Re: [PATCH v4 7/8] dt-bindings: iio: adc: add docs for AD7606C-{16,18} parts

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On Fri, Sep 6, 2024 at 12:54 AM David Lechner <dlechner@xxxxxxxxxxxx> wrote:
>
> On 9/5/24 3:24 AM, Alexandru Ardelean wrote:
> > The driver will support the AD7606C-16 and AD7606C-18.
> > This change adds the compatible strings for these devices.
> >
> > The AD7606C-16,18 channels also support these (individually configurable)
> > types of channels:
> >  - bipolar single-ended
> >  - unipolar single-ended
> >  - bipolar differential
> >
> > Signed-off-by: Alexandru Ardelean <aardelean@xxxxxxxxxxxx>
> > ---
> >  .../bindings/iio/adc/adi,ad7606.yaml          | 109 ++++++++++++++++++
> >  1 file changed, 109 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
> > index 69408cae3db9..57537ab0ec82 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
> > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
> > @@ -14,6 +14,8 @@ description: |
> >    https://www.analog.com/media/en/technical-documentation/data-sheets/AD7605-4.pdf
> >    https://www.analog.com/media/en/technical-documentation/data-sheets/ad7606_7606-6_7606-4.pdf
> >    https://www.analog.com/media/en/technical-documentation/data-sheets/AD7606B.pdf
> > +  https://www.analog.com/media/en/technical-documentation/data-sheets/ad7606c-16.pdf
> > +  https://www.analog.com/media/en/technical-documentation/data-sheets/ad7606c-18.pdf
> >    https://www.analog.com/media/en/technical-documentation/data-sheets/AD7616.pdf
> >
> >  properties:
> > @@ -24,11 +26,19 @@ properties:
> >        - adi,ad7606-6
> >        - adi,ad7606-8  # Referred to as AD7606 (without -8) in the datasheet
> >        - adi,ad7606b
> > +      - adi,ad7606c-16
> > +      - adi,ad7606c-18
> >        - adi,ad7616
> >
> >    reg:
> >      maxItems: 1
> >
> > +  "#address-cells":
> > +    const: 1
> > +
> > +  "#size-cells":
> > +    const: 0
> > +
> >    spi-cpha: true
> >
> >    spi-cpol: true
> > @@ -114,6 +124,46 @@ properties:
> >        assumed that the pins are hardwired to VDD.
> >      type: boolean
> >
> > +patternProperties:
> > +  "^channel@[1-8]$":
> > +    type: object
> > +    $ref: adc.yaml
> > +    unevaluatedProperties: false
> > +
> > +    properties:
> > +      reg:
> > +        description:
> > +          The channel number, as specified in the datasheet (from 1 to 8).
> > +        minimum: 1
> > +        maximum: 8
> > +
> > +      diff-channels:
> > +        description:
> > +          Each channel can be configured as a differential bipolar channel.
> > +          The ADC uses the same positive and negative inputs for this.
> > +          This property must be specified as 'reg' (or the channel number) for
> > +          both positive and negative inputs (i.e. diff-channels = <reg reg>).
> > +        items:
> > +          minimum: 1
> > +          maximum: 8
> > +
> > +      bipolar:
> > +        description:
> > +          Each channel can be configured as a unipolar or bipolar single-ended.
> > +          When this property is not specified, it's unipolar, so the ADC will
> > +          have only the positive input wired.
> > +          For this ADC the 'diff-channels' & 'bipolar' properties are mutually
> > +          exclusive.
> > +
> > +    required:
> > +      - reg
> > +
> > +    oneOf:
> > +      - required:
> > +          - diff-channels
> > +      - required:
> > +          - bipolar
>
> The datasheet (ad7606c-18.pdf) lists the following combinations:
>
> * Bipolar single-ended
> * Unipolar single-ended
> * Bipolar differential
>
> The logic in the oneOf: doesn't match this.
>
> This I think this would be sufficient:
>
> - if:
>     required: [diff-channels]
>   then:
>     required: [bipolar]

So here, I am a bit vague.
This makes 'bipolar' mandatory if 'diff-channels' is mandatory, right?
But then 'bipolar' (on its own) becomes optional?
The way I understood the oneOf case is that:
1. if it's 'diff-channels' then it's specified 'bipolar differential'.
2. if it's 'bipolar' then it's specified as 'bipolar single-ended'
3. otherwise it's unipolar
4. oneOf enforces that at least 'diff-channels' or 'bipolar' is
specified if there is a channel node


>
> > +
> >  required:
> >    - compatible
> >    - reg
> > @@ -170,6 +220,17 @@ allOf:
> >          adi,conversion-start-gpios:
> >            maxItems: 1
> >
> > +  - if:
> > +      not:
> > +        properties:
> > +          compatible:
> > +            enum:
> > +              - adi,ad7606c-16
> > +              - adi,ad7606c-18
> > +    then:
> > +      patternProperties:
> > +        "^channel@[1-8]$": false
> > +
> >  unevaluatedProperties: false
> >
> >  examples:
> > @@ -202,4 +263,52 @@ examples:
> >              standby-gpios = <&gpio 24 GPIO_ACTIVE_LOW>;
> >          };
> >      };
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        adc@0 {
> > +            compatible = "adi,ad7606c-18";
> > +            reg = <0>;
> > +
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            spi-max-frequency = <1000000>;
> > +            spi-cpol;
> > +            spi-cpha;
> > +
> > +            avcc-supply = <&adc_vref>;
> > +            vdrive-supply = <&vdd_supply>;
> > +
> > +            interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
> > +            interrupt-parent = <&gpio>;
> > +
> > +            adi,conversion-start-gpios = <&gpio 17 GPIO_ACTIVE_HIGH>;
> > +            reset-gpios = <&gpio 27 GPIO_ACTIVE_HIGH>;
> > +            adi,first-data-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>;
> > +            standby-gpios = <&gpio 24 GPIO_ACTIVE_LOW>;
> > +
> > +            adi,sw-mode;
> > +
> > +            channel@1 {
> > +                reg = <1>;
> > +                diff-channels = <1 1>;
>
>                    bipolar;
>
> > +            };
> > +
> > +            channel@3 {
> > +                reg = <3>;
> > +                bipolar;
> > +            };
> > +
> > +            channel@8 {
> > +                reg = <8>;
> > +                diff-channels = <8 8>;
>
>                    bipolar;
>
> > +            };
> > +
> > +        };
> > +    };
> >  ...
>





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