SPRD_ICLR
iclr = serial_in(port, SPRD_ICLR);
serial_out(port, SPRD_ICLR, iclr);
iclr = serial_in(port, SPRD_ICLR);
serial_out(port, SPRD_ICLR, iclr);
serial_out(port, SPRD_ICLR, sp->pdata->timeout_iclr);
serial_out(port, SPRD_ICLR, SPRD_IMSR_BREAK_DETECT);
serial_out(port, SPRD_ICLR, ~0);
serial_out(port, SPRD_ICLR, ~0);