CPSW_SL_MACCONTROL
reg = cpsw_read_4(sc->swsc, CPSW_SL_MACCONTROL(sc->unit));
cpsw_write_4(sc->swsc, CPSW_SL_MACCONTROL(sc->unit), reg);
reg = cpsw_read_4(sc->swsc, CPSW_SL_MACCONTROL(sc->unit));
cpsw_write_4(sc->swsc, CPSW_SL_MACCONTROL(sc->unit), reg);
reg = CPSW_SL_MACCONTROL(sc->unit);