dt-bindings: arm: Add OP-TEE transport for SCMI

Introduce compatible "linaro,scmi-optee" for SCMI transport channel
based on an OP-TEE service invocation. The compatible mandates a
channel ID defined with property "linaro,optee-channel-id".

Link: https://lore.kernel.org/r/20211028140009.23331-1-etienne.carriere@linaro.org
Cc: devicetree@vger.kernel.org
Cc: Rob Herring <robh+dt@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

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

@@ -38,6 +38,9 @@ properties:
                      The virtio transport only supports a single device.
         items:
           - const: arm,scmi-virtio
+      - description: SCMI compliant firmware with OP-TEE transport
+        items:
+          - const: linaro,scmi-optee
 
   interrupts:
     description:
@@ -83,6 +86,11 @@ properties:
     description:
       SMC id required when using smc or hvc transports
 
+  linaro,optee-channel-id:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Channel specifier required when using OP-TEE transport.
+
   protocol@11:
     type: object
     properties:
@@ -195,6 +203,12 @@ patternProperties:
         minItems: 1
         maxItems: 2
 
+      linaro,optee-channel-id:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description:
+          Channel specifier required when using OP-TEE transport and
+          protocol has a dedicated communication channel.
+
     required:
       - reg
 
@@ -226,6 +240,16 @@ else:
       - arm,smc-id
       - shmem
 
+  else:
+    if:
+      properties:
+        compatible:
+          contains:
+            const: linaro,scmi-optee
+    then:
+      required:
+        - linaro,optee-channel-id
+
 examples:
   - |
     firmware {
@@ -340,7 +364,48 @@ examples:
                 reg = <0x11>;
                 #power-domain-cells = <1>;
             };
+        };
+    };
 
+  - |
+    firmware {
+        scmi {
+            compatible = "linaro,scmi-optee";
+            linaro,optee-channel-id = <0>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            scmi_dvfs1: protocol@13 {
+                reg = <0x13>;
+                linaro,optee-channel-id = <1>;
+                shmem = <&cpu_optee_lpri0>;
+                #clock-cells = <1>;
+            };
+
+            scmi_clk0: protocol@14 {
+                reg = <0x14>;
+                #clock-cells = <1>;
+            };
+        };
+    };
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        sram@51000000 {
+            compatible = "mmio-sram";
+            reg = <0x0 0x51000000 0x0 0x10000>;
+
+            #address-cells = <1>;
+            #size-cells = <1>;
+            ranges = <0 0x0 0x51000000 0x10000>;
+
+            cpu_optee_lpri0: optee-sram-section@0 {
+                compatible = "arm,scmi-shmem";
+                reg = <0x0 0x80>;
+            };
         };
     };