diff --git a/Documentation/devicetree/bindings/serial/pl011.yaml b/Documentation/devicetree/bindings/serial/pl011.yaml
index d8aed84abcd32f4cd7a0d4c17f530e39af091448..80af728598764a006e82a0523815ea88fc2b225a 100644
--- a/Documentation/devicetree/bindings/serial/pl011.yaml
+++ b/Documentation/devicetree/bindings/serial/pl011.yaml
@@ -94,6 +94,12 @@ properties:
   resets:
     maxItems: 1
 
+  reg-io-width:
+    description:
+      The size (in bytes) of the IO accesses that should be performed
+      on the device.
+    enum: [1, 4]
+
 required:
   - compatible
   - reg