linux-kernel - Re: Use of pinctrl-single for external device over I2C

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Date:	Tue, 30 Jun 2015 13:28:15 +0530
From:	Vaibhav Hiremath <vaibhav.hiremath@...aro.org>
To:	Tony Lindgren <tony@...mide.com>
CC:	Linus Walleij <linus.walleij@...aro.org>, lee.jones@...aro.org,
	sameo@...ux.intel.com, linux-gpio@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-kernel@...r.kernel.org
Subject: Re: Use of pinctrl-single for external device over I2C



On Tuesday 30 June 2015 01:16 PM, Vaibhav Hiremath wrote:
>
>
> On Thursday 25 June 2015 11:16 AM, Vaibhav Hiremath wrote:
>>
>>
>> On Thursday 25 June 2015 10:08 AM, Tony Lindgren wrote:
>>> * Vaibhav Hiremath <vaibhav.hiremath@...aro.org> [150624 10:12]:
>>>>
>>>> I do not like this, as this is not HW feature, so DT may not be right
>>>> approach.
>>>>
>>>> So I will dig more from either runtime or Compile time option to use
>>>> regmap_ Vs raw read/writes.
>>>
>>> Can't you just check if the pinctrl node has compatible = "syscon"
>>> property?
>>>
>>> A compile time option won't work for sure. I don't know what you
>>> would check at runtime as you do not know what the bus is behind
>>> syscon.
>>>
>>
>> Although, I haven't gone through syscon, but not sure whether syscon
>> would be useful.
>>
>> As you rightly stated, we need to know the bus behind regmap.
>>
>
> Trying to understand what is the right way of doing pinctrl of external
> device on board,
>
> I feel it would not be good idea to pollute pinctrl-single driver, and
> also I am still not able to figure out how can I have access to bus
> behind regmap.
>
>
> How about having separate driver (generic for all I2C), say pinctrl-
> i2c.c, which is i2c_client driver and would support pinctrl and pinmux
> on I2C client device.
>

I mean, part of mfd here (mfd_cell)

>
> The current usecase which I have is pretty simple in nature,
>
> 88PM860 has few GPIO pins which can be configured to different
> functionality, based on board design.
> In most of the cases they are one/init/boot time settings.
>
> GPIO_0:
> =======
>    000 = GPIO input mode
>    001 = GPIO output mode
>    010 = SLEEPOUTN mirror mode
>    011 = Buck4 FPWM enable
>    100 = 32 Khz output buffer mode
>    101 = PMICINTN output mode
>    110 = HW_RESET1 mode
>    111 = HW_RESET2 mode
>
>
> Thanks,
> Vaibhav
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