ARM: dma-mapping: Always pass proper prot flags to iommu_map()

... otherwise it is impossible for the low level iommu driver to
figure out which pte flags should be used.

In __map_sg_chunk we can derive the flags from dma_data_direction.

In __iommu_create_mapping we should treat the memory like
DMA_BIDIRECTIONAL and pass both IOMMU_READ and IOMMU_WRITE to
iommu_map.
__iommu_create_mapping is used during dma_alloc_coherent (via
arm_iommu_alloc_attrs).  AFAIK dma_alloc_coherent is responsible for
allocation _and_ mapping.  I think this implies that access to the
mapped pages should be allowed.

Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andreas Herrmann <andreas.herrmann@calxeda.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

1 files changed, 28 insertions, 15 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f5e1a8471714..1272ed202dde 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1232,7 +1232,8 @@ __iommu_create_mapping(struct device *dev, struct page **pages, size_t size)
                                 break;
 
                 len = (j - i) << PAGE_SHIFT;
-                ret = iommu_map(mapping->domain, iova, phys, len, 0);
+                ret = iommu_map(mapping->domain, iova, phys, len,
+                                IOMMU_READ|IOMMU_WRITE);
                 if (ret < 0)
                         goto fail;
                 iova += len;
@@ -1431,6 +1432,27 @@ static int arm_iommu_get_sgtable(struct device *dev, struct sg_table *sgt,
                                          GFP_KERNEL);
 }
 
+static int __dma_direction_to_prot(enum dma_data_direction dir)
+{
+        int prot;
+
+        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;
+        }
+
+        return prot;
+}
+
 /*
  * Map a part of the scatter-gather list into contiguous io address space
  */
@@ -1444,6 +1466,7 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
         int ret = 0;
         unsigned int count;
         struct scatterlist *s;
+        int prot;
 
         size = PAGE_ALIGN(size);
         *handle = DMA_ERROR_CODE;
@@ -1460,7 +1483,9 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
                         !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
                         __dma_page_cpu_to_dev(sg_page(s), s->offset, s->length, dir);
 
-                ret = iommu_map(mapping->domain, iova, phys, len, 0);
+                prot = __dma_direction_to_prot(dir);
+
+                ret = iommu_map(mapping->domain, iova, phys, len, prot);
                 if (ret < 0)
                         goto fail;
                 count += len >> PAGE_SHIFT;
@@ -1665,19 +1690,7 @@ static dma_addr_t arm_coherent_iommu_map_page(struct device *dev, struct page *p
         if (dma_addr == DMA_ERROR_CODE)
                 return dma_addr;
 
-        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;
-        }
+        prot = __dma_direction_to_prot(dir);
 
         ret = iommu_map(mapping->domain, dma_addr, page_to_phys(page), len, prot);
         if (ret < 0)