Re: [PATCH RFC 1/4] dt-bindings: iio: adc: ad7380: add adaq4370-4 and adaq4380-4 compatible parts

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Le dim. 20 oct. 2024 à 15:21, Jonathan Cameron <jic23@xxxxxxxxxx> a écrit :
>
> On Tue, 15 Oct 2024 11:09:06 +0200
> Julien Stephan <jstephan@xxxxxxxxxxxx> wrote:
>
> > adaq4370-4 (2MSPS) and adaq4380-4 (4MSPS) are quad-channel precision data
> > acquisition signal chain μModule solutions compatible with the ad738x
> > family, with the following differences:
> >
> > - configurable gain in front of each 4 adc
> As per quick review I gave for the driver code, I'm not seeing why
> a configurable gain is a DT thing on an ADC vs something that belongs
> in userspace control.  I may be missing something though.
>
> It exists for the ad4000 because the control isn't via registers
> but via pin straps so we can't control it sensibly from userspace.


Hi Jonathan,
I indeed based my work on ad4000. I think my commit description is
erroneous and confusing.
On the first page of the datasheet
(https://www.analog.com/media/en/technical-documentation/data-sheets/adaq4380-4.pdf)
it's written : Pin selectable Gain/attenuation. So I guess adaq4380-4
and adaq4370-4 are working the same way as the adaq4000 series.
I'll rewrite my commit message. Also, I didn't want to restrict users
to the gain values in the datasheet, because I thought they are just
examples and users can always use additional resistance to change the
gain. Am I correct? Or should I use the datasheet values (as adaq4000
series does) ?

Cheers
Julien

>
> Jonathan
>
> > - internal reference is 3V derived from refin-supply (5V)
> > - additional supplies
> >
> > To configure the gain a new patternProperties is added to describe each
> > channel. It is restricted to adaq devices.
> >
> > Signed-off-by: Julien Stephan <jstephan@xxxxxxxxxxxx>
> > ---
> >  .../devicetree/bindings/iio/adc/adi,ad7380.yaml    | 117 +++++++++++++++++++++
> >  1 file changed, 117 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> > index 74d82721637c..3007d8e39684 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> > @@ -25,6 +25,8 @@ description: |
> >    * https://www.analog.com/en/products/ad7386-4.html
> >    * https://www.analog.com/en/products/ad7387-4.html
> >    * https://www.analog.com/en/products/ad7388-4.html
> > +  * https://www.analog.com/en/products/adaq4370-4.html
> > +  * https://www.analog.com/en/products/adaq4380-4.html
> >
> >
> >  $ref: /schemas/spi/spi-peripheral-props.yaml#
> > @@ -46,6 +48,8 @@ properties:
> >        - adi,ad7386-4
> >        - adi,ad7387-4
> >        - adi,ad7388-4
> > +      - adi,adaq4370-4
> > +      - adi,adaq4380-4
> >
> >    reg:
> >      maxItems: 1
> > @@ -59,6 +63,9 @@ properties:
> >    vlogic-supply: true
> >    refio-supply: true
> >    refin-supply: true
> > +  vs-p-supply: true
> > +  vs-n-supply: true
> > +  ldo-supply: true
> >
> >    aina-supply:
> >      description:
> > @@ -86,12 +93,43 @@ properties:
> >        specify the ALERT interrupt.
> >      maxItems: 1
> >
> > +  '#address-cells':
> > +    const: 1
> > +
> > +  '#size-cells':
> > +    const: 0
> > +
> >  required:
> >    - compatible
> >    - reg
> >    - vcc-supply
> >    - vlogic-supply
> >
> > +patternProperties:
> > +  "^channel@([0-3])$":
> > +    $ref: adc.yaml
> > +    type: object
> > +
> > +    properties:
> > +      reg:
> > +        description:
> > +          The channel number. From 0 to 3 corresponding to channels A,B,C,D
> > +        items:
> > +          minimum: 0
> > +          maximum: 3
> > +
> > +      adi,gain-milli:
> > +        description:
> > +          The hardware gain applied to the ADC input (in milli units).
> > +          If not present, default to 1000 (no actual gain applied).
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        default: 1000
> > +
> > +    required:
> > +      - reg
> > +
> > +    additionalProperties: false
> > +
> >  unevaluatedProperties: false
> >
> >  allOf:
> > @@ -128,7 +166,21 @@ allOf:
> >          ainc-supply: false
> >          aind-supply: false
> >
> > +  # Using channel to declare gain property only applies to adaq devices
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          not:
> > +            contains:
> > +              enum:
> > +                - adi,adaq4370-4
> > +                - adi,adaq4380-4
> > +    then:
> > +      patternProperties:
> > +        "^channel@([0-3])$": false
> > +
> >    # ad7380-4 uses refin-supply as external reference.
> > +  # adaq devices use internal reference only, derived from refin-supply
> >    # All other chips from ad738x family use refio as optional external reference.
> >    # When refio-supply is omitted, internal reference is used.
> >    - if:
> > @@ -136,6 +188,8 @@ allOf:
> >          compatible:
> >            enum:
> >              - adi,ad7380-4
> > +            - adi,adaq4370-4
> > +            - adi,adaq4380-4
> >      then:
> >        properties:
> >          refio-supply: false
> > @@ -145,6 +199,24 @@ allOf:
> >        properties:
> >          refin-supply: false
> >
> > +  # adaq devices need more supplies
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          enum:
> > +            - adi,adaq4370-4
> > +            - adi,adaq4380-4
> > +    then:
> > +      required:
> > +        - vs-p-supply
> > +        - vs-n-supply
> > +        - ldo-supply
> > +    else:
> > +      properties:
> > +        vs-p-supply: false
> > +        vs-n-supply: false
> > +        ldo-supply: false
> > +
> >  examples:
> >    - |
> >      #include <dt-bindings/interrupt-controller/irq.h>
> > @@ -169,3 +241,48 @@ examples:
> >              refio-supply = <&supply_2_5V>;
> >          };
> >      };
> > +
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        adc@0 {
> > +            compatible = "adi,adaq4380-4";
> > +            reg = <0>;
> > +
> > +            spi-cpol;
> > +            spi-cpha;
> > +            spi-max-frequency = <80000000>;
> > +
> > +            interrupts = <27 IRQ_TYPE_EDGE_FALLING>;
> > +            interrupt-parent = <&gpio0>;
> > +
> > +            vcc-supply = <&supply_3_3V>;
> > +            vlogic-supply = <&supply_3_3V>;
> > +            refin-supply = <&supply_5V>;
> > +            vs-p-supply = <&supply_5V>;
> > +            vs-n-supply = <&supply_0V>;
> > +            ldo-supply = <&supply_5V>;
> > +
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            channel@0 {
> > +                reg = <0>;
> > +                adi,gain-milli = <300>;
> > +            };
> > +
> > +            channel@2 {
> > +                reg = <2>;
> > +                adi,gain-milli = <600>;
> > +            };
> > +
> > +            channel@3 {
> > +                reg = <3>;
> > +                adi,gain-milli = <1000>;
> > +            };
> > +        };
> > +    };
> >
>





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