Re: [rtc-linux] [PATCH V2 3/5] gpio: add support for AMS AS3722 gpiodriver

[Laxman Dewangan]

On Monday 23 September 2013 02:56 PM, Linus Walleij wrote:
> On Mon, Sep 23, 2013 at 10:55 AM, Laxman Dewangan <ldewangan@xxxxxxxxxx> wrote:
> > On Monday 23 September 2013 01:36 PM, Linus Walleij wrote:
> > > This is pin control. Do not try to shoehorn pin control drivers into
> > > the GPIO subsystem. Take a good day off, read through
> > > Documentation/pinctrl.txt and come back with a thoroughly rewritten
> > > driver in drivers/pinctrl/pinctrl-as3722.c.
> (...)
> > Yes, the appropriate location is pin control for pull up/down etc
> > configuration but with this device, the actual issue is with the way it is
> > require to configure the pull up/down and input/output of the pin. There is
> > no separate bits for pull up/down and direction and it is  clubbed together.
> > The register's bits are defined as:
> >
> > Selects the GPIO mode (I, I/O, Tri, Pulls) (BIT 2:0)
> >    0 : Input
> >    1 : Output (push and pull) VSUP_GPIO
> >    2 : Output/Input (open drain, only NMOS is active)
> >    3 : ADC input (Tristate)
> >    4 : Input with pull-up to VDD_GPIO_lv
> >    5 : Input with pull-down
> >    6 : Output/Input open drain (nmos) with pull-up to VDD_GPIO_lv,
> >    7 : Output (push and pull) VDD_GPIO_lv
> >
> > So I can not actually configure the pull up/down, open drain and direction
> > independently until every thing is known.
> > Direction come from gpio driver but pull up/down and open drain
> > configuration come from the pin control.
> > And this is only the reason to make all configuration in single driver.
> This is nothing special. Create a single combined GPIO and
> pin control driver using the pin control framework and device
> tree bindings.

Ok, I was thinking that we should not call gpiochip_add() from the pin 
control driver in any new driver and that's why I developed gpio driver 
but it seems it is allowed. I saw some of driver in pinctrl are doing 
pin control and gpio functionality in single driver i.e. 
pincntrl-nomadik, pinctrl-samsung, pincntrl-st etc.
So this gpio driver can be moved now to the pincntrl folder and can use 
pincontrol and gpio framework.

I will respin the change.


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