Re: [PATCH v6 4/8] dt-bindings: mfd: Binding for RTL8231

[Rob Herring <robh@kernel.org>]

On Tue, Oct 21, 2025 at 04:23:59PM +0200, Sander Vanheule wrote:
> Add a binding description for the Realtek RTL8231, a GPIO and LED
> expander chip commonly used in ethernet switches based on a Realtek
> switch SoC. These chips can be addressed via an MDIO or SMI bus, or used
> as a plain 36-bit shift register.
> 
> This binding only describes the feature set provided by the MDIO/SMI
> configuration, and covers the GPIO, PWM, and pin control properties. The
> LED properties are defined in a separate binding.
> 
> Signed-off-by: Sander Vanheule <sander@svanheule.net>
> ---
>  .../bindings/mfd/realtek,rtl8231.yaml         | 189 ++++++++++++++++++
>  1 file changed, 189 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/realtek,rtl8231.yaml
> 
> diff --git a/Documentation/devicetree/bindings/mfd/realtek,rtl8231.yaml b/Documentation/devicetree/bindings/mfd/realtek,rtl8231.yaml
> new file mode 100644
> index 000000000000..25135917d3f2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/realtek,rtl8231.yaml
> @@ -0,0 +1,189 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mfd/realtek,rtl8231.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Realtek RTL8231 GPIO and LED expander.
> +
> +maintainers:
> +  - Sander Vanheule <sander@svanheule.net>
> +
> +description: |
> +  The RTL8231 is a GPIO and LED expander chip, providing up to 37 GPIOs, up to
> +  88 LEDs, and up to one PWM output. This device is frequently used alongside
> +  Realtek switch SoCs, to provide additional I/O capabilities.
> +
> +  To manage the RTL8231's features, its strapping pins can be used to configure
> +  it in one of three modes: shift register, MDIO device, or SMI device. The
> +  shift register mode does not need special support. In MDIO or SMI mode, most
> +  pins can be configured as a GPIO output or LED matrix scan line/column. One
> +  pin can be used as PWM output.
> +
> +  The GPIO, PWM, and pin control are part of the main node. LED support is
> +  configured as a sub-node.
> +
> +properties:
> +  compatible:
> +    const: realtek,rtl8231
> +
> +  reg:
> +    description: MDIO or SMI device address.
> +    maxItems: 1
> +
> +  # GPIO support
> +  gpio-controller: true
> +
> +  "#gpio-cells":
> +    const: 2
> +    description: |

Drop '|' here and elsewhere with no formatting.

> +      The first cell is the pin number and the second cell is used to specify
> +      the GPIO active state.
> +
> +  gpio-ranges:
> +    description: |
> +      Must reference itself, and provide a zero-based mapping for 37 pins.
> +    maxItems: 1
> +
> +  # Pin muxing and configuration
> +  drive-strength:
> +    description: |
> +      Common drive strength used for all GPIO output pins, must be 4mA or 8mA.
> +      On reset, this value will default to 8mA.
> +    enum: [4, 8]
> +
> +  # LED scanning matrix
> +  led-controller:
> +    $ref: ../leds/realtek,rtl8231-leds.yaml#
> +
> +  # PWM output
> +  "#pwm-cells":
> +    description: |
> +      Twos cells with PWM index (must be 0) and PWM frequency in Hz. To use
> +      the PWM output, gpio35 must be muxed to its 'pwm' function. Valid
> +      frequency values for consumers are 1200, 1600, 2000, 2400, 2800, 3200,
> +      4000, and 4800.
> +    const: 2
> +
> +patternProperties:
> +  "-pins$":
> +    type: object
> +    $ref: ../pinctrl/pinmux-node.yaml#
> +
> +    properties:
> +      pins:
> +        items:
> +          enum: [gpio0, gpio1, gpio2, gpio3, gpio4, gpio5, gpio6, gpio7,
> +                 gpio8, gpio9, gpio10, gpio11, gpio12, gpio13, gpio14, gpio15,
> +                 gpio16, gpio17, gpio18, gpio19, gpio20, gpio21, gpio22, gpio23,
> +                 gpio24, gpio25, gpio26, gpio27, gpio28, gpio29, gpio30, gpio31,
> +                 gpio32, gpio33, gpio34, gpio35, gpio36]
> +        minItems: 1
> +        maxItems: 37

blank line

Other than those nits, looks good.

Rob