dt-bindings: timer: renesas: ostm: Convert to json-schema

Convert the Renesas OS Timer (OSTM) Device Tree binding documentation to
json-schema.

Document missing properties.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/timer/renesas,ostm.txt

-* Renesas OS Timer (OSTM)
-
-The OSTM is a multi-channel 32-bit timer/counter with fixed clock
-source that can operate in either interval count down timer or free-running
-compare match mode.
-
-Channels are independent from each other.
-
-Required Properties:
-
-  - compatible: must be one or more of the following:
-    - "renesas,r7s72100-ostm" for the R7S72100 (RZ/A1) OSTM
-    - "renesas,r7s9210-ostm" for the R7S9210 (RZ/A2) OSTM
-    - "renesas,ostm" for any OSTM
-		This is a fallback for the above renesas,*-ostm entries
-
-  - reg: base address and length of the register block for a timer channel.
-
-  - interrupts: interrupt specifier for the timer channel.
-
-  - clocks: clock specifier for the timer channel.
-
-Example: R7S72100 (RZ/A1H) OSTM node
-
-	ostm0: timer@fcfec000 {
-		compatible = "renesas,r7s72100-ostm", "renesas,ostm";
-		reg = <0xfcfec000 0x30>;
-		interrupts = <GIC_SPI 102 IRQ_TYPE_EDGE_RISING>;
-		clocks = <&mstp5_clks R7S72100_CLK_OSTM0>;
-		power-domains = <&cpg_clocks>;
-	};

Documentation/devicetree/bindings/timer/renesas,ostm.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/renesas,ostm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas OS Timer (OSTM)
+
+maintainers:
+  - Chris Brandt <chris.brandt@renesas.com>
+  - Geert Uytterhoeven <geert+renesas@glider.be>
+
+description:
+  The OSTM is a multi-channel 32-bit timer/counter with fixed clock source that
+  can operate in either interval count down timer or free-running compare match
+  mode.
+
+  Channels are independent from each other.
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - renesas,r7s72100-ostm # RZ/A1H
+          - renesas,r7s9210-ostm  # RZ/A2M
+      - const: renesas,ostm       # Generic
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - power-domains
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/r7s72100-clock.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    ostm0: timer@fcfec000 {
+            compatible = "renesas,r7s72100-ostm", "renesas,ostm";
+            reg = <0xfcfec000 0x30>;
+            interrupts = <GIC_SPI 102 IRQ_TYPE_EDGE_RISING>;
+            clocks = <&mstp5_clks R7S72100_CLK_OSTM0>;
+            power-domains = <&cpg_clocks>;
+    };