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Date:   Fri, 6 Oct 2023 08:23:46 -0500
From:   Rob Herring <robh@kernel.org>
To:     AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc:     sudeep.holla@arm.com, cristian.marussi@arm.com,
        krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
        linus.walleij@linaro.org, Oleksii_Moisieiev@epam.com,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org
Subject: Re: [RFC v2 5/5] dt-bindings: gpio: Add bindings for pinctrl based
 generic gpio driver
Message-ID: <20231006132346.GA3426353-robh@kernel.org>
References: <20231005025843.508689-1-takahiro.akashi@linaro.org>
 <20231005025843.508689-6-takahiro.akashi@linaro.org>
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In-Reply-To: <20231005025843.508689-6-takahiro.akashi@linaro.org>
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On Thu, Oct 05, 2023 at 11:58:43AM +0900, AKASHI Takahiro wrote:
> A dt binding for pin controller based generic gpio driver is defined in
> this commit. One usable device is Arm's SCMI.

You don't need a "generic" binding to have a generic driver. Keep the 
binding specific and then decide in the OS to whether to use a generic 
or specific driver. That decision could change over time, but the 
binding can't. For example, see simple-panel.


> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
> RFC v2 (Oct 5, 2023)
> * rename the binding to pin-control-gpio
> * add the "description"
> * remove nodename, hog properties, and a consumer example
> RFC (Oct 2, 2023)
> ---
>  .../bindings/gpio/pin-control-gpio.yaml       | 55 +++++++++++++++++++
>  1 file changed, 55 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> new file mode 100644
> index 000000000000..bc935dbd7edb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> @@ -0,0 +1,55 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpio/pin-control-gpio.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Pin control based generic GPIO controller
> +
> +description:
> +  The pin control-based GPIO will facilitate a pin controller's ability
> +  to drive electric lines high/low and other generic properties of a
> +  pin controller to perform general-purpose one-bit binary I/O.
> +
> +maintainers:
> +  - AKASHI Takahiro <akashi.takahiro@linaro.org>
> +
> +properties:
> +  compatible:
> +    const: pin-control-gpio
> +
> +  gpio-controller: true
> +
> +  "#gpio-cells":
> +    const: 2
> +
> +  gpio-ranges: true
> +
> +  gpio-ranges-group-names: true
> +
> +patternProperties:
> +  "^.+-hog(-[0-9]+)?$":
> +    type: object
> +
> +    required:
> +      - gpio-hog
> +
> +required:
> +  - compatible
> +  - gpio-controller
> +  - "#gpio-cells"
> +  - gpio-ranges
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    gpio0: gpio@0 {
> +        compatible = "pin-control-gpio";
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +        gpio-ranges = <&scmi_pinctrl 0 10 5>,
> +                      <&scmi_pinctrl 5 0 0>;
> +        gpio-ranges-group-names = "",
> +                                  "pinmux_gpio";
> +    };
> -- 
> 2.34.1
>