File content as of revision 189:f392fc9709a3:

/**
  ******************************************************************************
  * @file    system_stm32f2xx.c
  * @author  MCD Application Team
  * @version V2.2.0
  * @date    17-March-2017
  * @brief   CMSIS Cortex-M3 Device Peripheral Access Layer System Source File.
  *             
  *   This file provides two functions and one global variable to be called from 
  *   user application:
  *      - SystemInit(): This function is called at startup just after reset and 
  *                      before branch to main program. This call is made inside
  *                      the "startup_stm32f2xx.s" file.
  *
  *      - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
  *                                  by the user application to setup the SysTick 
  *                                  timer or configure other parameters.
  *                                     
  *      - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
  *                                 be called whenever the core clock is changed
  *                                 during program execution.
  *
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2016 STMicroelectronics</center></h2>
  *
  * 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.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      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
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */

/** @addtogroup CMSIS
  * @{
  */

/** @addtogroup stm32f2xx_system
  * @{
  */  
  
/** @addtogroup STM32F2xx_System_Private_Includes
  * @{
  */

#include "stm32f2xx.h"

#if !defined  (HSE_VALUE) 
  #define HSE_VALUE    ((uint32_t)25000000) /*!< Default value of the External oscillator in Hz */
#endif /* HSE_VALUE */

#if !defined  (HSI_VALUE)
  #define HSI_VALUE    ((uint32_t)16000000) /*!< Value of the Internal oscillator in Hz*/
#endif /* HSI_VALUE */

/**
  * @}
  */

/** @addtogroup STM32F2xx_System_Private_TypesDefinitions
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F2xx_System_Private_Defines
  * @{
  */
/************************* Miscellaneous Configuration ************************/
/*!< Uncomment the following line if you need to use external SRAM mounted
     on STM322xG_EVAL board as data memory  */
/* #define DATA_IN_ExtSRAM */

/*!< Uncomment the following line if you need to relocate your vector Table in
     Internal SRAM. */
/* #define VECT_TAB_SRAM */
#define VECT_TAB_OFFSET  0x00 /*!< Vector Table base offset field. 
                                   This value must be a multiple of 0x200. */
/******************************************************************************/

/**
  * @}
  */

/** @addtogroup STM32F2xx_System_Private_Macros
  * @{
  */

/**
  * @}
  */

/** @addtogroup STM32F2xx_System_Private_Variables
  * @{
  */
  
  /* This variable can be updated in Three ways :
      1) by calling CMSIS function SystemCoreClockUpdate()
      2) by calling HAL API function HAL_RCC_GetHCLKFreq()
      3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency 
         Note: If you use this function to configure the system clock; then there
               is no need to call the 2 first functions listed above, since SystemCoreClock
               variable is updated automatically.
  */
  uint32_t SystemCoreClock = 16000000;
  const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
  const uint8_t APBPrescTable[8]  = {0, 0, 0, 0, 1, 2, 3, 4};
/**
  * @}
  */

/** @addtogroup STM32F2xx_System_Private_FunctionPrototypes
  * @{
  */

#ifdef DATA_IN_ExtSRAM
  static void SystemInit_ExtMemCtl(void); 
#endif /* DATA_IN_ExtSRAM */

/**
  * @}
  */

/** @addtogroup STM32F2xx_System_Private_Functions
  * @{
  */

/*+ MBED */
#if 0
/*- MBED */

/**
  * @brief  Setup the microcontroller system
  *         Initialize the Embedded Flash Interface, the PLL and update the 
  *         SystemFrequency variable.
  * @param  None
  * @retval None
  */
void SystemInit(void)
{
  /* Reset the RCC clock configuration to the default reset state ------------*/
  /* Set HSION bit */
  RCC->CR |= (uint32_t)0x00000001;

  /* Reset CFGR register */
  RCC->CFGR = 0x00000000;

  /* Reset HSEON, CSSON and PLLON bits */
  RCC->CR &= (uint32_t)0xFEF6FFFF;

  /* Reset PLLCFGR register */
  RCC->PLLCFGR = 0x24003010;

  /* Reset HSEBYP bit */
  RCC->CR &= (uint32_t)0xFFFBFFFF;

  /* Disable all interrupts */
  RCC->CIR = 0x00000000;

#ifdef DATA_IN_ExtSRAM
  SystemInit_ExtMemCtl(); 
#endif /* DATA_IN_ExtSRAM */

  /* Configure the Vector Table location add offset address ------------------*/
#ifdef VECT_TAB_SRAM
  SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
#else
  SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
#endif
}

/*+ MBED */
#endif
/*- MBED */

/**
  * @brief  Update SystemCoreClock variable according to Clock Register Values.
  *         The SystemCoreClock variable contains the core clock (HCLK), it can
  *         be used by the user application to setup the SysTick timer or configure
  *         other parameters.
  *           
  * @note   Each time the core clock (HCLK) changes, this function must be called
  *         to update SystemCoreClock variable value. Otherwise, any configuration
  *         based on this variable will be incorrect.         
  *     
  * @note   - The system frequency computed by this function is not the real 
  *           frequency in the chip. It is calculated based on the predefined 
  *           constant and the selected clock source:
  *             
  *           - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*)
  *                                              
  *           - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**)
  *                          
  *           - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**) 
  *             or HSI_VALUE(*) multiplied/divided by the PLL factors.
  *         
  *         (*) HSI_VALUE is a constant defined in stm32f2xx_hal_conf.h file (default value
  *             16 MHz) but the real value may vary depending on the variations
  *             in voltage and temperature.   
  *    
  *         (**) HSE_VALUE is a constant defined in stm32f2xx_hal_conf.h file (its value
  *              depends on the application requirements), user has to ensure that HSE_VALUE
  *              is same as the real frequency of the crystal used. Otherwise, this function
  *              may have wrong result.
  *                
  *         - The result of this function could be not correct when using fractional
  *           value for HSE crystal.
  *     
  * @param  None
  * @retval None
  */
void SystemCoreClockUpdate(void)
{
  uint32_t tmp = 0, pllvco = 0, pllp = 2, pllsource = 0, pllm = 2;
  
  /* Get SYSCLK source -------------------------------------------------------*/
  tmp = RCC->CFGR & RCC_CFGR_SWS;

  switch (tmp)
  {
    case 0x00:  /* HSI used as system clock source */
      SystemCoreClock = HSI_VALUE;
      break;
    case 0x04:  /* HSE used as system clock source */
      SystemCoreClock = HSE_VALUE;
      break;
    case 0x08:  /* PLL used as system clock source */

      /* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N
         SYSCLK = PLL_VCO / PLL_P
         */    
      pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) >> 22;
      pllm = RCC->PLLCFGR & RCC_PLLCFGR_PLLM;
      
      if (pllsource != 0)
      {
        /* HSE used as PLL clock source */
        pllvco = (HSE_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
      }
      else
      {
        /* HSI used as PLL clock source */
        pllvco = (HSI_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
      }

      pllp = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLP) >>16) + 1 ) *2;
      SystemCoreClock = pllvco/pllp;
      break;
    default:
      SystemCoreClock = HSI_VALUE;
      break;
  }
  /* Compute HCLK frequency --------------------------------------------------*/
  /* Get HCLK prescaler */
  tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];
  /* HCLK frequency */
  SystemCoreClock >>= tmp;
}

#ifdef DATA_IN_ExtSRAM
/**
  * @brief  Setup the external memory controller.
  *         Called in startup_stm32f2xx.s before jump to main.
  *         This function configures the external SRAM mounted on STM322xG_EVAL board
  *         This SRAM will be used as program data memory (including heap and stack).
  * @param  None
  * @retval None
  */
void SystemInit_ExtMemCtl(void)
{
  __IO uint32_t tmp = 0x00;

/*-- GPIOs Configuration -----------------------------------------------------*/
   /* Enable GPIOD, GPIOE, GPIOF and GPIOG interface clock */
  RCC->AHB1ENR   |= 0x00000078;
  /* Delay after an RCC peripheral clock enabling */
  tmp = READ_BIT(RCC->AHB1ENR, RCC_AHB1ENR_GPIODEN);
  (void)(tmp);

  /* Connect PDx pins to FSMC Alternate function */
  GPIOD->AFR[0]  = 0x00CCC0CC;
  GPIOD->AFR[1]  = 0xCCCCCCCC;
  /* Configure PDx pins in Alternate function mode */  
  GPIOD->MODER   = 0xAAAA0A8A;
  /* Configure PDx pins speed to 100 MHz */  
  GPIOD->OSPEEDR = 0xFFFF0FCF;
  /* Configure PDx pins Output type to push-pull */  
  GPIOD->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PDx pins */ 
  GPIOD->PUPDR   = 0x00000000;

  /* Connect PEx pins to FSMC Alternate function */
  GPIOE->AFR[0]  = 0xC00CC0CC;
  GPIOE->AFR[1]  = 0xCCCCCCCC;
  /* Configure PEx pins in Alternate function mode */ 
  GPIOE->MODER   = 0xAAAA828A;
  /* Configure PEx pins speed to 100 MHz */ 
  GPIOE->OSPEEDR = 0xFFFFC3CF;
  /* Configure PEx pins Output type to push-pull */  
  GPIOE->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PEx pins */ 
  GPIOE->PUPDR   = 0x00000000;

  /* Connect PFx pins to FSMC Alternate function */
  GPIOF->AFR[0]  = 0x00CCCCCC;
  GPIOF->AFR[1]  = 0xCCCC0000;
  /* Configure PFx pins in Alternate function mode */   
  GPIOF->MODER   = 0xAA000AAA;
  /* Configure PFx pins speed to 100 MHz */ 
  GPIOF->OSPEEDR = 0xFF000FFF;
  /* Configure PFx pins Output type to push-pull */  
  GPIOF->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PFx pins */ 
  GPIOF->PUPDR   = 0x00000000;

  /* Connect PGx pins to FSMC Alternate function */
  GPIOG->AFR[0]  = 0x00CCCCCC;
  GPIOG->AFR[1]  = 0x000000C0;
  /* Configure PGx pins in Alternate function mode */ 
  GPIOG->MODER   = 0x00085AAA;
  /* Configure PGx pins speed to 100 MHz */ 
  GPIOG->OSPEEDR = 0x000CAFFF;
  /* Configure PGx pins Output type to push-pull */  
  GPIOG->OTYPER  = 0x00000000;
  /* No pull-up, pull-down for PGx pins */ 
  GPIOG->PUPDR   = 0x00000000;
  
/*--FSMC Configuration -------------------------------------------------------*/
  /* Enable the FSMC interface clock */
  RCC->AHB3ENR         |= 0x00000001;

  /* Configure and enable Bank1_SRAM2 */
  FSMC_Bank1->BTCR[2]  = 0x00001011;
  FSMC_Bank1->BTCR[3]  = 0x00000201;
  FSMC_Bank1E->BWTR[2] = 0x0FFFFFFF;
}
#endif /* DATA_IN_ExtSRAM */


/**
  * @}
  */

/**
  * @}
  */
  
/**
  * @}
  */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/