Re: [PATCH 1/2] dt-bindings: iio: adc: ti,ads112c04: Add binding for ADS112C04

Hi David,
Thank you for the review and for pointing me to your ADS112C14 work!
It is incredibly helpful as a reference.

On Tue, Jul 28, 2026 at 10:48 PM David Lechner <[email protected]> wrote:
>
> On 7/28/26 3:01 AM, Kyle Hsieh wrote:
> > Add device tree binding documentation for Texas Instruments ADS112C04
> > I2C Analog-to-Digital Converters.
>
> If you haven't seen it already, I'm currently working on ADS112C14
> which is a more complex, but otherwise very similar version of this
> chip.
>
> I think the differences are enough that it would be quite messy to
> try to share DT bindings and code, so OK with me to proceed with
> new bindings and driver. But we should try to make the use all of
> the same conventions as much as we can. (And to make maintainers
> happy, explain this in the cover letter so they don't ask why we
> we need a new bindings/driver.)
>
> For reference here are the bindings for that:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/tree/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml?h=testing
>
I completely agree it is best to keep them as separate drivers due to
the hardware differences. I will explain this decision and mention your
ADS112C14 work in the next patch cover letter to avoid any confusion.
> >
> > These devices provide 4-channel, 16-bit delta-sigma ADCs with an I2C
> > interface, programmable gain amplifier (PGA), and data-ready (DRDY)
> > interrupt output.
> >
> > Signed-off-by: Kyle Hsieh <[email protected]>
> > ---
> >  .../devicetree/bindings/iio/adc/ti,ads112c04.yaml  | 76 ++++++++++++++++++++++
> >  1 file changed, 76 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads112c04.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads112c04.yaml
> > new file mode 100644
> > index 000000000000..55842fca1215
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads112c04.yaml
> > @@ -0,0 +1,76 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/iio/adc/ti,ads112c04.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Texas Instruments ADS112C04 ADC
> > +
> > +maintainers:
> > +  - Kyle Hsieh <[email protected]>
> > +
> > +description: |
> > +  The ADS112C04 (16-bit) are precision analog-to-digital converters (ADCs)
> > +  with an I2C interface. They feature a flexible input multiplexer, a
> > +  low-noise programmable gain amplifier (PGA), two programmable excitation
> > +  current sources, a voltage reference, and a precision temperature sensor.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - ti,ads112c04
> > +
> > +  reg:
> > +    maxItems: 1
> > +    description: I2C address of the device.
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +    description:
> > +      Data ready (DRDY) interrupt output. It is asserted low when a new
> > +      conversion is ready.
> > +
> > +  "#io-channel-cells":
> > +    const: 1
> > +
> > +  reset-gpios:
> > +    maxItems: 1
> > +    description:
> > +      GPIO connected to the RESET pin. Active low.
> > +
> > +  avdd-supply:
> > +    description: Analog power supply (AVDD).
> > +
> > +  dvdd-supply:
> > +    description: Digital power supply (DVDD).
> > +
> > +  vref-supply:
> > +    description: External reference power supply (connected to REFP/REFN).
>
> VREF is an internal signal. Technically, these are REFP and REFN and both
> could have a supply connected to them. Also, there could be a resistor
> connected across these instead of a supply. See ti,refp-refn-resistor-ohms
> in ADS112C14 bindings and 3-wire RTD example in the datasheet (figure 74).
>
> Additionally, we need channel properties to describe a bit about what is
> connected to each AINn pin.  We will need single-channel, diff-channels,
> excitation-channels, excitation-current-nanoamp, and reference-sources
> similar to ADS112C14.
>
Understood. I will drop `vref-supply` and refer ADS112C14 implement  to
reflect the physical hardware accurately.
I will also add the child node pattern for dynamic channel configuration
 matching your conventions.
> > +
> > +required:
> > +  - compatible
> > +  - reg
>
> avdd-supply and dvdd-supply are required to power the device.
>
Makes sense. I will add `avdd-supply` and `dvdd-supply` to the required
list in the next version.
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        adc@40 {
> > +            compatible = "ti,ads112c04";
> > +            reg = <0x40>;
> > +            interrupt-parent = <&gpio>;
> > +            interrupts = <12 IRQ_TYPE_EDGE_FALLING>;
> > +            #io-channel-cells = <1>;
> > +            reset-gpios = <&gpio 13 GPIO_ACTIVE_LOW>;
> > +            avdd-supply = <&vdd_3v3_reg>;
> > +            dvdd-supply = <&vdd_3v3_reg>;
> > +            vref-supply = <&vref_reg>;
> > +        };
> > +    };
> > +...
> >
>
Thanks again for the guidance!
Best regards,
Kyle Hsieh