PPS_MAX_SOURCES
err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
__unregister_chrdev(pps_major, 0, PPS_MAX_SOURCES, "pps");
pps_major = __register_chrdev(0, 0, PPS_MAX_SOURCES, "pps",