From: robin.murphy@arm•com (Robin Murphy)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4/7] io-64-nonatomic: Add relaxed accessor variants
Date: Fri, 22 Apr 2016 18:08:46 +0100 [thread overview]
Message-ID: <571A5A9E.7040305@arm.com> (raw)
In-Reply-To: <20160421161859.GK929@arm.com>
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 <arnd@arndb•de>
>> CC: Christoph Hellwig <hch@lst•de>
>> CC: Darren Hart <dvhart@linux•intel.com>
>> CC: Hitoshi Mitake <mitake.hitoshi@lab•ntt.co.jp>
>> Signed-off-by: Robin Murphy <robin.murphy@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
>
next prev parent reply other threads:[~2016-04-22 17:08 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-13 17:12 [PATCH 0/7] arm-smmu: Implementation and context format differentiation Robin Murphy
2016-04-13 17:12 ` [PATCH 1/7] iommu/arm-smmu: Differentiate specific implementations Robin Murphy
2016-04-13 21:15 ` Chalamarla, Tirumalesh
2016-04-13 17:12 ` [PATCH 2/7] iommu/arm-smmu: Convert ThunderX workaround to new method Robin Murphy
2016-04-13 21:16 ` Chalamarla, Tirumalesh
2016-04-13 17:12 ` [PATCH 3/7] iommu/arm-smmu: Work around MMU-500 prefetch errata Robin Murphy
2016-04-21 16:15 ` Will Deacon
2016-04-21 16:16 ` Will Deacon
2016-04-13 17:13 ` [PATCH 4/7] io-64-nonatomic: Add relaxed accessor variants Robin Murphy
2016-04-21 16:18 ` Will Deacon
2016-04-22 17:08 ` Robin Murphy [this message]
2016-04-25 13:32 ` Will Deacon
2016-04-25 15:21 ` Arnd Bergmann
2016-04-25 15:28 ` Robin Murphy
2016-04-25 15:41 ` Arnd Bergmann
2016-04-25 16:11 ` Will Deacon
2016-04-25 16:11 ` Arnd Bergmann
2016-04-26 10:38 ` [PATCH v2] " Robin Murphy
2016-04-13 17:13 ` [PATCH 5/7] iommu/arm-smmu: Tidy up 64-bit/atomic I/O accesses Robin Murphy
2016-04-13 17:13 ` [PATCH 6/7] iommu/arm-smmu: Decouple context format from kernel config Robin Murphy
2016-04-21 16:30 ` Will Deacon
2016-04-22 17:38 ` Robin Murphy
2016-04-25 11:02 ` Will Deacon
2016-04-25 13:14 ` Robin Murphy
2016-04-25 13:41 ` Will Deacon
2016-04-25 16:21 ` Robin Murphy
2016-04-28 16:12 ` [PATCH v2] " Robin Murphy
2016-04-13 17:13 ` [PATCH 7/7] iommu/arm-smmu: Support SMMUv1 64KB supplement Robin Murphy
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