1/*
2 *	Things to sort out:
3 *
4 *	o	tbusy handling
5 *	o	allow users to set the parameters
6 *	o	sync/async switching ?
7 *
8 *	Note: This does _not_ implement CCITT X.25 asynchronous framing
9 *	recommendations. Its primarily for testing purposes. If you wanted
10 *	to do CCITT then in theory all you need is to nick the HDLC async
11 *	checksum routines from ppp.c
12 *      Changes:
13 *
14 *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/module.h>
20
21#include <linux/uaccess.h>
22#include <linux/bitops.h>
23#include <linux/string.h>
24#include <linux/mm.h>
25#include <linux/interrupt.h>
26#include <linux/in.h>
27#include <linux/tty.h>
28#include <linux/errno.h>
29#include <linux/netdevice.h>
30#include <linux/etherdevice.h>
31#include <linux/skbuff.h>
32#include <linux/if_arp.h>
33#include <linux/lapb.h>
34#include <linux/init.h>
35#include <linux/rtnetlink.h>
36#include <linux/compat.h>
37#include <linux/slab.h>
38#include <net/x25device.h>
39#include "x25_asy.h"
40
41static struct net_device **x25_asy_devs;
42static int x25_asy_maxdev = SL_NRUNIT;
43
44module_param(x25_asy_maxdev, int, 0);
45MODULE_LICENSE("GPL");
46
47static int x25_asy_esc(unsigned char *p, unsigned char *d, int len);
48static void x25_asy_unesc(struct x25_asy *sl, unsigned char c);
49static void x25_asy_setup(struct net_device *dev);
50
51/* Find a free X.25 channel, and link in this `tty' line. */
52static struct x25_asy *x25_asy_alloc(void)
53{
54	struct net_device *dev = NULL;
55	struct x25_asy *sl;
56	int i;
57
58	if (x25_asy_devs == NULL)
59		return NULL;	/* Master array missing ! */
60
61	for (i = 0; i < x25_asy_maxdev; i++) {
62		dev = x25_asy_devs[i];
63
64		/* Not allocated ? */
65		if (dev == NULL)
66			break;
67
68		sl = netdev_priv(dev);
69		/* Not in use ? */
70		if (!test_and_set_bit(SLF_INUSE, &sl->flags))
71			return sl;
72	}
73
74
75	/* Sorry, too many, all slots in use */
76	if (i >= x25_asy_maxdev)
77		return NULL;
78
79	/* If no channels are available, allocate one */
80	if (!dev) {
81		char name[IFNAMSIZ];
82		sprintf(name, "x25asy%d", i);
83
84		dev = alloc_netdev(sizeof(struct x25_asy), name,
85				   NET_NAME_UNKNOWN, x25_asy_setup);
86		if (!dev)
87			return NULL;
88
89		/* Initialize channel control data */
90		sl = netdev_priv(dev);
91		dev->base_addr    = i;
92
93		/* register device so that it can be ifconfig'ed       */
94		if (register_netdev(dev) == 0) {
95			/* (Re-)Set the INUSE bit.   Very Important! */
96			set_bit(SLF_INUSE, &sl->flags);
97			x25_asy_devs[i] = dev;
98			return sl;
99		} else {
100			pr_warn("%s(): register_netdev() failure\n", __func__);
101			free_netdev(dev);
102		}
103	}
104	return NULL;
105}
106
107
108/* Free an X.25 channel. */
109static void x25_asy_free(struct x25_asy *sl)
110{
111	/* Free all X.25 frame buffers. */
112	kfree(sl->rbuff);
113	sl->rbuff = NULL;
114	kfree(sl->xbuff);
115	sl->xbuff = NULL;
116
117	if (!test_and_clear_bit(SLF_INUSE, &sl->flags))
118		netdev_err(sl->dev, "x25_asy_free for already free unit\n");
119}
120
121static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
122{
123	struct x25_asy *sl = netdev_priv(dev);
124	unsigned char *xbuff, *rbuff;
125	int len;
126
127	if (newmtu > 65534)
128		return -EINVAL;
129
130	len = 2 * newmtu;
131	xbuff = kmalloc(len + 4, GFP_ATOMIC);
132	rbuff = kmalloc(len + 4, GFP_ATOMIC);
133
134	if (xbuff == NULL || rbuff == NULL) {
135		kfree(xbuff);
136		kfree(rbuff);
137		return -ENOMEM;
138	}
139
140	spin_lock_bh(&sl->lock);
141	xbuff    = xchg(&sl->xbuff, xbuff);
142	if (sl->xleft)  {
143		if (sl->xleft <= len)  {
144			memcpy(sl->xbuff, sl->xhead, sl->xleft);
145		} else  {
146			sl->xleft = 0;
147			dev->stats.tx_dropped++;
148		}
149	}
150	sl->xhead = sl->xbuff;
151
152	rbuff	 = xchg(&sl->rbuff, rbuff);
153	if (sl->rcount)  {
154		if (sl->rcount <= len) {
155			memcpy(sl->rbuff, rbuff, sl->rcount);
156		} else  {
157			sl->rcount = 0;
158			dev->stats.rx_over_errors++;
159			set_bit(SLF_ERROR, &sl->flags);
160		}
161	}
162
163	dev->mtu    = newmtu;
164	sl->buffsize = len;
165
166	spin_unlock_bh(&sl->lock);
167
168	kfree(xbuff);
169	kfree(rbuff);
170	return 0;
171}
172
173
174/* Set the "sending" flag.  This must be atomic, hence the ASM. */
175
176static inline void x25_asy_lock(struct x25_asy *sl)
177{
178	netif_stop_queue(sl->dev);
179}
180
181
182/* Clear the "sending" flag.  This must be atomic, hence the ASM. */
183
184static inline void x25_asy_unlock(struct x25_asy *sl)
185{
186	netif_wake_queue(sl->dev);
187}
188
189/* Send one completely decapsulated IP datagram to the IP layer. */
190
191static void x25_asy_bump(struct x25_asy *sl)
192{
193	struct net_device *dev = sl->dev;
194	struct sk_buff *skb;
195	int count;
196	int err;
197
198	count = sl->rcount;
199	dev->stats.rx_bytes += count;
200
201	skb = dev_alloc_skb(count+1);
202	if (skb == NULL) {
203		netdev_warn(sl->dev, "memory squeeze, dropping packet\n");
204		dev->stats.rx_dropped++;
205		return;
206	}
207	skb_push(skb, 1);	/* LAPB internal control */
208	memcpy(skb_put(skb, count), sl->rbuff, count);
209	skb->protocol = x25_type_trans(skb, sl->dev);
210	err = lapb_data_received(skb->dev, skb);
211	if (err != LAPB_OK) {
212		kfree_skb(skb);
213		printk(KERN_DEBUG "x25_asy: data received err - %d\n", err);
214	} else {
215		netif_rx(skb);
216		dev->stats.rx_packets++;
217	}
218}
219
220/* Encapsulate one IP datagram and stuff into a TTY queue. */
221static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
222{
223	unsigned char *p;
224	int actual, count, mtu = sl->dev->mtu;
225
226	if (len > mtu) {
227		/* Sigh, shouldn't occur BUT ... */
228		len = mtu;
229		printk(KERN_DEBUG "%s: truncating oversized transmit packet!\n",
230					sl->dev->name);
231		sl->dev->stats.tx_dropped++;
232		x25_asy_unlock(sl);
233		return;
234	}
235
236	p = icp;
237	count = x25_asy_esc(p, sl->xbuff, len);
238
239	/* Order of next two lines is *very* important.
240	 * When we are sending a little amount of data,
241	 * the transfer may be completed inside driver.write()
242	 * routine, because it's running with interrupts enabled.
243	 * In this case we *never* got WRITE_WAKEUP event,
244	 * if we did not request it before write operation.
245	 *       14 Oct 1994  Dmitry Gorodchanin.
246	 */
247	set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
248	actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
249	sl->xleft = count - actual;
250	sl->xhead = sl->xbuff + actual;
251	/* VSV */
252	clear_bit(SLF_OUTWAIT, &sl->flags);	/* reset outfill flag */
253}
254
255/*
256 * Called by the driver when there's room for more data.  If we have
257 * more packets to send, we send them here.
258 */
259static void x25_asy_write_wakeup(struct tty_struct *tty)
260{
261	int actual;
262	struct x25_asy *sl = tty->disc_data;
263
264	/* First make sure we're connected. */
265	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
266		return;
267
268	if (sl->xleft <= 0) {
269		/* Now serial buffer is almost free & we can start
270		 * transmission of another packet */
271		sl->dev->stats.tx_packets++;
272		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
273		x25_asy_unlock(sl);
274		return;
275	}
276
277	actual = tty->ops->write(tty, sl->xhead, sl->xleft);
278	sl->xleft -= actual;
279	sl->xhead += actual;
280}
281
282static void x25_asy_timeout(struct net_device *dev)
283{
284	struct x25_asy *sl = netdev_priv(dev);
285
286	spin_lock(&sl->lock);
287	if (netif_queue_stopped(dev)) {
288		/* May be we must check transmitter timeout here ?
289		 *      14 Oct 1994 Dmitry Gorodchanin.
290		 */
291		netdev_warn(dev, "transmit timed out, %s?\n",
292			    (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
293			    "bad line quality" : "driver error");
294		sl->xleft = 0;
295		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
296		x25_asy_unlock(sl);
297	}
298	spin_unlock(&sl->lock);
299}
300
301/* Encapsulate an IP datagram and kick it into a TTY queue. */
302
303static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
304				      struct net_device *dev)
305{
306	struct x25_asy *sl = netdev_priv(dev);
307	int err;
308
309	if (!netif_running(sl->dev)) {
310		netdev_err(dev, "xmit call when iface is down\n");
311		kfree_skb(skb);
312		return NETDEV_TX_OK;
313	}
314
315	switch (skb->data[0]) {
316	case X25_IFACE_DATA:
317		break;
318	case X25_IFACE_CONNECT: /* Connection request .. do nothing */
319		err = lapb_connect_request(dev);
320		if (err != LAPB_OK)
321			netdev_err(dev, "lapb_connect_request error: %d\n",
322				   err);
323		kfree_skb(skb);
324		return NETDEV_TX_OK;
325	case X25_IFACE_DISCONNECT: /* do nothing - hang up ?? */
326		err = lapb_disconnect_request(dev);
327		if (err != LAPB_OK)
328			netdev_err(dev, "lapb_disconnect_request error: %d\n",
329				   err);
330	default:
331		kfree_skb(skb);
332		return NETDEV_TX_OK;
333	}
334	skb_pull(skb, 1);	/* Remove control byte */
335	/*
336	 * If we are busy already- too bad.  We ought to be able
337	 * to queue things at this point, to allow for a little
338	 * frame buffer.  Oh well...
339	 * -----------------------------------------------------
340	 * I hate queues in X.25 driver. May be it's efficient,
341	 * but for me latency is more important. ;)
342	 * So, no queues !
343	 *        14 Oct 1994  Dmitry Gorodchanin.
344	 */
345
346	err = lapb_data_request(dev, skb);
347	if (err != LAPB_OK) {
348		netdev_err(dev, "lapb_data_request error: %d\n", err);
349		kfree_skb(skb);
350		return NETDEV_TX_OK;
351	}
352	return NETDEV_TX_OK;
353}
354
355
356/*
357 *	LAPB interface boilerplate
358 */
359
360/*
361 *	Called when I frame data arrives. We did the work above - throw it
362 *	at the net layer.
363 */
364
365static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
366{
367	return netif_rx(skb);
368}
369
370/*
371 *	Data has emerged from the LAPB protocol machine. We don't handle
372 *	busy cases too well. Its tricky to see how to do this nicely -
373 *	perhaps lapb should allow us to bounce this ?
374 */
375
376static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
377{
378	struct x25_asy *sl = netdev_priv(dev);
379
380	spin_lock(&sl->lock);
381	if (netif_queue_stopped(sl->dev) || sl->tty == NULL) {
382		spin_unlock(&sl->lock);
383		netdev_err(dev, "tbusy drop\n");
384		kfree_skb(skb);
385		return;
386	}
387	/* We were not busy, so we are now... :-) */
388	if (skb != NULL) {
389		x25_asy_lock(sl);
390		dev->stats.tx_bytes += skb->len;
391		x25_asy_encaps(sl, skb->data, skb->len);
392		dev_kfree_skb(skb);
393	}
394	spin_unlock(&sl->lock);
395}
396
397/*
398 *	LAPB connection establish/down information.
399 */
400
401static void x25_asy_connected(struct net_device *dev, int reason)
402{
403	struct x25_asy *sl = netdev_priv(dev);
404	struct sk_buff *skb;
405	unsigned char *ptr;
406
407	skb = dev_alloc_skb(1);
408	if (skb == NULL) {
409		netdev_err(dev, "out of memory\n");
410		return;
411	}
412
413	ptr  = skb_put(skb, 1);
414	*ptr = X25_IFACE_CONNECT;
415
416	skb->protocol = x25_type_trans(skb, sl->dev);
417	netif_rx(skb);
418}
419
420static void x25_asy_disconnected(struct net_device *dev, int reason)
421{
422	struct x25_asy *sl = netdev_priv(dev);
423	struct sk_buff *skb;
424	unsigned char *ptr;
425
426	skb = dev_alloc_skb(1);
427	if (skb == NULL) {
428		netdev_err(dev, "out of memory\n");
429		return;
430	}
431
432	ptr  = skb_put(skb, 1);
433	*ptr = X25_IFACE_DISCONNECT;
434
435	skb->protocol = x25_type_trans(skb, sl->dev);
436	netif_rx(skb);
437}
438
439static const struct lapb_register_struct x25_asy_callbacks = {
440	.connect_confirmation = x25_asy_connected,
441	.connect_indication = x25_asy_connected,
442	.disconnect_confirmation = x25_asy_disconnected,
443	.disconnect_indication = x25_asy_disconnected,
444	.data_indication = x25_asy_data_indication,
445	.data_transmit = x25_asy_data_transmit,
446};
447
448
449/* Open the low-level part of the X.25 channel. Easy! */
450static int x25_asy_open(struct net_device *dev)
451{
452	struct x25_asy *sl = netdev_priv(dev);
453	unsigned long len;
454	int err;
455
456	if (sl->tty == NULL)
457		return -ENODEV;
458
459	/*
460	 * Allocate the X.25 frame buffers:
461	 *
462	 * rbuff	Receive buffer.
463	 * xbuff	Transmit buffer.
464	 */
465
466	len = dev->mtu * 2;
467
468	sl->rbuff = kmalloc(len + 4, GFP_KERNEL);
469	if (sl->rbuff == NULL)
470		goto norbuff;
471	sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
472	if (sl->xbuff == NULL)
473		goto noxbuff;
474
475	sl->buffsize = len;
476	sl->rcount   = 0;
477	sl->xleft    = 0;
478	sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
479
480	netif_start_queue(dev);
481
482	/*
483	 *	Now attach LAPB
484	 */
485	err = lapb_register(dev, &x25_asy_callbacks);
486	if (err == LAPB_OK)
487		return 0;
488
489	/* Cleanup */
490	kfree(sl->xbuff);
491noxbuff:
492	kfree(sl->rbuff);
493norbuff:
494	return -ENOMEM;
495}
496
497
498/* Close the low-level part of the X.25 channel. Easy! */
499static int x25_asy_close(struct net_device *dev)
500{
501	struct x25_asy *sl = netdev_priv(dev);
502
503	spin_lock(&sl->lock);
504	if (sl->tty)
505		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
506
507	netif_stop_queue(dev);
508	sl->rcount = 0;
509	sl->xleft  = 0;
510	spin_unlock(&sl->lock);
511	return 0;
512}
513
514/*
515 * Handle the 'receiver data ready' interrupt.
516 * This function is called by the 'tty_io' module in the kernel when
517 * a block of X.25 data has been received, which can now be decapsulated
518 * and sent on to some IP layer for further processing.
519 */
520
521static void x25_asy_receive_buf(struct tty_struct *tty,
522				const unsigned char *cp, char *fp, int count)
523{
524	struct x25_asy *sl = tty->disc_data;
525
526	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
527		return;
528
529
530	/* Read the characters out of the buffer */
531	while (count--) {
532		if (fp && *fp++) {
533			if (!test_and_set_bit(SLF_ERROR, &sl->flags))
534				sl->dev->stats.rx_errors++;
535			cp++;
536			continue;
537		}
538		x25_asy_unesc(sl, *cp++);
539	}
540}
541
542/*
543 * Open the high-level part of the X.25 channel.
544 * This function is called by the TTY module when the
545 * X.25 line discipline is called for.  Because we are
546 * sure the tty line exists, we only have to link it to
547 * a free X.25 channel...
548 */
549
550static int x25_asy_open_tty(struct tty_struct *tty)
551{
552	struct x25_asy *sl = tty->disc_data;
553	int err;
554
555	if (tty->ops->write == NULL)
556		return -EOPNOTSUPP;
557
558	/* First make sure we're not already connected. */
559	if (sl && sl->magic == X25_ASY_MAGIC)
560		return -EEXIST;
561
562	/* OK.  Find a free X.25 channel to use. */
563	sl = x25_asy_alloc();
564	if (sl == NULL)
565		return -ENFILE;
566
567	sl->tty = tty;
568	tty->disc_data = sl;
569	tty->receive_room = 65536;
570	tty_driver_flush_buffer(tty);
571	tty_ldisc_flush(tty);
572
573	/* Restore default settings */
574	sl->dev->type = ARPHRD_X25;
575
576	/* Perform the low-level X.25 async init */
577	err = x25_asy_open(sl->dev);
578	if (err)
579		return err;
580	/* Done.  We have linked the TTY line to a channel. */
581	return 0;
582}
583
584
585/*
586 * Close down an X.25 channel.
587 * This means flushing out any pending queues, and then restoring the
588 * TTY line discipline to what it was before it got hooked to X.25
589 * (which usually is TTY again).
590 */
591static void x25_asy_close_tty(struct tty_struct *tty)
592{
593	struct x25_asy *sl = tty->disc_data;
594	int err;
595
596	/* First make sure we're connected. */
597	if (!sl || sl->magic != X25_ASY_MAGIC)
598		return;
599
600	rtnl_lock();
601	if (sl->dev->flags & IFF_UP)
602		dev_close(sl->dev);
603	rtnl_unlock();
604
605	err = lapb_unregister(sl->dev);
606	if (err != LAPB_OK)
607		pr_err("x25_asy_close: lapb_unregister error: %d\n",
608		       err);
609
610	tty->disc_data = NULL;
611	sl->tty = NULL;
612	x25_asy_free(sl);
613}
614
615 /************************************************************************
616  *			STANDARD X.25 ENCAPSULATION		  	 *
617  ************************************************************************/
618
619static int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
620{
621	unsigned char *ptr = d;
622	unsigned char c;
623
624	/*
625	 * Send an initial END character to flush out any
626	 * data that may have accumulated in the receiver
627	 * due to line noise.
628	 */
629
630	*ptr++ = X25_END;	/* Send 10111110 bit seq */
631
632	/*
633	 * For each byte in the packet, send the appropriate
634	 * character sequence, according to the X.25 protocol.
635	 */
636
637	while (len-- > 0) {
638		switch (c = *s++) {
639		case X25_END:
640			*ptr++ = X25_ESC;
641			*ptr++ = X25_ESCAPE(X25_END);
642			break;
643		case X25_ESC:
644			*ptr++ = X25_ESC;
645			*ptr++ = X25_ESCAPE(X25_ESC);
646			break;
647		default:
648			*ptr++ = c;
649			break;
650		}
651	}
652	*ptr++ = X25_END;
653	return ptr - d;
654}
655
656static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
657{
658
659	switch (s) {
660	case X25_END:
661		if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
662		    sl->rcount > 2)
663			x25_asy_bump(sl);
664		clear_bit(SLF_ESCAPE, &sl->flags);
665		sl->rcount = 0;
666		return;
667	case X25_ESC:
668		set_bit(SLF_ESCAPE, &sl->flags);
669		return;
670	case X25_ESCAPE(X25_ESC):
671	case X25_ESCAPE(X25_END):
672		if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
673			s = X25_UNESCAPE(s);
674		break;
675	}
676	if (!test_bit(SLF_ERROR, &sl->flags)) {
677		if (sl->rcount < sl->buffsize) {
678			sl->rbuff[sl->rcount++] = s;
679			return;
680		}
681		sl->dev->stats.rx_over_errors++;
682		set_bit(SLF_ERROR, &sl->flags);
683	}
684}
685
686
687/* Perform I/O control on an active X.25 channel. */
688static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
689			 unsigned int cmd,  unsigned long arg)
690{
691	struct x25_asy *sl = tty->disc_data;
692
693	/* First make sure we're connected. */
694	if (!sl || sl->magic != X25_ASY_MAGIC)
695		return -EINVAL;
696
697	switch (cmd) {
698	case SIOCGIFNAME:
699		if (copy_to_user((void __user *)arg, sl->dev->name,
700					strlen(sl->dev->name) + 1))
701			return -EFAULT;
702		return 0;
703	case SIOCSIFHWADDR:
704		return -EINVAL;
705	default:
706		return tty_mode_ioctl(tty, file, cmd, arg);
707	}
708}
709
710#ifdef CONFIG_COMPAT
711static long x25_asy_compat_ioctl(struct tty_struct *tty, struct file *file,
712			 unsigned int cmd,  unsigned long arg)
713{
714	switch (cmd) {
715	case SIOCGIFNAME:
716	case SIOCSIFHWADDR:
717		return x25_asy_ioctl(tty, file, cmd,
718				     (unsigned long)compat_ptr(arg));
719	}
720
721	return -ENOIOCTLCMD;
722}
723#endif
724
725static int x25_asy_open_dev(struct net_device *dev)
726{
727	struct x25_asy *sl = netdev_priv(dev);
728	if (sl->tty == NULL)
729		return -ENODEV;
730	return 0;
731}
732
733static const struct net_device_ops x25_asy_netdev_ops = {
734	.ndo_open	= x25_asy_open_dev,
735	.ndo_stop	= x25_asy_close,
736	.ndo_start_xmit	= x25_asy_xmit,
737	.ndo_tx_timeout	= x25_asy_timeout,
738	.ndo_change_mtu	= x25_asy_change_mtu,
739};
740
741/* Initialise the X.25 driver.  Called by the device init code */
742static void x25_asy_setup(struct net_device *dev)
743{
744	struct x25_asy *sl = netdev_priv(dev);
745
746	sl->magic  = X25_ASY_MAGIC;
747	sl->dev	   = dev;
748	spin_lock_init(&sl->lock);
749	set_bit(SLF_INUSE, &sl->flags);
750
751	/*
752	 *	Finish setting up the DEVICE info.
753	 */
754
755	dev->mtu		= SL_MTU;
756	dev->netdev_ops		= &x25_asy_netdev_ops;
757	dev->watchdog_timeo	= HZ*20;
758	dev->hard_header_len	= 0;
759	dev->addr_len		= 0;
760	dev->type		= ARPHRD_X25;
761	dev->tx_queue_len	= 10;
762
763	/* New-style flags. */
764	dev->flags		= IFF_NOARP;
765}
766
767static struct tty_ldisc_ops x25_ldisc = {
768	.owner		= THIS_MODULE,
769	.magic		= TTY_LDISC_MAGIC,
770	.name		= "X.25",
771	.open		= x25_asy_open_tty,
772	.close		= x25_asy_close_tty,
773	.ioctl		= x25_asy_ioctl,
774#ifdef CONFIG_COMPAT
775	.compat_ioctl	= x25_asy_compat_ioctl,
776#endif
777	.receive_buf	= x25_asy_receive_buf,
778	.write_wakeup	= x25_asy_write_wakeup,
779};
780
781static int __init init_x25_asy(void)
782{
783	if (x25_asy_maxdev < 4)
784		x25_asy_maxdev = 4; /* Sanity */
785
786	pr_info("X.25 async: version 0.00 ALPHA (dynamic channels, max=%d)\n",
787		x25_asy_maxdev);
788
789	x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device *),
790				GFP_KERNEL);
791	if (!x25_asy_devs)
792		return -ENOMEM;
793
794	return tty_register_ldisc(N_X25, &x25_ldisc);
795}
796
797
798static void __exit exit_x25_asy(void)
799{
800	struct net_device *dev;
801	int i;
802
803	for (i = 0; i < x25_asy_maxdev; i++) {
804		dev = x25_asy_devs[i];
805		if (dev) {
806			struct x25_asy *sl = netdev_priv(dev);
807
808			spin_lock_bh(&sl->lock);
809			if (sl->tty)
810				tty_hangup(sl->tty);
811
812			spin_unlock_bh(&sl->lock);
813			/*
814			 * VSV = if dev->start==0, then device
815			 * unregistered while close proc.
816			 */
817			unregister_netdev(dev);
818			free_netdev(dev);
819		}
820	}
821
822	kfree(x25_asy_devs);
823	tty_unregister_ldisc(N_X25);
824}
825
826module_init(init_x25_asy);
827module_exit(exit_x25_asy);
828