On 21/04/16 17:18, Will Deacon wrote:
On Wed, Apr 13, 2016 at 06:13:00PM +0100, Robin Murphy wrote:Whilst commit 9439eb3ab9d1 ("asm-generic: io: implement relaxed accessor macros as conditional wrappers") makes the *_relaxed forms of I/O accessors universally available to drivers, in cases where writeq() is implemented via the io-64-nonatomic helpers, writeq_relaxed() will end up falling back to writel() regardless of whether writel_relaxed() is available (identically for s/write/read/).Add corresponding relaxed forms of the nonatomic helpers to delegate to the equivalent 32-bit accessors as appropriate. CC: Arnd Bergmann <a...@arndb.de> CC: Christoph Hellwig <h...@lst.de> CC: Darren Hart <dvh...@linux.intel.com> CC: Hitoshi Mitake <mitake.hito...@lab.ntt.co.jp> Signed-off-by: Robin Murphy <robin.mur...@arm.com> --- include/linux/io-64-nonatomic-hi-lo.h | 25 +++++++++++++++++++++++++ include/linux/io-64-nonatomic-lo-hi.h | 25 +++++++++++++++++++++++++ 2 files changed, 50 insertions(+) diff --git a/include/linux/io-64-nonatomic-hi-lo.h b/include/linux/io-64-nonatomic-hi-lo.h index 11d7e84..1a85566 100644 --- a/include/linux/io-64-nonatomic-hi-lo.h +++ b/include/linux/io-64-nonatomic-hi-lo.h @@ -21,6 +21,23 @@ static inline void hi_lo_writeq(__u64 val, volatile void __iomem *addr) writel(val, addr); } +static inline __u64 hi_lo_readq_relaxed(const volatile void __iomem *addr) +{ + const volatile u32 __iomem *p = addr; + u32 low, high; + + high = readl_relaxed(p + 1); + low = readl_relaxed(p); + + return low + ((u64)high << 32); +} + +static inline void hi_lo_writeq_relaxed(__u64 val, volatile void __iomem *addr) +{ + writel_relaxed(val >> 32, addr + 4); + writel_relaxed(val, addr); +}Could we not generate the _relaxed variants with some macro magic?
We _could_ - indeed I started doing that, but then decided that the obfuscation of horrible macro-templated functions wasn't worth saving a couple of hundred bytes in some code that isn't exactly difficult to maintain and has needed touching once in 4 years.
If you did want to go down the macro route, I may as well also generate both lo-hi and hi-lo headers all from a single template, it'd be really clever... <alarm bells> ;)
Robin.
Will
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