Merge pull request ARMmbed#14243 from boraozgen/feature/stm32-rtc-hse

STM32: Add HSE support to RTC

Author: 0xc0170

targets/TARGET_STM/mbed_overrides.c

@@ -16,6 +16,7 @@
 #include "cmsis.h"
 #include "objects.h"
 #include "platform/mbed_error.h"
+#include "rtc_api_hal.h"
 
 int mbed_sdk_inited = 0;
 extern void SetSysClock(void);
@@ -285,7 +286,15 @@ void mbed_sdk_init()
 
     /* Start LSI clock for RTC */
 #if DEVICE_RTC
-#if !MBED_CONF_TARGET_LSE_AVAILABLE
+#if (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_HSE)
+    RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
+    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+    PeriphClkInitStruct.RTCClockSelection = (RCC_RTCCLKSOURCE_HSE_DIVX | RTC_HSE_DIV << 16);
+    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
+    {
+        error("PeriphClkInitStruct RTC failed with HSE\n");
+    }
+#elif ((MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_LSE_OR_LSI) && !MBED_CONF_TARGET_LSE_AVAILABLE) || (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_LSI)
     RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 
     if (__HAL_RCC_GET_RTC_SOURCE() != RCC_RTCCLKSOURCE_NO_CLK) {

targets/TARGET_STM/rtc_api.c

@@ -62,7 +62,14 @@ void rtc_init(void)
     while (LL_HSEM_1StepLock(HSEM, CFG_HW_RCC_SEMID)) {
     }
 #endif /* DUAL_CORE */
-#if MBED_CONF_TARGET_LSE_AVAILABLE
+#if (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_HSE)
+    (void)RCC_OscInitStruct;
+    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+    PeriphClkInitStruct.RTCClockSelection = (RCC_RTCCLKSOURCE_HSE_DIVX | RTC_HSE_DIV << 16);
+    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
+        error("PeriphClkInitStruct RTC failed with HSE\n");
+    }
+#elif (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_LSE_OR_LSI) && MBED_CONF_TARGET_LSE_AVAILABLE
     RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE;
     RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE;
 #if MBED_CONF_TARGET_LSE_BYPASS
@@ -82,7 +89,7 @@ void rtc_init(void)
     if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
         error("PeriphClkInitStruct RTC failed with LSE\n");
     }
-#else /*  MBED_CONF_TARGET_LSE_AVAILABLE */
+#else /* Fallback to LSI */
 #if TARGET_STM32WB
     RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI1;
 #else
@@ -101,7 +108,7 @@ void rtc_init(void)
     if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
         error("PeriphClkInitStruct RTC failed with LSI\n");
     }
-#endif /* MBED_CONF_TARGET_LSE_AVAILABLE */
+#endif /* MBED_CONF_TARGET_RTC_CLOCK_SOURCE */
 #if defined(DUAL_CORE) && (TARGET_STM32H7)
     LL_HSEM_ReleaseLock(HSEM, CFG_HW_RCC_SEMID, HSEM_CR_COREID_CURRENT);
 #endif /* DUAL_CORE */

targets/TARGET_STM/rtc_api_hal.h

@@ -38,7 +38,26 @@
 extern "C" {
 #endif
 
-#if MBED_CONF_TARGET_LSE_AVAILABLE
+// Possible choices of the RTC_CLOCK_SOURCE configuration set in json file
+#define USE_RTC_CLK_LSE_OR_LSI 1
+#define USE_RTC_CLK_LSI 2
+#define USE_RTC_CLK_HSE 3
+
+#if !((MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_LSE_OR_LSI) || (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_LSI) || (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_HSE))
+#error "RTC clock configuration is invalid!"
+#endif
+
+#if (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_HSE) && !(TARGET_STM32F2 || TARGET_STM32F3 || TARGET_STM32F4)
+#error "RTC from HSE not supported for this target"
+#endif
+
+#if (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_HSE)
+#define RTC_CLOCK 1000000U
+#define RTC_HSE_DIV (HSE_VALUE / RTC_CLOCK)
+#if RTC_HSE_DIV > 31
+#error "HSE value too high for RTC"
+#endif
+#elif (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_LSE_OR_LSI) && MBED_CONF_TARGET_LSE_AVAILABLE
 #define RTC_CLOCK LSE_VALUE
 #else
 #define RTC_CLOCK LSI_VALUE
@@ -47,7 +66,11 @@ extern "C" {
 #if DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM
 /* PREDIV_A : 7-bit asynchronous prescaler */
 /* PREDIV_A is set to set LPTICKER frequency to RTC_CLOCK/4 */
+#if (MBED_CONF_TARGET_RTC_CLOCK_SOURCE == USE_RTC_CLK_HSE)
+#define PREDIV_A_VALUE 124
+#else
 #define PREDIV_A_VALUE 3
+#endif
 
 /** Read RTC counter with sub second precision
  *

targets/targets.json

@@ -1220,6 +1220,10 @@
                 "help": "Define if a Low Speed External xtal (LSE) is available on the board (0 = No, 1 = Yes). If Yes, the LSE will be used to clock the RTC, LPUART, ... otherwise the Low Speed Internal clock (LSI) will be used",
                 "value": "1"
             },
+            "rtc_clock_source": {
+                "help": "Define the RTC clock source. USE_RTC_CLK_LSE_OR_LSI, USE_RTC_CLK_LSI, USE_RTC_CLK_HSE. LPTICKER is not available for HSE and should be removed from the target configuration.",
+                "value": "USE_RTC_CLK_LSE_OR_LSI"
+            },
             "lpuart_clock_source": {
                 "help": "Define the LPUART clock source. Mask values: USE_LPUART_CLK_LSE, USE_LPUART_CLK_PCLK1, USE_LPUART_CLK_HSI",
                 "value": "USE_LPUART_CLK_LSE|USE_LPUART_CLK_PCLK1"