/* Add an ARP-entry for this device's broadcast address. Not used. */
static void
sl_add_arp(unsigned long addr, struct sk_buff *skb, struct device *dev)
{
#ifdef CONFIG_AX25
	struct slip *sl=&sl_ctrl[dev->base_addr];
	
	if(sl->mode&SL_MODE_AX25)
		arp_add(addr,((char *) skb->data)+8,dev);
#endif		
}


/* Rebuild the MAC-level header.  Not used by SLIP. */
static int
sl_rebuild_header(void *buff, struct device *dev)
{
#ifdef CONFIG_AX25
  struct slip *sl=&sl_ctrl[dev->base_addr];
  
  if(sl->mode&SL_MODE_AX25)
  	return ax25_rebuild_header(buff,dev);
#endif  
  return(0);
}


/* Open the low-level part of the SLIP channel. Easy! */
static int
sl_open(struct device *dev)
{
  struct slip *sl;
  unsigned char *p;
  unsigned long l;

  sl = &sl_ctrl[dev->base_addr];
  if (sl->tty == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: channel %d not connected!\n", sl->line));
	return(-ENXIO);
  }
  sl->dev = dev;

  /*
   * Allocate the SLIP frame buffers:
   *
   * mem_end	Top of frame buffers
   * mem_start	Start of frame buffers
   * rmem_end	Top of RECV frame buffer
   * rmem_start	Start of RECV frame buffer
   */
  l = (dev->mtu * 2);
/*
 * allow for arrival of larger UDP packets, even if we say not to
 * also fixes a bug in which SunOS sends 512-byte packets even with
 * an MSS of 128
 */
  if (l < (576 * 2))
    l = 576 * 2;

  p = (unsigned char *) kmalloc(l + 4, GFP_KERNEL);
  if (p == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: no memory for SLIP XMIT buffer!\n"));
	return(-ENOMEM);
  }
  
  sl->mtu		= dev->mtu;
  sl->dev->mem_start	= (unsigned long) p;
  sl->dev->mem_end	= (unsigned long) (sl->dev->mem_start + l);

  p = (unsigned char *) kmalloc(l + 4, GFP_KERNEL);
  if (p == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: no memory for SLIP RECV buffer!\n"));
	return(-ENOMEM);
  }
  sl->dev->rmem_start	= (unsigned long) p;
  sl->dev->rmem_end	= (unsigned long) (sl->dev->rmem_start + l);

  sl->xbuff		= (unsigned char *) sl->dev->mem_start;
  sl->rbuff		= (unsigned char *) sl->dev->rmem_start;
  sl->rend		= (unsigned char *) sl->dev->rmem_end;
  sl->rhead		= sl->rbuff;

  sl->escape		= 0;
  sl->sending		= 0;
  sl->rcount		= 0;

  p = (unsigned char *) kmalloc(l + 4, GFP_KERNEL);
  if (p == NULL) {
  	kfree((unsigned char *)sl->dev->mem_start);
	DPRINTF((DBG_SLIP, "SLIP: no memory for SLIP COMPRESS buffer!\n"));
	return(-ENOMEM);
  }
  sl->cbuff		= p;

  sl->slcomp = slhc_init(16, 16);
  if (sl->slcomp == NULL) {
  	kfree((unsigned char *)sl->dev->mem_start);
  	kfree((unsigned char *)sl->dev->rmem_start);
  	kfree(sl->cbuff);
	DPRINTF((DBG_SLIP, "SLIP: no memory for SLCOMP!\n"));
	return(-ENOMEM);
  }

  dev->flags|=IFF_UP;
  /* Needed because address '0' is special */
  if(dev->pa_addr==0)
  	dev->pa_addr=ntohl(0xC0000001);
  DPRINTF((DBG_SLIP, "SLIP: channel %d opened.\n", sl->line));
  return(0);
}


/* Close the low-level part of the SLIP channel. Easy! */
static int
sl_close(struct device *dev)
{
  struct slip *sl;

  sl = &sl_ctrl[dev->base_addr];
  if (sl->tty == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: channel %d not connected!\n", sl->line));
	return(-EBUSY);
  }
  sl_free(sl);

  /* Free all SLIP frame buffers. */
  kfree(sl->rbuff);
  kfree(sl->xbuff);
  kfree(sl->cbuff);
  slhc_free(sl->slcomp);

  sl_initialize(sl, dev);

  DPRINTF((DBG_SLIP, "SLIP: channel %d closed.\n", sl->line));
  return(0);
}


/*
 * Handle the 'receiver data ready' interrupt.
 * This function is called by the 'tty_io' module in the kernel when
 * a block of SLIP data has been received, which can now be decapsulated
 * and sent on to some IP layer for further processing.
 */
static void
slip_recv(struct tty_struct *tty)
{
  unsigned char buff[128];
  unsigned char *p;
  struct slip *sl;
  int count, error=0;
  
  DPRINTF((DBG_SLIP, "SLIP: slip_recv(%d) called\n", tty->line));
  if ((sl = sl_find(tty)) == NULL) return;	/* not connected */

  if(sl->mtu!=sl->dev->mtu)	/* Argh! mtu change time! - costs us the packet part received at the change */
  	sl_changedmtu(sl);
  	
  /* Suck the bytes out of the TTY queues. */
  do {
	count = tty_read_raw_data(tty, buff, 128);
	if (count <= 0)
	{
		count= - count;
		if(count)
			error=1;
		break;
	}
	p = buff;
#ifdef OLD	
	while (count--) {
		c = *p++;
		if (sl->escape) {
			if (c == ESC_ESC)
				sl_enqueue(sl, ESC);
			else if (c == ESC_END)
				sl_enqueue(sl, END);
			else
				printk ("SLIP: received wrong character\n");
			sl->escape = 0;
		} else {
			if (c == ESC)
				sl->escape = 1;
			else if (c == END) {
				if (sl->rcount > 2) sl_bump(sl);
				sl_dequeue(sl, sl->rcount);
				sl->rcount = 0;
			} else	sl_enqueue(sl, c);
		}
	}
#else
	if(sl->mode & SL_MODE_SLIP6)
		slip_unesc6(sl,buff,count,error);
	else
		slip_unesc(sl,buff,count,error);
#endif		
  } while(1);
  
}


/*
 * Open the high-level part of the SLIP channel.  
 * This function is called by the TTY module when the
 * SLIP line discipline is called for.  Because we are
 * sure the tty line exists, we only have to link it to
 * a free SLIP channel...
 */
static int
slip_open(struct tty_struct *tty)
{
  struct slip *sl;

  /* First make sure we're not already connected. */
  if ((sl = sl_find(tty)) != NULL) {
	DPRINTF((DBG_SLIP, "SLIP: TTY %d already connected to %s !\n",
					tty->line, sl->dev->name));
	return(-EEXIST);
  }

  /* OK.  Find a free SLIP channel to use. */
  if ((sl = sl_alloc()) == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: TTY %d not connected: all channels in use!\n",
						tty->line));
	return(-ENFILE);
  }
  sl->tty = tty;
  tty_read_flush(tty);
  tty_write_flush(tty);

  /* Perform the low-level SLIP initialization. */
  (void) sl_open(sl->dev);
  DPRINTF((DBG_SLIP, "SLIP: TTY %d connected to %s.\n",
				tty->line, sl->dev->name));

  /* Done.  We have linked the TTY line to a channel. */
  return(sl->line);
}

 
static struct enet_statistics *
sl_get_stats(struct device *dev)
{
    static struct enet_statistics stats;
    struct slip *sl;
    struct slcompress *comp;

    /* Find the correct SLIP channel to use. */
    sl = &sl_ctrl[dev->base_addr];
    if (! sl)
      return NULL;

    memset(&stats, 0, sizeof(struct enet_statistics));

    stats.rx_packets = sl->rpacket;
    stats.rx_over_errors = sl->roverrun;
    stats.tx_packets = sl->spacket;
    stats.tx_dropped = sl->sbusy;
    stats.rx_errors = sl->errors;

    comp = sl->slcomp;
    if (comp) {
      stats.rx_fifo_errors = comp->sls_i_compressed;
      stats.rx_dropped = comp->sls_i_tossed;
      stats.tx_fifo_errors = comp->sls_o_compressed;
      stats.collisions = comp->sls_o_misses;
    }

    return (&stats);
}

/*
 * Close down a SLIP channel.
 * This means flushing out any pending queues, and then restoring the
 * TTY line discipline to what it was before it got hooked to SLIP
 * (which usually is TTY again).
 */
static void
slip_close(struct tty_struct *tty)
{
  struct slip *sl;

  /* First make sure we're connected. */
  if ((sl = sl_find(tty)) == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: TTY %d not connected !\n", tty->line));
	return;
  }

  (void) dev_close(sl->dev);
  DPRINTF((DBG_SLIP, "SLIP: TTY %d disconnected from %s.\n",
					tty->line, sl->dev->name));
}

 
 /************************************************************************
  *			STANDARD SLIP ENCAPSULATION			*
  ************************************************************************
  *
  */
 
 int
 slip_esc(unsigned char *s, unsigned char *d, int len)
 {
     int count = 0;
 
     /*
      * Send an initial END character to flush out any
      * data that may have accumulated in the receiver
      * due to line noise.
      */
 
     d[count++] = END;
 
     /*
      * For each byte in the packet, send the appropriate
      * character sequence, according to the SLIP protocol.
      */
 
     while(len-- > 0) {
     	switch(*s) {
     	case END:
     	    d[count++] = ESC;
     	    d[count++] = ESC_END;
 	    break;
 	case ESC:
     	    d[count++] = ESC;
     	    d[count++] = ESC_ESC;
 	    break;
 	default:
 	    d[count++] = *s;
 	}
 	++s;
     }
     d[count++] = END;
     return(count);
 }
 
 void
 slip_unesc(struct slip *sl, unsigned char *s, int count, int error)
 {
     int i;
 
     for (i = 0; i < count; ++i, ++s) {
 	switch(*s) {
 	case ESC:
 	    sl->flags |= SLF_ESCAPE;
 	    break;
 	case ESC_ESC:
 	    if (sl->flags & SLF_ESCAPE)
 	    	sl_enqueue(sl, ESC);
 	    else
 	        sl_enqueue(sl, *s);
	    sl->flags &= ~SLF_ESCAPE;
 	    break;
	case ESC_END:
 	    if (sl->flags & SLF_ESCAPE)
	    	sl_enqueue(sl, END);
	    else
 	        sl_enqueue(sl, *s);
	    sl->flags &= ~SLF_ESCAPE;
	    break;
	case END:
 	    if (sl->rcount > 2) 
 	    	sl_bump(sl);
 	    sl_dequeue(sl, sl->rcount);
 	    sl->rcount = 0;
 	    sl->flags &= ~(SLF_ESCAPE | SLF_ERROR);
 	    break;
 	default:
 	    sl_enqueue(sl, *s);
 	    sl->flags &= ~SLF_ESCAPE;
 	}
     }
     if (error)
     	sl->flags |= SLF_ERROR;
 }
 
 /************************************************************************
  *			 6 BIT SLIP ENCAPSULATION			*
  ************************************************************************
  *
  */
 
 int
 slip_esc6(unsigned char *s, unsigned char *d, int len)
 {
     int count = 0;
     int i;
     unsigned short v = 0;
     short bits = 0;
 
     /*
      * Send an initial END character to flush out any
      * data that may have accumulated in the receiver
      * due to line noise.
      */
 
     d[count++] = 0x70;
 
     /*
      * Encode the packet into printable ascii characters
      */
 
     for (i = 0; i < len; ++i) {
     	v = (v << 8) | s[i];
     	bits += 8;
     	while (bits >= 6) {
     	    unsigned char c;
 
     	    bits -= 6;
     	    c = 0x30 + ((v >> bits) & 0x3F);
     	    d[count++] = c;
 	}
     }
     if (bits) {
     	unsigned char c;
 
     	c = 0x30 + ((v << (6 - bits)) & 0x3F);
     	d[count++] = c;
     }
     d[count++] = 0x70;
     return(count);
 }
 
 void
 slip_unesc6(struct slip *sl, unsigned char *s, int count, int error)
 {
     int i;
     unsigned char c;
 
     for (i = 0; i < count; ++i, ++s) {
     	if (*s == 0x70) {
 	    if (sl->rcount > 8) {	/* XXX must be 2 for compressed slip */
 #ifdef NOTDEF
 	        printk("rbuff %02x %02x %02x %02x\n",
 	            sl->rbuff[0],
 	            sl->rbuff[1],
 	            sl->rbuff[2],
 	            sl->rbuff[3]
 	        );
 #endif
 	    	sl_bump(sl);
 	    }
 	    sl_dequeue(sl, sl->rcount);
 	    sl->rcount = 0;
 	    sl->flags &= ~(SLF_ESCAPE | SLF_ERROR); /* SLF_ESCAPE not used */
 	    sl->xbits = 0;
 	} else if (*s >= 0x30 && *s < 0x70) {
 	    sl->xdata = (sl->xdata << 6) | ((*s - 0x30) & 0x3F);
 	    sl->xbits += 6;
 	    if (sl->xbits >= 8) {
 	    	sl->xbits -= 8;
 	    	c = (unsigned char)(sl->xdata >> sl->xbits);
 		sl_enqueue(sl, c);
 	    }
 
 	}
     }
     if (error)
     	sl->flags |= SLF_ERROR;
 }


#ifdef CONFIG_AX25

int sl_set_mac_address(struct device *dev, void *addr)
{
	int err=verify_area(VERIFY_READ,addr,7);
	if(err)
		return err;
	memcpy_fromfs(dev->dev_addr,addr,7);	/* addr is an AX.25 shifted ASCII mac address */
	return 0;
}
#endif


/* Perform I/O control on an active SLIP channel. */
static int
slip_ioctl(struct tty_struct *tty, void *file, int cmd, void *arg)
{
  struct slip *sl;
  int err;

  /* First make sure we're connected. */
  if ((sl = sl_find(tty)) == NULL) {
	DPRINTF((DBG_SLIP, "SLIP: ioctl: TTY %d not connected !\n", tty->line));
	return(-EINVAL);
  }

  DPRINTF((DBG_SLIP, "SLIP: ioctl(%d, 0x%X, 0x%X)\n", tty->line, cmd, arg));
  switch(cmd) {
	case SIOCGIFNAME:
		err=verify_area(VERIFY_WRITE, arg, 16);
		if(err)
			return -err;
		memcpy_tofs(arg, sl->dev->name, strlen(sl->dev->name) + 1);
		return(0);
	case SIOCGIFENCAP:
		err=verify_area(VERIFY_WRITE,arg,sizeof(long));
		put_fs_long(sl->mode,(long *)arg);
		return(0);
	case SIOCSIFENCAP:
		err=verify_area(VERIFY_READ,arg,sizeof(long));
		sl->mode=get_fs_long((long *)arg);
#ifdef CONFIG_AX25		
		if(sl->mode & SL_MODE_AX25)
		{
			sl->dev->addr_len=7;	/* sizeof an AX.25 addr */
			sl->dev->hard_header_len=17;	/* We don't do digipeaters */
			sl->dev->type=3;		/* AF_AX25 not an AF_INET device */
		}
		else
		{
			sl->dev->addr_len=0;	/* No mac addr in slip mode */
			sl->dev->hard_header_len=0;
			sl->dev->type=0;
		}
#endif		
		return(0);
	case SIOCSIFHWADDR:
#ifdef CONFIG_AX25	
		return sl_set_mac_address(sl->dev,arg);
#endif
	default:
		return(-EINVAL);
  }
  return(-EINVAL);
}


/* Initialize the SLIP driver.  Called by DDI. */
int
slip_init(struct device *dev)
{
  struct slip *sl;
  int i;
#ifdef CONFIG_AX25  
  static char ax25_bcast[7]={'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
  static char ax25_test[7]={'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};
#endif

  sl = &sl_ctrl[dev->base_addr];

  if (already++ == 0) {
	printk("SLIP: version %s (%d channels)\n",
				SLIP_VERSION, SL_NRUNIT);
	printk("CSLIP: code copyright 1989 Regents of the University of California\n");
#ifdef CONFIG_AX25
	printk("AX25: KISS encapsulation enabled\n");
#endif	
	/* Fill in our LDISC request block. */
	sl_ldisc.flags	= 0;
	sl_ldisc.open	= slip_open;
	sl_ldisc.close	= slip_close;
	sl_ldisc.read	= NULL;
	sl_ldisc.write	= NULL;
	sl_ldisc.ioctl	= (int (*)(struct tty_struct *, struct file *,
				   unsigned int, unsigned long)) slip_ioctl;
	sl_ldisc.select = NULL;
	sl_ldisc.handler = slip_recv;
	if ((i = tty_register_ldisc(N_SLIP, &sl_ldisc)) != 0)
		printk("ERROR: %d\n", i);
  }

  /* Set up the "SLIP Control Block". */
  sl_initialize(sl, dev);

  /* Clear all statistics. */
  sl->rcount		= 0;			/* SLIP receiver count	*/
  sl->rpacket		= 0;			/* #frames received	*/
  sl->roverrun		= 0;			/* "overrun" counter	*/
  sl->spacket		= 0;			/* #frames sent out	*/
  sl->sbusy		= 0;			/* "xmit busy" counter	*/
  sl->errors		= 0;			/* not used at present	*/

  /* Finish setting up the DEVICE info. */
  dev->mtu		= SL_MTU;
  dev->hard_start_xmit	= sl_xmit;
  dev->open		= sl_open;
  dev->stop		= sl_close;
  dev->hard_header	= sl_header;
  dev->add_arp		= sl_add_arp;
  dev->type_trans	= sl_type_trans;
  dev->get_stats	= sl_get_stats;
#ifdef HAVE_SET_MAC_ADDR
#ifdef CONFIG_AX25
  dev->set_mac_address  = sl_set_mac_address;
#endif
#endif
  dev->hard_header_len	= 0;
  dev->addr_len		= 0;
  dev->type		= 0;
#ifdef CONFIG_AX25  
  memcpy(dev->broadcast,ax25_bcast,7);		/* Only activated in AX.25 mode */
  memcpy(dev->dev_addr,ax25_test,7);		/*    ""      ""       ""    "" */
#endif  
  dev->queue_xmit	= dev_queue_xmit;
  dev->rebuild_header	= sl_rebuild_header;
  for (i = 0; i < DEV_NUMBUFFS; i++)
		dev->buffs[i] = NULL;

  /* New-style flags. */
  dev->flags		= 0;
  dev->family		= AF_INET;
  dev->pa_addr		= 0;
  dev->pa_brdaddr	= 0;
  dev->pa_mask		= 0;
  dev->pa_alen		= sizeof(unsigned long);

  return(0);
}