Re: [PATCH v6 1/2] dt-bindings: gpio: add gpio-line-mux controller

[Rob Herring <robh@kernel.org>]

On Tue, Nov 11, 2025 at 09:27:03AM +0000, Jonas Jelonek wrote:
> Add dt-schema for a gpio-line-mux controller which exposes virtual
> GPIOs for a shared GPIO controlled by a multiplexer, e.g. a gpio-mux.
> 
> The gpio-line-mux controller is a gpio-controller, thus has mostly the
> same semantics. However, it requires a mux-control to be specified upon
> which it will operate.
> 
> Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  .../bindings/gpio/gpio-line-mux.yaml          | 109 ++++++++++++++++++
>  1 file changed, 109 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml b/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml
> new file mode 100644
> index 000000000000..0228e9915b92
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/gpio-line-mux.yaml
> @@ -0,0 +1,109 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpio/gpio-line-mux.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: GPIO line mux
> +
> +maintainers:
> +  - Jonas Jelonek <jelonek.jonas@gmail.com>
> +
> +description: |
> +  A GPIO controller to provide virtual GPIOs for a 1-to-many input-only mapping
> +  backed by a single shared GPIO and a multiplexer. A simple illustrated
> +  example is

colon on the end.

> +
> +            +----- A
> +    IN     /
> +    <-----o------- B
> +        / |\
> +        | | +----- C
> +        | |  \
> +        | |   +--- D
> +        | |
> +       M1 M0
> +
> +    MUX CONTROL
> +
> +     M1 M0   IN
> +      0  0   A
> +      0  1   B
> +      1  0   C
> +      1  1   D
> +
> +  This can be used in case a real GPIO is connected to multiple inputs and
> +  controlled by a multiplexer, and another subsystem/driver does not work
> +  directly with the multiplexer subsystem.
> +
> +properties:
> +  compatible:
> +    const: gpio-line-mux
> +
> +  gpio-controller: true
> +
> +  "#gpio-cells":
> +    const: 2
> +
> +  gpio-line-mux-states:
> +    description: Mux states corresponding to the virtual GPIOs.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +
> +  gpio-line-names: true
> +
> +  mux-controls:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array

Already has a type. Drop the ref.

> +    maxItems: 1
> +    description:
> +      Phandle to the multiplexer to control access to the GPIOs.
> +
> +  ngpios: false

No need for this.

> +
> +  muxed-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO which is the '1' in 1-to-many and is shared by the virtual GPIOs
> +      and controlled via the mux.
> +
> +required:
> +  - compatible
> +  - gpio-controller
> +  - gpio-line-mux-states
> +  - mux-controls
> +  - muxed-gpios
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/mux/mux.h>
> +
> +    sfp_gpio_mux: mux-controller-1 {
> +        compatible = "gpio-mux";
> +        mux-gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>,
> +                    <&gpio0 1 GPIO_ACTIVE_HIGH>;
> +        #mux-control-cells = <0>;
> +        idle-state = <MUX_IDLE_AS_IS>;
> +    };
> +
> +    sfp1_gpio: sfp-gpio-1 {
> +        compatible = "gpio-line-mux";
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +
> +        mux-controls = <&sfp_gpio_mux>;
> +        muxed-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
> +
> +        gpio-line-names = "SFP1_LOS", "SFP1_MOD_ABS", "SFP1_TX_FAULT";
> +        gpio-line-mux-states = <0>, <1>, <3>;

gpio-line-names is defined to have an entry for all lines. So 
gpio-line-mux-states is not necessary. You can just do:

gpio-line-names = "SFP1_LOS", "SFP1_MOD_ABS", "", "SFP1_TX_FAULT";

Rob