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

From: Drew Fustini <drew@beagleboard.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Rob Herring <robh+dt@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Michael Zhu <michael.zhu@starfivetech.com>,
	Fu Wei <tekkamanninja@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Huan Feng <huan.feng@starfivetech.com>
Subject: Re: [RFC PATH 1/2] dt-bindings: gpio: add starfive,jh7100-gpio bindings
Date: Fri, 2 Jul 2021 13:56:22 -0700	[thread overview]
Message-ID: <20210702205622.GA1035183@x1> (raw)
In-Reply-To: <CAMuHMdWLNy6_CnFEYDvHSEdMYH=T_Fy=DCjZCF9kPGWcD-B0Qw@mail.gmail.com>

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@beagleboard.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@beagleboard.org>
> > Signed-off-by: Huan Feng <huan.feng@starfivetech.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@starfivetech.com>
> > +  - Drew Fustini <drew@beagleboard.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@11910000 {
> > +        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