/*
 * pc300_tty.c  Cyclades-PC300(tm) TTY Driver.
 *
 * Author:      Regina Kodato <reginak@cyclades.com>
 *
 * 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)); 
}