dt-bindings: bus: simple-pm-bus: convert bindings to json-schema

Convert Simple Power-Managed Bus bindings documentation to json-schema.

As a side effect of this change only simple-pm-bus is used in example. A
follow-up patch will provide an example for the separately documented
Renesas Bus State Controller (BSC) that uses "renesas,bsc-sh73a0" and
"renesas,bsc" compat strings.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/bus/simple-pm-bus.txt

-Simple Power-Managed Bus
-========================
-
-A Simple Power-Managed Bus is a transparent bus that doesn't need a real
-driver, as it's typically initialized by the boot loader.
-
-However, its bus controller is part of a PM domain, or under the control of a
-functional clock.  Hence, the bus controller's PM domain and/or clock must be
-enabled for child devices connected to the bus (either on-SoC or externally)
-to function.
-
-While "simple-pm-bus" follows the "simple-bus" set of properties, as specified
-in the Devicetree Specification, it is not an extension of "simple-bus".
-
-
-Required properties:
-  - compatible: Must contain at least "simple-pm-bus".
-		Must not contain "simple-bus".
-		It's recommended to let this be preceded by one or more
-		vendor-specific compatible values.
-  - #address-cells, #size-cells, ranges: Must describe the mapping between
-		parent address and child address spaces.
-
-Optional platform-specific properties for clock or PM domain control (at least
-one of them is required):
-  - clocks: Must contain a reference to the functional clock(s),
-  - power-domains: Must contain a reference to the PM domain.
-Please refer to the binding documentation for the clock and/or PM domain
-providers for more details.
-
-
-Example:
-
-	bsc: bus@fec10000 {
-		compatible = "renesas,bsc-sh73a0", "renesas,bsc",
-			     "simple-pm-bus";
-		#address-cells = <1>;
-		#size-cells = <1>;
-		ranges = <0 0 0x20000000>;
-		reg = <0xfec10000 0x400>;
-		interrupts = <0 39 IRQ_TYPE_LEVEL_HIGH>;
-		clocks = <&zb_clk>;
-		power-domains = <&pd_a4s>;
-	};

Documentation/devicetree/bindings/bus/simple-pm-bus.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/simple-pm-bus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Simple Power-Managed Bus
+
+maintainers:
+  - Geert Uytterhoeven <geert+renesas@glider.be>
+
+description: |
+  A Simple Power-Managed Bus is a transparent bus that doesn't need a real
+  driver, as it's typically initialized by the boot loader.
+
+  However, its bus controller is part of a PM domain, or under the control
+  of a functional clock.  Hence, the bus controller's PM domain and/or
+  clock must be enabled for child devices connected to the bus (either
+  on-SoC or externally) to function.
+
+  While "simple-pm-bus" follows the "simple-bus" set of properties, as
+  specified in the Devicetree Specification, it is not an extension of
+  "simple-bus".
+
+properties:
+  $nodename:
+    pattern: "^bus(@[0-9a-f]+)?$"
+
+  compatible:
+    contains:
+      const: simple-pm-bus
+    description:
+      Shall contain "simple-pm-bus" in addition to a optional bus-specific
+      compatible strings defined in individual pm-bus bindings.
+
+  '#address-cells':
+    enum: [ 1, 2 ]
+
+  '#size-cells':
+    enum: [ 1, 2 ]
+
+  ranges: true
+
+  clocks: true
+    # Functional clocks
+    # Required if power-domains is absent, optional otherwise
+
+  power-domains:
+    # Required if clocks is absent, optional otherwise
+    minItems: 1
+
+required:
+  - compatible
+  - '#address-cells'
+  - '#size-cells'
+  - ranges
+
+anyOf:
+  - required:
+      - clocks
+  - required:
+      - power-domains
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,gcc-msm8996.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    bus {
+        power-domains = <&gcc AGGRE0_NOC_GDSC>;
+        compatible = "simple-pm-bus";
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges;
+    };