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SubjectRE: [PATCH v2 1/2] dt-bindings: iio: dac: Add adi,ad3552r.yaml
Date
> -----Original Message-----
> From: Jonathan Cameron <jic23@kernel.org>
> Sent: Sunday, 10 October 2021 17:49
> To: Chindris, Mihail <Mihail.Chindris@analog.com>
> Cc: linux-kernel@vger.kernel.org; linux-iio@vger.kernel.org;
> lars@metafoo.de; Hennerich, Michael <Michael.Hennerich@analog.com>;
> Sa, Nuno <Nuno.Sa@analog.com>; Bogdan, Dragos
> <Dragos.Bogdan@analog.com>; alexandru.ardelean@analog.com; Mark
> Brown <broonie@kernel.org>
> Subject: Re: [PATCH v2 1/2] dt-bindings: iio: dac: Add adi,ad3552r.yaml
>
> On Fri, 8 Oct 2021 12:39:08 +0000
> Mihail Chindris <mihail.chindris@analog.com> wrote:
>
> > Add documentation for ad3552r
> >
> > Signed-off-by: Mihail Chindris <mihail.chindris@analog.com>
> Hi Mihael,
>
> A few comments inline.
>
> Thanks,
>
> Jonathan
>
> > ---
> > .../bindings/iio/dac/adi,ad3552r.yaml | 199 ++++++++++++++++++
> > 1 file changed, 199 insertions(+)
> > create mode 100644
> > Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> >
> > diff --git
> > a/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> > b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> > new file mode 100644
> > index 000000000000..1086e935d330
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml
> > @@ -0,0 +1,199 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) # Copyright 2020
> > +Analog Devices Inc.
> > +%YAML 1.2
> > +---
> > +$id:
> > +https://urldefense.com/v3/__http://devicetree.org/schemas/iio/dac/adi
> >
> +,ad3552r.yaml*__;Iw!!A3Ni8CS0y2Y!pqvd1NyV8G8KXIcfAtV1erPpylxLUGXD
> 1Tx5
> > +UoK2MMNNgQpv5RSyFb6NQDSL0sEuJOI$
> > +$schema:
> > +https://urldefense.com/v3/__http://devicetree.org/meta-
> schemas/core.y
> >
> +aml*__;Iw!!A3Ni8CS0y2Y!pqvd1NyV8G8KXIcfAtV1erPpylxLUGXD1Tx5UoK2
> MMNNgQ
> > +pv5RSyFb6NQDSL3G5680U$
> > +
> > +title: Analog Devices AD2552R DAC device driver
> > +
> > +maintainers:
> > + - Mihail Chindris <mihail.chindris@analog.com>
> > +
> > +description: |
> > + Bindings for the Analog Devices AD3552R DAC device. Datasheet can
> > +be
>
> Extra space before DAC, and doesn't mention the other supported part.
> One option to avoid a never ending list is "and similar."
>
> > + found here:
> > +
> > + https://www.analog.com/media/en/technical-documentation/data-
> sheets/
> > + ad3552r.pdf
>
> Good to have datasheet for the other part as well as I don't think this is a
> shared datasheet?
>
> > +
> > +properties:
> > + compatible:
> > + enum:
> > + - adi,ad3552r
> > + - adi,ad3542r
>
> Alphabetical order preferred.
>
> > +
> > + reg:
> > + maxItems: 1
> > +
> > + spi-max-frequency:
> > + maximum: 30000000
> > +
> > + reset-gpios:
> > + maxItems: 1
> > +
> > + ldac-gpios:
> > + description: |
> > + If a LDAC gpio is specified it will generate a LDAC pulse each time the
> > + trigger handler sends data to the chip.
>
> Trigger handler is a linux concept. You need to write this more generically.
> Something like.
>
> "LDAC pin is used as a hardware trigger to update a set of DACs."
>
>
> > + maxItems: 1
> > +
> > + vref-supply:
> > + description:
> > + The regulator to use as an external reference. If it does not exists the
> > + internal reference will be used. External reference must be
> > + 2.5V
> > +
> > + adi,vref-out-en:
> > + description: Vref I/O driven by internal vref to 2.5V. If not set, Vref pin
> > + will be floating.
> > + type: boolean
> > +
> > + adi,sdo-drive-strength:
> > + description: |
> > + Configure SDIO0 and SDIO1 strength levels:
> > + - 0: low SDO drive strength.
> > + - 1: medium low SDO drive strength.
> > + - 2: medium high SDO drive strength.
> > + - 3: high SDO drive strength
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + enum: [0, 1, 2, 3]
> > +
> > +patternProperties:
> > + "^channel@([0-1])$":
> > + type: object
> > + description: Configurations of the DAC Channels
> > + properties:
> > + reg:
> > + description: Channel number
> > + enum: [0, 1]
> > +
> > + custom-output-range-config:
>
> Not a generic property so I think this needs an adi prefix.

I tried with adi prefix but I get weird errors while running dt_binding_check for properties with adi prefix and with type:object
Do you have any suggestion for this issues?

> > + type: object
> > + description: Configuration of custom range when
> > + adi,output-range-microvolt is not present.
> > + The formulas for calculation the output voltages are
> > + Vout_fs = 2.5 + [(GainN + Offset/1024) * 2.5 * Rfbx * 1.03]
> > + Vout_zs = 2.5 - [(GainP + Offset/1024) * 2.5 * Rfbx * 1.03]
> > + properties:
> > + adi,gain-offset:
> > + description: Gain offset used in the above formula
> > + $ref: /schemas/types.yaml#/definitions/int32
> > + maximum: 511
> > + minimum: -511
> > + adi,gain-scaling-p:
> > + description: |
> > + Scaling p:
> > + 0: 1.0
> > + 1: 0.5
> > + 2: 0.25
> > + 3: 0.125
>
> Given this is just a mapping to a simple set of values, could we just have the
> values or express it as 1/(2^GainP) in the equation above and call it
> adi,gain-scalling-inv-log2 or something like that?
>
> If we can avoid a mapping table that is always a nice to have
>
>
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + enum: [0, 1, 2, 3]
> > + adi,gain-scaling-n:
> > + description: |
> > + Scaling p:
> > + 0: 1.0
> > + 1: 0.5
> > + 2: 0.25
> > + 3: 0.125
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + enum: [0, 1, 2, 3]
> > + adi,rfb-ohms:
> > + description: Feedback Resistor
> > + required:
> > + - adi,gain-offset
> > + - adi,gain-sacling-p
> > + - adi,gain-sacling-n
> > + - adi,rfb-ohms
> > + required:
> > + - reg
> > +
> > + oneOf:
> > + # If adi,output-range is missing, custom-output-range-config
> > + must be used
>
> adi,output-range-microvolt is missing...
>
> > + - required:
> > + - adi,output-range-microvolt
> > + - required:
> > + - custom-output-range-config
> > +
> > +allOf:
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: adi,ad3542r
> > + then:
> > + patternProperties:
> > + "^channel@([0-1])$":
> > + type: object
> > + properties:
> > + adi,output-range-microvolt:
> > + description: |
> > + Voltage output range of the channel as <minimum, maximum>
> > + Required connections:
> > + Rfb1x for: 0 to 2.5 V; 0 to 3V; 0 to 5 V;
> > + Rfb2x for: 0 to 10 V; 2.5 to 7.5V; -5 to 5 V;
> > + oneOf:
> > + - items:
> > + - const: 0
> > + - enum: [2500000, 3000000, 5000000, 10000000]
> > + - items:
> > + - const: -2500000
> > + - const: 7500000
> > + - items:
> > + - const: -5000000
> > + - const: 5000000
> > + required:
> > + - adi,output-range-microvolt
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: adi,ad3552r
> > + then:
> > + patternProperties:
> > + "^channel@([0-1])$":
> > + type: object
> > + properties:
> > + adi,output-range-microvolt: |
> > + Voltage output range of the channel as <minimum, maximum>
> > + Required connections:
> > + Rfb1x for: 0 to 2.5 V; 0 to 5 V;
> > + Rfb2x for: 0 to 10 V; -5 to 5 V;
> > + Rfb4x for: -10 to 10V
> > + oneOf:
> > + - items:
> > + - const: 0
> > + - enum: [2500000, 5000000, 10000000]
> > + - items:
> > + - const: -5000000
> > + - const: 5000000
> > + - items:
> > + - const: -10000000
> > + - const: 10000000
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - spi-max-frequency
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + ad3552r {
> > + compatible = "adi,ad3552r";
> > + reg = <0>;
> > + spi-max-frequency = <20000000>;
> > + channel@0 {
> > + reg = <0>;
> > + adi,output-range-microvolt = <0 10000000>;
> > + };
> > + channel@1 {
> > + reg = <1>;
> > + custom-output-range-config {
> > + adi,gain-offset = <5>;
> > + adi,gain-scaling-p = <1>;
> > + adi,gain-scaling-n = <2>;
> > + adi,rfb-ohms = <1>;
> > + };
> > + };
> > + };
> > +...

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