x86: move dma_unmap_sg to common header

i386 gets an empty function.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/pci-base_32.c

@@ -34,6 +34,7 @@ static const struct dma_mapping_ops pci32_dma_ops = {
 	.map_single = pci32_map_single,
 	.unmap_single = NULL,
 	.map_sg = pci32_dma_map_sg,
+	.unmap_sg = NULL,
 };
 
 const struct dma_mapping_ops *dma_ops = &pci32_dma_ops;

include/asm-x86/dma-mapping.h

@@ -82,4 +82,13 @@ dma_map_sg(struct device *hwdev, struct scatterlist *sg,
 	BUG_ON(!valid_dma_direction(direction));
 	return dma_ops->map_sg(hwdev, sg, nents, direction);
 }
+
+static inline void
+dma_unmap_sg(struct device *hwdev, struct scatterlist *sg, int nents,
+	     int direction)
+{
+	BUG_ON(!valid_dma_direction(direction));
+	if (dma_ops->unmap_sg)
+		dma_ops->unmap_sg(hwdev, sg, nents, direction);
+}
 #endif

include/asm-x86/dma-mapping_32.h

@@ -32,14 +32,6 @@ dma_unmap_page(struct device *dev, dma_addr_t dma_address, size_t size,
 	BUG_ON(!valid_dma_direction(direction));
 }
 
-
-static inline void
-dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nhwentries,
-	     enum dma_data_direction direction)
-{
-	BUG_ON(!valid_dma_direction(direction));
-}
-
 static inline void
 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
 			enum dma_data_direction direction)

include/asm-x86/dma-mapping_64.h

@@ -96,14 +96,6 @@ dma_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
 	flush_write_buffers();
 }
 
-static inline void
-dma_unmap_sg(struct device *hwdev, struct scatterlist *sg, int nents,
-	     int direction)
-{
-	BUG_ON(!valid_dma_direction(direction));
-	dma_ops->unmap_sg(hwdev, sg, nents, direction);
-}
-
 extern int dma_supported(struct device *hwdev, u64 mask);
 
 /* same for gart, swiotlb, and nommu */