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author | Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> | 2012-02-07 02:45:33 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-02-22 00:47:28 (GMT) |
commit | 797a796a13df6b84a4791e57306737059b5b2384 (patch) | |
tree | 400d13deef98fdf3fc893e9e55f208c5716b8ba9 /include/asm-generic/io-64-nonatomic-hi-lo.h | |
parent | 27e74da9800289e69ba907777df1e2085231eff7 (diff) | |
download | linux-797a796a13df6b84a4791e57306737059b5b2384.tar.xz |
asm-generic: architecture independent readq/writeq for 32bit environment
This provides unified readq()/writeq() helper functions for 32-bit
drivers.
For some cases, readq/writeq without atomicity is harmful, and order of
io access has to be specified explicitly. So in this patch, new two
header files which contain non-atomic readq/writeq are added.
- <asm-generic/io-64-nonatomic-lo-hi.h> provides non-atomic readq/
writeq with the order of lower address -> higher address
- <asm-generic/io-64-nonatomic-hi-lo.h> provides non-atomic readq/
writeq with reversed order
This allows us to remove some readq()s that were added drivers when the
default non-atomic ones were removed in commit dbee8a0affd5 ("x86:
remove 32-bit versions of readq()/writeq()")
The drivers which need readq/writeq but can do with the non-atomic ones
must add the line:
#include <asm-generic/io-64-nonatomic-lo-hi.h> /* or hi-lo.h */
But this will be nop in 64-bit environments, and no other #ifdefs are
required. So I believe that this patch can solve the problem of
1. driver-specific readq/writeq
2. atomicity and order of io access
This patch is tested with building allyesconfig and allmodconfig as
ARCH=x86 and ARCH=i386 on top of tip/master.
Cc: Kashyap Desai <Kashyap.Desai@lsi.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Ravi Anand <ravi.anand@qlogic.com>
Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Jason Uhlenkott <juhlenko@akamai.com>
Cc: James Bottomley <James.Bottomley@parallels.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Hitoshi Mitake <h.mitake@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-generic/io-64-nonatomic-hi-lo.h')
-rw-r--r-- | include/asm-generic/io-64-nonatomic-hi-lo.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/include/asm-generic/io-64-nonatomic-hi-lo.h b/include/asm-generic/io-64-nonatomic-hi-lo.h new file mode 100644 index 0000000..a6806a9 --- /dev/null +++ b/include/asm-generic/io-64-nonatomic-hi-lo.h @@ -0,0 +1,28 @@ +#ifndef _ASM_IO_64_NONATOMIC_HI_LO_H_ +#define _ASM_IO_64_NONATOMIC_HI_LO_H_ + +#include <linux/io.h> +#include <asm-generic/int-ll64.h> + +#ifndef readq +static inline __u64 readq(const volatile void __iomem *addr) +{ + const volatile u32 __iomem *p = addr; + u32 low, high; + + high = readl(p + 1); + low = readl(p); + + return low + ((u64)high << 32); +} +#endif + +#ifndef writeq +static inline void writeq(__u64 val, volatile void __iomem *addr) +{ + writel(val >> 32, addr + 4); + writel(val, addr); +} +#endif + +#endif /* _ASM_IO_64_NONATOMIC_HI_LO_H_ */ |