dt-bindings: rtc: Convert Broadcom STB waketimer to YAML

Convert the Broadcom STB waketimer Device Tree binding to YAML to help
with validation.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20211208003727.3596577-5-f.fainelli@gmail.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/rtc/brcm,brcmstb-waketimer.txt

-Broadcom STB wake-up Timer
-
-The Broadcom STB wake-up timer provides a 27Mhz resolution timer, with the
-ability to wake up the system from low-power suspend/standby modes.
-
-Required properties:
-- compatible     : should contain "brcm,brcmstb-waketimer"
-- reg            : the register start and length for the WKTMR block
-- interrupts     : The TIMER interrupt
-- clocks	 : The phandle to the UPG fixed clock (27Mhz domain)
-
-Example:
-
-waketimer@f0411580 {
-	compatible = "brcm,brcmstb-waketimer";
-	reg = <0xf0411580 0x14>;
-	interrupts = <0x3>;
-	interrupt-parent = <&aon_pm_l2_intc>;
-	clocks = <&upg_fixed>;
-};

Documentation/devicetree/bindings/rtc/brcm,brcmstb-waketimer.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/brcm,brcmstb-waketimer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom STB wake-up Timer
+
+maintainers:
+  - Florian Fainelli <f.fainelli@gmail.com>
+
+description:
+  The Broadcom STB wake-up timer provides a 27Mhz resolution timer, with the
+  ability to wake up the system from low-power suspend/standby modes.
+
+allOf:
+  - $ref: "rtc.yaml#"
+
+properties:
+  compatible:
+    const: brcm,brcmstb-waketimer
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description: the TIMER interrupt
+    maxItems: 1
+
+  clocks:
+    description: clock reference in the 27MHz domain
+    maxItems: 1
+
+additionalProperties: false
+
+examples:
+  - |
+    rtc@f0411580 {
+        compatible = "brcm,brcmstb-waketimer";
+        reg = <0xf0411580 0x14>;
+        interrupts = <0x3>;
+        interrupt-parent = <&aon_pm_l2_intc>;
+        clocks = <&upg_fixed>;
+    };