pc300_tty.c

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/*
 * pc300_tty.c  Cyclades-PC300(tm) TTY Driver.
 *
 * Author:  Regina Kodato <[email protected]>
 *
 * Copyright:   (c) 1999-2002 Cyclades Corp.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *   
 *  $Log: pc300_tty.c,v $
 *  Revision 3.7  2002/03/07 14:17:09  henrique
 *  License data fixed
 *
 *  Revision 3.6  2001/12/10 12:29:42  regina
 *  Fix the MLPPP bug
 *
 *  Revision 3.5  2001/10/31 11:20:05  regina
 *  automatic pppd starts
 *
 *  Revision 3.4  2001/08/06 12:01:51  regina
 *  problem in DSR_DE bit
 *
 *  Revision 3.3  2001/07/26 22:58:41  regina
 *  update EDA value
 *
 *  Revision 3.2  2001/07/12 13:11:20  regina
 *  bug fix - DCD-OFF in pc300 tty driver
 *
 *  DMA transmission bug fix
 *  
 *  Revision 3.1  2001/06/22 13:13:02  regina
 *  MLPPP implementation
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/if.h>
#include <linux/skbuff.h>
/* TTY includes */
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>

#include <asm/io.h>
#include <asm/uaccess.h>

#include "pc300.h"

/* defines and macros */
/* TTY Global definitions */
#define CPC_TTY_NPORTS  8   /* maximum number of the sync tty connections */
#define CPC_TTY_MAJOR   CYCLADES_MAJOR  
#define CPC_TTY_MINOR_START 240 /* minor of the first PC300 interface */

#define CPC_TTY_MAX_MTU 2000    

/* tty interface state */
#define CPC_TTY_ST_IDLE 0
#define CPC_TTY_ST_INIT 1   /* configured with MLPPP and up */
#define CPC_TTY_ST_OPEN 2   /* opened by application */

#define CPC_TTY_LOCK(card,flags)\
    do {\
        spin_lock_irqsave(&card->card_lock, flags); \
    } while (0)

#define CPC_TTY_UNLOCK(card,flags)  \
    do {\
        spin_unlock_irqrestore(&card->card_lock, flags);    \
    } while (0)

//#define   CPC_TTY_DBG(format,a...)    printk(format,##a)
#define CPC_TTY_DBG(format,a...)

/* data structures */
typedef struct _st_cpc_rx_buf {
    struct _st_cpc_rx_buf   *next;
    int     size;
    unsigned char   data[1];
} st_cpc_rx_buf;

struct st_cpc_rx_list {
    st_cpc_rx_buf   *first;
    st_cpc_rx_buf   *last;
};

typedef struct _st_cpc_tty_area {
    int     state;      /* state of the TTY interface */
    int     num_open;   
    unsigned int    tty_minor;  /* minor this interface */
    volatile struct st_cpc_rx_list buf_rx;  /* ptr. to reception buffer */
    unsigned char*  buf_tx;     /* ptr. to transmission buffer */
    pc300dev_t* pc300dev;   /* ptr. to info struct in PC300 driver */
    unsigned char   name[20];   /* interf. name + "-tty" */
    struct tty_struct *tty;     
    struct work_struct tty_tx_work; /* tx work - tx interrupt */
    struct work_struct tty_rx_work; /* rx work - rx interrupt */
    } st_cpc_tty_area;

/* TTY data structures */
static struct tty_driver serial_drv;

/* local variables */
static st_cpc_tty_area  cpc_tty_area[CPC_TTY_NPORTS];

static int cpc_tty_cnt = 0; /* number of intrfaces configured with MLPPP */
static int cpc_tty_unreg_flag = 0;

/* TTY functions prototype */
static int cpc_tty_open(struct tty_struct *tty, struct file *flip);
static void cpc_tty_close(struct tty_struct *tty, struct file *flip);
static int cpc_tty_write(struct tty_struct *tty, const unsigned char *buf, int count);
static int cpc_tty_write_room(struct tty_struct *tty);
static int cpc_tty_chars_in_buffer(struct tty_struct *tty);
static void cpc_tty_flush_buffer(struct tty_struct *tty);
static void cpc_tty_hangup(struct tty_struct *tty);
static void cpc_tty_rx_work(struct work_struct *work);
static void cpc_tty_tx_work(struct work_struct *work);
static int cpc_tty_send_to_card(pc300dev_t *dev,void *buf, int len);
static void cpc_tty_trace(pc300dev_t *dev, char* buf, int len, char rxtx);
static void cpc_tty_signal_off(pc300dev_t *pc300dev, unsigned char);
static void cpc_tty_signal_on(pc300dev_t *pc300dev, unsigned char);

static int pc300_tiocmset(struct tty_struct *, unsigned int, unsigned int);
static int pc300_tiocmget(struct tty_struct *);

/* functions called by PC300 driver */
void cpc_tty_init(pc300dev_t *dev);
void cpc_tty_unregister_service(pc300dev_t *pc300dev);
void cpc_tty_receive(pc300dev_t *pc300dev);
void cpc_tty_trigger_poll(pc300dev_t *pc300dev);

/*
 * PC300 TTY clear "signal"
 */
static void cpc_tty_signal_off(pc300dev_t *pc300dev, unsigned char signal)
{
    pc300ch_t *pc300chan = (pc300ch_t *)pc300dev->chan; 
    pc300_t *card = (pc300_t *) pc300chan->card; 
    int ch = pc300chan->channel; 
    unsigned long flags; 

    CPC_TTY_DBG("%s-tty: Clear signal %x\n",
        pc300dev->dev->name, signal);
    CPC_TTY_LOCK(card, flags); 
    cpc_writeb(card->hw.scabase + M_REG(CTL,ch), 
        cpc_readb(card->hw.scabase+M_REG(CTL,ch))& signal);
    CPC_TTY_UNLOCK(card,flags); 
}

/*
 * PC300 TTY set "signal" to ON
 */
static void cpc_tty_signal_on(pc300dev_t *pc300dev, unsigned char signal)
{
    pc300ch_t *pc300chan = (pc300ch_t *)pc300dev->chan; 
    pc300_t *card = (pc300_t *) pc300chan->card; 
    int ch = pc300chan->channel; 
    unsigned long flags; 

    CPC_TTY_DBG("%s-tty: Set signal %x\n",
        pc300dev->dev->name, signal);
    CPC_TTY_LOCK(card, flags); 
    cpc_writeb(card->hw.scabase + M_REG(CTL,ch), 
        cpc_readb(card->hw.scabase+M_REG(CTL,ch))& ~signal);
    CPC_TTY_UNLOCK(card,flags); 
}


static const struct tty_operations pc300_ops = {
    .open = cpc_tty_open,
    .close = cpc_tty_close,
    .write = cpc_tty_write,
    .write_room = cpc_tty_write_room,
    .chars_in_buffer = cpc_tty_chars_in_buffer,
    .tiocmset = pc300_tiocmset,
    .tiocmget = pc300_tiocmget,
    .flush_buffer = cpc_tty_flush_buffer,
    .hangup = cpc_tty_hangup,
};


/*
 * PC300 TTY initialization routine
 *
 * This routine is called by the PC300 driver during board configuration 
 * (ioctl=SIOCSP300CONF). At this point the adapter is completely
 * initialized.
 * o verify kernel version (only 2.4.x)
 * o register TTY driver
 * o init cpc_tty_area struct
 */
void cpc_tty_init(pc300dev_t *pc300dev)
{
    unsigned long port;
    int aux;
    st_cpc_tty_area * cpc_tty;

    /* hdlcX - X=interface number */
    port = pc300dev->dev->name[4] - '0';
    if (port >= CPC_TTY_NPORTS) {
        printk("%s-tty: invalid interface selected (0-%i): %li",
            pc300dev->dev->name,
            CPC_TTY_NPORTS-1,port);
        return;
    }

    if (cpc_tty_cnt == 0) { /* first TTY connection -> register driver */
        CPC_TTY_DBG("%s-tty: driver init, major:%i, minor range:%i=%i\n",
            pc300dev->dev->name,
            CPC_TTY_MAJOR, CPC_TTY_MINOR_START,
            CPC_TTY_MINOR_START+CPC_TTY_NPORTS);
        /* initialize tty driver struct */
        memset(&serial_drv,0,sizeof(struct tty_driver));
        serial_drv.magic = TTY_DRIVER_MAGIC;
        serial_drv.owner = THIS_MODULE;
        serial_drv.driver_name = "pc300_tty";
        serial_drv.name = "ttyCP";
        serial_drv.major = CPC_TTY_MAJOR;
        serial_drv.minor_start = CPC_TTY_MINOR_START;
        serial_drv.num = CPC_TTY_NPORTS;
        serial_drv.type = TTY_DRIVER_TYPE_SERIAL;
        serial_drv.subtype = SERIAL_TYPE_NORMAL;

        serial_drv.init_termios = tty_std_termios;
        serial_drv.init_termios.c_cflag = B9600|CS8|CREAD|HUPCL|CLOCAL;
        serial_drv.flags = TTY_DRIVER_REAL_RAW;

        /* interface routines from the upper tty layer to the tty driver */
        tty_set_operations(&serial_drv, &pc300_ops);

        /* register the TTY driver */
        if (tty_register_driver(&serial_drv)) { 
            printk("%s-tty: Failed to register serial driver! ",
                pc300dev->dev->name);
            return;
        } 

        memset((void *)cpc_tty_area, 0,
                                sizeof(st_cpc_tty_area) * CPC_TTY_NPORTS);
    }

    cpc_tty = &cpc_tty_area[port];
    
    if (cpc_tty->state != CPC_TTY_ST_IDLE) {
        CPC_TTY_DBG("%s-tty: TTY port %i, already in use.\n",
                pc300dev->dev->name, port);
        return;
    }

    cpc_tty_cnt++;
    cpc_tty->state = CPC_TTY_ST_INIT; 
    cpc_tty->num_open= 0;
    cpc_tty->tty_minor = port + CPC_TTY_MINOR_START;
    cpc_tty->pc300dev = pc300dev; 

    INIT_WORK(&cpc_tty->tty_tx_work, cpc_tty_tx_work);
    INIT_WORK(&cpc_tty->tty_rx_work, cpc_tty_rx_work);
    
    cpc_tty->buf_rx.first = cpc_tty->buf_rx.last = NULL;

    pc300dev->cpc_tty = (void *)cpc_tty; 
    
    aux = strlen(pc300dev->dev->name);
    memcpy(cpc_tty->name, pc300dev->dev->name, aux);
    memcpy(&cpc_tty->name[aux], "-tty", 5);
    
    cpc_open(pc300dev->dev);
    cpc_tty_signal_off(pc300dev, CTL_DTR);

    CPC_TTY_DBG("%s: Initializing TTY Sync Driver, tty major#%d minor#%i\n",
            cpc_tty->name,CPC_TTY_MAJOR,cpc_tty->tty_minor); 
    return; 
} 

/*
 * PC300 TTY OPEN routine
 *
 * This routine is called by the tty driver to open the interface 
 * o verify minor
 * o allocate buffer to Rx and Tx
 */
static int cpc_tty_open(struct tty_struct *tty, struct file *flip)
{
    int port ;
    st_cpc_tty_area *cpc_tty;

    if (!tty) { 
        return -ENODEV;
    } 

    port = tty->index;

    if ((port < 0) || (port >= CPC_TTY_NPORTS)){ 
        CPC_TTY_DBG("pc300_tty: open invalid port %d\n", port);
        return -ENODEV;
    } 

    cpc_tty = &cpc_tty_area[port];
    
    if (cpc_tty->state == CPC_TTY_ST_IDLE){
        CPC_TTY_DBG("%s: open - invalid interface, port=%d\n",
                    cpc_tty->name, tty->index);
        return -ENODEV;
    }

    if (cpc_tty->num_open == 0) { /* first open of this tty */
        if (!cpc_tty_area[port].buf_tx){
            cpc_tty_area[port].buf_tx = kmalloc(CPC_TTY_MAX_MTU,GFP_KERNEL);
            if (!cpc_tty_area[port].buf_tx) {
                CPC_TTY_DBG("%s: error in memory allocation\n",cpc_tty->name);
                return -ENOMEM;
            }
        } 

        if (cpc_tty_area[port].buf_rx.first) {
            unsigned char * aux;
            while (cpc_tty_area[port].buf_rx.first) {
                aux = (unsigned char *)cpc_tty_area[port].buf_rx.first;
                cpc_tty_area[port].buf_rx.first = cpc_tty_area[port].buf_rx.first->next;
                kfree(aux);
            }
            cpc_tty_area[port].buf_rx.first = NULL;
            cpc_tty_area[port].buf_rx.last = NULL;
        }

        cpc_tty_area[port].state = CPC_TTY_ST_OPEN;
        cpc_tty_area[port].tty = tty;
        tty->driver_data = &cpc_tty_area[port];

        cpc_tty_signal_on(cpc_tty->pc300dev, CTL_DTR);
    } 

    cpc_tty->num_open++;

    CPC_TTY_DBG("%s: opening TTY driver\n", cpc_tty->name);
    
    /* avisar driver PC300 */ 
    return 0; 
}

/*
 * PC300 TTY CLOSE routine
 *
 * This routine is called by the tty driver to close the interface 
 * o call close channel in PC300 driver (cpc_closech)
 * o free Rx and Tx buffers
 */

static void cpc_tty_close(struct tty_struct *tty, struct file *flip)
{
    st_cpc_tty_area    *cpc_tty;
    unsigned long flags;
    int res;

    if (!tty || !tty->driver_data ) {
        CPC_TTY_DBG("hdlx-tty: no TTY in close\n");
        return;
    }

    cpc_tty = (st_cpc_tty_area *) tty->driver_data;

    if ((cpc_tty->tty != tty)|| (cpc_tty->state != CPC_TTY_ST_OPEN)) {
        CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name);
        return;
    }
    
    if (!cpc_tty->num_open) {
        CPC_TTY_DBG("%s: TTY is closed\n",cpc_tty->name);
        return;
    }

    if (--cpc_tty->num_open > 0) {
        CPC_TTY_DBG("%s: TTY closed\n",cpc_tty->name);
        return;
    }

    cpc_tty_signal_off(cpc_tty->pc300dev, CTL_DTR);

    CPC_TTY_LOCK(cpc_tty->pc300dev->chan->card, flags);  /* lock irq */ 
    cpc_tty->tty = NULL;
    cpc_tty->state = CPC_TTY_ST_INIT;
    CPC_TTY_UNLOCK(cpc_tty->pc300dev->chan->card, flags); /* unlock irq */ 
    
    if (cpc_tty->buf_rx.first) {
        unsigned char * aux;
        while (cpc_tty->buf_rx.first) {
            aux = (unsigned char *)cpc_tty->buf_rx.first;
            cpc_tty->buf_rx.first = cpc_tty->buf_rx.first->next;
            kfree(aux);
        }
        cpc_tty->buf_rx.first = NULL;
        cpc_tty->buf_rx.last = NULL;
    }
    
    kfree(cpc_tty->buf_tx);
    cpc_tty->buf_tx = NULL;

    CPC_TTY_DBG("%s: TTY closed\n",cpc_tty->name);
    
    if (!serial_drv.refcount && cpc_tty_unreg_flag) {
        cpc_tty_unreg_flag = 0;
        CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name);
        if ((res=tty_unregister_driver(&serial_drv))) { 
            CPC_TTY_DBG("%s: ERROR ->unregister the tty driver error=%d\n",
                            cpc_tty->name,res);
        }
    }
    return; 
} 

/*
 * PC300 TTY WRITE routine
 *
 * This routine is called by the tty driver to write a series of characters
 * to the tty device. The characters may come from user or kernel space.
 * o verify the DCD signal
 * o send characters to board and start the transmission
 */
static int cpc_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
    st_cpc_tty_area    *cpc_tty; 
    pc300ch_t *pc300chan; 
    pc300_t *card; 
    int ch; 
    unsigned long flags; 
    struct net_device_stats *stats; 

    if (!tty || !tty->driver_data ) { 
        CPC_TTY_DBG("hdlcX-tty: no TTY in write\n");
        return -ENODEV;
    } 

    cpc_tty = (st_cpc_tty_area *) tty->driver_data; 

    if ((cpc_tty->tty != tty) ||  (cpc_tty->state != CPC_TTY_ST_OPEN)) { 
        CPC_TTY_DBG("%s: TTY is not opened\n", cpc_tty->name);
        return -ENODEV; 
    }

    if (count > CPC_TTY_MAX_MTU) { 
        CPC_TTY_DBG("%s: count is invalid\n",cpc_tty->name);
        return -EINVAL;        /* frame too big */ 
    }

    CPC_TTY_DBG("%s: cpc_tty_write data len=%i\n",cpc_tty->name,count);
    
    pc300chan = (pc300ch_t *)((pc300dev_t*)cpc_tty->pc300dev)->chan; 
    stats = &cpc_tty->pc300dev->dev->stats;
    card = (pc300_t *) pc300chan->card;
    ch = pc300chan->channel; 

    /* verify DCD signal*/ 
    if (cpc_readb(card->hw.scabase + M_REG(ST3,ch)) & ST3_DCD) { 
        /* DCD is OFF */ 
        CPC_TTY_DBG("%s : DCD is OFF\n", cpc_tty->name);
        stats->tx_errors++;
        stats->tx_carrier_errors++;
        CPC_TTY_LOCK(card, flags); 
        cpc_writeb(card->hw.scabase + M_REG(CMD, ch), CMD_TX_BUF_CLR); 
        
        if (card->hw.type == PC300_TE) { 
            cpc_writeb(card->hw.falcbase + card->hw.cpld_reg2, 
                cpc_readb(card->hw.falcbase + card->hw.cpld_reg2) & 
                ~(CPLD_REG2_FALC_LED1 << (2 *ch))); 
        }

        CPC_TTY_UNLOCK(card, flags); 

        return -EINVAL; 
    }

    if (cpc_tty_send_to_card(cpc_tty->pc300dev, (void*)buf, count)) { 
       /* failed to send */
       CPC_TTY_DBG("%s: trasmition error\n", cpc_tty->name);
       return 0;
    }
    return count; 
} 

/*
 * PC300 TTY Write Room routine
 * 
 * This routine returns the numbers of characteres the tty driver will accept
 * for queuing to be written. 
 * o return MTU
 */
static int cpc_tty_write_room(struct tty_struct *tty)
{
    st_cpc_tty_area    *cpc_tty; 

    if (!tty || !tty->driver_data ) { 
        CPC_TTY_DBG("hdlcX-tty: no TTY to write room\n");
        return -ENODEV;
    }

    cpc_tty = (st_cpc_tty_area *) tty->driver_data; 

    if ((cpc_tty->tty != tty) ||  (cpc_tty->state != CPC_TTY_ST_OPEN)) { 
        CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name);
        return -ENODEV; 
    }
    
    CPC_TTY_DBG("%s: write room\n",cpc_tty->name);
    
    return CPC_TTY_MAX_MTU;
} 

/*
 * PC300 TTY chars in buffer routine
 * 
 * This routine returns the chars number in the transmission buffer 
 * o returns 0
 */
static int cpc_tty_chars_in_buffer(struct tty_struct *tty)
{
    st_cpc_tty_area    *cpc_tty; 

    if (!tty || !tty->driver_data ) {
        CPC_TTY_DBG("hdlcX-tty: no TTY to chars in buffer\n");
        return -ENODEV; 
    }

    cpc_tty = (st_cpc_tty_area *) tty->driver_data; 

    if ((cpc_tty->tty != tty) || (cpc_tty->state != CPC_TTY_ST_OPEN)) { 
        CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name);
        return -ENODEV; 
    }
   
    return 0;
} 

static int pc300_tiocmset(struct tty_struct *tty,
              unsigned int set, unsigned int clear)
{
    st_cpc_tty_area    *cpc_tty; 

    CPC_TTY_DBG("%s: set:%x clear:%x\n", __func__, set, clear);

    if (!tty || !tty->driver_data ) {
        CPC_TTY_DBG("hdlcX-tty: no TTY to chars in buffer\n");  
        return -ENODEV; 
    }

    cpc_tty = (st_cpc_tty_area *) tty->driver_data; 

    if (set & TIOCM_RTS)
        cpc_tty_signal_on(cpc_tty->pc300dev, CTL_RTS);
    if (set & TIOCM_DTR)
        cpc_tty_signal_on(cpc_tty->pc300dev, CTL_DTR);

    if (clear & TIOCM_RTS)
        cpc_tty_signal_off(cpc_tty->pc300dev, CTL_RTS);
    if (clear & TIOCM_DTR)
        cpc_tty_signal_off(cpc_tty->pc300dev, CTL_DTR);

    return 0;
}

static int pc300_tiocmget(struct tty_struct *tty)
{
    unsigned int result;
    unsigned char status;
    unsigned long flags;
    st_cpc_tty_area  *cpc_tty = (st_cpc_tty_area *) tty->driver_data;
    pc300dev_t *pc300dev = cpc_tty->pc300dev;
    pc300ch_t *pc300chan = (pc300ch_t *)pc300dev->chan;
    pc300_t *card = (pc300_t *) pc300chan->card;
    int ch = pc300chan->channel;

    cpc_tty = (st_cpc_tty_area *) tty->driver_data;

    CPC_TTY_DBG("%s-tty: tiocmget\n",
        ((struct net_device*)(pc300dev->hdlc))->name);

    CPC_TTY_LOCK(card, flags);
    status = cpc_readb(card->hw.scabase+M_REG(CTL,ch));
    CPC_TTY_UNLOCK(card,flags);

    result = ((status & CTL_DTR) ? TIOCM_DTR : 0) |
         ((status & CTL_RTS) ? TIOCM_RTS : 0);

    return result;
}

/*
 * PC300 TTY Flush Buffer routine
 *
 * This routine resets the transmission buffer 
 */
static void cpc_tty_flush_buffer(struct tty_struct *tty)
{ 
    st_cpc_tty_area    *cpc_tty; 
    
    if (!tty || !tty->driver_data ) {
        CPC_TTY_DBG("hdlcX-tty: no TTY to flush buffer\n"); 
        return; 
    }

    cpc_tty = (st_cpc_tty_area *) tty->driver_data; 

    if ((cpc_tty->tty != tty) ||  (cpc_tty->state != CPC_TTY_ST_OPEN)) { 
        CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name);
        return; 
    }

    CPC_TTY_DBG("%s: call wake_up_interruptible\n",cpc_tty->name);

    tty_wakeup(tty);    
    return; 
} 

/*
 * PC300 TTY Hangup routine
 *
 * This routine is called by the tty driver to hangup the interface 
 * o clear DTR signal
 */

static void cpc_tty_hangup(struct tty_struct *tty)
{ 
    st_cpc_tty_area    *cpc_tty; 
    int res;

    if (!tty || !tty->driver_data ) {
        CPC_TTY_DBG("hdlcX-tty: no TTY to hangup\n");   
        return ; 
    }

    cpc_tty = (st_cpc_tty_area *) tty->driver_data; 

    if ((cpc_tty->tty != tty) || (cpc_tty->state != CPC_TTY_ST_OPEN)) {
        CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name);
        return ;
    }
    if (!serial_drv.refcount && cpc_tty_unreg_flag) {
        cpc_tty_unreg_flag = 0;
        CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name);
        if ((res=tty_unregister_driver(&serial_drv))) { 
            CPC_TTY_DBG("%s: ERROR ->unregister the tty driver error=%d\n",
                            cpc_tty->name,res);
        }
    }
    cpc_tty_signal_off(cpc_tty->pc300dev, CTL_DTR);
}

/*
 * PC300 TTY RX work routine
 * This routine treats RX work
 * o verify read buffer
 * o call the line disc. read
 * o free memory
 */
static void cpc_tty_rx_work(struct work_struct *work)
{
    st_cpc_tty_area *cpc_tty;
    unsigned long port;
    int i, j;
    volatile st_cpc_rx_buf *buf;
    char flags=0,flg_rx=1; 
    struct tty_ldisc *ld;

    if (cpc_tty_cnt == 0) return;
    
    for (i=0; (i < 4) && flg_rx ; i++) {
        flg_rx = 0;

        cpc_tty = container_of(work, st_cpc_tty_area, tty_rx_work);
        port = cpc_tty - cpc_tty_area;

        for (j=0; j < CPC_TTY_NPORTS; j++) {
            cpc_tty = &cpc_tty_area[port];
        
            if ((buf=cpc_tty->buf_rx.first) != NULL) {
                if (cpc_tty->tty) {
                    ld = tty_ldisc_ref(cpc_tty->tty);
                    if (ld) {
                        if (ld->ops->receive_buf) {
                            CPC_TTY_DBG("%s: call line disc. receive_buf\n",cpc_tty->name);
                            ld->ops->receive_buf(cpc_tty->tty, (char *)(buf->data), &flags, buf->size);
                        }
                        tty_ldisc_deref(ld);
                    }
                }   
                cpc_tty->buf_rx.first = cpc_tty->buf_rx.first->next;
                kfree((void *)buf);
                buf = cpc_tty->buf_rx.first;
                flg_rx = 1;
            }
            if (++port == CPC_TTY_NPORTS) port = 0;
        }
    }
} 

/*
 * PC300 TTY RX work routine
 *
 * This routine treats RX interrupt. 
 * o read all frames in card
 * o verify the frame size
 * o read the frame in rx buffer
 */
static void cpc_tty_rx_disc_frame(pc300ch_t *pc300chan)
{
    volatile pcsca_bd_t __iomem * ptdescr; 
    volatile unsigned char status; 
    pc300_t *card = (pc300_t *)pc300chan->card; 
    int ch = pc300chan->channel; 

    /* dma buf read */ 
    ptdescr = (pcsca_bd_t __iomem *)(card->hw.rambase + 
                RX_BD_ADDR(ch, pc300chan->rx_first_bd)); 
    while (pc300chan->rx_first_bd != pc300chan->rx_last_bd) { 
        status = cpc_readb(&ptdescr->status); 
        cpc_writeb(&ptdescr->status, 0); 
        cpc_writeb(&ptdescr->len, 0); 
        pc300chan->rx_first_bd = (pc300chan->rx_first_bd + 1) & 
                    (N_DMA_RX_BUF - 1); 
        if (status & DST_EOM) { 
            break; /* end of message */
        }
        ptdescr = (pcsca_bd_t __iomem *)(card->hw.rambase + cpc_readl(&ptdescr->next)); 
    }
}

void cpc_tty_receive(pc300dev_t *pc300dev)
{
    st_cpc_tty_area *cpc_tty; 
    pc300ch_t *pc300chan = (pc300ch_t *)pc300dev->chan; 
    pc300_t *card = (pc300_t *)pc300chan->card; 
    int ch = pc300chan->channel; 
    volatile pcsca_bd_t  __iomem * ptdescr; 
    struct net_device_stats *stats = &pc300dev->dev->stats;
    int rx_len, rx_aux; 
    volatile unsigned char status; 
    unsigned short first_bd = pc300chan->rx_first_bd;
    st_cpc_rx_buf *new = NULL;
    unsigned char dsr_rx;

    if (pc300dev->cpc_tty == NULL) { 
        return; 
    }

    dsr_rx = cpc_readb(card->hw.scabase + DSR_RX(ch));

    cpc_tty = pc300dev->cpc_tty;

    while (1) { 
        rx_len = 0;
        ptdescr = (pcsca_bd_t  __iomem *)(card->hw.rambase + RX_BD_ADDR(ch, first_bd));
        while ((status = cpc_readb(&ptdescr->status)) & DST_OSB) {
            rx_len += cpc_readw(&ptdescr->len);
            first_bd = (first_bd + 1) & (N_DMA_RX_BUF - 1);
            if (status & DST_EOM) {
                break;
            }
            ptdescr = (pcsca_bd_t __iomem *)(card->hw.rambase+cpc_readl(&ptdescr->next));
        }
            
        if (!rx_len) { 
            if (dsr_rx & DSR_BOF) {
                /* update EDA */ 
                cpc_writel(card->hw.scabase + DRX_REG(EDAL, ch), 
                        RX_BD_ADDR(ch, pc300chan->rx_last_bd)); 
            }
            kfree(new);
            return; 
        }
        
        if (rx_len > CPC_TTY_MAX_MTU) { 
            /* Free RX descriptors */ 
            CPC_TTY_DBG("%s: frame size is invalid.\n",cpc_tty->name);
            stats->rx_errors++; 
            stats->rx_frame_errors++; 
            cpc_tty_rx_disc_frame(pc300chan);
            continue;
        } 
        
        new = kmalloc(rx_len + sizeof(st_cpc_rx_buf), GFP_ATOMIC);
        if (!new) {
            cpc_tty_rx_disc_frame(pc300chan);
            continue;
        }
        
        /* dma buf read */ 
        ptdescr = (pcsca_bd_t __iomem *)(card->hw.rambase + 
                RX_BD_ADDR(ch, pc300chan->rx_first_bd)); 

        rx_len = 0; /* counter frame size */
        
        while ((status = cpc_readb(&ptdescr->status)) & DST_OSB) {
            rx_aux = cpc_readw(&ptdescr->len);
            if ((status & (DST_OVR | DST_CRC | DST_RBIT |  DST_SHRT | DST_ABT))
                || (rx_aux > BD_DEF_LEN)) {
                CPC_TTY_DBG("%s: reception error\n", cpc_tty->name);
                stats->rx_errors++; 
                if (status & DST_OVR) { 
                    stats->rx_fifo_errors++; 
                }
                if (status & DST_CRC) { 
                    stats->rx_crc_errors++; 
                }
                if ((status & (DST_RBIT | DST_SHRT | DST_ABT)) ||
                    (rx_aux > BD_DEF_LEN))  { 
                    stats->rx_frame_errors++; 
                } 
                /* discard remainig descriptors used by the bad frame */ 
                CPC_TTY_DBG("%s: reception error - discard descriptors",
                        cpc_tty->name);
                cpc_tty_rx_disc_frame(pc300chan);
                rx_len = 0;
                kfree(new);
                new = NULL;
                break; /* read next frame - while(1) */
            }

            if (cpc_tty->state != CPC_TTY_ST_OPEN) {
                /* Free RX descriptors */ 
                cpc_tty_rx_disc_frame(pc300chan);
                stats->rx_dropped++; 
                rx_len = 0; 
                kfree(new);
                new = NULL;
                break; /* read next frame - while(1) */
            }

            /* read the segment of the frame */
            if (rx_aux != 0) {
                memcpy_fromio((new->data + rx_len), 
                    (void __iomem *)(card->hw.rambase + 
                     cpc_readl(&ptdescr->ptbuf)), rx_aux);
                rx_len += rx_aux; 
            }
            cpc_writeb(&ptdescr->status,0); 
            cpc_writeb(&ptdescr->len, 0); 
            pc300chan->rx_first_bd = (pc300chan->rx_first_bd + 1) & 
                    (N_DMA_RX_BUF -1); 
            if (status & DST_EOM)break;
            
            ptdescr = (pcsca_bd_t __iomem *) (card->hw.rambase + 
                    cpc_readl(&ptdescr->next)); 
        }
        /* update pointer */ 
        pc300chan->rx_last_bd = (pc300chan->rx_first_bd - 1) & 
                    (N_DMA_RX_BUF - 1) ; 
        if (!(dsr_rx & DSR_BOF)) {
            /* update EDA */ 
            cpc_writel(card->hw.scabase + DRX_REG(EDAL, ch), 
                    RX_BD_ADDR(ch, pc300chan->rx_last_bd)); 
        }
        if (rx_len != 0) { 
            stats->rx_bytes += rx_len; 
        
            if (pc300dev->trace_on) { 
                cpc_tty_trace(pc300dev, new->data,rx_len, 'R'); 
            } 
            new->size = rx_len;
            new->next = NULL;
            if (cpc_tty->buf_rx.first == NULL) {
                cpc_tty->buf_rx.first = new;
                cpc_tty->buf_rx.last = new;
            } else {
                cpc_tty->buf_rx.last->next = new;
                cpc_tty->buf_rx.last = new;
            }
            schedule_work(&(cpc_tty->tty_rx_work));
            stats->rx_packets++;
        }
    } 
} 

/*
 * PC300 TTY TX work routine
 * 
 * This routine treats TX interrupt. 
 * o if need call line discipline wakeup
 * o call wake_up_interruptible
 */
static void cpc_tty_tx_work(struct work_struct *work)
{
    st_cpc_tty_area *cpc_tty =
        container_of(work, st_cpc_tty_area, tty_tx_work);
    struct tty_struct *tty; 

    CPC_TTY_DBG("%s: cpc_tty_tx_work init\n",cpc_tty->name);
    
    if ((tty = cpc_tty->tty) == NULL) { 
        CPC_TTY_DBG("%s: the interface is not opened\n",cpc_tty->name);
        return; 
    }
    tty_wakeup(tty);
}

/*
 * PC300 TTY send to card routine
 * 
 * This routine send data to card. 
 * o clear descriptors
 * o write data to DMA buffers
 * o start the transmission
 */
static int cpc_tty_send_to_card(pc300dev_t *dev,void* buf, int len)
{
    pc300ch_t *chan = (pc300ch_t *)dev->chan; 
    pc300_t *card = (pc300_t *)chan->card; 
    int ch = chan->channel; 
    struct net_device_stats *stats = &dev->dev->stats;
    unsigned long flags; 
    volatile pcsca_bd_t __iomem *ptdescr; 
    int i, nchar;
    int tosend = len;
    int nbuf = ((len - 1)/BD_DEF_LEN) + 1;
    unsigned char *pdata=buf;

    CPC_TTY_DBG("%s:cpc_tty_send_to_cars len=%i", 
            (st_cpc_tty_area *)dev->cpc_tty->name,len); 

    if (nbuf >= card->chan[ch].nfree_tx_bd) {
        return 1;
    }
    
    /* write buffer to DMA buffers */ 
    CPC_TTY_DBG("%s: call dma_buf_write\n",
            (st_cpc_tty_area *)dev->cpc_tty->name); 
    for (i = 0 ; i < nbuf ; i++) {
        ptdescr = (pcsca_bd_t __iomem *)(card->hw.rambase + 
            TX_BD_ADDR(ch, card->chan[ch].tx_next_bd));
        nchar = (BD_DEF_LEN > tosend) ? tosend : BD_DEF_LEN;
        if (cpc_readb(&ptdescr->status) & DST_OSB) {
            memcpy_toio((void __iomem *)(card->hw.rambase + 
                cpc_readl(&ptdescr->ptbuf)), 
                &pdata[len - tosend], 
                nchar);
            card->chan[ch].nfree_tx_bd--;
            if ((i + 1) == nbuf) {
                /* This must be the last BD to be used */
                cpc_writeb(&ptdescr->status, DST_EOM);
            } else {
                cpc_writeb(&ptdescr->status, 0);
            }
            cpc_writew(&ptdescr->len, nchar);
        } else {
            CPC_TTY_DBG("%s: error in dma_buf_write\n",
                    (st_cpc_tty_area *)dev->cpc_tty->name); 
            stats->tx_dropped++;
            return 1; 
        }
        tosend -= nchar;
        card->chan[ch].tx_next_bd = 
            (card->chan[ch].tx_next_bd + 1) & (N_DMA_TX_BUF - 1);
    }

    if (dev->trace_on) { 
        cpc_tty_trace(dev, buf, len,'T'); 
    }

    /* start transmission */ 
    CPC_TTY_DBG("%s: start transmission\n",
        (st_cpc_tty_area *)dev->cpc_tty->name); 
    
    CPC_TTY_LOCK(card, flags); 
    cpc_writeb(card->hw.scabase + DTX_REG(EDAL, ch), 
            TX_BD_ADDR(ch, chan->tx_next_bd)); 
    cpc_writeb(card->hw.scabase + M_REG(CMD, ch), CMD_TX_ENA); 
    cpc_writeb(card->hw.scabase + DSR_TX(ch), DSR_DE); 

    if (card->hw.type == PC300_TE) { 
        cpc_writeb(card->hw.falcbase + card->hw.cpld_reg2, 
            cpc_readb(card->hw.falcbase + card->hw.cpld_reg2) |
            (CPLD_REG2_FALC_LED1 << (2 * ch))); 
    }
    CPC_TTY_UNLOCK(card, flags); 
    return 0; 
} 

/*
 *  PC300 TTY trace routine
 *
 *  This routine send trace of connection to application. 
 *  o clear descriptors
 *  o write data to DMA buffers
 *  o start the transmission
 */

static void cpc_tty_trace(pc300dev_t *dev, char* buf, int len, char rxtx)
{
    struct sk_buff *skb; 

    if ((skb = dev_alloc_skb(10 + len)) == NULL) { 
        /* out of memory */ 
        CPC_TTY_DBG("%s: tty_trace - out of memory\n", dev->dev->name);
        return; 
    }

    skb_put (skb, 10 + len); 
    skb->dev = dev->dev; 
    skb->protocol = htons(ETH_P_CUST); 
    skb_reset_mac_header(skb);
    skb->pkt_type = PACKET_HOST; 
    skb->len = 10 + len; 

    skb_copy_to_linear_data(skb, dev->dev->name, 5);
    skb->data[5] = '['; 
    skb->data[6] = rxtx; 
    skb->data[7] = ']'; 
    skb->data[8] = ':'; 
    skb->data[9] = ' '; 
    skb_copy_to_linear_data_offset(skb, 10, buf, len);
    netif_rx(skb); 
}   

/*
 *  PC300 TTY unregister service routine
 *
 *  This routine unregister one interface. 
 */
void cpc_tty_unregister_service(pc300dev_t *pc300dev)
{
    st_cpc_tty_area *cpc_tty; 
    ulong flags;
    int res;

    if ((cpc_tty= (st_cpc_tty_area *) pc300dev->cpc_tty) == NULL) {
        CPC_TTY_DBG("%s: interface is not TTY\n", pc300dev->dev->name);
        return; 
    }
    CPC_TTY_DBG("%s: cpc_tty_unregister_service", cpc_tty->name);

    if (cpc_tty->pc300dev != pc300dev) { 
        CPC_TTY_DBG("%s: invalid tty ptr=%s\n", 
        pc300dev->dev->name, cpc_tty->name);
        return; 
    }

    if (--cpc_tty_cnt == 0) { 
        if (serial_drv.refcount) {
            CPC_TTY_DBG("%s: unregister is not possible, refcount=%d",
                            cpc_tty->name, serial_drv.refcount);
            cpc_tty_cnt++;
            cpc_tty_unreg_flag = 1;
            return;
        } else { 
            CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name);
            if ((res=tty_unregister_driver(&serial_drv))) { 
                CPC_TTY_DBG("%s: ERROR ->unregister the tty driver error=%d\n",
                                cpc_tty->name,res);
            }
        }
    }
    CPC_TTY_LOCK(pc300dev->chan->card,flags);
    cpc_tty->tty = NULL; 
    CPC_TTY_UNLOCK(pc300dev->chan->card, flags);
    cpc_tty->tty_minor = 0; 
    cpc_tty->state = CPC_TTY_ST_IDLE; 
} 

/*
 * PC300 TTY trigger poll routine
 * This routine is called by pc300driver to treats Tx interrupt. 
 */
void cpc_tty_trigger_poll(pc300dev_t *pc300dev)
{
    st_cpc_tty_area *cpc_tty = (st_cpc_tty_area *)pc300dev->cpc_tty; 
    if (!cpc_tty) {
        return;
    }
    schedule_work(&(cpc_tty->tty_tx_work)); 
}