dt-bindings: power: Add fsl,scu-pd yaml file

In order to replace the fsl,scu txt file from bindings/arm/freescale,
we need to split it between the right subsystems. This patch documents
separately the 'power controller' child node of the SCU main node.
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Signed-off-by: Viorel Suman <viorel.suman@nxp.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt

@@ -62,25 +62,6 @@ i.MX SCU Client Device Node:
 
 Client nodes are maintained as children of the relevant IMX-SCU device node.
 
-Power domain bindings based on SCU Message Protocol
-------------------------------------------------------------
-
-This binding for the SCU power domain providers uses the generic power
-domain binding[2].
-
-Required properties:
-- compatible:		Should be one of:
-			  "fsl,imx8qm-scu-pd",
-			  "fsl,imx8qxp-scu-pd"
-			followed by "fsl,scu-pd"
-
-- #power-domain-cells:	Must be 1. Contains the Resource ID used by
-			SCU commands.
-			See detailed Resource ID list from:
-			include/dt-bindings/firmware/imx/rsrc.h
-
-[2] Documentation/devicetree/bindings/power/power-domain.yaml
-
 RTC bindings based on SCU Message Protocol
 ------------------------------------------------------------
 
@@ -135,11 +116,6 @@ firmware {
 			  &lsio_mu1 1 3
 			  &lsio_mu1 3 3>;
 
-		pd: imx8qx-pd {
-			compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-pd";
-			#power-domain-cells = <1>;
-		};
-
 		rtc: rtc {
 			compatible = "fsl,imx8qxp-sc-rtc";
 		};
@@ -158,5 +134,4 @@ firmware {
 
 serial@5a060000 {
 	...
-	power-domains = <&pd IMX_SC_R_UART_0>;
 };

Documentation/devicetree/bindings/power/fsl,scu-pd.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/fsl,scu-pd.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: i.MX SCU Client Device Node - Power domain bindings based on SCU Message Protocol
+
+maintainers:
+  - Dong Aisheng <aisheng.dong@nxp.com>
+
+description: i.MX SCU Client Device Node
+  Client nodes are maintained as children of the relevant IMX-SCU device node.
+  Power domain bindings based on SCU Message Protocol
+
+allOf:
+  - $ref: power-domain.yaml#
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - fsl,imx8qm-scu-pd
+          - fsl,imx8qxp-scu-pd
+      - const: fsl,scu-pd
+
+  '#power-domain-cells':
+    const: 1
+
+required:
+  - compatible
+  - '#power-domain-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    power-controller {
+        compatible = "fsl,imx8qxp-scu-pd", "fsl,scu-pd";
+        #power-domain-cells = <1>;
+    };