ETH_DP_SEL
ret = lan78xx_wait_for_bits(sc, ETH_DP_SEL, ETH_DP_SEL_DPRDY_);
ret = lan78xx_read_reg(sc, ETH_DP_SEL, &dp_sel);
ret = lan78xx_write_reg(sc, ETH_DP_SEL, dp_sel);
ret = lan78xx_wait_for_bits(sc, ETH_DP_SEL, ETH_DP_SEL_DPRDY_);