iommu: add dma_get_mask helper function

Several IOMMUs do the same thing to get the dma_mask of a device. This
adds a helper function to do the same thing to sweep them.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 6ed50c1642f1..0dba7433af18 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -63,6 +63,13 @@ static inline int is_buffer_dma_capable(u64 mask, dma_addr_t addr, size_t size)
 #define dma_sync_single         dma_sync_single_for_cpu
 #define dma_sync_sg             dma_sync_sg_for_cpu
 
+static inline u64 dma_get_mask(struct device *dev)
+{
+        if (dev->dma_mask && *dev->dma_mask)
+                return *dev->dma_mask;
+        return DMA_32BIT_MASK;
+}
+
 extern u64 dma_get_required_mask(struct device *dev);
 
 static inline unsigned int dma_get_max_seg_size(struct device *dev)