IDF release/v4.4 ddc44956bf (#5911)

esp-dsp: master 6b25cbb
esp-face: master 859f32a
esp-rainmaker: f1b82c7
esp32-camera: master 61400bc
esp_littlefs: master 3c29afc

tools/sdk/esp32s2/include/esp_timer/include/esp_timer.h

@@ -1,16 +1,8 @@
-// Copyright 2017 Espressif Systems (Shanghai) PTE LTD
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
+/*
+ * SPDX-FileCopyrightText: 2017-2021 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
 
 #pragma once
 
@@ -83,11 +75,28 @@ typedef struct {
     bool skip_unhandled_events;     //!< Skip unhandled events for periodic timers
 } esp_timer_create_args_t;
 
+
+/**
+ * @brief Minimal initialization of esp_timer
+ *
+ * @note This function is called from startup code. Applications do not need
+ * to call this function before using other esp_timer APIs.
+ *
+ * This function can be called very early in startup process, after this call
+ * only esp_timer_get_time function can be used.
+ *
+ * @return
+ *      - ESP_OK on success
+ */
+esp_err_t esp_timer_early_init(void);
+
 /**
  * @brief Initialize esp_timer library
  *
  * @note This function is called from startup code. Applications do not need
  * to call this function before using other esp_timer APIs.
+ * Before calling this function, esp_timer_early_init must be called by the
+ * startup code.
  *
  * @return
  *      - ESP_OK on success