ARM: dma-mapping: convert DMA direction into IOMMU protection attributes

IOMMU mappings take a prot parameter, identifying the protection bits
to enforce on the newly created mapping (READ or WRITE). The ARM
dma-mapping framework currently just passes 0 as the prot argument,
resulting in faulting mappings.

This patch infers the protection attributes based on the direction of
the DMA transfer.

Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 1d158c2..282aacd 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1637,13 +1637,27 @@ static dma_addr_t arm_coherent_iommu_map_page(struct device *dev, struct page *p
 {
        struct dma_iommu_mapping *mapping = dev->archdata.mapping;
        dma_addr_t dma_addr;
-       int ret, len = PAGE_ALIGN(size + offset);
+       int ret, prot, len = PAGE_ALIGN(size + offset);
 
        dma_addr = __alloc_iova(mapping, len);
        if (dma_addr == DMA_ERROR_CODE)
                return dma_addr;
 
-       ret = iommu_map(mapping->domain, dma_addr, page_to_phys(page), len, 0);
+       switch (dir) {
+       case DMA_BIDIRECTIONAL:
+               prot = IOMMU_READ | IOMMU_WRITE;
+               break;
+       case DMA_TO_DEVICE:
+               prot = IOMMU_READ;
+               break;
+       case DMA_FROM_DEVICE:
+               prot = IOMMU_WRITE;
+               break;
+       default:
+               prot = 0;
+       }
+
+       ret = iommu_map(mapping->domain, dma_addr, page_to_phys(page), len, prot);
        if (ret < 0)
                goto fail;