linux-kernel - Re: [PATCH 1/2] dt-bindings: hwmon: Add binding for max6639

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Date:   Wed, 5 Oct 2022 18:46:16 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Rob Herring <robh@...nel.org>
Cc:     devicetree@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Roland Stigge <stigge@...com.de>, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        Marcello Sylvester Bauer <sylv@...v.io>
Subject: Re: [PATCH 1/2] dt-bindings: hwmon: Add binding for max6639

Hi Rob,

I can add common fan bindings.
Below are the properties that I can think of:
max-rpm, pulse-per-revolution
Let me know what you think.

Regards,
Naresh Solanki



On Fri, 30 Sept 2022 at 01:02, Rob Herring <robh@...nel.org> wrote:
>
> On Thu, Sep 22, 2022 at 07:07:17AM +0200, Naresh Solanki wrote:
> > From: Marcello Sylvester Bauer <sylv@...v.io>
> >
> > Add Devicetree binding documentation for Maxim MAX6639 temperature
> > monitor with PWM fan-speed controller.
> >
> > Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
> > Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> > ---
> >  .../bindings/hwmon/maxim,max6639.yaml         | 112 ++++++++++++++++++
> >  1 file changed, 112 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml b/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
> > new file mode 100644
> > index 000000000000..c845fb989af2
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml
> > @@ -0,0 +1,112 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +
> > +$id: http://devicetree.org/schemas/hwmon/maxim,max6639.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Maxim max6639
> > +
> > +maintainers:
> > +  - Roland Stigge <stigge@...com.de>
> > +
> > +description: |
> > +  The MAX6639 is a 2-channel temperature monitor with dual, automatic, PWM
> > +  fan-speed controller.  It monitors its own temperature and one external
> > +  diode-connected transistor or the temperatures of two external diode-connected
> > +  transistors, typically available in CPUs, FPGAs, or GPUs.
> > +
> > +  Datasheets:
> > +    https://datasheets.maximintegrated.com/en/ds/MAX6639-MAX6639F.pdf
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - maxim,max6639
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  '#address-cells':
> > +    const: 1
> > +
> > +  '#size-cells':
> > +    const: 0
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - "fan@0"
> > +  - "fan@1"
> > +
> > +additionalProperties: false
> > +
> > +patternProperties:
> > +  "^fan@[0-1]$":
> > +    type: object
> > +    description: |
> > +      Represents the two fans and their specific configuration.
> > +
> > +    properties:
> > +      reg:
> > +        description: |
> > +          The fan number.
>
> Addresses are a property of the parent (the fan controller), not the
> fan.
>
> > +        items:
> > +          minimum: 0
> > +          maximum: 1
> > +
> > +      pwm-polarity:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        enum: [0, 1]
> > +        default: 1
> > +        description:
> > +          PWM output is low at 100% duty cycle when this bit is set to zero. PWM
> > +          output is high at 100% duty cycle when this bit is set to 1.
>
> IIRC, the PWM binding provides for this. The parent should probably be a
> PWM provider.
>
> > +
> > +      pulses-per-revolution:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        enum: [1, 2, 3, 4]
> > +        default: 2
> > +        description:
> > +          Value specifying the number of pulses per revolution of the controlled
> > +          FAN.
> > +
> > +      maxim,rpm-range:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        enum: [2000, 4000, 8000, 16000]
> > +        default: 4000
> > +        description:
> > +          Scales the tachometer counter by setting the maximum (full-scale) value
> > +          of the RPM range for max6639.
>
> Is this a property of the fan? How is this maxim specific?
>
>
> The bigger issue here is we need a common fan binding. I'm not inclined
> to accept any more fan controller bindings with fan properties until we
> do.
>
> Rob