dt-bindings: firmware: arm,scmi: Introduce more transport properties

Depending on specific hardware and firmware design choices, it may be
possible for different platforms to end up having different requirements
regarding the same transport characteristics.

Introduce max-msg-size and max-msg properties to describe such platform
specific transport constraints, since they cannot be discovered otherwise.

Reviewed-by: Rob Herring (Arm) <[email protected]>
Signed-off-by: Cristian Marussi <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>

Author: cris-ma

Documentation/devicetree/bindings/firmware/arm,scmi.yaml

@@ -131,6 +131,21 @@ properties:
       be a non-zero value if set.
     minimum: 1
 
+  arm,max-msg-size:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      An optional value, expressed in bytes, representing the maximum size
+      allowed for the payload of messages transmitted on this transport.
+
+  arm,max-msg:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      An optional value representing the maximum number of concurrent in-flight
+      messages allowed by this transport; this number represents the maximum
+      number of concurrently outstanding messages that the server can handle on
+      this platform. If set, the value should be non-zero.
+    minimum: 1
+
   arm,smc-id:
     $ref: /schemas/types.yaml#/definitions/uint32
     description: