[PATCH v4 2/2] dt-bindings: Update scmi node description

[Oleksii Moisieiev]

Add '#domain-cells' property description to the scmi node.
This property makes scmi node as domain controller provider, which allows
consumers to provide scmi node with the device_ids of the devices, which are
using scmi protocols to control clocks/resets/power-domains etc.
The device_ids could be used to set the device permissions for the
Fimware using BASE_SET_DEVICE_PERMISSIONS message (see 4.2.2.10 of [0]).
Device permissions management described in DEN 0056, Section 4.2.2.10 [0].

For SCMI this property is used by Trusted Agent to set the device permissions
for the Non-Trusted Agents.
Trusted and non-trusted Agent terms described in Section 4.1.1 [0].

[0] https://developer.arm.com/documentation/den0056/latest

Signed-off-by: Oleksii Moisieiev <oleksii_moisieiev@xxxxxxxx>
---
Changes v1 -> V2:
   - update parameter name, made it xen-specific
   - add xen vendor bindings

Changes V2 -> V3:
   - update parameter name, make it generic
   - update parameter format, add link to controller
   - do not include xen vendor bindings as already upstreamed

Changes V3 -> V4:
   - introduce domain controller provider/consumer device tree bindings
   - making scmi node to act as domain controller provider when the
     device permissions should be configured
---
 .../bindings/firmware/arm,scmi.yaml           | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
index 5c4c6782e052..89589ed81b4e 100644
--- a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
+++ b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
@@ -78,6 +78,14 @@ properties:
   '#size-cells':
     const: 0
 
+  '#domain-cells':
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Number of cells in a domain controller specifier.
+      Set const to 1 here for nodes providing the device id, needed for
+      the BASE_SET_DEVICE_PERMISSIONS message (see 4.2.2.10 of [0]).
+    const: 1
+
   arm,smc-id:
     $ref: /schemas/types.yaml#/definitions/uint32
     description:
@@ -344,4 +352,21 @@ examples:
         };
     };
 
+  - |
+    firmware {
+        scmi_link: scmi {
+            compatible = "arm,scmi-smc";
+            shmem = <&cpu_scp_lpri0 &cpu_scp_lpri1>;
+            arm,smc-id = <0xc3000001>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+            #domain-cells = <1>;
+        };
+    };
+
+    foo@0 {
+      reg = <0x0 0x10>;
+      domain-0 = <&scmi_link 1>;
+    };
 ...
-- 
2.27.0