x86, swiotlb: add map_page and unmap_page

This is a preparation of struct dma_mapping_ops unification. We use
map_page and unmap_page instead of map_single and unmap_single.

This is sorta temporary workaround. We will move them to lib/swiotlb.c
to enable x86's swiotlb code to directly use them.

We will remove map_single and unmap_single hooks in the last patch in
this patchset.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/pci-swiotlb_64.c

@@ -45,6 +45,23 @@ swiotlb_map_single_phys(struct device *hwdev, phys_addr_t paddr, size_t size,
 	return swiotlb_map_single(hwdev, phys_to_virt(paddr), size, direction);
 }
 
+/* these will be moved to lib/swiotlb.c later on */
+
+static dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
+				   unsigned long offset, size_t size,
+				   enum dma_data_direction dir,
+				   struct dma_attrs *attrs)
+{
+	return swiotlb_map_single(dev, page_address(page) + offset, size, dir);
+}
+
+static void swiotlb_unmap_page(struct device *dev, dma_addr_t dma_handle,
+			       size_t size, enum dma_data_direction dir,
+			       struct dma_attrs *attrs)
+{
+	swiotlb_unmap_single(dev, dma_handle, size, dir);
+}
+
 static void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 					dma_addr_t *dma_handle, gfp_t flags)
 {
@@ -71,6 +88,8 @@ struct dma_mapping_ops swiotlb_dma_ops = {
 	.sync_sg_for_device = swiotlb_sync_sg_for_device,
 	.map_sg = swiotlb_map_sg,
 	.unmap_sg = swiotlb_unmap_sg,
+	.map_page = swiotlb_map_page,
+	.unmap_page = swiotlb_unmap_page,
 	.dma_supported = NULL,
 };