[PATCH] PINCTRL: SiRF: add CSR SiRFprimaII GPIO driver depending on pinmux APIs

[Barry Song]

Hi Linus,

2012/5/29 Linus Walleij <linus.walleij at linaro.org>:
> On Tue, May 29, 2012 at 8:20 AM, Barry Song <21cnbao at gmail.com> wrote:
>> 2012/5/29 Linus Walleij <linus.walleij at linaro.org>:
>>> On Mon, May 28, 2012 at 11:03 PM, Barry Song <21cnbao at gmail.com> wrote:
>>>>
>>>> here i splitted into two files just for viewing, and at the same time,
>>>> i remap the same memory twice in pinctrl-sirf.c and gpio-sirf.c. they
>>>> share same memory area.
>>>
>>> Hmmmm.... but do they ever write into the same registers?
>>
>> they share the same IOMEM area, but gpio set registers have different
>> offset with pinmux. is there any difference between writing same
>> registers and writing different registers? mainly, they are from the
>> same hardware controller.
>
> I don't really have an opinion on this, you can do it either way.
>
> It's nice to split the files into separate drivers for smaller files and
> cleanly cut devices.
>
> It's also nice to have it all in one file so you can get the whole picture
> of how the hardware works.

i think i'd better to have one driver for both. if i move to
gpio-generic driver for gpio module, gpio-generic driver will not
request gpio from pinctrl, but i need. and on the other hand,
gpio-generic doesn't include irq_chip, but i need.
so to me, gpio-generic driver is much like just for a single-function
gpio controller not good for a multi-function pinmux/gpio/irq
controller.

>
> Usually the problem has been to cross-reference the GPIO ranges
> from another driver, like adding the struct gpio_chip * to the ranges,
> but it seems you don't have this problem in your driver? If you think
> you will run into this problem, merge it into the pinctrl driver to
> save yourself from lots of trouble.

for the range issue, basically we have a (pinmux pin, gpio, irq) pair,
one pinmux pin can be a gpio pin and an external irq source , so
actually, i need to pinctrl_request_gpio() in my gpio_chip.request().
i would think prima2 pinctrl driver can be much like pinctrl-nomadik.c
and pinctrl-coh901.c, which are all of pinmux, gpio and irq chip.  i
might follow them and improve pinctrl-sirf.c to include gpio/irq too.

>
> Maybe someone else has some ideas?
>
> Yours,
> Linus Walleij

Thanks
barry