Re: [PATCH v2 5/8] dt-bindings: iio: adc: add ti,ads122c14

[Conor Dooley <conor@kernel.org>]

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On Thu, Jun 25, 2026 at 04:55:07PM -0500, David Lechner (TI) wrote:
> Add new bindings for ti,ads122c14 and similar devices.
> 
> This is an ADC that is primarily intended for use with temperature
> sensors. There are a few unusual properties because of this. In
> particular, the reference voltage source and current output requirements
> can be different for each measurement, so these are included in the
> channel bindings.
> 
> The REFP/REFN reference voltage is usually just connected to a resistor
> that is being driven by the ADC's current outputs, so there is special
> property for this case rather than requiring a regulator to be defined
> to represent that.
> 
> ti,vref-source is reused from ti,tlv320adcx140.yaml (otherwise might
> have preferred an enum of strings).
> 
> Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
> ---
> 
> v2 changes:
> * Added ti, vendor prefix when appropriate.
> * Others are now standardized properties from adc.yaml.
> * Moved top-level unevaluatedProperties.
> * Fixed some issues with the channel@ matching and reg property.
> * Dropped description on bipolar property.
> * Renamed currnet-chopping to input-channel-rotation.
> * Drop header file and use string enum instead for reference-sources.
> * Added burn-out-current-nanoamp property.
> * Drop allOf: and just use oneOf: directly.
> * Fix inconsistent indentation in the examples.
> ---
>  .../devicetree/bindings/iio/adc/ti,ads112c14.yaml  | 205 +++++++++++++++++++++
>  MAINTAINERS                                        |   6 +
>  2 files changed, 211 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
> new file mode 100644
> index 000000000000..59ee4d652a08
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
> @@ -0,0 +1,205 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/ti,ads112c14.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Texas Instruments' ADS112C14 and similar ADC chips
> +
> +description: |
> +  Supports the following Texas Instruments' ADC chips:
> +  - ADS112C14 (16-bit)
> +  - ADS122C14 (24-bit)
> +
> +  https://www.ti.com/lit/ds/symlink/ads122c14.pdf
> +
> +  These chips are primarily designed for use with temperature sensors such as
> +  RTDs and thermocouples. The channel bindings reflect this in that each channel
> +  represents the conditions required to make a measurement rather than strictly
> +  just the physical input channels.
> +
> +maintainers:
> +  - David Lechner <dlechner@baylibre.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - ti,ads112c14
> +      - ti,ads122c14
> +
> +  reg:
> +    items:
> +      - minimum: 0x40
> +        maximum: 0x47
> +
> +  clocks:
> +    maxItems: 1
> +    description: Optional external clock connected to GPIO3 pin.
> +
> +  avdd-supply: true
> +  dvdd-supply: true
> +
> +  refp-supply: true
> +  refn-supply: true
> +
> +  ti,refp-refn-resistor-ohms:
> +    description:
> +      The resistance of the external resistor between REFP and REFN when using
> +      resistor bridge driven by current outputs for RTD measurements.
> +
> +  interrupts:
> +    minItems: 1
> +    items:
> +      - description: FAULT interrupt (GPIO2 pin)
> +      - description: DRDY interrupt (GPIO3 pin)
> +
> +  interrupt-names:
> +    minItems: 1
> +    maxItems: 2
> +    items:
> +      enum: [fault, drdy]
> +
> +  gpio-controller: true
> +  '#gpio-cells':
> +    const: 2
> +
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +patternProperties:
> +  ^channel@[0-7a-f]$:

How does this work/what's the intention here?

0-7 I get, why a-f but not 8 or 9?

> +    $ref: adc.yaml
> +
> +    unevaluatedProperties: false
> +
> +    properties:
> +      reg:
> +        items:
> +          - maximum: 15 # arbitrary limit, channel@ can be any combination of AIN0-AIN7
> +
> +      single-channel:
> +        maximum: 7
> +
> +      diff-channels:
> +        items:
> +          maximum: 7
> +
> +      bipolar: true
> +
> +      input-channel-rotation: true
> +
> +      excitation-channels:
> +        maxItems: 2
> +        items:
> +          maximum: 7
> +
> +      excitation-current-nanoamp:
> +        maxItems: 2
> +        items:
> +          enum: [1000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000,
> +                 90000, 100000, 200000, 300000, 400000, 500000, 600000, 700000,
> +                 800000, 900000, 1000000]
> +
> +      burn-out-current-nanoamp:
> +        enum: [200, 1000, 10000]
> +
> +      reference-sources:
> +        items:
> +          - enum: [internal-2.5v, internal-1.25v, external, avdd]
> +            default: internal-2.5v
> +
> +    dependencies:
> +      excitation-channels: [ excitation-current-nanoamp ]
> +      excitation-current-nanoamp: [ excitation-channels ]
> +
> +    oneOf:
> +      - required: [ single-channel ]
> +      - required: [ diff-channels ]
> +
> +unevaluatedProperties: false
> +
> +required:
> +  - compatible

reg?

> +  - avdd-supply
> +  - dvdd-supply
> +
> +dependencies:
> +  refn-supply: [ refp-supply ]
> +
> +oneOf:
> +  - required: [ refp-supply ]
> +  - required: [ "ti,refp-refn-resistor-ohms" ]
> +  - properties:
> +      refp-supply: false
> +      refn-supply: false
> +      ti,refp-refn-resistor-ohms: false

I assume you've tested this to make sure it enforces the behaviour that
you want?

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