ARM: dma-mapping: introduce the idea of buffer ownership

The DMA API has the notion of buffer ownership; make it explicit in the
ARM implementation of this API.  This gives us a set of hooks to allow
us to deal with CPU cache issues arising from non-cache coherent DMA.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-By: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-By: Jamie Iles <jamie@jamieiles.com>

arch/arm/common/dmabounce.c

@@ -277,7 +277,7 @@ static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 		 * We don't need to sync the DMA buffer since
 		 * it was allocated via the coherent allocators.
 		 */
-		dma_cache_maint(ptr, size, dir);
+		__dma_single_cpu_to_dev(ptr, size, dir);
 	}
 
 	return dma_addr;
@@ -315,6 +315,8 @@ static inline void unmap_single(struct device *dev, dma_addr_t dma_addr,
 			__cpuc_flush_kernel_dcache_area(ptr, size);
 		}
 		free_safe_buffer(dev->archdata.dmabounce, buf);
+	} else {
+		__dma_single_dev_to_cpu(dma_to_virt(dev, dma_addr), size, dir);
 	}
 }