tinySA/os/hal/platforms/STM32/RTCv1/rtc_lld.c

/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    STM32/rtc_lld.c
 * @brief   STM32 RTC subsystem low level driver header.
 *
 * @addtogroup RTC
 * @{
 */

#include "ch.h"
#include "hal.h"


#if HAL_USE_RTC || defined(__DOXYGEN__)

/*===========================================================================*/
/* Driver exported variables.                                                */
/*===========================================================================*/

/** @brief RTC driver identifier.*/
RTCDriver RTCD;


/*===========================================================================*/
/* Driver local variables.                                                   */
/*===========================================================================*/

/*===========================================================================*/
/* Driver local functions.                                                   */
/*===========================================================================*/

/**
 * @brief   Shared IRQ handler.
 *
 * @param[in] rtcp    pointer to a @p RTCDriver object
 *
 * @notapi
 */
#if RTC_SUPPORTS_CALLBACKS

static void rtc_lld_serve_interrupt(RTCDriver *rtcp){
  chSysLockFromIsr();

  if ((RTC->CRH & RTC_CRH_SECIE) && \
      (RTC->CRL & RTC_CRL_SECF) && \
      (rtcp->second_cb != NULL)){
    rtcp->second_cb(rtcp);
    RTC->CRL &= ~RTC_CRL_SECF;
  }
  if ((RTC->CRH & RTC_CRH_ALRIE) && \
      (RTC->CRL & RTC_CRL_ALRF) && \
      (rtcp->alarm_cb != NULL)){
    rtcp->alarm_cb(rtcp);
    RTC->CRL &= ~RTC_CRL_ALRF;
  }
  if ((RTC->CRH & RTC_CRH_OWIE) && \
      (RTC->CRL & RTC_CRL_OWF) && \
      (rtcp->overflow_cb != NULL)){
    rtcp->overflow_cb(rtcp);
    RTC->CRL &= ~RTC_CRL_OWF;
  }

  chSysUnlockFromIsr();
}
#endif /* RTC_SUPPORTS_CALLBACKS */

/*===========================================================================*/
/* Driver interrupt handlers.                                                */
/*===========================================================================*/

/**
 * @brief   RTC interrupt handler.
 * @isr
 */
#if RTC_SUPPORTS_CALLBACKS

CH_IRQ_HANDLER(RTC_IRQHandler) {
  CH_IRQ_PROLOGUE();
  rtc_lld_serve_interrupt(&RTCD);
  CH_IRQ_EPILOGUE();
}

#endif /* RTC_SUPPORTS_CALLBACKS */

/*===========================================================================*/
/* Driver exported functions.                                                */
/*===========================================================================*/

/**
 * @brief   Enable access to registers and initialize RTC if BKP domain
 *          was previously reseted.
 *
 * @note:   Cold start time of LSE oscillator on STM32 platform 
 *          takes about 3 seconds.
 *
 * @notapi
 */
void rtc_lld_init(void){
  uint32_t preload = 0;

  rccEnableBKPInterface(FALSE);

  /* enable access to BKP registers */
  PWR->CR |= PWR_CR_DBP;
  /* select clock source */
  RCC->BDCR |= STM32_RTC;

#if STM32_RTC == STM32_RTC_LSE
    if (! ((RCC->BDCR & RCC_BDCR_RTCEN) || (RCC->BDCR & RCC_BDCR_LSEON))){
      RCC->BDCR |= RCC_BDCR_LSEON; 
      while(!(RCC->BDCR & RCC_BDCR_LSERDY))
        ;
      RCC->BDCR |= RCC_BDCR_RTCEN;
    }
    preload = STM32_LSECLK - 1;

#elif STM32_RTC == STM32_RTC_LSI
    RCC->CSR  |= RCC_CSR_LSION;
    while(!(RCC->CSR & RCC_CSR_LSIRDY))
      ;
    /* According to errata sheet we must wait additional 100 uS for stabilization */
    uint32_t tmo = (STM32_SYSCLK / 1000000 ) * 100;
    while(tmo--)
      ;
    RCC->BDCR |= RCC_BDCR_RTCEN;
    preload = STM32_LSICLK - 1;

#elif STM32_RTC == STM32_RTC_HSE
    preload = (STM32_HSICLK / 128) - 1;

#else
#error "RTC clock source not selected"
#endif

  /* Ensure that RTC_CNT and RTC_DIV contain actual values after enabling
   * clocking on APB1, because these values only update when APB1 functioning.*/
  RTC->CRL &= ~(RTC_CRL_RSF);
  while (!(RTC->CRL & RTC_CRL_RSF))
    ;

  /* Write preload register only if its value changed */
  if (preload != ((((uint32_t)(RTC->PRLH)) << 16) + RTC->PRLL)){
    while(!(RTC->CRL & RTC_CRL_RTOFF))
      ;

    RTC->CRL |= RTC_CRL_CNF;                            /* switch on configure mode */
    RTC->PRLH = (uint16_t)((preload >> 16) & 0b1111);   /* write preloader */
    RTC->PRLL = (uint16_t)(preload & 0xFFFF);
    RTC->CRL &= ~RTC_CRL_CNF;                           /* switch off configure mode */

    while(!(RTC->CRL & RTC_CRL_RTOFF))                  /* wait for completion */
      ;
  }

  /* disable all interrupts and clear all even flags just to be safe */
  RTC->CRH &= ~(RTC_CRH_OWIE | RTC_CRH_ALRIE | RTC_CRH_SECIE);
  RTC->CRL &= ~(RTC_CRL_SECF | RTC_CRL_ALRF  | RTC_CRL_OWF);

#if RTC_SUPPORTS_CALLBACKS
  RTCD.alarm_cb    = NULL;
  RTCD.overflow_cb = NULL;
  RTCD.second_cb   = NULL;
#endif /* RTC_SUPPORTS_CALLBACKS */
}

/**
 * @brief     Enables and disables callbacks on the fly.
 *
 * @details   Pass callback function(s) in argument(s) to enable callback(s).
 *            Pass NULL to disable callback.
 *
 * @pre       To use this function you must set @p RTC_SUPPORTS_CALLBACKS
 *            to @p TRUE.
 *
 * @param[in] rtcp         pointer to RTC driver structure.
 * @param[in] overflowcb   overflow callback function.
 * @param[in] secondcb     every second callback function.
 * @param[in] alarmcb      alarm callback function.
 *
 * @notapi
 */
#if RTC_SUPPORTS_CALLBACKS
void rtc_lld_set_callback(RTCDriver *rtcp, rtccb_t overflowcb,
                          rtccb_t secondcb, rtccb_t alarmcb){

  uint16_t isr_flags = 0;

  if (overflowcb != NULL){
    rtcp->overflow_cb = *overflowcb;
    isr_flags |= RTC_CRH_OWIE;
  }
  else{
    rtcp->overflow_cb = NULL;
    isr_flags &= ~RTC_CRH_OWIE;
  }

  if (alarmcb != NULL){
    rtcp->alarm_cb = *alarmcb;
    isr_flags |= RTC_CRH_ALRIE;
  }
  else{
    rtcp->alarm_cb = NULL;
    isr_flags &= ~RTC_CRH_ALRIE;
  }

  if (secondcb != NULL){
    rtcp->second_cb = *secondcb;
    isr_flags |= RTC_CRH_SECIE;
  }
  else{
    rtcp->second_cb = NULL;
    isr_flags &= ~RTC_CRH_SECIE;
  }

  if(isr_flags != 0){
    NVICEnableVector(RTC_IRQn, CORTEX_PRIORITY_MASK(STM32_RTC_IRQ_PRIORITY));
    RTC->CRH |= isr_flags;
  }
  else{
    NVICDisableVector(RTC_IRQn);
    RTC->CRH = 0;
  }
}
#endif /* RTC_SUPPORTS_CALLBACKS */

/**
 * @brief     Set current time.
 *
 * @param[in] timespec     pointer to variable storing time.
 *
 * @note      Fractional part will be silently ignored. There is no possibility
 *            to change it on STM32F1xx platform.
 * @notapi
 */
void rtc_lld_set_time(RTCDateTime *timespec){

  while(!(RTC->CRL & RTC_CRL_RTOFF))
    ;

  RTC->CRL |= RTC_CRL_CNF;                            /* switch on configure mode */
  RTC->CNTH = (uint16_t)((timespec->tv_sec >> 16) & 0xFFFF);
  RTC->CNTL = (uint16_t)(timespec->tv_sec & 0xFFFF);
  RTC->CRL &= ~RTC_CRL_CNF;                           /* switch off configure mode */

  while(!(RTC->CRL & RTC_CRL_RTOFF))                  /* wait for completion */
    ;
}

/**
 * @brief     Get current time.
 *
 * @param[in] msec     pointer to variable for storing fractional part of
 *                     time (milliseconds).
 *
 * @notapi
 */
inline void rtc_lld_get_time(RTCDateTime *timespec){
  uint32_t time_frac = 0;
  time_frac = (((uint32_t)RTC->DIVH) << 16) + (RTC->DIVL);

  timespec->tv_msec = (uint16_t)(((STM32_LSECLK - time_frac) * 1000) / STM32_LSECLK);
  timespec->tv_sec = (RTC->CNTH << 16) + RTC->CNTL;
}

/**
 * @brief     Set alarm time.
 *
 * @param[in] timespec     pointer to variable storing time of alarm.
 *
 * @note      Fractional part will be silently ignored. There is no possibility
 *            to change it on STM32F1xx platform.
 *
 * @note      Default value after BKP domain reset is 0xFFFFFFFF
 *
 * @notapi
 */
void rtc_lld_set_alarm(RTCDateTime *timespec){

  while(!(RTC->CRL & RTC_CRL_RTOFF))
    ;

  RTC->CRL |= RTC_CRL_CNF;                            /* switch on configure mode */
  RTC->ALRH = (uint16_t)((timespec->tv_sec >> 16) & 0xFFFF);
  RTC->ALRL = (uint16_t)(timespec->tv_sec & 0xFFFF);
  RTC->CRL &= ~RTC_CRL_CNF;                           /* switch off configure mode */

#if !(RTC_SUPPORTS_CALLBACKS)
  RTC->CRL &= ~RTC_CRL_ALRF;
  RTC->CRH |= RTC_CRH_ALRIE;
#endif /* !(RTC_SUPPORTS_CALLBACKS) */

  while(!(RTC->CRL & RTC_CRL_RTOFF))                  /* wait for completion */
    ;
}

/**
 * @brief Get current alarm time.
 *
 * @param[in] timespec     pointer to variable storing time of alarm.
 *
 * @note      Fractional part will be silently ignored. There is no possibility
 *            to change it on STM32F1xx platform.
 *
 * @note      Default value after BKP domain reset is 0xFFFFFFFF
 *
 * @notapi
 */
inline void rtc_lld_get_alarm(RTCDateTime *timespec){
  timespec->tv_sec = ((RTC->ALRH << 16) + RTC->ALRL);
}


#endif /* HAL_USE_RTC */

/** @} */