dt-bindings: rtc: Convert rtc-cmos binding to YAML

Convert the rtc-cmos devicetree bindings to dt schema.

The original text binding documents only the motorola,mc146818
compatible. Existing in-tree Devicetree sources also use the
intel,ce4100-rtc compatible together with the motorola,mc146818
fallback, but this was not documented. Document the Intel variant in the
schema so that these existing configurations are accepted during schema
validation.

Signed-off-by: Teja Sai Charan Bellamkonda <tejaasaye@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260709221944.159244-1-tejaasaye@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/rtc/rtc-cmos.txt

@@ -1,27 +0,0 @@
- Motorola mc146818 compatible RTC
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Required properties:
-  - compatible : "motorola,mc146818"
-  - reg : should contain registers location and length.
-
-Optional properties:
-  - interrupts : should contain interrupt.
-  - ctrl-reg : Contains the initial value of the control register also
-    called "Register B".
-  - freq-reg : Contains the initial value of the frequency register also
-    called "Register A".
-
-"Register A" and "B" are usually initialized by the firmware (BIOS for
-instance). If this is not done, it can be performed by the driver.
-
-ISA Example:
-
-	rtc@70 {
-	         compatible = "motorola,mc146818";
-	         interrupts = <8 3>;
-	         interrupt-parent = <&ioapic1>;
-	         ctrl-reg = <2>;
-	         freq-reg = <0x26>;
-	         reg = <1 0x70 2>;
-	 };

Documentation/devicetree/bindings/rtc/rtc-cmos.yaml

@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/rtc-cmos.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Motorola mc146818 compatible RTC
+
+maintainers:
+  - Alexandre Belloni <alexandre.belloni@bootlin.com>
+
+properties:
+  compatible:
+    oneOf:
+      - const: motorola,mc146818
+
+      - items:
+          - const: intel,ce4100-rtc
+          - const: motorola,mc146818
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  ctrl-reg:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Initial value of the control register
+      (also known as Register B).
+
+  freq-reg:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Initial value of the frequency register
+      (also known as Register A).
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - $ref: rtc.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    bus {
+        #address-cells = <2>;
+        #size-cells = <1>;
+
+        rtc@1,70 {
+            compatible = "motorola,mc146818";
+            reg = <0x1 0x70 0x2>;
+
+            interrupts = <8 3>;
+
+            ctrl-reg = <2>;
+            freq-reg = <0x26>;
+        };
+    };