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

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Date:	Tue, 6 May 2014 10:01:11 -0500
From:	Alan Tull <delicious.quinoa@...il.com>
To:	Olof Johansson <olof@...om.net>
Cc:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Alan Tull <atull@...era.com>,
	LinusW <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dinh Nguyen <dinguyen@...era.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/7] ARM: dts: socfpga: add gpio pieces

On Mon, May 5, 2014 at 5:02 PM, Olof Johansson <olof@...om.net> wrote:
> 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@...utronix.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@...r.kernel.org
>> Acked-by: Alan Tull <atull@...era.com>
>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.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@...08000 {
>> +                       #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@...08000 {
>                        #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

The synopsys gpio ip can have 1, 2, or 3 gpio ports of varying widths
per IP block.  The simpler bindings assume one gpio port per IP block.

Alan Tull
aka
delicious quinoa
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