dt-bindings: clock: Convert pwm-clock to DT schema

Convert the pwm-clock binding to DT schema format. A straight-forward
conversion.

Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221011162919.3025038-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/clock/pwm-clock.txt

@@ -1,26 +0,0 @@
-Binding for an external clock signal driven by a PWM pin.
-
-This binding uses the common clock binding[1] and the common PWM binding[2].
-
-[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
-[2] Documentation/devicetree/bindings/pwm/pwm.txt
-
-Required properties:
-- compatible : shall be "pwm-clock".
-- #clock-cells : from common clock binding; shall be set to 0.
-- pwms : from common PWM binding; this determines the clock frequency
-  via the period given in the PWM specifier.
-
-Optional properties:
-- clock-output-names : From common clock binding.
-- clock-frequency : Exact output frequency, in case the PWM period
-  is not exact but was rounded to nanoseconds.
-
-Example:
-	clock {
-		compatible = "pwm-clock";
-		#clock-cells = <0>;
-		clock-frequency = <25000000>;
-		clock-output-names = "mipi_mclk";
-		pwms = <&pwm2 0 40>; /* 1 / 40 ns = 25 MHz */
-	};

Documentation/devicetree/bindings/clock/pwm-clock.yaml

@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/pwm-clock.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: An external clock signal driven by a PWM pin.
+
+maintainers:
+  - Philipp Zabel <p.zabel@pengutronix.de>
+
+properties:
+  compatible:
+    const: pwm-clock
+
+  '#clock-cells':
+    const: 0
+
+  clock-frequency:
+    description: Exact output frequency, in case the PWM period is not exact
+      but was rounded to nanoseconds.
+
+  clock-output-names:
+    maxItems: 1
+
+  pwms:
+    maxItems: 1
+
+required:
+  - compatible
+  - '#clock-cells'
+  - pwms
+
+additionalProperties: false
+
+examples:
+  - |
+    clock {
+        compatible = "pwm-clock";
+        #clock-cells = <0>;
+        clock-frequency = <25000000>;
+        clock-output-names = "mipi_mclk";
+        pwms = <&pwm2 0 40>; /* 1 / 40 ns = 25 MHz */
+    };
+...