UART_CONTROL_REG
control = bus_space_read_4(sc->sc_bst, sc->sc_bsh, UART_CONTROL_REG);
bus_space_write_4(sc->sc_bst, sc->sc_bsh, UART_CONTROL_REG, control);
control = bus_space_read_4(sc->sc_bst, sc->sc_bsh, UART_CONTROL_REG);
bus_space_write_4(sc->sc_bst, sc->sc_bsh, UART_CONTROL_REG, control);
control = bus_space_read_4(sc->sc_bst, sc->sc_bsh, UART_CONTROL_REG);
bus_space_write_4(sc->sc_bst, sc->sc_bsh, UART_CONTROL_REG, control);