linux-kernel - Re: [RFC PATH 1/2] dt-bindings: gpio: add starfive,jh7100-gpio bindings

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Date:   Fri, 2 Jul 2021 13:56:22 -0700
From:   Drew Fustini <drew@...gleboard.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Michael Zhu <michael.zhu@...rfivetech.com>,
        Fu Wei <tekkamanninja@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Huan Feng <huan.feng@...rfivetech.com>
Subject: Re: [RFC PATH 1/2] dt-bindings: gpio: add starfive,jh7100-gpio
 bindings

On Thu, Jul 01, 2021 at 10:34:56AM +0200, Geert Uytterhoeven wrote:
> Hi Drew,
> 
> On Thu, Jul 1, 2021 at 2:22 AM Drew Fustini <drew@...gleboard.org> wrote:
> > Add bindings for the GPIO controller in the StarFive JH7100 SoC [1].
> >
> > [1] https://github.com/starfive-tech/beaglev_doc
> >
> > Signed-off-by: Drew Fustini <drew@...gleboard.org>
> > Signed-off-by: Huan Feng <huan.feng@...rfivetech.com>
> 
> Thanks for your patch!
> 
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/gpio/starfive,jh7100-gpio.yaml
> > @@ -0,0 +1,60 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/gpio/starfive,jh7100-gpio.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: StarFive JH7100 GPIO controller
> > +
> > +maintainers:
> > +  - Huan Feng <huan.feng@...rfivetech.com>
> > +  - Drew Fustini <drew@...gleboard.org>
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - const: starfive,jh7100-gpio
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    description:
> > +      Interrupt mapping, one per GPIO. Maximum 32 GPIOs.
> > +    minItems: 1
> > +    maxItems: 32
> 
> What about clocks and resets?

Thank you for your feedback, Geert.

GPIO controller uses clk_apb1_bus under dom0_sys.  I believe the device
tree node would use something like this:

  clocks = <&clkgen JH7100_CLK_APB1>;

I see the sifive-gpio.yaml has:

  clocks:
    maxItems: 1

Would that be the correct way to do it for the starfive gpio yaml?


The reset for GPIO controller is presetn under dom_sys.  Do you think
know you know an example that has reset in the YAML?  Is there some code
that would actually make use of that information?

> 
> > +
> > +  gpio-controller: true
> > +
> > +  "#gpio-cells":
> > +    const: 2
> > +
> > +  interrupt-controller: true
> > +
> > +  "#interrupt-cells":
> > +    const: 2
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - interrupts
> > +  - interrupt-controller
> > +  - "#interrupt-cells"
> > +  - "#gpio-cells"
> > +  - gpio-controller

Do you think I should add 'clocks' to 'required:'?

> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +      gpio@...10000 {
> > +        compatible = "starfive,jh7100-gpio";
> > +        reg = <0x11910000 0x10000>;
> > +        gpio-controller;
> > +        #gpio-cells = <2>;
> > +        interrupt-controller;
> > +        #interrupt-cells = <2>;
> > +        interrupts = <32>;

I would add:

  clocks = <&clkgen JH7100_CLK_APB1>;

But I am not sure how reset would work?


Thank you,
Drew