mk_read
dt->dt_sec = mk_read(sc, 0);
dt->dt_min = mk_read(sc, 1);
dt->dt_hour = mk_read(sc, 2);
dt->dt_wday = mk_read(sc, 3);
dt->dt_day = mk_read(sc, 4);
dt->dt_mon = mk_read(sc, 5);
dt->dt_year = mk_read(sc, 6);
static int mk_read (struct mkclock_softc *, int);