios2/mm/dma-mapping.c b/arch/nios2/mm/dma-mapping.c
index d800fad87896307f5eb5834539734f8f2cd3afa1..f6a5dcf9d6825ff5fd0e750b9afd62a962295759 100644 (file)
--- a/arch/nios2/mm/dma-mapping.c
+++ b/arch/nios2/mm/dma-mapping.c
@@ -98,13 +98,17 @@ static int nios2_dma_map_sg(struct device *dev, struct scatterlist *sg,
        int i;
 
        for_each_sg(sg, sg, nents, i) {
-               void *addr;
+               void *addr = sg_virt(sg);
 
-               addr = sg_virt(sg);
-               if (addr) {
-                       __dma_sync_for_device(addr, sg->length, direction);
-                       sg->dma_address = sg_phys(sg);
-               }
+               if (!addr)
+                       continue;
+
+               sg->dma_address = sg_phys(sg);
+
+               if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+                       continue;
+
+               __dma_sync_for_device(addr, sg->length, direction);
        }
 
        return nents;
@@ -117,7 +121,9 @@ static dma_addr_t nios2_dma_map_page(struct device *dev, struct page *page,
 {
        void *addr = page_address(page) + offset;
 
-       __dma_sync_for_device(addr, size, direction);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               __dma_sync_for_device(addr, size, direction);
+
        return page_to_phys(page) + offset;
 }
 
@@ -125,7 +131,8 @@ static void nios2_dma_unmap_page(struct device *dev, dma_addr_t dma_address,
                size_t size, enum dma_data_direction direction,
                unsigned long attrs)
 {
-       __dma_sync_for_cpu(phys_to_virt(dma_address), size, direction);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               __dma_sync_for_cpu(phys_to_virt(dma_address), size, direction);
 }
 
 static void nios2_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
@@ -138,6 +145,9 @@ static void nios2_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
        if (direction == DMA_TO_DEVICE)
                return;
 
+       if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+               return;
+
        for_each_sg(sg, sg, nhwentries, i) {
                addr = sg_virt(sg);
                if (addr)