When one or multiple Auxiliary ADC IPs are embedded in a SPMI PMIC
it is reachable at a specific address.

Allow specifying the `reg` property and make it a required one for
MediaTek MT6363/6373 PMICs as those communicate over SPMI and also
disallow it for the others (as it wouldn't be applicable).

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 .../iio/adc/mediatek,mt6359-auxadc.yaml         | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml b/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml
index 5d4ab701f51a..e685e5ee224a 100644
--- a/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/mediatek,mt6359-auxadc.yaml

@@ -25,6 +25,9 @@ properties:
       - mediatek,mt6363-auxadc
       - mediatek,mt6373-auxadc
 
+  reg:
+    maxItems: 1
+
   "#io-channel-cells":
     const: 1
 

@@ -33,3 +36,17 @@ required:
   - "#io-channel-cells"
 
 additionalProperties: false
+
+if:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - mediatek,mt6363-auxadc
+          - mediatek,mt6373-auxadc
+then:
+  required:
+    - reg
+else:
+  properties:
+    reg: false

-- 
2.51.0