powerpc: remove unncesary swiotlb_arch_address_needs_mapping

swiotlb doesn't use swiotlb_arch_address_needs_mapping(); it uses
dma_capalbe(). We can remove unnecessary
swiotlb_arch_address_needs_mapping().

We can remove swiotlb_addr_needs_map() and is_buffer_dma_capable() in
swiotlb_pci_addr_needs_map() too; dma_capable() handles the features
that both provide.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Becky Bruce <beckyb@kernel.crashing.org>

arch/powerpc/kernel/dma-swiotlb.c

@@ -35,29 +35,12 @@ phys_addr_t swiotlb_bus_to_phys(struct device *hwdev, dma_addr_t baddr)
 	return baddr - get_dma_direct_offset(hwdev);
 }
 
-/*
- * Determine if an address needs bounce buffering via swiotlb.
- * Going forward I expect the swiotlb code to generalize on using
- * a dma_ops->addr_needs_map, and this function will move from here to the
- * generic swiotlb code.
- */
-int
-swiotlb_arch_address_needs_mapping(struct device *hwdev, dma_addr_t addr,
-				   size_t size)
-{
-	struct dma_mapping_ops *dma_ops = get_dma_ops(hwdev);
-
-	BUG_ON(!dma_ops);
-	return dma_ops->addr_needs_map(hwdev, addr, size);
-}
-
 /*
  * Determine if an address is reachable by a pci device, or if we must bounce.
  */
 static int
 swiotlb_pci_addr_needs_map(struct device *hwdev, dma_addr_t addr, size_t size)
 {
-	u64 mask = dma_get_mask(hwdev);
 	dma_addr_t max;
 	struct pci_controller *hose;
 	struct pci_dev *pdev = to_pci_dev(hwdev);
@@ -69,16 +52,9 @@ swiotlb_pci_addr_needs_map(struct device *hwdev, dma_addr_t addr, size_t size)
 	if ((addr + size > max) | (addr < hose->dma_window_base_cur))
 		return 1;
 
-	return !is_buffer_dma_capable(mask, addr, size);
-}
-
-static int
-swiotlb_addr_needs_map(struct device *hwdev, dma_addr_t addr, size_t size)
-{
-	return !is_buffer_dma_capable(dma_get_mask(hwdev), addr, size);
+	return 0;
 }
 
-
 /*
  * At the moment, all platforms that use this code only require
  * swiotlb to be used if we're operating on HIGHMEM.  Since
@@ -94,7 +70,6 @@ struct dma_mapping_ops swiotlb_dma_ops = {
 	.dma_supported = swiotlb_dma_supported,
 	.map_page = swiotlb_map_page,
 	.unmap_page = swiotlb_unmap_page,
-	.addr_needs_map = swiotlb_addr_needs_map,
 	.sync_single_range_for_cpu = swiotlb_sync_single_range_for_cpu,
 	.sync_single_range_for_device = swiotlb_sync_single_range_for_device,
 	.sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,