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#include <linux/module.h>
18
19#include <asm/system.h>
20#include <asm/uaccess.h>
21#include <linux/bitops.h>
22#include <linux/string.h>
23#include <linux/mm.h>
24#include <linux/interrupt.h>
25#include <linux/in.h>
26#include <linux/tty.h>
27#include <linux/errno.h>
28#include <linux/netdevice.h>
29#include <linux/etherdevice.h>
30#include <linux/skbuff.h>
31#include <linux/if_arp.h>
32#include <linux/x25.h>
33#include <linux/lapb.h>
34#include <linux/init.h>
35#include "x25_asy.h"
36
37#include <net/x25device.h>
38
39static struct net_device **x25_asy_devs;
40static int x25_asy_maxdev = SL_NRUNIT;
41
42module_param(x25_asy_maxdev, int, 0);
43MODULE_LICENSE("GPL");
44
45static int x25_asy_esc(unsigned char *p, unsigned char *d, int len);
46static void x25_asy_unesc(struct x25_asy *sl, unsigned char c);
47static void x25_asy_setup(struct net_device *dev);
48
49/* Find a free X.25 channel, and link in this `tty' line. */
50static struct x25_asy *x25_asy_alloc(void)
51{
52	struct net_device *dev = NULL;
53	struct x25_asy *sl;
54	int i;
55
56	if (x25_asy_devs == NULL)
57		return NULL;	/* Master array missing ! */
58
59	for (i = 0; i < x25_asy_maxdev; i++) {
60		dev = x25_asy_devs[i];
61
62		/* Not allocated ? */
63		if (dev == NULL)
64			break;
65
66		sl = dev->priv;
67		/* Not in use ? */
68		if (!test_and_set_bit(SLF_INUSE, &sl->flags))
69			return sl;
70	}
71
72
73	/* Sorry, too many, all slots in use */
74	if (i >= x25_asy_maxdev)
75		return NULL;
76
77	/* If no channels are available, allocate one */
78	if (!dev) {
79		char name[IFNAMSIZ];
80		sprintf(name, "x25asy%d", i);
81
82		dev = alloc_netdev(sizeof(struct x25_asy),
83				   name, x25_asy_setup);
84		if (!dev)
85			return NULL;
86
87		/* Initialize channel control data */
88		sl = dev->priv;
89		dev->base_addr    = i;
90
91		/* register device so that it can be ifconfig'ed       */
92		if (register_netdev(dev) == 0) {
93			/* (Re-)Set the INUSE bit.   Very Important! */
94			set_bit(SLF_INUSE, &sl->flags);
95			x25_asy_devs[i] = dev;
96			return sl;
97		} else {
98			printk("x25_asy_alloc() - register_netdev() failure.\n");
99			free_netdev(dev);
100		}
101	}
102	return NULL;
103}
104
105
106/* Free an X.25 channel. */
107static void x25_asy_free(struct x25_asy *sl)
108{
109	/* Free all X.25 frame buffers. */
110	kfree(sl->rbuff);
111	sl->rbuff = NULL;
112	kfree(sl->xbuff);
113	sl->xbuff = NULL;
114
115	if (!test_and_clear_bit(SLF_INUSE, &sl->flags)) {
116		printk("%s: x25_asy_free for already free unit.\n", sl->dev->name);
117	}
118}
119
120static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
121{
122	struct x25_asy *sl = dev->priv;
123	unsigned char *xbuff, *rbuff;
124	int len = 2* newmtu;
125
126	xbuff = kmalloc(len + 4, GFP_ATOMIC);
127	rbuff = kmalloc(len + 4, GFP_ATOMIC);
128
129	if (xbuff == NULL || rbuff == NULL)
130	{
131		printk("%s: unable to grow X.25 buffers, MTU change cancelled.\n",
132		       dev->name);
133		kfree(xbuff);
134		kfree(rbuff);
135		return -ENOMEM;
136	}
137
138	spin_lock_bh(&sl->lock);
139	xbuff    = xchg(&sl->xbuff, xbuff);
140	if (sl->xleft)  {
141		if (sl->xleft <= len)  {
142			memcpy(sl->xbuff, sl->xhead, sl->xleft);
143		} else  {
144			sl->xleft = 0;
145			sl->stats.tx_dropped++;
146		}
147	}
148	sl->xhead = sl->xbuff;
149
150	rbuff	 = xchg(&sl->rbuff, rbuff);
151	if (sl->rcount)  {
152		if (sl->rcount <= len) {
153			memcpy(sl->rbuff, rbuff, sl->rcount);
154		} else  {
155			sl->rcount = 0;
156			sl->stats.rx_over_errors++;
157			set_bit(SLF_ERROR, &sl->flags);
158		}
159	}
160
161	dev->mtu    = newmtu;
162	sl->buffsize = len;
163
164	spin_unlock_bh(&sl->lock);
165
166	kfree(xbuff);
167	kfree(rbuff);
168	return 0;
169}
170
171
172/* Set the "sending" flag.  This must be atomic, hence the ASM. */
173
174static inline void x25_asy_lock(struct x25_asy *sl)
175{
176	netif_stop_queue(sl->dev);
177}
178
179
180/* Clear the "sending" flag.  This must be atomic, hence the ASM. */
181
182static inline void x25_asy_unlock(struct x25_asy *sl)
183{
184	netif_wake_queue(sl->dev);
185}
186
187/* Send one completely decapsulated IP datagram to the IP layer. */
188
189static void x25_asy_bump(struct x25_asy *sl)
190{
191	struct sk_buff *skb;
192	int count;
193	int err;
194
195	count = sl->rcount;
196	sl->stats.rx_bytes+=count;
197
198	skb = dev_alloc_skb(count+1);
199	if (skb == NULL)
200	{
201		printk("%s: memory squeeze, dropping packet.\n", sl->dev->name);
202		sl->stats.rx_dropped++;
203		return;
204	}
205	skb_push(skb,1);	/* LAPB internal control */
206	memcpy(skb_put(skb,count), sl->rbuff, count);
207	skb->protocol = x25_type_trans(skb, sl->dev);
208	if((err=lapb_data_received(skb->dev, skb))!=LAPB_OK)
209	{
210		kfree_skb(skb);
211		printk(KERN_DEBUG "x25_asy: data received err - %d\n",err);
212	}
213	else
214	{
215		netif_rx(skb);
216		sl->dev->last_rx = jiffies;
217		sl->stats.rx_packets++;
218	}
219}
220
221/* Encapsulate one IP datagram and stuff into a TTY queue. */
222static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
223{
224	unsigned char *p;
225	int actual, count, mtu = sl->dev->mtu;
226
227	if (len > mtu)
228	{		/* Sigh, shouldn't occur BUT ... */
229		len = mtu;
230		printk ("%s: truncating oversized transmit packet!\n", sl->dev->name);
231		sl->stats.tx_dropped++;
232		x25_asy_unlock(sl);
233		return;
234	}
235
236	p = icp;
237	count = x25_asy_esc(p, (unsigned char *) 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	sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
248	actual = sl->tty->driver->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 = (struct x25_asy *) 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	{
270		/* Now serial buffer is almost free & we can start
271		 * transmission of another packet */
272		sl->stats.tx_packets++;
273		tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
274		x25_asy_unlock(sl);
275		return;
276	}
277
278	actual = tty->driver->write(tty, sl->xhead, sl->xleft);
279	sl->xleft -= actual;
280	sl->xhead += actual;
281}
282
283static void x25_asy_timeout(struct net_device *dev)
284{
285	struct x25_asy *sl = (struct x25_asy*)(dev->priv);
286
287	spin_lock(&sl->lock);
288	if (netif_queue_stopped(dev)) {
289		/* May be we must check transmitter timeout here ?
290		 *      14 Oct 1994 Dmitry Gorodchanin.
291		 */
292		printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
293		       (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
294		       "bad line quality" : "driver error");
295		sl->xleft = 0;
296		sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
297		x25_asy_unlock(sl);
298	}
299	spin_unlock(&sl->lock);
300}
301
302/* Encapsulate an IP datagram and kick it into a TTY queue. */
303
304static int x25_asy_xmit(struct sk_buff *skb, struct net_device *dev)
305{
306	struct x25_asy *sl = (struct x25_asy*)(dev->priv);
307	int err;
308
309	if (!netif_running(sl->dev)) {
310		printk("%s: xmit call when iface is down\n", dev->name);
311		kfree_skb(skb);
312		return 0;
313	}
314
315	switch(skb->data[0])
316	{
317		case 0x00:break;
318		case 0x01: /* Connection request .. do nothing */
319			if((err=lapb_connect_request(dev))!=LAPB_OK)
320				printk(KERN_ERR "x25_asy: lapb_connect_request error - %d\n", err);
321			kfree_skb(skb);
322			return 0;
323		case 0x02: /* Disconnect request .. do nothing - hang up ?? */
324			if((err=lapb_disconnect_request(dev))!=LAPB_OK)
325				printk(KERN_ERR "x25_asy: lapb_disconnect_request error - %d\n", err);
326		default:
327			kfree_skb(skb);
328			return  0;
329	}
330	skb_pull(skb,1);	/* Remove control byte */
331	/*
332	 * If we are busy already- too bad.  We ought to be able
333	 * to queue things at this point, to allow for a little
334	 * frame buffer.  Oh well...
335	 * -----------------------------------------------------
336	 * I hate queues in X.25 driver. May be it's efficient,
337	 * but for me latency is more important. ;)
338	 * So, no queues !
339	 *        14 Oct 1994  Dmitry Gorodchanin.
340	 */
341
342	if((err=lapb_data_request(dev,skb))!=LAPB_OK)
343	{
344		printk(KERN_ERR "lapbeth: lapb_data_request error - %d\n", err);
345		kfree_skb(skb);
346		return 0;
347	}
348	return 0;
349}
350
351
352/*
353 *	LAPB interface boilerplate
354 */
355
356/*
357 *	Called when I frame data arrives. We did the work above - throw it
358 *	at the net layer.
359 */
360
361static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
362{
363	skb->dev->last_rx = jiffies;
364	return netif_rx(skb);
365}
366
367/*
368 *	Data has emerged from the LAPB protocol machine. We don't handle
369 *	busy cases too well. Its tricky to see how to do this nicely -
370 *	perhaps lapb should allow us to bounce this ?
371 */
372
373static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
374{
375	struct x25_asy *sl=dev->priv;
376
377	spin_lock(&sl->lock);
378	if (netif_queue_stopped(sl->dev) || sl->tty == NULL)
379	{
380		spin_unlock(&sl->lock);
381		printk(KERN_ERR "x25_asy: tbusy drop\n");
382		kfree_skb(skb);
383		return;
384	}
385	/* We were not busy, so we are now... :-) */
386	if (skb != NULL)
387	{
388		x25_asy_lock(sl);
389		sl->stats.tx_bytes+=skb->len;
390		x25_asy_encaps(sl, skb->data, skb->len);
391		dev_kfree_skb(skb);
392	}
393	spin_unlock(&sl->lock);
394}
395
396/*
397 *	LAPB connection establish/down information.
398 */
399
400static void x25_asy_connected(struct net_device *dev, int reason)
401{
402	struct x25_asy *sl = dev->priv;
403	struct sk_buff *skb;
404	unsigned char *ptr;
405
406	if ((skb = dev_alloc_skb(1)) == NULL) {
407		printk(KERN_ERR "lapbeth: out of memory\n");
408		return;
409	}
410
411	ptr  = skb_put(skb, 1);
412	*ptr = 0x01;
413
414	skb->protocol = x25_type_trans(skb, sl->dev);
415	netif_rx(skb);
416	sl->dev->last_rx = jiffies;
417}
418
419static void x25_asy_disconnected(struct net_device *dev, int reason)
420{
421	struct x25_asy *sl = dev->priv;
422	struct sk_buff *skb;
423	unsigned char *ptr;
424
425	if ((skb = dev_alloc_skb(1)) == NULL) {
426		printk(KERN_ERR "x25_asy: out of memory\n");
427		return;
428	}
429
430	ptr  = skb_put(skb, 1);
431	*ptr = 0x02;
432
433	skb->protocol = x25_type_trans(skb, sl->dev);
434	netif_rx(skb);
435	sl->dev->last_rx = jiffies;
436}
437
438static struct lapb_register_struct x25_asy_callbacks = {
439	.connect_confirmation = x25_asy_connected,
440	.connect_indication = x25_asy_connected,
441	.disconnect_confirmation = x25_asy_disconnected,
442	.disconnect_indication = x25_asy_disconnected,
443	.data_indication = x25_asy_data_indication,
444	.data_transmit = x25_asy_data_transmit,
445
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 = (struct x25_asy*)(dev->priv);
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	}
472	sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
473	if (sl->xbuff == NULL)   {
474		goto noxbuff;
475	}
476
477	sl->buffsize = len;
478	sl->rcount   = 0;
479	sl->xleft    = 0;
480	sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
481
482	netif_start_queue(dev);
483
484	/*
485	 *	Now attach LAPB
486	 */
487	if((err=lapb_register(dev, &x25_asy_callbacks))==LAPB_OK)
488		return 0;
489
490	/* Cleanup */
491	kfree(sl->xbuff);
492noxbuff:
493	kfree(sl->rbuff);
494norbuff:
495	return -ENOMEM;
496}
497
498
499/* Close the low-level part of the X.25 channel. Easy! */
500static int x25_asy_close(struct net_device *dev)
501{
502	struct x25_asy *sl = (struct x25_asy*)(dev->priv);
503	int err;
504
505	spin_lock(&sl->lock);
506	if (sl->tty)
507		sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
508
509	netif_stop_queue(dev);
510	sl->rcount = 0;
511	sl->xleft  = 0;
512	if((err=lapb_unregister(dev))!=LAPB_OK)
513		printk(KERN_ERR "x25_asy_close: lapb_unregister error -%d\n",err);
514	spin_unlock(&sl->lock);
515	return 0;
516}
517
518/*
519 * Handle the 'receiver data ready' interrupt.
520 * This function is called by the 'tty_io' module in the kernel when
521 * a block of X.25 data has been received, which can now be decapsulated
522 * and sent on to some IP layer for further processing.
523 */
524
525static void x25_asy_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
526{
527	struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
528
529	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
530		return;
531
532
533	/* Read the characters out of the buffer */
534	while (count--) {
535		if (fp && *fp++) {
536			if (!test_and_set_bit(SLF_ERROR, &sl->flags))  {
537				sl->stats.rx_errors++;
538			}
539			cp++;
540			continue;
541		}
542		x25_asy_unesc(sl, *cp++);
543	}
544}
545
546/*
547 * Open the high-level part of the X.25 channel.
548 * This function is called by the TTY module when the
549 * X.25 line discipline is called for.  Because we are
550 * sure the tty line exists, we only have to link it to
551 * a free X.25 channel...
552 */
553
554static int x25_asy_open_tty(struct tty_struct *tty)
555{
556	struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
557	int err;
558
559	/* First make sure we're not already connected. */
560	if (sl && sl->magic == X25_ASY_MAGIC) {
561		return -EEXIST;
562	}
563
564	/* OK.  Find a free X.25 channel to use. */
565	if ((sl = x25_asy_alloc()) == NULL) {
566		return -ENFILE;
567	}
568
569	sl->tty = tty;
570	tty->disc_data = sl;
571	tty->receive_room = 65536;
572	if (tty->driver->flush_buffer)  {
573		tty->driver->flush_buffer(tty);
574	}
575	if (tty->ldisc.flush_buffer)  {
576		tty->ldisc.flush_buffer(tty);
577	}
578
579	/* Restore default settings */
580	sl->dev->type = ARPHRD_X25;
581
582	/* Perform the low-level X.25 async init */
583	if ((err = x25_asy_open(sl->dev)))
584		return err;
585
586	/* Done.  We have linked the TTY line to a channel. */
587	return sl->dev->base_addr;
588}
589
590
591/*
592 * Close down an X.25 channel.
593 * This means flushing out any pending queues, and then restoring the
594 * TTY line discipline to what it was before it got hooked to X.25
595 * (which usually is TTY again).
596 */
597static void x25_asy_close_tty(struct tty_struct *tty)
598{
599	struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
600
601	/* First make sure we're connected. */
602	if (!sl || sl->magic != X25_ASY_MAGIC)
603		return;
604
605	if (sl->dev->flags & IFF_UP)
606	{
607		(void) dev_close(sl->dev);
608	}
609
610	tty->disc_data = NULL;
611	sl->tty = NULL;
612	x25_asy_free(sl);
613}
614
615
616static struct net_device_stats *x25_asy_get_stats(struct net_device *dev)
617{
618	struct x25_asy *sl = (struct x25_asy*)(dev->priv);
619
620	return &sl->stats;
621}
622
623
624 /************************************************************************
625  *			STANDARD X.25 ENCAPSULATION		  	 *
626  ************************************************************************/
627
628int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
629{
630	unsigned char *ptr = d;
631	unsigned char c;
632
633	/*
634	 * Send an initial END character to flush out any
635	 * data that may have accumulated in the receiver
636	 * due to line noise.
637	 */
638
639	*ptr++ = X25_END;	/* Send 10111110 bit seq */
640
641	/*
642	 * For each byte in the packet, send the appropriate
643	 * character sequence, according to the X.25 protocol.
644	 */
645
646	while (len-- > 0)
647	{
648		switch(c = *s++)
649		{
650			case X25_END:
651				*ptr++ = X25_ESC;
652				*ptr++ = X25_ESCAPE(X25_END);
653				break;
654			case X25_ESC:
655				*ptr++ = X25_ESC;
656				*ptr++ = X25_ESCAPE(X25_ESC);
657				break;
658			 default:
659				*ptr++ = c;
660				break;
661		}
662	}
663	*ptr++ = X25_END;
664	return (ptr - d);
665}
666
667static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
668{
669
670	switch(s)
671	{
672		case X25_END:
673			if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && (sl->rcount > 2))
674			{
675				x25_asy_bump(sl);
676			}
677			clear_bit(SLF_ESCAPE, &sl->flags);
678			sl->rcount = 0;
679			return;
680
681		case X25_ESC:
682			set_bit(SLF_ESCAPE, &sl->flags);
683			return;
684
685		case X25_ESCAPE(X25_ESC):
686		case X25_ESCAPE(X25_END):
687			if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
688				s = X25_UNESCAPE(s);
689			break;
690	}
691	if (!test_bit(SLF_ERROR, &sl->flags))
692	{
693		if (sl->rcount < sl->buffsize)
694		{
695			sl->rbuff[sl->rcount++] = s;
696			return;
697		}
698		sl->stats.rx_over_errors++;
699		set_bit(SLF_ERROR, &sl->flags);
700	}
701}
702
703
704/* Perform I/O control on an active X.25 channel. */
705static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
706			 unsigned int cmd,  unsigned long arg)
707{
708	struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
709
710	/* First make sure we're connected. */
711	if (!sl || sl->magic != X25_ASY_MAGIC)
712		return -EINVAL;
713
714	switch(cmd) {
715	case SIOCGIFNAME:
716		if (copy_to_user((void __user *)arg, sl->dev->name,
717					strlen(sl->dev->name) + 1))
718			return -EFAULT;
719		return 0;
720	case SIOCSIFHWADDR:
721		return -EINVAL;
722	/* Allow stty to read, but not set, the serial port */
723	case TCGETS:
724	case TCGETA:
725		return n_tty_ioctl(tty, file, cmd, arg);
726	default:
727		return -ENOIOCTLCMD;
728	}
729}
730
731static int x25_asy_open_dev(struct net_device *dev)
732{
733	struct x25_asy *sl = (struct x25_asy*)(dev->priv);
734	if(sl->tty==NULL)
735		return -ENODEV;
736	return 0;
737}
738
739/* Initialise the X.25 driver.  Called by the device init code */
740static void x25_asy_setup(struct net_device *dev)
741{
742	struct x25_asy *sl = dev->priv;
743
744	sl->magic  = X25_ASY_MAGIC;
745	sl->dev	   = dev;
746	spin_lock_init(&sl->lock);
747	set_bit(SLF_INUSE, &sl->flags);
748
749	/*
750	 *	Finish setting up the DEVICE info.
751	 */
752
753	dev->mtu		= SL_MTU;
754	dev->hard_start_xmit	= x25_asy_xmit;
755	dev->tx_timeout		= x25_asy_timeout;
756	dev->watchdog_timeo	= HZ*20;
757	dev->open		= x25_asy_open_dev;
758	dev->stop		= x25_asy_close;
759	dev->get_stats	        = x25_asy_get_stats;
760	dev->change_mtu		= x25_asy_change_mtu;
761	dev->hard_header_len	= 0;
762	dev->addr_len		= 0;
763	dev->type		= ARPHRD_X25;
764	dev->tx_queue_len	= 10;
765
766	/* New-style flags. */
767	dev->flags		= IFF_NOARP;
768}
769
770static struct tty_ldisc x25_ldisc = {
771	.owner		= THIS_MODULE,
772	.magic		= TTY_LDISC_MAGIC,
773	.name		= "X.25",
774	.open		= x25_asy_open_tty,
775	.close		= x25_asy_close_tty,
776	.ioctl		= x25_asy_ioctl,
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	printk(KERN_INFO "X.25 async: version 0.00 ALPHA "
787			"(dynamic channels, max=%d).\n", x25_asy_maxdev );
788
789	x25_asy_devs = kmalloc(sizeof(struct net_device *)*x25_asy_maxdev,
790			       GFP_KERNEL);
791	if (!x25_asy_devs) {
792		printk(KERN_WARNING "X25 async: Can't allocate x25_asy_ctrls[] "
793				"array! Uaargh! (-> No X.25 available)\n");
794		return -ENOMEM;
795	}
796	memset(x25_asy_devs, 0, sizeof(struct net_device *)*x25_asy_maxdev);
797
798	return tty_register_ldisc(N_X25, &x25_ldisc);
799}
800
801
802static void __exit exit_x25_asy(void)
803{
804	struct net_device *dev;
805	int i;
806
807	for (i = 0; i < x25_asy_maxdev; i++) {
808		dev = x25_asy_devs[i];
809		if (dev) {
810			struct x25_asy *sl = dev->priv;
811
812			spin_lock_bh(&sl->lock);
813			if (sl->tty)
814				tty_hangup(sl->tty);
815
816			spin_unlock_bh(&sl->lock);
817			/*
818			 * VSV = if dev->start==0, then device
819			 * unregistered while close proc.
820			 */
821			unregister_netdev(dev);
822			free_netdev(dev);
823		}
824	}
825
826	kfree(x25_asy_devs);
827	tty_unregister_ldisc(N_X25);
828}
829
830module_init(init_x25_asy);
831module_exit(exit_x25_asy);
832