linux-kernel - Re: [PATCH v3 4/4] dt-bindings: iio: adc: ad7949: add per channel reference

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Message-ID: <20210715163350.GA1196436@robh.at.kernel.org>
Date:   Thu, 15 Jul 2021 10:33:50 -0600
From:   Rob Herring <robh@...nel.org>
To:     Liam Beguin <liambeguin@...il.com>
Cc:     lars@...afoo.de, Michael.Hennerich@...log.com, jic23@...nel.org,
        charles-antoine.couret@...ensium.com, Nuno.Sa@...log.com,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 4/4] dt-bindings: iio: adc: ad7949: add per channel
 reference

On Tue, Jul 13, 2021 at 12:34:25AM -0400, Liam Beguin wrote:
> From: Liam Beguin <lvb@...hos.com>
> 
> Add bindings documentation describing per channel reference voltage
> selection.
> This adds the adi,internal-ref-mv property, and child nodes for each
> channel. This is required to properly configure the ADC sample request
> based on which reference source should be used for the calculation.
> 
> Signed-off-by: Liam Beguin <lvb@...hos.com>
> ---
>  .../bindings/iio/adc/adi,ad7949.yaml          | 71 +++++++++++++++++--
>  1 file changed, 67 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7949.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7949.yaml
> index 9b56bd4d5510..18abba3b0b4d 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7949.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7949.yaml
> @@ -26,19 +26,65 @@ properties:
>    reg:
>      maxItems: 1
>  
> +  vrefin-supply:
> +    description:
> +      Buffered ADC reference voltage supply.
> +
>    vref-supply:
>      description:
> -      ADC reference voltage supply
> +      Unbuffered ADC reference voltage supply.
>  
>    spi-max-frequency: true
>  
> -  "#io-channel-cells":
> +  '#io-channel-cells':
>      const: 1
>  
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +

extra blank line.

>  required:
>    - compatible
>    - reg
> -  - vref-supply
> +
> +patternProperties:
> +  '^channel@([0-7])$':
> +    type: object
> +    description: |
> +      Represents the external channels which are connected to the ADC.
> +
> +    properties:
> +      reg:
> +        description: |
> +          The channel number.
> +          Up to 4 channels, numbered from 0 to 3 for adi,ad7682.
> +          Up to 8 channels, numbered from 0 to 7 for adi,ad7689 and adi,ad7949.
> +        items:
> +          minimum: 0
> +          maximum: 7
> +
> +      adi,internal-ref-mv:

Use standard unit suffix name. Then you can drop the type $ref.

> +        description: |
> +          Internal reference voltage selection in millivolts.
> +
> +          If no internal reference is specified, the channel will default to the
> +          external reference defined by vrefin-supply (or vref-supply).
> +          vrefin-supply will take precedence over vref-supply if both are defined.
> +
> +          If no supplies are defined, the reference selection will default to
> +          4096mV internal reference.
> +
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        enum: [2500, 4096]
> +        default: 4096
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false
>  
>  additionalProperties: false
>  
> @@ -49,9 +95,26 @@ examples:
>          #size-cells = <0>;
>  
>          adc@0 {
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
>              compatible = "adi,ad7949";
>              reg = <0>;
> -            vref-supply = <&vdd_supply>;
> +            vrefin-supply = <&vdd_supply>;
> +
> +            channel@0 {
> +                adi,internal-ref-mv = <4096>;
> +                reg = <0>;
> +            };
> +
> +            channel@1 {
> +                adi,internal-ref-mv = <2500>;
> +                reg = <1>;
> +            };
> +
> +            channel@2 {
> +                reg = <2>;
> +            };
>          };
>      };
>  ...
> -- 
> 2.30.1.489.g328c10930387
> 
>