SERIAL_LCR_DLAB
Data = mos7840_port->shadowLCR | SERIAL_LCR_DLAB;
Data = mos7840_port->shadowLCR & ~SERIAL_LCR_DLAB;
Data |= SERIAL_LCR_DLAB; /* data latch enable in LCR 0x80 */
Data = Data & ~SERIAL_LCR_DLAB;