HPET_FREQ
#define HPET_COMPARE_VAL ((HPET_FREQ + HZ / 2) / HZ)
clockevent_set_clock(cd, HPET_FREQ);
csrc_hpet.mult = clocksource_hz2mult(HPET_FREQ, csrc_hpet.shift);
return clocksource_register_hz(&csrc_hpet, HPET_FREQ);