diff --git a/drivers/isdn/isdnloop/Makefile b/drivers/isdn/isdnloop/Makefile
new file mode 100644
index 0000000..317cd3c
--- /dev/null
+++ b/drivers/isdn/isdnloop/Makefile
@@ -0,0 +1,5 @@
+# Makefile for the isdnloop ISDN device driver
+
+# Each configuration option enables a list of files.
+
+obj-$(CONFIG_ISDN_DRV_LOOP)	+= isdnloop.o
diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c
new file mode 100644
index 0000000..14e1f8f
--- /dev/null
+++ b/drivers/isdn/isdnloop/isdnloop.c
@@ -0,0 +1,1554 @@
+/* $Id: isdnloop.c,v 1.11.6.7 2001/11/11 19:54:31 kai 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/interrupt.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include "isdnloop.h"
+
+static char *revision = "$Revision: 1.11.6.7 $";
+static char *isdnloop_id = "loop0";
+
+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_BSENT;
+			cmd.parm.length = len;
+			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 = strchr(t, ',');
+
+	*s++ = '\0';
+	strlcpy(cmd->parm.setup.phone, t, sizeof(cmd->parm.setup.phone));
+	s = strchr(t = s, ',');
+	*s++ = '\0';
+	if (!strlen(t))
+		cmd->parm.setup.si1 = 0;
+	else
+		cmd->parm.setup.si1 = simple_strtoul(t, NULL, 10);
+	s = strchr(t = s, ',');
+	*s++ = '\0';
+	if (!strlen(t))
+		cmd->parm.setup.si2 = 0;
+	else
+		cmd->parm.setup.si2 =
+		    simple_strtoul(t, NULL, 10);
+	strlcpy(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 */
+	{"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 */
+			strlcpy(cmd.parm.num, status + 3, sizeof(cmd.parm.num));
+			break;
+		case 6:
+			/* AOC */
+			snprintf(cmd.parm.num, sizeof(cmd.parm.num), "%d",
+			     (int) simple_strtoul(status + 7, NULL, 16));
+			break;
+		case 7:
+			/* CAU */
+			status += 3;
+			if (strlen(status) == 4)
+				snprintf(cmd.parm.num, sizeof(cmd.parm.num), "%s%c%c",
+				     status + 2, *status, *(status + 1));
+			else
+				strlcpy(cmd.parm.num, status + 1, sizeof(cmd.parm.num));
+			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 = dev_alloc_skb(skb->len);
+		if (nskb) {
+			memcpy(skb_put(nskb, len), skb->data, len);
+			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 __user *buf, int len, isdnloop_card * card)
+{
+	int count;
+	u_char __user *p;
+
+	for (p = buf, count = 0; count < len; p++, count++) {
+		if (card->msg_buf_read == card->msg_buf_write)
+			return count;
+		put_user(*card->msg_buf_read++, p);
+		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];
+
+	if (!card) {
+		printk("BUG!!!\n");
+		return "";
+	}
+	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 "";
+}
+
+/*
+ * 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 - 1],
+					       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) {
+			if (copy_from_user(msg, buf, count))
+				return -EFAULT;
+		} 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;
+	if (copy_from_user((char *) &sdef, (char *) sdefp, sizeof(sdef)))
+		return -EFAULT;
+	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 (!access_ok(VERIFY_READ, (void *) a, sizeof(isdnloop_sdef)))
+						return -EFAULT;
+					return (isdnloop_start(card, (isdnloop_sdef *) a));
+					break;
+				case ISDNLOOP_IOCTL_ADDCARD:
+					if (copy_from_user((char *)&cdef,
+							   (char *)a,
+							   sizeof(cdef)))
+						return -EFAULT;
+					return (isdnloop_addcard(cdef.id1));
+					break;
+				case ISDNLOOP_IOCTL_LEASEDCFG:
+					if (a) {
+						if (!card->leased) {
+							card->leased = 1;
+							while (card->ptype == ISDN_PTYPE_UNKNOWN) {
+								set_current_state(TASK_INTERRUPTIBLE);
+								schedule_timeout(10);
+							}
+							set_current_state(TASK_INTERRUPTIBLE);
+							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;
+						case ISDN_PROTO_L2_TRANS:
+							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_SETL3:
+				if (!card->flags & ISDNLOOP_FLAGS_RUNNING)
+					return -ENODEV;
+				return 0;
+		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 __user *buf, int len, 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, 1, card));
+	}
+	printk(KERN_ERR
+	       "isdnloop: if_writecmd called with invalid driverId!\n");
+	return -ENODEV;
+}
+
+static int
+if_readstatus(u_char __user *buf, int len, 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, 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.owner = THIS_MODULE;
+	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;
+	strlcpy(card->interface.id, id, sizeof(card->interface.id));
+	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];
+
+	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);
diff --git a/drivers/isdn/isdnloop/isdnloop.h b/drivers/isdn/isdnloop/isdnloop.h
new file mode 100644
index 0000000..8fb7bc1
--- /dev/null
+++ b/drivers/isdn/isdnloop/isdnloop.h
@@ -0,0 +1,112 @@
+/* $Id: isdnloop.h,v 1.5.6.3 2001/09/23 22:24:56 kai Exp $
+ *
+ * Loopback lowlevel module for testing of linklevel.
+ *
+ * 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.
+ *
+ */
+
+#ifndef isdnloop_h
+#define isdnloop_h
+
+#define ISDNLOOP_IOCTL_DEBUGVAR  0
+#define ISDNLOOP_IOCTL_ADDCARD   1
+#define ISDNLOOP_IOCTL_LEASEDCFG 2
+#define ISDNLOOP_IOCTL_STARTUP   3
+
+/* Struct for adding new cards */
+typedef struct isdnloop_cdef {
+	char id1[10];
+} isdnloop_cdef;
+
+/* Struct for configuring cards */
+typedef struct isdnloop_sdef {
+	int ptype;
+	char num[3][20];
+} isdnloop_sdef;
+
+#if defined(__KERNEL__) || defined(__DEBUGVAR__)
+
+#ifdef __KERNEL__
+/* Kernel includes */
+
+#include <linux/version.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/major.h>
+#include <asm/io.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/ioport.h>
+#include <linux/timer.h>
+#include <linux/wait.h>
+#include <linux/isdnif.h>
+
+#endif                          /* __KERNEL__ */
+
+#define ISDNLOOP_FLAGS_B1ACTIVE 1	/* B-Channel-1 is open           */
+#define ISDNLOOP_FLAGS_B2ACTIVE 2	/* B-Channel-2 is open           */
+#define ISDNLOOP_FLAGS_RUNNING  4	/* Cards driver activated        */
+#define ISDNLOOP_FLAGS_RBTIMER  8	/* scheduling of B-Channel-poll  */
+#define ISDNLOOP_TIMER_BCREAD 1 /* B-Channel poll-cycle          */
+#define ISDNLOOP_TIMER_DCREAD (HZ/2)	/* D-Channel poll-cycle          */
+#define ISDNLOOP_TIMER_ALERTWAIT (10*HZ)	/* Alert timeout                 */
+#define ISDNLOOP_MAX_SQUEUE 65536	/* Max. outstanding send-data    */
+#define ISDNLOOP_BCH 2          /* channels per card             */
+
+/*
+ * Per card driver data
+ */
+typedef struct isdnloop_card {
+	struct isdnloop_card *next;	/* Pointer to next device struct    */
+	struct isdnloop_card
+	*rcard[ISDNLOOP_BCH];   /* Pointer to 'remote' card         */
+	int rch[ISDNLOOP_BCH];  /* 'remote' channel                 */
+	int myid;               /* Driver-Nr. assigned by linklevel */
+	int leased;             /* Flag: This Adapter is connected  */
+	/*       to a leased line           */
+	int sil[ISDNLOOP_BCH];  /* SI's to listen for               */
+	char eazlist[ISDNLOOP_BCH][11];
+	/* EAZ's to listen for              */
+	char s0num[3][20];      /* 1TR6 base-number or MSN's        */
+	unsigned short flags;   /* Statusflags                      */
+	int ptype;              /* Protocol type (1TR6 or Euro)     */
+	struct timer_list st_timer;	/* Timer for Status-Polls           */
+	struct timer_list rb_timer;	/* Timer for B-Channel-Polls        */
+	struct timer_list
+	 c_timer[ISDNLOOP_BCH]; /* Timer for Alerting               */
+	int l2_proto[ISDNLOOP_BCH];	/* Current layer-2-protocol         */
+	isdn_if interface;      /* Interface to upper layer         */
+	int iptr;               /* Index to imsg-buffer             */
+	char imsg[60];          /* Internal buf for status-parsing  */
+	int optr;               /* Index to omsg-buffer             */
+	char omsg[60];          /* Internal buf for cmd-parsing     */
+	char msg_buf[2048];     /* Buffer for status-messages       */
+	char *msg_buf_write;    /* Writepointer for statusbuffer    */
+	char *msg_buf_read;     /* Readpointer for statusbuffer     */
+	char *msg_buf_end;      /* Pointer to end of statusbuffer   */
+	int sndcount[ISDNLOOP_BCH];	/* Byte-counters for B-Ch.-send     */
+	struct sk_buff_head
+	 bqueue[ISDNLOOP_BCH];  /* B-Channel queues                 */
+	struct sk_buff_head dqueue;	/* D-Channel queue                  */
+} isdnloop_card;
+
+/*
+ * Main driver data
+ */
+#ifdef __KERNEL__
+static isdnloop_card *cards = (isdnloop_card *) 0;
+#endif                          /* __KERNEL__ */
+
+/* Utility-Macros */
+
+#define CID (card->interface.id)
+
+#endif                          /* defined(__KERNEL__) || defined(__DEBUGVAR__) */
+#endif                          /* isdnloop_h */