IG4_CTL_SPEED_MASK
(sc->cfg.bus_speed & IG4_CTL_SPEED_MASK) == IG4_CTL_SPEED_STD ?
(sc->cfg.bus_speed & IG4_CTL_SPEED_MASK));
sc->cfg.bus_speed = reg_read(sc, IG4_REG_CTL) & IG4_CTL_SPEED_MASK;