IOAT_CHANCTRL_OFFSET
writew(IOAT_CHANCTRL_RUN, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
writew(IOAT_CHANCTRL_RUN, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
writew(chanctrl, registers + IOAT_CHANCTRL_OFFSET);