zephyr/machine_wdt: Add watchdog timer implementation.

Simple implementation in-line with the rest of the MicroPython ports

Tested on the nRF52832 and the nRF5340.

Signed-off-by: danicampora <danicampora@gmail.com>

ports/zephyr/machine_wdt.c

@@ -0,0 +1,92 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2025 Daniel Campora on behalf of REMOTE TECH LTD
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// This file is never compiled standalone, it's included directly from
+// extmod/machine_wdt.c via MICROPY_PY_MACHINE_WDT_INCLUDEFILE.
+
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/drivers/watchdog.h>
+#include <zephyr/sys/printk.h>
+#include <stdbool.h>
+
+#include "py/mperrno.h"
+
+typedef struct _machine_wdt_obj_t {
+    mp_obj_base_t base;
+    struct device *wdt;
+    int32_t channel_id;
+} machine_wdt_obj_t;
+
+static machine_wdt_obj_t wdt_default = {
+    {&machine_wdt_type}, NULL, -1
+};
+
+static machine_wdt_obj_t *mp_machine_wdt_make_new_instance(mp_int_t id, mp_int_t timeout_ms) {
+    if (id != 0) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid WDT id"));
+    }
+
+    if (timeout_ms <= 0) {
+        mp_raise_ValueError(MP_ERROR_TEXT("watchdog timeout too short"));
+    }
+
+    wdt_default.wdt = (struct device *)DEVICE_DT_GET(DT_ALIAS(watchdog0));
+
+    if (!device_is_ready(wdt_default.wdt)) {
+        mp_raise_OSError(MP_ENODEV);
+    }
+
+    struct wdt_timeout_cfg wdt_config = {
+        /* Reset SoC when watchdog timer expires. */
+        .flags = WDT_FLAG_RESET_SOC,
+
+        /* Expire watchdog after max window */
+        .window.min = 0,
+        .window.max = timeout_ms,
+    };
+
+    wdt_default.channel_id = wdt_install_timeout(wdt_default.wdt, &wdt_config);
+
+    if (wdt_default.channel_id < 0) {
+        mp_raise_OSError(-wdt_default.channel_id);
+    }
+
+    mp_int_t rs_code = wdt_setup(wdt_default.wdt, WDT_OPT_PAUSE_IN_SLEEP | WDT_OPT_PAUSE_HALTED_BY_DBG);
+
+    if (rs_code < 0) {
+        mp_raise_OSError(-rs_code);
+    }
+
+    return &wdt_default;
+}
+
+static void mp_machine_wdt_feed(machine_wdt_obj_t *self) {
+    mp_int_t rs_code = wdt_feed(self->wdt, self->channel_id);
+    if (rs_code < 0) {
+        mp_raise_OSError(-rs_code);
+    }
+}

ports/zephyr/mpconfigport.h

@@ -68,6 +68,10 @@
 #define MICROPY_PY_MACHINE_PIN_MAKE_NEW mp_pin_make_new
 #define MICROPY_PY_MACHINE_UART     (1)
 #define MICROPY_PY_MACHINE_UART_INCLUDEFILE "ports/zephyr/machine_uart.c"
+#ifdef CONFIG_WATCHDOG
+#define MICROPY_PY_MACHINE_WDT      (1)
+#define MICROPY_PY_MACHINE_WDT_INCLUDEFILE  "ports/zephyr/machine_wdt.c"
+#endif
 #define MICROPY_PY_STRUCT           (0)
 #ifdef CONFIG_NETWORKING
 // If we have networking, we likely want errno comfort

ports/zephyr/prj.conf

@@ -79,3 +79,6 @@ CONFIG_NET_BUF_POOL_USAGE=y
 CONFIG_MICROPY_CONFIGFILE="mpconfigport.h"
 CONFIG_MICROPY_VFS_FAT=y
 CONFIG_MICROPY_VFS_LFS2=y
+
+CONFIG_WATCHDOG=y
+CONFIG_WDT_DISABLE_AT_BOOT=y