esp_timer: add a function to get next alarm time

components/esp32/esp_timer.c

@@ -455,6 +455,18 @@ esp_err_t esp_timer_dump(FILE* stream)
     return ESP_OK;
 }
 
+int64_t IRAM_ATTR esp_timer_get_next_alarm()
+{
+    int64_t next_alarm = INT64_MAX;
+    timer_list_lock();
+    esp_timer_handle_t it = LIST_FIRST(&s_timers);
+    if (it) {
+        next_alarm = it->alarm;
+    }
+    timer_list_unlock();
+    return next_alarm;
+}
+
 int64_t IRAM_ATTR esp_timer_get_time()
 {
     return (int64_t) esp_timer_impl_get_time();

components/esp32/include/esp_timer.h

@@ -189,6 +189,13 @@ esp_err_t esp_timer_delete(esp_timer_handle_t timer);
  */
 int64_t esp_timer_get_time();
 
+/**
+ * @brief Get the timestamp when the next timeout is expected to occur
+ * @return Timestamp of the nearest timer event, in microseconds.
+ *         The timebase is the same as for the values returned by esp_timer_get_time.
+ */
+int64_t esp_timer_get_next_alarm();
+
 /**
  * @brief Dump the list of timers to a stream
  *