Re: [RFC 4/4] dt-bindings: gpio: Add bindings for SCMI pinctrl based gpio

AKASHI Takahiro
2023-10-03T00:42:07Z

Hi Rob,

On Mon, Oct 02, 2023 at 09:41:55AM -0500, Rob Herring wrote:
> On Mon, Oct 02, 2023 at 11:16:02AM +0900, AKASHI Takahiro wrote:
> > A dt binding for SCMI pinctrl based gpio driver is defined in this
> > commit. It basically conforms to generic pinctrl-gpio mapping framework.
>
> What is "generic pinctrl-gpio mapping framework"? DT doesn't have
> frameworks.

I meant to refer to section 2.1-2.3 in "Documentation/devicetree/bindings/gpio/gpio.txt". The semantics is implemented in drivers/gpio/gpiolib(-of).c.

> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > ---
> > .../bindings/gpio/arm,scmi-gpio.yaml | 71 +++++++++++++++++++
> > 1 file changed, 71 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/gpio/arm,scmi-gpio.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/gpio/arm,scmi-gpio.yaml b/Documentation/devicetree/bindings/gpio/arm,scmi-gpio.yaml
> > new file mode 100644
> > index 000000000000..2601c5594567
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/gpio/arm,scmi-gpio.yaml
> > @@ -0,0 +1,71 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/gpio/arm,scmi-gpio.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: SCMI pinctrl based generic GPIO controller
> > +
> > +maintainers:
> > + - AKASHI Takahiro <akashi.takahiro@linaro.org>
> > +
> > +properties:
> > + $nodename:
> > + pattern: "^scmi_gpio(@[0-9a-f]+)$"
>
> Not the correct name.

How not?

> > +
> > + compatible:
> > + const: arm,scmi-gpio-generic
>
> What makes it generic? No such thing. Just drop '-generic'.

I will discuss this issue in following Cristian's comment.

>
> > +
> > + gpio-controller: true
> > +
> > + "#gpio-cells":
> > + const: 2
> > +
> > + gpio-ranges: true
> > +
> > + gpio-ranges-group-names: true
> > +
> > +patternProperties:
> > + "^.+-hog(-[0-9]+)?$":
> > + type: object
> > + properties:
> > + gpio-hog: true
> > + gpios: true
> > + input: true
> > + output-high: true
> > + output-low: true
> > + line-name: true
> > +
> > + required:
> > + - gpio-hog
> > + - gpios
>
> You don't need all this just 'required: [ gpio-hog ]'. Then the hog
> schema will check the rest.

Okay.

> > +
> > + additionalProperties: false
> > +
> > +required:
> > + - compatible
> > + - gpio-controller
> > + - "#gpio-cells"
> > + - gpio-ranges
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + #include <dt-bindings/gpio/gpio.h>
> > +
> > + scmi_gpio_0: scmi_gpio@0 {
>
> gpio {
>
> But doesn't SCMI have protocol numbers?
>
> > + compatible = "arm,scmi-gpio";
> > + gpio-controller;
> > + #gpio-cells = <2>;
> > + gpio-ranges = <&scmi_pinctrl 0 10 5>,
> > + <&scmi_pinctrl 5 0 0>;
> > + gpio-ranges-group-names = "",
> > + "pinmux_gpio";
> > + };
> > +
> > + // Consumer:
>
> Outside the scope of this binding. Drop this node.

Even though it's in an example?
"#gpio-cells" has a meaning in consumer side.

-Takahiro Akashi

> > + sdhci0_pwrseq {
> > + compatible = "mmc-pwrseq-emmc";
> > + reset-gpios = <&scmi_gpio_0 0 GPIO_ACTIVE_LOW>;
> > + };
> > --
> > 2.34.1
> >