[PATCH v2 1/3] dt-bindings: iio: adc: Add syscon property for multi-SCU SoCs

[Billy Tsai]

The ADC's reference-voltage trimming data lives in a System Control
Unit (SCU) register. SoCs with a single SCU instance let the driver
locate it without any additional information, but SoCs such as AST2700
that expose more than one SCU node need an explicit phandle to
disambiguate which one holds the trimming data.

Add an "aspeed,trim-syscon" phandle property, and require it for the
AST2700 compatibles since they are the first multi-SCU SoCs supported
by this driver.

Signed-off-by: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>
Assisted-by: Claude:claude-sonnet-5
---
 .../devicetree/bindings/iio/adc/aspeed,ast2600-adc.yaml | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/aspeed,ast2600-adc.yaml b/Documentation/devicetree/bindings/iio/adc/aspeed,ast2600-adc.yaml
index 249101b55cf4e..140d7034e2196 100644
--- a/Documentation/devicetree/bindings/iio/adc/aspeed,ast2600-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/aspeed,ast2600-adc.yaml
@@ -67,6 +67,11 @@ properties:
     description:
       Inform the driver that last channel will be used to sensor battery.
 
+  aspeed,trim-syscon:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle to the SCU holding the ADC's reference-voltage trimming data.
+
 required:
   - compatible
   - reg
@@ -74,6 +79,18 @@ required:
   - resets
   - "#io-channel-cells"
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - aspeed,ast2700-adc0
+              - aspeed,ast2700-adc1
+    then:
+      required:
+        - aspeed,trim-syscon
+
 additionalProperties: false
 
 examples:

-- 
2.34.1