FreeRTOS/Demo/CORTEX_EFM32_Pearl_Gecko_Simplicity_Studio/SiLabs_Source/CMSIS/efm32pg1b/system_efm32pg1b.c

/***************************************************************************//**
 * @file system_efm32pg1b.c
 * @brief CMSIS Cortex-M3/M4 System Layer for EFM32 devices.
 * @version 4.2.1
 ******************************************************************************
 * @section License
 * <b>Copyright 2015 Silicon Laboratories, Inc. http://www.silabs.com</b>
 ******************************************************************************
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software.@n
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.@n
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Laboratories, Inc.
 * has no obligation to support this Software. Silicon Laboratories, Inc. is
 * providing the Software "AS IS", with no express or implied warranties of any
 * kind, including, but not limited to, any implied warranties of
 * merchantability or fitness for any particular purpose or warranties against
 * infringement of any proprietary rights of a third party.
 *
 * Silicon Laboratories, Inc. will not be liable for any consequential,
 * incidental, or special damages, or any other relief, or for any claim by
 * any third party, arising from your use of this Software.
 *
 *****************************************************************************/

#include <stdint.h>
#include "em_device.h"

/*******************************************************************************
 ******************************   DEFINES   ************************************
 ******************************************************************************/

/** LFRCO frequency, tuned to below frequency during manufacturing. */
#define EFM32_LFRCO_FREQ  (32768UL)
#define EFM32_ULFRCO_FREQ (1000UL)

/*******************************************************************************
 **************************   LOCAL VARIABLES   ********************************
 ******************************************************************************/

/* System oscillator frequencies. These frequencies are normally constant */
/* for a target, but they are made configurable in order to allow run-time */
/* handling of different boards. The crystal oscillator clocks can be set */
/* compile time to a non-default value by defining respective EFM_nFXO_FREQ */
/* values according to board design. By defining the EFM_nFXO_FREQ to 0, */
/* one indicates that the oscillator is not present, in order to save some */
/* SW footprint. */

#ifndef EFM32_HFRCO_MAX_FREQ
#define EFM32_HFRCO_MAX_FREQ            (38000000UL)
#endif

#ifndef EFM32_HFXO_FREQ
#define EFM32_HFXO_FREQ                 (40000000UL)
#endif

#ifndef EFM32_HFRCO_STARTUP_FREQ
#define EFM32_HFRCO_STARTUP_FREQ        (19000000UL)
#endif


/* Do not define variable if HF crystal oscillator not present */
#if (EFM32_HFXO_FREQ > 0UL)
/** @cond DO_NOT_INCLUDE_WITH_DOXYGEN */
/** System HFXO clock. */
static uint32_t SystemHFXOClock = EFM32_HFXO_FREQ;
/** @endcond (DO_NOT_INCLUDE_WITH_DOXYGEN) */
#endif

#ifndef EFM32_LFXO_FREQ
#define EFM32_LFXO_FREQ (EFM32_LFRCO_FREQ)
#endif
/* Do not define variable if LF crystal oscillator not present */
#if (EFM32_LFXO_FREQ > 0UL)
/** @cond DO_NOT_INCLUDE_WITH_DOXYGEN */
/** System LFXO clock. */
static uint32_t SystemLFXOClock = 32768UL;
/** @endcond (DO_NOT_INCLUDE_WITH_DOXYGEN) */
#endif


/*******************************************************************************
 **************************   GLOBAL VARIABLES   *******************************
 ******************************************************************************/

/**
 * @brief
 *   System System Clock Frequency (Core Clock).
 *
 * @details
 *   Required CMSIS global variable that must be kept up-to-date.
 */
uint32_t SystemCoreClock;


/**
 * @brief
 *   System HFRCO frequency
 *
 * @note
 *   This is an EFM32 proprietary variable, not part of the CMSIS definition.
 *
 * @details
 *   Frequency of the system HFRCO oscillator
 */
uint32_t SystemHfrcoFreq = EFM32_HFRCO_STARTUP_FREQ;


/*******************************************************************************
 **************************   GLOBAL FUNCTIONS   *******************************
 ******************************************************************************/

/***************************************************************************//**
 * @brief
 *   Get the current core clock frequency.
 *
 * @details
 *   Calculate and get the current core clock frequency based on the current
 *   configuration. Assuming that the SystemCoreClock global variable is
 *   maintained, the core clock frequency is stored in that variable as well.
 *   This function will however calculate the core clock based on actual HW
 *   configuration. It will also update the SystemCoreClock global variable.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   The current core clock frequency in Hz.
 ******************************************************************************/
uint32_t SystemCoreClockGet(void)
{
  uint32_t ret;
  uint32_t presc;

  ret   = SystemHFClockGet();
  presc = (CMU->HFCOREPRESC & _CMU_HFCOREPRESC_PRESC_MASK) >>
          _CMU_HFCOREPRESC_PRESC_SHIFT;
  ret  /= (presc + 1);

  /* Keep CMSIS system clock variable up-to-date */
  SystemCoreClock = ret;

  return ret;
}


/***************************************************************************//**
 * @brief
 *   Get the maximum core clock frequency.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   The maximum core clock frequency in Hz.
 ******************************************************************************/
uint32_t SystemMaxCoreClockGet(void)
{
  return (EFM32_HFRCO_MAX_FREQ > EFM32_HFXO_FREQ ? \
          EFM32_HFRCO_MAX_FREQ : EFM32_HFXO_FREQ);
}


/***************************************************************************//**
 * @brief
 *   Get the current HFCLK frequency.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   The current HFCLK frequency in Hz.
 ******************************************************************************/
uint32_t SystemHFClockGet(void)
{
  uint32_t ret;

  switch (CMU->HFCLKSTATUS & _CMU_HFCLKSTATUS_SELECTED_MASK)
  {
    case CMU_HFCLKSTATUS_SELECTED_LFXO:
#if (EFM32_LFXO_FREQ > 0)
      ret = SystemLFXOClock;
#else
      /* We should not get here, since core should not be clocked. May */
      /* be caused by a misconfiguration though. */
      ret = 0;
#endif
      break;

    case CMU_HFCLKSTATUS_SELECTED_LFRCO:
      ret = EFM32_LFRCO_FREQ;
      break;

    case CMU_HFCLKSTATUS_SELECTED_HFXO:
#if (EFM32_HFXO_FREQ > 0)
      ret = SystemHFXOClock;
#else
      /* We should not get here, since core should not be clocked. May */
      /* be caused by a misconfiguration though. */
      ret = 0;
#endif
      break;

    default: /* CMU_HFCLKSTATUS_SELECTED_HFRCO */
      ret = SystemHfrcoFreq;
      break;
  }

  return ret;
}


/**************************************************************************//**
 * @brief
 *   Get high frequency crystal oscillator clock frequency for target system.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   HFXO frequency in Hz.
 *****************************************************************************/
uint32_t SystemHFXOClockGet(void)
{
  /* External crystal oscillator present? */
#if (EFM32_HFXO_FREQ > 0)
  return SystemHFXOClock;
#else
  return 0;
#endif
}


/**************************************************************************//**
 * @brief
 *   Set high frequency crystal oscillator clock frequency for target system.
 *
 * @note
 *   This function is mainly provided for being able to handle target systems
 *   with different HF crystal oscillator frequencies run-time. If used, it
 *   should probably only be used once during system startup.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @param[in] freq
 *   HFXO frequency in Hz used for target.
 *****************************************************************************/
void SystemHFXOClockSet(uint32_t freq)
{
  /* External crystal oscillator present? */
#if (EFM32_HFXO_FREQ > 0)
  SystemHFXOClock = freq;

  /* Update core clock frequency if HFXO is used to clock core */
  if ((CMU->HFCLKSTATUS & _CMU_HFCLKSTATUS_SELECTED_MASK) == CMU_HFCLKSTATUS_SELECTED_HFXO)
  {
    /* The function will update the global variable */
    SystemCoreClockGet();
  }
#else
  (void)freq; /* Unused parameter */
#endif
}


/**************************************************************************//**
 * @brief
 *   Initialize the system.
 *
 * @details
 *   Do required generic HW system init.
 *
 * @note
 *   This function is invoked during system init, before the main() routine
 *   and any data has been initialized. For this reason, it cannot do any
 *   initialization of variables etc.
 *****************************************************************************/
void SystemInit(void)
{
#if (__FPU_PRESENT == 1)
  /* Set floating point coprosessor access mode. */
  SCB->CPACR |= ((3UL << 10 * 2) |      /* set CP10 Full Access */
                 (3UL << 11 * 2));      /* set CP11 Full Access */
#endif
}


/**************************************************************************//**
 * @brief
 *   Get low frequency RC oscillator clock frequency for target system.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   LFRCO frequency in Hz.
 *****************************************************************************/
uint32_t SystemLFRCOClockGet(void)
{
  /* Currently we assume that this frequency is properly tuned during */
  /* manufacturing and is not changed after reset. If future requirements */
  /* for re-tuning by user, we can add support for that. */
  return EFM32_LFRCO_FREQ;
}


/**************************************************************************//**
 * @brief
 *   Get ultra low frequency RC oscillator clock frequency for target system.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   ULFRCO frequency in Hz.
 *****************************************************************************/
uint32_t SystemULFRCOClockGet(void)
{
  /* The ULFRCO frequency is not tuned, and can be very inaccurate */
  return EFM32_ULFRCO_FREQ;
}


/**************************************************************************//**
 * @brief
 *   Get low frequency crystal oscillator clock frequency for target system.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @return
 *   LFXO frequency in Hz.
 *****************************************************************************/
uint32_t SystemLFXOClockGet(void)
{
  /* External crystal oscillator present? */
#if (EFM32_LFXO_FREQ > 0)
  return SystemLFXOClock;
#else
  return 0;
#endif
}


/**************************************************************************//**
 * @brief
 *   Set low frequency crystal oscillator clock frequency for target system.
 *
 * @note
 *   This function is mainly provided for being able to handle target systems
 *   with different HF crystal oscillator frequencies run-time. If used, it
 *   should probably only be used once during system startup.
 *
 * @note
 *   This is an EFM32 proprietary function, not part of the CMSIS definition.
 *
 * @param[in] freq
 *   LFXO frequency in Hz used for target.
 *****************************************************************************/
void SystemLFXOClockSet(uint32_t freq)
{
  /* External crystal oscillator present? */
#if (EFM32_LFXO_FREQ > 0)
  SystemLFXOClock = freq;

  /* Update core clock frequency if LFXO is used to clock core */
  if ((CMU->HFCLKSTATUS & _CMU_HFCLKSTATUS_SELECTED_MASK) == CMU_HFCLKSTATUS_SELECTED_LFXO)
  {
    /* The function will update the global variable */
    SystemCoreClockGet();
  }
#else
  (void)freq; /* Unused parameter */
#endif
}