[PATCH RFC v2 0/3] dt-bindings: iio: adc: Add reference, excitation and burn-out properties

[PATCH RFC v2 0/3] dt-bindings: iio: adc: Add reference, excitation and burn-out properties

[Kurt Borja]

Hi all,

After submitting a patch series adding support for TI ADS126X ADCs [1],
I was made aware by David [2] that at least two more chip families,
ads1220 [3] and ads1x2c14, share very similar features (though these
chips are not really compatible between them). After that, I found one
more chip with the same features which is already upstream, the
AD4170-4.

As David explained in [2], these chips are intended to be used with
RTDs, thermocouples or other resistive sensors so they share the
following per-channel features:

  - Configurable reference selection
  - Burn-out Current Sources (BOCS) for diagnostic purpuses
  - Excitation current sources (usually called IDACs TI) for sensor
    current biasing

Given that these three features are present in all four devices and
three of these drivers are still under review, my proposal is to have
these features be described in adc.yaml and have this series merged
before the three others [1] [2] [3].

This series is sent as RFC because I still don't have much experience
with dt-bindings and I don't know if this approach or the properties are
general enough to be described like this.

No dependencies between properties were provided because not all devices
may be able to configure each one of them.

[1] https://lore.kernel.org/linux-iio/20260612-ads126x-v1-0-894c788d03ed@gmail.com/
[2] https://lore.kernel.org/linux-iio/20260615-iio-adc-ti-ads122c14-v1-0-e6bdadf7cb2b@baylibre.com/
[3] https://lore.kernel.org/linux-iio/20260610151342.44274-1-zizuzacker@gmail.com/

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
v2:
  - reference-source is now a string-array and now presents a couple of
    quick examples
  - excitation-* properties now do not enforce arbitrary limits
  - Dropped burn-out-current-polarity because it was not general enough
  - I kept burn-out-current-microamp because the discussion around it is
    still ongoing

v1: https://patch.msgid.link/20260618-new-channel-props-v1-0-963c1b5cf40a@gmail.com

---
Kurt Borja (3):
      dt-bindings: iio: adc: Add reference-source property
      dt-bindings: iio: adc: Add excitation current sources properties
      dt-bindings: iio: adc: Add burn-out current properties

 Documentation/devicetree/bindings/iio/adc/adc.yaml | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)
---
base-commit: a50909aa46dec46de3c73235fc15a7d6f763d996
change-id: 20260618-new-channel-props-4fbd52020da2

-- 
Thanks, 
 ~ Kurt

[PATCH RFC v2 1/3] dt-bindings: iio: adc: Add reference-source property

[Kurt Borja]

Some ADCs have configurable voltage reference sources for each channel.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index b9bc02b5b07a4c7..fdad6b8276c934c 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -73,6 +73,19 @@ properties:
       device design and can interact with other characteristics such as
       settling time.
 
+  reference-source:
+    $ref: /schemas/types.yaml#/definitions/string-array
+    maxItems: 2
+    minItems: 1
+    description:
+      Indicates the voltage reference source or sources for this channel. Some
+      ADCs usually allow choosing between internal reference sources or a pair
+      of external pins.
+
+      If a single value is provided, it represents a single voltage reference
+      source. If two values are provided, the first one corresponds to the
+      positive source and the second to the negative source.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.54.0

[PATCH RFC v2 2/3] dt-bindings: iio: adc: Add excitation current sources properties

[Kurt Borja]

Some ADCs incorporate current sources that provide excitation current to
resistive temperature devices (RTDs), thermistors, diodes and other
resistive sensors that require constant current biasing.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index fdad6b8276c934c..160a8cfa9842a86 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -86,6 +86,25 @@ properties:
       source. If two values are provided, the first one corresponds to the
       positive source and the second to the negative source.
 
+  excitation-channels:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description:
+      Excitation current sources provide current to resistive temperature
+      devices (RTDs), thermistors, diodes and other resistive sensors that
+      require constant current biasing.
+
+      This array describes the mux configuration of the excitation current
+      sources.
+
+  excitation-current-microamp:
+    description:
+      Excitation current sources provide current to resistive temperature
+      devices (RTDs), thermistors, diodes and other resistive sensors that
+      require constant current biasing.
+
+      This array describes the current configuration of the excitation current
+      sources or the single matched current for all sources.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.54.0

[PATCH RFC v2 3/3] dt-bindings: iio: adc: Add burn-out current properties

[Kurt Borja]

Some ADCs incorporate burn-out current sources that provide current to
the channel's input pins for open-circuit or short-circuit detection.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index 160a8cfa9842a86..9240f569d4ab7af 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -105,6 +105,12 @@ properties:
       This array describes the current configuration of the excitation current
       sources or the single matched current for all sources.
 
+  burn-out-current-microamp:
+    maxItems: 1
+    description:
+      Burn-out current sources provide current to the channel's input pins for
+      open-circuit or short-circuit detection.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.54.0

Re: [PATCH RFC v2 0/3] dt-bindings: iio: adc: Add reference, excitation and burn-out properties

[David Lechner]

On 6/22/26 2:30 PM, Kurt Borja wrote:
> Hi all,
> 
> After submitting a patch series adding support for TI ADS126X ADCs [1],
> I was made aware by David [2] that at least two more chip families,
> ads1220 [3] and ads1x2c14, share very similar features (though these
> chips are not really compatible between them). After that, I found one
> more chip with the same features which is already upstream, the
> AD4170-4.
> 
> As David explained in [2], these chips are intended to be used with
> RTDs, thermocouples or other resistive sensors so they share the
> following per-channel features:
> 
>   - Configurable reference selection
>   - Burn-out Current Sources (BOCS) for diagnostic purpuses
>   - Excitation current sources (usually called IDACs TI) for sensor
>     current biasing
> 
> Given that these three features are present in all four devices and
> three of these drivers are still under review, my proposal is to have
> these features be described in adc.yaml and have this series merged
> before the three others [1] [2] [3].
> 
> This series is sent as RFC because I still don't have much experience
> with dt-bindings and I don't know if this approach or the properties are
> general enough to be described like this.

It will probably be easier if I just include these patches when I do
v2 of my series (if you don't mind me tweaking them a bit).

> 
> No dependencies between properties were provided because not all devices
> may be able to configure each one of them.
> 
> [1] https://lore.kernel.org/linux-iio/20260612-ads126x-v1-0-894c788d03ed@gmail.com/
> [2] https://lore.kernel.org/linux-iio/20260615-iio-adc-ti-ads122c14-v1-0-e6bdadf7cb2b@baylibre.com/
> [3] https://lore.kernel.org/linux-iio/20260610151342.44274-1-zizuzacker@gmail.com/
> 
> Signed-off-by: Kurt Borja <kuurtb@gmail.com>
> ---
> v2:
>   - reference-source is now a string-array and now presents a couple of
>     quick examples
>   - excitation-* properties now do not enforce arbitrary limits
>   - Dropped burn-out-current-polarity because it was not general enough
>   - I kept burn-out-current-microamp because the discussion around it is
>     still ongoing
> 
> v1: https://patch.msgid.link/20260618-new-channel-props-v1-0-963c1b5cf40a@gmail.com
> 
> ---
> Kurt Borja (3):
>       dt-bindings: iio: adc: Add reference-source property
>       dt-bindings: iio: adc: Add excitation current sources properties
>       dt-bindings: iio: adc: Add burn-out current properties
> 
>  Documentation/devicetree/bindings/iio/adc/adc.yaml | 38 ++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> ---
> base-commit: a50909aa46dec46de3c73235fc15a7d6f763d996
> change-id: 20260618-new-channel-props-4fbd52020da2
> 

Re: [PATCH RFC v2 1/3] dt-bindings: iio: adc: Add reference-source property

[David Lechner]

On 6/22/26 2:30 PM, Kurt Borja wrote:
> Some ADCs have configurable voltage reference sources for each channel.
> 
> Signed-off-by: Kurt Borja <kuurtb@gmail.com>
> ---
>  Documentation/devicetree/bindings/iio/adc/adc.yaml | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> index b9bc02b5b07a4c7..fdad6b8276c934c 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> @@ -73,6 +73,19 @@ properties:
>        device design and can interact with other characteristics such as
>        settling time.
>  
> +  reference-source:

Since this is an array, the name should be `reference-sources`.

> +    $ref: /schemas/types.yaml#/definitions/string-array
> +    maxItems: 2
> +    minItems: 1

Maybe minItems here is OK, but I don't think we should put maxItems here.
This way, it stays more flexible for other use cases.

> +    description:
> +      Indicates the voltage reference source or sources for this channel. Some
> +      ADCs usually allow choosing between internal reference sources or a pair
> +      of external pins.
> +
> +      If a single value is provided, it represents a single voltage reference
> +      source. If two values are provided, the first one corresponds to the
> +      positive source and the second to the negative source.
> +
>  anyOf:
>    - oneOf:
>        - required:
> 

Re: [PATCH RFC v2 2/3] dt-bindings: iio: adc: Add excitation current sources properties

[David Lechner]

On 6/22/26 2:30 PM, Kurt Borja wrote:
> Some ADCs incorporate current sources that provide excitation current to
> resistive temperature devices (RTDs), thermistors, diodes and other
> resistive sensors that require constant current biasing.
> 
> Signed-off-by: Kurt Borja <kuurtb@gmail.com>
> ---
>  Documentation/devicetree/bindings/iio/adc/adc.yaml | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> index fdad6b8276c934c..160a8cfa9842a86 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> @@ -86,6 +86,25 @@ properties:
>        source. If two values are provided, the first one corresponds to the
>        positive source and the second to the negative source.
>  
> +  excitation-channels:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    description:
> +      Excitation current sources provide current to resistive temperature
> +      devices (RTDs), thermistors, diodes and other resistive sensors that
> +      require constant current biasing.
> +
> +      This array describes the mux configuration of the excitation current
> +      sources.
> +
> +  excitation-current-microamp:

As seen in adi,ltc2983.yaml, this actually needs to be nanoamp to be able
to be flexible for all parts.

> +    description:
> +      Excitation current sources provide current to resistive temperature
> +      devices (RTDs), thermistors, diodes and other resistive sensors that
> +      require constant current biasing.
> +
> +      This array describes the current configuration of the excitation current
> +      sources or the single matched current for all sources.
> +
>  anyOf:
>    - oneOf:
>        - required:
> 

Re: [PATCH RFC v2 3/3] dt-bindings: iio: adc: Add burn-out current properties

[David Lechner]

On 6/22/26 2:30 PM, Kurt Borja wrote:
> Some ADCs incorporate burn-out current sources that provide current to
> the channel's input pins for open-circuit or short-circuit detection.
> 
> Signed-off-by: Kurt Borja <kuurtb@gmail.com>
> ---
>  Documentation/devicetree/bindings/iio/adc/adc.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> index 160a8cfa9842a86..9240f569d4ab7af 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
> @@ -105,6 +105,12 @@ properties:
>        This array describes the current configuration of the excitation current
>        sources or the single matched current for all sources.
>  
> +  burn-out-current-microamp:

This also needs to be nanoamp.

> +    maxItems: 1
> +    description:
> +      Burn-out current sources provide current to the channel's input pins for
> +      open-circuit or short-circuit detection.
> +
>  anyOf:
>    - oneOf:
>        - required:
> 

Re: [PATCH RFC v2 0/3] dt-bindings: iio: adc: Add reference, excitation and burn-out properties

[Kurt Borja]

On Mon Jun 22, 2026 at 2:38 PM -05, David Lechner wrote:
> On 6/22/26 2:30 PM, Kurt Borja wrote:
>> Hi all,
>> 
>> After submitting a patch series adding support for TI ADS126X ADCs [1],
>> I was made aware by David [2] that at least two more chip families,
>> ads1220 [3] and ads1x2c14, share very similar features (though these
>> chips are not really compatible between them). After that, I found one
>> more chip with the same features which is already upstream, the
>> AD4170-4.
>> 
>> As David explained in [2], these chips are intended to be used with
>> RTDs, thermocouples or other resistive sensors so they share the
>> following per-channel features:
>> 
>>   - Configurable reference selection
>>   - Burn-out Current Sources (BOCS) for diagnostic purpuses
>>   - Excitation current sources (usually called IDACs TI) for sensor
>>     current biasing
>> 
>> Given that these three features are present in all four devices and
>> three of these drivers are still under review, my proposal is to have
>> these features be described in adc.yaml and have this series merged
>> before the three others [1] [2] [3].
>> 
>> This series is sent as RFC because I still don't have much experience
>> with dt-bindings and I don't know if this approach or the properties are
>> general enough to be described like this.
>
> It will probably be easier if I just include these patches when I do
> v2 of my series (if you don't mind me tweaking them a bit).

Sure, that's fine by me. I'll add a dependency to your series with b4.

Want me to send one more version addressing your comments before you
take it in?

-- 
Thanks,
 ~ Kurt

Re: [PATCH RFC v2 0/3] dt-bindings: iio: adc: Add reference, excitation and burn-out properties

[David Lechner]

On 6/22/26 2:58 PM, Kurt Borja wrote:
> On Mon Jun 22, 2026 at 2:38 PM -05, David Lechner wrote:
>> On 6/22/26 2:30 PM, Kurt Borja wrote:
>>> Hi all,
>>>
>>> After submitting a patch series adding support for TI ADS126X ADCs [1],
>>> I was made aware by David [2] that at least two more chip families,
>>> ads1220 [3] and ads1x2c14, share very similar features (though these
>>> chips are not really compatible between them). After that, I found one
>>> more chip with the same features which is already upstream, the
>>> AD4170-4.
>>>
>>> As David explained in [2], these chips are intended to be used with
>>> RTDs, thermocouples or other resistive sensors so they share the
>>> following per-channel features:
>>>
>>>   - Configurable reference selection
>>>   - Burn-out Current Sources (BOCS) for diagnostic purpuses
>>>   - Excitation current sources (usually called IDACs TI) for sensor
>>>     current biasing
>>>
>>> Given that these three features are present in all four devices and
>>> three of these drivers are still under review, my proposal is to have
>>> these features be described in adc.yaml and have this series merged
>>> before the three others [1] [2] [3].
>>>
>>> This series is sent as RFC because I still don't have much experience
>>> with dt-bindings and I don't know if this approach or the properties are
>>> general enough to be described like this.
>>
>> It will probably be easier if I just include these patches when I do
>> v2 of my series (if you don't mind me tweaking them a bit).
> 
> Sure, that's fine by me. I'll add a dependency to your series with b4.
> 
> Want me to send one more version addressing your comments before you
> take it in?
> 

No need. I don't mind fixing it up.

Re: [PATCH RFC v2 0/3] dt-bindings: iio: adc: Add reference, excitation and burn-out properties

[Kurt Borja]

On Mon Jun 22, 2026 at 3:01 PM -05, David Lechner wrote:
> On 6/22/26 2:58 PM, Kurt Borja wrote:
>> On Mon Jun 22, 2026 at 2:38 PM -05, David Lechner wrote:
>>> On 6/22/26 2:30 PM, Kurt Borja wrote:
>>>> Hi all,
>>>>
>>>> After submitting a patch series adding support for TI ADS126X ADCs [1],
>>>> I was made aware by David [2] that at least two more chip families,
>>>> ads1220 [3] and ads1x2c14, share very similar features (though these
>>>> chips are not really compatible between them). After that, I found one
>>>> more chip with the same features which is already upstream, the
>>>> AD4170-4.
>>>>
>>>> As David explained in [2], these chips are intended to be used with
>>>> RTDs, thermocouples or other resistive sensors so they share the
>>>> following per-channel features:
>>>>
>>>>   - Configurable reference selection
>>>>   - Burn-out Current Sources (BOCS) for diagnostic purpuses
>>>>   - Excitation current sources (usually called IDACs TI) for sensor
>>>>     current biasing
>>>>
>>>> Given that these three features are present in all four devices and
>>>> three of these drivers are still under review, my proposal is to have
>>>> these features be described in adc.yaml and have this series merged
>>>> before the three others [1] [2] [3].
>>>>
>>>> This series is sent as RFC because I still don't have much experience
>>>> with dt-bindings and I don't know if this approach or the properties are
>>>> general enough to be described like this.
>>>
>>> It will probably be easier if I just include these patches when I do
>>> v2 of my series (if you don't mind me tweaking them a bit).
>> 
>> Sure, that's fine by me. I'll add a dependency to your series with b4.
>> 
>> Want me to send one more version addressing your comments before you
>> take it in?
>> 
>
> No need. I don't mind fixing it up.

Thanks :)

-- 
Thanks,
 ~ Kurt