mbed-os/targets/TARGET_STM/rtc_api.c

/* mbed Microcontroller Library
 *******************************************************************************
 * Copyright (c) 2018, STMicroelectronics
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
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 *    this list of conditions and the following disclaimer in the documentation
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 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 *******************************************************************************
 */

#if DEVICE_RTC

#include "rtc_api_hal.h"
#include "mbed_mktime.h"
#include "mbed_error.h"
#include "mbed_critical.h"

#if DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM
volatile uint32_t LPTICKER_counter = 0;
volatile uint32_t LPTICKER_RTC_time = 0;
#endif

static int RTC_inited = 0;

static RTC_HandleTypeDef RtcHandle;

void rtc_init(void)
{
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};
    RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};

    if (RTC_inited) {
        return;
    }
    RTC_inited = 1;

    // Enable access to Backup domain
    __HAL_RCC_PWR_CLK_ENABLE();
    HAL_PWR_EnableBkUpAccess();

#if MBED_CONF_TARGET_LSE_AVAILABLE
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE;
    RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE;
    RCC_OscInitStruct.LSEState       = RCC_LSE_ON;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        error("Cannot initialize RTC with LSE\n");
    }

    __HAL_RCC_RTC_CONFIG(RCC_RTCCLKSOURCE_LSE);

    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
    PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
        error("PeriphClkInitStruct RTC failed with LSE\n");
    }
#else /*  MBED_CONF_TARGET_LSE_AVAILABLE */
#if TARGET_STM32WB
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI1;
#else
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI;
#endif
    RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE;
    RCC_OscInitStruct.LSIState       = RCC_LSI_ON;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        error("Cannot initialize RTC with LSI\n");
    }

    __HAL_RCC_RTC_CONFIG(RCC_RTCCLKSOURCE_LSI);

    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
    PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
        error("PeriphClkInitStruct RTC failed with LSI\n");
    }
#endif /* MBED_CONF_TARGET_LSE_AVAILABLE */

    // Enable RTC
    __HAL_RCC_RTC_ENABLE();

#if defined __HAL_RCC_RTCAPB_CLK_ENABLE /* part of STM32L4 */
    __HAL_RCC_RTCAPB_CLK_ENABLE();
#endif /* __HAL_RCC_RTCAPB_CLK_ENABLE */

    RtcHandle.Instance = RTC;
    RtcHandle.State = HAL_RTC_STATE_RESET;

#if TARGET_STM32F1
    RtcHandle.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
#else /* TARGET_STM32F1 */
    RtcHandle.Init.HourFormat     = RTC_HOURFORMAT_24;
    RtcHandle.Init.AsynchPrediv   = PREDIV_A_VALUE;
    RtcHandle.Init.SynchPrediv    = PREDIV_S_VALUE;
    RtcHandle.Init.OutPut         = RTC_OUTPUT_DISABLE;
    RtcHandle.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
    RtcHandle.Init.OutPutType     = RTC_OUTPUT_TYPE_OPENDRAIN;
#if defined (RTC_OUTPUT_REMAP_NONE)
    RtcHandle.Init.OutPutRemap    = RTC_OUTPUT_REMAP_NONE;
#endif /* defined (RTC_OUTPUT_REMAP_NONE) */
#if defined (RTC_OUTPUT_PULLUP_NONE)
    RtcHandle.Init.OutPutPullUp   = RTC_OUTPUT_PULLUP_NONE;
#endif /* defined (RTC_OUTPUT_PULLUP_NONE) */
#endif /* TARGET_STM32F1 */

    if (HAL_RTC_Init(&RtcHandle) != HAL_OK) {
        error("RTC initialization failed\n");
    }

#if !(TARGET_STM32F1) && !(TARGET_STM32F2)
    /* STM32F1 : there are no shadow registers */
    /* STM32F2 : shadow registers can not be bypassed */
    if (HAL_RTCEx_EnableBypassShadow(&RtcHandle) != HAL_OK) {
        error("EnableBypassShadow error\n");
    }
#endif /* TARGET_STM32F1 || TARGET_STM32F2 */
}

void rtc_free(void)
{
    /* RTC clock can not be reset */
}


/*
Information about STM32F0, STM32F2, STM32F3, STM32F4, STM32F7, STM32L0, STM32L1, STM32L4:
BCD format is used to store the date in the RTC. The year is store on 2 * 4 bits.
Because the first year is reserved to see if the RTC is init, the supposed range is 01-99.
1st point is to cover the standard range from 1970 to 2038 (limited by the 32 bits of time_t).
2nd point is to keep the year 1970 and the leap years synchronized.

So by moving it 68 years forward from 1970, it become 1969-2067 which include 1970-2038.
68 is also a multiple of 4 so it let the leap year synchronized.

Information about STM32F1:
32bit register is used (no BCD format) for the seconds.
For date, there is no specific register, only a software structure.
It is then not a problem to not use shifts.
*/
time_t rtc_read(void)
{
#if TARGET_STM32F1

    RtcHandle.Instance = RTC;
    return RTC_ReadTimeCounter(&RtcHandle);

#else /* TARGET_STM32F1 */

    struct tm timeinfo;

    /* Since the shadow registers are bypassed we have to read the time twice and compare them until both times are the same */
    uint32_t Read_time = RTC->TR & RTC_TR_RESERVED_MASK;
    uint32_t Read_date = RTC->DR & RTC_DR_RESERVED_MASK;

    while ((Read_time != (RTC->TR & RTC_TR_RESERVED_MASK)) || (Read_date != (RTC->DR & RTC_DR_RESERVED_MASK))) {
        Read_time = RTC->TR & RTC_TR_RESERVED_MASK;
        Read_date = RTC->DR & RTC_DR_RESERVED_MASK;
    }

    /* Setup a tm structure based on the RTC
    struct tm :
        tm_sec      seconds after the minute 0-61
        tm_min      minutes after the hour 0-59
        tm_hour     hours since midnight 0-23
        tm_mday     day of the month 1-31
        tm_mon      months since January 0-11
        tm_year     years since 1900
        tm_yday     information is ignored by _rtc_maketime
        tm_wday     information is ignored by _rtc_maketime
        tm_isdst    information is ignored by _rtc_maketime
    */
    timeinfo.tm_mday = RTC_Bcd2ToByte((uint8_t)(Read_date & (RTC_DR_DT | RTC_DR_DU)));
    timeinfo.tm_mon  = RTC_Bcd2ToByte((uint8_t)((Read_date & (RTC_DR_MT | RTC_DR_MU))  >> 8)) - 1;
    timeinfo.tm_year = RTC_Bcd2ToByte((uint8_t)((Read_date & (RTC_DR_YT | RTC_DR_YU))  >> 16)) + 68;
    timeinfo.tm_hour = RTC_Bcd2ToByte((uint8_t)((Read_time & (RTC_TR_HT  | RTC_TR_HU))  >> 16));
    timeinfo.tm_min  = RTC_Bcd2ToByte((uint8_t)((Read_time & (RTC_TR_MNT | RTC_TR_MNU)) >> 8));
    timeinfo.tm_sec  = RTC_Bcd2ToByte((uint8_t)((Read_time & (RTC_TR_ST  | RTC_TR_SU))  >> 0));

    // Convert to timestamp
    time_t t;
    if (_rtc_maketime(&timeinfo, &t, RTC_4_YEAR_LEAP_YEAR_SUPPORT) == false) {
        return 0;
    }

    return t;

#endif /* TARGET_STM32F1 */
}



void rtc_write(time_t t)
{
#if TARGET_STM32F1

    RtcHandle.Instance = RTC;
    if (RTC_WriteTimeCounter(&RtcHandle, t) != HAL_OK) {
        error("RTC_WriteTimeCounter error\n");
    }

#else /* TARGET_STM32F1 */

    RTC_DateTypeDef dateStruct = {0};
    RTC_TimeTypeDef timeStruct = {0};

    core_util_critical_section_enter();
    RtcHandle.Instance = RTC;

    // Convert the time into a tm
    struct tm timeinfo;
    if (_rtc_localtime(t, &timeinfo, RTC_4_YEAR_LEAP_YEAR_SUPPORT) == false) {
        return;
    }

    // Fill RTC structures
    if (timeinfo.tm_wday == 0) { /* Sunday specific case */
        dateStruct.WeekDay    = RTC_WEEKDAY_SUNDAY;
    } else {
        dateStruct.WeekDay    = timeinfo.tm_wday;
    }
    dateStruct.Month          = timeinfo.tm_mon + 1;
    dateStruct.Date           = timeinfo.tm_mday;
    dateStruct.Year           = timeinfo.tm_year - 68;
    timeStruct.Hours          = timeinfo.tm_hour;
    timeStruct.Minutes        = timeinfo.tm_min;
    timeStruct.Seconds        = timeinfo.tm_sec;
    timeStruct.TimeFormat     = RTC_HOURFORMAT_24;
    timeStruct.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
    timeStruct.StoreOperation = RTC_STOREOPERATION_RESET;

#if DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM
    /* Before setting the new time, we need to update the LPTICKER_counter value */
    /* rtc_read_lp function is then called */
    rtc_read_lp();

    /* In rtc_read_lp, LPTICKER_RTC_time value has been updated with the current time */
    /* We need now to overwrite the value with the new RTC time */
    /* Note that when a new RTC time is set by HW, the RTC SubSeconds counter is reset to PREDIV_S_VALUE */
    LPTICKER_RTC_time = (timeStruct.Seconds + timeStruct.Minutes * 60 + timeStruct.Hours * 60 * 60) * PREDIV_S_VALUE;
#endif /* DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM */

    // Change the RTC current date/time
    if (HAL_RTC_SetDate(&RtcHandle, &dateStruct, RTC_FORMAT_BIN) != HAL_OK) {
        error("HAL_RTC_SetDate error\n");
    }
    if (HAL_RTC_SetTime(&RtcHandle, &timeStruct, RTC_FORMAT_BIN) != HAL_OK) {
        error("HAL_RTC_SetTime error\n");
    }

    core_util_critical_section_exit();
#endif /* TARGET_STM32F1 */
}

int rtc_isenabled(void)
{
#if defined (RTC_FLAG_INITS) /* all STM32 except STM32F1 */
    return LL_RTC_IsActiveFlag_INITS(RTC);
#else /* RTC_FLAG_INITS */ /* TARGET_STM32F1 */
    return ((RTC->CRL & RTC_CRL_RSF) ==  RTC_CRL_RSF);
#endif /* RTC_FLAG_INITS */
}


#if DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM

static void RTC_IRQHandler(void);
static void (*irq_handler)(void);

volatile uint8_t lp_Fired = 0;

static void RTC_IRQHandler(void)
{
    /*  Update HAL state */
    RtcHandle.Instance = RTC;
    if (__HAL_RTC_WAKEUPTIMER_GET_IT(&RtcHandle, RTC_IT_WUT)) {
        /* Get the status of the Interrupt */
        if ((uint32_t)(RTC->CR & RTC_IT_WUT) != (uint32_t)RESET) {
            /* Clear the WAKEUPTIMER interrupt pending bit */
            __HAL_RTC_WAKEUPTIMER_CLEAR_FLAG(&RtcHandle, RTC_FLAG_WUTF);

            lp_Fired = 0;
            if (irq_handler) {
                irq_handler();
            }
        }
    }

    if (lp_Fired) {
        lp_Fired = 0;
        if (irq_handler) {
            irq_handler();
        }
    }

#ifdef __HAL_RTC_WAKEUPTIMER_EXTI_CLEAR_FLAG
    __HAL_RTC_WAKEUPTIMER_EXTI_CLEAR_FLAG();
#endif
}

uint32_t rtc_read_lp(void)
{
    /* RTC_time_tick is the addition of the RTC time register (in second) and the RTC sub-second register
    *  This time value is breaking each 24h (= 86400s = 0x15180)
    *  In order to get a U32 continuous time information, we use an internal counter : LPTICKER_counter
    *  This counter is the addition of each spent time since last function call
    *  Current RTC time is saved into LPTICKER_RTC_time
    *  NB: rtc_read_lp() output is not the time in us, but the LPTICKER_counter (frequency LSE/4 = 8kHz => 122us)
    */
    core_util_critical_section_enter();
    struct tm timeinfo;

    /* Since the shadow registers are bypassed we have to read the time twice and compare them until both times are the same */
    /* We don't have to read date as we bypass shadow registers */
    uint32_t Read_time = (uint32_t)(RTC->TR & RTC_TR_RESERVED_MASK);
    uint32_t Read_SubSeconds = (uint32_t)(RTC->SSR);

    while ((Read_time != (RTC->TR & RTC_TR_RESERVED_MASK)) || (Read_SubSeconds != (RTC->SSR))) {
        Read_time = (uint32_t)(RTC->TR & RTC_TR_RESERVED_MASK);
        Read_SubSeconds = (uint32_t)(RTC->SSR);
    }

    timeinfo.tm_hour = RTC_Bcd2ToByte((uint8_t)((Read_time & (RTC_TR_HT  | RTC_TR_HU))  >> 16));
    timeinfo.tm_min  = RTC_Bcd2ToByte((uint8_t)((Read_time & (RTC_TR_MNT | RTC_TR_MNU)) >> 8));
    timeinfo.tm_sec  = RTC_Bcd2ToByte((uint8_t)((Read_time & (RTC_TR_ST  | RTC_TR_SU))  >> 0));

    uint32_t RTC_time_tick = (timeinfo.tm_sec + timeinfo.tm_min * 60 + timeinfo.tm_hour * 60 * 60) * PREDIV_S_VALUE + PREDIV_S_VALUE - Read_SubSeconds; // Max 0x0001-517F * 8191 + 8191 = 0x2A2E-AE80

    if (LPTICKER_RTC_time <= RTC_time_tick) {
        LPTICKER_counter += (RTC_time_tick - LPTICKER_RTC_time);
    } else {
        /* When RTC time is 0h00.01 and was 11H59.59, difference is "current time + 24h - previous time" */
        LPTICKER_counter += (RTC_time_tick + 24 * 60 * 60 * PREDIV_S_VALUE - LPTICKER_RTC_time);
    }
    LPTICKER_RTC_time = RTC_time_tick;

    core_util_critical_section_exit();
    return LPTICKER_counter;
}

void rtc_set_wake_up_timer(timestamp_t timestamp)
{
    /* RTC periodic auto wake up timer is used
    *  This WakeUpTimer is loaded to an init value => WakeUpCounter
    *  then timer starts counting down (even in low-power modes)
    *  When it reaches 0, the WUTF flag is set in the RTC_ISR register
    */
    uint32_t WakeUpCounter;
    uint32_t WakeUpClock = RTC_WAKEUPCLOCK_RTCCLK_DIV4;

    core_util_critical_section_enter();

    /* MBED API gives the timestamp value to set
    *  WakeUpCounter is then the delta between timestamp and the current tick (LPTICKER_counter)
    *  If the current tick preceeds timestamp value, max U32 is added
    */
    uint32_t current_lp_time = rtc_read_lp();
    if (timestamp < current_lp_time) {
        WakeUpCounter = 0xFFFFFFFF - current_lp_time + timestamp;
    } else {
        WakeUpCounter = timestamp - current_lp_time;
    }

    /* RTC WakeUpCounter is 16 bits
    *  Corresponding time value depends on WakeUpClock
    *  - RTC clock divided by 4  : max WakeUpCounter value is  8s (precision around 122 us)
    *  - RTC clock divided by 8  : max WakeUpCounter value is 16s (precision around 244 us)
    *  - RTC clock divided by 16 : max WakeUpCounter value is 32s (precision around 488 us)
    *  - 1 Hz internal clock 16b : max WakeUpCounter value is 18h (precision 1 s)
    *  - 1 Hz internal clock 17b : max WakeUpCounter value is 36h (precision 1 s)
    */
    if (WakeUpCounter > 0xFFFF) {
        WakeUpClock = RTC_WAKEUPCLOCK_RTCCLK_DIV8;
        WakeUpCounter = WakeUpCounter / 2;

        if (WakeUpCounter > 0xFFFF) {
            WakeUpClock = RTC_WAKEUPCLOCK_RTCCLK_DIV16;
            WakeUpCounter = WakeUpCounter / 2;

            if (WakeUpCounter > 0xFFFF) {
                /* Tick value needs to be translated in seconds : TICK * 16 (previous div16 value) / RTC clock (32768) */
                WakeUpClock = RTC_WAKEUPCLOCK_CK_SPRE_16BITS;
                WakeUpCounter = WakeUpCounter / 2048;

                if (WakeUpCounter > 0xFFFF) {
                    /* In this case 2^16 is added to the 16-bit counter value */
                    WakeUpClock = RTC_WAKEUPCLOCK_CK_SPRE_17BITS;
                    WakeUpCounter = WakeUpCounter - 0x10000;
                }
            }
        }
    }

    RtcHandle.Instance = RTC;
    HAL_RTCEx_DeactivateWakeUpTimer(&RtcHandle);
    if (HAL_RTCEx_SetWakeUpTimer_IT(&RtcHandle, WakeUpCounter, WakeUpClock) != HAL_OK) {
        error("rtc_set_wake_up_timer init error\n");
    }

    NVIC_SetVector(RTC_WKUP_IRQn, (uint32_t)RTC_IRQHandler);
    irq_handler = (void (*)(void))lp_ticker_irq_handler;
    NVIC_EnableIRQ(RTC_WKUP_IRQn);
    core_util_critical_section_exit();
}

void rtc_fire_interrupt(void)
{
    lp_Fired = 1;
    NVIC_SetVector(RTC_WKUP_IRQn, (uint32_t)RTC_IRQHandler);
    irq_handler = (void (*)(void))lp_ticker_irq_handler;
    NVIC_SetPendingIRQ(RTC_WKUP_IRQn);
    NVIC_EnableIRQ(RTC_WKUP_IRQn);
}

void rtc_deactivate_wake_up_timer(void)
{
    RtcHandle.Instance = RTC;
    HAL_RTCEx_DeactivateWakeUpTimer(&RtcHandle);
    NVIC_DisableIRQ(RTC_WKUP_IRQn);
}

#endif /* DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM */

#endif /* DEVICE_RTC */