summaryrefslogtreecommitdiffstats
path: root/drivers/net/can/dev.c
blob: 611d16a7061de5cb45f5e7bf7903b45472657965 (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
/*
 * Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/workqueue.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
#include <linux/can/netlink.h>
#include <linux/can/led.h>
#include <net/rtnetlink.h>

#define MOD_DESC "CAN device driver interface"

MODULE_DESCRIPTION(MOD_DESC);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");

/* CAN DLC to real data length conversion helpers */

static const u8 dlc2len[] = {0, 1, 2, 3, 4, 5, 6, 7,
			     8, 12, 16, 20, 24, 32, 48, 64};

/* get data length from can_dlc with sanitized can_dlc */
u8 can_dlc2len(u8 can_dlc)
{
	return dlc2len[can_dlc & 0x0F];
}
EXPORT_SYMBOL_GPL(can_dlc2len);

static const u8 len2dlc[] = {0, 1, 2, 3, 4, 5, 6, 7, 8,		/* 0 - 8 */
			     9, 9, 9, 9,			/* 9 - 12 */
			     10, 10, 10, 10,			/* 13 - 16 */
			     11, 11, 11, 11,			/* 17 - 20 */
			     12, 12, 12, 12,			/* 21 - 24 */
			     13, 13, 13, 13, 13, 13, 13, 13,	/* 25 - 32 */
			     14, 14, 14, 14, 14, 14, 14, 14,	/* 33 - 40 */
			     14, 14, 14, 14, 14, 14, 14, 14,	/* 41 - 48 */
			     15, 15, 15, 15, 15, 15, 15, 15,	/* 49 - 56 */
			     15, 15, 15, 15, 15, 15, 15, 15};	/* 57 - 64 */

/* map the sanitized data length to an appropriate data length code */
u8 can_len2dlc(u8 len)
{
	if (unlikely(len > 64))
		return 0xF;

	return len2dlc[len];
}
EXPORT_SYMBOL_GPL(can_len2dlc);

#ifdef CONFIG_CAN_CALC_BITTIMING
#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
#define CAN_CALC_SYNC_SEG 1

/*
 * Bit-timing calculation derived from:
 *
 * Code based on LinCAN sources and H8S2638 project
 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
 * Copyright 2005      Stanislav Marek
 * email: pisa@cmp.felk.cvut.cz
 *
 * Calculates proper bit-timing parameters for a specified bit-rate
 * and sample-point, which can then be used to set the bit-timing
 * registers of the CAN controller. You can find more information
 * in the header file linux/can/netlink.h.
 */
static int can_update_sample_point(const struct can_bittiming_const *btc,
			  unsigned int sample_point_nominal, unsigned int tseg,
			  unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
			  unsigned int *sample_point_error_ptr)
{
	unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
	unsigned int sample_point, best_sample_point = 0;
	unsigned int tseg1, tseg2;
	int i;

	for (i = 0; i <= 1; i++) {
		tseg2 = tseg + CAN_CALC_SYNC_SEG - (sample_point_nominal * (tseg + CAN_CALC_SYNC_SEG)) / 1000 - i;
		tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
		tseg1 = tseg - tseg2;
		if (tseg1 > btc->tseg1_max) {
			tseg1 = btc->tseg1_max;
			tseg2 = tseg - tseg1;
		}

		sample_point = 1000 * (tseg + CAN_CALC_SYNC_SEG - tseg2) / (tseg + CAN_CALC_SYNC_SEG);
		sample_point_error = abs(sample_point_nominal - sample_point);

		if ((sample_point <= sample_point_nominal) && (sample_point_error < best_sample_point_error)) {
			best_sample_point = sample_point;
			best_sample_point_error = sample_point_error;
			*tseg1_ptr = tseg1;
			*tseg2_ptr = tseg2;
		}
	}

	if (sample_point_error_ptr)
		*sample_point_error_ptr = best_sample_point_error;

	return best_sample_point;
}

static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
			      const struct can_bittiming_const *btc)
{
	struct can_priv *priv = netdev_priv(dev);
	unsigned int bitrate;			/* current bitrate */
	unsigned int bitrate_error;		/* difference between current and nominal value */
	unsigned int best_bitrate_error = UINT_MAX;
	unsigned int sample_point_error;	/* difference between current and nominal value */
	unsigned int best_sample_point_error = UINT_MAX;
	unsigned int sample_point_nominal;	/* nominal sample point */
	unsigned int best_tseg = 0;		/* current best value for tseg */
	unsigned int best_brp = 0;		/* current best value for brp */
	unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;
	u64 v64;

	/* Use CiA recommended sample points */
	if (bt->sample_point) {
		sample_point_nominal = bt->sample_point;
	} else {
		if (bt->bitrate > 800000)
			sample_point_nominal = 750;
		else if (bt->bitrate > 500000)
			sample_point_nominal = 800;
		else
			sample_point_nominal = 875;
	}

	/* tseg even = round down, odd = round up */
	for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
	     tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
		tsegall = CAN_CALC_SYNC_SEG + tseg / 2;

		/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
		brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;

		/* choose brp step which is possible in system */
		brp = (brp / btc->brp_inc) * btc->brp_inc;
		if ((brp < btc->brp_min) || (brp > btc->brp_max))
			continue;

		bitrate = priv->clock.freq / (brp * tsegall);
		bitrate_error = abs(bt->bitrate - bitrate);

		/* tseg brp biterror */
		if (bitrate_error > best_bitrate_error)
			continue;

		/* reset sample point error if we have a better bitrate */
		if (bitrate_error < best_bitrate_error)
			best_sample_point_error = UINT_MAX;

		can_update_sample_point(btc, sample_point_nominal, tseg / 2, &tseg1, &tseg2, &sample_point_error);
		if (sample_point_error > best_sample_point_error)
			continue;

		best_sample_point_error = sample_point_error;
		best_bitrate_error = bitrate_error;
		best_tseg = tseg / 2;
		best_brp = brp;

		if (bitrate_error == 0 && sample_point_error == 0)
			break;
	}

	if (best_bitrate_error) {
		/* Error in one-tenth of a percent */
		v64 = (u64)best_bitrate_error * 1000;
		do_div(v64, bt->bitrate);
		bitrate_error = (u32)v64;
		if (bitrate_error > CAN_CALC_MAX_ERROR) {
			netdev_err(dev,
				   "bitrate error %d.%d%% too high\n",
				   bitrate_error / 10, bitrate_error % 10);
			return -EDOM;
		}
		netdev_warn(dev, "bitrate error %d.%d%%\n",
			    bitrate_error / 10, bitrate_error % 10);
	}

	/* real sample point */
	bt->sample_point = can_update_sample_point(btc, sample_point_nominal, best_tseg,
					  &tseg1, &tseg2, NULL);

	v64 = (u64)best_brp * 1000 * 1000 * 1000;
	do_div(v64, priv->clock.freq);
	bt->tq = (u32)v64;
	bt->prop_seg = tseg1 / 2;
	bt->phase_seg1 = tseg1 - bt->prop_seg;
	bt->phase_seg2 = tseg2;

	/* check for sjw user settings */
	if (!bt->sjw || !btc->sjw_max) {
		bt->sjw = 1;
	} else {
		/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
		if (bt->sjw > btc->sjw_max)
			bt->sjw = btc->sjw_max;
		/* bt->sjw must not be higher than tseg2 */
		if (tseg2 < bt->sjw)
			bt->sjw = tseg2;
	}

	bt->brp = best_brp;

	/* real bitrate */
	bt->bitrate = priv->clock.freq / (bt->brp * (CAN_CALC_SYNC_SEG + tseg1 + tseg2));

	return 0;
}
#else /* !CONFIG_CAN_CALC_BITTIMING */
static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
			      const struct can_bittiming_const *btc)
{
	netdev_err(dev, "bit-timing calculation not available\n");
	return -EINVAL;
}
#endif /* CONFIG_CAN_CALC_BITTIMING */

/*
 * Checks the validity of the specified bit-timing parameters prop_seg,
 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
 * prescaler value brp. You can find more information in the header
 * file linux/can/netlink.h.
 */
static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
			       const struct can_bittiming_const *btc)
{
	struct can_priv *priv = netdev_priv(dev);
	int tseg1, alltseg;
	u64 brp64;

	tseg1 = bt->prop_seg + bt->phase_seg1;
	if (!bt->sjw)
		bt->sjw = 1;
	if (bt->sjw > btc->sjw_max ||
	    tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
	    bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
		return -ERANGE;

	brp64 = (u64)priv->clock.freq * (u64)bt->tq;
	if (btc->brp_inc > 1)
		do_div(brp64, btc->brp_inc);
	brp64 += 500000000UL - 1;
	do_div(brp64, 1000000000UL); /* the practicable BRP */
	if (btc->brp_inc > 1)
		brp64 *= btc->brp_inc;
	bt->brp = (u32)brp64;

	if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
		return -EINVAL;

	alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
	bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
	bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;

	return 0;
}

/* Checks the validity of predefined bitrate settings */
static int can_validate_bitrate(struct net_device *dev, struct can_bittiming *bt,
				const u32 *bitrate_const,
				const unsigned int bitrate_const_cnt)
{
	struct can_priv *priv = netdev_priv(dev);
	unsigned int i;

	for (i = 0; i < bitrate_const_cnt; i++) {
		if (bt->bitrate == bitrate_const[i])
			break;
	}

	if (i >= priv->bitrate_const_cnt)
		return -EINVAL;

	return 0;
}

static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
			     const struct can_bittiming_const *btc,
			     const u32 *bitrate_const,
			     const unsigned int bitrate_const_cnt)
{
	int err;

	/*
	 * Depending on the given can_bittiming parameter structure the CAN
	 * timing parameters are calculated based on the provided bitrate OR
	 * alternatively the CAN timing parameters (tq, prop_seg, etc.) are
	 * provided directly which are then checked and fixed up.
	 */
	if (!bt->tq && bt->bitrate && btc)
		err = can_calc_bittiming(dev, bt, btc);
	else if (bt->tq && !bt->bitrate && btc)
		err = can_fixup_bittiming(dev, bt, btc);
	else if (!bt->tq && bt->bitrate && bitrate_const)
		err = can_validate_bitrate(dev, bt, bitrate_const,
					   bitrate_const_cnt);
	else
		err = -EINVAL;

	return err;
}

static void can_update_state_error_stats(struct net_device *dev,
					 enum can_state new_state)
{
	struct can_priv *priv = netdev_priv(dev);

	if (new_state <= priv->state)
		return;

	switch (new_state) {
	case CAN_STATE_ERROR_WARNING:
		priv->can_stats.error_warning++;
		break;
	case CAN_STATE_ERROR_PASSIVE:
		priv->can_stats.error_passive++;
		break;
	case CAN_STATE_BUS_OFF:
		priv->can_stats.bus_off++;
		break;
	default:
		break;
	}
}

static int can_tx_state_to_frame(struct net_device *dev, enum can_state state)
{
	switch (state) {
	case CAN_STATE_ERROR_ACTIVE:
		return CAN_ERR_CRTL_ACTIVE;
	case CAN_STATE_ERROR_WARNING:
		return CAN_ERR_CRTL_TX_WARNING;
	case CAN_STATE_ERROR_PASSIVE:
		return CAN_ERR_CRTL_TX_PASSIVE;
	default:
		return 0;
	}
}

static int can_rx_state_to_frame(struct net_device *dev, enum can_state state)
{
	switch (state) {
	case CAN_STATE_ERROR_ACTIVE:
		return CAN_ERR_CRTL_ACTIVE;
	case CAN_STATE_ERROR_WARNING:
		return CAN_ERR_CRTL_RX_WARNING;
	case CAN_STATE_ERROR_PASSIVE:
		return CAN_ERR_CRTL_RX_PASSIVE;
	default:
		return 0;
	}
}

void can_change_state(struct net_device *dev, struct can_frame *cf,
		      enum can_state tx_state, enum can_state rx_state)
{
	struct can_priv *priv = netdev_priv(dev);
	enum can_state new_state = max(tx_state, rx_state);

	if (unlikely(new_state == priv->state)) {
		netdev_warn(dev, "%s: oops, state did not change", __func__);
		return;
	}

	netdev_dbg(dev, "New error state: %d\n", new_state);

	can_update_state_error_stats(dev, new_state);
	priv->state = new_state;

	if (unlikely(new_state == CAN_STATE_BUS_OFF)) {
		cf->can_id |= CAN_ERR_BUSOFF;
		return;
	}

	cf->can_id |= CAN_ERR_CRTL;
	cf->data[1] |= tx_state >= rx_state ?
		       can_tx_state_to_frame(dev, tx_state) : 0;
	cf->data[1] |= tx_state <= rx_state ?
		       can_rx_state_to_frame(dev, rx_state) : 0;
}
EXPORT_SYMBOL_GPL(can_change_state);

/*
 * Local echo of CAN messages
 *
 * CAN network devices *should* support a local echo functionality
 * (see Documentation/networking/can.txt). To test the handling of CAN
 * interfaces that do not support the local echo both driver types are
 * implemented. In the case that the driver does not support the echo
 * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
 * to perform the echo as a fallback solution.
 */
static void can_flush_echo_skb(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	int i;

	for (i = 0; i < priv->echo_skb_max; i++) {
		if (priv->echo_skb[i]) {
			kfree_skb(priv->echo_skb[i]);
			priv->echo_skb[i] = NULL;
			stats->tx_dropped++;
			stats->tx_aborted_errors++;
		}
	}
}

/*
 * Put the skb on the stack to be looped backed locally lateron
 *
 * The function is typically called in the start_xmit function
 * of the device driver. The driver must protect access to
 * priv->echo_skb, if necessary.
 */
void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
		      unsigned int idx)
{
	struct can_priv *priv = netdev_priv(dev);

	BUG_ON(idx >= priv->echo_skb_max);

	/* check flag whether this packet has to be looped back */
	if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK ||
	    (skb->protocol != htons(ETH_P_CAN) &&
	     skb->protocol != htons(ETH_P_CANFD))) {
		kfree_skb(skb);
		return;
	}

	if (!priv->echo_skb[idx]) {

		skb = can_create_echo_skb(skb);
		if (!skb)
			return;

		/* make settings for echo to reduce code in irq context */
		skb->pkt_type = PACKET_BROADCAST;
		skb->ip_summed = CHECKSUM_UNNECESSARY;
		skb->dev = dev;

		/* save this skb for tx interrupt echo handling */
		priv->echo_skb[idx] = skb;
	} else {
		/* locking problem with netif_stop_queue() ?? */
		netdev_err(dev, "%s: BUG! echo_skb is occupied!\n", __func__);
		kfree_skb(skb);
	}
}
EXPORT_SYMBOL_GPL(can_put_echo_skb);

/*
 * Get the skb from the stack and loop it back locally
 *
 * The function is typically called when the TX done interrupt
 * is handled in the device driver. The driver must protect
 * access to priv->echo_skb, if necessary.
 */
unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx)
{
	struct can_priv *priv = netdev_priv(dev);

	BUG_ON(idx >= priv->echo_skb_max);

	if (priv->echo_skb[idx]) {
		struct sk_buff *skb = priv->echo_skb[idx];
		struct can_frame *cf = (struct can_frame *)skb->data;
		u8 dlc = cf->can_dlc;

		netif_rx(priv->echo_skb[idx]);
		priv->echo_skb[idx] = NULL;

		return dlc;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(can_get_echo_skb);

/*
  * Remove the skb from the stack and free it.
  *
  * The function is typically called when TX failed.
  */
void can_free_echo_skb(struct net_device *dev, unsigned int idx)
{
	struct can_priv *priv = netdev_priv(dev);

	BUG_ON(idx >= priv->echo_skb_max);

	if (priv->echo_skb[idx]) {
		dev_kfree_skb_any(priv->echo_skb[idx]);
		priv->echo_skb[idx] = NULL;
	}
}
EXPORT_SYMBOL_GPL(can_free_echo_skb);

/*
 * CAN device restart for bus-off recovery
 */
static void can_restart(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	struct sk_buff *skb;
	struct can_frame *cf;
	int err;

	BUG_ON(netif_carrier_ok(dev));

	/*
	 * No synchronization needed because the device is bus-off and
	 * no messages can come in or go out.
	 */
	can_flush_echo_skb(dev);

	/* send restart message upstream */
	skb = alloc_can_err_skb(dev, &cf);
	if (skb == NULL) {
		err = -ENOMEM;
		goto restart;
	}
	cf->can_id |= CAN_ERR_RESTARTED;

	netif_rx(skb);

	stats->rx_packets++;
	stats->rx_bytes += cf->can_dlc;

restart:
	netdev_dbg(dev, "restarted\n");
	priv->can_stats.restarts++;

	/* Now restart the device */
	err = priv->do_set_mode(dev, CAN_MODE_START);

	netif_carrier_on(dev);
	if (err)
		netdev_err(dev, "Error %d during restart", err);
}

static void can_restart_work(struct work_struct *work)
{
	struct delayed_work *dwork = to_delayed_work(work);
	struct can_priv *priv = container_of(dwork, struct can_priv, restart_work);

	can_restart(priv->dev);
}

int can_restart_now(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);

	/*
	 * A manual restart is only permitted if automatic restart is
	 * disabled and the device is in the bus-off state
	 */
	if (priv->restart_ms)
		return -EINVAL;
	if (priv->state != CAN_STATE_BUS_OFF)
		return -EBUSY;

	cancel_delayed_work_sync(&priv->restart_work);
	can_restart(dev);

	return 0;
}

/*
 * CAN bus-off
 *
 * This functions should be called when the device goes bus-off to
 * tell the netif layer that no more packets can be sent or received.
 * If enabled, a timer is started to trigger bus-off recovery.
 */
void can_bus_off(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);

	netdev_dbg(dev, "bus-off\n");

	netif_carrier_off(dev);

	if (priv->restart_ms)
		schedule_delayed_work(&priv->restart_work,
				      msecs_to_jiffies(priv->restart_ms));
}
EXPORT_SYMBOL_GPL(can_bus_off);

static void can_setup(struct net_device *dev)
{
	dev->type = ARPHRD_CAN;
	dev->mtu = CAN_MTU;
	dev->hard_header_len = 0;
	dev->addr_len = 0;
	dev->tx_queue_len = 10;

	/* New-style flags. */
	dev->flags = IFF_NOARP;
	dev->features = NETIF_F_HW_CSUM;
}

struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
{
	struct sk_buff *skb;

	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
			       sizeof(struct can_frame));
	if (unlikely(!skb))
		return NULL;

	skb->protocol = htons(ETH_P_CAN);
	skb->pkt_type = PACKET_BROADCAST;
	skb->ip_summed = CHECKSUM_UNNECESSARY;

	skb_reset_mac_header(skb);
	skb_reset_network_header(skb);
	skb_reset_transport_header(skb);

	can_skb_reserve(skb);
	can_skb_prv(skb)->ifindex = dev->ifindex;
	can_skb_prv(skb)->skbcnt = 0;

	*cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
	memset(*cf, 0, sizeof(struct can_frame));

	return skb;
}
EXPORT_SYMBOL_GPL(alloc_can_skb);

struct sk_buff *alloc_canfd_skb(struct net_device *dev,
				struct canfd_frame **cfd)
{
	struct sk_buff *skb;

	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
			       sizeof(struct canfd_frame));
	if (unlikely(!skb))
		return NULL;

	skb->protocol = htons(ETH_P_CANFD);
	skb->pkt_type = PACKET_BROADCAST;
	skb->ip_summed = CHECKSUM_UNNECESSARY;

	skb_reset_mac_header(skb);
	skb_reset_network_header(skb);
	skb_reset_transport_header(skb);

	can_skb_reserve(skb);
	can_skb_prv(skb)->ifindex = dev->ifindex;
	can_skb_prv(skb)->skbcnt = 0;

	*cfd = (struct canfd_frame *)skb_put(skb, sizeof(struct canfd_frame));
	memset(*cfd, 0, sizeof(struct canfd_frame));

	return skb;
}
EXPORT_SYMBOL_GPL(alloc_canfd_skb);

struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
{
	struct sk_buff *skb;

	skb = alloc_can_skb(dev, cf);
	if (unlikely(!skb))
		return NULL;

	(*cf)->can_id = CAN_ERR_FLAG;
	(*cf)->can_dlc = CAN_ERR_DLC;

	return skb;
}
EXPORT_SYMBOL_GPL(alloc_can_err_skb);

/*
 * Allocate and setup space for the CAN network device
 */
struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
{
	struct net_device *dev;
	struct can_priv *priv;
	int size;

	if (echo_skb_max)
		size = ALIGN(sizeof_priv, sizeof(struct sk_buff *)) +
			echo_skb_max * sizeof(struct sk_buff *);
	else
		size = sizeof_priv;

	dev = alloc_netdev(size, "can%d", NET_NAME_UNKNOWN, can_setup);
	if (!dev)
		return NULL;

	priv = netdev_priv(dev);
	priv->dev = dev;

	if (echo_skb_max) {
		priv->echo_skb_max = echo_skb_max;
		priv->echo_skb = (void *)priv +
			ALIGN(sizeof_priv, sizeof(struct sk_buff *));
	}

	priv->state = CAN_STATE_STOPPED;

	INIT_DELAYED_WORK(&priv->restart_work, can_restart_work);

	return dev;
}
EXPORT_SYMBOL_GPL(alloc_candev);

/*
 * Free space of the CAN network device
 */
void free_candev(struct net_device *dev)
{
	free_netdev(dev);
}
EXPORT_SYMBOL_GPL(free_candev);

/*
 * changing MTU and control mode for CAN/CANFD devices
 */
int can_change_mtu(struct net_device *dev, int new_mtu)
{
	struct can_priv *priv = netdev_priv(dev);

	/* Do not allow changing the MTU while running */
	if (dev->flags & IFF_UP)
		return -EBUSY;

	/* allow change of MTU according to the CANFD ability of the device */
	switch (new_mtu) {
	case CAN_MTU:
		/* 'CANFD-only' controllers can not switch to CAN_MTU */
		if (priv->ctrlmode_static & CAN_CTRLMODE_FD)
			return -EINVAL;

		priv->ctrlmode &= ~CAN_CTRLMODE_FD;
		break;

	case CANFD_MTU:
		/* check for potential CANFD ability */
		if (!(priv->ctrlmode_supported & CAN_CTRLMODE_FD) &&
		    !(priv->ctrlmode_static & CAN_CTRLMODE_FD))
			return -EINVAL;

		priv->ctrlmode |= CAN_CTRLMODE_FD;
		break;

	default:
		return -EINVAL;
	}

	dev->mtu = new_mtu;
	return 0;
}
EXPORT_SYMBOL_GPL(can_change_mtu);

/*
 * Common open function when the device gets opened.
 *
 * This function should be called in the open function of the device
 * driver.
 */
int open_candev(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);

	if (!priv->bittiming.bitrate) {
		netdev_err(dev, "bit-timing not yet defined\n");
		return -EINVAL;
	}

	/* For CAN FD the data bitrate has to be >= the arbitration bitrate */
	if ((priv->ctrlmode & CAN_CTRLMODE_FD) &&
	    (!priv->data_bittiming.bitrate ||
	     (priv->data_bittiming.bitrate < priv->bittiming.bitrate))) {
		netdev_err(dev, "incorrect/missing data bit-timing\n");
		return -EINVAL;
	}

	/* Switch carrier on if device was stopped while in bus-off state */
	if (!netif_carrier_ok(dev))
		netif_carrier_on(dev);

	return 0;
}
EXPORT_SYMBOL_GPL(open_candev);

/*
 * Common close function for cleanup before the device gets closed.
 *
 * This function should be called in the close function of the device
 * driver.
 */
void close_candev(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);

	cancel_delayed_work_sync(&priv->restart_work);
	can_flush_echo_skb(dev);
}
EXPORT_SYMBOL_GPL(close_candev);

/*
 * CAN netlink interface
 */
static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
	[IFLA_CAN_STATE]	= { .type = NLA_U32 },
	[IFLA_CAN_CTRLMODE]	= { .len = sizeof(struct can_ctrlmode) },
	[IFLA_CAN_RESTART_MS]	= { .type = NLA_U32 },
	[IFLA_CAN_RESTART]	= { .type = NLA_U32 },
	[IFLA_CAN_BITTIMING]	= { .len = sizeof(struct can_bittiming) },
	[IFLA_CAN_BITTIMING_CONST]
				= { .len = sizeof(struct can_bittiming_const) },
	[IFLA_CAN_CLOCK]	= { .len = sizeof(struct can_clock) },
	[IFLA_CAN_BERR_COUNTER]	= { .len = sizeof(struct can_berr_counter) },
	[IFLA_CAN_DATA_BITTIMING]
				= { .len = sizeof(struct can_bittiming) },
	[IFLA_CAN_DATA_BITTIMING_CONST]
				= { .len = sizeof(struct can_bittiming_const) },
};

static int can_validate(struct nlattr *tb[], struct nlattr *data[])
{
	bool is_can_fd = false;

	/* Make sure that valid CAN FD configurations always consist of
	 * - nominal/arbitration bittiming
	 * - data bittiming
	 * - control mode with CAN_CTRLMODE_FD set
	 */

	if (!data)
		return 0;

	if (data[IFLA_CAN_CTRLMODE]) {
		struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);

		is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
	}

	if (is_can_fd) {
		if (!data[IFLA_CAN_BITTIMING] || !data[IFLA_CAN_DATA_BITTIMING])
			return -EOPNOTSUPP;
	}

	if (data[IFLA_CAN_DATA_BITTIMING]) {
		if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
			return -EOPNOTSUPP;
	}

	return 0;
}

static int can_changelink(struct net_device *dev,
			  struct nlattr *tb[], struct nlattr *data[])
{
	struct can_priv *priv = netdev_priv(dev);
	int err;

	/* We need synchronization with dev->stop() */
	ASSERT_RTNL();

	if (data[IFLA_CAN_BITTIMING]) {
		struct can_bittiming bt;

		/* Do not allow changing bittiming while running */
		if (dev->flags & IFF_UP)
			return -EBUSY;

		/* Calculate bittiming parameters based on
		 * bittiming_const if set, otherwise pass bitrate
		 * directly via do_set_bitrate(). Bail out if neither
		 * is given.
		 */
		if (!priv->bittiming_const && !priv->do_set_bittiming)
			return -EOPNOTSUPP;

		memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt));
		err = can_get_bittiming(dev, &bt,
					priv->bittiming_const,
					priv->bitrate_const,
					priv->bitrate_const_cnt);
		if (err)
			return err;
		memcpy(&priv->bittiming, &bt, sizeof(bt));

		if (priv->do_set_bittiming) {
			/* Finally, set the bit-timing registers */
			err = priv->do_set_bittiming(dev);
			if (err)
				return err;
		}
	}

	if (data[IFLA_CAN_CTRLMODE]) {
		struct can_ctrlmode *cm;
		u32 ctrlstatic;
		u32 maskedflags;

		/* Do not allow changing controller mode while running */
		if (dev->flags & IFF_UP)
			return -EBUSY;
		cm = nla_data(data[IFLA_CAN_CTRLMODE]);
		ctrlstatic = priv->ctrlmode_static;
		maskedflags = cm->flags & cm->mask;

		/* check whether provided bits are allowed to be passed */
		if (cm->mask & ~(priv->ctrlmode_supported | ctrlstatic))
			return -EOPNOTSUPP;

		/* do not check for static fd-non-iso if 'fd' is disabled */
		if (!(maskedflags & CAN_CTRLMODE_FD))
			ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;

		/* make sure static options are provided by configuration */
		if ((maskedflags & ctrlstatic) != ctrlstatic)
			return -EOPNOTSUPP;

		/* clear bits to be modified and copy the flag values */
		priv->ctrlmode &= ~cm->mask;
		priv->ctrlmode |= maskedflags;

		/* CAN_CTRLMODE_FD can only be set when driver supports FD */
		if (priv->ctrlmode & CAN_CTRLMODE_FD)
			dev->mtu = CANFD_MTU;
		else
			dev->mtu = CAN_MTU;
	}

	if (data[IFLA_CAN_RESTART_MS]) {
		/* Do not allow changing restart delay while running */
		if (dev->flags & IFF_UP)
			return -EBUSY;
		priv->restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]);
	}

	if (data[IFLA_CAN_RESTART]) {
		/* Do not allow a restart while not running */
		if (!(dev->flags & IFF_UP))
			return -EINVAL;
		err = can_restart_now(dev);
		if (err)
			return err;
	}

	if (data[IFLA_CAN_DATA_BITTIMING]) {
		struct can_bittiming dbt;

		/* Do not allow changing bittiming while running */
		if (dev->flags & IFF_UP)
			return -EBUSY;

		/* Calculate bittiming parameters based on
		 * data_bittiming_const if set, otherwise pass bitrate
		 * directly via do_set_bitrate(). Bail out if neither
		 * is given.
		 */
		if (!priv->data_bittiming_const && !priv->do_set_data_bittiming)
			return -EOPNOTSUPP;

		memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
		       sizeof(dbt));
		err = can_get_bittiming(dev, &dbt,
					priv->data_bittiming_const,
					priv->data_bitrate_const,
					priv->data_bitrate_const_cnt);
		if (err)
			return err;
		memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));

		if (priv->do_set_data_bittiming) {
			/* Finally, set the bit-timing registers */
			err = priv->do_set_data_bittiming(dev);
			if (err)
				return err;
		}
	}

	if (data[IFLA_CAN_TERMINATION]) {
		const u16 termval = nla_get_u16(data[IFLA_CAN_TERMINATION]);
		const unsigned int num_term = priv->termination_const_cnt;
		unsigned int i;

		if (!priv->do_set_termination)
			return -EOPNOTSUPP;

		/* check whether given value is supported by the interface */
		for (i = 0; i < num_term; i++) {
			if (termval == priv->termination_const[i])
				break;
		}
		if (i >= num_term)
			return -EINVAL;

		/* Finally, set the termination value */
		err = priv->do_set_termination(dev, termval);
		if (err)
			return err;

		priv->termination = termval;
	}

	return 0;
}

static size_t can_get_size(const struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);
	size_t size = 0;

	if (priv->bittiming.bitrate)				/* IFLA_CAN_BITTIMING */
		size += nla_total_size(sizeof(struct can_bittiming));
	if (priv->bittiming_const)				/* IFLA_CAN_BITTIMING_CONST */
		size += nla_total_size(sizeof(struct can_bittiming_const));
	size += nla_total_size(sizeof(struct can_clock));	/* IFLA_CAN_CLOCK */
	size += nla_total_size(sizeof(u32));			/* IFLA_CAN_STATE */
	size += nla_total_size(sizeof(struct can_ctrlmode));	/* IFLA_CAN_CTRLMODE */
	size += nla_total_size(sizeof(u32));			/* IFLA_CAN_RESTART_MS */
	if (priv->do_get_berr_counter)				/* IFLA_CAN_BERR_COUNTER */
		size += nla_total_size(sizeof(struct can_berr_counter));
	if (priv->data_bittiming.bitrate)			/* IFLA_CAN_DATA_BITTIMING */
		size += nla_total_size(sizeof(struct can_bittiming));
	if (priv->data_bittiming_const)				/* IFLA_CAN_DATA_BITTIMING_CONST */
		size += nla_total_size(sizeof(struct can_bittiming_const));
	if (priv->termination_const) {
		size += nla_total_size(sizeof(priv->termination));		/* IFLA_CAN_TERMINATION */
		size += nla_total_size(sizeof(*priv->termination_const) *	/* IFLA_CAN_TERMINATION_CONST */
				       priv->termination_const_cnt);
	}
	if (priv->bitrate_const)				/* IFLA_CAN_BITRATE_CONST */
		size += nla_total_size(sizeof(*priv->bitrate_const) *
				       priv->bitrate_const_cnt);
	if (priv->data_bitrate_const)				/* IFLA_CAN_DATA_BITRATE_CONST */
		size += nla_total_size(sizeof(*priv->data_bitrate_const) *
				       priv->data_bitrate_const_cnt);

	return size;
}

static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);
	struct can_ctrlmode cm = {.flags = priv->ctrlmode};
	struct can_berr_counter bec;
	enum can_state state = priv->state;

	if (priv->do_get_state)
		priv->do_get_state(dev, &state);

	if ((priv->bittiming.bitrate &&
	     nla_put(skb, IFLA_CAN_BITTIMING,
		     sizeof(priv->bittiming), &priv->bittiming)) ||

	    (priv->bittiming_const &&
	     nla_put(skb, IFLA_CAN_BITTIMING_CONST,
		     sizeof(*priv->bittiming_const), priv->bittiming_const)) ||

	    nla_put(skb, IFLA_CAN_CLOCK, sizeof(priv->clock), &priv->clock) ||
	    nla_put_u32(skb, IFLA_CAN_STATE, state) ||
	    nla_put(skb, IFLA_CAN_CTRLMODE, sizeof(cm), &cm) ||
	    nla_put_u32(skb, IFLA_CAN_RESTART_MS, priv->restart_ms) ||

	    (priv->do_get_berr_counter &&
	     !priv->do_get_berr_counter(dev, &bec) &&
	     nla_put(skb, IFLA_CAN_BERR_COUNTER, sizeof(bec), &bec)) ||

	    (priv->data_bittiming.bitrate &&
	     nla_put(skb, IFLA_CAN_DATA_BITTIMING,
		     sizeof(priv->data_bittiming), &priv->data_bittiming)) ||

	    (priv->data_bittiming_const &&
	     nla_put(skb, IFLA_CAN_DATA_BITTIMING_CONST,
		     sizeof(*priv->data_bittiming_const),
		     priv->data_bittiming_const)) ||

	    (priv->termination_const &&
	     (nla_put_u16(skb, IFLA_CAN_TERMINATION, priv->termination) ||
	      nla_put(skb, IFLA_CAN_TERMINATION_CONST,
		      sizeof(*priv->termination_const) *
		      priv->termination_const_cnt,
		      priv->termination_const))) ||

	    (priv->bitrate_const &&
	     nla_put(skb, IFLA_CAN_BITRATE_CONST,
		     sizeof(*priv->bitrate_const) *
		     priv->bitrate_const_cnt,
		     priv->bitrate_const)) ||

	    (priv->data_bitrate_const &&
	     nla_put(skb, IFLA_CAN_DATA_BITRATE_CONST,
		     sizeof(*priv->data_bitrate_const) *
		     priv->data_bitrate_const_cnt,
		     priv->data_bitrate_const))
	    )

		return -EMSGSIZE;

	return 0;
}

static size_t can_get_xstats_size(const struct net_device *dev)
{
	return sizeof(struct can_device_stats);
}

static int can_fill_xstats(struct sk_buff *skb, const struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);

	if (nla_put(skb, IFLA_INFO_XSTATS,
		    sizeof(priv->can_stats), &priv->can_stats))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -EMSGSIZE;
}

static int can_newlink(struct net *src_net, struct net_device *dev,
		       struct nlattr *tb[], struct nlattr *data[])
{
	return -EOPNOTSUPP;
}

static void can_dellink(struct net_device *dev, struct list_head *head)
{
	return;
}

static struct rtnl_link_ops can_link_ops __read_mostly = {
	.kind		= "can",
	.maxtype	= IFLA_CAN_MAX,
	.policy		= can_policy,
	.setup		= can_setup,
	.validate	= can_validate,
	.newlink	= can_newlink,
	.changelink	= can_changelink,
	.dellink	= can_dellink,
	.get_size	= can_get_size,
	.fill_info	= can_fill_info,
	.get_xstats_size = can_get_xstats_size,
	.fill_xstats	= can_fill_xstats,
};

/*
 * Register the CAN network device
 */
int register_candev(struct net_device *dev)
{
	struct can_priv *priv = netdev_priv(dev);

	/* Ensure termination_const, termination_const_cnt and
	 * do_set_termination consistency. All must be either set or
	 * unset.
	 */
	if ((!priv->termination_const != !priv->termination_const_cnt) ||
	    (!priv->termination_const != !priv->do_set_termination))
		return -EINVAL;

	if (!priv->bitrate_const != !priv->bitrate_const_cnt)
		return -EINVAL;

	if (!priv->data_bitrate_const != !priv->data_bitrate_const_cnt)
		return -EINVAL;

	dev->rtnl_link_ops = &can_link_ops;
	return register_netdev(dev);
}
EXPORT_SYMBOL_GPL(register_candev);

/*
 * Unregister the CAN network device
 */
void unregister_candev(struct net_device *dev)
{
	unregister_netdev(dev);
}
EXPORT_SYMBOL_GPL(unregister_candev);

/*
 * Test if a network device is a candev based device
 * and return the can_priv* if so.
 */
struct can_priv *safe_candev_priv(struct net_device *dev)
{
	if ((dev->type != ARPHRD_CAN) || (dev->rtnl_link_ops != &can_link_ops))
		return NULL;

	return netdev_priv(dev);
}
EXPORT_SYMBOL_GPL(safe_candev_priv);

static __init int can_dev_init(void)
{
	int err;

	can_led_notifier_init();

	err = rtnl_link_register(&can_link_ops);
	if (!err)
		printk(KERN_INFO MOD_DESC "\n");

	return err;
}
module_init(can_dev_init);

static __exit void can_dev_exit(void)
{
	rtnl_link_unregister(&can_link_ops);

	can_led_notifier_exit();
}
module_exit(can_dev_exit);

MODULE_ALIAS_RTNL_LINK("can");