File content as of revision 2:534793444c60:

#include "SysClockConf.h"
#include "mbed.h"

bool HSE_SystemClock_Config(int freq) {
    RCC_OscInitTypeDef RCC_OscInitStruct;

    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
    RCC_OscInitStruct.HSEState = RCC_HSE_ON;
    RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
    switch(freq) {
    case 36:
        RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
        break;
    case 48:
        RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL6;
        break;
    default:
        RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
    }

    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
        return false;
    }

    RCC_ClkInitTypeDef RCC_ClkInitStruct;

    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                                |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) {
        return false;
    }

    RCC_PeriphCLKInitTypeDef PeriphClkInit;

    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC|RCC_PERIPHCLK_USB;
    switch(freq) {
    case 36:
        PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV6;
        break;
    case 48:
        PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV4;
        break;
    default:
        PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV6;
    }
    PeriphClkInit.UsbClockSelection = RCC_USBPLLCLK_DIV1;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
        return false;
    }
    return true;
}

bool configSysClock(int freq) {
    HAL_RCC_DeInit();
    if (!HSE_SystemClock_Config(freq)) {
        return false;
    }
    SystemCoreClockUpdate();
    return true;
}