swiotlb: add a IO_TLB_SIZE define

Add a new IO_TLB_SIZE define instead open coding it using
IO_TLB_SHIFT all over.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jianxiong Gao <jxgao@google.com>
Tested-by: Jianxiong Gao <jxgao@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

include/linux/swiotlb.h

@@ -29,6 +29,7 @@ enum swiotlb_force {
  * controllable.
  */
 #define IO_TLB_SHIFT 11
+#define IO_TLB_SIZE (1 << IO_TLB_SHIFT)
 
 /* default to 64MB */
 #define IO_TLB_DEFAULT_SIZE (64UL<<20)

kernel/dma/swiotlb.c

@@ -171,7 +171,7 @@ void __init swiotlb_adjust_size(unsigned long new_size)
 	 * adjust/expand SWIOTLB size for their use.
 	 */
 	if (!io_tlb_nslabs) {
-		size = ALIGN(new_size, 1 << IO_TLB_SHIFT);
+		size = ALIGN(new_size, IO_TLB_SIZE);
 		io_tlb_nslabs = size >> IO_TLB_SHIFT;
 		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 
@@ -491,20 +491,20 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 
 	tbl_dma_addr &= mask;
 
-	offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	offset_slots = ALIGN(tbl_dma_addr, IO_TLB_SIZE) >> IO_TLB_SHIFT;
 
 	/*
 	 * Carefully handle integer overflow which can occur when mask == ~0UL.
 	 */
 	max_slots = mask + 1
-		    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
+		    ? ALIGN(mask + 1, IO_TLB_SIZE) >> IO_TLB_SHIFT
 		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 
 	/*
 	 * For mappings greater than or equal to a page, we limit the stride
 	 * (and hence alignment) to a page size.
 	 */
-	nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	nslots = ALIGN(alloc_size, IO_TLB_SIZE) >> IO_TLB_SHIFT;
 	if (alloc_size >= PAGE_SIZE)
 		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 	else
@@ -598,7 +598,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 			      enum dma_data_direction dir, unsigned long attrs)
 {
 	unsigned long flags;
-	int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	int i, count, nslots = ALIGN(alloc_size, IO_TLB_SIZE) >> IO_TLB_SHIFT;
 	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 	phys_addr_t orig_addr = io_tlb_orig_addr[index];
 
@@ -649,7 +649,7 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 
 	if (orig_addr == INVALID_PHYS_ADDR)
 		return;
-	orig_addr += (unsigned long)tlb_addr & ((1 << IO_TLB_SHIFT) - 1);
+	orig_addr += (unsigned long)tlb_addr & (IO_TLB_SIZE - 1);
 
 	switch (target) {
 	case SYNC_FOR_CPU:
@@ -707,7 +707,7 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
 
 size_t swiotlb_max_mapping_size(struct device *dev)
 {
-	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
+	return ((size_t)IO_TLB_SIZE) * IO_TLB_SEGSIZE;
 }
 
 bool is_swiotlb_active(void)