dt-bindings: rtc: rzn1: Describe the RZN1 RTC

Add new binding file for this RTC.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220516082504.33913-2-miquel.raynal@bootlin.com

Documentation/devicetree/bindings/rtc/renesas,rzn1-rtc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/renesas,rzn1-rtc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas RZ/N1 SoCs Real-Time Clock DT bindings
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+allOf:
+  - $ref: rtc.yaml#
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - renesas,r9a06g032-rtc
+      - const: renesas,rzn1-rtc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    minItems: 3
+    maxItems: 3
+
+  interrupt-names:
+    items:
+      - const: alarm
+      - const: timer
+      - const: pps
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: hclk
+
+  power-domains:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - interrupt-names
+  - clocks
+  - clock-names
+  - power-domains
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/r9a06g032-sysctrl.h>
+    rtc@40006000 {
+       compatible = "renesas,r9a06g032-rtc", "renesas,rzn1-rtc";
+       reg = <0x40006000 0x1000>;
+       interrupts = <GIC_SPI 66 IRQ_TYPE_EDGE_RISING>,
+                    <GIC_SPI 67 IRQ_TYPE_EDGE_RISING>,
+                    <GIC_SPI 68 IRQ_TYPE_EDGE_RISING>;
+       interrupt-names = "alarm", "timer", "pps";
+       clocks = <&sysctrl R9A06G032_HCLK_RTC>;
+       clock-names = "hclk";
+       power-domains = <&sysctrl>;
+       start-year = <2000>;
+     };