diff options
| author | Alexander Holler <holler@ahsoftware.de> | 2011-01-09 12:19:44 +0000 |
|---|---|---|
| committer | Albert Aribaud <albert.aribaud@free.fr> | 2011-02-02 00:54:44 +0100 |
| commit | 3c0659b535b075be124c3d2a0714e55e65c46737 (patch) | |
| tree | e8d99c2dff1e0d6afdaf83b6b5301dbe47ce7e5b /arch | |
| parent | 3c152165c78408e44845f2d08469db887f050e43 (diff) | |
ARM: Avoid compiler optimization for readb, writeb and friends.
gcc 4.5.1 seems to ignore (at least some) volatile definitions,
avoid that as done in the kernel.
Reading C99 6.7.3 8 and the comment 114) there, I think it is a bug of that
gcc version to ignore the volatile type qualifier used e.g. in __arch_getl().
Anyway, using a definition as in the kernel headers avoids such optimizations when
gcc 4.5.1 is used.
Maybe the headers as used in the current linux-kernel should be used,
but to avoid large changes, I've just added a small change to the current headers.
Signed-off-by: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>
Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Alessandro Rubini <rubini-list@gnudd.com>
Tested-by: Thomas Weber <weber@corscience.de>
Acked-by: Alexander Holler <holler@ahsoftware.de>
Tested-by: Alexander Holler <holler@ahsoftware.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/io.h | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index ff1518eb0..3886f1589 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -117,21 +117,29 @@ extern inline void __raw_readsl(unsigned int addr, void *data, int longlen) *buf++ = __arch_getl(addr); } -#define __raw_writeb(v,a) __arch_putb(v,a) -#define __raw_writew(v,a) __arch_putw(v,a) -#define __raw_writel(v,a) __arch_putl(v,a) +#define __raw_writeb(v,a) __arch_putb(v,a) +#define __raw_writew(v,a) __arch_putw(v,a) +#define __raw_writel(v,a) __arch_putl(v,a) -#define __raw_readb(a) __arch_getb(a) -#define __raw_readw(a) __arch_getw(a) -#define __raw_readl(a) __arch_getl(a) +#define __raw_readb(a) __arch_getb(a) +#define __raw_readw(a) __arch_getw(a) +#define __raw_readl(a) __arch_getl(a) -#define writeb(v,a) __arch_putb(v,a) -#define writew(v,a) __arch_putw(v,a) -#define writel(v,a) __arch_putl(v,a) +/* + * TODO: The kernel offers some more advanced versions of barriers, it might + * have some advantages to use them instead of the simple one here. + */ +#define dmb() __asm__ __volatile__ ("" : : : "memory") +#define __iormb() dmb() +#define __iowmb() dmb() + +#define writeb(v,c) ({ __iowmb(); __arch_putb(v,c); v; }) +#define writew(v,c) ({ __iowmb(); __arch_putw(v,c); v; }) +#define writel(v,c) ({ __iowmb(); __arch_putl(v,c); v; }) -#define readb(a) __arch_getb(a) -#define readw(a) __arch_getw(a) -#define readl(a) __arch_getl(a) +#define readb(c) ({ u8 __v = __arch_getb(c); __iormb(); __v; }) +#define readw(c) ({ u16 __v = __arch_getw(c); __iormb(); __v; }) +#define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; }) /* * The compiler seems to be incapable of optimising constants |