Re: [PATCH v8 3/6] dt-bindings: pwm: airoha: Add EN7581 pwm

[Rob Herring <robh@kernel.org>]

On Fri, Oct 18, 2024 at 03:19:04PM +0200, Lorenzo Bianconi wrote:
> Introduce device-tree binding documentation for Airoha EN7581 pwm
> controller.
> 
> Co-developed-by: Christian Marangi <ansuelsmth@gmail.com>
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  .../devicetree/bindings/pwm/airoha,en7581-pwm.yaml | 61 ++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/airoha,en7581-pwm.yaml b/Documentation/devicetree/bindings/pwm/airoha,en7581-pwm.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..fb68c10b037b840a571a2ceee57f13cbae78da66
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/airoha,en7581-pwm.yaml
> @@ -0,0 +1,61 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pwm/airoha,en7581-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Airoha EN7581 PWM Controller
> +
> +maintainers:
> +  - Lorenzo Bianconi <lorenzo@kernel.org>
> +
> +allOf:
> +  - $ref: pwm.yaml#
> +
> +properties:
> +  compatible:
> +    const: airoha,en7581-pwm
> +
> +  "#pwm-cells":
> +    const: 3
> +
> +  airoha,74hc595-mode:
> +    description: Set the PWM to handle attached shift register chip 74HC595.
> +
> +      With this disabled, PWM assume a 74HC164 chip attached.
> +
> +      The main difference between the 2 chip is the presence of a latch pin
> +      that needs to triggered to apply the configuration and PWM needs to
> +      account for that.
> +    type: boolean
> +
> +  airoha,sipo-clock-divisor:
> +    description: Declare Shift Register chip clock divisor (clock source is
> +      from SoC APB Clock)

Where is the clock source defined?

You can specify the PWM frequency in PWM cells and should be able to get 
the APB Clock frequency. Then you can calculate the divider.

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 32
> +    enum: [4, 8, 16, 32]
> +
> +  airoha,sipo-clock-delay:
> +    description: Declare Serial GPIO Clock delay.
> +      This can be needed to permit the attached shift register to correctly
> +      setup and apply settings. Value must NOT be greater than
> +      "airoha,sipo-clock-divisor" / 2
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 1
> +    minimum: 1
> +    maximum: 16
> +
> +required:
> +  - compatible
> +  - "#pwm-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    pwm {
> +      compatible = "airoha,en7581-pwm";
> +
> +      #pwm-cells = <3>;
> +    };
> 
> -- 
> 2.47.0
>