nsysccr is Nintendo System CCR which interfaces with the IOS-PAD part of IOSU through various /dev nodes. See the IOSU wiki page for a list.

Reverse Engineered (Pseudo)Code

void CCREnableFwUpdateMode(void)
{
    if(bspWrite("CCRH", 0, "Reset") == 0) //bspWrite in coreinit, interfaces with IOS-BSP
        COSWarn(1, "Successfully reset host and ENabled fw update\n");
    else
        COSWarn(1, "FAILED to reset host and enable fw update\n");
    COSWarn(1, "Wait 3 seconds for HOST to deatach and attach\n"); //Typo in binary
    OSSleepTicks((int64_t)3 * (OSGetSystemInfo()->busClockSpeed / 4));
}

void CCRDisableFwUpdateMode(void)
{
    if(bspWrite("CCRH", 0, "Reset") == 0) //bspWrite in coreinit, interfaces with IOS-BSP
        COSWarn(1, "Successfully reset host and DISabled fw update\n");
    else
        COSWarn(1, "FAILED to reset host and disable fw update\n");
    COSWarn(1, "Wait 3 seconds for HOST to deatach and attach\n"); //Typo in binary
    OSSleepTicks((int64_t)3 * (OSGetSystemInfo()->busClockSpeed / 4));
}

void CCRHIDSetup(void)
{
    COSInfo(6, "%s() depricated, no need to call\n", "CCRHIDSetup"); //Typo in binary
    return 0;
}

void CCRHIDTeardown(void)
{
    COSInfo(6, "%s() depricated, no need to call\n", "CCRHIDTeardown"); //Typo in binary
    return 0;
}