aboutsummaryrefslogtreecommitdiff
path: root/drivers/usb/atm/usbatm.c
blob: d3448ca110cecf4ccdb47cba2d296fc720041bfc (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
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
/******************************************************************************
 *  usbatm.c - Generic USB xDSL driver core
 *
 *  Copyright (C) 2001, Alcatel
 *  Copyright (C) 2003, Duncan Sands, SolNegro, Josep Comas
 *  Copyright (C) 2004, David Woodhouse, Roman Kagan
 *
 *  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 of the License, 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., 59
 *  Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 ******************************************************************************/

/*
 *  Written by Johan Verrept, Duncan Sands (duncan.sands@free.fr) and David Woodhouse
 *
 *  1.7+:	- See the check-in logs
 *
 *  1.6:	- No longer opens a connection if the firmware is not loaded
 *  		- Added support for the speedtouch 330
 *  		- Removed the limit on the number of devices
 *  		- Module now autoloads on device plugin
 *  		- Merged relevant parts of sarlib
 *  		- Replaced the kernel thread with a tasklet
 *  		- New packet transmission code
 *  		- Changed proc file contents
 *  		- Fixed all known SMP races
 *  		- Many fixes and cleanups
 *  		- Various fixes by Oliver Neukum (oliver@neukum.name)
 *
 *  1.5A:	- Version for inclusion in 2.5 series kernel
 *		- Modifications by Richard Purdie (rpurdie@rpsys.net)
 *		- made compatible with kernel 2.5.6 onwards by changing
 *		usbatm_usb_send_data_context->urb to a pointer and adding code
 *		to alloc and free it
 *		- remove_wait_queue() added to usbatm_atm_processqueue_thread()
 *
 *  1.5:	- fixed memory leak when atmsar_decode_aal5 returned NULL.
 *		(reported by stephen.robinson@zen.co.uk)
 *
 *  1.4:	- changed the spin_lock() under interrupt to spin_lock_irqsave()
 *		- unlink all active send urbs of a vcc that is being closed.
 *
 *  1.3.1:	- added the version number
 *
 *  1.3:	- Added multiple send urb support
 *		- fixed memory leak and vcc->tx_inuse starvation bug
 *		  when not enough memory left in vcc.
 *
 *  1.2:	- Fixed race condition in usbatm_usb_send_data()
 *  1.1:	- Turned off packet debugging
 *
 */

#include "usbatm.h"

#include <asm/uaccess.h>
#include <linux/crc32.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netdevice.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/kthread.h>
#include <linux/ratelimit.h>

#ifdef VERBOSE_DEBUG
static int usbatm_print_packet(const unsigned char *data, int len);
#define PACKETDEBUG(arg...)	usbatm_print_packet(arg)
#define vdbg(arg...)		dbg(arg)
#else
#define PACKETDEBUG(arg...)
#define vdbg(arg...)
#endif

#define DRIVER_AUTHOR	"Johan Verrept, Duncan Sands <duncan.sands@free.fr>"
#define DRIVER_VERSION	"1.10"
#define DRIVER_DESC	"Generic USB ATM/DSL I/O, version " DRIVER_VERSION

static const char usbatm_driver_name[] = "usbatm";

#define UDSL_MAX_RCV_URBS		16
#define UDSL_MAX_SND_URBS		16
#define UDSL_MAX_BUF_SIZE		65536
#define UDSL_DEFAULT_RCV_URBS		4
#define UDSL_DEFAULT_SND_URBS		4
#define UDSL_DEFAULT_RCV_BUF_SIZE	3392	/* 64 * ATM_CELL_SIZE */
#define UDSL_DEFAULT_SND_BUF_SIZE	3392	/* 64 * ATM_CELL_SIZE */

#define ATM_CELL_HEADER			(ATM_CELL_SIZE - ATM_CELL_PAYLOAD)

#define THROTTLE_MSECS			100	/* delay to recover processing after urb submission fails */

static unsigned int num_rcv_urbs = UDSL_DEFAULT_RCV_URBS;
static unsigned int num_snd_urbs = UDSL_DEFAULT_SND_URBS;
static unsigned int rcv_buf_bytes = UDSL_DEFAULT_RCV_BUF_SIZE;
static unsigned int snd_buf_bytes = UDSL_DEFAULT_SND_BUF_SIZE;

module_param(num_rcv_urbs, uint, S_IRUGO);
MODULE_PARM_DESC(num_rcv_urbs,
		 "Number of urbs used for reception (range: 0-"
		 __MODULE_STRING(UDSL_MAX_RCV_URBS) ", default: "
		 __MODULE_STRING(UDSL_DEFAULT_RCV_URBS) ")");

module_param(num_snd_urbs, uint, S_IRUGO);
MODULE_PARM_DESC(num_snd_urbs,
		 "Number of urbs used for transmission (range: 0-"
		 __MODULE_STRING(UDSL_MAX_SND_URBS) ", default: "
		 __MODULE_STRING(UDSL_DEFAULT_SND_URBS) ")");

module_param(rcv_buf_bytes, uint, S_IRUGO);
MODULE_PARM_DESC(rcv_buf_bytes,
		 "Size of the buffers used for reception, in bytes (range: 1-"
		 __MODULE_STRING(UDSL_MAX_BUF_SIZE) ", default: "
		 __MODULE_STRING(UDSL_DEFAULT_RCV_BUF_SIZE) ")");

module_param(snd_buf_bytes, uint, S_IRUGO);
MODULE_PARM_DESC(snd_buf_bytes,
		 "Size of the buffers used for transmission, in bytes (range: 1-"
		 __MODULE_STRING(UDSL_MAX_BUF_SIZE) ", default: "
		 __MODULE_STRING(UDSL_DEFAULT_SND_BUF_SIZE) ")");


/* receive */

struct usbatm_vcc_data {
	/* vpi/vci lookup */
	struct list_head list;
	short vpi;
	int vci;
	struct atm_vcc *vcc;

	/* raw cell reassembly */
	struct sk_buff *sarb;
};


/* send */

struct usbatm_control {
	struct atm_skb_data atm;
	u32 len;
	u32 crc;
};

#define UDSL_SKB(x)		((struct usbatm_control *)(x)->cb)


/* ATM */

static void usbatm_atm_dev_close(struct atm_dev *atm_dev);
static int usbatm_atm_open(struct atm_vcc *vcc);
static void usbatm_atm_close(struct atm_vcc *vcc);
static int usbatm_atm_ioctl(struct atm_dev *atm_dev, unsigned int cmd, void __user * arg);
static int usbatm_atm_send(struct atm_vcc *vcc, struct sk_buff *skb);
static int usbatm_atm_proc_read(struct atm_dev *atm_dev, loff_t * pos, char *page);

static struct atmdev_ops usbatm_atm_devops = {
	.dev_close	= usbatm_atm_dev_close,
	.open		= usbatm_atm_open,
	.close		= usbatm_atm_close,
	.ioctl		= usbatm_atm_ioctl,
	.send		= usbatm_atm_send,
	.proc_read	= usbatm_atm_proc_read,
	.owner		= THIS_MODULE,
};


/***********
**  misc  **
***********/

static inline unsigned int usbatm_pdu_length(unsigned int length)
{
	length += ATM_CELL_PAYLOAD - 1 + ATM_AAL5_TRAILER;
	return length - length % ATM_CELL_PAYLOAD;
}

static inline void usbatm_pop(struct atm_vcc *vcc, struct sk_buff *skb)
{
	if (vcc->pop)
		vcc->pop(vcc, skb);
	else
		dev_kfree_skb_any(skb);
}


/***********
**  urbs  **
************/

static struct urb *usbatm_pop_urb(struct usbatm_channel *channel)
{
	struct urb *urb;

	spin_lock_irq(&channel->lock);
	if (list_empty(&channel->list)) {
		spin_unlock_irq(&channel->lock);
		return NULL;
	}

	urb = list_entry(channel->list.next, struct urb, urb_list);
	list_del(&urb->urb_list);
	spin_unlock_irq(&channel->lock);

	return urb;
}

static int usbatm_submit_urb(struct urb *urb)
{
	struct usbatm_channel *channel = urb->context;
	int ret;

	vdbg("%s: submitting urb 0x%p, size %u",
	     __func__, urb, urb->transfer_buffer_length);

	ret = usb_submit_urb(urb, GFP_ATOMIC);
	if (ret) {
		if (printk_ratelimit())
			atm_warn(channel->usbatm, "%s: urb 0x%p submission failed (%d)!\n",
				__func__, urb, ret);

		/* consider all errors transient and return the buffer back to the queue */
		urb->status = -EAGAIN;
		spin_lock_irq(&channel->lock);

		/* must add to the front when sending; doesn't matter when receiving */
		list_add(&urb->urb_list, &channel->list);

		spin_unlock_irq(&channel->lock);

		/* make sure the channel doesn't stall */
		mod_timer(&channel->delay, jiffies + msecs_to_jiffies(THROTTLE_MSECS));
	}

	return ret;
}

static void usbatm_complete(struct urb *urb)
{
	struct usbatm_channel *channel = urb->context;
	unsigned long flags;
	int status = urb->status;

	vdbg("%s: urb 0x%p, status %d, actual_length %d",
	     __func__, urb, status, urb->actual_length);

	/* usually in_interrupt(), but not always */
	spin_lock_irqsave(&channel->lock, flags);

	/* must add to the back when receiving; doesn't matter when sending */
	list_add_tail(&urb->urb_list, &channel->list);

	spin_unlock_irqrestore(&channel->lock, flags);

	if (unlikely(status) &&
			(!(channel->usbatm->flags & UDSL_IGNORE_EILSEQ) ||
			 status != -EILSEQ)) {
		if (status == -ESHUTDOWN)
			return;

		if (printk_ratelimit())
			atm_warn(channel->usbatm, "%s: urb 0x%p failed (%d)!\n",
				__func__, urb, status);
		/* throttle processing in case of an error */
		mod_timer(&channel->delay, jiffies + msecs_to_jiffies(THROTTLE_MSECS));
	} else
		tasklet_schedule(&channel->tasklet);
}


/*************
**  decode  **
*************/

static inline struct usbatm_vcc_data *usbatm_find_vcc(struct usbatm_data *instance,
						  short vpi, int vci)
{
	struct usbatm_vcc_data *vcc_data;

	list_for_each_entry(vcc_data, &instance->vcc_list, list)
		if ((vcc_data->vci == vci) && (vcc_data->vpi == vpi))
			return vcc_data;
	return NULL;
}

static void usbatm_extract_one_cell(struct usbatm_data *instance, unsigned char *source)
{
	struct atm_vcc *vcc;
	struct sk_buff *sarb;
	short vpi = ((source[0] & 0x0f) << 4)  | (source[1] >> 4);
	int vci = ((source[1] & 0x0f) << 12) | (source[2] << 4) | (source[3] >> 4);
	u8 pti = ((source[3] & 0xe) >> 1);

	vdbg("%s: vpi %hd, vci %d, pti %d", __func__, vpi, vci, pti);

	if ((vci != instance->cached_vci) || (vpi != instance->cached_vpi)) {
		instance->cached_vpi = vpi;
		instance->cached_vci = vci;

		instance->cached_vcc = usbatm_find_vcc(instance, vpi, vci);

		if (!instance->cached_vcc)
			atm_rldbg(instance, "%s: unknown vpi/vci (%hd/%d)!\n", __func__, vpi, vci);
	}

	if (!instance->cached_vcc)
		return;

	vcc = instance->cached_vcc->vcc;

	/* OAM F5 end-to-end */
	if (pti == ATM_PTI_E2EF5) {
		if (printk_ratelimit())
			atm_warn(instance, "%s: OAM not supported (vpi %d, vci %d)!\n",
				__func__, vpi, vci);
		atomic_inc(&vcc->stats->rx_err);
		return;
	}

	sarb = instance->cached_vcc->sarb;

	if (sarb->tail + ATM_CELL_PAYLOAD > sarb->end) {
		atm_rldbg(instance, "%s: buffer overrun (sarb->len %u, vcc: 0x%p)!\n",
				__func__, sarb->len, vcc);
		/* discard cells already received */
		skb_trim(sarb, 0);
		UDSL_ASSERT(instance, sarb->tail + ATM_CELL_PAYLOAD <= sarb->end);
	}

	memcpy(skb_tail_pointer(sarb), source + ATM_CELL_HEADER, ATM_CELL_PAYLOAD);
	__skb_put(sarb, ATM_CELL_PAYLOAD);

	if (pti & 1) {
		struct sk_buff *skb;
		unsigned int length;
		unsigned int pdu_length;

		length = (source[ATM_CELL_SIZE - 6] << 8) + source[ATM_CELL_SIZE - 5];

		/* guard against overflow */
		if (length > ATM_MAX_AAL5_PDU) {
			atm_rldbg(instance, "%s: bogus length %u (vcc: 0x%p)!\n",
				  __func__, length, vcc);
			atomic_inc(&vcc->stats->rx_err);
			goto out;
		}

		pdu_length = usbatm_pdu_length(length);

		if (sarb->len < pdu_length) {
			atm_rldbg(instance, "%s: bogus pdu_length %u (sarb->len: %u, vcc: 0x%p)!\n",
				  __func__, pdu_length, sarb->len, vcc);
			atomic_inc(&vcc->stats->rx_err);
			goto out;
		}

		if (crc32_be(~0, skb_tail_pointer(sarb) - pdu_length, pdu_length) != 0xc704dd7b) {
			atm_rldbg(instance, "%s: packet failed crc check (vcc: 0x%p)!\n",
				  __func__, vcc);
			atomic_inc(&vcc->stats->rx_err);
			goto out;
		}

		vdbg("%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)", __func__, length, pdu_length, vcc);

		if (!(skb = dev_alloc_skb(length))) {
			if (printk_ratelimit())
				atm_err(instance, "%s: no memory for skb (length: %u)!\n",
					__func__, length);
			atomic_inc(&vcc->stats->rx_drop);
			goto out;
		}

		vdbg("%s: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)", __func__, skb, skb->truesize);

		if (!atm_charge(vcc, skb->truesize)) {
			atm_rldbg(instance, "%s: failed atm_charge (skb->truesize: %u)!\n",
				  __func__, skb->truesize);
			dev_kfree_skb_any(skb);
			goto out;	/* atm_charge increments rx_drop */
		}

		skb_copy_to_linear_data(skb,
					skb_tail_pointer(sarb) - pdu_length,
					length);
		__skb_put(skb, length);

		vdbg("%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
		     __func__, skb, skb->len, skb->truesize);

		PACKETDEBUG(skb->data, skb->len);

		vcc->push(vcc, skb);

		atomic_inc(&vcc->stats->rx);
	out:
		skb_trim(sarb, 0);
	}
}

static void usbatm_extract_cells(struct usbatm_data *instance,
		unsigned char *source, unsigned int avail_data)
{
	unsigned int stride = instance->rx_channel.stride;
	unsigned int buf_usage = instance->buf_usage;

	/* extract cells from incoming data, taking into account that
	 * the length of avail data may not be a multiple of stride */

	if (buf_usage > 0) {
		/* we have a partially received atm cell */
		unsigned char *cell_buf = instance->cell_buf;
		unsigned int space_left = stride - buf_usage;

		UDSL_ASSERT(instance, buf_usage <= stride);

		if (avail_data >= space_left) {
			/* add new data and process cell */
			memcpy(cell_buf + buf_usage, source, space_left);
			source += space_left;
			avail_data -= space_left;
			usbatm_extract_one_cell(instance, cell_buf);
			instance->buf_usage = 0;
		} else {
			/* not enough data to fill the cell */
			memcpy(cell_buf + buf_usage, source, avail_data);
			instance->buf_usage = buf_usage + avail_data;
			return;
		}
	}

	for (; avail_data >= stride; avail_data -= stride, source += stride)
		usbatm_extract_one_cell(instance, source);

	if (avail_data > 0) {
		/* length was not a multiple of stride -
		 * save remaining data for next call */
		memcpy(instance->cell_buf, source, avail_data);
		instance->buf_usage = avail_data;
	}
}


/*************
**  encode  **
*************/

static unsigned int usbatm_write_cells(struct usbatm_data *instance,
				       struct sk_buff *skb,
				       u8 *target, unsigned int avail_space)
{
	struct usbatm_control *ctrl = UDSL_SKB(skb);
	struct atm_vcc *vcc = ctrl->atm.vcc;
	unsigned int bytes_written;
	unsigned int stride = instance->tx_channel.stride;

	vdbg("%s: skb->len=%d, avail_space=%u", __func__, skb->len, avail_space);
	UDSL_ASSERT(instance, !(avail_space % stride));

	for (bytes_written = 0; bytes_written < avail_space && ctrl->len;
	     bytes_written += stride, target += stride) {
		unsigned int data_len = min_t(unsigned int, skb->len, ATM_CELL_PAYLOAD);
		unsigned int left = ATM_CELL_PAYLOAD - data_len;
		u8 *ptr = target;

		ptr[0] = vcc->vpi >> 4;
		ptr[1] = (vcc->vpi << 4) | (vcc->vci >> 12);
		ptr[2] = vcc->vci >> 4;
		ptr[3] = vcc->vci << 4;
		ptr[4] = 0xec;
		ptr += ATM_CELL_HEADER;

		skb_copy_from_linear_data(skb, ptr, data_len);
		ptr += data_len;
		__skb_pull(skb, data_len);

		if (!left)
			continue;

		memset(ptr, 0, left);

		if (left >= ATM_AAL5_TRAILER) {	/* trailer will go in this cell */
			u8 *trailer = target + ATM_CELL_SIZE - ATM_AAL5_TRAILER;
			/* trailer[0] = 0;		UU = 0 */
			/* trailer[1] = 0;		CPI = 0 */
			trailer[2] = ctrl->len >> 8;
			trailer[3] = ctrl->len;

			ctrl->crc = ~crc32_be(ctrl->crc, ptr, left - 4);

			trailer[4] = ctrl->crc >> 24;
			trailer[5] = ctrl->crc >> 16;
			trailer[6] = ctrl->crc >> 8;
			trailer[7] = ctrl->crc;

			target[3] |= 0x2;	/* adjust PTI */

			ctrl->len = 0;		/* tag this skb finished */
		} else
			ctrl->crc = crc32_be(ctrl->crc, ptr, left);
	}

	return bytes_written;
}


/**************
**  receive  **
**************/

static void usbatm_rx_process(unsigned long data)
{
	struct usbatm_data *instance = (struct usbatm_data *)data;
	struct urb *urb;

	while ((urb = usbatm_pop_urb(&instance->rx_channel))) {
		vdbg("%s: processing urb 0x%p", __func__, urb);

		if (usb_pipeisoc(urb->pipe)) {
			unsigned char *merge_start = NULL;
			unsigned int merge_length = 0;
			const unsigned int packet_size = instance->rx_channel.packet_size;
			int i;

			for (i = 0; i < urb->number_of_packets; i++) {
				if (!urb->iso_frame_desc[i].status) {
					unsigned int actual_length = urb->iso_frame_desc[i].actual_length;

					UDSL_ASSERT(instance, actual_length <= packet_size);

					if (!merge_length)
						merge_start = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
					merge_length += actual_length;
					if (merge_length && (actual_length < packet_size)) {
						usbatm_extract_cells(instance, merge_start, merge_length);
						merge_length = 0;
					}
				} else {
					atm_rldbg(instance, "%s: status %d in frame %d!\n", __func__, urb->status, i);
					if (merge_length)
						usbatm_extract_cells(instance, merge_start, merge_length);
					merge_length = 0;
					instance->buf_usage = 0;
				}
			}

			if (merge_length)
				usbatm_extract_cells(instance, merge_start, merge_length);
		} else
			if (!urb->status)
				usbatm_extract_cells(instance, urb->transfer_buffer, urb->actual_length);
			else
				instance->buf_usage = 0;

		if (usbatm_submit_urb(urb))
			return;
	}
}


/***********
**  send  **
***********/

static void usbatm_tx_process(unsigned long data)
{
	struct usbatm_data *instance = (struct usbatm_data *)data;
	struct sk_buff *skb = instance->current_skb;
	struct urb *urb = NULL;
	const unsigned int buf_size = instance->tx_channel.buf_size;
	unsigned int bytes_written = 0;
	u8 *buffer = NULL;

	if (!skb)
		skb = skb_dequeue(&instance->sndqueue);

	while (skb) {
		if (!urb) {
			urb = usbatm_pop_urb(&instance->tx_channel);
			if (!urb)
				break;		/* no more senders */
			buffer = urb->transfer_buffer;
			bytes_written = (urb->status == -EAGAIN) ?
				urb->transfer_buffer_length : 0;
		}

		bytes_written += usbatm_write_cells(instance, skb,
						  buffer + bytes_written,
						  buf_size - bytes_written);

		vdbg("%s: wrote %u bytes from skb 0x%p to urb 0x%p",
		     __func__, bytes_written, skb, urb);

		if (!UDSL_SKB(skb)->len) {
			struct atm_vcc *vcc = UDSL_SKB(skb)->atm.vcc;

			usbatm_pop(vcc, skb);
			atomic_inc(&vcc->stats->tx);

			skb = skb_dequeue(&instance->sndqueue);
		}

		if (bytes_written == buf_size || (!skb && bytes_written)) {
			urb->transfer_buffer_length = bytes_written;

			if (usbatm_submit_urb(urb))
				break;
			urb = NULL;
		}
	}

	instance->current_skb = skb;
}

static void usbatm_cancel_send(struct usbatm_data *instance,
			       struct atm_vcc *vcc)
{
	struct sk_buff *skb, *n;

	atm_dbg(instance, "%s entered\n", __func__);
	spin_lock_irq(&instance->sndqueue.lock);
	skb_queue_walk_safe(&instance->sndqueue, skb, n) {
		if (UDSL_SKB(skb)->atm.vcc == vcc) {
			atm_dbg(instance, "%s: popping skb 0x%p\n", __func__, skb);
			__skb_unlink(skb, &instance->sndqueue);
			usbatm_pop(vcc, skb);
		}
	}
	spin_unlock_irq(&instance->sndqueue.lock);

	tasklet_disable(&instance->tx_channel.tasklet);
	if ((skb = instance->current_skb) && (UDSL_SKB(skb)->atm.vcc == vcc)) {
		atm_dbg(instance, "%s: popping current skb (0x%p)\n", __func__, skb);
		instance->current_skb = NULL;
		usbatm_pop(vcc, skb);
	}
	tasklet_enable(&instance->tx_channel.tasklet);
	atm_dbg(instance, "%s done\n", __func__);
}

static int usbatm_atm_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
	struct usbatm_data *instance = vcc->dev->dev_data;
	struct usbatm_control *ctrl = UDSL_SKB(skb);
	int err;

	vdbg("%s called (skb 0x%p, len %u)", __func__, skb, skb->len);

	/* racy disconnection check - fine */
	if (!instance || instance->disconnected) {
#ifdef DEBUG
		printk_ratelimited(KERN_DEBUG "%s: %s!\n", __func__, instance ? "disconnected" : "NULL instance");
#endif
		err = -ENODEV;
		goto fail;
	}

	if (vcc->qos.aal != ATM_AAL5) {
		atm_rldbg(instance, "%s: unsupported ATM type %d!\n", __func__, vcc->qos.aal);
		err = -EINVAL;
		goto fail;
	}

	if (skb->len > ATM_MAX_AAL5_PDU) {
		atm_rldbg(instance, "%s: packet too long (%d vs %d)!\n",
				__func__, skb->len, ATM_MAX_AAL5_PDU);
		err = -EINVAL;
		goto fail;
	}

	PACKETDEBUG(skb->data, skb->len);

	/* initialize the control block */
	ctrl->atm.vcc = vcc;
	ctrl->len = skb->len;
	ctrl->crc = crc32_be(~0, skb->data, skb->len);

	skb_queue_tail(&instance->sndqueue, skb);
	tasklet_schedule(&instance->tx_channel.tasklet);

	return 0;

 fail:
	usbatm_pop(vcc, skb);
	return err;
}


/********************
**  bean counting  **
********************/

static void usbatm_destroy_instance(struct kref *kref)
{
	struct usbatm_data *instance = container_of(kref, struct usbatm_data, refcount);

	dbg("%s", __func__);

	tasklet_kill(&instance->rx_channel.tasklet);
	tasklet_kill(&instance->tx_channel.tasklet);
	usb_put_dev(instance->usb_dev);
	kfree(instance);
}

static void usbatm_get_instance(struct usbatm_data *instance)
{
	dbg("%s", __func__);

	kref_get(&instance->refcount);
}

static void usbatm_put_instance(struct usbatm_data *instance)
{
	dbg("%s", __func__);

	kref_put(&instance->refcount, usbatm_destroy_instance);
}


/**********
**  ATM  **
**********/

static void usbatm_atm_dev_close(struct atm_dev *atm_dev)
{
	struct usbatm_data *instance = atm_dev->dev_data;

	dbg("%s", __func__);

	if (!instance)
		return;

	atm_dev->dev_data = NULL; /* catch bugs */
	usbatm_put_instance(instance);	/* taken in usbatm_atm_init */
}

static int usbatm_atm_proc_read(struct atm_dev *atm_dev, loff_t * pos, char *page)
{
	struct usbatm_data *instance = atm_dev->dev_data;
	int left = *pos;

	if (!instance) {
		dbg("%s: NULL instance!", __func__);
		return -ENODEV;
	}

	if (!left--)
		return sprintf(page, "%s\n", instance->description);

	if (!left--)
		return sprintf(page, "MAC: %pM\n", atm_dev->esi);

	if (!left--)
		return sprintf(page,
			       "AAL5: tx %d ( %d err ), rx %d ( %d err, %d drop )\n",
			       atomic_read(&atm_dev->stats.aal5.tx),
			       atomic_read(&atm_dev->stats.aal5.tx_err),
			       atomic_read(&atm_dev->stats.aal5.rx),
			       atomic_read(&atm_dev->stats.aal5.rx_err),
			       atomic_read(&atm_dev->stats.aal5.rx_drop));

	if (!left--) {
		if (instance->disconnected)
			return sprintf(page, "Disconnected\n");
		else
			switch (atm_dev->signal) {
			case ATM_PHY_SIG_FOUND:
				return sprintf(page, "Line up\n");
			case ATM_PHY_SIG_LOST:
				return sprintf(page, "Line down\n");
			default:
				return sprintf(page, "Line state unknown\n");
			}
	}

	return 0;
}

static int usbatm_atm_open(struct atm_vcc *vcc)
{
	struct usbatm_data *instance = vcc->dev->dev_data;
	struct usbatm_vcc_data *new = NULL;
	int ret;
	int vci = vcc->vci;
	short vpi = vcc->vpi;

	if (!instance) {
		dbg("%s: NULL data!", __func__);
		return -ENODEV;
	}

	atm_dbg(instance, "%s: vpi %hd, vci %d\n", __func__, vpi, vci);

	/* only support AAL5 */
	if ((vcc->qos.aal != ATM_AAL5)) {
		atm_warn(instance, "%s: unsupported ATM type %d!\n", __func__, vcc->qos.aal);
		return -EINVAL;
	}

	/* sanity checks */
	if ((vcc->qos.rxtp.max_sdu < 0) || (vcc->qos.rxtp.max_sdu > ATM_MAX_AAL5_PDU)) {
		atm_dbg(instance, "%s: max_sdu %d out of range!\n", __func__, vcc->qos.rxtp.max_sdu);
		return -EINVAL;
	}

	mutex_lock(&instance->serialize);	/* vs self, usbatm_atm_close, usbatm_usb_disconnect */

	if (instance->disconnected) {
		atm_dbg(instance, "%s: disconnected!\n", __func__);
		ret = -ENODEV;
		goto fail;
	}

	if (usbatm_find_vcc(instance, vpi, vci)) {
		atm_dbg(instance, "%s: %hd/%d already in use!\n", __func__, vpi, vci);
		ret = -EADDRINUSE;
		goto fail;
	}

	if (!(new = kzalloc(sizeof(struct usbatm_vcc_data), GFP_KERNEL))) {
		atm_err(instance, "%s: no memory for vcc_data!\n", __func__);
		ret = -ENOMEM;
		goto fail;
	}

	new->vcc = vcc;
	new->vpi = vpi;
	new->vci = vci;

	new->sarb = alloc_skb(usbatm_pdu_length(vcc->qos.rxtp.max_sdu), GFP_KERNEL);
	if (!new->sarb) {
		atm_err(instance, "%s: no memory for SAR buffer!\n", __func__);
		ret = -ENOMEM;
		goto fail;
	}

	vcc->dev_data = new;

	tasklet_disable(&instance->rx_channel.tasklet);
	instance->cached_vcc = new;
	instance->cached_vpi = vpi;
	instance->cached_vci = vci;
	list_add(&new->list, &instance->vcc_list);
	tasklet_enable(&instance->rx_channel.tasklet);

	set_bit(ATM_VF_ADDR, &vcc->flags);
	set_bit(ATM_VF_PARTIAL, &vcc->flags);
	set_bit(ATM_VF_READY, &vcc->flags);

	mutex_unlock(&instance->serialize);

	atm_dbg(instance, "%s: allocated vcc data 0x%p\n", __func__, new);

	return 0;

fail:
	kfree(new);
	mutex_unlock(&instance->serialize);
	return ret;
}

static void usbatm_atm_close(struct atm_vcc *vcc)
{
	struct usbatm_data *instance = vcc->dev->dev_data;
	struct usbatm_vcc_data *vcc_data = vcc->dev_data;

	if (!instance || !vcc_data) {
		dbg("%s: NULL data!", __func__);
		return;
	}

	atm_dbg(instance, "%s entered\n", __func__);

	atm_dbg(instance, "%s: deallocating vcc 0x%p with vpi %d vci %d\n",
		__func__, vcc_data, vcc_data->vpi, vcc_data->vci);

	usbatm_cancel_send(instance, vcc);

	mutex_lock(&instance->serialize);	/* vs self, usbatm_atm_open, usbatm_usb_disconnect */

	tasklet_disable(&instance->rx_channel.tasklet);
	if (instance->cached_vcc == vcc_data) {
		instance->cached_vcc = NULL;
		instance->cached_vpi = ATM_VPI_UNSPEC;
		instance->cached_vci = ATM_VCI_UNSPEC;
	}
	list_del(&vcc_data->list);
	tasklet_enable(&instance->rx_channel.tasklet);

	kfree_skb(vcc_data->sarb);
	vcc_data->sarb = NULL;

	kfree(vcc_data);
	vcc->dev_data = NULL;

	vcc->vpi = ATM_VPI_UNSPEC;
	vcc->vci = ATM_VCI_UNSPEC;
	clear_bit(ATM_VF_READY, &vcc->flags);
	clear_bit(ATM_VF_PARTIAL, &vcc->flags);
	clear_bit(ATM_VF_ADDR, &vcc->flags);

	mutex_unlock(&instance->serialize);

	atm_dbg(instance, "%s successful\n", __func__);
}

static int usbatm_atm_ioctl(struct atm_dev *atm_dev, unsigned int cmd,
			  void __user * arg)
{
	struct usbatm_data *instance = atm_dev->dev_data;

	if (!instance || instance->disconnected) {
		dbg("%s: %s!", __func__, instance ? "disconnected" : "NULL instance");
		return -ENODEV;
	}

	switch (cmd) {
	case ATM_QUERYLOOP:
		return put_user(ATM_LM_NONE, (int __user *)arg) ? -EFAULT : 0;
	default:
		return -ENOIOCTLCMD;
	}
}

static int usbatm_atm_init(struct usbatm_data *instance)
{
	struct atm_dev *atm_dev;
	int ret, i;

	/* ATM init.  The ATM initialization scheme suffers from an intrinsic race
	 * condition: callbacks we register can be executed at once, before we have
	 * initialized the struct atm_dev.  To protect against this, all callbacks
	 * abort if atm_dev->dev_data is NULL. */
	atm_dev = atm_dev_register(instance->driver_name,
				   &instance->usb_intf->dev, &usbatm_atm_devops,
				   -1, NULL);
	if (!atm_dev) {
		usb_err(instance, "%s: failed to register ATM device!\n", __func__);
		return -1;
	}

	instance->atm_dev = atm_dev;

	atm_dev->ci_range.vpi_bits = ATM_CI_MAX;
	atm_dev->ci_range.vci_bits = ATM_CI_MAX;
	atm_dev->signal = ATM_PHY_SIG_UNKNOWN;

	/* temp init ATM device, set to 128kbit */
	atm_dev->link_rate = 128 * 1000 / 424;

	if (instance->driver->atm_start && ((ret = instance->driver->atm_start(instance, atm_dev)) < 0)) {
		atm_err(instance, "%s: atm_start failed: %d!\n", __func__, ret);
		goto fail;
	}

	usbatm_get_instance(instance);	/* dropped in usbatm_atm_dev_close */

	/* ready for ATM callbacks */
	mb();
	atm_dev->dev_data = instance;

	/* submit all rx URBs */
	for (i = 0; i < num_rcv_urbs; i++)
		usbatm_submit_urb(instance->urbs[i]);

	return 0;

 fail:
	instance->atm_dev = NULL;
	atm_dev_deregister(atm_dev); /* usbatm_atm_dev_close will eventually be called */
	return ret;
}


/**********
**  USB  **
**********/

static int usbatm_do_heavy_init(void *arg)
{
	struct usbatm_data *instance = arg;
	int ret;

	allow_signal(SIGTERM);
	complete(&instance->thread_started);

	ret = instance->driver->heavy_init(instance, instance->usb_intf);

	if (!ret)
		ret = usbatm_atm_init(instance);

	mutex_lock(&instance->serialize);
	instance->thread = NULL;
	mutex_unlock(&instance->serialize);

	complete_and_exit(&instance->thread_exited, ret);
}

static int usbatm_heavy_init(struct usbatm_data *instance)
{
	struct task_struct *t;

	t = kthread_create(usbatm_do_heavy_init, instance,
			instance->driver->driver_name);
	if (IS_ERR(t)) {
		usb_err(instance, "%s: failed to create kernel_thread (%ld)!\n",
				__func__, PTR_ERR(t));
		return PTR_ERR(t);
	}

	instance->thread = t;
	wake_up_process(t);
	wait_for_completion(&instance->thread_started);

	return 0;
}

static void usbatm_tasklet_schedule(unsigned long data)
{
	tasklet_schedule((struct tasklet_struct *) data);
}

static void usbatm_init_channel(struct usbatm_channel *channel)
{
	spin_lock_init(&channel->lock);
	INIT_LIST_HEAD(&channel->list);
	channel->delay.function = usbatm_tasklet_schedule;
	channel->delay.data = (unsigned long) &channel->tasklet;
	init_timer(&channel->delay);
}

int usbatm_usb_probe(struct usb_interface *intf, const struct usb_device_id *id,
		     struct usbatm_driver *driver)
{
	struct device *dev = &intf->dev;
	struct usb_device *usb_dev = interface_to_usbdev(intf);
	struct usbatm_data *instance;
	char *buf;
	int error = -ENOMEM;
	int i, length;
	unsigned int maxpacket, num_packets;

	dev_dbg(dev, "%s: trying driver %s with vendor=%04x, product=%04x, ifnum %2d\n",
			__func__, driver->driver_name,
			le16_to_cpu(usb_dev->descriptor.idVendor),
			le16_to_cpu(usb_dev->descriptor.idProduct),
			intf->altsetting->desc.bInterfaceNumber);

	/* instance init */
	instance = kzalloc(sizeof(*instance) + sizeof(struct urb *) * (num_rcv_urbs + num_snd_urbs), GFP_KERNEL);
	if (!instance) {
		dev_err(dev, "%s: no memory for instance data!\n", __func__);
		return -ENOMEM;
	}

	/* public fields */

	instance->driver = driver;
	snprintf(instance->driver_name, sizeof(instance->driver_name), driver->driver_name);

	instance->usb_dev = usb_dev;
	instance->usb_intf = intf;

	buf = instance->description;
	length = sizeof(instance->description);

	if ((i = usb_string(usb_dev, usb_dev->descriptor.iProduct, buf, length)) < 0)
		goto bind;

	buf += i;
	length -= i;

	i = scnprintf(buf, length, " (");
	buf += i;
	length -= i;

	if (length <= 0 || (i = usb_make_path(usb_dev, buf, length)) < 0)
		goto bind;

	buf += i;
	length -= i;

	snprintf(buf, length, ")");

 bind:
	if (driver->bind && (error = driver->bind(instance, intf, id)) < 0) {
			dev_err(dev, "%s: bind failed: %d!\n", __func__, error);
			goto fail_free;
	}

	/* private fields */

	kref_init(&instance->refcount);		/* dropped in usbatm_usb_disconnect */
	mutex_init(&instance->serialize);

	instance->thread = NULL;
	init_completion(&instance->thread_started);
	init_completion(&instance->thread_exited);

	INIT_LIST_HEAD(&instance->vcc_list);
	skb_queue_head_init(&instance->sndqueue);

	usbatm_init_channel(&instance->rx_channel);
	usbatm_init_channel(&instance->tx_channel);
	tasklet_init(&instance->rx_channel.tasklet, usbatm_rx_process, (unsigned long)instance);
	tasklet_init(&instance->tx_channel.tasklet, usbatm_tx_process, (unsigned long)instance);
	instance->rx_channel.stride = ATM_CELL_SIZE + driver->rx_padding;
	instance->tx_channel.stride = ATM_CELL_SIZE + driver->tx_padding;
	instance->rx_channel.usbatm = instance->tx_channel.usbatm = instance;

	if ((instance->flags & UDSL_USE_ISOC) && driver->isoc_in)
		instance->rx_channel.endpoint = usb_rcvisocpipe(usb_dev, driver->isoc_in);
	else
		instance->rx_channel.endpoint = usb_rcvbulkpipe(usb_dev, driver->bulk_in);

	instance->tx_channel.endpoint = usb_sndbulkpipe(usb_dev, driver->bulk_out);

	/* tx buffer size must be a positive multiple of the stride */
	instance->tx_channel.buf_size = max(instance->tx_channel.stride,
			snd_buf_bytes - (snd_buf_bytes % instance->tx_channel.stride));

	/* rx buffer size must be a positive multiple of the endpoint maxpacket */
	maxpacket = usb_maxpacket(usb_dev, instance->rx_channel.endpoint, 0);

	if ((maxpacket < 1) || (maxpacket > UDSL_MAX_BUF_SIZE)) {
		dev_err(dev, "%s: invalid endpoint %02x!\n", __func__,
				usb_pipeendpoint(instance->rx_channel.endpoint));
		error = -EINVAL;
		goto fail_unbind;
	}

	num_packets = max(1U, (rcv_buf_bytes + maxpacket / 2) / maxpacket); /* round */

	if (num_packets * maxpacket > UDSL_MAX_BUF_SIZE)
		num_packets--;

	instance->rx_channel.buf_size = num_packets * maxpacket;
	instance->rx_channel.packet_size = maxpacket;

#ifdef DEBUG
	for (i = 0; i < 2; i++) {
		struct usbatm_channel *channel = i ?
			&instance->tx_channel : &instance->rx_channel;

		dev_dbg(dev, "%s: using %d byte buffer for %s channel 0x%p\n", __func__, channel->buf_size, i ? "tx" : "rx", channel);
	}
#endif

	/* initialize urbs */

	for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
		u8 *buffer;
		struct usbatm_channel *channel = i < num_rcv_urbs ?
			&instance->rx_channel : &instance->tx_channel;
		struct urb *urb;
		unsigned int iso_packets = usb_pipeisoc(channel->endpoint) ? channel->buf_size / channel->packet_size : 0;

		UDSL_ASSERT(instance, !usb_pipeisoc(channel->endpoint) || usb_pipein(channel->endpoint));

		urb = usb_alloc_urb(iso_packets, GFP_KERNEL);
		if (!urb) {
			dev_err(dev, "%s: no memory for urb %d!\n", __func__, i);
			error = -ENOMEM;
			goto fail_unbind;
		}

		instance->urbs[i] = urb;

		/* zero the tx padding to avoid leaking information */
		buffer = kzalloc(channel->buf_size, GFP_KERNEL);
		if (!buffer) {
			dev_err(dev, "%s: no memory for buffer %d!\n", __func__, i);
			error = -ENOMEM;
			goto fail_unbind;
		}

		usb_fill_bulk_urb(urb, instance->usb_dev, channel->endpoint,
				  buffer, channel->buf_size, usbatm_complete, channel);
		if (iso_packets) {
			int j;
			urb->interval = 1;
			urb->transfer_flags = URB_ISO_ASAP;
			urb->number_of_packets = iso_packets;
			for (j = 0; j < iso_packets; j++) {
				urb->iso_frame_desc[j].offset = channel->packet_size * j;
				urb->iso_frame_desc[j].length = channel->packet_size;
			}
		}

		/* put all tx URBs on the list of spares */
		if (i >= num_rcv_urbs)
			list_add_tail(&urb->urb_list, &channel->list);

		vdbg("%s: alloced buffer 0x%p buf size %u urb 0x%p",
		     __func__, urb->transfer_buffer, urb->transfer_buffer_length, urb);
	}

	instance->cached_vpi = ATM_VPI_UNSPEC;
	instance->cached_vci = ATM_VCI_UNSPEC;
	instance->cell_buf = kmalloc(instance->rx_channel.stride, GFP_KERNEL);

	if (!instance->cell_buf) {
		dev_err(dev, "%s: no memory for cell buffer!\n", __func__);
		error = -ENOMEM;
		goto fail_unbind;
	}

	if (!(instance->flags & UDSL_SKIP_HEAVY_INIT) && driver->heavy_init) {
		error = usbatm_heavy_init(instance);
	} else {
		complete(&instance->thread_exited);	/* pretend that heavy_init was run */
		error = usbatm_atm_init(instance);
	}

	if (error < 0)
		goto fail_unbind;

	usb_get_dev(usb_dev);
	usb_set_intfdata(intf, instance);

	return 0;

 fail_unbind:
	if (instance->driver->unbind)
		instance->driver->unbind(instance, intf);
 fail_free:
	kfree(instance->cell_buf);

	for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
		if (instance->urbs[i])
			kfree(instance->urbs[i]->transfer_buffer);
		usb_free_urb(instance->urbs[i]);
	}

	kfree(instance);

	return error;
}
EXPORT_SYMBOL_GPL(usbatm_usb_probe);

void usbatm_usb_disconnect(struct usb_interface *intf)
{
	struct device *dev = &intf->dev;
	struct usbatm_data *instance = usb_get_intfdata(intf);
	struct usbatm_vcc_data *vcc_data;
	int i;

	dev_dbg(dev, "%s entered\n", __func__);

	if (!instance) {
		dev_dbg(dev, "%s: NULL instance!\n", __func__);
		return;
	}

	usb_set_intfdata(intf, NULL);

	mutex_lock(&instance->serialize);
	instance->disconnected = 1;
	if (instance->thread != NULL)
		send_sig(SIGTERM, instance->thread, 1);
	mutex_unlock(&instance->serialize);

	wait_for_completion(&instance->thread_exited);

	mutex_lock(&instance->serialize);
	list_for_each_entry(vcc_data, &instance->vcc_list, list)
		vcc_release_async(vcc_data->vcc, -EPIPE);
	mutex_unlock(&instance->serialize);

	tasklet_disable(&instance->rx_channel.tasklet);
	tasklet_disable(&instance->tx_channel.tasklet);

	for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++)
		usb_kill_urb(instance->urbs[i]);

	del_timer_sync(&instance->rx_channel.delay);
	del_timer_sync(&instance->tx_channel.delay);

	/* turn usbatm_[rt]x_process into something close to a no-op */
	/* no need to take the spinlock */
	INIT_LIST_HEAD(&instance->rx_channel.list);
	INIT_LIST_HEAD(&instance->tx_channel.list);

	tasklet_enable(&instance->rx_channel.tasklet);
	tasklet_enable(&instance->tx_channel.tasklet);

	if (instance->atm_dev && instance->driver->atm_stop)
		instance->driver->atm_stop(instance, instance->atm_dev);

	if (instance->driver->unbind)
		instance->driver->unbind(instance, intf);

	instance->driver_data = NULL;

	for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
		kfree(instance->urbs[i]->transfer_buffer);
		usb_free_urb(instance->urbs[i]);
	}

	kfree(instance->cell_buf);

	/* ATM finalize */
	if (instance->atm_dev) {
		atm_dev_deregister(instance->atm_dev);
		instance->atm_dev = NULL;
	}

	usbatm_put_instance(instance);	/* taken in usbatm_usb_probe */
}
EXPORT_SYMBOL_GPL(usbatm_usb_disconnect);


/***********
**  init  **
***********/

static int __init usbatm_usb_init(void)
{
	dbg("%s: driver version %s", __func__, DRIVER_VERSION);

	if (sizeof(struct usbatm_control) > FIELD_SIZEOF(struct sk_buff, cb)) {
		printk(KERN_ERR "%s unusable with this kernel!\n", usbatm_driver_name);
		return -EIO;
	}

	if ((num_rcv_urbs > UDSL_MAX_RCV_URBS)
	    || (num_snd_urbs > UDSL_MAX_SND_URBS)
	    || (rcv_buf_bytes < 1)
	    || (rcv_buf_bytes > UDSL_MAX_BUF_SIZE)
	    || (snd_buf_bytes < 1)
	    || (snd_buf_bytes > UDSL_MAX_BUF_SIZE))
		return -EINVAL;

	return 0;
}
module_init(usbatm_usb_init);

static void __exit usbatm_usb_exit(void)
{
	dbg("%s", __func__);
}
module_exit(usbatm_usb_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_VERSION(DRIVER_VERSION);

/************
**  debug  **
************/

#ifdef VERBOSE_DEBUG
static int usbatm_print_packet(const unsigned char *data, int len)
{
	unsigned char buffer[256];
	int i = 0, j = 0;

	for (i = 0; i < len;) {
		buffer[0] = '\0';
		sprintf(buffer, "%.3d :", i);
		for (j = 0; (j < 16) && (i < len); j++, i++)
			sprintf(buffer, "%s %2.2x", buffer, data[i]);
		dbg("%s", buffer);
	}
	return i;
}
#endif