ath_calibrate
static void ath_calibrate(void *);
callout_reset(&sc->sc_cal_ch, 1, ath_calibrate, sc);
callout_reset(&sc->sc_cal_ch, nextcal, ath_calibrate, sc);
callout_reset(&sc->sc_cal_ch, 1, ath_calibrate, sc);
callout_reset(&sc->sc_cal_ch, 1, ath_calibrate, sc);