xiuos3/arch/arm/cortex-m4/system_init.c

/**
  ******************************************************************************
  * @file    system_stm32f4xx.c
  * @author  MCD Application Team
  * @brief   CMSIS Cortex-M4 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_stm32f4xx.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 2017 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.
  *
  ******************************************************************************
  */

/**
* @file system_init.c
* @brief support SystemInit function
* @version 1.0 
* @author AIIT XUOS Lab
* @date 2021-04-29
*/

/*************************************************
File name: system_init.c
Description: support SystemInit function
Others: 
History: 
1. Date: 2021-04-29
Author: AIIT XUOS Lab
Modification: 
1. take system_stm32f4xx.c for XiUOS
*************************************************/

#include "stm32f4xx.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 */

#define VECT_TAB_OFFSET  0x00

void SystemInit(void)
{
    SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2));

    RCC->CR |= (uint32_t)0x00000001;
    RCC->CFGR = 0x00000000;
    RCC->CR &= (uint32_t)0xFEF6FFFF;
    RCC->PLLCFGR = 0x24003010;
    RCC->CR &= (uint32_t)0xFFFBFFFF;
    RCC->CIR = 0x00000000;

#if defined (DATA_IN_ExtSRAM) || defined (DATA_IN_ExtSDRAM)
    SystemInitExtMemCtl(); 
#endif

#ifdef VECT_TAB_SRAM
    SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET;
#else
    SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET;
#endif
}