asm-generic/io.h: allow barriers in io{read,write}{16,32}be (7a1aedba) · Commits · 戴 / test

While reviewing the addition of io{read,write}64be accessors, Arnd -finds a potential problem: "If an architecture overrides readq/writeq to have barriers but does not override ioread64be/iowrite64be, this will lack the barriers and behave differently from the little-endian version. I think the only affected architecture is ARC, since ARM and ARM64 both override the big-endian accessors to have the correct barriers, and all others don't use barriers at all." -suggests a fix for the same problem in existing code (16/32-bit accessors); the fix leads "to a double-swap on architectures that don't override the io{read,write}{16,32}be accessors, but it will work correctly on all architectures without them having to override these accessors." Suggested-by:

Arnd Bergmann <arnd@arndb.de> Acked-by:

Arnd Bergmann <arnd@arndb.de> Signed-off-by:

Horia Geantă <horia.geanta@nxp.com> Signed-off-by:

Herbert Xu <herbert@gondor.apana.org.au>

include/asm-generic/io.h

+4 −4

Original line number	Diff line number	Diff line
		@@ -613,7 +613,7 @@ static inline void iowrite32(u32 value, volatile void __iomem *addr)
		#define ioread16be ioread16be
		static inline u16 ioread16be(const volatile void __iomem *addr)
		{
		return __be16_to_cpu(__raw_readw(addr));
		return swab16(readw(addr));
		}
		#endif

		@@ -621,7 +621,7 @@ static inline u16 ioread16be(const volatile void __iomem *addr)
		#define ioread32be ioread32be
		static inline u32 ioread32be(const volatile void __iomem *addr)
		{
		return __be32_to_cpu(__raw_readl(addr));
		return swab32(readl(addr));
		}
		#endif

		@@ -629,7 +629,7 @@ static inline u32 ioread32be(const volatile void __iomem *addr)
		#define iowrite16be iowrite16be
		static inline void iowrite16be(u16 value, void volatile __iomem *addr)
		{
		__raw_writew(__cpu_to_be16(value), addr);
		writew(swab16(value), addr);
		}
		#endif

		@@ -637,7 +637,7 @@ static inline void iowrite16be(u16 value, void volatile __iomem *addr)
		#define iowrite32be iowrite32be
		static inline void iowrite32be(u32 value, volatile void __iomem *addr)
		{
		__raw_writel(__cpu_to_be32(value), addr);
		writel(swab32(value), addr);
		}
		#endif

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