stm32 ticker: change th eplace where timer init in done, fix overflow issue with 16-bit timer

- Move back the 16/32bit timer initialization in HAL_InitTick() and not in us_ticker_init()
- Use ticker_read_us() and us_ticker_read() in HAL_GetTick() to fix potential overflow issue with the 16bit timer

==> These corrections allow timer, rtc, sleep, tick tests to PASS

targets/TARGET_STM/hal_tick_overrides.c

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2013 ARM Limited
+ * Copyright (c) 2006-2018 ARM Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,18 +14,58 @@
  * limitations under the License.
  */
 #include "hal/us_ticker_api.h"
+#include "us_ticker_data.h"
+
+// This variable is set to 1 at the of mbed_sdk_init function.
+// The ticker_read_us function must not be called until the mbed_sdk_init is terminated.
+extern int mbed_sdk_inited;
+
+// Defined in us_ticker.c
+void init_16bit_timer(void);
+void init_32bit_timer(void);
+
+#if TIM_MST_BIT_WIDTH == 16
+// Variables also reset in us_ticker_init()
+uint32_t prev_time = 0;
+uint32_t elapsed_time = 0;
+#endif
 
 // Overwrite default HAL functions defined as "weak"
 
 HAL_StatusTypeDef HAL_InitTick(uint32_t TickPriority)
 {
-    us_ticker_init();
+#if TIM_MST_BIT_WIDTH == 16
+    init_16bit_timer();
+#else
+    init_32bit_timer();
+#endif
     return HAL_OK;
 }
 
 uint32_t HAL_GetTick()
 {
-    return 0;
+#if TIM_MST_BIT_WIDTH == 16
+    uint32_t new_time;
+    if (mbed_sdk_inited) {
+        // Apply the latest time recorded just before the sdk is inited
+        new_time = ticker_read_us(get_us_ticker_data()) + prev_time;
+        prev_time = 0; // Use this time only once
+        return (new_time / 1000);
+    }
+    else {
+        new_time = us_ticker_read();
+        elapsed_time += (new_time - prev_time) & 0xFFFF; // Only use the lower 16 bits
+        prev_time = new_time;
+        return (elapsed_time / 1000);
+    }
+#else // 32-bit timer
+    if (mbed_sdk_inited) {
+        return (ticker_read_us(get_us_ticker_data()) / 1000);
+    }
+    else {
+        return (us_ticker_read() / 1000);
+    }
+#endif
 }
 
 void HAL_SuspendTick(void)

targets/TARGET_STM/us_ticker.c

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2016 ARM Limited
+ * Copyright (c) 2006-2018 ARM Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,9 @@
 
 TIM_HandleTypeDef TimMasterHandle;
 
-bool us_ticker_initialized = false;
+uint32_t timer_cnt_reg;
+uint32_t timer_ccr1_reg;
+uint32_t timer_dier_reg;
 
 const ticker_info_t *us_ticker_get_info()
 {
@@ -36,6 +38,9 @@ void us_ticker_irq_handler(void);
 // ************************************ 16-bit timer ************************************
 #if TIM_MST_BIT_WIDTH == 16
 
+extern uint32_t prev_time;
+extern uint32_t elapsed_time;
+
 #if defined(TARGET_STM32F0)
 void timer_update_irq_handler(void)
 {
@@ -60,32 +65,8 @@ void timer_oc_irq_handler(void)
     }
 }
 
-// ************************************ 32-bit timer ************************************
-#else
-
-void timer_irq_handler(void)
+void init_16bit_timer(void)
 {
-    TimMasterHandle.Instance = TIM_MST;
-    if (__HAL_TIM_GET_FLAG(&TimMasterHandle, TIM_FLAG_CC1) == SET) {
-        if (__HAL_TIM_GET_IT_SOURCE(&TimMasterHandle, TIM_IT_CC1) == SET) {
-            __HAL_TIM_CLEAR_IT(&TimMasterHandle, TIM_IT_CC1);
-            us_ticker_irq_handler();
-        }
-    }
-}
-
-#endif // 16-bit/32-bit timer
-
-void us_ticker_init(void)
-{
-    if (us_ticker_initialized) {
-        __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
-        __HAL_TIM_CLEAR_FLAG(&TimMasterHandle, TIM_FLAG_CC1);
-        return;
-    }
-
-// ************************************ 16-bit timer ************************************
-#if TIM_MST_BIT_WIDTH == 16
     // Enable timer clock
     TIM_MST_RCC;
 
@@ -137,9 +118,27 @@ void us_ticker_init(void)
 
     __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
 
+    // Used by HAL_GetTick()
+    prev_time = 0;
+    elapsed_time = 0;
+}
+
 // ************************************ 32-bit timer ************************************
 #else
 
+void timer_irq_handler(void)
+{
+    TimMasterHandle.Instance = TIM_MST;
+    if (__HAL_TIM_GET_FLAG(&TimMasterHandle, TIM_FLAG_CC1) == SET) {
+        if (__HAL_TIM_GET_IT_SOURCE(&TimMasterHandle, TIM_IT_CC1) == SET) {
+            __HAL_TIM_CLEAR_IT(&TimMasterHandle, TIM_IT_CC1);
+            us_ticker_irq_handler();
+        }
+    }
+}
+
+void init_32bit_timer(void)
+{
     RCC_ClkInitTypeDef RCC_ClkInitStruct;
     uint32_t PclkFreq;
 
@@ -162,8 +161,8 @@ void us_ticker_init(void)
     TIM_MST_RESET_OFF;
 
     // Configure time base
-    TimMasterHandle.Instance = TIM_MST;
-    TimMasterHandle.Init.Period          = 0xFFFFFFFF;
+    TimMasterHandle.Instance    = TIM_MST;
+    TimMasterHandle.Init.Period = 0xFFFFFFFF;
 
     // TIMxCLK = PCLKx when the APB prescaler = 1 else TIMxCLK = 2 * PCLKx
 #if TIM_MST_PCLK == 1
@@ -199,11 +198,14 @@ void us_ticker_init(void)
 #endif
 
     __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
+}
 
 #endif // 16-bit/32-bit timer
 
-    us_ticker_initialized = true;
-
+void us_ticker_init(void)
+{
+    // Timer is already initialized in HAL_InitTick()
+    __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
 }
 
 uint32_t us_ticker_read()
@@ -241,10 +243,6 @@ void us_ticker_clear_interrupt(void)
     __HAL_TIM_CLEAR_FLAG(&TimMasterHandle, TIM_FLAG_CC1);
 }
 
-uint32_t timer_cnt_reg;
-uint32_t timer_ccr1_reg;
-uint32_t timer_dier_reg;
-
 void save_timer_ctx(void)
 {
     timer_cnt_reg = __HAL_TIM_GET_COUNTER(&TimMasterHandle);