tl_miibus_writereg
sc->sc_mii.mii_writereg = tl_miibus_writereg;
void tl_miibus_writereg(struct device *, int, int, int);
tl_miibus_writereg(dev, i, MII_BMCR, flags);
tl_miibus_writereg(dev, 31, MII_BMCR, BMCR_ISO);