summaryrefslogtreecommitdiffstats
path: root/drivers/net/can/usb/usb_8dev.c
blob: de95b1ccba3e3b6d4d00e313acb280cd178a000d (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
/*
 * CAN driver for "8 devices" USB2CAN converter
 *
 * Copyright (C) 2012 Bernd Krumboeck (krumboeck@universalnet.at)
 *
 * 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; version 2 of the License.
 *
 * 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.
 *
 * This driver is inspired by the 3.2.0 version of drivers/net/can/usb/ems_usb.c
 * and drivers/net/can/usb/esd_usb2.c
 *
 * Many thanks to Gerhard Bertelsmann (info@gerhard-bertelsmann.de)
 * for testing and fixing this driver. Also many thanks to "8 devices",
 * who were very cooperative and answered my questions.
 */

#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/usb.h>

#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <linux/can/led.h>

/* driver constants */
#define MAX_RX_URBS			20
#define MAX_TX_URBS			20
#define RX_BUFFER_SIZE			64

/* vendor and product id */
#define USB_8DEV_VENDOR_ID		0x0483
#define USB_8DEV_PRODUCT_ID		0x1234

/* endpoints */
enum usb_8dev_endpoint {
	USB_8DEV_ENDP_DATA_RX = 1,
	USB_8DEV_ENDP_DATA_TX,
	USB_8DEV_ENDP_CMD_RX,
	USB_8DEV_ENDP_CMD_TX
};

/* device CAN clock */
#define USB_8DEV_ABP_CLOCK		32000000

/* setup flags */
#define USB_8DEV_SILENT			0x01
#define USB_8DEV_LOOPBACK		0x02
#define USB_8DEV_DISABLE_AUTO_RESTRANS	0x04
#define USB_8DEV_STATUS_FRAME		0x08

/* commands */
enum usb_8dev_cmd {
	USB_8DEV_RESET = 1,
	USB_8DEV_OPEN,
	USB_8DEV_CLOSE,
	USB_8DEV_SET_SPEED,
	USB_8DEV_SET_MASK_FILTER,
	USB_8DEV_GET_STATUS,
	USB_8DEV_GET_STATISTICS,
	USB_8DEV_GET_SERIAL,
	USB_8DEV_GET_SOFTW_VER,
	USB_8DEV_GET_HARDW_VER,
	USB_8DEV_RESET_TIMESTAMP,
	USB_8DEV_GET_SOFTW_HARDW_VER
};

/* command options */
#define USB_8DEV_BAUD_MANUAL		0x09
#define USB_8DEV_CMD_START		0x11
#define USB_8DEV_CMD_END		0x22

#define USB_8DEV_CMD_SUCCESS		0
#define USB_8DEV_CMD_ERROR		255

#define USB_8DEV_CMD_TIMEOUT		1000

/* frames */
#define USB_8DEV_DATA_START		0x55
#define USB_8DEV_DATA_END		0xAA

#define USB_8DEV_TYPE_CAN_FRAME		0
#define USB_8DEV_TYPE_ERROR_FRAME	3

#define USB_8DEV_EXTID			0x01
#define USB_8DEV_RTR			0x02
#define USB_8DEV_ERR_FLAG		0x04

/* status */
#define USB_8DEV_STATUSMSG_OK		0x00  /* Normal condition. */
#define USB_8DEV_STATUSMSG_OVERRUN	0x01  /* Overrun occured when sending */
#define USB_8DEV_STATUSMSG_BUSLIGHT	0x02  /* Error counter has reached 96 */
#define USB_8DEV_STATUSMSG_BUSHEAVY	0x03  /* Error count. has reached 128 */
#define USB_8DEV_STATUSMSG_BUSOFF	0x04  /* Device is in BUSOFF */
#define USB_8DEV_STATUSMSG_STUFF	0x20  /* Stuff Error */
#define USB_8DEV_STATUSMSG_FORM		0x21  /* Form Error */
#define USB_8DEV_STATUSMSG_ACK		0x23  /* Ack Error */
#define USB_8DEV_STATUSMSG_BIT0		0x24  /* Bit1 Error */
#define USB_8DEV_STATUSMSG_BIT1		0x25  /* Bit0 Error */
#define USB_8DEV_STATUSMSG_CRC		0x27  /* CRC Error */

#define USB_8DEV_RP_MASK		0x7F  /* Mask for Receive Error Bit */


/* table of devices that work with this driver */
static const struct usb_device_id usb_8dev_table[] = {
	{ USB_DEVICE(USB_8DEV_VENDOR_ID, USB_8DEV_PRODUCT_ID) },
	{ }					/* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_8dev_table);

struct usb_8dev_tx_urb_context {
	struct usb_8dev_priv *priv;

	u32 echo_index;
	u8 dlc;
};

/* Structure to hold all of our device specific stuff */
struct usb_8dev_priv {
	struct can_priv can; /* must be the first member */

	struct sk_buff *echo_skb[MAX_TX_URBS];

	struct usb_device *udev;
	struct net_device *netdev;

	atomic_t active_tx_urbs;
	struct usb_anchor tx_submitted;
	struct usb_8dev_tx_urb_context tx_contexts[MAX_TX_URBS];

	struct usb_anchor rx_submitted;

	struct can_berr_counter bec;

	u8 *cmd_msg_buffer;

	struct mutex usb_8dev_cmd_lock;

};

/* tx frame */
struct __packed usb_8dev_tx_msg {
	u8 begin;
	u8 flags;	/* RTR and EXT_ID flag */
	__be32 id;	/* upper 3 bits not used */
	u8 dlc;		/* data length code 0-8 bytes */
	u8 data[8];	/* 64-bit data */
	u8 end;
};

/* rx frame */
struct __packed usb_8dev_rx_msg {
	u8 begin;
	u8 type;		/* frame type */
	u8 flags;		/* RTR and EXT_ID flag */
	__be32 id;		/* upper 3 bits not used */
	u8 dlc;			/* data length code 0-8 bytes */
	u8 data[8];		/* 64-bit data */
	__be32 timestamp;	/* 32-bit timestamp */
	u8 end;
};

/* command frame */
struct __packed usb_8dev_cmd_msg {
	u8 begin;
	u8 channel;	/* unkown - always 0 */
	u8 command;	/* command to execute */
	u8 opt1;	/* optional parameter / return value */
	u8 opt2;	/* optional parameter 2 */
	u8 data[10];	/* optional parameter and data */
	u8 end;
};

static int usb_8dev_send_cmd_msg(struct usb_8dev_priv *priv, u8 *msg, int size)
{
	int actual_length;

	return usb_bulk_msg(priv->udev,
			    usb_sndbulkpipe(priv->udev, USB_8DEV_ENDP_CMD_TX),
			    msg, size, &actual_length, USB_8DEV_CMD_TIMEOUT);
}

static int usb_8dev_wait_cmd_msg(struct usb_8dev_priv *priv, u8 *msg, int size,
				int *actual_length)
{
	return usb_bulk_msg(priv->udev,
			    usb_rcvbulkpipe(priv->udev, USB_8DEV_ENDP_CMD_RX),
			    msg, size, actual_length, USB_8DEV_CMD_TIMEOUT);
}

/* Send command to device and receive result.
 * Command was successful when opt1 = 0.
 */
static int usb_8dev_send_cmd(struct usb_8dev_priv *priv,
			     struct usb_8dev_cmd_msg *out,
			     struct usb_8dev_cmd_msg *in)
{
	int err;
	int num_bytes_read;
	struct net_device *netdev;

	netdev = priv->netdev;

	out->begin = USB_8DEV_CMD_START;
	out->end = USB_8DEV_CMD_END;

	mutex_lock(&priv->usb_8dev_cmd_lock);

	memcpy(priv->cmd_msg_buffer, out,
		sizeof(struct usb_8dev_cmd_msg));

	err = usb_8dev_send_cmd_msg(priv, priv->cmd_msg_buffer,
				    sizeof(struct usb_8dev_cmd_msg));
	if (err < 0) {
		netdev_err(netdev, "sending command message failed\n");
		goto failed;
	}

	err = usb_8dev_wait_cmd_msg(priv, priv->cmd_msg_buffer,
				    sizeof(struct usb_8dev_cmd_msg),
				    &num_bytes_read);
	if (err < 0) {
		netdev_err(netdev, "no command message answer\n");
		goto failed;
	}

	memcpy(in, priv->cmd_msg_buffer, sizeof(struct usb_8dev_cmd_msg));

	if (in->begin != USB_8DEV_CMD_START || in->end != USB_8DEV_CMD_END ||
			num_bytes_read != 16 || in->opt1 != 0)
		err = -EPROTO;

failed:
	mutex_unlock(&priv->usb_8dev_cmd_lock);
	return err;
}

/* Send open command to device */
static int usb_8dev_cmd_open(struct usb_8dev_priv *priv)
{
	struct can_bittiming *bt = &priv->can.bittiming;
	struct usb_8dev_cmd_msg outmsg;
	struct usb_8dev_cmd_msg inmsg;
	u32 ctrlmode = priv->can.ctrlmode;
	u32 flags = USB_8DEV_STATUS_FRAME;
	__be32 beflags;
	__be16 bebrp;

	memset(&outmsg, 0, sizeof(outmsg));
	outmsg.command = USB_8DEV_OPEN;
	outmsg.opt1 = USB_8DEV_BAUD_MANUAL;
	outmsg.data[0] = bt->prop_seg + bt->phase_seg1;
	outmsg.data[1] = bt->phase_seg2;
	outmsg.data[2] = bt->sjw;

	/* BRP */
	bebrp = cpu_to_be16((u16)bt->brp);
	memcpy(&outmsg.data[3], &bebrp, sizeof(bebrp));

	/* flags */
	if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
		flags |= USB_8DEV_LOOPBACK;
	if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
		flags |= USB_8DEV_SILENT;
	if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
		flags |= USB_8DEV_DISABLE_AUTO_RESTRANS;

	beflags = cpu_to_be32(flags);
	memcpy(&outmsg.data[5], &beflags, sizeof(beflags));

	return usb_8dev_send_cmd(priv, &outmsg, &inmsg);
}

/* Send close command to device */
static int usb_8dev_cmd_close(struct usb_8dev_priv *priv)
{
	struct usb_8dev_cmd_msg inmsg;
	struct usb_8dev_cmd_msg outmsg = {
		.channel = 0,
		.command = USB_8DEV_CLOSE,
		.opt1 = 0,
		.opt2 = 0
	};

	return usb_8dev_send_cmd(priv, &outmsg, &inmsg);
}

/* Get firmware and hardware version */
static int usb_8dev_cmd_version(struct usb_8dev_priv *priv, u32 *res)
{
	struct usb_8dev_cmd_msg	inmsg;
	struct usb_8dev_cmd_msg	outmsg = {
		.channel = 0,
		.command = USB_8DEV_GET_SOFTW_HARDW_VER,
		.opt1 = 0,
		.opt2 = 0
	};

	int err = usb_8dev_send_cmd(priv, &outmsg, &inmsg);
	if (err)
		return err;

	*res = be32_to_cpup((__be32 *)inmsg.data);

	return err;
}

/* Set network device mode
 *
 * Maybe we should leave this function empty, because the device
 * set mode variable with open command.
 */
static int usb_8dev_set_mode(struct net_device *netdev, enum can_mode mode)
{
	struct usb_8dev_priv *priv = netdev_priv(netdev);
	int err = 0;

	switch (mode) {
	case CAN_MODE_START:
		err = usb_8dev_cmd_open(priv);
		if (err)
			netdev_warn(netdev, "couldn't start device");
		break;

	default:
		return -EOPNOTSUPP;
	}

	return err;
}

/* Read error/status frames */
static void usb_8dev_rx_err_msg(struct usb_8dev_priv *priv,
				struct usb_8dev_rx_msg *msg)
{
	struct can_frame *cf;
	struct sk_buff *skb;
	struct net_device_stats *stats = &priv->netdev->stats;

	/* Error message:
	 * byte 0: Status
	 * byte 1: bit   7: Receive Passive
	 * byte 1: bit 0-6: Receive Error Counter
	 * byte 2: Transmit Error Counter
	 * byte 3: Always 0 (maybe reserved for future use)
	 */

	u8 state = msg->data[0];
	u8 rxerr = msg->data[1] & USB_8DEV_RP_MASK;
	u8 txerr = msg->data[2];
	int rx_errors = 0;
	int tx_errors = 0;

	skb = alloc_can_err_skb(priv->netdev, &cf);
	if (!skb)
		return;

	switch (state) {
	case USB_8DEV_STATUSMSG_OK:
		priv->can.state = CAN_STATE_ERROR_ACTIVE;
		cf->can_id |= CAN_ERR_PROT;
		cf->data[2] = CAN_ERR_PROT_ACTIVE;
		break;
	case USB_8DEV_STATUSMSG_BUSOFF:
		priv->can.state = CAN_STATE_BUS_OFF;
		cf->can_id |= CAN_ERR_BUSOFF;
		priv->can.can_stats.bus_off++;
		can_bus_off(priv->netdev);
		break;
	case USB_8DEV_STATUSMSG_OVERRUN:
	case USB_8DEV_STATUSMSG_BUSLIGHT:
	case USB_8DEV_STATUSMSG_BUSHEAVY:
		cf->can_id |= CAN_ERR_CRTL;
		break;
	default:
		priv->can.state = CAN_STATE_ERROR_WARNING;
		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
		priv->can.can_stats.bus_error++;
		break;
	}

	switch (state) {
	case USB_8DEV_STATUSMSG_OK:
	case USB_8DEV_STATUSMSG_BUSOFF:
		break;
	case USB_8DEV_STATUSMSG_ACK:
		cf->can_id |= CAN_ERR_ACK;
		tx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_CRC:
		cf->data[2] |= CAN_ERR_PROT_UNSPEC;
		cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ |
			       CAN_ERR_PROT_LOC_CRC_DEL;
		rx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_BIT0:
		cf->data[2] |= CAN_ERR_PROT_BIT0;
		tx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_BIT1:
		cf->data[2] |= CAN_ERR_PROT_BIT1;
		tx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_FORM:
		cf->data[2] |= CAN_ERR_PROT_FORM;
		rx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_STUFF:
		cf->data[2] |= CAN_ERR_PROT_STUFF;
		rx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_OVERRUN:
		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
		stats->rx_over_errors++;
		rx_errors = 1;
		break;
	case USB_8DEV_STATUSMSG_BUSLIGHT:
		priv->can.state = CAN_STATE_ERROR_WARNING;
		cf->data[1] = (txerr > rxerr) ?
			CAN_ERR_CRTL_TX_WARNING :
			CAN_ERR_CRTL_RX_WARNING;
		priv->can.can_stats.error_warning++;
		break;
	case USB_8DEV_STATUSMSG_BUSHEAVY:
		priv->can.state = CAN_STATE_ERROR_PASSIVE;
		cf->data[1] = (txerr > rxerr) ?
			CAN_ERR_CRTL_TX_PASSIVE :
			CAN_ERR_CRTL_RX_PASSIVE;
		priv->can.can_stats.error_passive++;
		break;
	default:
		netdev_warn(priv->netdev,
			    "Unknown status/error message (%d)\n", state);
		break;
	}

	if (tx_errors) {
		cf->data[2] |= CAN_ERR_PROT_TX;
		stats->tx_errors++;
	}

	if (rx_errors)
		stats->rx_errors++;

	cf->data[6] = txerr;
	cf->data[7] = rxerr;

	priv->bec.txerr = txerr;
	priv->bec.rxerr = rxerr;

	stats->rx_packets++;
	stats->rx_bytes += cf->can_dlc;
	netif_rx(skb);
}

/* Read data and status frames */
static void usb_8dev_rx_can_msg(struct usb_8dev_priv *priv,
				struct usb_8dev_rx_msg *msg)
{
	struct can_frame *cf;
	struct sk_buff *skb;
	struct net_device_stats *stats = &priv->netdev->stats;

	if (msg->type == USB_8DEV_TYPE_ERROR_FRAME &&
		   msg->flags == USB_8DEV_ERR_FLAG) {
		usb_8dev_rx_err_msg(priv, msg);
	} else if (msg->type == USB_8DEV_TYPE_CAN_FRAME) {
		skb = alloc_can_skb(priv->netdev, &cf);
		if (!skb)
			return;

		cf->can_id = be32_to_cpu(msg->id);
		cf->can_dlc = get_can_dlc(msg->dlc & 0xF);

		if (msg->flags & USB_8DEV_EXTID)
			cf->can_id |= CAN_EFF_FLAG;

		if (msg->flags & USB_8DEV_RTR)
			cf->can_id |= CAN_RTR_FLAG;
		else
			memcpy(cf->data, msg->data, cf->can_dlc);

		stats->rx_packets++;
		stats->rx_bytes += cf->can_dlc;
		netif_rx(skb);

		can_led_event(priv->netdev, CAN_LED_EVENT_RX);
	} else {
		netdev_warn(priv->netdev, "frame type %d unknown",
			 msg->type);
	}

}

/* Callback for reading data from device
 *
 * Check urb status, call read function and resubmit urb read operation.
 */
static void usb_8dev_read_bulk_callback(struct urb *urb)
{
	struct usb_8dev_priv *priv = urb->context;
	struct net_device *netdev;
	int retval;
	int pos = 0;

	netdev = priv->netdev;

	if (!netif_device_present(netdev))
		return;

	switch (urb->status) {
	case 0: /* success */
		break;

	case -ENOENT:
	case -ESHUTDOWN:
		return;

	default:
		netdev_info(netdev, "Rx URB aborted (%d)\n",
			 urb->status);
		goto resubmit_urb;
	}

	while (pos < urb->actual_length) {
		struct usb_8dev_rx_msg *msg;

		if (pos + sizeof(struct usb_8dev_rx_msg) > urb->actual_length) {
			netdev_err(priv->netdev, "format error\n");
			break;
		}

		msg = (struct usb_8dev_rx_msg *)(urb->transfer_buffer + pos);
		usb_8dev_rx_can_msg(priv, msg);

		pos += sizeof(struct usb_8dev_rx_msg);
	}

resubmit_urb:
	usb_fill_bulk_urb(urb, priv->udev,
			  usb_rcvbulkpipe(priv->udev, USB_8DEV_ENDP_DATA_RX),
			  urb->transfer_buffer, RX_BUFFER_SIZE,
			  usb_8dev_read_bulk_callback, priv);

	retval = usb_submit_urb(urb, GFP_ATOMIC);

	if (retval == -ENODEV)
		netif_device_detach(netdev);
	else if (retval)
		netdev_err(netdev,
			"failed resubmitting read bulk urb: %d\n", retval);
}

/* Callback handler for write operations
 *
 * Free allocated buffers, check transmit status and
 * calculate statistic.
 */
static void usb_8dev_write_bulk_callback(struct urb *urb)
{
	struct usb_8dev_tx_urb_context *context = urb->context;
	struct usb_8dev_priv *priv;
	struct net_device *netdev;

	BUG_ON(!context);

	priv = context->priv;
	netdev = priv->netdev;

	/* free up our allocated buffer */
	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
			  urb->transfer_buffer, urb->transfer_dma);

	atomic_dec(&priv->active_tx_urbs);

	if (!netif_device_present(netdev))
		return;

	if (urb->status)
		netdev_info(netdev, "Tx URB aborted (%d)\n",
			 urb->status);

	netdev->stats.tx_packets++;
	netdev->stats.tx_bytes += context->dlc;

	can_get_echo_skb(netdev, context->echo_index);

	can_led_event(netdev, CAN_LED_EVENT_TX);

	/* Release context */
	context->echo_index = MAX_TX_URBS;

	netif_wake_queue(netdev);
}

/* Send data to device */
static netdev_tx_t usb_8dev_start_xmit(struct sk_buff *skb,
				      struct net_device *netdev)
{
	struct usb_8dev_priv *priv = netdev_priv(netdev);
	struct net_device_stats *stats = &netdev->stats;
	struct can_frame *cf = (struct can_frame *) skb->data;
	struct usb_8dev_tx_msg *msg;
	struct urb *urb;
	struct usb_8dev_tx_urb_context *context = NULL;
	u8 *buf;
	int i, err;
	size_t size = sizeof(struct usb_8dev_tx_msg);

	if (can_dropped_invalid_skb(netdev, skb))
		return NETDEV_TX_OK;

	/* create a URB, and a buffer for it, and copy the data to the URB */
	urb = usb_alloc_urb(0, GFP_ATOMIC);
	if (!urb) {
		netdev_err(netdev, "No memory left for URBs\n");
		goto nomem;
	}

	buf = usb_alloc_coherent(priv->udev, size, GFP_ATOMIC,
				 &urb->transfer_dma);
	if (!buf) {
		netdev_err(netdev, "No memory left for USB buffer\n");
		goto nomembuf;
	}

	memset(buf, 0, size);

	msg = (struct usb_8dev_tx_msg *)buf;
	msg->begin = USB_8DEV_DATA_START;
	msg->flags = 0x00;

	if (cf->can_id & CAN_RTR_FLAG)
		msg->flags |= USB_8DEV_RTR;

	if (cf->can_id & CAN_EFF_FLAG)
		msg->flags |= USB_8DEV_EXTID;

	msg->id = cpu_to_be32(cf->can_id & CAN_ERR_MASK);
	msg->dlc = cf->can_dlc;
	memcpy(msg->data, cf->data, cf->can_dlc);
	msg->end = USB_8DEV_DATA_END;

	for (i = 0; i < MAX_TX_URBS; i++) {
		if (priv->tx_contexts[i].echo_index == MAX_TX_URBS) {
			context = &priv->tx_contexts[i];
			break;
		}
	}

	/* May never happen! When this happens we'd more URBs in flight as
	 * allowed (MAX_TX_URBS).
	 */
	if (!context)
		goto nofreecontext;

	context->priv = priv;
	context->echo_index = i;
	context->dlc = cf->can_dlc;

	usb_fill_bulk_urb(urb, priv->udev,
			  usb_sndbulkpipe(priv->udev, USB_8DEV_ENDP_DATA_TX),
			  buf, size, usb_8dev_write_bulk_callback, context);
	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
	usb_anchor_urb(urb, &priv->tx_submitted);

	can_put_echo_skb(skb, netdev, context->echo_index);

	atomic_inc(&priv->active_tx_urbs);

	err = usb_submit_urb(urb, GFP_ATOMIC);
	if (unlikely(err))
		goto failed;
	else if (atomic_read(&priv->active_tx_urbs) >= MAX_TX_URBS)
		/* Slow down tx path */
		netif_stop_queue(netdev);

	/* Release our reference to this URB, the USB core will eventually free
	 * it entirely.
	 */
	usb_free_urb(urb);

	return NETDEV_TX_OK;

nofreecontext:
	usb_free_coherent(priv->udev, size, buf, urb->transfer_dma);
	usb_free_urb(urb);

	netdev_warn(netdev, "couldn't find free context");

	return NETDEV_TX_BUSY;

failed:
	can_free_echo_skb(netdev, context->echo_index);

	usb_unanchor_urb(urb);
	usb_free_coherent(priv->udev, size, buf, urb->transfer_dma);

	atomic_dec(&priv->active_tx_urbs);

	if (err == -ENODEV)
		netif_device_detach(netdev);
	else
		netdev_warn(netdev, "failed tx_urb %d\n", err);

nomembuf:
	usb_free_urb(urb);

nomem:
	dev_kfree_skb(skb);
	stats->tx_dropped++;

	return NETDEV_TX_OK;
}

static int usb_8dev_get_berr_counter(const struct net_device *netdev,
				     struct can_berr_counter *bec)
{
	struct usb_8dev_priv *priv = netdev_priv(netdev);

	bec->txerr = priv->bec.txerr;
	bec->rxerr = priv->bec.rxerr;

	return 0;
}

/* Start USB device */
static int usb_8dev_start(struct usb_8dev_priv *priv)
{
	struct net_device *netdev = priv->netdev;
	int err, i;

	for (i = 0; i < MAX_RX_URBS; i++) {
		struct urb *urb = NULL;
		u8 *buf;

		/* create a URB, and a buffer for it */
		urb = usb_alloc_urb(0, GFP_KERNEL);
		if (!urb) {
			netdev_err(netdev, "No memory left for URBs\n");
			err = -ENOMEM;
			break;
		}

		buf = usb_alloc_coherent(priv->udev, RX_BUFFER_SIZE, GFP_KERNEL,
					 &urb->transfer_dma);
		if (!buf) {
			netdev_err(netdev, "No memory left for USB buffer\n");
			usb_free_urb(urb);
			err = -ENOMEM;
			break;
		}

		usb_fill_bulk_urb(urb, priv->udev,
				  usb_rcvbulkpipe(priv->udev,
						  USB_8DEV_ENDP_DATA_RX),
				  buf, RX_BUFFER_SIZE,
				  usb_8dev_read_bulk_callback, priv);
		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
		usb_anchor_urb(urb, &priv->rx_submitted);

		err = usb_submit_urb(urb, GFP_KERNEL);
		if (err) {
			usb_unanchor_urb(urb);
			usb_free_coherent(priv->udev, RX_BUFFER_SIZE, buf,
					  urb->transfer_dma);
			usb_free_urb(urb);
			break;
		}

		/* Drop reference, USB core will take care of freeing it */
		usb_free_urb(urb);
	}

	/* Did we submit any URBs */
	if (i == 0) {
		netdev_warn(netdev, "couldn't setup read URBs\n");
		return err;
	}

	/* Warn if we've couldn't transmit all the URBs */
	if (i < MAX_RX_URBS)
		netdev_warn(netdev, "rx performance may be slow\n");

	err = usb_8dev_cmd_open(priv);
	if (err)
		goto failed;

	priv->can.state = CAN_STATE_ERROR_ACTIVE;

	return 0;

failed:
	if (err == -ENODEV)
		netif_device_detach(priv->netdev);

	netdev_warn(netdev, "couldn't submit control: %d\n", err);

	return err;
}

/* Open USB device */
static int usb_8dev_open(struct net_device *netdev)
{
	struct usb_8dev_priv *priv = netdev_priv(netdev);
	int err;

	/* common open */
	err = open_candev(netdev);
	if (err)
		return err;

	can_led_event(netdev, CAN_LED_EVENT_OPEN);

	/* finally start device */
	err = usb_8dev_start(priv);
	if (err) {
		if (err == -ENODEV)
			netif_device_detach(priv->netdev);

		netdev_warn(netdev, "couldn't start device: %d\n",
			 err);

		close_candev(netdev);

		return err;
	}

	netif_start_queue(netdev);

	return 0;
}

static void unlink_all_urbs(struct usb_8dev_priv *priv)
{
	int i;

	usb_kill_anchored_urbs(&priv->rx_submitted);

	usb_kill_anchored_urbs(&priv->tx_submitted);
	atomic_set(&priv->active_tx_urbs, 0);

	for (i = 0; i < MAX_TX_URBS; i++)
		priv->tx_contexts[i].echo_index = MAX_TX_URBS;
}

/* Close USB device */
static int usb_8dev_close(struct net_device *netdev)
{
	struct usb_8dev_priv *priv = netdev_priv(netdev);
	int err = 0;

	/* Send CLOSE command to CAN controller */
	err = usb_8dev_cmd_close(priv);
	if (err)
		netdev_warn(netdev, "couldn't stop device");

	priv->can.state = CAN_STATE_STOPPED;

	netif_stop_queue(netdev);

	/* Stop polling */
	unlink_all_urbs(priv);

	close_candev(netdev);

	can_led_event(netdev, CAN_LED_EVENT_STOP);

	return err;
}

static const struct net_device_ops usb_8dev_netdev_ops = {
	.ndo_open = usb_8dev_open,
	.ndo_stop = usb_8dev_close,
	.ndo_start_xmit = usb_8dev_start_xmit,
	.ndo_change_mtu = can_change_mtu,
};

static const struct can_bittiming_const usb_8dev_bittiming_const = {
	.name = "usb_8dev",
	.tseg1_min = 1,
	.tseg1_max = 16,
	.tseg2_min = 1,
	.tseg2_max = 8,
	.sjw_max = 4,
	.brp_min = 1,
	.brp_max = 1024,
	.brp_inc = 1,
};

/* Probe USB device
 *
 * Check device and firmware.
 * Set supported modes and bittiming constants.
 * Allocate some memory.
 */
static int usb_8dev_probe(struct usb_interface *intf,
			 const struct usb_device_id *id)
{
	struct net_device *netdev;
	struct usb_8dev_priv *priv;
	int i, err = -ENOMEM;
	u32 version;
	char buf[18];
	struct usb_device *usbdev = interface_to_usbdev(intf);

	/* product id looks strange, better we also check iProduct string */
	if (usb_string(usbdev, usbdev->descriptor.iProduct, buf,
		       sizeof(buf)) > 0 && strcmp(buf, "USB2CAN converter")) {
		dev_info(&usbdev->dev, "ignoring: not an USB2CAN converter\n");
		return -ENODEV;
	}

	netdev = alloc_candev(sizeof(struct usb_8dev_priv), MAX_TX_URBS);
	if (!netdev) {
		dev_err(&intf->dev, "Couldn't alloc candev\n");
		return -ENOMEM;
	}

	priv = netdev_priv(netdev);

	priv->udev = usbdev;
	priv->netdev = netdev;

	priv->can.state = CAN_STATE_STOPPED;
	priv->can.clock.freq = USB_8DEV_ABP_CLOCK;
	priv->can.bittiming_const = &usb_8dev_bittiming_const;
	priv->can.do_set_mode = usb_8dev_set_mode;
	priv->can.do_get_berr_counter = usb_8dev_get_berr_counter;
	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
				      CAN_CTRLMODE_LISTENONLY |
				      CAN_CTRLMODE_ONE_SHOT;

	netdev->netdev_ops = &usb_8dev_netdev_ops;

	netdev->flags |= IFF_ECHO; /* we support local echo */

	init_usb_anchor(&priv->rx_submitted);

	init_usb_anchor(&priv->tx_submitted);
	atomic_set(&priv->active_tx_urbs, 0);

	for (i = 0; i < MAX_TX_URBS; i++)
		priv->tx_contexts[i].echo_index = MAX_TX_URBS;

	priv->cmd_msg_buffer = kzalloc(sizeof(struct usb_8dev_cmd_msg),
				      GFP_KERNEL);
	if (!priv->cmd_msg_buffer)
		goto cleanup_candev;

	usb_set_intfdata(intf, priv);

	SET_NETDEV_DEV(netdev, &intf->dev);

	mutex_init(&priv->usb_8dev_cmd_lock);

	err = register_candev(netdev);
	if (err) {
		netdev_err(netdev,
			"couldn't register CAN device: %d\n", err);
		goto cleanup_cmd_msg_buffer;
	}

	err = usb_8dev_cmd_version(priv, &version);
	if (err) {
		netdev_err(netdev, "can't get firmware version\n");
		goto cleanup_unregister_candev;
	} else {
		netdev_info(netdev,
			 "firmware: %d.%d, hardware: %d.%d\n",
			 (version>>24) & 0xff, (version>>16) & 0xff,
			 (version>>8) & 0xff, version & 0xff);
	}

	devm_can_led_init(netdev);

	return 0;

cleanup_unregister_candev:
	unregister_netdev(priv->netdev);

cleanup_cmd_msg_buffer:
	kfree(priv->cmd_msg_buffer);

cleanup_candev:
	free_candev(netdev);

	return err;

}

/* Called by the usb core when driver is unloaded or device is removed */
static void usb_8dev_disconnect(struct usb_interface *intf)
{
	struct usb_8dev_priv *priv = usb_get_intfdata(intf);

	usb_set_intfdata(intf, NULL);

	if (priv) {
		netdev_info(priv->netdev, "device disconnected\n");

		unregister_netdev(priv->netdev);
		free_candev(priv->netdev);

		unlink_all_urbs(priv);
	}

}

static struct usb_driver usb_8dev_driver = {
	.name =		"usb_8dev",
	.probe =	usb_8dev_probe,
	.disconnect =	usb_8dev_disconnect,
	.id_table =	usb_8dev_table,
};

module_usb_driver(usb_8dev_driver);

MODULE_AUTHOR("Bernd Krumboeck <krumboeck@universalnet.at>");
MODULE_DESCRIPTION("CAN driver for 8 devices USB2CAN interfaces");
MODULE_LICENSE("GPL v2");