Re: [PATCH v3 1/9] dt-bindings: iio: adc: support the TI ADS126x ADC family

[David Lechner <dlechner@baylibre.com>]

On 8/7/26 10:58 PM, Kurt Borja wrote:
> The ADS1262 and ADS1263 are 32-bit, 38.4-kSPS delta-sigma ADCs with an
> integrated PGA, internal reference, excitation and burn-out current
> sources for sensor biasing and diagnostics. The ADS1263 adds a second,
> 24-bit delta-sigma ADC (ADC2) for background measurements.
> 

...

> +patternProperties:
> +  "^ain([0-9]|com)-supply$":
> +    description:
> +      Common-mode voltage supply connected to AIN<N> or AINCOM.
> +
> +  "^refp[1-3]-supply$":
> +    description:
> +      Positive voltage reference connected to REFP1 (AIN0), REFP2 (AIN2) or
> +      REFP3 (AIN4). If not described, its assumed to be connected to ground
> +      (0V).

Would we really have a case with a negative only reference? I would say if not
described, assume the pin is free for other use.

> +
> +  "^refn[1-3]-supply$":
> +    description:
> +      Negative voltage reference connected to REFN1 (AIN1), REFN2 (AIN3) or
> +      REFN3 (AIN5). If not described, its assumed to be connected to ground
> +      (0V).

Assumption is only true when corresponding refp supply is described. Otherwise
we should assume the pin is free for other uses.

> +
> +  "^ti,refp[1-3]-refn[1-3]-resistor-ohms$":
> +    description:
> +      Magnitude of the external reference resistor connected between REFP<N>
> +      and REFN<M>. In ratiometric configurations, such as RTD measurements, the
> +      IDAC excitation current returns through this resistor, generating the
> +      reference voltage for the conversion.
> +
> +  "^channel@[0-9]+$":
> +    $ref: /schemas/iio/adc/adc.yaml#
> +    unevaluatedProperties: false
> +
> +    properties:
> +      reg:
> +        maxItems: 1
> +
> +      single-channel:
> +        minimum: 0
> +        maximum: 10
> +
> +      common-mode-channel:
> +        minimum: 0
> +        maximum: 10
> +        default: 10
> +
> +      diff-channels:
> +        description: |
> +          In addition to the analog input pins 0 (AIN0) - 10 (AINCOM), there are
> +          special inputs that can be selected from the following values:
> +          11: Temperature sensor monitor
> +          12: Analog power supply monitor
> +          13: Digital power supply monitor
> +          14: TDAC test signal

For reasons mentioned in the reply to the cover letter, I'm not a fan of the
monitor channels here.

> +        items:
> +          minimum: 0
> +          maximum: 14
> +

...

> +      input-chopping: true
> +
> +      ti,idac-rotation:

Should we make this one a standard property like input-chopping?

> +        $ref: /schemas/types.yaml#/definitions/flag
> +        description:
> +          Automatically swap the IDAC1 and IDAC2 connections of alternate
> +          conversions. The ADC averages the alternate conversions to eliminate
> +          IDAC mismatch.
> +

...

> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        adc@0 {
> +            compatible = "ti,ads1262";
> +            reg = <0>;
> +            spi-max-frequency = <8000000>;
> +            spi-cpha;
> +            avdd-supply = <&avdd>;
> +            dvdd-supply = <&dvdd>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            interrupts-extended = <&gpio 0 IRQ_TYPE_EDGE_FALLING>;
> +            interrupt-names = "drdy";
> +
> +            /* Typical common mode voltage configuration */
> +            aincom-supply = <&ads1262_vbias>;
> +
> +            regulators {
> +                ads1262_vbias: vbias {
> +                    regulator-name = "vbias";

The node name is already "vbias" so giving regulator-name is redundant.

> +                };
> +            };
> +
> +            channel@0 {
> +                reg = <0>;
> +                single-channel = <0>;
> +                /* The VBIAS is enabled on pin 10 (AINCOM) */
> +                common-mode-channel = <10>;
> +            };
> +        };
> +    };
> +