swiotlb: allow architectures to override phys<->bus<->phys conversions

Impact: generalize phys<->bus<->phys conversions in the swiotlb code

Architectures may need to override these conversions. Implement a
__weak hook point containing the default implementation.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/swiotlb.h

@@ -27,6 +27,9 @@ swiotlb_init(void);
 extern void *swiotlb_alloc_boot(size_t bytes, unsigned long nslabs);
 extern void *swiotlb_alloc(unsigned order, unsigned long nslabs);
 
+extern dma_addr_t swiotlb_phys_to_bus(phys_addr_t address);
+extern phys_addr_t swiotlb_bus_to_phys(dma_addr_t address);
+
 extern void
 *swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 			dma_addr_t *dma_handle, gfp_t flags);

lib/swiotlb.c

@@ -125,6 +125,26 @@ void * __weak swiotlb_alloc(unsigned order, unsigned long nslabs)
 	return (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
 }
 
+dma_addr_t __weak swiotlb_phys_to_bus(phys_addr_t paddr)
+{
+	return paddr;
+}
+
+phys_addr_t __weak swiotlb_bus_to_phys(dma_addr_t baddr)
+{
+	return baddr;
+}
+
+static dma_addr_t swiotlb_virt_to_bus(volatile void *address)
+{
+	return swiotlb_phys_to_bus(virt_to_phys(address));
+}
+
+static void *swiotlb_bus_to_virt(dma_addr_t address)
+{
+	return phys_to_virt(swiotlb_bus_to_phys(address));
+}
+
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
@@ -168,7 +188,7 @@ swiotlb_init_with_default_size(size_t default_size)
 		panic("Cannot allocate SWIOTLB overflow buffer!\n");
 
 	printk(KERN_INFO "Placing software IO TLB between 0x%lx - 0x%lx\n",
-	       virt_to_bus(io_tlb_start), virt_to_bus(io_tlb_end));
+	       swiotlb_virt_to_bus(io_tlb_start), swiotlb_virt_to_bus(io_tlb_end));
 }
 
 void __init
@@ -250,7 +270,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
 
 	printk(KERN_INFO "Placing %luMB software IO TLB between 0x%lx - "
 	       "0x%lx\n", bytes >> 20,
-	       virt_to_bus(io_tlb_start), virt_to_bus(io_tlb_end));
+	       swiotlb_virt_to_bus(io_tlb_start), swiotlb_virt_to_bus(io_tlb_end));
 
 	return 0;
 
@@ -298,7 +318,7 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir)
 	unsigned long max_slots;
 
 	mask = dma_get_seg_boundary(hwdev);
-	start_dma_addr = virt_to_bus(io_tlb_start) & mask;
+	start_dma_addr = swiotlb_virt_to_bus(io_tlb_start) & mask;
 
 	offset_slots = ALIGN(start_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 
@@ -475,7 +495,7 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 		dma_mask = hwdev->coherent_dma_mask;
 
 	ret = (void *)__get_free_pages(flags, order);
-	if (ret && !is_buffer_dma_capable(dma_mask, virt_to_bus(ret), size)) {
+	if (ret && !is_buffer_dma_capable(dma_mask, swiotlb_virt_to_bus(ret), size)) {
 		/*
 		 * The allocated memory isn't reachable by the device.
 		 * Fall back on swiotlb_map_single().
@@ -496,7 +516,7 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 	}
 
 	memset(ret, 0, size);
-	dev_addr = virt_to_bus(ret);
+	dev_addr = swiotlb_virt_to_bus(ret);
 
 	/* Confirm address can be DMA'd by device */
 	if (!is_buffer_dma_capable(dma_mask, dev_addr, size)) {
@@ -556,7 +576,7 @@ dma_addr_t
 swiotlb_map_single_attrs(struct device *hwdev, void *ptr, size_t size,
 			 int dir, struct dma_attrs *attrs)
 {
-	dma_addr_t dev_addr = virt_to_bus(ptr);
+	dma_addr_t dev_addr = swiotlb_virt_to_bus(ptr);
 	void *map;
 
 	BUG_ON(dir == DMA_NONE);
@@ -577,7 +597,7 @@ swiotlb_map_single_attrs(struct device *hwdev, void *ptr, size_t size,
 		map = io_tlb_overflow_buffer;
 	}
 
-	dev_addr = virt_to_bus(map);
+	dev_addr = swiotlb_virt_to_bus(map);
 
 	/*
 	 * Ensure that the address returned is DMA'ble
@@ -607,7 +627,7 @@ void
 swiotlb_unmap_single_attrs(struct device *hwdev, dma_addr_t dev_addr,
 			   size_t size, int dir, struct dma_attrs *attrs)
 {
-	char *dma_addr = bus_to_virt(dev_addr);
+	char *dma_addr = swiotlb_bus_to_virt(dev_addr);
 
 	BUG_ON(dir == DMA_NONE);
 	if (is_swiotlb_buffer(dma_addr))
@@ -637,7 +657,7 @@ static void
 swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
 		    size_t size, int dir, int target)
 {
-	char *dma_addr = bus_to_virt(dev_addr);
+	char *dma_addr = swiotlb_bus_to_virt(dev_addr);
 
 	BUG_ON(dir == DMA_NONE);
 	if (is_swiotlb_buffer(dma_addr))
@@ -668,7 +688,7 @@ swiotlb_sync_single_range(struct device *hwdev, dma_addr_t dev_addr,
 			  unsigned long offset, size_t size,
 			  int dir, int target)
 {
-	char *dma_addr = bus_to_virt(dev_addr) + offset;
+	char *dma_addr = swiotlb_bus_to_virt(dev_addr) + offset;
 
 	BUG_ON(dir == DMA_NONE);
 	if (is_swiotlb_buffer(dma_addr))
@@ -724,7 +744,7 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
 
 	for_each_sg(sgl, sg, nelems, i) {
 		addr = SG_ENT_VIRT_ADDRESS(sg);
-		dev_addr = virt_to_bus(addr);
+		dev_addr = swiotlb_virt_to_bus(addr);
 		if (swiotlb_force ||
 		    address_needs_mapping(hwdev, dev_addr, sg->length)) {
 			void *map = map_single(hwdev, addr, sg->length, dir);
@@ -737,7 +757,7 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
 				sgl[0].dma_length = 0;
 				return 0;
 			}
-			sg->dma_address = virt_to_bus(map);
+			sg->dma_address = swiotlb_virt_to_bus(map);
 		} else
 			sg->dma_address = dev_addr;
 		sg->dma_length = sg->length;
@@ -768,7 +788,7 @@ swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 
 	for_each_sg(sgl, sg, nelems, i) {
 		if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg))
-			unmap_single(hwdev, bus_to_virt(sg->dma_address),
+			unmap_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),
 				     sg->dma_length, dir);
 		else if (dir == DMA_FROM_DEVICE)
 			dma_mark_clean(SG_ENT_VIRT_ADDRESS(sg), sg->dma_length);
@@ -801,7 +821,7 @@ swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
 
 	for_each_sg(sgl, sg, nelems, i) {
 		if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg))
-			sync_single(hwdev, bus_to_virt(sg->dma_address),
+			sync_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),
 				    sg->dma_length, dir, target);
 		else if (dir == DMA_FROM_DEVICE)
 			dma_mark_clean(SG_ENT_VIRT_ADDRESS(sg), sg->dma_length);
@@ -825,7 +845,7 @@ swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
 int
 swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
 {
-	return (dma_addr == virt_to_bus(io_tlb_overflow_buffer));
+	return (dma_addr == swiotlb_virt_to_bus(io_tlb_overflow_buffer));
 }
 
 /*
@@ -837,7 +857,7 @@ swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
 int
 swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-	return virt_to_bus(io_tlb_end - 1) <= mask;
+	return swiotlb_virt_to_bus(io_tlb_end - 1) <= mask;
 }
 
 EXPORT_SYMBOL(swiotlb_map_single);