common.h: Introduce DEFINE_CACHE_ALIGN_BUFFER

This is the out-of-function-scope counterpart of
ALLOC_CACHE_ALIGN_BUFFER.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@ti.com>
[ilya.yanok]: added missing <linux/compiler.h> include and
{DEFINE,ALLOC}_ALIGN_BUFFER macros allowing explicit alignment
specification.
Signed-off-by: Ilya Yanok <ilya.yanok@cogentembedded.com>

include/common.h

@@ -39,6 +39,7 @@ typedef volatile unsigned char	vu_char;
 #include <linux/bitops.h>
 #include <linux/types.h>
 #include <linux/string.h>
+#include <linux/compiler.h>
 #include <asm/ptrace.h>
 #include <stdarg.h>
 #if defined(CONFIG_PCI) && (defined(CONFIG_4xx) && !defined(CONFIG_AP1000))
@@ -944,11 +945,25 @@ int cpu_release(int nr, int argc, char * const argv[]);
  * of a function scoped static buffer.  It can not be used to create a cache
  * line aligned global buffer.
  */
+#define ALLOC_ALIGN_BUFFER(type, name, size, align)			\
+	char __##name[ROUND(size * sizeof(type), align) + (align - 1)];	\
+									\
+	type *name = (type *) ALIGN((uintptr_t)__##name, align)
 #define ALLOC_CACHE_ALIGN_BUFFER(type, name, size)			\
-	char __##name[ROUND(size * sizeof(type), ARCH_DMA_MINALIGN) +	\
-		      ARCH_DMA_MINALIGN - 1];				\
+	ALLOC_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
+
+/*
+ * DEFINE_CACHE_ALIGN_BUFFER() is similar to ALLOC_CACHE_ALIGN_BUFFER, but it's
+ * purpose is to allow allocating aligned buffers outside of function scope.
+ * Usage of this macro shall be avoided or used with extreme care!
+ */
+#define DEFINE_ALIGN_BUFFER(type, name, size, align)			\
+	static char __##name[roundup(size * sizeof(type), align)]	\
+			__aligned(align);				\
 									\
-	type *name = (type *) ALIGN((uintptr_t)__##name, ARCH_DMA_MINALIGN)
+	static type *name = (type *)__##name
+#define DEFINE_CACHE_ALIGN_BUFFER(type, name, size)			\
+	DEFINE_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
 
 /* Pull in stuff for the build system */
 #ifdef DO_DEPS_ONLY