[PATCH RFC 0/3] PowerPC: implement support for GPIO LIB API

[Grant Likely]

On 1/8/08, Anton Vorontsov <avorontsov at ru.mvista.com> wrote:
> Hi all,
>
> Thanks for the previous review and ideas. Here is the RFC for the
> GPIO LIB support.

I like this layout for gpios.  It's concise and compact.  It will work
well for my gpio driver also.

>
> I'm using it like this:
>
>         qe_pio_a: gpio-controller at 1400 {
>                 #gpio-cells = <1>;
>                 compatible = "fsl,qe-pario-bank";

Here's my only comment: Compatible should have "fsl,<chip>-pario-bank"
first.  Be specific for the first value of the compatible property.
You can add generic names after the specific one if you like, but it's
hard to come up with a generic name when you don't know what a
manufacture is going to do with it's marketing names in the future.

>                 reg = <0x1400 0x18>;
>                 gpio-controller;
>         };
>
>         qe_pio_e: gpio-controller at 1460 {
>                 #gpio-cells = <1>;
>                 compatible = "fsl,qe-pario-bank";
>                 reg = <0x1460 0x18>;
>                 gpio-controller;
>         };
>
>         nand-flash at 1,0 {
>                 compatible = "stmicro,NAND512W3A2BN6E", "fsl,upm-nand";
>                 reg = <1 0 1>;
>                 width = <1>;
>                 upm = "A";
>                 upm-addr-offset = <16>;
>                 upm-cmd-offset = <8>;
>                 gpios = <&qe_pio_e 18 &qe_pio_a 9>;
>                 wait-pattern;
>                 wait-write;
>         };

>
> As you can see I've split single "par_io" node into banks, thus
> the benefits:
> - we can handle banks of different width (Jochen Friedrich asked for
>   this, IIRC. Or I've misunderstood ;-).
> - we can handle banks with different paddings (no more #ifdef PPC85xx).
>
> Also, it's possible to specify different gpio-controllers in the
> gpios = <> property. gpio-specifier is controller specific.
>
>
> The remaining question is about gpio.c placement. prom_parse.c doesn't
> feel as the appropriate place anymore. I think of:
>
> - drivers/gpio/of_gpio.c (driver/gpio/ is in -mm tree);
> - drivers/of/gpio.c
> - keep it in arch/powerpc/kernel/ (though, there is nothing
>   much PowerPC specific).
>
>
> So, to try these patches you'll need apply these from the -mm tree:
> generic-gpio-gpio_chip-support.patch
> generic-gpio-gpio_chip-support-fix.patch
> generic-gpio-gpio_chip-support-gpiolib-locking-simplified.patch
>
> Or just issue this in your working tree:
>
>   git pull git://git.infradead.org/users/cbou/powerpc-gpio.git gpiolib
>
> powerpc-gpio.git's gpiolib branch is galak/powerpc.git master branch +
> -mm patches + these patches.
>
>
> Support for CPM2 is pending.
>
> Thanks!
>
> --
> Anton Vorontsov
> email: cbou at mail.ru
> backup email: ya-cbou at yandex.ru
> irc://irc.freenode.net/bd2
>


-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.