[RFC/PATCH 2/9] arm: dma-mapping: Support IOMMU mappings spanning the full 32 bits range

[Laurent Pinchart]

The arm_iommu_create_mapping() function takes the IOMMU mapping size as
a size_t, limiting the size to 4GB - 1 on 32 bit platforms while most
bus masters would support the full 32 bits range. Fix this by passing
the size as a 64 bits integer, and limiting it to 4GB for now.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
---
 arch/arm/include/asm/dma-iommu.h |  2 +-
 arch/arm/mm/dma-mapping.c        | 12 +++---------
 2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h
index 8e3fcb924db6..2ef282f96651 100644
--- a/arch/arm/include/asm/dma-iommu.h
+++ b/arch/arm/include/asm/dma-iommu.h
@@ -25,7 +25,7 @@ struct dma_iommu_mapping {
 };
 
 struct dma_iommu_mapping *
-arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size);
+arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, u64 size);
 
 void arm_iommu_release_mapping(struct dma_iommu_mapping *mapping);
 
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 7aa5e339a596..c69e216a0cf9 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1878,7 +1878,7 @@ struct dma_map_ops iommu_coherent_ops = {
  * arm_iommu_attach_device function.
  */
 struct dma_iommu_mapping *
-arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size)
+arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, u64 size)
 {
 	unsigned int bits = size >> PAGE_SHIFT;
 	unsigned int bitmap_size = BITS_TO_LONGS(bits) * sizeof(long);
@@ -1886,7 +1886,8 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size)
 	int extensions = 1;
 	int err = -ENOMEM;
 
-	if (!bitmap_size)
+	/* Limit the size to 4GB for now. */
+	if (!size || size > (1ULL << 32))
 		return ERR_PTR(-EINVAL);
 
 	if (bitmap_size > PAGE_SIZE) {
@@ -2057,13 +2058,6 @@ static bool arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	if (!iommu)
 		return false;
 
-	/*
-	 * currently arm_iommu_create_mapping() takes a max of size_t
-	 * for size param. So check this limit for now.
-	 */
-	if (size > SIZE_MAX)
-		return false;
-
 	mapping = arm_iommu_create_mapping(dev->bus, dma_base, size);
 	if (IS_ERR(mapping)) {
 		pr_warn("Failed to create %llu-byte IOMMU mapping for device %s\n",
-- 
2.3.6