COM_REG_TXDATA
com0addr[COM_REG_TXDATA] = c;
[COM_REG_TXDATA] = AUCOM_TXDATA,
[COM_REG_TXDATA] = MIO_UART_THR_OFFSET,
[COM_REG_TXDATA] = RA_UART_TBR,
CSR_WRITE_MULTI(regsp, COM_REG_TXDATA, sc->sc_tba, n);
[COM_REG_TXDATA] = com_data,
CSR_WRITE_MULTI(regsp, COM_REG_TXDATA, sc->sc_tba, n);
CSR_WRITE_1(regsp, COM_REG_TXDATA, c);