ARM: dma-mapping: add support for DMA_ATTR_SKIP_CPU_SYNC attribute
This patch adds support for DMA_ATTR_SKIP_CPU_SYNC attribute for
dma_(un)map_(single,page,sg) functions family. It lets dma mapping clients
to create a mapping for the buffer for the given device without performing
a CPU cache synchronization. CPU cache synchronization can be skipped for
the buffers which it is known that they are already in 'device' domain (CPU
caches have been already synchronized or there are only coherent mappings
for the buffer). For advanced users only, please use it with care.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 51278ed..b30ba0a 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -73,7 +73,7 @@
unsigned long offset, size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs)
{
- if (!arch_is_coherent())
+ if (!arch_is_coherent() && !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
__dma_page_cpu_to_dev(page, offset, size, dir);
return pfn_to_dma(dev, page_to_pfn(page)) + offset;
}
@@ -96,7 +96,7 @@
size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs)
{
- if (!arch_is_coherent())
+ if (!arch_is_coherent() && !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
__dma_page_dev_to_cpu(pfn_to_page(dma_to_pfn(dev, handle)),
handle & ~PAGE_MASK, size, dir);
}
@@ -1207,7 +1207,7 @@
*/
static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
size_t size, dma_addr_t *handle,
- enum dma_data_direction dir)
+ enum dma_data_direction dir, struct dma_attrs *attrs)
{
struct dma_iommu_mapping *mapping = dev->archdata.mapping;
dma_addr_t iova, iova_base;
@@ -1226,7 +1226,8 @@
phys_addr_t phys = page_to_phys(sg_page(s));
unsigned int len = PAGE_ALIGN(s->offset + s->length);
- if (!arch_is_coherent())
+ if (!arch_is_coherent() &&
+ !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);
@@ -1273,7 +1274,7 @@
if (s->offset || (size & ~PAGE_MASK) || size + s->length > max) {
if (__map_sg_chunk(dev, start, size, &dma->dma_address,
- dir) < 0)
+ dir, attrs) < 0)
goto bad_mapping;
dma->dma_address += offset;
@@ -1286,7 +1287,7 @@
}
size += s->length;
}
- if (__map_sg_chunk(dev, start, size, &dma->dma_address, dir) < 0)
+ if (__map_sg_chunk(dev, start, size, &dma->dma_address, dir, attrs) < 0)
goto bad_mapping;
dma->dma_address += offset;
@@ -1320,7 +1321,8 @@
if (sg_dma_len(s))
__iommu_remove_mapping(dev, sg_dma_address(s),
sg_dma_len(s));
- if (!arch_is_coherent())
+ if (!arch_is_coherent() &&
+ !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
__dma_page_dev_to_cpu(sg_page(s), s->offset,
s->length, dir);
}
@@ -1382,7 +1384,7 @@
dma_addr_t dma_addr;
int ret, len = PAGE_ALIGN(size + offset);
- if (!arch_is_coherent())
+ if (!arch_is_coherent() && !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
__dma_page_cpu_to_dev(page, offset, size, dir);
dma_addr = __alloc_iova(mapping, len);
@@ -1421,7 +1423,7 @@
if (!iova)
return;
- if (!arch_is_coherent())
+ if (!arch_is_coherent() && !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
__dma_page_dev_to_cpu(page, offset, size, dir);
iommu_unmap(mapping->domain, iova, len);