feat(bod): Add a simple callback function for brownout detector,

Closes https://github.com/espressif/esp-idf/pull/15661

components/esp_hw_support/power_supply/brownout.c

@@ -26,6 +26,9 @@
 #include "esp_rom_uart.h"
 #include "hal/uart_ll.h"
 #include "soc/power_supply_periph.h"
+#include "esp_brownout.h"
+#include "esp_check.h"
+#include "esp_memory_utils.h"
 
 #if defined(CONFIG_ESP_BROWNOUT_DET_LVL)
 #define BROWNOUT_DET_LVL CONFIG_ESP_BROWNOUT_DET_LVL
@@ -35,6 +38,8 @@
 
 static __attribute__((unused)) DRAM_ATTR const char TAG[] = "BOD";
 
+static brownout_callback_t s_brownout_callback = NULL;
+
 #if CONFIG_ESP_BROWNOUT_USE_INTR
 IRAM_ATTR static void rtc_brownout_isr_handler(void *arg)
 {
@@ -44,6 +49,10 @@ IRAM_ATTR static void rtc_brownout_isr_handler(void *arg)
      */
     brownout_ll_intr_clear();
 
+    if (s_brownout_callback) {
+        s_brownout_callback();
+    }
+
     // Stop the other core.
 #if !CONFIG_ESP_SYSTEM_SINGLE_CORE_MODE
     const uint32_t core_id = esp_cpu_get_core_id();
@@ -123,3 +132,13 @@ void esp_brownout_disable(void)
     rtc_isr_deregister(rtc_brownout_isr_handler, NULL);
 #endif // CONFIG_ESP_BROWNOUT_USE_INTR
 }
+
+esp_err_t esp_brownout_register_callback(brownout_callback_t callback)
+{
+    if (callback != NULL) {
+        ESP_RETURN_ON_FALSE(esp_ptr_in_iram(callback), ESP_ERR_INVALID_ARG, TAG, "brownout callback is not in IRAM");
+    }
+    s_brownout_callback = callback;
+
+    return ESP_OK;
+}

components/esp_hw_support/power_supply/include/esp_brownout.h

@@ -0,0 +1,37 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+ #pragma once
+
+ #include "esp_err.h"
+
+ #ifdef __cplusplus
+ extern "C" {
+ #endif
+
+/**
+ * @brief Type definition for a brownout callback function.
+ *
+ * This type defines a callback function that will be invoked when a brownout
+ * condition is detected.
+ *
+ * @note The callback function is executed in an brownout interrupt context, so it
+ *       must be designed to execute quickly and must not call blocking functions.
+ */
+typedef void (*brownout_callback_t)(void);
+
+/**
+ * @brief Register a callback to be called during brownout interrupt.
+ *
+ * @note The callback in brownout must be put in IRAM.
+ *
+ * @param callback The callback function to register. Set NULL to unregister the callback.
+ */
+esp_err_t esp_brownout_register_callback(brownout_callback_t callback);
+
+#ifdef __cplusplus
+}
+#endif