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

[David Lechner]

On 6/26/26 11:18 AM, Conor Dooley wrote:
> 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@xxxxxxxxxxxx>
>> ---
>>
>> 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@xxxxxxxxxxxx>
>> +
>> +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?

bah, just a typo, not intentional

Should be [0-9a-f] to match maximum: 15 on reg.

> 
>> +    $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?

I thought reg being required by i2c-controller.yaml was already good enough.

https://github.com/devicetree-org/dt-schema/blob/2203c1720f4ebeebd7f8d10e9dc1812993482fab/dtschema/schemas/i2c/i2c-controller.yaml#L219

> 
>> +  - 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?


yes