linux-kernel - Re: [PATCH] soc: qcom: provide mechanism for drivers to access L2 registers

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Date:	Mon, 23 May 2016 18:26:25 -0400
From:	Christopher Covington <cov@...eaurora.org>
To:	Neil Leeder <nleeder@...eaurora.org>,
	Mark Rutland <mark.rutland@....com>
Cc:	David Brown <david.brown@...aro.org>,
	Andy Gross <andy.gross@...aro.org>,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Mark Langsdorf <mlangsdo@...hat.com>,
	Mark Salter <msalter@...hat.com>, Jon Masters <jcm@...hat.com>,
	Timur Tabi <timur@...eaurora.org>, ashwin.chaugule@...aro.org,
	sboyd@...eaurora.org
Subject: Re: [PATCH] soc: qcom: provide mechanism for drivers to access L2
 registers

On 05/23/2016 02:22 PM, Neil Leeder wrote:
> 
> On 5/23/2016 01:25 PM, Mark Rutland wrote:
>> On Fri, May 20, 2016 at 03:13:07PM -0400, Neil Leeder wrote:
>>> L2 registers are accessed using a select register and data
>>> register pair. To prevent multiple concurrent writes to the
>>> select register by independent drivers, the write to the
>>> select register and the associated access of the data register
>>> are protected with a lock. All drivers accessing the L2
>>> registers use the set and get functions provided by
>>> l2-accessors to ensure correct reads and writes to L2 registers.
>>
>> What will this be used for? (i.e. which drivers want to touch the L2
>> registers?).
>>
>> Generally we expect FW to configure the caches and interconnect
>> appropriately.
> 
> The primary use is in the L2 PMU driver, which will be posted shortly.
> 
>>
>>> Signed-off-by: Neil Leeder <nleeder@...eaurora.org>
>>> ---
>>>  drivers/soc/qcom/Kconfig              |  9 +++++
>>>  drivers/soc/qcom/Makefile             |  1 +
>>>  drivers/soc/qcom/l2-accessors.c       | 66 +++++++++++++++++++++++++++++++++++
>>>  include/linux/soc/qcom/l2-accessors.h | 27 ++++++++++++++
>>>  4 files changed, 103 insertions(+)
>>>  create mode 100644 drivers/soc/qcom/l2-accessors.c
>>>  create mode 100644 include/linux/soc/qcom/l2-accessors.h
>>
>> These are awfully generic file names (and function names). Which SoCs
>> does this apply to?
>>
>> It would be good to give these more specific names.
> 
> It's under soc/qcom, and dependent on ARCH_QCOM and (in v2) also on ARM64. It applies to all QCOM ARM64 SoCs.
> Given that it can only be used in a QCOM driver, and the include path has qcom in it, I'd
> prefer not to add redundancy by adding another qcom in there.

They ended up calling the pinctrl file qcom/pinctrl/qdf2xxx.c.

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8f1338cd80648adf5434798f5393ad7c55d10848

Regards,
Cov

-- 
Qualcomm Innovation Center, Inc.
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