PRESCALE
DIV_ROUND_CLOSEST(ttce->ttc.freq, PRESCALE * HZ));
err = clocksource_register_hz(&ttccs->cs, ttccs->ttc.freq / PRESCALE);
ttccs->ttc.freq / PRESCALE);
clockevents_update_freq(&ttcce->ce, ndata->new_rate / PRESCALE);
ttcce->ttc.freq / PRESCALE, 1, 0xfffe);