summaryrefslogtreecommitdiff
path: root/drivers/net/can/peak_canfd/peak_canfd.c
blob: 5696d7e807513a529823ac218f8236bcf52aea8e (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
/*
 * Copyright (C) 2007, 2011 Wolfgang Grandegger <wg@grandegger.com>
 * Copyright (C) 2012 Stephane Grosjean <s.grosjean@peak-system.com>
 *
 * Copyright (C) 2016  PEAK System-Technik GmbH
 *
 * 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.
 */

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

#include "peak_canfd_user.h"

/* internal IP core cache size (used as default echo skbs max number) */
#define PCANFD_ECHO_SKB_MAX		24

/* bittiming ranges of the PEAK-System PC CAN-FD interfaces */
static const struct can_bittiming_const peak_canfd_nominal_const = {
	.name = "peak_canfd",
	.tseg1_min = 1,
	.tseg1_max = (1 << PUCAN_TSLOW_TSGEG1_BITS),
	.tseg2_min = 1,
	.tseg2_max = (1 << PUCAN_TSLOW_TSGEG2_BITS),
	.sjw_max = (1 << PUCAN_TSLOW_SJW_BITS),
	.brp_min = 1,
	.brp_max = (1 << PUCAN_TSLOW_BRP_BITS),
	.brp_inc = 1,
};

static const struct can_bittiming_const peak_canfd_data_const = {
	.name = "peak_canfd",
	.tseg1_min = 1,
	.tseg1_max = (1 << PUCAN_TFAST_TSGEG1_BITS),
	.tseg2_min = 1,
	.tseg2_max = (1 << PUCAN_TFAST_TSGEG2_BITS),
	.sjw_max = (1 << PUCAN_TFAST_SJW_BITS),
	.brp_min = 1,
	.brp_max = (1 << PUCAN_TFAST_BRP_BITS),
	.brp_inc = 1,
};

static struct peak_canfd_priv *pucan_init_cmd(struct peak_canfd_priv *priv)
{
	priv->cmd_len = 0;
	return priv;
}

static void *pucan_add_cmd(struct peak_canfd_priv *priv, int cmd_op)
{
	struct pucan_command *cmd;

	if (priv->cmd_len + sizeof(*cmd) > priv->cmd_maxlen)
		return NULL;

	cmd = priv->cmd_buffer + priv->cmd_len;

	/* reset all unused bit to default */
	memset(cmd, 0, sizeof(*cmd));

	cmd->opcode_channel = pucan_cmd_opcode_channel(priv->index, cmd_op);
	priv->cmd_len += sizeof(*cmd);

	return cmd;
}

static int pucan_write_cmd(struct peak_canfd_priv *priv)
{
	int err;

	if (priv->pre_cmd) {
		err = priv->pre_cmd(priv);
		if (err)
			return err;
	}

	err = priv->write_cmd(priv);
	if (err)
		return err;

	if (priv->post_cmd)
		err = priv->post_cmd(priv);

	return err;
}

/* uCAN commands interface functions */
static int pucan_set_reset_mode(struct peak_canfd_priv *priv)
{
	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_RESET_MODE);
	return pucan_write_cmd(priv);
}

static int pucan_set_normal_mode(struct peak_canfd_priv *priv)
{
	int err;

	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_NORMAL_MODE);
	err = pucan_write_cmd(priv);
	if (!err)
		priv->can.state = CAN_STATE_ERROR_ACTIVE;

	return err;
}

static int pucan_set_listen_only_mode(struct peak_canfd_priv *priv)
{
	int err;

	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_LISTEN_ONLY_MODE);
	err = pucan_write_cmd(priv);
	if (!err)
		priv->can.state = CAN_STATE_ERROR_ACTIVE;

	return err;
}

static int pucan_set_timing_slow(struct peak_canfd_priv *priv,
				 const struct can_bittiming *pbt)
{
	struct pucan_timing_slow *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TIMING_SLOW);

	cmd->sjw_t = PUCAN_TSLOW_SJW_T(pbt->sjw - 1,
				priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES);
	cmd->tseg1 = PUCAN_TSLOW_TSEG1(pbt->prop_seg + pbt->phase_seg1 - 1);
	cmd->tseg2 = PUCAN_TSLOW_TSEG2(pbt->phase_seg2 - 1);
	cmd->brp = cpu_to_le16(PUCAN_TSLOW_BRP(pbt->brp - 1));

	cmd->ewl = 96;	/* default */

	netdev_dbg(priv->ndev,
		   "nominal: brp=%u tseg1=%u tseg2=%u sjw=%u\n",
		   le16_to_cpu(cmd->brp), cmd->tseg1, cmd->tseg2, cmd->sjw_t);

	return pucan_write_cmd(priv);
}

static int pucan_set_timing_fast(struct peak_canfd_priv *priv,
				 const struct can_bittiming *pbt)
{
	struct pucan_timing_fast *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TIMING_FAST);

	cmd->sjw = PUCAN_TFAST_SJW(pbt->sjw - 1);
	cmd->tseg1 = PUCAN_TFAST_TSEG1(pbt->prop_seg + pbt->phase_seg1 - 1);
	cmd->tseg2 = PUCAN_TFAST_TSEG2(pbt->phase_seg2 - 1);
	cmd->brp = cpu_to_le16(PUCAN_TFAST_BRP(pbt->brp - 1));

	netdev_dbg(priv->ndev,
		   "data: brp=%u tseg1=%u tseg2=%u sjw=%u\n",
		   le16_to_cpu(cmd->brp), cmd->tseg1, cmd->tseg2, cmd->sjw);

	return pucan_write_cmd(priv);
}

static int pucan_set_std_filter(struct peak_canfd_priv *priv, u8 row, u32 mask)
{
	struct pucan_std_filter *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_SET_STD_FILTER);

	/* all the 11-bits CAN ID values are represented by one bit in a
	 * 64 rows array of 32 bits: the upper 6 bits of the CAN ID select the
	 * row while the lowest 5 bits select the bit in that row.
	 *
	 * bit	filter
	 * 1	passed
	 * 0	discarded
	 */

	/* select the row */
	cmd->idx = row;

	/* set/unset bits in the row */
	cmd->mask = cpu_to_le32(mask);

	return pucan_write_cmd(priv);
}

static int pucan_tx_abort(struct peak_canfd_priv *priv, u16 flags)
{
	struct pucan_tx_abort *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TX_ABORT);

	cmd->flags = cpu_to_le16(flags);

	return pucan_write_cmd(priv);
}

static int pucan_clr_err_counters(struct peak_canfd_priv *priv)
{
	struct pucan_wr_err_cnt *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_WR_ERR_CNT);

	cmd->sel_mask = cpu_to_le16(PUCAN_WRERRCNT_TE | PUCAN_WRERRCNT_RE);
	cmd->tx_counter = 0;
	cmd->rx_counter = 0;

	return pucan_write_cmd(priv);
}

static int pucan_set_options(struct peak_canfd_priv *priv, u16 opt_mask)
{
	struct pucan_options *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_SET_EN_OPTION);

	cmd->options = cpu_to_le16(opt_mask);

	return pucan_write_cmd(priv);
}

static int pucan_clr_options(struct peak_canfd_priv *priv, u16 opt_mask)
{
	struct pucan_options *cmd;

	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_CLR_DIS_OPTION);

	cmd->options = cpu_to_le16(opt_mask);

	return pucan_write_cmd(priv);
}

static int pucan_setup_rx_barrier(struct peak_canfd_priv *priv)
{
	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_RX_BARRIER);

	return pucan_write_cmd(priv);
}

/* handle the reception of one CAN frame */
static int pucan_handle_can_rx(struct peak_canfd_priv *priv,
			       struct pucan_rx_msg *msg)
{
	struct net_device_stats *stats = &priv->ndev->stats;
	struct canfd_frame *cf;
	struct sk_buff *skb;
	const u16 rx_msg_flags = le16_to_cpu(msg->flags);
	u8 cf_len;

	if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN)
		cf_len = can_dlc2len(get_canfd_dlc(pucan_msg_get_dlc(msg)));
	else
		cf_len = get_can_dlc(pucan_msg_get_dlc(msg));

	/* if this frame is an echo, */
	if ((rx_msg_flags & PUCAN_MSG_LOOPED_BACK) &&
	    !(rx_msg_flags & PUCAN_MSG_SELF_RECEIVE)) {
		unsigned long flags;

		spin_lock_irqsave(&priv->echo_lock, flags);
		can_get_echo_skb(priv->ndev, msg->client);

		/* count bytes of the echo instead of skb */
		stats->tx_bytes += cf_len;
		stats->tx_packets++;

		/* restart tx queue (a slot is free) */
		netif_wake_queue(priv->ndev);

		spin_unlock_irqrestore(&priv->echo_lock, flags);
		return 0;
	}

	/* otherwise, it should be pushed into rx fifo */
	if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN) {
		/* CANFD frame case */
		skb = alloc_canfd_skb(priv->ndev, &cf);
		if (!skb)
			return -ENOMEM;

		if (rx_msg_flags & PUCAN_MSG_BITRATE_SWITCH)
			cf->flags |= CANFD_BRS;

		if (rx_msg_flags & PUCAN_MSG_ERROR_STATE_IND)
			cf->flags |= CANFD_ESI;
	} else {
		/* CAN 2.0 frame case */
		skb = alloc_can_skb(priv->ndev, (struct can_frame **)&cf);
		if (!skb)
			return -ENOMEM;
	}

	cf->can_id = le32_to_cpu(msg->can_id);
	cf->len = cf_len;

	if (rx_msg_flags & PUCAN_MSG_EXT_ID)
		cf->can_id |= CAN_EFF_FLAG;

	if (rx_msg_flags & PUCAN_MSG_RTR)
		cf->can_id |= CAN_RTR_FLAG;
	else
		memcpy(cf->data, msg->d, cf->len);

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

	netif_rx(skb);

	return 0;
}

/* handle rx/tx error counters notification */
static int pucan_handle_error(struct peak_canfd_priv *priv,
			      struct pucan_error_msg *msg)
{
	priv->bec.txerr = msg->tx_err_cnt;
	priv->bec.rxerr = msg->rx_err_cnt;

	return 0;
}

/* handle status notification */
static int pucan_handle_status(struct peak_canfd_priv *priv,
			       struct pucan_status_msg *msg)
{
	struct net_device *ndev = priv->ndev;
	struct net_device_stats *stats = &ndev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;

	/* this STATUS is the CNF of the RX_BARRIER: Tx path can be setup */
	if (pucan_status_is_rx_barrier(msg)) {

		if (priv->enable_tx_path) {
			int err = priv->enable_tx_path(priv);

			if (err)
				return err;
		}

		/* start network queue (echo_skb array is empty) */
		netif_start_queue(ndev);

		return 0;
	}

	skb = alloc_can_err_skb(ndev, &cf);

	/* test state error bits according to their priority */
	if (pucan_status_is_busoff(msg)) {
		netdev_dbg(ndev, "Bus-off entry status\n");
		priv->can.state = CAN_STATE_BUS_OFF;
		priv->can.can_stats.bus_off++;
		can_bus_off(ndev);
		if (skb)
			cf->can_id |= CAN_ERR_BUSOFF;

	} else if (pucan_status_is_passive(msg)) {
		netdev_dbg(ndev, "Error passive status\n");
		priv->can.state = CAN_STATE_ERROR_PASSIVE;
		priv->can.can_stats.error_passive++;
		if (skb) {
			cf->can_id |= CAN_ERR_CRTL;
			cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
					CAN_ERR_CRTL_TX_PASSIVE :
					CAN_ERR_CRTL_RX_PASSIVE;
			cf->data[6] = priv->bec.txerr;
			cf->data[7] = priv->bec.rxerr;
		}

	} else if (pucan_status_is_warning(msg)) {
		netdev_dbg(ndev, "Error warning status\n");
		priv->can.state = CAN_STATE_ERROR_WARNING;
		priv->can.can_stats.error_warning++;
		if (skb) {
			cf->can_id |= CAN_ERR_CRTL;
			cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
					CAN_ERR_CRTL_TX_WARNING :
					CAN_ERR_CRTL_RX_WARNING;
			cf->data[6] = priv->bec.txerr;
			cf->data[7] = priv->bec.rxerr;
		}

	} else if (priv->can.state != CAN_STATE_ERROR_ACTIVE) {
		/* back to ERROR_ACTIVE */
		netdev_dbg(ndev, "Error active status\n");
		can_change_state(ndev, cf, CAN_STATE_ERROR_ACTIVE,
				 CAN_STATE_ERROR_ACTIVE);
	} else {
		dev_kfree_skb(skb);
		return 0;
	}

	if (!skb) {
		stats->rx_dropped++;
		return -ENOMEM;
	}

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

	return 0;
}

/* handle uCAN Rx overflow notification */
static int pucan_handle_cache_critical(struct peak_canfd_priv *priv)
{
	struct net_device_stats *stats = &priv->ndev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;

	stats->rx_over_errors++;
	stats->rx_errors++;

	skb = alloc_can_err_skb(priv->ndev, &cf);
	if (!skb) {
		stats->rx_dropped++;
		return -ENOMEM;
	}

	cf->can_id |= CAN_ERR_CRTL;
	cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;

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

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

	return 0;
}

/* handle a single uCAN message */
int peak_canfd_handle_msg(struct peak_canfd_priv *priv,
			  struct pucan_rx_msg *msg)
{
	u16 msg_type = le16_to_cpu(msg->type);
	int msg_size = le16_to_cpu(msg->size);
	int err;

	if (!msg_size || !msg_type) {
		/* null packet found: end of list */
		goto exit;
	}

	switch (msg_type) {
	case PUCAN_MSG_CAN_RX:
		err = pucan_handle_can_rx(priv, (struct pucan_rx_msg *)msg);
		break;
	case PUCAN_MSG_ERROR:
		err = pucan_handle_error(priv, (struct pucan_error_msg *)msg);
		break;
	case PUCAN_MSG_STATUS:
		err = pucan_handle_status(priv, (struct pucan_status_msg *)msg);
		break;
	case PUCAN_MSG_CACHE_CRITICAL:
		err = pucan_handle_cache_critical(priv);
		break;
	default:
		err = 0;
	}

	if (err < 0)
		return err;

exit:
	return msg_size;
}

/* handle a list of rx_count messages from rx_msg memory address */
int peak_canfd_handle_msgs_list(struct peak_canfd_priv *priv,
				struct pucan_rx_msg *msg_list, int msg_count)
{
	void *msg_ptr = msg_list;
	int i, msg_size = 0;

	for (i = 0; i < msg_count; i++) {
		msg_size = peak_canfd_handle_msg(priv, msg_ptr);

		/* a null packet can be found at the end of a list */
		if (msg_size <= 0)
			break;

		msg_ptr += ALIGN(msg_size, 4);
	}

	if (msg_size < 0)
		return msg_size;

	return i;
}

static int peak_canfd_start(struct peak_canfd_priv *priv)
{
	int err;

	err = pucan_clr_err_counters(priv);
	if (err)
		goto err_exit;

	priv->echo_idx = 0;

	priv->bec.txerr = 0;
	priv->bec.rxerr = 0;

	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
		err = pucan_set_listen_only_mode(priv);
	else
		err = pucan_set_normal_mode(priv);

err_exit:
	return err;
}

static void peak_canfd_stop(struct peak_canfd_priv *priv)
{
	int err;

	/* go back to RESET mode */
	err = pucan_set_reset_mode(priv);
	if (err) {
		netdev_err(priv->ndev, "channel %u reset failed\n",
			   priv->index);
	} else {
		/* abort last Tx (MUST be done in RESET mode only!) */
		pucan_tx_abort(priv, PUCAN_TX_ABORT_FLUSH);
	}
}

static int peak_canfd_set_mode(struct net_device *ndev, enum can_mode mode)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);

	switch (mode) {
	case CAN_MODE_START:
		peak_canfd_start(priv);
		netif_wake_queue(ndev);
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int peak_canfd_get_berr_counter(const struct net_device *ndev,
				       struct can_berr_counter *bec)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);

	*bec = priv->bec;
	return 0;
}

static int peak_canfd_open(struct net_device *ndev)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);
	int i, err = 0;

	err = open_candev(ndev);
	if (err) {
		netdev_err(ndev, "open_candev() failed, error %d\n", err);
		goto err_exit;
	}

	err = pucan_set_reset_mode(priv);
	if (err)
		goto err_close;

	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
		if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
			err = pucan_clr_options(priv, PUCAN_OPTION_CANDFDISO);
		else
			err = pucan_set_options(priv, PUCAN_OPTION_CANDFDISO);

		if (err)
			goto err_close;
	}

	/* set option: get rx/tx error counters */
	err = pucan_set_options(priv, PUCAN_OPTION_ERROR);
	if (err)
		goto err_close;

	/* accept all standard CAN ID */
	for (i = 0; i <= PUCAN_FLTSTD_ROW_IDX_MAX; i++)
		pucan_set_std_filter(priv, i, 0xffffffff);

	err = peak_canfd_start(priv);
	if (err)
		goto err_close;

	/* receiving the RB status says when Tx path is ready */
	err = pucan_setup_rx_barrier(priv);
	if (!err)
		goto err_exit;

err_close:
	close_candev(ndev);
err_exit:
	return err;
}

static int peak_canfd_set_bittiming(struct net_device *ndev)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);

	return pucan_set_timing_slow(priv, &priv->can.bittiming);
}

static int peak_canfd_set_data_bittiming(struct net_device *ndev)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);

	return pucan_set_timing_fast(priv, &priv->can.data_bittiming);
}

static int peak_canfd_close(struct net_device *ndev)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);

	netif_stop_queue(ndev);
	peak_canfd_stop(priv);
	close_candev(ndev);

	return 0;
}

static netdev_tx_t peak_canfd_start_xmit(struct sk_buff *skb,
					 struct net_device *ndev)
{
	struct peak_canfd_priv *priv = netdev_priv(ndev);
	struct net_device_stats *stats = &ndev->stats;
	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
	struct pucan_tx_msg *msg;
	u16 msg_size, msg_flags;
	unsigned long flags;
	bool should_stop_tx_queue;
	int room_left;
	u8 can_dlc;

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

	msg_size = ALIGN(sizeof(*msg) + cf->len, 4);
	msg = priv->alloc_tx_msg(priv, msg_size, &room_left);

	/* should never happen except under bus-off condition and (auto-)restart
	 * mechanism
	 */
	if (!msg) {
		stats->tx_dropped++;
		netif_stop_queue(ndev);
		return NETDEV_TX_BUSY;
	}

	msg->size = cpu_to_le16(msg_size);
	msg->type = cpu_to_le16(PUCAN_MSG_CAN_TX);
	msg_flags = 0;

	if (cf->can_id & CAN_EFF_FLAG) {
		msg_flags |= PUCAN_MSG_EXT_ID;
		msg->can_id = cpu_to_le32(cf->can_id & CAN_EFF_MASK);
	} else {
		msg->can_id = cpu_to_le32(cf->can_id & CAN_SFF_MASK);
	}

	if (can_is_canfd_skb(skb)) {
		/* CAN FD frame format */
		can_dlc = can_len2dlc(cf->len);

		msg_flags |= PUCAN_MSG_EXT_DATA_LEN;

		if (cf->flags & CANFD_BRS)
			msg_flags |= PUCAN_MSG_BITRATE_SWITCH;

		if (cf->flags & CANFD_ESI)
			msg_flags |= PUCAN_MSG_ERROR_STATE_IND;
	} else {
		/* CAN 2.0 frame format */
		can_dlc = cf->len;

		if (cf->can_id & CAN_RTR_FLAG)
			msg_flags |= PUCAN_MSG_RTR;
	}

	/* always ask loopback for echo management */
	msg_flags |= PUCAN_MSG_LOOPED_BACK;

	/* set driver specific bit to differentiate with application loopback */
	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
		msg_flags |= PUCAN_MSG_SELF_RECEIVE;

	msg->flags = cpu_to_le16(msg_flags);
	msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(priv->index, can_dlc);
	memcpy(msg->d, cf->data, cf->len);

	/* struct msg client field is used as an index in the echo skbs ring */
	msg->client = priv->echo_idx;

	spin_lock_irqsave(&priv->echo_lock, flags);

	/* prepare and save echo skb in internal slot */
	can_put_echo_skb(skb, ndev, priv->echo_idx);

	/* move echo index to the next slot */
	priv->echo_idx = (priv->echo_idx + 1) % priv->can.echo_skb_max;

	/* if next slot is not free, stop network queue (no slot free in echo
	 * skb ring means that the controller did not write these frames on
	 * the bus: no need to continue).
	 */
	should_stop_tx_queue = !!(priv->can.echo_skb[priv->echo_idx]);

	/* stop network tx queue if not enough room to save one more msg too */
	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
		should_stop_tx_queue |= (room_left <
					(sizeof(*msg) + CANFD_MAX_DLEN));
	else
		should_stop_tx_queue |= (room_left <
					(sizeof(*msg) + CAN_MAX_DLEN));

	if (should_stop_tx_queue)
		netif_stop_queue(ndev);

	spin_unlock_irqrestore(&priv->echo_lock, flags);

	/* write the skb on the interface */
	priv->write_tx_msg(priv, msg);

	return NETDEV_TX_OK;
}

static const struct net_device_ops peak_canfd_netdev_ops = {
	.ndo_open = peak_canfd_open,
	.ndo_stop = peak_canfd_close,
	.ndo_start_xmit = peak_canfd_start_xmit,
	.ndo_change_mtu = can_change_mtu,
};

struct net_device *alloc_peak_canfd_dev(int sizeof_priv, int index,
					int echo_skb_max)
{
	struct net_device *ndev;
	struct peak_canfd_priv *priv;

	/* we DO support local echo */
	if (echo_skb_max < 0)
		echo_skb_max = PCANFD_ECHO_SKB_MAX;

	/* allocate the candev object */
	ndev = alloc_candev(sizeof_priv, echo_skb_max);
	if (!ndev)
		return NULL;

	priv = netdev_priv(ndev);

	/* complete now socket-can initialization side */
	priv->can.state = CAN_STATE_STOPPED;
	priv->can.bittiming_const = &peak_canfd_nominal_const;
	priv->can.data_bittiming_const = &peak_canfd_data_const;

	priv->can.do_set_mode = peak_canfd_set_mode;
	priv->can.do_get_berr_counter = peak_canfd_get_berr_counter;
	priv->can.do_set_bittiming = peak_canfd_set_bittiming;
	priv->can.do_set_data_bittiming = peak_canfd_set_data_bittiming;
	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
				       CAN_CTRLMODE_LISTENONLY |
				       CAN_CTRLMODE_3_SAMPLES |
				       CAN_CTRLMODE_FD |
				       CAN_CTRLMODE_FD_NON_ISO |
				       CAN_CTRLMODE_BERR_REPORTING;

	priv->ndev = ndev;
	priv->index = index;
	priv->cmd_len = 0;
	spin_lock_init(&priv->echo_lock);

	ndev->flags |= IFF_ECHO;
	ndev->netdev_ops = &peak_canfd_netdev_ops;
	ndev->dev_id = index;

	return ndev;
}