uartgba.c

含有完整TCP/IP PPP协议的嵌入式操作系统

/*
 * Copyright (C) 2001-2005 by egnite Software GmbH. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL EGNITE
 * SOFTWARE GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * For additional information see http://www.ethernut.de/
 */

/*
 * $Log: uartgba.c,v $
 * Revision 1.3  2005/10/24 17:59:19  haraldkipp
 * Use correct header file, arm, not gba.
 *
 * Revision 1.2  2005/08/02 17:46:45  haraldkipp
 * Major API documentation update.
 *
 * Revision 1.1  2005/07/26 18:02:26  haraldkipp
 * Moved from dev.
 *
 * Revision 1.1  2005/04/05 18:01:43  haraldkipp
 * This code is buggy! Anyone willing to help?
 *
 */

#include <sys/atom.h>
#include <sys/event.h>
#include <sys/timer.h>

#include <dev/irqreg.h>

#include <arch/arm.h>
#include <dev/usart.h>

#include <stdio.h>
/*!
 * \addtogroup xgUartGba
 */
/*@{*/

/* \brief ASCII code for software flow control, starts transmitter. */
#define ASCII_XON   0x11
/* \brief ASCII code for software flow control, stops transmitter. */
#define ASCII_XOFF  0x13

/* \brief XON transmit pending flag. */
#define XON_PENDING     0x10
/* \brief XOFF transmit pending flag. */
#define XOFF_PENDING    0x20
/* \brief XOFF sent flag. */
#define XOFF_SENT       0x40
/* \brief XOFF received flag. */
#define XOFF_RCVD       0x80


/*!
 * \brief Receiver error flags.
 */
//static ureg_t rx_errors;

/*!
 * \brief Enables software flow control if not equal zero.
 */
static ureg_t flow_control;

static volatile ureg_t tx_stop = 1;

static USARTDCB dcb_uart;

/*
 * \brief USART0 transmit data register empty interrupt handler.
 *
 * \param arg Pointer to the transmitter ring buffer.
 */
static void GbaUartTxEmpty(RINGBUF * rbf)
{
    register u_char *cp = rbf->rbf_tail;

    /*
     * Process pending software flow controls first.
     */
    if (flow_control & (XON_PENDING | XOFF_PENDING)) {
        if (flow_control & XON_PENDING) {
            outw(REG_SIODATA8, ASCII_XOFF);
            flow_control |= XOFF_SENT;
        } else {
            outw(REG_SIODATA8, ASCII_XON);
            flow_control &= ~XOFF_SENT;
        }
        flow_control &= ~(XON_PENDING | XOFF_PENDING);
        return;
    }

    if (flow_control & XOFF_RCVD) {
        /* 
         * If XOFF has been received, we disable the transmit interrupts
         * and return without sending anything.
         */
        tx_stop = 1;
        outw(REG_SIOCNT, inw(REG_SIOCNT) & ~SIO_SEND_ENA);
        return;
    }

    if (rbf->rbf_cnt) {

        rbf->rbf_cnt--;

        /*
         * Start transmission of the next character.
         */
        outw(REG_SIODATA8, *cp);

        /*
         * Wrap around the buffer pointer if we reached its end.
         */
        if (++cp == rbf->rbf_last) {
            cp = rbf->rbf_start;
        }
        rbf->rbf_tail = cp;
        if (rbf->rbf_cnt == rbf->rbf_lwm) {
            NutEventPostFromIrq(&rbf->rbf_que);
        }
    }

    /*
     * Nothing left to transmit, disable interrupt.
     */
    else {
        tx_stop = 1;
        outw(REG_SIOCNT, (inw(REG_SIOCNT) & ~SIO_SEND_ENA) | SIO_TX_FULL);
        rbf->rbf_cnt = 0;
        NutEventPostFromIrq(&rbf->rbf_que);
    }
}

/*
 * \brief USART0 receive complete interrupt handler.
 *
 *
 * \param arg Pointer to the receiver ring buffer.
 */
static void GbaUartRxFull(RINGBUF * rbf)
{
    register size_t cnt;
    register u_char ch;

    /*
     * We read the received character as early as possible to avoid overflows
     * caused by interrupt latency. However, reading the error flags must come 
     * first, because reading the ATmega128 data register clears the status.
     */
    //TODO rx_errors |= inb(UCSRnA);
    ch = (u_char) inw(REG_SIODATA8);

    /*
     * Handle software handshake. We have to do this before checking the
     * buffer, because flow control must work in write-only mode, where
     * there is no receive buffer.
     */
    if (flow_control) {
        /* XOFF character disables transmit interrupts. */
        if (ch == ASCII_XOFF) {
            tx_stop = 1;
            outw(REG_SIOCNT, inw(REG_SIOCNT) & ~SIO_SEND_ENA);
            flow_control |= XOFF_RCVD;
            return;
        }
        /* XON enables transmit interrupts. */
        else if (ch == ASCII_XON) {
            tx_stop = 0; //TODO
            outw(REG_SIOCNT, inw(REG_SIOCNT) | SIO_SEND_ENA);
            flow_control &= ~XOFF_RCVD;
            return;
        }
    }

    /*
     * Check buffer overflow.
     */
    cnt = rbf->rbf_cnt;
    if (cnt >= rbf->rbf_siz) {
        //TODO rx_errors |= _BV(DOR);
        return;
    }

    /* Wake up waiting threads if this is the first byte in the buffer. */
    if (cnt++ == 0) {
        NutEventPostFromIrq(&rbf->rbf_que);
    }

    /*
     * Check the high watermark for software handshake. If the number of 
     * buffered bytes is above this mark, then send XOFF.
     */
    else if (flow_control) {
        if (cnt >= rbf->rbf_hwm) {
            if ((flow_control & XOFF_SENT) == 0) {
                if (inw(REG_SIOCNT) & SIO_TX_FULL) {
                    flow_control |= XOFF_PENDING;
                } else {
                    outw(REG_SIODATA8, ASCII_XOFF);
                    flow_control |= XOFF_SENT;
                    flow_control &= ~XOFF_PENDING;
                }
            }
        }
    }

    /* 
     * Store the character and increment and the ring buffer pointer. 
     */
    *rbf->rbf_head++ = ch;
    if (rbf->rbf_head == rbf->rbf_last) {
        rbf->rbf_head = rbf->rbf_start;
    }

    /* Update the ring buffer counter. */
    rbf->rbf_cnt = cnt;
}

static void GbaUartIsr(void *arg)
{
    /* Clear interrupt. */
    outw(REG_IF, INT_SIO);

    if ((inw(REG_SIOCNT) & SIO_RX_EMPTY) == 0) {
        GbaUartRxFull(&((USARTDCB *) arg)->dcb_rx_rbf);
    }
    if ((inw(REG_SIOCNT) & SIO_TX_FULL) == 0) {
        GbaUartTxEmpty(&((USARTDCB *) arg)->dcb_tx_rbf);
    }
}

/*!
 * \brief Carefully enable USART hardware functions.
 *
 * Always enabale transmitter and receiver, even on read-only or
 * write-only mode. So we can support software flow control.
 */
static void GbaUartEnable(void)
{
    NutEnterCritical();

    //TODO outb(UCSRnB, _BV(RXCIE) | _BV(UDRIE) | _BV(RXEN) | _BV(TXEN));

    NutExitCritical();
}

/*!
 * \brief Carefully disable USART hardware functions.
 */
static void GbaUartDisable(void)
{
    /*
     * Disable USART interrupts.
     */
    //TODO NutEnterCritical();
    //TODO cbi(UCSRnB, RXCIE);
    //TODO cbi(UCSRnB, TXCIE);
    //TODO cbi(UCSRnB, UDRIE);
    //TODO NutExitCritical();

    /*
     * Allow incoming or outgoing character to finish.
     */
    //TODO NutDelay(10);

    /*
     * Disable USART transmit and receive.
     */
    //TODO cbi(UCSRnB, RXEN);
    //TODO cbi(UCSRnB, TXEN);
}

/*!
 * \brief Query the USART hardware for the selected speed.
 *
 * This function is called by ioctl function of the upper level USART 
 * driver through the USARTDCB jump table.
 *
 * \return The currently selected baudrate.
 */
static u_long GbaUartGetSpeed(void)
{
    u_short sv = inw(REG_SIOCNT);

    if ((sv & SIO_BAUD_115200) == SIO_BAUD_115200) {
        return 115200UL;
    }
    if ((sv & SIO_BAUD_57600) == SIO_BAUD_57600) {
        return 57600UL;
    }
    if ((sv & SIO_BAUD_38400) == SIO_BAUD_38400) {
        return 38400L;
    }
    return 9600UL;
}

/*!
 * \brief Set the USART hardware bit rate.
 *
 * This function is called by ioctl function of the upper level USART 
 * driver through the USARTDCB jump table.
 *
 * \param rate Number of bits per second.
 *
 * \return 0 on success, -1 otherwise.
 */
static int GbaUartSetSpeed(u_long rate)
{
    u_short sv;

    GbaUartDisable();
    sv = inw(REG_SIOCNT) & ~SIO_BAUD_115200;
    if (rate == 115200) {
        sv |= SIO_BAUD_115200;
    } else {
        if (rate == 57600) {
            sv |= SIO_BAUD_57600;
        } else if (rate == 38400) {
            sv |= SIO_BAUD_38400;
        }
    }
    outw(REG_SIOCNT, sv);
    GbaUartEnable();

    return 0;
}

/*!
 * \brief Query the USART hardware for the number of data bits.
 *
 * This function is called by ioctl function of the upper level USART 
 * driver through the USARTDCB jump table.
 *
 * \return The number of data bits set.
 */
static u_char GbaUartGetDataBits(void)
{
    return 8;
}

/*!
 * \brief Set the USART hardware to the number of data bits.
 *
 * This function is called by ioctl function of the upper level USART 
 * driver through the USARTDCB jump table.
 *
 * \return 0 on success, -1 otherwise.
 */
static int GbaUartSetDataBits(u_char bits)
{
    GbaUartDisable();
    GbaUartEnable();

    /*
     * Verify the result.
     */
    if (GbaUartGetDataBits() != bits) {
        return -1;
    }
    return 0;
}

/*!
 * \brief Query the USART hardware for the parity mode.
 *
 * This routine is called by ioctl function of the upper level USART 
 * driver through the USARTDCB jump table.
 *
 * \return Parity mode, either 0 (disabled), 1 (odd) or 2 (even).
 */
static u_char GbaUartGetParity(void)
{
    return 0;
}

/*!
 * \brief Set the USART hardware to the specified parity mode.
 *
 * This routine is called by ioctl function of the upper level USART 
 * driver through the USARTDCB jump table.
 *
 * \param mode 0 (disabled), 1 (odd) or 2 (even)
 *
 * \return 0 on success, -1 otherwise.
 */
static int GbaUartSetParity(u_char mode)
{
    GbaUartDisable();