Re: [PATCH v2 1/9] dt-bindings: thermal: qcom: add adc-thermal monitor bindings

[Jonathan Cameron <jic23@kernel.org>]

On Thu,  3 Sep 2020 16:21:01 +0300
Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:

> Add bindings for thermal monitor, part of Qualcomm PMIC5 chips. It is a
> close counterpart of VADC part of those PMICs.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  .../bindings/thermal/qcom-spmi-adc-tm5.yaml   | 142 ++++++++++++++++++
>  1 file changed, 142 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/thermal/qcom-spmi-adc-tm5.yaml
> 
> diff --git a/Documentation/devicetree/bindings/thermal/qcom-spmi-adc-tm5.yaml b/Documentation/devicetree/bindings/thermal/qcom-spmi-adc-tm5.yaml
> new file mode 100644
> index 000000000000..94aaf3720b9f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/qcom-spmi-adc-tm5.yaml
> @@ -0,0 +1,142 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/thermal/qcom-spmi-adc-tm5.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm's SPMI PMIC ADC-TM
> +maintainers:
> +  - Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> +
> +properties:
> +  compatible:
> +    const: qcom,spmi-adc-tm5
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  "#thermal-sensor-cells":
> +    const: 1
> +    description:
> +      Number of cells required to uniquely identify the thermal sensors. Since
> +      we have multiple sensors this is set to 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +  io-channels:
> +    description:
> +      From common IIO binding. Used to pipe PMIC ADC channel to thermal monitor
> +
> +  io-channel-names:
> +    description:
> +      From common IIO binding. Names each of IIO channels. The name should
> +      be equal to the sensor's subnode name.
> +
> +  qcom,avg-samples:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: Number of samples to be used for measurement.
> +    enum:
> +      - 1
> +      - 2
> +      - 4
> +      - 8
> +      - 16
> +    default: 1
> +
> +  qcom,decimation:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: This parameter is used to decrease ADC sampling rate.

Just curious, but how is it used?  What do 250, 420 etc actually refer to?

> +    enum:
> +      - 250
> +      - 420
> +      - 840
> +    default: 840
> +
> +patternProperties:
> +  "^([-a-z0-9]*)@[0-9]+$":
> +    type: object
> +    description:
> +      Represent one thermal sensor.
> +
> +    properties:
> +      reg:
> +        description: Specify the sensor channel.
> +        maxItems: 1
> +
> +      qcom,adc-channel:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Corresponding ADC channel ID.

Comment down at the example.

> +
> +      qcom,ratiometric:
> +        $ref: /schemas/types.yaml#/definitions/flag
> +        description:
> +          Channel calibration type.
> +          If this property is specified VADC will use the VDD reference
> +          (1.875V) and GND for channel calibration. If property is not found,
> +          channel will be calibrated with 0V and 1.25V reference channels,
> +          also known as absolute calibration.
> +
> +      qcom,hw-settle-time:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Time between AMUX getting configured and the ADC starting conversion.
> +
> +      qcom,pre-scaling:
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        description: Used for scaling the channel input signal before the signal is fed to VADC. See qcom,spi-vadc specification for the list of possible values.

Very long line.

> +        minItems: 2
> +        maxItems: 2
> +
> +    required:
> +      - reg
> +      - qcom,adc-channel
> +
> +    additionalProperties:
> +      false
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - "#address-cells"
> +  - "#size-cells"
> +  - "#thermal-sensor-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +        pm8150b_adc: adc@3100 {
> +            compatible = "qcom,spmi-adc5";
> +            /* Other propreties are omitted */
> +            conn-therm@4f {
> +                reg = <ADC5_AMUX_THM3_100K_PU>;
> +                qcom,ratiometric;
> +                qcom,hw-settle-time = <200>;
> +            };
> +        };
> +
> +        pm8150b_adc_tm: adc-tm@3500 {
> +            compatible = "qcom,spmi-adc-tm5";
> +            reg = <0x3500>;
> +            interrupts = <0x2 0x35 0x0 IRQ_TYPE_EDGE_RISING>;
> +            #thermal-sensor-cells = <1>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +            io-channels = <&pm8150b_adc ADC5_AMUX_THM3_100K_PU>;
> +            io-channel-names = "conn-therm";
> +
> +            conn-therm@0 {
> +                reg = <0>;
> +                qcom,adc-channel = <ADC5_AMUX_THM3_100K_PU>;

Would we be better off putting the io-channels entry directly in the child
and lose the indirection? Would make the driver a bit more fiddly perhaps
but give a more elegant binding by dropping one level of indirection
/repetition.

> +                qcom,ratiometric;
> +                qcom,hw-settle-time = <200>;
> +            };
> +        };
> +...