Am Montag, 27. August 2012, 11:51:27 schrieb Vasily Khoruzhick:
> On Mon, Aug 27, 2012 at 12:44 PM, Heiko Stübner <heiko@xxxxxxxxx> wrote:
> > Hi Vasily,
> >
> > I'm not sure I follow :-) .
> >
> > The compatible property here only sets the mechanism on how to handle the
> > gpios defined in the devicetree - here to use the s3c24xx-style. As you
> > can see in gpio-samsung.c the handling is already unified for all the
> > s3c24xx architectures.
> >
> > The definition of what gpio banks exist is then done in the respective
> > devicetree file for the individual SoC. And of course here one would have
> > individual definitions, depending on the banks present.
> >
> > For reference my quite empty s3c2416.dtsi file currently looks like:
> >
> > /include/ "skeleton.dtsi"
> >
> > / {
> >
> > compatible = "samsung,s3c2416";
> >
> > cpus {
> >
> > cpu@0 {
> >
> > compatible = "arm,arm926ejs";
> >
> > };
> >
> > };
> >
> > gpio-controllers {
> >
> > #address-cells = <1>;
> > #size-cells = <1>;
> > gpio-controller;
> > ranges;
> >
> > gpa: gpio-controller@56000000 {
> >
> > compatible = "samsung,s3c24xx-gpio";
> > reg = <0x56000000 0x10>;
> > #gpio-cells = <3>;
> >
> > };
> >
> > gpb: gpio-controller@56000010 {
> >
> > compatible = "samsung,s3c24xx-gpio";
> > reg = <0x56000010 0x10>;
> > #gpio-cells = <3>;
> >
> > };
[ ... ]
> > };
> >
> > };
> >
> > Other s3c24xx SoCs would of course need to define their own.
>
> I see. But how does it handle GPA bank (which is output-only, and
> GPACON differs a bit from GP{B-J}CON? And some banks has lower number
> (not 16) of GPIOs, like GPH.
>
> Also, what would be value for S3C_GPIO_END?
The creation of the banks is still done in gpio-samsung.c and the special
handling of bank-a is still sitting in the s3c24xx_gpios[] array there.
In general the gpios are still created completely like before and the
devicetree information is only attached to them so that dt-devices can
reference them.
As you can see in the original patch, after the respective chip got created in
s3c24xx_gpiolib_add_chips, s3c24xx_gpiolib_attach_ofnode searches for the
representation of it in the device tree and attaches this to the chip.
So nothing really changed, except that dt-devices can now reference gpios and
if they do s3c24xx_gpio_xlate will get called to configure them with the
target values from the dt.
Currently I'm also only using it in a mixed mode configuration [1],
supplementing a normal machine file with some devices from the devicetree -
especially as I still need to figure out, what to do about the interrupt
controller.
Heiko
[1] https://github.com/mmind/linux-es600/blob/topic/es600-
devel/arch/arm/boot/dts/s3c24xx-sg06.dts
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