File content as of revision 186:707f6e361f3e:

/* mbed Microcontroller Library
* Copyright (c) 2006-2017 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

/**
  * This file configures the system clock as follows:
  *--------------------------------------------------------------------
  * System clock source   | 1- USE_PLL_HSE_EXTC (external 25 MHz clock)
  *                       | 2- USE_PLL_HSE_XTAL (external 25 MHz xtal)
  *                       | 3- USE_PLL_HSI (internal 16 MHz clock)
  *--------------------------------------------------------------------
  * SYSCLK(MHz)           |            216
  * AHBCLK (MHz)          |            216
  * APB1CLK (MHz)         |             54
  * APB2CLK (MHz)         |            108
  * USB capable (48 MHz)  |            YES
  *--------------------------------------------------------------------
**/

#include "stm32f7xx.h"
#include "mbed_assert.h"

/*!< 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. */

// clock source is selected with CLOCK_SOURCE in json config
#define USE_PLL_HSE_EXTC     0x8  // Use external clock (ST Link MCO)
#define USE_PLL_HSE_XTAL     0x4  // Use external xtal (X3 on board - not provided by default)
#define USE_PLL_HSI          0x2  // Use HSI internal clock

#if ( ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) )
uint8_t SetSysClock_PLL_HSE(uint8_t bypass);
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) */

#if ((CLOCK_SOURCE) & USE_PLL_HSI)
uint8_t SetSysClock_PLL_HSI(void);
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSI) */


/**
  * @brief  Setup the microcontroller system
  *         Initialize the Embedded Flash Interface, the PLL and update the
  *         SystemFrequency variable.
  * @param  None
  * @retval None
  */
void SystemInit(void)
{
    /* FPU settings ------------------------------------------------------------*/
#if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
    SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2));  /* set CP10 and CP11 Full Access */
#endif
    /* 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;

#if defined (DATA_IN_ExtSRAM) || defined (DATA_IN_ExtSDRAM)
    SystemInit_ExtMemCtl();
#endif /* DATA_IN_ExtSRAM || DATA_IN_ExtSDRAM */

    /* Configure the Vector Table location add offset address ------------------*/
#ifdef VECT_TAB_SRAM
    SCB->VTOR = RAMDTCM_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

}

/**
  * @brief  Configures the System clock source, PLL Multiplier and Divider factors,
  *               AHB/APBx prescalers and Flash settings
  * @note   This function should be called only once the RCC clock configuration
  *         is reset to the default reset state (done in SystemInit() function).
  * @param  None
  * @retval None
  */

void SetSysClock(void)
{
#if ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC)
    /* 1- Try to start with HSE and external clock */
    if (SetSysClock_PLL_HSE(1) == 0)
#endif
    {
#if ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL)
        /* 2- If fail try to start with HSE and external xtal */
        if (SetSysClock_PLL_HSE(0) == 0)
#endif
        {
#if ((CLOCK_SOURCE) & USE_PLL_HSI)
            /* 3- If fail start with HSI clock */
            if (SetSysClock_PLL_HSI() == 0)
#endif
            {
                while(1) {
                    MBED_ASSERT(1);
                }
            }
        }
    }

    // Output clock on MCO2 pin(PC9) for debugging purpose
    // Can be visualized on uSD card CN3 connector pin 8
    //HAL_RCC_MCOConfig(RCC_MCO2, RCC_MCO2SOURCE_SYSCLK, RCC_MCODIV_4); // 216 MHz / 4 = 54 MHz
}

#if ( ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) )
/******************************************************************************/
/*            PLL (clocked by HSE) used as System clock source                */
/******************************************************************************/
uint8_t SetSysClock_PLL_HSE(uint8_t bypass)
{
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_OscInitTypeDef RCC_OscInitStruct;
    RCC_PeriphCLKInitTypeDef RCC_PeriphClkInitStruct;

    // Enable power clock
    __PWR_CLK_ENABLE();
    __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

    // Enable HSE oscillator and activate PLL with HSE as source
    RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSE;
    if (bypass == 0) {
        RCC_OscInitStruct.HSEState          = RCC_HSE_ON; /* External xtal on OSC_IN/OSC_OUT */
    } else {
        RCC_OscInitStruct.HSEState          = RCC_HSE_BYPASS; /* External clock on OSC_IN */
    }
    // Warning: this configuration is for a 25 MHz xtal clock only
    RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSE;
    RCC_OscInitStruct.PLL.PLLM            = 25;            // VCO input clock = 1 MHz (25 MHz / 25)
    RCC_OscInitStruct.PLL.PLLN            = 432;           // VCO output clock = 432 MHz (1 MHz * 432)
    RCC_OscInitStruct.PLL.PLLP            = RCC_PLLP_DIV2; // PLLCLK = 216 MHz (432 MHz / 2)
    RCC_OscInitStruct.PLL.PLLQ            = 9;             // USB clock = 48 MHz (432 MHz / 9) --> OK for USB

    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        return 0; // FAIL
    }

    // Activate the OverDrive to reach the 216 MHz Frequency
    if (HAL_PWREx_EnableOverDrive() != HAL_OK) {
        return 0; // FAIL
    }

    // Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers
    RCC_ClkInitStruct.ClockType      = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
    RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK; // 216 MHz
    RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;         // 216 MHz
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;           //  54 MHz
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;           // 108 MHz

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7) != HAL_OK) {
        return 0; // FAIL
    }

    RCC_PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_CLK48;
    RCC_PeriphClkInitStruct.Clk48ClockSelection = RCC_CLK48SOURCE_PLL;
    if (HAL_RCCEx_PeriphCLKConfig(&RCC_PeriphClkInitStruct) != HAL_OK) {
        return 0; // FAIL
    }

    return 1; // OK
}
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSE_XTAL) || ((CLOCK_SOURCE) & USE_PLL_HSE_EXTC) */

#if ((CLOCK_SOURCE) & USE_PLL_HSI)
/******************************************************************************/
/*            PLL (clocked by HSI) used as System clock source                */
/******************************************************************************/
uint8_t SetSysClock_PLL_HSI(void)
{
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_OscInitTypeDef RCC_OscInitStruct;
    RCC_PeriphCLKInitTypeDef RCC_PeriphClkInitStruct;

    // Enable power clock
    __PWR_CLK_ENABLE();

    // Enable HSI oscillator and activate PLL with HSI as source
    RCC_OscInitStruct.OscillatorType      = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSIState            = RCC_HSI_ON;
    RCC_OscInitStruct.HSEState            = RCC_HSE_OFF;
    RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    RCC_OscInitStruct.PLL.PLLState        = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource       = RCC_PLLSOURCE_HSI;
    RCC_OscInitStruct.PLL.PLLM            = 8;            // VCO input clock = 2 MHz (16 MHz / 8)
    RCC_OscInitStruct.PLL.PLLN            = 216;           // VCO output clock = 432 MHz (2 MHz * 216)
    RCC_OscInitStruct.PLL.PLLP            = RCC_PLLP_DIV2; // PLLCLK = 216 MHz (432 MHz / 2)
    RCC_OscInitStruct.PLL.PLLQ            = 9;

    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        return 0; // FAIL
    }

    // Activate the OverDrive to reach the 216 MHz Frequency
    if (HAL_PWREx_EnableOverDrive() != HAL_OK) {
        return 0; // FAIL
    }

    // Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers
    RCC_ClkInitStruct.ClockType      = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
    RCC_ClkInitStruct.SYSCLKSource   = RCC_SYSCLKSOURCE_PLLCLK; // 216 MHz
    RCC_ClkInitStruct.AHBCLKDivider  = RCC_SYSCLK_DIV1;         // 216 MHz
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;           //  54 MHz
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;           // 108 MHz

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7) != HAL_OK) {
        return 0; // FAIL
    }

    RCC_PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_CLK48;
    RCC_PeriphClkInitStruct.Clk48ClockSelection = RCC_CLK48SOURCE_PLL;
    if (HAL_RCCEx_PeriphCLKConfig(&RCC_PeriphClkInitStruct) != HAL_OK) {
        return 0; // FAIL
    }

    return 1; // OK
}
#endif /* ((CLOCK_SOURCE) & USE_PLL_HSI) */