* ambaIoctl - special device control
*
* This routine handles the IOCTL messages from the user.
*
* RETURNS: OK on success, ENOSYS on unsupported request, EIO on failed
* request.
*/

LOCAL STATUS ambaIoctl
    (
    SIO_CHAN * pSioChan, /* ptr to SIO_CHAN describing this channel */
    int  request, /* request code */
    int  arg  /* some argument */
    )
    {
    int  oldlevel; /* current interrupt level mask */
    STATUS status;  /* status to return */
    UINT32 brd;  /* baud rate divisor */
    AMBA_CHAN * pChan = (AMBA_CHAN *)pSioChan;

    status = OK; /* preset to return OK */

    switch (request)
{
case SIO_BAUD_SET
        

     brd = (pChan->xtal/(16*arg)) - 1; /* calculate baudrate divisor */

     if ((brd < 1) || (brd > 0xFFF))
  {
  status = EIO;  /* baud rate out of range */
  break;
  }

     oldlevel = intLock ();

     /* Set baud rate divisor in UART */

     AMBA_UART_REG_WRITE(pChan, L_UBRLCR, brd & 0xFF);
     AMBA_UART_REG_WRITE(pChan, M_UBRLCR, (brd >> 8) & 0xF);

     AMBA_UART_REG_WRITE(pChan, H_UBRLCR,
  (UINT8)(WORD_LEN_8 | ONE_STOP | PARITY_NONE | FIFO_ENABLE));

     pChan->baudRate = arg;

     intUnlock (oldlevel);

     break;

case SIO_BAUD_GET:

     /* Get the baud rate and return OK */

     *(int *)arg = pChan->baudRate;
     break;

case SIO_MODE_SET

     if ((arg != SIO_MODE_POLL) && (arg != SIO_MODE_INT))
  {
  status = EIO;
  break;
  }
    
     oldlevel = intLock ();

     if (arg == SIO_MODE_INT)
  {
  /* Ensure that only Receive ints are generated. */
  AMBA_UART_REG_BIT_CLR(pChan,
          UARTCON,
                                      UART_RTIE | UART_TIE |
          UART_RIE | UART_MSIE );
  AMBA_UART_REG_BIT_SET(pChan, UARTCON, UART_RIE | UART_RTIE);

  /* Enable appropriate interrupts. */
  intEnable (pChan->lelelRX)
  }
     else
  {
  /* Disable all interrupts for this UART. */

  intDisable (pChan->levelRx);
  if (pChan->levelTx != pChan->levelRx)
      {
      intDisable (pChan->levelTx);
      }

  AMBA_UART_REG_BIT_CLR(pChan,
          UARTCON,
                                      UART_RTIE | UART_TIE |
          UART_RIE | UART_MSIE );
  }

     pChan->channelMode = arg;

     intUnlock (oldlevel);
     break;    

case SIO_MODE_GET:

     /* Get the current mode and return OK */

     *(int *)arg = pChan->channelMode;
     break;

case SIO_AVAIL_MODES_GET:

     /* Get the available modes and return OK */

     *(int *)arg = SIO_MODE_INT | SIO_MODE_POLL;
     break;

case SIO_HW_OPTS_SET:

case SIO_HW_OPTS_GET:

default:
     status = ENOSYS;
}

    return status;

    }