[PATCH v4 2/8] dt-bindings: iio: adc: Add excitation current sources properties

[David Lechner]

From: Kurt Borja <kuurtb@xxxxxxxxx>

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@xxxxxxxxx>
Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Signed-off-by: David Lechner (TI) <dlechner@xxxxxxxxxxxx>
---
v4 changes:
* Add sentence about values being pins like diff-channels and
  single-channel properties.

v2 changes (compared to Kurt's RFC v2):
* Make units nanoamps instead of microamps to fit known devices.
* Drop bit about allowing single value for multiple channels.
* Add bit about semantics of the array index.
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index 8f608bf0b24d..9f7196d61ac3 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -80,6 +80,27 @@ properties:
       ADCs usually allow choosing between internal reference sources or a pair
       of external pins.
 
+  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. The values correspond to pins similar to the diff-channels and
+      single-channel properties.
+
+  excitation-current-nanoamp:
+    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. The index in the array corresponds to the same index in the
+      excitation-channels array.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.43.0