ATI_REG_ISR
bus_space_write_4(iot, ioh, ATI_REG_ISR, 0xffffffff);
bus_space_write_4(iot, ioh, ATI_REG_ISR, 0xffffffff);
status = bus_space_read_4(iot, ioh, ATI_REG_ISR);
bus_space_write_4(iot, ioh, ATI_REG_ISR, status);