arch/avr32: add option to skip sync on DMA map

The use of DMA_ATTR_SKIP_CPU_SYNC was not consistent across all of the
DMA APIs in the arch/arm folder.  This change is meant to correct that
so that we get consistent behavior.

Link: http://lkml.kernel.org/r/20161110113430.76501.79737.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/avr32/mm/dma-coherent.c

@@ -146,7 +146,8 @@ static dma_addr_t avr32_dma_map_page(struct device *dev, struct page *page,
 {
 	void *cpu_addr = page_address(page) + offset;
 
-	dma_cache_sync(dev, cpu_addr, size, direction);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		dma_cache_sync(dev, cpu_addr, size, direction);
 	return virt_to_bus(cpu_addr);
 }
 
@@ -162,6 +163,10 @@ static int avr32_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 
 		sg->dma_address = page_to_bus(sg_page(sg)) + sg->offset;
 		virt = sg_virt(sg);
+
+		if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+			continue;
+
 		dma_cache_sync(dev, virt, sg->length, direction);
 	}