XENON_SYS_OP_CTRL
reg = bus_read_4(sc->mem_res, XENON_SYS_OP_CTRL);
bus_write_4(sc->mem_res, XENON_SYS_OP_CTRL, reg);
reg = bus_read_4(sc->mem_res, XENON_SYS_OP_CTRL);
bus_write_4(sc->mem_res, XENON_SYS_OP_CTRL, reg);
bus_write_4(sc->mem_res, XENON_SYS_OP_CTRL, reg);
bus_write_4(sc->mem_res, XENON_SYS_OP_CTRL, reg);
reg = bus_read_4(sc->mem_res, XENON_SYS_OP_CTRL);
bus_write_4(sc->mem_res, XENON_SYS_OP_CTRL, reg);