ACKENB
busctrl |= (BUSCTL_ACK | AUTODIRECTION | ACKENB);
nsp_index_write(base, SCSIBUSCTRL, SCSI_ATN | AUTODIRECTION | ACKENB);
nsp_index_write(base, SCSIBUSCTRL, AUTODIRECTION | ACKENB);
nsp_index_write(base, SCSIBUSCTRL, bus_reg | AUTODIRECTION | ACKENB);