text: /* $Id: isdnloop.c,v 1.1.1.4 2003/10/14 08:08:13 sparq Exp $
   *
   * ISDN low-level module implementing a dummy loop driver.
   *
   * Copyright 1997 by Fritz Elfert (fritz@isdn4linux.de)
   *
   * This software may be used and distributed according to the terms
   * of the GNU General Public License, incorporated herein by reference.
   *
   */
  
  #include <linux/config.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include "isdnloop.h"
  
  static char *revision = "$Revision: 1.1.1.4 $";
  static char *isdnloop_id;
  
  MODULE_DESCRIPTION("ISDN4Linux: Pseudo Driver that simulates an ISDN card");
  MODULE_AUTHOR("Fritz Elfert");
  MODULE_LICENSE("GPL");
  MODULE_PARM(isdnloop_id, "s");
  MODULE_PARM_DESC(isdnloop_id, "ID-String of first card");
  
  static int isdnloop_addcard(char *);
  
  /*
   * Free queue completely.
   *
   * Parameter:
   *   card    = pointer to card struct
   *   channel = channel number
   */
  static void
  isdnloop_free_queue(isdnloop_card * card, int channel)
  {
  	struct sk_buff_head *queue = &card->bqueue[channel];
  
  	skb_queue_purge(queue);
  	card->sndcount[channel] = 0;
  }
  
  /*
   * Send B-Channel data to another virtual card.
   * This routine is called via timer-callback from isdnloop_pollbchan().
   *
   * Parameter:
   *   card = pointer to card struct.
   *   ch   = channel number (0-based)
   */
  static void
  isdnloop_bchan_send(isdnloop_card * card, int ch)
  {
  	isdnloop_card *rcard = card->rcard[ch];
  	int rch = card->rch[ch], len, ack;
  	struct sk_buff *skb;
  	isdn_ctrl cmd;
  
  	while (card->sndcount[ch]) {
  		if ((skb = skb_dequeue(&card->bqueue[ch]))) {
  			len = skb->len;
  			card->sndcount[ch] -= len;
  			ack = *(skb->head); /* used as scratch area */
  			cmd.driver = card->myid;
  			cmd.arg = ch;
  			if (rcard){
  				rcard->interface.rcvcallb_skb(rcard->myid, rch, skb);
  			} else {
  				printk(KERN_WARNING "isdnloop: no rcard, skb dropped\n");
  				dev_kfree_skb(skb);
  
  				cmd.command = ISDN_STAT_L1ERR;
  				cmd.parm.errcode = ISDN_STAT_L1ERR_SEND;
  				card->interface.statcallb(&cmd); 
  			};
  			cmd.command = ISDN_STAT_BSENT;
  			cmd.parm.length = len;
  			if ( ack ) card->interface.statcallb(&cmd);
  		} else
  			card->sndcount[ch] = 0;
  	}
  }
  
  /*
   * Send/Receive Data to/from the B-Channel.
   * This routine is called via timer-callback.
   * It schedules itself while any B-Channel is open.
   *
   * Parameter:
   *   data = pointer to card struct, set by kernel timer.data
   */
  static void
  isdnloop_pollbchan(unsigned long data)
  {
  	isdnloop_card *card = (isdnloop_card *) data;
  	unsigned long flags;
  
  	if (card->flags & ISDNLOOP_FLAGS_B1ACTIVE)
  		isdnloop_bchan_send(card, 0);
  	if (card->flags & ISDNLOOP_FLAGS_B2ACTIVE)
  		isdnloop_bchan_send(card, 1);
  	if (card->flags & (ISDNLOOP_FLAGS_B1ACTIVE | ISDNLOOP_FLAGS_B2ACTIVE)) {
  		/* schedule b-channel polling again */
  		save_flags(flags);
  		cli();
  		card->rb_timer.expires = jiffies + ISDNLOOP_TIMER_BCREAD;
  		add_timer(&card->rb_timer);
  		card->flags |= ISDNLOOP_FLAGS_RBTIMER;
  		restore_flags(flags);
  	} else
  		card->flags &= ~ISDNLOOP_FLAGS_RBTIMER;
  }
  
  /*
   * Parse ICN-type setup string and fill fields of setup-struct
   * with parsed data.
   *
   * Parameter:
   *   setup = setup string, format: [caller-id],si1,si2,[called-id]
   *   cmd   = pointer to struct to be filled.
   */
  static void
  isdnloop_parse_setup(char *setup, isdn_ctrl * cmd)
  {
  	char *t = setup;
  	char *s = strpbrk(t, ",");
  
  	*s++ = '\0';
  	strncpy(cmd->parm.setup.phone, t, sizeof(cmd->parm.setup.phone));
  	s = strpbrk(t = s, ",");
  	*s++ = '\0';
  	if (!strlen(t))
  		cmd->parm.setup.si1 = 0;
  	else
  		cmd->parm.setup.si1 = simple_strtoul(t, NULL, 10);
  	s = strpbrk(t = s, ",");
  	*s++ = '\0';
  	if (!strlen(t))
  		cmd->parm.setup.si2 = 0;
  	else
  		cmd->parm.setup.si2 =
  		    simple_strtoul(t, NULL, 10);
  	strncpy(cmd->parm.setup.eazmsn, s, sizeof(cmd->parm.setup.eazmsn));
  	cmd->parm.setup.plan = 0;
  	cmd->parm.setup.screen = 0;
  }
  
  typedef struct isdnloop_stat {
  	char *statstr;
  	int command;
  	int action;
  } isdnloop_stat;
  /* *INDENT-OFF* */
  static isdnloop_stat isdnloop_stat_table[] =
  {
  	{"BCON_",          ISDN_STAT_BCONN, 1}, /* B-Channel connected        */
  	{"BDIS_",          ISDN_STAT_BHUP,  2}, /* B-Channel disconnected     */
  	{"DCON_",          ISDN_STAT_DCONN, 0}, /* D-Channel connected        */
  	{"DDIS_",          ISDN_STAT_DHUP,  0}, /* D-Channel disconnected     */
  	{"DCAL_I",         ISDN_STAT_ICALL, 3}, /* Incoming call dialup-line  */
  	{"DSCA_I",         ISDN_STAT_ICALL, 3}, /* Incoming call 1TR6-SPV     */
  	{"FCALL",          ISDN_STAT_ICALL, 4}, /* Leased line connection up  */
  	{"CIF",            ISDN_STAT_CINF,  5}, /* Charge-info, 1TR6-type     */
  	{"AOC",            ISDN_STAT_CINF,  6}, /* Charge-info, DSS1-type     */
  	{"CAU",            ISDN_STAT_CAUSE, 7}, /* Cause code                 */
  	{"TEI OK",         ISDN_STAT_RUN,   0}, /* Card connected to wallplug */
  	{"NO D-CHAN",      ISDN_STAT_NODCH, 0}, /* No D-channel available     */
  	{"E_L1: ACT FAIL", ISDN_STAT_BHUP,  8}, /* Layer-1 activation failed  */
  	{"E_L2: DATA LIN", ISDN_STAT_BHUP,  8}, /* Layer-2 data link lost     */
  	{"E_L1: ACTIVATION FAILED",
  			   ISDN_STAT_BHUP,  8},         /* Layer-1 activation failed  */
  	{NULL, 0, -1}
  };
  /* *INDENT-ON* */
  
  
  /*
   * Parse Status message-strings from virtual card.
   * Depending on status, call statcallb for sending messages to upper
   * levels. Also set/reset B-Channel active-flags.
   *
   * Parameter:
   *   status  = status string to parse.
   *   channel = channel where message comes from.
   *   card    = card where message comes from.
   */
  static void
  isdnloop_parse_status(u_char * status, int channel, isdnloop_card * card)
  {
  	isdnloop_stat *s = isdnloop_stat_table;
  	int action = -1;
  	isdn_ctrl cmd;
  
  	while (s->statstr) {
  		if (!strncmp(status, s->statstr, strlen(s->statstr))) {
  			cmd.command = s->command;
  			action = s->action;
  			break;
  		}
  		s++;
  	}
  	if (action == -1)
  		return;
  	cmd.driver = card->myid;
  	cmd.arg = channel;
  	switch (action) {
  		case 1:
  			/* BCON_x */
  			card->flags |= (channel) ?
  			    ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE;
  			break;
  		case 2:
  			/* BDIS_x */
  			card->flags &= ~((channel) ?
  					 ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE);
  			isdnloop_free_queue(card, channel);
  			break;
  		case 3:
  			/* DCAL_I and DSCA_I */
  			isdnloop_parse_setup(status + 6, &cmd);
  			break;
  		case 4:
  			/* FCALL */
  			sprintf(cmd.parm.setup.phone, "LEASED%d", card->myid);
  			sprintf(cmd.parm.setup.eazmsn, "%d", channel + 1);
  			cmd.parm.setup.si1 = 7;
  			cmd.parm.setup.si2 = 0;
  			cmd.parm.setup.plan = 0;
  			cmd.parm.setup.screen = 0;
  			break;
  		case 5:
  			/* CIF */
  			strncpy(cmd.parm.num, status + 3, sizeof(cmd.parm.num) - 1);
  			break;
  		case 6:
  			/* AOC */
  			sprintf(cmd.parm.num, "%d",
  			     (int) simple_strtoul(status + 7, NULL, 16));
  			break;
  		case 7:
  			/* CAU */
  			status += 3;
  			if (strlen(status) == 4)
  				sprintf(cmd.parm.num, "%s%c%c",
  				     status + 2, *status, *(status + 1));
  			else
  				strncpy(cmd.parm.num, status + 1, sizeof(cmd.parm.num) - 1);
  			break;
  		case 8:
  			/* Misc Errors on L1 and L2 */
  			card->flags &= ~ISDNLOOP_FLAGS_B1ACTIVE;
  			isdnloop_free_queue(card, 0);
  			cmd.arg = 0;
  			cmd.driver = card->myid;
  			card->interface.statcallb(&cmd);
  			cmd.command = ISDN_STAT_DHUP;
  			cmd.arg = 0;
  			cmd.driver = card->myid;
  			card->interface.statcallb(&cmd);
  			cmd.command = ISDN_STAT_BHUP;
  			card->flags &= ~ISDNLOOP_FLAGS_B2ACTIVE;
  			isdnloop_free_queue(card, 1);
  			cmd.arg = 1;
  			cmd.driver = card->myid;
  			card->interface.statcallb(&cmd);
  			cmd.command = ISDN_STAT_DHUP;
  			cmd.arg = 1;
  			cmd.driver = card->myid;
  			break;
  	}
  	card->interface.statcallb(&cmd);
  }
  
  /*
   * Store a cwcharacter into ringbuffer for reading from /dev/isdnctrl
   *
   * Parameter:
   *   card = pointer to card struct.
   *   c    = char to store.
   */
  static void
  isdnloop_putmsg(isdnloop_card * card, unsigned char c)
  {
  	ulong flags;
  
  	save_flags(flags);
  	cli();
  	*card->msg_buf_write++ = (c == 0xff) ? '\n' : c;
  	if (card->msg_buf_write == card->msg_buf_read) {
  		if (++card->msg_buf_read > card->msg_buf_end)
  			card->msg_buf_read = card->msg_buf;
  	}
  	if (card->msg_buf_write > card->msg_buf_end)
  		card->msg_buf_write = card->msg_buf;
  	restore_flags(flags);
  }
  
  /*
   * Poll a virtual cards message queue.
   * If there are new status-replies from the card, copy them to
   * ringbuffer for reading on /dev/isdnctrl and call
   * isdnloop_parse_status() for processing them. Watch for special
   * Firmware bootmessage and parse it, to get the D-Channel protocol.
   * If there are B-Channels open, initiate a timer-callback to
   * isdnloop_pollbchan().
   * This routine is called periodically via timer interrupt.
   *
   * Parameter:
   *   data = pointer to card struct
   */
  static void
  isdnloop_polldchan(unsigned long data)
  {
  	isdnloop_card *card = (isdnloop_card *) data;
  	struct sk_buff *skb;
  	int avail;
  	int left;
  	u_char c;
  	int ch;
  	unsigned long flags;
  	u_char *p;
  	isdn_ctrl cmd;
  
  	if ((skb = skb_dequeue(&card->dqueue)))
  		avail = skb->len;
  	else
  		avail = 0;
  	for (left = avail; left > 0; left--) {
  		c = *skb->data;
  		skb_pull(skb, 1);
  		isdnloop_putmsg(card, c);
  		card->imsg[card->iptr] = c;
  		if (card->iptr < 59)
  			card->iptr++;
  		if (!skb->len) {
  			avail++;
  			isdnloop_putmsg(card, '\n');
  			card->imsg[card->iptr] = 0;
  			card->iptr = 0;
  			if (card->imsg[0] == '0' && card->imsg[1] >= '0' &&
  			  card->imsg[1] <= '2' && card->imsg[2] == ';') {
  				ch = (card->imsg[1] - '0') - 1;
  				p = &card->imsg[3];
  				isdnloop_parse_status(p, ch, card);
  			} else {
  				p = card->imsg;
  				if (!strncmp(p, "DRV1.", 5)) {
  					printk(KERN_INFO "isdnloop: (%s) %s\n", CID, p);
  					if (!strncmp(p + 7, "TC", 2)) {
  						card->ptype = ISDN_PTYPE_1TR6;
  						card->interface.features |= ISDN_FEATURE_P_1TR6;
  						printk(KERN_INFO
  						       "isdnloop: (%s) 1TR6-Protocol loaded and running\n", CID);
  					}
  					if (!strncmp(p + 7, "EC", 2)) {
  						card->ptype = ISDN_PTYPE_EURO;
  						card->interface.features |= ISDN_FEATURE_P_EURO;
  						printk(KERN_INFO
  						       "isdnloop: (%s) Euro-Protocol loaded and running\n", CID);
  					}
  					continue;
  
  				}
  			}
  		}
  	}
  	if (avail) {
  		cmd.command = ISDN_STAT_STAVAIL;
  		cmd.driver = card->myid;
  		cmd.arg = avail;
  		card->interface.statcallb(&cmd);
  	}
  	if (card->flags & (ISDNLOOP_FLAGS_B1ACTIVE | ISDNLOOP_FLAGS_B2ACTIVE))
  		if (!(card->flags & ISDNLOOP_FLAGS_RBTIMER)) {
  			/* schedule b-channel polling */
  			card->flags |= ISDNLOOP_FLAGS_RBTIMER;
  			save_flags(flags);
  			cli();
  			del_timer(&card->rb_timer);
  			card->rb_timer.function = isdnloop_pollbchan;
  			card->rb_timer.data = (unsigned long) card;
  			card->rb_timer.expires = jiffies + ISDNLOOP_TIMER_BCREAD;
  			add_timer(&card->rb_timer);
  			restore_flags(flags);
  		}
  	/* schedule again */
  	save_flags(flags);
  	cli();
  	card->st_timer.expires = jiffies + ISDNLOOP_TIMER_DCREAD;
  	add_timer(&card->st_timer);
  	restore_flags(flags);
  }
  
  /*
   * Append a packet to the transmit buffer-queue.
   *
   * Parameter:
   *   channel = Number of B-channel
   *   skb     = packet to send.
   *   card    = pointer to card-struct
   * Return:
   *   Number of bytes transferred, -E??? on error
   */
  static int
  isdnloop_sendbuf(int channel, struct sk_buff *skb, isdnloop_card * card)
  {
  	int len = skb->len;
  	unsigned long flags;
  	struct sk_buff *nskb;
  
  	if (len > 4000) {
  		printk(KERN_WARNING
  		       "isdnloop: Send packet too large\n");
  		return -EINVAL;
  	}
  	if (len) {
  		if (!(card->flags & (channel) ? ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE))
  			return 0;
  		if (card->sndcount[channel] > ISDNLOOP_MAX_SQUEUE)
  			return 0;
  		save_flags(flags);
  		cli();
  		nskb = skb_clone(skb, GFP_ATOMIC);
  		if (nskb) {
  			skb_queue_tail(&card->bqueue[channel], nskb);
  			dev_kfree_skb(skb);
  		} else
  			len = 0;
  		card->sndcount[channel] += len;
  		restore_flags(flags);
  	}
  	return len;
  }
  
  /*
   * Read the messages from the card's ringbuffer
   *
   * Parameter:
   *   buf  = pointer to buffer.
   *   len  = number of bytes to read.
   *   user = flag, 1: called from userlevel 0: called from kernel.
   *   card = pointer to card struct.
   * Return:
   *   number of bytes actually transferred.
   */
  static int
  isdnloop_readstatus(u_char * buf, int len, int user, isdnloop_card * card)
  {
  	int count;
  	u_char *p;
  
  	for (p = buf, count = 0; count < len; p++, count++) {
  		if (card->msg_buf_read == card->msg_buf_write)
  			return count;
  		if (user)
  			put_user(*card->msg_buf_read++, p);
  		else
  			*p = *card->msg_buf_read++;
  		if (card->msg_buf_read > card->msg_buf_end)
  			card->msg_buf_read = card->msg_buf;
  	}
  	return count;
  }
  
  /*
   * Simulate a card's response by appending it to the cards
   * message queue.
   *
   * Parameter:
   *   card = pointer to card struct.
   *   s    = pointer to message-string.
   *   ch   = channel: 0 = generic messages, 1 and 2 = D-channel messages.
   * Return:
   *   0 on success, 1 on memory squeeze.
   */
  static int
  isdnloop_fake(isdnloop_card * card, char *s, int ch)
  {
  	struct sk_buff *skb;
  	int len = strlen(s) + ((ch >= 0) ? 3 : 0);
  
  	if (!(skb = dev_alloc_skb(len))) {
  		printk(KERN_WARNING "isdnloop: Out of memory in isdnloop_fake\n");
  		return 1;
  	}
  	if (ch >= 0)
  		sprintf(skb_put(skb, 3), "%02d;", ch);
  	memcpy(skb_put(skb, strlen(s)), s, strlen(s));
  	skb_queue_tail(&card->dqueue, skb);
  	return 0;
  }
  /* *INDENT-OFF* */
  static isdnloop_stat isdnloop_cmd_table[] =
  {
  	{"BCON_R",         0,  1},	/* B-Channel connect        */
  	{"BCON_I",         0, 17},	/* B-Channel connect ind    */
  	{"BDIS_R",         0,  2},	/* B-Channel disconnect     */
  	{"DDIS_R",         0,  3},	/* D-Channel disconnect     */
  	{"DCON_R",         0, 16},	/* D-Channel connect        */
  	{"DSCA_R",         0,  4},	/* Dial 1TR6-SPV     */
  	{"DCAL_R",         0,  5},	/* Dial */
  	{"EAZC",           0,  6},	/* Clear EAZ listener */
  	{"EAZ",            0,  7},	/* Set EAZ listener */
  	{"SEEAZ",          0,  8},	/* Get EAZ listener */
  	{"MSN",            0,  9},	/* Set/Clear MSN listener */
  	{"MSALL",          0, 10},	/* Set multi MSN listeners */
  	{"SETSIL",         0, 11},	/* Set SI list     */
  	{"SEESIL",         0, 12},	/* Get SI list     */
  	{"SILC",           0, 13},	/* Clear SI list     */
  	{"LOCK",           0, -1},	/* LOCK channel     */
  	{"UNLOCK",         0, -1},	/* UNLOCK channel     */
  	{"FV2ON",          1, 14},	/* Leased mode on               */
  	{"FV2OFF",         1, 15},	/* Leased mode off              */
  	{NULL, 0, -1}
  };
  /* *INDENT-ON* */
  
  
  /*
   * Simulate an error-response from a card.
   *
   * Parameter:
   *   card = pointer to card struct.
   */
  static void
  isdnloop_fake_err(isdnloop_card * card)
  {
  	char buf[60];
  
  	sprintf(buf, "E%s", card->omsg);
  	isdnloop_fake(card, buf, -1);
  	isdnloop_fake(card, "NAK", -1);
  }
  
  static u_char ctable_eu[] =
  {0x00, 0x11, 0x01, 0x12};
  static u_char ctable_1t[] =
  {0x00, 0x3b, 0x01, 0x3a};
  
  /*
   * Assemble a simplified cause message depending on the
   * D-channel protocol used.
   *
   * Parameter:
   *   card = pointer to card struct.
   *   loc  = location: 0 = local, 1 = remote.
   *   cau  = cause: 1 = busy, 2 = nonexistent callerid, 3 = no user responding.
   * Return:
   *   Pointer to buffer containing the assembled message.
   */
  static char *
  isdnloop_unicause(isdnloop_card * card, int loc, int cau)
  {
  	static char buf[6];
  
  	switch (card->ptype) {
  		case ISDN_PTYPE_EURO:
  			sprintf(buf, "E%02X%02X", (loc) ? 4 : 2, ctable_eu[cau]);
  			break;
  		case ISDN_PTYPE_1TR6:
  			sprintf(buf, "%02X44", ctable_1t[cau]);
  			break;
  		default:
  			return ("0000");
  	}
  	return (buf);
  }
  
  /*
   * Release a virtual connection. Called from timer interrupt, when
   * called party did not respond.
   *
   * Parameter:
   *   card = pointer to card struct.
   *   ch   = channel (0-based)
   */
  static void
  isdnloop_atimeout(isdnloop_card * card, int ch)
  {
  	unsigned long flags;
  	char buf[60];
  
  	save_flags(flags);
  	cli();
  	if (card->rcard) {
  		isdnloop_fake(card->rcard[ch], "DDIS_I", card->rch[ch] + 1);
  		card->rcard[ch]->rcard[card->rch[ch]] = NULL;
  		card->rcard[ch] = NULL;
  	}
  	isdnloop_fake(card, "DDIS_I", ch + 1);
  	/* No user responding */
  	sprintf(buf, "CAU%s", isdnloop_unicause(card, 1, 3));
  	isdnloop_fake(card, buf, ch + 1);
  	restore_flags(flags);
  }
  
  /*
   * Wrapper for isdnloop_atimeout().
   */
  static void
  isdnloop_atimeout0(unsigned long data)
  {
  	isdnloop_card *card = (isdnloop_card *) data;
  	isdnloop_atimeout(card, 0);
  }
  
  /*
   * Wrapper for isdnloop_atimeout().
   */
  static void
  isdnloop_atimeout1(unsigned long data)
  {
  	isdnloop_card *card = (isdnloop_card *) data;
  	isdnloop_atimeout(card, 1);
  }
  
  /*
   * Install a watchdog for a user, not responding.
   *
   * Parameter:
   *   card = pointer to card struct.
   *   ch   = channel to watch for.
   */
  static void
  isdnloop_start_ctimer(isdnloop_card * card, int ch)
  {
  	unsigned long flags;
  
  	save_flags(flags);
  	cli();
  	init_timer(&card->c_timer[ch]);
  	card->c_timer[ch].expires = jiffies + ISDNLOOP_TIMER_ALERTWAIT;
  	if (ch)
  		card->c_timer[ch].function = isdnloop_atimeout1;
  	else
  		card->c_timer[ch].function = isdnloop_atimeout0;
  	card->c_timer[ch].data = (unsigned long) card;
  	add_timer(&card->c_timer[ch]);
  	restore_flags(flags);
  }
  
  /*
   * Kill a pending channel watchdog.
   *
   * Parameter:
   *   card = pointer to card struct.
   *   ch   = channel (0-based).
   */
  static void
  isdnloop_kill_ctimer(isdnloop_card * card, int ch)
  {
  	unsigned long flags;
  
  	save_flags(flags);
  	cli();
  	del_timer(&card->c_timer[ch]);
  	restore_flags(flags);
  }
  
  static u_char si2bit[] =
  {0, 1, 0, 0, 0, 2, 0, 4, 0, 0};
  static u_char bit2si[] =
  {1, 5, 7};
  
  /*
   * Try finding a listener for an outgoing call.
   *
   * Parameter:
   *   card = pointer to calling card.
   *   p    = pointer to ICN-type setup-string.
   *   lch  = channel of calling card.
   *   cmd  = pointer to struct to be filled when parsing setup.
   * Return:
   *   0 = found match, alerting should happen.
   *   1 = found matching number but it is busy.
   *   2 = no matching listener.
   *   3 = found matching number but SI does not match.
   */
  static int
  isdnloop_try_call(isdnloop_card * card, char *p, int lch, isdn_ctrl * cmd)
  {
  	isdnloop_card *cc = cards;
  	unsigned long flags;
  	int ch;
  	int num_match;
  	int i;
  	char *e;
  	char nbuf[32];
  
  	isdnloop_parse_setup(p, cmd);
  	while (cc) {
  		for (ch = 0; ch < 2; ch++) {
  			/* Exclude ourself */
  			if ((cc == card) && (ch == lch))
  				continue;
  			num_match = 0;
  			switch (cc->ptype) {
  				case ISDN_PTYPE_EURO:
  					for (i = 0; i < 3; i++)
  						if (!(strcmp(cc->s0num[i], cmd->parm.setup.phone)))
  							num_match = 1;
  					break;
  				case ISDN_PTYPE_1TR6:
  					e = cc->eazlist[ch];
  					while (*e) {
  						sprintf(nbuf, "%s%c", cc->s0num[0], *e);
  						if (!(strcmp(nbuf, cmd->parm.setup.phone)))
  							num_match = 1;
  						e++;
  					}
  			}
  			if (num_match) {
  				save_flags(flags);
  				cli();
  				/* channel idle? */
  				if (!(cc->rcard[ch])) {
  					/* Check SI */
  					if (!(si2bit[cmd->parm.setup.si1] & cc->sil[ch])) {
  						restore_flags(flags);
  						return 3;
  					}
  					/* ch is idle, si and number matches */
  					cc->rcard[ch] = card;
  					cc->rch[ch] = lch;
  					card->rcard[lch] = cc;
  					card->rch[lch] = ch;
  					restore_flags(flags);
  					return 0;
  				} else {
  					restore_flags(flags);
  					/* num matches, but busy */
  					if (ch == 1)
  						return 1;
  				}
  			}
  		}
  		cc = cc->next;
  	}
  	return 2;
  }
  
  /*
   * Depending on D-channel protocol and caller/called, modify
   * phone number.
   *
   * Parameter:
   *   card   = pointer to card struct.
   *   phone  = pointer phone number.
   *   caller = flag: 1 = caller, 0 = called.
   * Return:
   *   pointer to new phone number.
   */
  static char *
  isdnloop_vstphone(isdnloop_card * card, char *phone, int caller)
  {
  	int i;
  	static char nphone[30];
  
  	switch (card->ptype) {
  		case ISDN_PTYPE_EURO:
  			if (caller) {
  				for (i = 0; i < 2; i++)
  					if (!(strcmp(card->s0num[i], phone)))
  						return (phone);
  				return (card->s0num[0]);
  			}
  			return (phone);
  			break;
  		case ISDN_PTYPE_1TR6:
  			if (caller) {
  				sprintf(nphone, "%s%c", card->s0num[0], phone[0]);
  				return (nphone);
  			} else
  				return (&phone[strlen(phone) - 1]);
  			break;
  	}
  	return ("\0");
  }
  
  /*
   * Parse an ICN-type command string sent to the 'card'.
   * Perform misc. actions depending on the command.
   *
   * Parameter:
   *   card = pointer to card struct.
   */
  static void
  isdnloop_parse_cmd(isdnloop_card * card)
  {
  	char *p = card->omsg;
  	isdn_ctrl cmd;
  	char buf[60];
  	isdnloop_stat *s = isdnloop_cmd_table;
  	int action = -1;
  	int i;
  	int ch;
  
  	if ((card->omsg[0] != '0') && (card->omsg[2] != ';')) {
  		isdnloop_fake_err(card);
  		return;
  	}
  	ch = card->omsg[1] - '0';
  	if ((ch < 0) || (ch > 2)) {
  		isdnloop_fake_err(card);
  		return;
  	}
  	p += 3;
  	while (s->statstr) {
  		if (!strncmp(p, s->statstr, strlen(s->statstr))) {
  			action = s->action;
  			if (s->command && (ch != 0)) {
  				isdnloop_fake_err(card);
  				return;
  			}
  			break;
  		}
  		s++;
  	}
  	if (action == -1)
  		return;
  	switch (action) {
  		case 1:
  			/* 0x;BCON_R */
  			if (card->rcard[ch - 1]) {
  				isdnloop_fake(card->rcard[ch - 1], "BCON_I",
  					      card->rch[ch - 1] + 1);
  				isdnloop_fake(card, "BCON_C", ch);
  			}
  			break;
  		case 17:
  			/* 0x;BCON_I */
  			if (card->rcard[ch - 1]) {
  				isdnloop_fake(card->rcard[ch - 1], "BCON_C",
  					      card->rch[ch - 1] + 1);
  			}
  			break;
  		case 2:
  			/* 0x;BDIS_R */
  			isdnloop_fake(card, "BDIS_C", ch);
  			if (card->rcard[ch - 1]) {
  				isdnloop_fake(card->rcard[ch - 1], "BDIS_I",
  					      card->rch[ch - 1] + 1);
  			}
  			break;
  		case 16:
  			/* 0x;DCON_R */
  			isdnloop_kill_ctimer(card, ch - 1);
  			if (card->rcard[ch - 1]) {
  				isdnloop_kill_ctimer(card->rcard[ch - 1], card->rch[ch - 1]);
  				isdnloop_fake(card->rcard[ch - 1], "DCON_C",
  					      card->rch[ch - 1] + 1);
  				isdnloop_fake(card, "DCON_C", ch);
  			}
  			break;
  		case 3:
  			/* 0x;DDIS_R */
  			isdnloop_kill_ctimer(card, ch - 1);
  			if (card->rcard[ch - 1]) {
  				isdnloop_kill_ctimer(card->rcard[ch - 1], card->rch[ch - 1]);
  				isdnloop_fake(card->rcard[ch - 1], "DDIS_I",
  					      card->rch[ch - 1] + 1);
  				card->rcard[ch - 1] = NULL;
  			}
  			isdnloop_fake(card, "DDIS_C", ch);
  			break;
  		case 4:
  			/* 0x;DSCA_Rdd,yy,zz,oo */
  			if (card->ptype != ISDN_PTYPE_1TR6) {
  				isdnloop_fake_err(card);
  				return;
  			}
  			/* Fall through */
  		case 5:
  			/* 0x;DCAL_Rdd,yy,zz,oo */
  			p += 6;
  			switch (isdnloop_try_call(card, p, ch - 1, &cmd)) {
  				case 0:
  					/* Alerting */
  					sprintf(buf, "D%s_I%s,%02d,%02d,%s",
  					   (action == 4) ? "SCA" : "CAL",
  						isdnloop_vstphone(card, cmd.parm.setup.eazmsn, 1),
  						cmd.parm.setup.si1,
  						cmd.parm.setup.si2,
  					isdnloop_vstphone(card->rcard[ch],
  					       cmd.parm.setup.phone, 0));
  					isdnloop_fake(card->rcard[ch - 1], buf, card->rch[ch - 1] + 1);
  					/* Fall through */
  				case 3:
  					/* si1 does not match, don't alert but start timer */
  					isdnloop_start_ctimer(card, ch - 1);
  					break;
  				case 1:
  					/* Remote busy */
  					isdnloop_fake(card, "DDIS_I", ch);
  					sprintf(buf, "CAU%s", isdnloop_unicause(card, 1, 1));
  					isdnloop_fake(card, buf, ch);
  					break;
  				case 2:
  					/* No such user */
  					isdnloop_fake(card, "DDIS_I", ch);
  					sprintf(buf, "CAU%s", isdnloop_unicause(card, 1, 2));
  					isdnloop_fake(card, buf, ch);
  					break;
  			}
  			break;
  		case 6:
  			/* 0x;EAZC */
  			card->eazlist[ch - 1][0] = '\0';
  			break;
  		case 7:
  			/* 0x;EAZ */
  			p += 3;
  			strcpy(card->eazlist[ch - 1], p);
  			break;
  		case 8:
  			/* 0x;SEEAZ */
  			sprintf(buf, "EAZ-LIST: %s", card->eazlist[ch - 1]);
  			isdnloop_fake(card, buf, ch + 1);
  			break;
  		case 9:
  			/* 0x;MSN */
  			break;
  		case 10:
  			/* 0x;MSNALL */
  			break;
  		case 11:
  			/* 0x;SETSIL */
  			p += 6;
  			i = 0;
  			while (strchr("0157", *p)) {
  				if (i)
  					card->sil[ch - 1] |= si2bit[*p - '0'];
  				i = (*p++ == '0');
  			}
  			if (*p)
  				isdnloop_fake_err(card);
  			break;
  		case 12:
  			/* 0x;SEESIL */
  			sprintf(buf, "SIN-LIST: ");
  			p = buf + 10;
  			for (i = 0; i < 3; i++)
  				if (card->sil[ch - 1] & (1 << i))
  					p += sprintf(p, "%02d", bit2si[i]);
  			isdnloop_fake(card, buf, ch + 1);
  			break;
  		case 13:
  			/* 0x;SILC */
  			card->sil[ch - 1] = 0;
  			break;
  		case 14:
  			/* 00;FV2ON */
  			break;
  		case 15:
  			/* 00;FV2OFF */
  			break;
  	}
  }
  
  /*
   * Put command-strings into the of the 'card'. In reality, execute them
   * right in place by calling isdnloop_parse_cmd(). Also copy every
   * command to the read message ringbuffer, preceeding it with a '>'.
   * These mesagges can be read at /dev/isdnctrl.
   *
   * Parameter:
   *   buf  = pointer to command buffer.
   *   len  = length of buffer data.
   *   user = flag: 1 = called form userlevel, 0 called from kernel.
   *   card = pointer to card struct.
   * Return:
   *   number of bytes transferred (currently always equals len).
   */
  static int
  isdnloop_writecmd(const u_char * buf, int len, int user, isdnloop_card * card)
  {
  	int xcount = 0;
  	int ocount = 1;
  	isdn_ctrl cmd;
  
  	while (len) {
  		int count = len;
  		u_char *p;
  		u_char msg[0x100];
  
  		if (count > 255)
  			count = 255;
  		if (user)
  			copy_from_user(msg, buf, count);
  		else
  			memcpy(msg, buf, count);
  		isdnloop_putmsg(card, '>');
  		for (p = msg; count > 0; count--, p++) {
  			len--;
  			xcount++;
  			isdnloop_putmsg(card, *p);
  			card->omsg[card->optr] = *p;
  			if (*p == '\n') {
  				card->omsg[card->optr] = '\0';
  				card->optr = 0;
  				isdnloop_parse_cmd(card);
  				if (len) {
  					isdnloop_putmsg(card, '>');
  					ocount++;
  				}
  			} else {
  				if (card->optr < 59)
  					card->optr++;
  			}
  			ocount++;
  		}
  	}
  	cmd.command = ISDN_STAT_STAVAIL;
  	cmd.driver = card->myid;
  	cmd.arg = ocount;
  	card->interface.statcallb(&cmd);
  	return xcount;
  }
  
  /*
   * Delete card's pending timers, send STOP to linklevel
   */
  static void
  isdnloop_stopcard(isdnloop_card * card)
  {
  	unsigned long flags;
  	isdn_ctrl cmd;
  
  	save_flags(flags);
  	cli();
  	if (card->flags & ISDNLOOP_FLAGS_RUNNING) {
  		card->flags &= ~ISDNLOOP_FLAGS_RUNNING;
  		del_timer(&card->st_timer);
  		del_timer(&card->rb_timer);
  		del_timer(&card->c_timer[0]);
  		del_timer(&card->c_timer[1]);
  		cmd.command = ISDN_STAT_STOP;
  		cmd.driver = card->myid;
  		card->interface.statcallb(&cmd);
  	}
  	restore_flags(flags);
  }
  
  /*
   * Stop all cards before unload.
   */
  static void
  isdnloop_stopallcards(void)
  {
  	isdnloop_card *p = cards;
  
  	while (p) {
  		isdnloop_stopcard(p);
  		p = p->next;
  	}
  }
  
  /*
   * Start a 'card'. Simulate card's boot message and set the phone
   * number(s) of the virtual 'S0-Interface'. Install D-channel
   * poll timer.
   *
   * Parameter:
   *   card  = pointer to card struct.
   *   sdefp = pointer to struct holding ioctl parameters.
   * Return:
   *   0 on success, -E??? otherwise.
   */
  static int
  isdnloop_start(isdnloop_card * card, isdnloop_sdef * sdefp)
  {
  	unsigned long flags;
  	isdnloop_sdef sdef;
  	int i;
  
  	if (card->flags & ISDNLOOP_FLAGS_RUNNING)
  		return -EBUSY;
  	copy_from_user((char *) &sdef, (char *) sdefp, sizeof(sdef));
  	save_flags(flags);
  	cli();
  	switch (sdef.ptype) {
  		case ISDN_PTYPE_EURO:
  			if (isdnloop_fake(card, "DRV1.23EC-Q.931-CAPI-CNS-BASIS-20.02.96",
  					  -1)) {
  				restore_flags(flags);
  				return -ENOMEM;
  			}
  			card->sil[0] = card->sil[1] = 4;
  			if (isdnloop_fake(card, "TEI OK", 0)) {
  				restore_flags(flags);
  				return -ENOMEM;
  			}
  			for (i = 0; i < 3; i++)
  				strcpy(card->s0num[i], sdef.num[i]);
  			break;
  		case ISDN_PTYPE_1TR6:
  			if (isdnloop_fake(card, "DRV1.04TC-1TR6-CAPI-CNS-BASIS-29.11.95",
  					  -1)) {
  				restore_flags(flags);
  				return -ENOMEM;
  			}
  			card->sil[0] = card->sil[1] = 4;
  			if (isdnloop_fake(card, "TEI OK", 0)) {
  				restore_flags(flags);
  				return -ENOMEM;
  			}
  			strcpy(card->s0num[0], sdef.num[0]);
  			card->s0num[1][0] = '\0';
  			card->s0num[2][0] = '\0';
  			break;
  		default:
  			restore_flags(flags);
  			printk(KERN_WARNING "isdnloop: Illegal D-channel protocol %d\n",
  			       sdef.ptype);
  			return -EINVAL;
  	}
  	init_timer(&card->st_timer);
  	card->st_timer.expires = jiffies + ISDNLOOP_TIMER_DCREAD;
  	card->st_timer.function = isdnloop_polldchan;
  	card->st_timer.data = (unsigned long) card;
  	add_timer(&card->st_timer);
  	card->flags |= ISDNLOOP_FLAGS_RUNNING;
  	restore_flags(flags);
  	return 0;
  }
  
  /*
   * Main handler for commands sent by linklevel.
   */
  static int
  isdnloop_command(isdn_ctrl * c, isdnloop_card * card)
  {
  	ulong a;
  	int i;
  	char cbuf[60];
  	isdn_ctrl cmd;
  	isdnloop_cdef cdef;
  
  	switch (c->command) {
  		case ISDN_CMD_IOCTL:
  			memcpy(&a, c->parm.num, sizeof(ulong));
  			switch (c->arg) {
  				case ISDNLOOP_IOCTL_DEBUGVAR:
  					return (ulong) card;
  				case ISDNLOOP_IOCTL_STARTUP:
  					if ((i = verify_area(VERIFY_READ, (void *) a, sizeof(isdnloop_sdef))))
  						return i;
  					return (isdnloop_start(card, (isdnloop_sdef *) a));
  					break;
  				case ISDNLOOP_IOCTL_ADDCARD:
  					if ((i = verify_area(VERIFY_READ, (void *) a, sizeof(isdnloop_cdef))))
  						return i;
  					copy_from_user((char *) &cdef, (char *) a, sizeof(cdef));
  					return (isdnloop_addcard(cdef.id1));
  					break;
  				case ISDNLOOP_IOCTL_LEASEDCFG:
  					if (a) {
  						if (!card->leased) {
  							card->leased = 1;
  							while (card->ptype == ISDN_PTYPE_UNKNOWN) {
  								schedule_timeout(10);
  							}
  							schedule_timeout(10);
  							sprintf(cbuf, "00;FV2ON\n01;EAZ1\n02;EAZ2\n");
  							i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  							printk(KERN_INFO
  							       "isdnloop: (%s) Leased-line mode enabled\n",
  							       CID);
  							cmd.command = ISDN_STAT_RUN;
  							cmd.driver = card->myid;
  							cmd.arg = 0;
  							card->interface.statcallb(&cmd);
  						}
  					} else {
  						if (card->leased) {
  							card->leased = 0;
  							sprintf(cbuf, "00;FV2OFF\n");
  							i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  							printk(KERN_INFO
  							       "isdnloop: (%s) Leased-line mode disabled\n",
  							       CID);
  							cmd.command = ISDN_STAT_RUN;
  							cmd.driver = card->myid;
  							cmd.arg = 0;
  							card->interface.statcallb(&cmd);
  						}
  					}
  					return 0;
  				default:
  					return -EINVAL;
  			}
  			break;
  		case ISDN_CMD_DIAL:
  			if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  				return -ENODEV;
  			if (card->leased)
  				break;
  			if ((c->arg & 255) < ISDNLOOP_BCH) {
  				char *p;
  				char dial[50];
  				char dcode[4];
  
  				a = c->arg;
  				p = c->parm.setup.phone;
  				if (*p == 's' || *p == 'S') {
  					/* Dial for SPV */
  					p++;
  					strcpy(dcode, "SCA");
  				} else
  					/* Normal Dial */
  					strcpy(dcode, "CAL");
  				strcpy(dial, p);
  				sprintf(cbuf, "%02d;D%s_R%s,%02d,%02d,%s\n", (int) (a + 1),
  					dcode, dial, c->parm.setup.si1,
  				c->parm.setup.si2, c->parm.setup.eazmsn);
  				i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  			}
  			break;
  		case ISDN_CMD_ACCEPTD:
  			if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  				return -ENODEV;
  			if (c->arg < ISDNLOOP_BCH) {
  				a = c->arg + 1;
  				cbuf[0] = 0;
  				switch (card->l2_proto[a - 1]) {
  					case ISDN_PROTO_L2_X75I:
  						sprintf(cbuf, "%02d;BX75\n", (int) a);
  						break;
  #ifdef CONFIG_ISDN_X25
  					case ISDN_PROTO_L2_X25DTE:
  						sprintf(cbuf, "%02d;BX2T\n", (int) a);
  						break;
  					case ISDN_PROTO_L2_X25DCE:
  						sprintf(cbuf, "%02d;BX2C\n", (int) a);
  						break;
  #endif
  					case ISDN_PROTO_L2_HDLC:
  						sprintf(cbuf, "%02d;BTRA\n", (int) a);
  						break;
  				}
  				if (strlen(cbuf))
  					i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  				sprintf(cbuf, "%02d;DCON_R\n", (int) a);
  				i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  			}
  			break;
  		case ISDN_CMD_ACCEPTB:
  			if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  				return -ENODEV;
  			if (c->arg < ISDNLOOP_BCH) {
  				a = c->arg + 1;
  				switch (card->l2_proto[a - 1]) {
  					case ISDN_PROTO_L2_X75I:
  						sprintf(cbuf, "%02d;BCON_R,BX75\n", (int) a);
  						break;
  #ifdef CONFIG_ISDN_X25
  					case ISDN_PROTO_L2_X25DTE:
  						sprintf(cbuf, "%02d;BCON_R,BX2T\n", (int) a);
  						break;
  					case ISDN_PROTO_L2_X25DCE:
  						sprintf(cbuf, "%02d;BCON_R,BX2C\n", (int) a);
  						break;
  #endif
  					case ISDN_PROTO_L2_HDLC:
  						sprintf(cbuf, "%02d;BCON_R,BTRA\n", (int) a);
  						break;
  					default:
  						sprintf(cbuf, "%02d;BCON_R\n", (int) a);
  				}
  				printk(KERN_DEBUG "isdnloop writecmd '%s'\n", cbuf);
  				i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  				break;
  		case ISDN_CMD_HANGUP:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				if (c->arg < ISDNLOOP_BCH) {
  					a = c->arg + 1;
  					sprintf(cbuf, "%02d;BDIS_R\n%02d;DDIS_R\n", (int) a, (int) a);
  					i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  				}
  				break;
  		case ISDN_CMD_SETEAZ:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				if (card->leased)
  					break;
  				if (c->arg < ISDNLOOP_BCH) {
  					a = c->arg + 1;
  					if (card->ptype == ISDN_PTYPE_EURO) {
  						sprintf(cbuf, "%02d;MS%s%s\n", (int) a,
  							c->parm.num[0] ? "N" : "ALL", c->parm.num);
  					} else
  						sprintf(cbuf, "%02d;EAZ%s\n", (int) a,
  							c->parm.num[0] ? c->parm.num : (u_char *) "0123456789");
  					i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  				}
  				break;
  		case ISDN_CMD_CLREAZ:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				if (card->leased)
  					break;
  				if (c->arg < ISDNLOOP_BCH) {
  					a = c->arg + 1;
  					if (card->ptype == ISDN_PTYPE_EURO)
  						sprintf(cbuf, "%02d;MSNC\n", (int) a);
  					else
  						sprintf(cbuf, "%02d;EAZC\n", (int) a);
  					i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  				}
  				break;
  		case ISDN_CMD_SETL2:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				if ((c->arg & 255) < ISDNLOOP_BCH) {
  					a = c->arg;
  					switch (a >> 8) {
  						case ISDN_PROTO_L2_X75I:
  							sprintf(cbuf, "%02d;BX75\n", (int) (a & 255) + 1);
  							break;
  #ifdef CONFIG_ISDN_X25
  						case ISDN_PROTO_L2_X25DTE:
  							sprintf(cbuf, "%02d;BX2T\n", (int) (a & 255) + 1);
  							break;
  						case ISDN_PROTO_L2_X25DCE:
  							sprintf(cbuf, "%02d;BX2C\n", (int) (a & 255) + 1);
  							break;
  #endif
  						case ISDN_PROTO_L2_HDLC:
  							sprintf(cbuf, "%02d;BTRA\n", (int) (a & 255) + 1);
  							break;
  						default:
  							return -EINVAL;
  					}
  					i = isdnloop_writecmd(cbuf, strlen(cbuf), 0, card);
  					card->l2_proto[a & 255] = (a >> 8);
  				}
  				break;
  		case ISDN_CMD_GETL2:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				if ((c->arg & 255) < ISDNLOOP_BCH)
  					return card->l2_proto[c->arg & 255];
  				else
  					return -ENODEV;
  		case ISDN_CMD_SETL3:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				return 0;
  		case ISDN_CMD_GETL3:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				if ((c->arg & 255) < ISDNLOOP_BCH)
  					return ISDN_PROTO_L3_TRANS;
  				else
  					return -ENODEV;
  		case ISDN_CMD_GETEAZ:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				break;
  		case ISDN_CMD_SETSIL:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				break;
  		case ISDN_CMD_GETSIL:
  				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  					return -ENODEV;
  				break;
  		case ISDN_CMD_LOCK:
  				MOD_INC_USE_COUNT;
  				break;
  		case ISDN_CMD_UNLOCK:
  				MOD_DEC_USE_COUNT;
  				break;
  		default:
  				return -EINVAL;
  			}
  	}
  	return 0;
  }
  
  /*
   * Find card with given driverId
   */
  static inline isdnloop_card *
  isdnloop_findcard(int driverid)
  {
  	isdnloop_card *p = cards;
  
  	while (p) {
  		if (p->myid == driverid)
  			return p;
  		p = p->next;
  	}
  	return (isdnloop_card *) 0;
  }
  
  /*
   * Wrapper functions for interface to linklevel
   */
  static int
  if_command(isdn_ctrl * c)
  {
  	isdnloop_card *card = isdnloop_findcard(c->driver);
  
  	if (card)
  		return (isdnloop_command(c, card));
  	printk(KERN_ERR
  	       "isdnloop: if_command called with invalid driverId!\n");
  	return -ENODEV;
  }
  
  static int
  if_writecmd(const u_char * buf, int len, int user, int id, int channel)
  {
  	isdnloop_card *card = isdnloop_findcard(id);
  
  	if (card) {
  		if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  			return -ENODEV;
  		return (isdnloop_writecmd(buf, len, user, card));
  	}
  	printk(KERN_ERR
  	       "isdnloop: if_writecmd called with invalid driverId!\n");
  	return -ENODEV;
  }
  
  static int
  if_readstatus(u_char * buf, int len, int user, int id, int channel)
  {
  	isdnloop_card *card = isdnloop_findcard(id);
  
  	if (card) {
  		if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  			return -ENODEV;
  		return (isdnloop_readstatus(buf, len, user, card));
  	}
  	printk(KERN_ERR
  	       "isdnloop: if_readstatus called with invalid driverId!\n");
  	return -ENODEV;
  }
  
  static int
  if_sendbuf(int id, int channel, int ack, struct sk_buff *skb)
  {
  	isdnloop_card *card = isdnloop_findcard(id);
  
  	if (card) {
  		if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
  			return -ENODEV;
  		/* ack request stored in skb scratch area */
  		*(skb->head) = ack;
  		return (isdnloop_sendbuf(channel, skb, card));
  	}
  	printk(KERN_ERR
  	       "isdnloop: if_sendbuf called with invalid driverId!\n");
  	return -ENODEV;
  }
  
  /*
   * Allocate a new card-struct, initialize it
   * link it into cards-list and register it at linklevel.
   */
  static isdnloop_card *
  isdnloop_initcard(char *id)
  {
  	isdnloop_card *card;
  	int i;
  
  	if (!(card = (isdnloop_card *) kmalloc(sizeof(isdnloop_card), GFP_KERNEL))) {
  		printk(KERN_WARNING
  		 "isdnloop: (%s) Could not allocate card-struct.\n", id);
  		return (isdnloop_card *) 0;
  	}
  	memset((char *) card, 0, sizeof(isdnloop_card));
  	card->interface.channels = ISDNLOOP_BCH;
  	card->interface.hl_hdrlen  = 1; /* scratch area for storing ack flag*/ 
  	card->interface.maxbufsize = 4000;
  	card->interface.command = if_command;
  	card->interface.writebuf_skb = if_sendbuf;
  	card->interface.writecmd = if_writecmd;
  	card->interface.readstat = if_readstatus;
  	card->interface.features = ISDN_FEATURE_L2_X75I |
  #ifdef CONFIG_ISDN_X25
  	    ISDN_FEATURE_L2_X25DTE |
  	    ISDN_FEATURE_L2_X25DCE |
  #endif
  	    ISDN_FEATURE_L2_HDLC |
  	    ISDN_FEATURE_L3_TRANS |
  	    ISDN_FEATURE_P_UNKNOWN;
  	card->ptype = ISDN_PTYPE_UNKNOWN;
  	strncpy(card->interface.id, id, sizeof(card->interface.id) - 1);
  	card->msg_buf_write = card->msg_buf;
  	card->msg_buf_read = card->msg_buf;
  	card->msg_buf_end = &card->msg_buf[sizeof(card->msg_buf) - 1];
  	for (i = 0; i < ISDNLOOP_BCH; i++) {
  		card->l2_proto[i] = ISDN_PROTO_L2_X75I;
  		skb_queue_head_init(&card->bqueue[i]);
  	}
  	skb_queue_head_init(&card->dqueue);
  	card->next = cards;
  	cards = card;
  	if (!register_isdn(&card->interface)) {
  		cards = cards->next;
  		printk(KERN_WARNING
  		       "isdnloop: Unable to register %s\n", id);
  		kfree(card);
  		return (isdnloop_card *) 0;
  	}
  	card->myid = card->interface.channels;
  	return card;
  }
  
  static int
  isdnloop_addcard(char *id1)
  {
  	isdnloop_card *card;
  
  	if (!(card = isdnloop_initcard(id1))) {
  		return -EIO;
  	}
  	printk(KERN_INFO
  	       "isdnloop: (%s) virtual card added\n",
  	       card->interface.id);
  	return 0;
  }
  
  static int __init
  isdnloop_init(void)
  {
  	char *p;
  	char rev[10];
  
  	/* No symbols to export, hide all symbols */
  	EXPORT_NO_SYMBOLS;
  
  	if ((p = strchr(revision, ':'))) {
  		strcpy(rev, p + 1);
  		p = strchr(rev, '$');
  		*p = 0;
  	} else
  		strcpy(rev, " ??? ");
  	printk(KERN_NOTICE "isdnloop-ISDN-driver Rev%s\n", rev);
  
  	if (isdnloop_id)
  		return (isdnloop_addcard(isdnloop_id));
  
  	return 0;
  }
  
  static void __exit
  isdnloop_exit(void)
  {
  	isdn_ctrl cmd;
  	isdnloop_card *card = cards;
  	isdnloop_card *last;
  	int i;
  
  	isdnloop_stopallcards();
  	while (card) {
  		cmd.command = ISDN_STAT_UNLOAD;
  		cmd.driver = card->myid;
  		card->interface.statcallb(&cmd);
  		for (i = 0; i < ISDNLOOP_BCH; i++)
  			isdnloop_free_queue(card, i);
  		card = card->next;
  	}
  	card = cards;
  	while (card) {
  		last = card;
  		skb_queue_purge(&card->dqueue);
  		card = card->next;
  		kfree(last);
  	}
  	printk(KERN_NOTICE "isdnloop-ISDN-driver unloaded\n");
  }
  
  module_init(isdnloop_init);
  module_exit(isdnloop_exit);
  