From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH 4/7] io-64-nonatomic: Add relaxed accessor variants Date: Thu, 21 Apr 2016 17:18:59 +0100 Message-ID: <20160421161859.GK929@arm.com> References: <44173fd4e8efd27d670cadc6b30e215243a14099.1460391217.git.robin.murphy@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <44173fd4e8efd27d670cadc6b30e215243a14099.1460391217.git.robin.murphy-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Robin Murphy Cc: Arnd Bergmann , Hitoshi Mitake , Christoph Hellwig , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, tchalamarla-M3mlKVOIwJVv6pq1l3V1OdBPR1lH4CV8@public.gmane.org, brian.starkey-5wv7dgnIgG8@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Darren Hart List-Id: iommu@lists.linux-foundation.org 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 > CC: Christoph Hellwig > CC: Darren Hart > CC: Hitoshi Mitake > Signed-off-by: Robin Murphy > --- > 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? Will