WDT: Add support for XTAL32K Watchdog timer

components/esp_system/include/esp_xt_wdt.h

@@ -0,0 +1,63 @@
+/*
+ * SPDX-FileCopyrightText: 2021 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include "esp_err.h"
+#include "esp_intr_alloc.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief esp_xt_wdt configuration struct
+ *
+ */
+typedef struct {
+    uint8_t timeout;                /*!< Watchdog timeout */
+    bool auto_backup_clk_enable;    /*!< Enable automatic switch to backup clock at timeout */
+} esp_xt_wdt_config_t;
+
+/*  Callback function for WDT interrupt*/
+typedef void (*esp_xt_callback_t)(void *arg);
+
+/**
+ * @brief Initializes the xtal32k watchdog timer
+ *
+ * @param cfg Pointer to configuration struct
+ * @return esp_err_t
+ *      - ESP_OK: XTWDT was successfully enabled
+ *      - ESP_ERR_NO_MEM: Failed to allocate ISR
+ */
+esp_err_t esp_xt_wdt_init(const esp_xt_wdt_config_t *cfg);
+
+/**
+ * @brief Register a callback function that will be called when the watchdog
+ *        times out.
+ *
+ * @note This function will be called from an interrupt context where the cache might be disabled.
+ *       Thus the function should be placed in IRAM and must not perform any blocking operations.
+ *
+ *       Only one callback function can be registered, any call to esp_xt_wdt_register_callback
+ *       will override the previous callback function.
+ *
+ * @param func The callback function to register
+ * @param arg  Pointer to argument that will be passed to the callback function
+ */
+void esp_xt_wdt_register_callback(esp_xt_callback_t func, void *arg);
+
+/**
+ * @brief Restores the xtal32k clock and re-enables the WDT
+ *
+ */
+void esp_xt_wdt_restore_clk(void);
+
+#ifdef __cplusplus
+}
+#endif