ARC: IO: add volatile to accessors

We must use 'volatile' in C-version read/write IO accessors
implementation to avoid merging several reads (writes) into
one read (write), or optimizing them out by compiler.

Fixes commit 07906b3dad15 ("ARC: Switch to generic accessors")

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

diff --git a/arch/arc/include/asm/io.h b/arch/arc/include/asm/io.h
index 70d050590de4d4b544cd69dfb41b9b4975d9cf29..1f1ae889f3a4e86fbd828ab8008ecb6c806bd0d0 100644 (file)
--- a/arch/arc/include/asm/io.h
+++ b/arch/arc/include/asm/io.h
@@ -54,15 +54,21 @@ static inline void sync(void)
        /* Not yet implemented */
 }
 
-#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))
+/*
+ * We must use 'volatile' in C-version read/write IO accessors implementation
+ * to avoid merging several reads (writes) into one read (write), or optimizing
+ * them out by compiler.
+ */
+#define __arch_getb(a)         (*(volatile u8 *)(a))
+#define __arch_getw(a)         (*(volatile u16 *)(a))
+#define __arch_getl(a)         (*(volatile u32 *)(a))
+#define __arch_getq(a)         (*(volatile u64 *)(a))
+
+#define __arch_putb(v, a)      (*(volatile u8 *)(a) = (v))
+#define __arch_putw(v, a)      (*(volatile u16 *)(a) = (v))
+#define __arch_putl(v, a)      (*(volatile u32 *)(a) = (v))
+#define __arch_putq(v, a)      (*(volatile u64 *)(a) = (v))
+
 
 #define __raw_writeb(v, a)     __arch_putb(v, a)
 #define __raw_writew(v, a)     __arch_putw(v, a)