sh: cache: define ARCH_DMA_MINALIGN for DMA buffer alignment

Signed-off-by: Anton Staaf <robotboy@chromium.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>

arch/sh/include/asm/cache.h

@@ -6,6 +6,7 @@
 int cache_control(unsigned int cmd);
 
 #define L1_CACHE_BYTES 32
+
 struct __large_struct { unsigned long buf[100]; };
 #define __m(x) (*(struct __large_struct *)(x))
 
@@ -30,6 +31,22 @@ void dcache_invalid_range(u32 start, u32 end)
 			      : "m" (__m(v)));
 	}
 }
+#else
+
+/*
+ * 32-bytes is the largest L1 data cache line size for SH the architecture.  So
+ * it is a safe default for DMA alignment.
+ */
+#define ARCH_DMA_MINALIGN	32
+
 #endif /* CONFIG_SH4 || CONFIG_SH4A */
 
+/*
+ * Use the L1 data cache line size value for the minimum DMA buffer alignment
+ * on SH.
+ */
+#ifndef ARCH_DMA_MINALIGN
+#define ARCH_DMA_MINALIGN	L1_CACHE_BYTES
+#endif
+
 #endif	/* __ASM_SH_CACHE_H */