[PATCH] riscv: Avoid io read/write cause wrong result

[Nick Hu <nick.hu@sifive.com>]

io read/write may cause wrong result because they may read/write data
from/to register instead of memory. Add 'volatile' to avoid it.

Signed-off-by: Nick Hu <nick.hu@sifive.com>
---
 arch/riscv/include/asm/io.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index acf5a96449..3540773c4f 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -44,15 +44,15 @@ static inline phys_addr_t map_to_sysmem(const void *ptr)
  * read/writes.  We define __arch_*[bl] here, and leave __arch_*w
  * to the architecture specific code.
  */
-#define __arch_getb(a)			(*(unsigned char *)(a))
-#define __arch_getw(a)			(*(unsigned short *)(a))
-#define __arch_getl(a)			(*(unsigned int *)(a))
-#define __arch_getq(a)			(*(unsigned long long *)(a))
-
-#define __arch_putb(v, a)		(*(unsigned char *)(a) = (v))
-#define __arch_putw(v, a)		(*(unsigned short *)(a) = (v))
-#define __arch_putl(v, a)		(*(unsigned int *)(a) = (v))
-#define __arch_putq(v, a)		(*(unsigned long long *)(a) = (v))
+#define __arch_getb(a)			(*(volatile unsigned char *)(a))
+#define __arch_getw(a)			(*(volatile unsigned short *)(a))
+#define __arch_getl(a)			(*(volatile unsigned int *)(a))
+#define __arch_getq(a)			(*(volatile unsigned long long *)(a))
+
+#define __arch_putb(v, a)		(*(volatile unsigned char *)(a) = (v))
+#define __arch_putw(v, a)		(*(volatile unsigned short *)(a) = (v))
+#define __arch_putl(v, a)		(*(volatile unsigned int *)(a) = (v))
+#define __arch_putq(v, a)		(*(volatile unsigned long long *)(a) = (v))
 
 #define __raw_writeb(v, a)		__arch_putb(v, a)
 #define __raw_writew(v, a)		__arch_putw(v, a)
-- 
2.31.1