dma-mapping: unify dma_get_cache_alignment implementations

dma_get_cache_alignment returns the minimum DMA alignment.  Architectures
defines it as ARCH_DMA_MINALIGN (formally ARCH_KMALLOC_MINALIGN).  So we
can unify dma_get_cache_alignment implementations.

Note that some architectures implement dma_get_cache_alignment wrongly.
dma_get_cache_alignment() should return the minimum DMA alignment.  So
fully-coherent architectures should return 1.  This patch also fixes this
issue.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 89b7e1a605b8..e0670a512056 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -142,6 +142,14 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask)
                 return -EIO;
 }
 
+static inline int dma_get_cache_alignment(void)
+{
+#ifdef ARCH_DMA_MINALIGN
+        return ARCH_DMA_MINALIGN;
+#endif
+        return 1;
+}
+
 /* flags for the coherent memory api */
 #define DMA_MEMORY_MAP                  0x01
 #define DMA_MEMORY_IO                   0x02