CHVGPIO_INTERRUPT_STATUS
bus_write_4(sc->sc_mem_res, CHVGPIO_INTERRUPT_STATUS, 0xffff);
reg = bus_read_4(sc->sc_mem_res, CHVGPIO_INTERRUPT_STATUS);
bus_write_4(sc->sc_mem_res, CHVGPIO_INTERRUPT_STATUS, 1 << line);