[v2,1/2] Add DT bindings YAML schema for PWM fan controller of LGM SoC

Intel's LGM(Lightning Mountain) SoC contains a PWM fan controller
which is only used to control the fan attached to the system. This
PWM controller does not have any other consumer other than fan.
Add DT bindings documentation for this PWM fan controller.

Signed-off-by: Rahul Tanwar <rahul.tanwar@linux.intel.com>
---
 .../devicetree/bindings/pwm/intel,lgm-pwm.yaml     | 57 ++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml

Hello,

On Thu, Jun 18, 2020 at 08:05:12PM +0800, Rahul Tanwar wrote:
> Intel's LGM(Lightning Mountain) SoC contains a PWM fan controller
> which is only used to control the fan attached to the system. This
> PWM controller does not have any other consumer other than fan.
> Add DT bindings documentation for this PWM fan controller.
> 
> Signed-off-by: Rahul Tanwar <rahul.tanwar@linux.intel.com>
> ---
>  .../devicetree/bindings/pwm/intel,lgm-pwm.yaml     | 57 ++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml
> 
> diff --git a/Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml b/Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml
> new file mode 100644
> index 000000000000..e71cc25e4e6a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml
> @@ -0,0 +1,57 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pwm/intel,lgm-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: LGM SoC PWM fan controller
> +
> +maintainers:
> +  - Rahul Tanwar <rahul.tanwar@intel.com>
> +
> +properties:
> +  compatible:
> +    const: intel,lgm-pwm
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#pwm-cells":
> +    const: 2
> +
> +  clocks:
> +    maxItems: 1
> +
> +  resets:
> +    maxItems: 1
> +
> +  intel,fan-wire:
> +    $ref: '/schemas/types.yaml#/definitions/uint32'
> +    description: Specifies fan mode

The default when unspecified is 2.

> +
> +  intel,tach-plus:
> +    $ref: '/schemas/types.yaml#/definitions/uint32'
> +    description: Specifies fan tach pulse periods

Only used with fan-wire = 4, default = 2.

> +
> +  intel,max-rpm:
> +    $ref: '/schemas/types.yaml#/definitions/uint32'
> +    description: Specifies maximum RPM of fan attached to the system

Ditto.

Consistent with my concern that the fan code should not be part of the
PWM driver I wonder if this representation that mixes fan and PWM is
nice enough to be set in stone.

If we decide to keep it as is I wonder if we should drop #pwm-cells as
the hardware doesn't allow other uses for this PWM (IIUC) and so
referencing this node doesn't make sense.

> +required:
> +  - compatible
> +  - reg
> +  - "#pwm-cells"
> +  - clocks
> +  - resets
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    pwm: pwm@e0d00000 {
> +        compatible = "intel,lgm-pwm";
> +        reg = <0xe0d00000 0x30>;
> +        #pwm-cells = <2>;
> +        clocks = <&cgu0 126>;
> +        resets = <&rcu0 0x30 21>;
> +    };

Best regards
Uwe