1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *	Things to sort out:
4 *
5 *	o	tbusy handling
6 *	o	allow users to set the parameters
7 *	o	sync/async switching ?
8 *
9 *	Note: This does _not_ implement CCITT X.25 asynchronous framing
10 *	recommendations. Its primarily for testing purposes. If you wanted
11 *	to do CCITT then in theory all you need is to nick the HDLC async
12 *	checksum routines from ppp.c
13 *      Changes:
14 *
15 *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
16 */
17
18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19
20#include <linux/module.h>
21
22#include <linux/uaccess.h>
23#include <linux/bitops.h>
24#include <linux/string.h>
25#include <linux/mm.h>
26#include <linux/interrupt.h>
27#include <linux/in.h>
28#include <linux/tty.h>
29#include <linux/errno.h>
30#include <linux/netdevice.h>
31#include <linux/etherdevice.h>
32#include <linux/skbuff.h>
33#include <linux/if_arp.h>
34#include <linux/lapb.h>
35#include <linux/init.h>
36#include <linux/rtnetlink.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	len = 2 * newmtu;
128	xbuff = kmalloc(len + 4, GFP_ATOMIC);
129	rbuff = kmalloc(len + 4, GFP_ATOMIC);
130
131	if (xbuff == NULL || rbuff == NULL) {
132		kfree(xbuff);
133		kfree(rbuff);
134		return -ENOMEM;
135	}
136
137	spin_lock_bh(&sl->lock);
138	xbuff    = xchg(&sl->xbuff, xbuff);
139	if (sl->xleft)  {
140		if (sl->xleft <= len)  {
141			memcpy(sl->xbuff, sl->xhead, sl->xleft);
142		} else  {
143			sl->xleft = 0;
144			dev->stats.tx_dropped++;
145		}
146	}
147	sl->xhead = sl->xbuff;
148
149	rbuff	 = xchg(&sl->rbuff, rbuff);
150	if (sl->rcount)  {
151		if (sl->rcount <= len) {
152			memcpy(sl->rbuff, rbuff, sl->rcount);
153		} else  {
154			sl->rcount = 0;
155			dev->stats.rx_over_errors++;
156			set_bit(SLF_ERROR, &sl->flags);
157		}
158	}
159
160	dev->mtu    = newmtu;
161	sl->buffsize = len;
162
163	spin_unlock_bh(&sl->lock);
164
165	kfree(xbuff);
166	kfree(rbuff);
167	return 0;
168}
169
170
171/* Set the "sending" flag.  This must be atomic, hence the ASM. */
172
173static inline void x25_asy_lock(struct x25_asy *sl)
174{
175	netif_stop_queue(sl->dev);
176}
177
178
179/* Clear the "sending" flag.  This must be atomic, hence the ASM. */
180
181static inline void x25_asy_unlock(struct x25_asy *sl)
182{
183	netif_wake_queue(sl->dev);
184}
185
186/* Send an LAPB frame to the LAPB module to process. */
187
188static void x25_asy_bump(struct x25_asy *sl)
189{
190	struct net_device *dev = sl->dev;
191	struct sk_buff *skb;
192	int count;
193	int err;
194
195	count = sl->rcount;
196	dev->stats.rx_bytes += count;
197
198	skb = dev_alloc_skb(count);
199	if (skb == NULL) {
200		netdev_warn(sl->dev, "memory squeeze, dropping packet\n");
201		dev->stats.rx_dropped++;
202		return;
203	}
204	skb_put_data(skb, sl->rbuff, count);
205	err = lapb_data_received(sl->dev, skb);
206	if (err != LAPB_OK) {
207		kfree_skb(skb);
208		printk(KERN_DEBUG "x25_asy: data received err - %d\n", err);
209	} else {
210		dev->stats.rx_packets++;
211	}
212}
213
214/* Encapsulate one IP datagram and stuff into a TTY queue. */
215static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
216{
217	unsigned char *p;
218	int actual, count, mtu = sl->dev->mtu;
219
220	if (len > mtu) {
221		/* Sigh, shouldn't occur BUT ... */
222		len = mtu;
223		printk(KERN_DEBUG "%s: truncating oversized transmit packet!\n",
224					sl->dev->name);
225		sl->dev->stats.tx_dropped++;
226		x25_asy_unlock(sl);
227		return;
228	}
229
230	p = icp;
231	count = x25_asy_esc(p, sl->xbuff, len);
232
233	/* Order of next two lines is *very* important.
234	 * When we are sending a little amount of data,
235	 * the transfer may be completed inside driver.write()
236	 * routine, because it's running with interrupts enabled.
237	 * In this case we *never* got WRITE_WAKEUP event,
238	 * if we did not request it before write operation.
239	 *       14 Oct 1994  Dmitry Gorodchanin.
240	 */
241	set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
242	actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
243	sl->xleft = count - actual;
244	sl->xhead = sl->xbuff + actual;
245}
246
247/*
248 * Called by the driver when there's room for more data.  If we have
249 * more packets to send, we send them here.
250 */
251static void x25_asy_write_wakeup(struct tty_struct *tty)
252{
253	int actual;
254	struct x25_asy *sl = tty->disc_data;
255
256	/* First make sure we're connected. */
257	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
258		return;
259
260	if (sl->xleft <= 0) {
261		/* Now serial buffer is almost free & we can start
262		 * transmission of another packet */
263		sl->dev->stats.tx_packets++;
264		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
265		x25_asy_unlock(sl);
266		return;
267	}
268
269	actual = tty->ops->write(tty, sl->xhead, sl->xleft);
270	sl->xleft -= actual;
271	sl->xhead += actual;
272}
273
274static void x25_asy_timeout(struct net_device *dev, unsigned int txqueue)
275{
276	struct x25_asy *sl = netdev_priv(dev);
277
278	spin_lock(&sl->lock);
279	if (netif_queue_stopped(dev)) {
280		/* May be we must check transmitter timeout here ?
281		 *      14 Oct 1994 Dmitry Gorodchanin.
282		 */
283		netdev_warn(dev, "transmit timed out, %s?\n",
284			    (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
285			    "bad line quality" : "driver error");
286		sl->xleft = 0;
287		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
288		x25_asy_unlock(sl);
289	}
290	spin_unlock(&sl->lock);
291}
292
293/* Encapsulate an IP datagram and kick it into a TTY queue. */
294
295static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
296				      struct net_device *dev)
297{
298	struct x25_asy *sl = netdev_priv(dev);
299	int err;
300
301	if (!netif_running(sl->dev)) {
302		netdev_err(dev, "xmit call when iface is down\n");
303		kfree_skb(skb);
304		return NETDEV_TX_OK;
305	}
306
307	/* There should be a pseudo header of 1 byte added by upper layers.
308	 * Check to make sure it is there before reading it.
309	 */
310	if (skb->len < 1) {
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		fallthrough;
331	default:
332		kfree_skb(skb);
333		return NETDEV_TX_OK;
334	}
335	skb_pull(skb, 1);	/* Remove control byte */
336	/*
337	 * If we are busy already- too bad.  We ought to be able
338	 * to queue things at this point, to allow for a little
339	 * frame buffer.  Oh well...
340	 * -----------------------------------------------------
341	 * I hate queues in X.25 driver. May be it's efficient,
342	 * but for me latency is more important. ;)
343	 * So, no queues !
344	 *        14 Oct 1994  Dmitry Gorodchanin.
345	 */
346
347	err = lapb_data_request(dev, skb);
348	if (err != LAPB_OK) {
349		netdev_err(dev, "lapb_data_request error: %d\n", err);
350		kfree_skb(skb);
351		return NETDEV_TX_OK;
352	}
353	return NETDEV_TX_OK;
354}
355
356
357/*
358 *	LAPB interface boilerplate
359 */
360
361/*
362 *	Called when I frame data arrive. We add a pseudo header for upper
363 *	layers and pass it to upper layers.
364 */
365
366static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
367{
368	if (skb_cow(skb, 1)) {
369		kfree_skb(skb);
370		return NET_RX_DROP;
371	}
372	skb_push(skb, 1);
373	skb->data[0] = X25_IFACE_DATA;
374
375	skb->protocol = x25_type_trans(skb, dev);
376
377	return netif_rx(skb);
378}
379
380/*
381 *	Data has emerged from the LAPB protocol machine. We don't handle
382 *	busy cases too well. Its tricky to see how to do this nicely -
383 *	perhaps lapb should allow us to bounce this ?
384 */
385
386static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
387{
388	struct x25_asy *sl = netdev_priv(dev);
389
390	spin_lock(&sl->lock);
391	if (netif_queue_stopped(sl->dev) || sl->tty == NULL) {
392		spin_unlock(&sl->lock);
393		netdev_err(dev, "tbusy drop\n");
394		kfree_skb(skb);
395		return;
396	}
397	/* We were not busy, so we are now... :-) */
398	if (skb != NULL) {
399		x25_asy_lock(sl);
400		dev->stats.tx_bytes += skb->len;
401		x25_asy_encaps(sl, skb->data, skb->len);
402		dev_kfree_skb(skb);
403	}
404	spin_unlock(&sl->lock);
405}
406
407/*
408 *	LAPB connection establish/down information.
409 */
410
411static void x25_asy_connected(struct net_device *dev, int reason)
412{
413	struct x25_asy *sl = netdev_priv(dev);
414	struct sk_buff *skb;
415	unsigned char *ptr;
416
417	skb = dev_alloc_skb(1);
418	if (skb == NULL) {
419		netdev_err(dev, "out of memory\n");
420		return;
421	}
422
423	ptr  = skb_put(skb, 1);
424	*ptr = X25_IFACE_CONNECT;
425
426	skb->protocol = x25_type_trans(skb, sl->dev);
427	netif_rx(skb);
428}
429
430static void x25_asy_disconnected(struct net_device *dev, int reason)
431{
432	struct x25_asy *sl = netdev_priv(dev);
433	struct sk_buff *skb;
434	unsigned char *ptr;
435
436	skb = dev_alloc_skb(1);
437	if (skb == NULL) {
438		netdev_err(dev, "out of memory\n");
439		return;
440	}
441
442	ptr  = skb_put(skb, 1);
443	*ptr = X25_IFACE_DISCONNECT;
444
445	skb->protocol = x25_type_trans(skb, sl->dev);
446	netif_rx(skb);
447}
448
449static const struct lapb_register_struct x25_asy_callbacks = {
450	.connect_confirmation = x25_asy_connected,
451	.connect_indication = x25_asy_connected,
452	.disconnect_confirmation = x25_asy_disconnected,
453	.disconnect_indication = x25_asy_disconnected,
454	.data_indication = x25_asy_data_indication,
455	.data_transmit = x25_asy_data_transmit,
456};
457
458
459/* Open the low-level part of the X.25 channel. Easy! */
460static int x25_asy_open(struct net_device *dev)
461{
462	struct x25_asy *sl = netdev_priv(dev);
463	unsigned long len;
464
465	if (sl->tty == NULL)
466		return -ENODEV;
467
468	/*
469	 * Allocate the X.25 frame buffers:
470	 *
471	 * rbuff	Receive buffer.
472	 * xbuff	Transmit buffer.
473	 */
474
475	len = dev->mtu * 2;
476
477	sl->rbuff = kmalloc(len + 4, GFP_KERNEL);
478	if (sl->rbuff == NULL)
479		goto norbuff;
480	sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
481	if (sl->xbuff == NULL)
482		goto noxbuff;
483
484	sl->buffsize = len;
485	sl->rcount   = 0;
486	sl->xleft    = 0;
487	sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
488
489	return 0;
490
491	/* Cleanup */
492	kfree(sl->xbuff);
493	sl->xbuff = NULL;
494noxbuff:
495	kfree(sl->rbuff);
496	sl->rbuff = NULL;
497norbuff:
498	return -ENOMEM;
499}
500
501
502/* Close the low-level part of the X.25 channel. Easy! */
503static int x25_asy_close(struct net_device *dev)
504{
505	struct x25_asy *sl = netdev_priv(dev);
506
507	spin_lock(&sl->lock);
508	if (sl->tty)
509		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
510
511	sl->rcount = 0;
512	sl->xleft  = 0;
513	spin_unlock(&sl->lock);
514	return 0;
515}
516
517/*
518 * Handle the 'receiver data ready' interrupt.
519 * This function is called by the 'tty_io' module in the kernel when
520 * a block of X.25 data has been received, which can now be decapsulated
521 * and sent on to some IP layer for further processing.
522 */
523
524static void x25_asy_receive_buf(struct tty_struct *tty,
525				const unsigned char *cp, char *fp, int count)
526{
527	struct x25_asy *sl = 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->dev->stats.rx_errors++;
538			cp++;
539			continue;
540		}
541		x25_asy_unesc(sl, *cp++);
542	}
543}
544
545/*
546 * Open the high-level part of the X.25 channel.
547 * This function is called by the TTY module when the
548 * X.25 line discipline is called for.  Because we are
549 * sure the tty line exists, we only have to link it to
550 * a free X.25 channel...
551 */
552
553static int x25_asy_open_tty(struct tty_struct *tty)
554{
555	struct x25_asy *sl;
556	int err;
557
558	if (tty->ops->write == NULL)
559		return -EOPNOTSUPP;
560
561	/* OK.  Find a free X.25 channel to use. */
562	sl = x25_asy_alloc();
563	if (sl == NULL)
564		return -ENFILE;
565
566	sl->tty = tty;
567	tty->disc_data = sl;
568	tty->receive_room = 65536;
569	tty_driver_flush_buffer(tty);
570	tty_ldisc_flush(tty);
571
572	/* Restore default settings */
573	sl->dev->type = ARPHRD_X25;
574
575	/* Perform the low-level X.25 async init */
576	err = x25_asy_open(sl->dev);
577	if (err) {
578		x25_asy_free(sl);
579		return err;
580	}
581	/* Done.  We have linked the TTY line to a channel. */
582	return 0;
583}
584
585
586/*
587 * Close down an X.25 channel.
588 * This means flushing out any pending queues, and then restoring the
589 * TTY line discipline to what it was before it got hooked to X.25
590 * (which usually is TTY again).
591 */
592static void x25_asy_close_tty(struct tty_struct *tty)
593{
594	struct x25_asy *sl = tty->disc_data;
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	tty->disc_data = NULL;
606	sl->tty = NULL;
607	x25_asy_free(sl);
608}
609
610 /************************************************************************
611  *			STANDARD X.25 ENCAPSULATION		  	 *
612  ************************************************************************/
613
614static int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
615{
616	unsigned char *ptr = d;
617	unsigned char c;
618
619	/*
620	 * Send an initial END character to flush out any
621	 * data that may have accumulated in the receiver
622	 * due to line noise.
623	 */
624
625	*ptr++ = X25_END;	/* Send 10111110 bit seq */
626
627	/*
628	 * For each byte in the packet, send the appropriate
629	 * character sequence, according to the X.25 protocol.
630	 */
631
632	while (len-- > 0) {
633		switch (c = *s++) {
634		case X25_END:
635			*ptr++ = X25_ESC;
636			*ptr++ = X25_ESCAPE(X25_END);
637			break;
638		case X25_ESC:
639			*ptr++ = X25_ESC;
640			*ptr++ = X25_ESCAPE(X25_ESC);
641			break;
642		default:
643			*ptr++ = c;
644			break;
645		}
646	}
647	*ptr++ = X25_END;
648	return ptr - d;
649}
650
651static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
652{
653
654	switch (s) {
655	case X25_END:
656		if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
657		    sl->rcount >= 2)
658			x25_asy_bump(sl);
659		clear_bit(SLF_ESCAPE, &sl->flags);
660		sl->rcount = 0;
661		return;
662	case X25_ESC:
663		set_bit(SLF_ESCAPE, &sl->flags);
664		return;
665	case X25_ESCAPE(X25_ESC):
666	case X25_ESCAPE(X25_END):
667		if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
668			s = X25_UNESCAPE(s);
669		break;
670	}
671	if (!test_bit(SLF_ERROR, &sl->flags)) {
672		if (sl->rcount < sl->buffsize) {
673			sl->rbuff[sl->rcount++] = s;
674			return;
675		}
676		sl->dev->stats.rx_over_errors++;
677		set_bit(SLF_ERROR, &sl->flags);
678	}
679}
680
681
682/* Perform I/O control on an active X.25 channel. */
683static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
684			 unsigned int cmd,  unsigned long arg)
685{
686	struct x25_asy *sl = tty->disc_data;
687
688	/* First make sure we're connected. */
689	if (!sl || sl->magic != X25_ASY_MAGIC)
690		return -EINVAL;
691
692	switch (cmd) {
693	case SIOCGIFNAME:
694		if (copy_to_user((void __user *)arg, sl->dev->name,
695					strlen(sl->dev->name) + 1))
696			return -EFAULT;
697		return 0;
698	case SIOCSIFHWADDR:
699		return -EINVAL;
700	default:
701		return tty_mode_ioctl(tty, file, cmd, arg);
702	}
703}
704
705static int x25_asy_open_dev(struct net_device *dev)
706{
707	int err;
708	struct x25_asy *sl = netdev_priv(dev);
709	if (sl->tty == NULL)
710		return -ENODEV;
711
712	err = lapb_register(dev, &x25_asy_callbacks);
713	if (err != LAPB_OK)
714		return -ENOMEM;
715
716	netif_start_queue(dev);
717
718	return 0;
719}
720
721static int x25_asy_close_dev(struct net_device *dev)
722{
723	int err;
724
725	netif_stop_queue(dev);
726
727	err = lapb_unregister(dev);
728	if (err != LAPB_OK)
729		pr_err("%s: lapb_unregister error: %d\n",
730		       __func__, err);
731
732	x25_asy_close(dev);
733
734	return 0;
735}
736
737static const struct net_device_ops x25_asy_netdev_ops = {
738	.ndo_open	= x25_asy_open_dev,
739	.ndo_stop	= x25_asy_close_dev,
740	.ndo_start_xmit	= x25_asy_xmit,
741	.ndo_tx_timeout	= x25_asy_timeout,
742	.ndo_change_mtu	= x25_asy_change_mtu,
743};
744
745/* Initialise the X.25 driver.  Called by the device init code */
746static void x25_asy_setup(struct net_device *dev)
747{
748	struct x25_asy *sl = netdev_priv(dev);
749
750	sl->magic  = X25_ASY_MAGIC;
751	sl->dev	   = dev;
752	spin_lock_init(&sl->lock);
753	set_bit(SLF_INUSE, &sl->flags);
754
755	/*
756	 *	Finish setting up the DEVICE info.
757	 */
758
759	dev->mtu		= SL_MTU;
760	dev->min_mtu		= 0;
761	dev->max_mtu		= 65534;
762	dev->netdev_ops		= &x25_asy_netdev_ops;
763	dev->watchdog_timeo	= HZ*20;
764	dev->hard_header_len	= 0;
765	dev->addr_len		= 0;
766	dev->type		= ARPHRD_X25;
767	dev->tx_queue_len	= 10;
768
769	/* When transmitting data:
770	 * first this driver removes a pseudo header of 1 byte,
771	 * then the lapb module prepends an LAPB header of at most 3 bytes.
772	 */
773	dev->needed_headroom	= 3 - 1;
774
775	/* New-style flags. */
776	dev->flags		= IFF_NOARP;
777}
778
779static struct tty_ldisc_ops x25_ldisc = {
780	.owner		= THIS_MODULE,
781	.magic		= TTY_LDISC_MAGIC,
782	.name		= "X.25",
783	.open		= x25_asy_open_tty,
784	.close		= x25_asy_close_tty,
785	.ioctl		= x25_asy_ioctl,
786	.receive_buf	= x25_asy_receive_buf,
787	.write_wakeup	= x25_asy_write_wakeup,
788};
789
790static int __init init_x25_asy(void)
791{
792	if (x25_asy_maxdev < 4)
793		x25_asy_maxdev = 4; /* Sanity */
794
795	pr_info("X.25 async: version 0.00 ALPHA (dynamic channels, max=%d)\n",
796		x25_asy_maxdev);
797
798	x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device *),
799				GFP_KERNEL);
800	if (!x25_asy_devs)
801		return -ENOMEM;
802
803	return tty_register_ldisc(N_X25, &x25_ldisc);
804}
805
806
807static void __exit exit_x25_asy(void)
808{
809	struct net_device *dev;
810	int i;
811
812	for (i = 0; i < x25_asy_maxdev; i++) {
813		dev = x25_asy_devs[i];
814		if (dev) {
815			struct x25_asy *sl = netdev_priv(dev);
816
817			spin_lock_bh(&sl->lock);
818			if (sl->tty)
819				tty_hangup(sl->tty);
820
821			spin_unlock_bh(&sl->lock);
822			/*
823			 * VSV = if dev->start==0, then device
824			 * unregistered while close proc.
825			 */
826			unregister_netdev(dev);
827			free_netdev(dev);
828		}
829	}
830
831	kfree(x25_asy_devs);
832	tty_unregister_ldisc(N_X25);
833}
834
835module_init(init_x25_asy);
836module_exit(exit_x25_asy);
837