FEC_ATIME_CORR
writel(corr_period, fep->hwp + FEC_ATIME_CORR);
fep->ptp_saved_state.at_corr = readl(fep->hwp + FEC_ATIME_CORR);
writel(fep->ptp_saved_state.at_corr, fep->hwp + FEC_ATIME_CORR);