aboutsummaryrefslogtreecommitdiff
path: root/drivers/s390/net/ctctty.c
blob: 9257d60c78330478bca8a05280fda54054ceb9c4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
/*
 * $Id: ctctty.c,v 1.26 2004/08/04 11:06:55 mschwide Exp $
 *
 * CTC / ESCON network driver, tty interface.
 *
 * Copyright (C) 2001 IBM Deutschland Entwicklung GmbH, IBM Corporation
 * Author(s): Fritz Elfert (elfert@de.ibm.com, felfert@millenux.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/serial_reg.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <linux/devfs_fs_kernel.h>
#include "ctctty.h"
#include "ctcdbug.h"

#define CTC_TTY_MAJOR       43
#define CTC_TTY_MAX_DEVICES 64

#define CTC_ASYNC_MAGIC          0x49344C01 /* for paranoia-checking        */
#define CTC_ASYNC_INITIALIZED    0x80000000 /* port was initialized         */
#define CTC_ASYNC_NORMAL_ACTIVE  0x20000000 /* Normal device active         */
#define CTC_ASYNC_CLOSING        0x08000000 /* Serial port is closing       */
#define CTC_ASYNC_CTS_FLOW       0x04000000 /* Do CTS flow control          */
#define CTC_ASYNC_CHECK_CD       0x02000000 /* i.e., CLOCAL                 */
#define CTC_ASYNC_HUP_NOTIFY         0x0001 /* Notify tty on hangups/closes */
#define CTC_ASYNC_NETDEV_OPEN        0x0002 /* Underlying netdev is open    */
#define CTC_ASYNC_TX_LINESTAT        0x0004 /* Must send line status        */
#define CTC_ASYNC_SPLIT_TERMIOS      0x0008 /* Sep. termios for dialin/out  */
#define CTC_TTY_XMIT_SIZE              1024 /* Default bufsize for write    */
#define CTC_SERIAL_XMIT_MAX            4000 /* Maximum bufsize for write    */

/* Private data (similar to async_struct in <linux/serial.h>) */
typedef struct {
  int			magic;
  int			flags;		 /* defined in tty.h               */
  int			mcr;		 /* Modem control register         */
  int                   msr;             /* Modem status register          */
  int                   lsr;             /* Line status register           */
  int			line;
  int			count;		 /* # of fd on device              */
  int			blocked_open;	 /* # of blocked opens             */
  struct net_device     *netdev;
  struct sk_buff_head   tx_queue;        /* transmit queue                 */
  struct sk_buff_head   rx_queue;        /* receive queue                  */
  struct tty_struct 	*tty;            /* Pointer to corresponding tty   */
  wait_queue_head_t	open_wait;
  wait_queue_head_t	close_wait;
  struct semaphore      write_sem;
  struct tasklet_struct tasklet;
  struct timer_list     stoptimer;
} ctc_tty_info;

/* Description of one CTC-tty */
typedef struct {
  struct tty_driver  *ctc_tty_device;		   /* tty-device             */
  ctc_tty_info       info[CTC_TTY_MAX_DEVICES];	   /* Private data           */
} ctc_tty_driver;

static ctc_tty_driver *driver;

/* Leave this unchanged unless you know what you do! */
#define MODEM_PARANOIA_CHECK
#define MODEM_DO_RESTART

#define CTC_TTY_NAME "ctctty"

static __u32 ctc_tty_magic = CTC_ASYNC_MAGIC;
static int ctc_tty_shuttingdown = 0;

static spinlock_t ctc_tty_lock;

/* ctc_tty_try_read() is called from within ctc_tty_rcv_skb()
 * to stuff incoming data directly into a tty's flip-buffer. If the
 * flip buffer is full, the packet gets queued up.
 *
 * Return:
 *  1 = Success
 *  0 = Failure, data has to be buffered and later processed by
 *      ctc_tty_readmodem().
 */
static int
ctc_tty_try_read(ctc_tty_info * info, struct sk_buff *skb)
{
	int c;
	int len;
	struct tty_struct *tty;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if ((tty = info->tty)) {
		if (info->mcr & UART_MCR_RTS) {
			c = TTY_FLIPBUF_SIZE - tty->flip.count;
			len = skb->len;
			if (c >= len) {
				memcpy(tty->flip.char_buf_ptr, skb->data, len);
				memset(tty->flip.flag_buf_ptr, 0, len);
				tty->flip.count += len;
				tty->flip.char_buf_ptr += len;
				tty->flip.flag_buf_ptr += len;
				tty_flip_buffer_push(tty);
				kfree_skb(skb);
				return 1;
			}
		}
	}
	return 0;
}

/* ctc_tty_readmodem() is called periodically from within timer-interrupt.
 * It tries getting received data from the receive queue an stuff it into
 * the tty's flip-buffer.
 */
static int
ctc_tty_readmodem(ctc_tty_info *info)
{
	int ret = 1;
	struct tty_struct *tty;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if ((tty = info->tty)) {
		if (info->mcr & UART_MCR_RTS) {
			int c = TTY_FLIPBUF_SIZE - tty->flip.count;
			struct sk_buff *skb;
			
			if ((c > 0) && (skb = skb_dequeue(&info->rx_queue))) {
				int len = skb->len;
				if (len > c)
					len = c;
				memcpy(tty->flip.char_buf_ptr, skb->data, len);
				skb_pull(skb, len);
				memset(tty->flip.flag_buf_ptr, 0, len);
				tty->flip.count += len;
				tty->flip.char_buf_ptr += len;
				tty->flip.flag_buf_ptr += len;
				tty_flip_buffer_push(tty);
				if (skb->len > 0)
					skb_queue_head(&info->rx_queue, skb);
				else {
					kfree_skb(skb);
					ret = skb_queue_len(&info->rx_queue);
				}
			}
		}
	}
	return ret;
}

void
ctc_tty_setcarrier(struct net_device *netdev, int on)
{
	int i;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if ((!driver) || ctc_tty_shuttingdown)
		return;
	for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
		if (driver->info[i].netdev == netdev) {
			ctc_tty_info *info = &driver->info[i];
			if (on)
				info->msr |= UART_MSR_DCD;
			else
				info->msr &= ~UART_MSR_DCD;
			if ((info->flags & CTC_ASYNC_CHECK_CD) && (!on))
				tty_hangup(info->tty);
		}
}

void
ctc_tty_netif_rx(struct sk_buff *skb)
{
	int i;
	ctc_tty_info *info = NULL;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if (!skb)
		return;
	if ((!skb->dev) || (!driver) || ctc_tty_shuttingdown) {
		dev_kfree_skb(skb);
		return;
	}
	for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
		if (driver->info[i].netdev == skb->dev) {
			info = &driver->info[i];
			break;
		}
	if (!info) {
		dev_kfree_skb(skb);
		return;
	}
	if (skb->len < 6) {
		dev_kfree_skb(skb);
		return;
	}
	if (memcmp(skb->data, &ctc_tty_magic, sizeof(__u32))) {
		dev_kfree_skb(skb);
		return;
	}
	skb_pull(skb, sizeof(__u32));

	i = *((int *)skb->data);
	skb_pull(skb, sizeof(info->mcr));
	if (i & UART_MCR_RTS) {
		info->msr |= UART_MSR_CTS;
		if (info->flags & CTC_ASYNC_CTS_FLOW)
			info->tty->hw_stopped = 0;
	} else {
		info->msr &= ~UART_MSR_CTS;
		if (info->flags & CTC_ASYNC_CTS_FLOW)
			info->tty->hw_stopped = 1;
	}
	if (i & UART_MCR_DTR)
		info->msr |= UART_MSR_DSR;
	else
		info->msr &= ~UART_MSR_DSR;
	if (skb->len <= 0) {
		kfree_skb(skb);
		return;
	}
	/* Try to deliver directly via tty-flip-buf if queue is empty */
	if (skb_queue_empty(&info->rx_queue))
		if (ctc_tty_try_read(info, skb))
			return;
	/* Direct deliver failed or queue wasn't empty.
	 * Queue up for later dequeueing via timer-irq.
	 */
	skb_queue_tail(&info->rx_queue, skb);
	/* Schedule dequeuing */
	tasklet_schedule(&info->tasklet);
}

static int
ctc_tty_tint(ctc_tty_info * info)
{
	struct sk_buff *skb = skb_dequeue(&info->tx_queue);
	int stopped = (info->tty->hw_stopped || info->tty->stopped);
	int wake = 1;
	int rc;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (!info->netdev) {
		if (skb)
			kfree_skb(skb);
		return 0;
	}
	if (info->flags & CTC_ASYNC_TX_LINESTAT) {
		int skb_res = info->netdev->hard_header_len +
			sizeof(info->mcr) + sizeof(__u32);
		/* If we must update line status,
		 * create an empty dummy skb and insert it.
		 */
		if (skb)
			skb_queue_head(&info->tx_queue, skb);

		skb = dev_alloc_skb(skb_res);
		if (!skb) {
			printk(KERN_WARNING
			       "ctc_tty: Out of memory in %s%d tint\n",
			       CTC_TTY_NAME, info->line);
			return 1;
		}
		skb_reserve(skb, skb_res);
		stopped = 0;
		wake = 0;
	}
	if (!skb)
		return 0;
	if (stopped) {
		skb_queue_head(&info->tx_queue, skb);
		return 1;
	}
#if 0
	if (skb->len > 0)
		printk(KERN_DEBUG "tint: %d %02x\n", skb->len, *(skb->data));
	else
		printk(KERN_DEBUG "tint: %d STAT\n", skb->len);
#endif
	memcpy(skb_push(skb, sizeof(info->mcr)), &info->mcr, sizeof(info->mcr));
	memcpy(skb_push(skb, sizeof(__u32)), &ctc_tty_magic, sizeof(__u32));
	rc = info->netdev->hard_start_xmit(skb, info->netdev);
	if (rc) {
		skb_pull(skb, sizeof(info->mcr) + sizeof(__u32));
		if (skb->len > 0)
			skb_queue_head(&info->tx_queue, skb);
		else
			kfree_skb(skb);
	} else {
		struct tty_struct *tty = info->tty;

		info->flags &= ~CTC_ASYNC_TX_LINESTAT;
		if (tty) {
			tty_wakeup(tty);
		}
	}
	return (skb_queue_empty(&info->tx_queue) ? 0 : 1);
}

/************************************************************
 *
 * Modem-functions
 *
 * mostly "stolen" from original Linux-serial.c and friends.
 *
 ************************************************************/

static inline int
ctc_tty_paranoia_check(ctc_tty_info * info, char *name, const char *routine)
{
#ifdef MODEM_PARANOIA_CHECK
	if (!info) {
		printk(KERN_WARNING "ctc_tty: null info_struct for %s in %s\n",
		       name, routine);
		return 1;
	}
	if (info->magic != CTC_ASYNC_MAGIC) {
		printk(KERN_WARNING "ctc_tty: bad magic for info struct %s in %s\n",
		       name, routine);
		return 1;
	}
#endif
	return 0;
}

static void
ctc_tty_inject(ctc_tty_info *info, char c)
{
	int skb_res;
	struct sk_buff *skb;
	
	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_shuttingdown)
		return;
	skb_res = info->netdev->hard_header_len + sizeof(info->mcr) +
		sizeof(__u32) + 1;
	skb = dev_alloc_skb(skb_res);
	if (!skb) {
		printk(KERN_WARNING
		       "ctc_tty: Out of memory in %s%d tx_inject\n",
		       CTC_TTY_NAME, info->line);
		return;
	}
	skb_reserve(skb, skb_res);
	*(skb_put(skb, 1)) = c;
	skb_queue_head(&info->tx_queue, skb);
	tasklet_schedule(&info->tasklet);
}

static void
ctc_tty_transmit_status(ctc_tty_info *info)
{
	DBF_TEXT(trace, 5, __FUNCTION__);
	if (ctc_tty_shuttingdown)
		return;
	info->flags |= CTC_ASYNC_TX_LINESTAT;
	tasklet_schedule(&info->tasklet);
}

static void
ctc_tty_change_speed(ctc_tty_info * info)
{
	unsigned int cflag;
	unsigned int quot;
	int i;

	DBF_TEXT(trace, 3, __FUNCTION__);
	if (!info->tty || !info->tty->termios)
		return;
	cflag = info->tty->termios->c_cflag;

	quot = i = cflag & CBAUD;
	if (i & CBAUDEX) {
		i &= ~CBAUDEX;
		if (i < 1 || i > 2)
			info->tty->termios->c_cflag &= ~CBAUDEX;
		else
			i += 15;
	}
	if (quot) {
		info->mcr |= UART_MCR_DTR;
		info->mcr |= UART_MCR_RTS;
		ctc_tty_transmit_status(info);
	} else {
		info->mcr &= ~UART_MCR_DTR;
		info->mcr &= ~UART_MCR_RTS;
		ctc_tty_transmit_status(info);
		return;
	}

	/* CTS flow control flag and modem status interrupts */
	if (cflag & CRTSCTS) {
		info->flags |= CTC_ASYNC_CTS_FLOW;
	} else
		info->flags &= ~CTC_ASYNC_CTS_FLOW;
	if (cflag & CLOCAL)
		info->flags &= ~CTC_ASYNC_CHECK_CD;
	else {
		info->flags |= CTC_ASYNC_CHECK_CD;
	}
}

static int
ctc_tty_startup(ctc_tty_info * info)
{
	DBF_TEXT(trace, 3, __FUNCTION__);
	if (info->flags & CTC_ASYNC_INITIALIZED)
		return 0;
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "starting up %s%d ...\n", CTC_TTY_NAME, info->line);
#endif
	/*
	 * Now, initialize the UART
	 */
	info->mcr = UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2;
	if (info->tty)
		clear_bit(TTY_IO_ERROR, &info->tty->flags);
	/*
	 * and set the speed of the serial port
	 */
	ctc_tty_change_speed(info);

	info->flags |= CTC_ASYNC_INITIALIZED;
	if (!(info->flags & CTC_ASYNC_NETDEV_OPEN))
		info->netdev->open(info->netdev);
	info->flags |= CTC_ASYNC_NETDEV_OPEN;
	return 0;
}

static void
ctc_tty_stopdev(unsigned long data)
{
	ctc_tty_info *info = (ctc_tty_info *)data;

	if ((!info) || (!info->netdev) ||
	    (info->flags & CTC_ASYNC_INITIALIZED))
		return;
	info->netdev->stop(info->netdev);
	info->flags &= ~CTC_ASYNC_NETDEV_OPEN;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void
ctc_tty_shutdown(ctc_tty_info * info)
{
	DBF_TEXT(trace, 3, __FUNCTION__);
	if (!(info->flags & CTC_ASYNC_INITIALIZED))
		return;
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "Shutting down %s%d ....\n", CTC_TTY_NAME, info->line);
#endif
	info->msr &= ~UART_MSR_RI;
	if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
		info->mcr &= ~(UART_MCR_DTR | UART_MCR_RTS);
	if (info->tty)
		set_bit(TTY_IO_ERROR, &info->tty->flags);
	mod_timer(&info->stoptimer, jiffies + (10 * HZ));
	skb_queue_purge(&info->tx_queue);
	skb_queue_purge(&info->rx_queue);
	info->flags &= ~CTC_ASYNC_INITIALIZED;
}

/* ctc_tty_write() is the main send-routine. It is called from the upper
 * levels within the kernel to perform sending data. Depending on the
 * online-flag it either directs output to the at-command-interpreter or
 * to the lower level. Additional tasks done here:
 *  - If online, check for escape-sequence (+++)
 *  - If sending audio-data, call ctc_tty_DLEdown() to parse DLE-codes.
 *  - If receiving audio-data, call ctc_tty_end_vrx() to abort if needed.
 *  - If dialing, abort dial.
 */
static int
ctc_tty_write(struct tty_struct *tty, const u_char * buf, int count)
{
	int c;
	int total = 0;
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	DBF_TEXT(trace, 5, __FUNCTION__);
	if (ctc_tty_shuttingdown)
		goto ex;
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_write"))
		goto ex;
	if (!tty)
		goto ex;
	if (!info->netdev) {
		total = -ENODEV;
		goto ex;
	}
	while (1) {
		struct sk_buff *skb;
		int skb_res;

		c = (count < CTC_TTY_XMIT_SIZE) ? count : CTC_TTY_XMIT_SIZE;
		if (c <= 0)
			break;
		
		skb_res = info->netdev->hard_header_len + sizeof(info->mcr) +
			+ sizeof(__u32);
		skb = dev_alloc_skb(skb_res + c);
		if (!skb) {
			printk(KERN_WARNING
			       "ctc_tty: Out of memory in %s%d write\n",
			       CTC_TTY_NAME, info->line);
			break;
		}
		skb_reserve(skb, skb_res);
		memcpy(skb_put(skb, c), buf, c);
		skb_queue_tail(&info->tx_queue, skb);
		buf += c;
		total += c;
		count -= c;
	}
	if (skb_queue_len(&info->tx_queue)) {
		info->lsr &= ~UART_LSR_TEMT;
		tasklet_schedule(&info->tasklet);
	}
ex:
	DBF_TEXT(trace, 6, __FUNCTION__);
	return total;
}

static int
ctc_tty_write_room(struct tty_struct *tty)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_write_room"))
		return 0;
	return CTC_TTY_XMIT_SIZE;
}

static int
ctc_tty_chars_in_buffer(struct tty_struct *tty)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_chars_in_buffer"))
		return 0;
	return 0;
}

static void
ctc_tty_flush_buffer(struct tty_struct *tty)
{
	ctc_tty_info *info;
	unsigned long flags;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (!tty)
		goto ex;
	spin_lock_irqsave(&ctc_tty_lock, flags);
	info = (ctc_tty_info *) tty->driver_data;
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_flush_buffer")) {
		spin_unlock_irqrestore(&ctc_tty_lock, flags);
		goto ex;
	}
	skb_queue_purge(&info->tx_queue);
	info->lsr |= UART_LSR_TEMT;
	spin_unlock_irqrestore(&ctc_tty_lock, flags);
	wake_up_interruptible(&tty->write_wait);
	tty_wakeup(tty);
ex:
	DBF_TEXT_(trace, 2, "ex: %s ", __FUNCTION__);
	return;
}

static void
ctc_tty_flush_chars(struct tty_struct *tty)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_shuttingdown)
		return;
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_flush_chars"))
		return;
	if (tty->stopped || tty->hw_stopped || (!skb_queue_len(&info->tx_queue)))
		return;
	tasklet_schedule(&info->tasklet);
}

/*
 * ------------------------------------------------------------
 * ctc_tty_throttle()
 *
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void
ctc_tty_throttle(struct tty_struct *tty)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_throttle"))
		return;
	info->mcr &= ~UART_MCR_RTS;
	if (I_IXOFF(tty))
		ctc_tty_inject(info, STOP_CHAR(tty));
	ctc_tty_transmit_status(info);
}

static void
ctc_tty_unthrottle(struct tty_struct *tty)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_unthrottle"))
		return;
	info->mcr |= UART_MCR_RTS;
	if (I_IXOFF(tty))
		ctc_tty_inject(info, START_CHAR(tty));
	ctc_tty_transmit_status(info);
}

/*
 * ------------------------------------------------------------
 * ctc_tty_ioctl() and friends
 * ------------------------------------------------------------
 */

/*
 * ctc_tty_get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *          is emptied.  On bus types like RS485, the transmitter must
 *          release the bus after transmitting. This must be done when
 *          the transmit shift register is empty, not be done when the
 *          transmit holding register is empty.  This functionality
 *          allows RS485 driver to be written in user space.
 */
static int
ctc_tty_get_lsr_info(ctc_tty_info * info, uint __user *value)
{
	u_char status;
	uint result;
	ulong flags;

	DBF_TEXT(trace, 4, __FUNCTION__);
	spin_lock_irqsave(&ctc_tty_lock, flags);
	status = info->lsr;
	spin_unlock_irqrestore(&ctc_tty_lock, flags);
	result = ((status & UART_LSR_TEMT) ? TIOCSER_TEMT : 0);
	put_user(result, value);
	return 0;
}


static int ctc_tty_tiocmget(struct tty_struct *tty, struct file *file)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
	u_char control,
	 status;
	uint result;
	ulong flags;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_ioctl"))
		return -ENODEV;
	if (tty->flags & (1 << TTY_IO_ERROR))
		return -EIO;

	control = info->mcr;
	spin_lock_irqsave(&ctc_tty_lock, flags);
	status = info->msr;
	spin_unlock_irqrestore(&ctc_tty_lock, flags);
	result = ((control & UART_MCR_RTS) ? TIOCM_RTS : 0)
	    | ((control & UART_MCR_DTR) ? TIOCM_DTR : 0)
	    | ((status & UART_MSR_DCD) ? TIOCM_CAR : 0)
	    | ((status & UART_MSR_RI) ? TIOCM_RNG : 0)
	    | ((status & UART_MSR_DSR) ? TIOCM_DSR : 0)
	    | ((status & UART_MSR_CTS) ? TIOCM_CTS : 0);
	return result;
}

static int
ctc_tty_tiocmset(struct tty_struct *tty, struct file *file,
		 unsigned int set, unsigned int clear)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_ioctl"))
		return -ENODEV;
	if (tty->flags & (1 << TTY_IO_ERROR))
		return -EIO;

	if (set & TIOCM_RTS)
		info->mcr |= UART_MCR_RTS;
	if (set & TIOCM_DTR)
		info->mcr |= UART_MCR_DTR;

	if (clear & TIOCM_RTS)
		info->mcr &= ~UART_MCR_RTS;
	if (clear & TIOCM_DTR)
		info->mcr &= ~UART_MCR_DTR;

	if ((set | clear) & (TIOCM_RTS|TIOCM_DTR))
		ctc_tty_transmit_status(info);
	return 0;
}

static int
ctc_tty_ioctl(struct tty_struct *tty, struct file *file,
	       uint cmd, ulong arg)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
	int error;
	int retval;

	DBF_TEXT(trace, 4, __FUNCTION__);
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_ioctl"))
		return -ENODEV;
	if (tty->flags & (1 << TTY_IO_ERROR))
		return -EIO;
	switch (cmd) {
		case TCSBRK:   /* SVID version: non-zero arg --> no break */
#ifdef CTC_DEBUG_MODEM_IOCTL
			printk(KERN_DEBUG "%s%d ioctl TCSBRK\n", CTC_TTY_NAME, info->line);
#endif
			retval = tty_check_change(tty);
			if (retval)
				return retval;
			tty_wait_until_sent(tty, 0);
			return 0;
		case TCSBRKP:  /* support for POSIX tcsendbreak() */
#ifdef CTC_DEBUG_MODEM_IOCTL
			printk(KERN_DEBUG "%s%d ioctl TCSBRKP\n", CTC_TTY_NAME, info->line);
#endif
			retval = tty_check_change(tty);
			if (retval)
				return retval;
			tty_wait_until_sent(tty, 0);
			return 0;
		case TIOCGSOFTCAR:
#ifdef CTC_DEBUG_MODEM_IOCTL
			printk(KERN_DEBUG "%s%d ioctl TIOCGSOFTCAR\n", CTC_TTY_NAME,
			       info->line);
#endif
			error = put_user(C_CLOCAL(tty) ? 1 : 0, (ulong __user *) arg);
			return error;
		case TIOCSSOFTCAR:
#ifdef CTC_DEBUG_MODEM_IOCTL
			printk(KERN_DEBUG "%s%d ioctl TIOCSSOFTCAR\n", CTC_TTY_NAME,
			       info->line);
#endif
			error = get_user(arg, (ulong __user *) arg);
			if (error)
				return error;
			tty->termios->c_cflag =
			    ((tty->termios->c_cflag & ~CLOCAL) |
			     (arg ? CLOCAL : 0));
			return 0;
		case TIOCSERGETLSR:	/* Get line status register */
#ifdef CTC_DEBUG_MODEM_IOCTL
			printk(KERN_DEBUG "%s%d ioctl TIOCSERGETLSR\n", CTC_TTY_NAME,
			       info->line);
#endif
			if (access_ok(VERIFY_WRITE, (void __user *) arg, sizeof(uint)))
				return ctc_tty_get_lsr_info(info, (uint __user *) arg);
			else
				return -EFAULT;
		default:
#ifdef CTC_DEBUG_MODEM_IOCTL
			printk(KERN_DEBUG "UNKNOWN ioctl 0x%08x on %s%d\n", cmd,
			       CTC_TTY_NAME, info->line);
#endif
			return -ENOIOCTLCMD;
	}
	return 0;
}

static void
ctc_tty_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
	unsigned int cflag = tty->termios->c_cflag;

	DBF_TEXT(trace, 4, __FUNCTION__);
	ctc_tty_change_speed(info);

	/* Handle transition to B0 */
	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD)) {
		info->mcr &= ~(UART_MCR_DTR|UART_MCR_RTS);
		ctc_tty_transmit_status(info);
	}

	/* Handle transition from B0 to other */
	if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
		info->mcr |= UART_MCR_DTR;
		if (!(tty->termios->c_cflag & CRTSCTS) ||
                    !test_bit(TTY_THROTTLED, &tty->flags)) {
                        info->mcr |= UART_MCR_RTS;
                }
		ctc_tty_transmit_status(info);
	}

	/* Handle turning off CRTSCTS */
	if ((old_termios->c_cflag & CRTSCTS) &&
            !(tty->termios->c_cflag & CRTSCTS))
                tty->hw_stopped = 0;
}

/*
 * ------------------------------------------------------------
 * ctc_tty_open() and friends
 * ------------------------------------------------------------
 */
static int
ctc_tty_block_til_ready(struct tty_struct *tty, struct file *filp, ctc_tty_info *info)
{
	DECLARE_WAITQUEUE(wait, NULL);
	int do_clocal = 0;
	unsigned long flags;
	int retval;

	DBF_TEXT(trace, 4, __FUNCTION__);
	/*
	 * If the device is in the middle of being closed, then block
	 * until it's done, and then try again.
	 */
	if (tty_hung_up_p(filp) ||
	    (info->flags & CTC_ASYNC_CLOSING)) {
		if (info->flags & CTC_ASYNC_CLOSING)
			wait_event(info->close_wait, 
				   !(info->flags & CTC_ASYNC_CLOSING));
#ifdef MODEM_DO_RESTART
		if (info->flags & CTC_ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -ERESTARTSYS;
#else
		return -EAGAIN;
#endif
	}
	/*
	 * If non-blocking mode is set, then make the check up front
	 * and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		info->flags |= CTC_ASYNC_NORMAL_ACTIVE;
		return 0;
	}
	if (tty->termios->c_cflag & CLOCAL)
		do_clocal = 1;
	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, info->count is dropped by one, so that
	 * ctc_tty_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;
	add_wait_queue(&info->open_wait, &wait);
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "ctc_tty_block_til_ready before block: %s%d, count = %d\n",
	       CTC_TTY_NAME, info->line, info->count);
#endif
	spin_lock_irqsave(&ctc_tty_lock, flags);
	if (!(tty_hung_up_p(filp)))
		info->count--;
	spin_unlock_irqrestore(&ctc_tty_lock, flags);
	info->blocked_open++;
	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(info->flags & CTC_ASYNC_INITIALIZED)) {
#ifdef MODEM_DO_RESTART
			if (info->flags & CTC_ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;
#else
			retval = -EAGAIN;
#endif
			break;
		}
		if (!(info->flags & CTC_ASYNC_CLOSING) &&
		    (do_clocal || (info->msr & UART_MSR_DCD))) {
			break;
		}
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
#ifdef CTC_DEBUG_MODEM_OPEN
		printk(KERN_DEBUG "ctc_tty_block_til_ready blocking: %s%d, count = %d\n",
		       CTC_TTY_NAME, info->line, info->count);
#endif
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&info->open_wait, &wait);
	if (!tty_hung_up_p(filp))
		info->count++;
	info->blocked_open--;
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "ctc_tty_block_til_ready after blocking: %s%d, count = %d\n",
	       CTC_TTY_NAME, info->line, info->count);
#endif
	if (retval)
		return retval;
	info->flags |= CTC_ASYNC_NORMAL_ACTIVE;
	return 0;
}

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its async structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
static int
ctc_tty_open(struct tty_struct *tty, struct file *filp)
{
	ctc_tty_info *info;
	unsigned long saveflags;
	int retval,
	 line;

	DBF_TEXT(trace, 3, __FUNCTION__);
	line = tty->index;
	if (line < 0 || line > CTC_TTY_MAX_DEVICES)
		return -ENODEV;
	info = &driver->info[line];
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_open"))
		return -ENODEV;
	if (!info->netdev)
		return -ENODEV;
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "ctc_tty_open %s, count = %d\n", tty->name,
	       info->count);
#endif
	spin_lock_irqsave(&ctc_tty_lock, saveflags);
	info->count++;
	tty->driver_data = info;
	info->tty = tty;
	spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
	/*
	 * Start up serial port
	 */
	retval = ctc_tty_startup(info);
	if (retval) {
#ifdef CTC_DEBUG_MODEM_OPEN
		printk(KERN_DEBUG "ctc_tty_open return after startup\n");
#endif
		return retval;
	}
	retval = ctc_tty_block_til_ready(tty, filp, info);
	if (retval) {
#ifdef CTC_DEBUG_MODEM_OPEN
		printk(KERN_DEBUG "ctc_tty_open return after ctc_tty_block_til_ready \n");
#endif
		return retval;
	}
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "ctc_tty_open %s successful...\n", tty->name);
#endif
	return 0;
}

static void
ctc_tty_close(struct tty_struct *tty, struct file *filp)
{
	ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
	ulong flags;
	ulong timeout;
	DBF_TEXT(trace, 3, __FUNCTION__);
	if (!info || ctc_tty_paranoia_check(info, tty->name, "ctc_tty_close"))
		return;
	spin_lock_irqsave(&ctc_tty_lock, flags);
	if (tty_hung_up_p(filp)) {
		spin_unlock_irqrestore(&ctc_tty_lock, flags);
#ifdef CTC_DEBUG_MODEM_OPEN
		printk(KERN_DEBUG "ctc_tty_close return after tty_hung_up_p\n");
#endif
		return;
	}
	if ((tty->count == 1) && (info->count != 1)) {
		/*
		 * Uh, oh.  tty->count is 1, which means that the tty
		 * structure will be freed.  Info->count should always
		 * be one in these conditions.  If it's greater than
		 * one, we've got real problems, since it means the
		 * serial port won't be shutdown.
		 */
		printk(KERN_ERR "ctc_tty_close: bad port count; tty->count is 1, "
		       "info->count is %d\n", info->count);
		info->count = 1;
	}
	if (--info->count < 0) {
		printk(KERN_ERR "ctc_tty_close: bad port count for %s%d: %d\n",
		       CTC_TTY_NAME, info->line, info->count);
		info->count = 0;
	}
	if (info->count) {
		local_irq_restore(flags);
#ifdef CTC_DEBUG_MODEM_OPEN
		printk(KERN_DEBUG "ctc_tty_close after info->count != 0\n");
#endif
		return;
	}
	info->flags |= CTC_ASYNC_CLOSING;
	tty->closing = 1;
	/*
	 * At this point we stop accepting input.  To do this, we
	 * disable the receive line status interrupts, and tell the
	 * interrupt driver to stop checking the data ready bit in the
	 * line status register.
	 */
	if (info->flags & CTC_ASYNC_INITIALIZED) {
		tty_wait_until_sent(tty, 30*HZ); /* 30 seconds timeout */
		/*
		 * Before we drop DTR, make sure the UART transmitter
		 * has completely drained; this is especially
		 * important if there is a transmit FIFO!
		 */
		timeout = jiffies + HZ;
		while (!(info->lsr & UART_LSR_TEMT)) {
			spin_unlock_irqrestore(&ctc_tty_lock, flags);
			msleep(500);
			spin_lock_irqsave(&ctc_tty_lock, flags);
			if (time_after(jiffies,timeout))
				break;
		}
	}
	ctc_tty_shutdown(info);
	if (tty->driver->flush_buffer) {
		skb_queue_purge(&info->tx_queue);
		info->lsr |= UART_LSR_TEMT;
	}
	tty_ldisc_flush(tty);
	info->tty = 0;
	tty->closing = 0;
	if (info->blocked_open) {
		set_current_state(TASK_INTERRUPTIBLE);
		schedule_timeout(HZ/2);
		wake_up_interruptible(&info->open_wait);
	}
	info->flags &= ~(CTC_ASYNC_NORMAL_ACTIVE | CTC_ASYNC_CLOSING);
	wake_up_interruptible(&info->close_wait);
	spin_unlock_irqrestore(&ctc_tty_lock, flags);
#ifdef CTC_DEBUG_MODEM_OPEN
	printk(KERN_DEBUG "ctc_tty_close normal exit\n");
#endif
}

/*
 * ctc_tty_hangup() --- called by tty_hangup() when a hangup is signaled.
 */
static void
ctc_tty_hangup(struct tty_struct *tty)
{
	ctc_tty_info *info = (ctc_tty_info *)tty->driver_data;
	unsigned long saveflags;
	DBF_TEXT(trace, 3, __FUNCTION__);
	if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_hangup"))
		return;
	ctc_tty_shutdown(info);
	info->count = 0;
	info->flags &= ~CTC_ASYNC_NORMAL_ACTIVE;
	spin_lock_irqsave(&ctc_tty_lock, saveflags);
	info->tty = 0;
	spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
	wake_up_interruptible(&info->open_wait);
}


/*
 * For all online tty's, try sending data to
 * the lower levels.
 */
static void
ctc_tty_task(unsigned long arg)
{
	ctc_tty_info *info = (void *)arg;
	unsigned long saveflags;
	int again;

	DBF_TEXT(trace, 3, __FUNCTION__);
	spin_lock_irqsave(&ctc_tty_lock, saveflags);
	if ((!ctc_tty_shuttingdown) && info) {
		again = ctc_tty_tint(info);
		if (!again)
			info->lsr |= UART_LSR_TEMT;
		again |= ctc_tty_readmodem(info);
		if (again) {
			tasklet_schedule(&info->tasklet);
		}
	}
	spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
}

static struct tty_operations ctc_ops = {
	.open = ctc_tty_open,
	.close = ctc_tty_close,
	.write = ctc_tty_write,
	.flush_chars = ctc_tty_flush_chars,
	.write_room = ctc_tty_write_room,
	.chars_in_buffer = ctc_tty_chars_in_buffer,
	.flush_buffer = ctc_tty_flush_buffer,
	.ioctl = ctc_tty_ioctl,
	.throttle = ctc_tty_throttle,
	.unthrottle = ctc_tty_unthrottle,
	.set_termios = ctc_tty_set_termios,
	.hangup = ctc_tty_hangup,
	.tiocmget = ctc_tty_tiocmget,
	.tiocmset = ctc_tty_tiocmset,
};

int
ctc_tty_init(void)
{
	int i;
	ctc_tty_info *info;
	struct tty_driver *device;

	DBF_TEXT(trace, 2, __FUNCTION__);
	driver = kmalloc(sizeof(ctc_tty_driver), GFP_KERNEL);
	if (driver == NULL) {
		printk(KERN_WARNING "Out of memory in ctc_tty_modem_init\n");
		return -ENOMEM;
	}
	memset(driver, 0, sizeof(ctc_tty_driver));
	device = alloc_tty_driver(CTC_TTY_MAX_DEVICES);
	if (!device) {
		kfree(driver);
		printk(KERN_WARNING "Out of memory in ctc_tty_modem_init\n");
		return -ENOMEM;
	}

	device->devfs_name = "ctc/" CTC_TTY_NAME;
	device->name = CTC_TTY_NAME;
	device->major = CTC_TTY_MAJOR;
	device->minor_start = 0;
	device->type = TTY_DRIVER_TYPE_SERIAL;
	device->subtype = SERIAL_TYPE_NORMAL;
	device->init_termios = tty_std_termios;
	device->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	device->flags = TTY_DRIVER_REAL_RAW;
	device->driver_name = "ctc_tty",
	tty_set_operations(device, &ctc_ops);
	if (tty_register_driver(device)) {
		printk(KERN_WARNING "ctc_tty: Couldn't register serial-device\n");
		put_tty_driver(device);
		kfree(driver);
		return -1;
	}
	driver->ctc_tty_device = device;
	for (i = 0; i < CTC_TTY_MAX_DEVICES; i++) {
		info = &driver->info[i];
		init_MUTEX(&info->write_sem);
		tasklet_init(&info->tasklet, ctc_tty_task,
				(unsigned long) info);
		info->magic = CTC_ASYNC_MAGIC;
		info->line = i;
		info->tty = 0;
		info->count = 0;
		info->blocked_open = 0;
		init_waitqueue_head(&info->open_wait);
		init_waitqueue_head(&info->close_wait);
		skb_queue_head_init(&info->tx_queue);
		skb_queue_head_init(&info->rx_queue);
		init_timer(&info->stoptimer);
		info->stoptimer.function = ctc_tty_stopdev;
		info->stoptimer.data = (unsigned long)info;
		info->mcr = UART_MCR_RTS;
	}
	return 0;
}

int
ctc_tty_register_netdev(struct net_device *dev) {
	int ttynum;
	char *err;
	char *p;

	DBF_TEXT(trace, 2, __FUNCTION__);
	if ((!dev) || (!dev->name)) {
		printk(KERN_WARNING
		       "ctc_tty_register_netdev called "
		       "with NULL dev or NULL dev-name\n");
		return -1;
	}

	/*
	 *	If the name is a format string the caller wants us to
	 *	do a name allocation : format string must end with %d
	 */
	if (strchr(dev->name, '%'))
	{
		int err = dev_alloc_name(dev, dev->name);	// dev->name is changed by this
		if (err < 0) {
			printk(KERN_DEBUG "dev_alloc returned error %d\n", err);
			return err;
		}

	}

	for (p = dev->name; p && ((*p < '0') || (*p > '9')); p++);
	ttynum = simple_strtoul(p, &err, 0);
	if ((ttynum < 0) || (ttynum >= CTC_TTY_MAX_DEVICES) ||
	    (err && *err)) {
		printk(KERN_WARNING
		       "ctc_tty_register_netdev called "
		       "with number in name '%s'\n", dev->name);
		return -1;
	}
	if (driver->info[ttynum].netdev) {
		printk(KERN_WARNING
		       "ctc_tty_register_netdev called "
		       "for already registered device '%s'\n",
		       dev->name);
		return -1;
	}
	driver->info[ttynum].netdev = dev;
	return 0;
}

void
ctc_tty_unregister_netdev(struct net_device *dev) {
	int i;
	unsigned long saveflags;
	ctc_tty_info *info = NULL;

	DBF_TEXT(trace, 2, __FUNCTION__);
	spin_lock_irqsave(&ctc_tty_lock, saveflags);
	for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
		if (driver->info[i].netdev == dev) {
			info = &driver->info[i];
			break;
		}
	if (info) {
		info->netdev = NULL;
		skb_queue_purge(&info->tx_queue);
		skb_queue_purge(&info->rx_queue);
	}
	spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
}

void
ctc_tty_cleanup(void) {
	unsigned long saveflags;
	
	DBF_TEXT(trace, 2, __FUNCTION__);
	spin_lock_irqsave(&ctc_tty_lock, saveflags);
	ctc_tty_shuttingdown = 1;
	spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
	tty_unregister_driver(driver->ctc_tty_device);
	put_tty_driver(driver->ctc_tty_device);
	kfree(driver);
	driver = NULL;
}