From 74de5a7c5890b39ee128b11ffd8c5ece2a8daf81 Mon Sep 17 00:00:00 2001
From: Renz Bagaporo <renz.bagaporo@espressif.com>
Date: Mon, 8 Mar 2021 23:01:40 +0800
Subject: [PATCH] esp_timer: correct startup time

---
 components/esp_timer/CMakeLists.txt           |  3 +-
 .../private_include/esp_timer_impl.h          |  7 +++
 components/esp_timer/src/esp_timer.c          | 18 +------
 components/esp_timer/src/system_time.c        | 53 +++++++++++++++++++
 4 files changed, 63 insertions(+), 18 deletions(-)
 create mode 100644 components/esp_timer/src/system_time.c

diff --git a/components/esp_timer/CMakeLists.txt b/components/esp_timer/CMakeLists.txt
index 0fbbee530b..d799aa7c23 100644
--- a/components/esp_timer/CMakeLists.txt
+++ b/components/esp_timer/CMakeLists.txt
@@ -1,7 +1,8 @@
 idf_build_get_property(target IDF_TARGET)
 
 set(srcs "src/esp_timer.c"
-         "src/ets_timer_legacy.c")
+         "src/ets_timer_legacy.c"
+         "src/system_time.c")
 
 if(CONFIG_ESP_TIMER_IMPL_FRC2)
     list(APPEND srcs "src/esp_timer_impl_frc_legacy.c")
diff --git a/components/esp_timer/private_include/esp_timer_impl.h b/components/esp_timer/private_include/esp_timer_impl.h
index d572550ad8..63daba0d9e 100644
--- a/components/esp_timer/private_include/esp_timer_impl.h
+++ b/components/esp_timer/private_include/esp_timer_impl.h
@@ -132,3 +132,10 @@ uint64_t esp_timer_impl_get_counter_reg(void);
  * @return the value of the alarm register
  */
 uint64_t esp_timer_impl_get_alarm_reg(void);
+
+#if CONFIG_ESP_TIME_FUNCS_USE_ESP_TIMER
+/**
+ * @brief Initialize esp_timer as system time provider.
+ */
+void esp_timer_impl_init_system_time(void);
+#endif
diff --git a/components/esp_timer/src/esp_timer.c b/components/esp_timer/src/esp_timer.c
index 81d8c00161..8e370a8604 100644
--- a/components/esp_timer/src/esp_timer.c
+++ b/components/esp_timer/src/esp_timer.c
@@ -446,9 +446,7 @@ esp_err_t esp_timer_init(void)
     }
 
 #if CONFIG_ESP_TIME_FUNCS_USE_ESP_TIMER
-    // [refactor-todo] this logic, "esp_rtc_get_time_us() - g_startup_time", is also
-    // the weak definition of esp_system_get_time; find a way to remove this duplication.
-    esp_timer_private_advance(esp_rtc_get_time_us() - g_startup_time);
+    esp_timer_impl_init_system_time();
 #endif
 
     return ESP_OK;
@@ -600,17 +598,3 @@ int64_t IRAM_ATTR esp_timer_get_next_alarm(void)
     }
     return next_alarm;
 }
-
-// Provides strong definition for system time functions relied upon
-// by core components.
-#if CONFIG_ESP_TIME_FUNCS_USE_ESP_TIMER
-int64_t IRAM_ATTR esp_system_get_time(void)
-{
-    return esp_timer_get_time();
-}
-
-uint32_t IRAM_ATTR esp_system_get_time_resolution(void)
-{
-    return 1000;
-}
-#endif
diff --git a/components/esp_timer/src/system_time.c b/components/esp_timer/src/system_time.c
new file mode 100644
index 0000000000..08f0e7d292
--- /dev/null
+++ b/components/esp_timer/src/system_time.c
@@ -0,0 +1,53 @@
+// 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.
+
+// Provides strong definition for system time functions relied upon
+// by core components.
+#include "sdkconfig.h"
+
+#if CONFIG_ESP_TIME_FUNCS_USE_ESP_TIMER
+#include "esp_timer.h"
+#include "esp_timer_impl.h"
+
+#include "esp_private/startup_internal.h"
+
+#if CONFIG_IDF_TARGET_ESP32
+#include "esp32/rtc.h"
+#elif CONFIG_IDF_TARGET_ESP32S2
+#include "esp32s2/rtc.h"
+#elif CONFIG_IDF_TARGET_ESP32S3
+#include "esp32s3/rtc.h"
+#elif CONFIG_IDF_TARGET_ESP32C3
+#include "esp32c3/rtc.h"
+#endif
+
+// Correction for underlying timer to keep definition
+// of system time consistent.
+static int64_t s_correction_us = 0;
+
+void esp_timer_impl_init_system_time(void)
+{
+    s_correction_us = esp_rtc_get_time_us() - g_startup_time - esp_timer_impl_get_time();
+}
+
+int64_t IRAM_ATTR esp_system_get_time(void)
+{
+    return esp_timer_get_time() + s_correction_us;
+}
+
+uint32_t IRAM_ATTR esp_system_get_time_resolution(void)
+{
+    return 1000;
+}
+#endif