em3027rtc_write
static int em3027rtc_write(struct em3027rtc_softc *, uint8_t, void *, size_t);
error = em3027rtc_write(sc, EM3027_CONTROL_BASE, &ctl, sizeof(ctl));
return em3027rtc_write(sc, reg, &val, 1);
error = em3027rtc_write(sc, EM3027_WATCH_BASE, &w, sizeof(w));