Re: [PATCH 02/12] dt-bindings: document s3c24xx controller for external clock output

From: Tomasz Figa <tomasz.figa@gmail.com>
To: "Heiko Stübner" <heiko@sntech.de>
Cc: Kukjin Kim <kgene.kim@samsung.com>,
	t.figa@samsung.com, mturquette@linaro.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org,
	Rob Herring <rob.herring@calxeda.com>,
	Pawel Moll <pawel.moll@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 02/12] dt-bindings: document s3c24xx controller for external clock output
Date: Sun, 16 Feb 2014 21:51:04 +0100	[thread overview]
Message-ID: <530124B8.9050209@gmail.com> (raw)
In-Reply-To: <5620516.DA2mHk7Kko@phil>

On 16.02.2014 21:33, Heiko Stübner wrote:
> Am Sonntag, 9. Februar 2014, 02:54:40 schrieb Tomasz Figa:
>> Hi Heiko,
>>
>> On 13.12.2013 13:59, Heiko Stübner wrote:
>>> The clock settings are distributed over a regular register and parts
>>> of the misccr register.
>>>
>>> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
>>> ---
>>>
>>>    .../bindings/clock/samsung,s3c2410-dclk.txt        |   53
>>>    ++++++++++++++++++++ 1 file changed, 53 insertions(+)
>>>    create mode 100644
>>>    Documentation/devicetree/bindings/clock/samsung,s3c2410-dclk.txt>
>>> diff --git
>>> a/Documentation/devicetree/bindings/clock/samsung,s3c2410-dclk.txt
>>> b/Documentation/devicetree/bindings/clock/samsung,s3c2410-dclk.txt new
>>> file mode 100644
>>> index 0000000..0a1f7b1
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/clock/samsung,s3c2410-dclk.txt
>>> @@ -0,0 +1,53 @@
>>> +* Samsung S3C24XX External Clock Output Controller
>>> +
>>> +The S3C24XX series can generate clock signals on two clock output pads.
>>> +The clock binding described here is applicable to all SoCs in
>>> +the s3c24x family.
>>> +
>>> +Required Properties:
>>> +
>>> +- compatible: should be one of the following.
>>> +  - "samsung,s3c2410-dclk" - controller in S3C2410 SoCs.
>>> +  - "samsung,s3c2412-dclk" - controller in S3C2412 SoCs.
>>> +  - "samsung,s3c2440-dclk" - controller in S3C2440 and S3C2442 SoCs.
>>> +  - "samsung,s3c2443-dclk" - controller in S3C2443 and later SoCs.
>>> +- reg: physical base address of the controller and length of memory
>>> mapped
>>> +  region.
>>> +- #clock-cells: should be 1.
>>> +- samsung,misccr: phandle to the syscon managing the misccr register,
>>> which +  holds configuration settings for different soc-components
>>> (clocks, usb, ...).
>> Hmm, looking at the datasheet, DCLK and CLKOUT registers seem to be part
>> of the pin controller. I wonder if there is really a need for different
>> driver and device node to handle them.
>>
>> Could this be simply made a part of the s3c24xx pinctrl driver,
>> extending it to register also a clock provider under the same DT node?
>
> it could, but of course the non-dt platforms would not be able to use it in
> this case.

Hmm, that's true.

> So I guess, we could get rid of this dt binding, implement the clkout handling
> in the pinctrl driver for dt platforms, but use the platform-driver this
> binding described for the time we're still handling non-dt s3c24xx machines.

I guess you could make this a separate driver that would be instantiated 
by pinctrl driver registering another platform device in DT case and a 
static platform device registered by board files in non-DT case.

Best regards,
Tomasz