ARC: [BE] readl()/writel() to work in Big Endian CPU configuration (f778cc65) · Commits · 戴 / test

read{l,w}() write{l,w}() primitives should use le{16,32}_to_cpu() and cpu_to_le{16,32}() respectively to ensure device registers are read correctly in Big Endian CPU configuration. Per Arnd Bergmann | Most drivers using readl() or readl_relaxed() expect those to perform byte | swaps on big-endian architectures, as the registers tend to be fixed endian This was needed for getting UART to work correctly on a Big Endian ARC. The ARC accessors originally were fine, and the bug got introduced inadventently by commit ("ARCv2: barriers") Fixes: ("ARCv2: barriers") Link: http://lkml.kernel.org/r/201603100845.30602.arnd@arndb.de Cc: Alexey Brodkin <abrodkin@synopsys.com> Cc: stable@vger.kernel.org [4.2+] Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by:

Lada Trimasova <ltrimas@synopsys.com> [vgupta: beefed up changelog, added Fixes/stable tags] Signed-off-by:

Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/io.h

+13 −5

Original line number	Diff line number	Diff line
		@@ -129,15 +129,23 @@ static inline void __raw_writel(u32 w, volatile void __iomem *addr)
		#define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); })

		/*
		* Relaxed API for drivers which can handle any ordering themselves
		* Relaxed API for drivers which can handle barrier ordering themselves
		*
		* Also these are defined to perform little endian accesses.
		* To provide the typical device register semantics of fixed endian,
		* swap the byte order for Big Endian
		*
		* http://lkml.kernel.org/r/201603100845.30602.arnd@arndb.de
		*/
		#define readb_relaxed(c) __raw_readb(c)
		#define readw_relaxed(c) __raw_readw(c)
		#define readl_relaxed(c) __raw_readl(c)
		#define readw_relaxed(c) ({ u16 __r = le16_to_cpu((__force __le16) \
		__raw_readw(c)); __r; })
		#define readl_relaxed(c) ({ u32 __r = le32_to_cpu((__force __le32) \
		__raw_readl(c)); __r; })

		#define writeb_relaxed(v,c) __raw_writeb(v,c)
		#define writew_relaxed(v,c) __raw_writew(v,c)
		#define writel_relaxed(v,c) __raw_writel(v,c)
		#define writew_relaxed(v,c) __raw_writew((__force u16) cpu_to_le16(v),c)
		#define writel_relaxed(v,c) __raw_writel((__force u32) cpu_to_le32(v),c)

		#include <asm-generic/io.h>

Admin message