Add RTC module to ports/analog for MAX32690_apard

I added a port-specific module, RTC to ports/analog. Now the analog port is capable of
handling `rtc.set_time_source()`, `rtc.RTC()` and `r.datetime()`. Note that the RTC
calibration functions are not implemented and is planned for near future.

The implementation in the RTC module also enables two functions in the time module,
which are `time.time()` and `time.localtime()`.

The following example prints the current time every second:

import time
import rtc

r = rtc.RTC)
r.datetime = time.struct_Time((2000, 1, 1, 1, 1, 1, 0, -1, -1))

while(True):
    current_time = r.datetime
    print(current_time)
    time.sleep(1)

Files I modified:
* ports/analog/common-hal/rtc/RTC.c
* ports/analog/common-hal/rtc/RTC.h
* ports/analog/common-hal/rtc/__init__.c
* ports/analog/mpconfigport.mk

Author: PaggieZ

ports/analog/common-hal/rtc/RTC.c

@@ -0,0 +1,42 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2019 Nick Moore for Adafruit Industries
+// SPDX-FileCopyrightText: Copyright (c) 2019 Artur Pacholec
+// SPDX-FileCopyrightText: Copyright (c) 2025 Peggy Zhu, Analog Devices, Inc.
+//
+// SPDX-License-Identifier: MIT
+
+#include <stdlib.h>
+
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "shared/timeutils/timeutils.h"
+#include "supervisor/port.h"
+
+// This is the time in seconds since 2000 that the RTC was started.
+// TODO: Change the offset to ticks so that it can be a subsecond adjustment.
+static uint32_t rtc_offset = 0;
+
+void common_hal_rtc_get_time(timeutils_struct_time_t *tm) {
+    uint64_t ticks_s = port_get_raw_ticks(NULL) / 1024;
+    timeutils_seconds_since_2000_to_struct_time(rtc_offset + ticks_s, tm);
+}
+
+void common_hal_rtc_set_time(timeutils_struct_time_t *tm) {
+    uint64_t ticks_s = port_get_raw_ticks(NULL) / 1024;
+    uint32_t epoch_s = timeutils_seconds_since_2000(
+        tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec
+        );
+    rtc_offset = epoch_s - ticks_s;
+}
+
+// the calibration function will be implemented in near future
+// the RTC oscillator on my MAX32690-APARD is only off by 0.001 second
+// the inaccuracy is still tolerable
+int common_hal_rtc_get_calibration(void) {
+    return 0;
+}
+
+void common_hal_rtc_set_calibration(int calibration) {
+    mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_calibration);
+}

ports/analog/common-hal/rtc/RTC.h

@@ -0,0 +1,11 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2018 Noralf Trønnes
+// SPDX-FileCopyrightText: Copyright (c) 2019 Artur Pacholec
+// SPDX-FileCopyrightText: Copyright (c) 2025 Peggy Zhu, Analog Devices, Inc.
+//
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+extern void rtc_reset(void);

ports/analog/common-hal/rtc/__init__.c

@@ -0,0 +1,6 @@
+// This file is part of the CircuitPython project: https://circuitpython.org
+//
+// SPDX-FileCopyrightText: Copyright (c) 2024 Adafruit Industries LLC
+// SPDX-FileCopyrightText: Copyright (c) 2025 Peggy Zhu, Analog Devices, Inc.
+//
+// SPDX-License-Identifier: MIT

ports/analog/mpconfigport.mk

@@ -24,7 +24,7 @@ INTERNAL_FLASH_FILESYSTEM = 1
 
 # Plan to implement
 CIRCUITPY_BUSIO ?= 0
-CIRCUITPY_RTC ?= 0
+CIRCUITPY_RTC ?= 1
 
 # Other modules (may or may not implement):
 CIRCUITPY_ANALOGIO ?= 0