Re: [PATCH v2 1/6] dt-bindings: hwmon: add Microchip LAN969x fan controller

[Conor Dooley]

On Mon, Nov 09, 2026 at 02:35:05PM +0100, Robert Marko wrote:
> The LAN969x fan controller has a PWM output and tachometer input in a
> register block separate from the Sparx5-compatible temperature sensor.
> Describe it with its own compatible and binding.
> 
> The optional fan child specifies PWM period and polarity, tachometer
> pulses per revolution, and thermal cooling levels.
> 
> Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
> ---
> Changes in v2:
> - Describe the fan controller in a separate binding and compatible.
> - Keep the existing temperature-sensor binding unchanged.

So, I think that this device has been modelled incorrectly from the
outset. "devcpu_gcb" should probably be a syscon/simplemfd, as least
going off of what I see in
https://microchip-ung.github.io/lan969x-automotive_reginfo/reginfo_LAN969x-Automotive.html?select=devcpu_gcb
and the fact that we see silly offsets in the dts:
		reset: reset-controller@e201000c {
			reg = <0xe201000c 0x4>;
		};

		gpio: pinctrl@e20100d4 {
			reg = <0xe20100d4 0xd4>,
			      <0xe2010370 0xa8>;
		};

		mdio0: mdio@e20101a8 {
			reg = <0xe20101a8 0x24>;
		};

		mdio1: mdio@e20101cc {
			reg = <0xe20101cc 0x24>;
		};

		sgpio: gpio@e2010230 {
			reg = <0xe2010230 0x118>;
		};
That ship has sailed I think though, so I'm not going to ask you to
rework this whole device.

> 
>  .../bindings/hwmon/microchip,lan9691-fan.yaml | 83 +++++++++++++++++++
>  1 file changed, 83 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,lan9691-fan.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/microchip,lan9691-fan.yaml b/Documentation/devicetree/bindings/hwmon/microchip,lan9691-fan.yaml
> new file mode 100644
> index 0000000000000..0b7d38a6d20ae
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/microchip,lan9691-fan.yaml
> @@ -0,0 +1,83 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwmon/microchip,lan9691-fan.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microchip LAN969x Fan Controller
> +
> +maintainers:
> +  - Robert Marko <robert.marko@xxxxxxxxxx>
> +
> +description: |
> +  LAN969x fan controller with a PWM output and tachometer input. The fan
> +  child's pwms property references this node to specify the PWM period and
> +  polarity.
> +
> +properties:
> +  compatible:
> +    const: microchip,lan9691-fan
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    items:
> +      - description: System reference clock
> +
> +  '#pwm-cells':
> +    const: 2
> +    description: |
> +      Number of cells in a PWM specifier.
> +      - cell 0: PWM period in nanoseconds
> +      - cell 1: PWM polarity: 0 or PWM_POLARITY_INVERTED
> +
> +  fan:
> +    $ref: fan-common.yaml#
> +    unevaluatedProperties: false
> +
> +    properties:
> +      cooling-levels:
> +        description:
> +          PWM duty-cycle values corresponding to thermal cooling states.
> +        items:
> +          maximum: 255
> +
> +      pulses-per-revolution:
> +        minimum: 1
> +        maximum: 4
> +        default: 2
> +
> +    required:
> +      - pwms
> +
> +    dependencies:
> +      '#cooling-cells':
> +        - cooling-levels
> +      cooling-levels:
> +        - '#cooling-cells'
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - '#pwm-cells'
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/pwm/pwm.h>
> +
> +    fanctrl: fan-controller@e2010348 {
> +        compatible = "microchip,lan9691-fan";
> +        reg = <0xe2010348 0xc>;

btw, how do I translate the addresses you have here to those in
https://microchip-ung.github.io/lan969x-automotive_reginfo/reginfo_LAN969x-Automotive.html?select=devcpu_gcb,fan_ctrl
? Or are you looking at a register map in a different form?

Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
pw-bot: not-applicable

Cheers,
Conor.

> +        clocks = <&sys_clk>;
> +        #pwm-cells = <2>;
> +
> +        fan {
> +            pwms = <&fanctrl 40000 PWM_POLARITY_INVERTED>;
> +            cooling-levels = <0 128 192 255>;
> +            #cooling-cells = <2>;
> +        };
> +    };
> -- 
> 2.56.0
>

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