xuartns550.c

powerpc405下linux的串口驱动程序

* polled or interrupt driven modes. This function is non-blocking such that
* it will return before the data has been sent by the UART.
*
* In a polled mode, this function will only send as much data as the UART can
* buffer, either in the transmitter or in the FIFO if present and enabled.
* The application may need to call it repeatedly to send a buffer.
*
* In interrupt mode, this function will start sending the specified buffer and
* then the interrupt handler of the driver will continue until the buffer
* has been sent. A callback function, as specified by the application, will
* be called to indicate the completion of sending the buffer.
*
* @param    InstancePtr is a pointer to the XUartNs550 instance to be worked on.
*
* @return
*
* NumBytes is the number of bytes actually sent (put into the UART tranmitter
* and/or FIFO).
*
* @note
*
* None.
*
*****************************************************************************/
unsigned int XUartNs550_SendBuffer(XUartNs550 *InstancePtr)
{
    unsigned int SentCount = 0;
    unsigned int BytesToSend = 0;   /* default to not send anything */
    unsigned int FifoSize;
    Xuint8 LsrRegister;
    Xuint8 IirRegister;
    Xuint8 IerRegister;

    /* Read the line status register to determine if the transmitter is
     * empty
     */
    LsrRegister = XIo_In8(InstancePtr->BaseAddress + XUN_LSR_OFFSET);

    /* If the transmitter is not empty then don't send any data, the empty
     * room in the FIFO is not available
     */
    if (LsrRegister & XUN_LSR_TX_BUFFER_EMPTY)
    {
        /*
         * Read the interrupt ID register to determine if FIFOs are enabled,
         */
        IirRegister = XIo_In8(InstancePtr->BaseAddress + XUN_IIR_OFFSET);

        /* When there are FIFOs, send up to the FIFO size. When there are
         * no FIFOs, only send 1 byte of data.
         */
        if (IirRegister & XUN_INT_ID_FIFOS_ENABLED)
        {
            /* Determine how many bytes can be sent depending on if the
             * transmitter is empty, a FIFO size of N is really N - 1 plus
             * the transmitter register
             */
            if (LsrRegister & XUN_LSR_TX_EMPTY)
            {
                FifoSize = XUN_FIFO_SIZE;
            }
            else
            {
                FifoSize = XUN_FIFO_SIZE - 1;
            }
            /* FIFOs are enabled, if the number of bytes to send is less than
             * the size of the FIFO, then send all bytes, otherwise fill the
             * FIFO
             */
            if (InstancePtr->SendBuffer.RemainingBytes < FifoSize)
            {
                BytesToSend = InstancePtr->SendBuffer.RemainingBytes;
            }
            else
            {
                BytesToSend = FifoSize;
            }
        }
        else if (InstancePtr->SendBuffer.RemainingBytes > 0)
        {
            /*
             * Without FIFOs, we can only send 1 byte. We needed to check
             * for non-zero remaining bytes in case this routine was called
             * only to kick the transmitter and enable the UART interrupt.
             */
            BytesToSend = 1;
        }

        /*
         * Fill the FIFO if it's present or the transmitter only from the
         * the buffer that was specified
         */
        for (SentCount = 0; SentCount < BytesToSend; SentCount++)
        {
            XIo_Out8(InstancePtr->BaseAddress + XUN_THR_OFFSET,
                     InstancePtr->SendBuffer.NextBytePtr[SentCount]);
        }
    }
    /*
     * Update the buffer to reflect the bytes that were sent from it
     */
    InstancePtr->SendBuffer.NextBytePtr += SentCount;
    InstancePtr->SendBuffer.RemainingBytes -= SentCount;

    /*
     * Increment associated counters
     */
     InstancePtr->Stats.CharactersTransmitted += SentCount;

    /* If interrupts are enabled as indicated by the receive interrupt, then
     * enable the transmit interrupt, it is not enabled continuously because it
     * causes an interrupt whenever the FIFO is empty
     */
    IerRegister = XIo_In8(InstancePtr->BaseAddress + XUN_IER_OFFSET);
    if (IerRegister & XUN_IER_RX_DATA)
    {
        XIo_Out8(InstancePtr->BaseAddress + XUN_IER_OFFSET,
                 IerRegister | XUN_IER_TX_EMPTY);
    }
    /*
     * Return the number of bytes that were sent, althought they really were
     * only put into the FIFO, not completely sent yet
     */
    return SentCount;
}

/****************************************************************************/
/**
*
* This function receives a buffer that has been previously specified by setting
* up the instance variables of the instance. This function is designed to be
* an internal function for the XUartNs550 component such that it may be called
* from a shell function that sets up the buffer or from an interrupt handler.
*
* This function will attempt to receive a specified number of bytes of data
* from the UART and store it into the specified buffer. This function is
* designed for either polled or interrupt driven modes. It is non-blocking
* such that it will return if there is no data has already received by the
* UART.
*
* In a polled mode, this function will only receive as much data as the UART
* can buffer, either in the receiver or in the FIFO if present and enabled.
* The application may need to call it repeatedly to receive a buffer. Polled
* mode is the default mode of operation for the driver.
*
* In interrupt mode, this function will start receiving and then the interrupt
* handler of the driver will continue until the buffer has been received. A
* callback function, as specified by the application, will be called to indicate
* the completion of receiving the buffer or when any receive errors or timeouts
* occur. Interrupt mode must be enabled using the SetOptions function.
*
* @param    InstancePtr is a pointer to the XUartNs550 instance to be worked on.
*
* @return
*
* The number of bytes received.
*
* @note
*
* None.
*
*****************************************************************************/
unsigned int XUartNs550_ReceiveBuffer(XUartNs550 *InstancePtr)
{
    Xuint8 LsrRegister;
    unsigned int ReceivedCount = 0;

    /* Loop until there is not more data buffered by the UART or the specified
     * number of bytes is received
     */
    while (ReceivedCount < InstancePtr->ReceiveBuffer.RemainingBytes)
    {
        /* Read the Line Status Register to determine if there is any data in
         * the receiver/FIFO
         */
        LsrRegister = XIo_In8(InstancePtr->BaseAddress +
                  XUN_LSR_OFFSET);

        /* If there is a break condition then a zero data byte was put into
         * the receiver, just read it and dump it and update the stats
         */
        if (LsrRegister & XUN_LSR_BREAK_INT)
        {
            (void)XIo_In8(InstancePtr->BaseAddress + XUN_RBR_OFFSET);
            XUartNs550_mUpdateStats(InstancePtr, LsrRegister);
        }

        /* If there is data ready to be removed, then put the next byte
         * received into the specified buffer and update the stats to reflect
         * any receive errors for the byte
         */
        else if (LsrRegister & XUN_LSR_DATA_READY)
        {
            InstancePtr->ReceiveBuffer.NextBytePtr[ReceivedCount++] =
                XIo_In8(InstancePtr->BaseAddress + XUN_RBR_OFFSET);

            XUartNs550_mUpdateStats(InstancePtr, LsrRegister);
        }

        /* There's no more data buffered, so exit such that this function does
         * not block waiting for data
         */
        else
        {
            break;
        }
    }

    /* Update the receive buffer to reflect the number of bytes that was
     * received
     */
    InstancePtr->ReceiveBuffer.NextBytePtr += ReceivedCount;
    InstancePtr->ReceiveBuffer.RemainingBytes -= ReceivedCount;

    /*
     * Increment associated counters in the statistics
     */
    InstancePtr->Stats.CharactersReceived += ReceivedCount;

    return ReceivedCount;
}

/*****************************************************************************
*
* Sets the baud rate for the specified UART. Checks the input value for
* validity and also verifies that the requested rate can be configured to
* within the 3 percent error range for RS-232 communications. If the provided
* rate is not valid, the current setting is unchanged.
*
* This function is designed to be an internal function only used within the
* XUartNs550 component. It is necessary for initialization and for the user
* available function that sets the data format.
*
* @param    InstancePtr is a pointer to the XUartNs550 instance to be worked on.
* @param    BaudRate to be set in the hardware.
*
* @return
*
* - XST_SUCCESS if everything configures as expected
* - XST_UART_BAUD_ERROR if the requested rate is not available because
*       there was too much error due to the input clock
*
* @note
*
* None.
*
*****************************************************************************/
XStatus XUartNs550_SetBaudRate(XUartNs550 *InstancePtr, Xuint32 BaudRate)
{

    Xuint8 BaudLSB;
    Xuint8 BaudMSB;
    Xuint8 LcrRegister;
    Xuint32 Divisor;
    Xuint32 TargetRate;
    Xuint32 Error;
    Xuint32 PercentError;

    /*
     * Assert validates the input arguments
     */
    XASSERT_NONVOID(InstancePtr != XNULL);
    XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

    /*
     * Determine what the divisor should be to get the specified baud
     * rater based upon the input clock frequency and a baud clock prescaler
     * of 16
     */
    Divisor = InstancePtr->InputClockHz / (BaudRate * 16UL);

    /*
     * check for too much error between the baud rate that will be generated
     * using the divisor and the expected baud rate, integer division also
     * truncates always positive
     */
    TargetRate = Divisor * BaudRate * 16UL;
    Error = InstancePtr->InputClockHz - TargetRate;

    /*
     * Error has total error now compute the percentage multiplied by 100 to
     * avoid floating point calculations, should be less than 3% as per RS-232
     * spec
     */
    PercentError = (Error * 100UL) / InstancePtr->InputClockHz;
    if (PercentError > XUN_MAX_BAUD_ERROR_RATE)
    {
        return XST_UART_BAUD_ERROR;

    }

    /* Get the least significant and most significant bytes of the divisor
     * so they can be written to 2 byte registers
     */
    BaudLSB = Divisor & XUN_DIVISOR_BYTE_MASK;
    BaudMSB = (Divisor >> 8) & XUN_DIVISOR_BYTE_MASK;

    /* Save the baud rate in the instance so that the get baud rate function
     * won't have to calculate it from the divisor
     */
    InstancePtr->BaudRate = BaudRate;

    /* Get the line control register contents and set the divisor latch
     * access bit so the baud rate can be set
     */
    LcrRegister = XIo_In8(InstancePtr->BaseAddress + XUN_LCR_OFFSET);

    XIo_Out8(InstancePtr->BaseAddress + XUN_LCR_OFFSET,
             LcrRegister | XUN_LCR_DLAB);

    /*
     * Set the baud Divisors to set rate, the initial write of 0xFF is to keep
     * the divisor from being 0 which is not recommended as per the NS16550D
     * spec sheet
     */
    XIo_Out8(InstancePtr->BaseAddress + XUN_DRLS_OFFSET, 0xFF);
    XIo_Out8(InstancePtr->BaseAddress + XUN_DRLM_OFFSET, BaudMSB);
    XIo_Out8(InstancePtr->BaseAddress + XUN_DRLS_OFFSET, BaudLSB);

    /*
     * Clear the Divisor latch access bit, DLAB to allow nornal
     * operation and write to the line control register
     */
    XIo_Out8(InstancePtr->BaseAddress + XUN_LCR_OFFSET, LcrRegister);

    return XST_SUCCESS;
}

/****************************************************************************/
/**
*
* This function is a stub handler that is the default handler such that if the
* application has not set the handler when interrupts are enabled, this
* function will be called. The function interface has to match the interface
* specified for a handler even though none of the arguments are used.
*
* @param    CallBackRef is unused by this function.
* @param    Event is unused by this function.
* @param    ByteCount is unused by this function.
*
* @return
*
* None.
*
* @note
*
* None.
*
*****************************************************************************/
static void XUartNs550_StubHandler(void *CallBackRef, Xuint32 Event,
                                   unsigned int ByteCount)
{
    /*
     * Assert occurs always since this is a stub and should never be called
     */

    XASSERT_VOID_ALWAYS();
}