Re: [PATCH 1/7] ARM: dts: socfpga: add gpio pieces

[Olof Johansson <olof@lixom.net>]

Hi,

I saw this patch as it came in through Dinh's pull request, see below:


On Sat, Mar 22, 2014 at 9:16 AM, Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
> The cycloneV has three gpio controllers, the first two with 29 gpios, the last
> one with 27. This patch adds the three controller with the gpio driver which is
> now sitting the gpio tree.
>
> Cc: devicetree@vger.kernel.org
> Acked-by: Alan Tull <atull@altera.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> v1…v2:
>         - #gpio-cells = <2>
>         - third gpio block has now only 27 gpios
>
>  arch/arm/boot/dts/socfpga.dtsi | 64 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
>
> diff --git a/arch/arm/boot/dts/socfpga.dtsi b/arch/arm/boot/dts/socfpga.dtsi
> index 537f1a5..2a84e67 100644
> --- a/arch/arm/boot/dts/socfpga.dtsi
> +++ b/arch/arm/boot/dts/socfpga.dtsi
> @@ -463,6 +463,70 @@
>                         status = "disabled";
>                 };
>
> +               gpio@ff708000 {
> +                       #address-cells = <1>;
> +                       #size-cells = <0>;
> +                       compatible = "snps,dw-apb-gpio";
> +                       reg = <0xff708000 0x1000>;
> +                       clocks = <&per_base_clk>;
> +                       status = "disabled";
> +
> +                       gpio0: gpio-controller@0 {
> +                               compatible = "snps,dw-apb-gpio-port";
> +                               gpio-controller;
> +                               #gpio-cells = <2>;
> +                               snps,nr-gpios = <29>;
> +                               reg = <0>;
> +                               interrupt-controller;
> +                               #interrupt-cells = <2>;
> +                               interrupts = <0 164 4>;
> +                       };
> +               };

This is an odd setup. We usually would have it all in one node, since
the @ff708000 is the GPIO controller, instead of adding a subnode with
the actual GPIO info.

So I would have expected something more like:


gpio0: gpio-controller@ff708000 {
                       #address-cells = <1>;
                       #size-cells = <0>;
                       compatible = "snps,dw-apb-gpio";
                       reg = <0xff708000 0x1000>;
                       interrupts = <0 164 4>;
                      clocks = <&per_base_clk>;
                       status = "disabled";
                       gpio-controller;
                       #gpio-cells = <2>;
                       snps,nr-gpios = <29>;
                       interrupt-controller;
                       #interrupt-cells = <2>;
               };


... or is there some underlying reason for having the two-layer
approach that isn't obvious from this device tree?


-Olof