Re: [RFC PATCH 1/3] dt-bindings: iio: adc: Add TI ADS1120 binding

[Ajith Anandhan]

On 10/31/25 1:34 AM, David Lechner wrote:
> On 10/30/25 12:12 PM, Jonathan Cameron wrote:
> > On Thu, 30 Oct 2025 22:04:09 +0530
> > Ajith Anandhan<ajithanandhan0406@xxxxxxxxx> wrote:
> >
> > > Add device tree binding documentation for the Texas Instruments
> > > ADS1120.
> > >
> > > The binding defines required properties like compatible, reg, and
> > > SPI configuration parameters.
> > >
> > > Link:https://www.ti.com/lit/gpn/ads1120
> > Datasheet:https://www.ti.com/lit/gpn/ads1120
> >
> > Is a somewhat official tag for these. Though better to put it in the dt-binding
> > doc itself as well or instead of here.
> >
> > > Signed-off-by: Ajith Anandhan<ajithanandhan0406@xxxxxxxxx>
> > > ---
> > >   .../bindings/iio/adc/ti,ads1120.yaml          | 50 +++++++++++++++++++
> > >   1 file changed, 50 insertions(+)
> > >   create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml
> > > new file mode 100644
> > > index 000000000..09285c981
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads1120.yaml
> > > @@ -0,0 +1,50 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id:http://devicetree.org/schemas/iio/adc/ti,ads1120.yaml#
> > > +$schema:http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Texas Instruments ADS1120 4-channel, 16-bit, 2kSPS ADC
> > > +
> > > +maintainers:
> > > +  - Ajith Anandhan<ajithanandhan0406@xxxxxxxxx>
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: ti,ads1120
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  spi-max-frequency:
> > > +    maximum: 4000000
> > > +
> > > +  spi-cpha: true
> > > +
> > > +  "#io-channel-cells":
> > > +    const: 1
> > Power supplies should be here and required (even if real boards
> > rely on stub regulators).
> >
> > Looks like there is an optional reference as well - so include that
> > but not as required (use internal ref if not supplied).
> Actually, there are two. REF{P,N}1 is an alternative function of
> the AIN{0,3} pins.

I'll add avdd-supply as required and vref-supply as optional to support 
both external reference configurations (REFP0/REFN0 and REFP1/REFN1).

> It is also possible that the analog power supply can be used as
> a reference source instead of the internal one.
>
> This came up recently and we glossed over it. However, I think
> it would make sense to have a flag property that means "the
> AVSS supply is of sufficient quality that it is better than
> the internal reference supply", e.g. ti,avdss-is-ref. And
> drivers can use this info to decide if they want to select it
> as the reference voltage or not.

I'll add the ti,avdss-is-ref boolean property to let the driver know 
when AVDD is suitable as a reference source.

> > There is a data ready pin as well so I'd expect an interrupt.
> There is actually two DRDY pins. One is shared with DOUT, so we
> should have two interrupts and interrupt-names so we know which
> pin is actually wired up.
Thanks for the clarification. I'll add support for up to two interrupts 
with interrupt-names ("drdy" and "dout") to handle both pin configurations.
> > All these should be in the binding from the start as we want it
> > to be as complete as possible.  The driver doesn't have to use everything
> > the binding supplies.
> Another trivial one is an optional clocks property for the external
> clock. It doesn't need clock-names since there is only one.
Will add the optional clocks property for external clock support.
> Additional bindings needed when this is used with temperature sensors
> are not so trivial though, so we don't need to add those until someone
> actually needs them.

I'll incorporate all these changes in v2. Thank you both for the 
thorough review!


--
Best Regards,
Ajith Anandhan.