linux-kernel - [PATCH v3 01/17] asm-generic: io: implement relaxed accessor macros as conditional wrappers

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Date:	Wed, 24 Sep 2014 18:17:20 +0100
From:	Will Deacon <will.deacon@....com>
To:	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	arnd@...db.de, benh@...nel.crashing.org, chris@...kel.net,
	cmetcalf@...era.com, davem@...emloft.net, deller@....de,
	dhowells@...hat.com, geert@...ux-m68k.org,
	heiko.carstens@...ibm.com, hpa@...or.com, jcmvbkbc@...il.com,
	jesper.nilsson@...s.com, mingo@...hat.com, monstr@...str.eu,
	paulmck@...ux.vnet.ibm.com, rdunlap@...radead.org,
	sam@...nborg.org, schwidefsky@...ibm.com, starvik@...s.com,
	takata@...ux-m32r.org, tglx@...utronix.de, tony.luck@...el.com,
	daniel.thompson@...aro.org, broonie@...aro.org,
	linux@....linux.org.uk, Will Deacon <will.deacon@....com>
Subject: [PATCH v3 01/17] asm-generic: io: implement relaxed accessor macros as conditional wrappers

{read,write}{b,w,l,q}_relaxed are implemented by some architectures in
order to permit memory-mapped I/O accesses with weaker barrier semantics
than the non-relaxed variants.

This patch adds wrappers to asm-generic so that drivers can rely on the
relaxed accessors being available, even if they don't always provide
weaker ordering guarantees. Since some architectures both include
asm-generic/io.h and define some relaxed accessors, the definitions here
are conditional for the time being.

Cc: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Will Deacon <will.deacon@....com>
---
 include/asm-generic/io.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 975e1cc75edb..9ccedeb06522 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -53,18 +53,27 @@ static inline u32 __raw_readl(const volatile void __iomem *addr)
 #endif
 
 #define readb __raw_readb
+#ifndef readb_relaxed
+#define readb_relaxed readb
+#endif
 
 #define readw readw
 static inline u16 readw(const volatile void __iomem *addr)
 {
 	return __le16_to_cpu(__raw_readw(addr));
 }
+#ifndef readw_relaxed
+#define readw_relaxed readw
+#endif
 
 #define readl readl
 static inline u32 readl(const volatile void __iomem *addr)
 {
 	return __le32_to_cpu(__raw_readl(addr));
 }
+#ifndef readl_relaxed
+#define readl_relaxed readl
+#endif
 
 #ifndef __raw_writeb
 static inline void __raw_writeb(u8 b, volatile void __iomem *addr)
@@ -88,8 +97,19 @@ static inline void __raw_writel(u32 b, volatile void __iomem *addr)
 #endif
 
 #define writeb __raw_writeb
+#ifndef writeb_relaxed
+#define writeb_relaxed writeb
+#endif
+
 #define writew(b,addr) __raw_writew(__cpu_to_le16(b),addr)
+#ifndef writew_relaxed
+#define writew_relaxed writew
+#endif
+
 #define writel(b,addr) __raw_writel(__cpu_to_le32(b),addr)
+#ifndef writel_relaxed
+#define writel_relaxed writel
+#endif
 
 #ifdef CONFIG_64BIT
 #ifndef __raw_readq
@@ -104,6 +124,9 @@ static inline u64 readq(const volatile void __iomem *addr)
 {
 	return __le64_to_cpu(__raw_readq(addr));
 }
+#ifndef readq_relaxed
+#define readq_relaxed readq
+#endif
 
 #ifndef __raw_writeq
 static inline void __raw_writeq(u64 b, volatile void __iomem *addr)
@@ -113,6 +136,9 @@ static inline void __raw_writeq(u64 b, volatile void __iomem *addr)
 #endif
 
 #define writeq(b, addr) __raw_writeq(__cpu_to_le64(b), addr)
+#ifndef writeq_relaxed
+#define writeq_relaxed writeq
+#endif
 #endif /* CONFIG_64BIT */
 
 #ifndef PCI_IOBASE
-- 
2.1.0

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