drivers: rtc: add rtc support for apollo510

This commit adds support for apollo510 rtc

Signed-off-by: Hao Luo <hluo@ambiq.com>

Author: AlessandroLuo

boards/ambiq/apollo510_evb/apollo510_evb.dts

@@ -89,6 +89,11 @@
 	pinctrl-names = "default";
 };
 
+&rtc0 {
+	status = "disabled";
+	clock = "XTAL";
+};
+
 &uart0 {
 	current-speed = <115200>;
 	pinctrl-0 = <&uart0_default>;

boards/ambiq/apollo510_evb/apollo510_evb.yaml

@@ -11,6 +11,7 @@ supported:
   - uart
   - watchdog
   - gpio
+  - rtc
   - clock_control
   - mspi
 testing:

dts/arm/ambiq/ambiq_apollo510.dtsi

@@ -149,6 +149,14 @@
 			status = "okay";
 		};
 
+		rtc0: rtc@RTC_BASE_NAME {
+			compatible = "ambiq,rtc";
+			reg = <RTC_REG_BASE RTC_REG_SIZE>;
+			interrupts = <2 0>;
+			alarms-count = <1>;
+			status = "disabled";
+		};
+
 		wdt0: watchdog@WDT_BASE_NAME {
 			compatible = "ambiq,watchdog";
 			reg = <WDT_REG_BASE WDT_REG_SIZE>;

samples/drivers/rtc/boards/apollo510_evb.overlay

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2025 Ambiq Micro Inc. <www.ambiq.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		rtc = &rtc0;
+	};
+};
+
+&rtc0 {
+	status = "okay";
+};

tests/drivers/rtc/rtc_api/boards/apollo510_evb.conf

@@ -0,0 +1,5 @@
+# Copyright (c) 2025, Ambiq Micro Inc. <www.ambiq.com>
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_RTC_ALARM=y
+CONFIG_TEST_RTC_ALARM_TIME_MASK=79

tests/drivers/rtc/rtc_api/boards/apollo510_evb.overlay

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2025 Ambiq Micro Inc. <www.ambiq.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		rtc = &rtc0;
+	};
+};
+
+&rtc0 {
+	status = "okay";
+};