CCS/MSP432P401R: MSP432

TI provides the driverlib which takes care about most of the initialization functions required for the device setup. Below you can see the HFXT startup function from this library as reference so you can compare.

In general using the driverlib can make many things easier and save time and development effort. Additional Info can be found here:

http://dev.ti.com/tirex/#/?link=Software%2FSimpleLink%20MSP432P4%20SDK%2FDocuments%2FDriverLib

bool CS_startLFXTWithTimeout(uint32_t xtDrive, uint32_t timeout)
{
    uint8_t bNMIStatus;
    bool boolBypassMode, boolTimeout;

    ASSERT(lfxtFreq != 0)
    ASSERT(
            (xtDrive == CS_LFXT_DRIVE0) || (xtDrive == CS_LFXT_DRIVE1)
            || (xtDrive == CS_LFXT_DRIVE2)
            || (xtDrive == CS_LFXT_DRIVE3)
            || (xtDrive == CS_LFXT_BYPASS));

    /* Unlocking the CS Module */
    CS->KEY = CS_KEY;

    /* Saving status and temporarily disabling NMIs for UCS faults */
#ifdef __MCU_HAS_SYSCTL_A__
    bNMIStatus = SysCtl_A_getNMISourceStatus() & SYSCTL_A_CS_SRC;
    SysCtl_A_disableNMISource(SYSCTL_A_CS_SRC);
#else
    bNMIStatus = SysCtl_getNMISourceStatus() & SYSCTL_CS_SRC;
    SysCtl_disableNMISource(SYSCTL_CS_SRC);
#endif
    boolBypassMode = (xtDrive == CS_LFXT_BYPASS) ? true : false;
    boolTimeout = (timeout == 0) ? false : true;

    /* Setting to maximum drive strength  */
    if (boolBypassMode)
    {
        BITBAND_PERI(CS->CTL2, CS_CTL2_LFXTBYPASS_OFS) = 1;
    } else
    {
        CS->CTL2 |= (CS_LFXT_DRIVE3);
        BITBAND_PERI(CS->CTL2, CS_CTL2_LFXTBYPASS_OFS) = 0;
    }

    /* Waiting for frequency stabilization */
    BITBAND_PERI(CS->CTL2, CS_CTL2_LFXT_EN_OFS) = 1;

    while (BITBAND_PERI(CS->IFG, CS_IFG_LFXTIFG_OFS))
    {
        if (boolTimeout && ((--timeout) == 0))
            break;

        BITBAND_PERI(CS->CLRIFG,CS_CLRIFG_CLR_LFXTIFG_OFS) = 1;
    }

    /* Setting the drive strength */
    if (!boolBypassMode)
    {
        CS->CTL2 = ((CS->CTL2 & ~CS_LFXT_DRIVE3) | xtDrive);
    }

    /* Locking the module */
    BITBAND_PERI(CS->KEY, CS_KEY_KEY_OFS) = 1;

    /* Enabling the NMI state */
#ifdef __MCU_HAS_SYSCTL_A__
    SysCtl_A_enableNMISource(bNMIStatus);
#else
    SysCtl_enableNMISource(bNMIStatus);
#endif

    if (boolTimeout && timeout == 0)
        return false;

    return true;
}