1 /*
2  * Copyright (C) 2007, 2011 Wolfgang Grandegger <wg@grandegger.com>
3  * Copyright (C) 2012 Stephane Grosjean <s.grosjean@peak-system.com>
4  *
5  * Copyright (C) 2016  PEAK System-Technik GmbH
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the version 2 of the GNU General Public License
9  * as published by the Free Software Foundation
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  */
16 
17 #include <linux/can.h>
18 #include <linux/can/dev.h>
19 
20 #include "peak_canfd_user.h"
21 
22 /* internal IP core cache size (used as default echo skbs max number) */
23 #define PCANFD_ECHO_SKB_MAX		24
24 
25 /* bittiming ranges of the PEAK-System PC CAN-FD interfaces */
26 static const struct can_bittiming_const peak_canfd_nominal_const = {
27 	.name = "peak_canfd",
28 	.tseg1_min = 1,
29 	.tseg1_max = (1 << PUCAN_TSLOW_TSGEG1_BITS),
30 	.tseg2_min = 1,
31 	.tseg2_max = (1 << PUCAN_TSLOW_TSGEG2_BITS),
32 	.sjw_max = (1 << PUCAN_TSLOW_SJW_BITS),
33 	.brp_min = 1,
34 	.brp_max = (1 << PUCAN_TSLOW_BRP_BITS),
35 	.brp_inc = 1,
36 };
37 
38 static const struct can_bittiming_const peak_canfd_data_const = {
39 	.name = "peak_canfd",
40 	.tseg1_min = 1,
41 	.tseg1_max = (1 << PUCAN_TFAST_TSGEG1_BITS),
42 	.tseg2_min = 1,
43 	.tseg2_max = (1 << PUCAN_TFAST_TSGEG2_BITS),
44 	.sjw_max = (1 << PUCAN_TFAST_SJW_BITS),
45 	.brp_min = 1,
46 	.brp_max = (1 << PUCAN_TFAST_BRP_BITS),
47 	.brp_inc = 1,
48 };
49 
50 static struct peak_canfd_priv *pucan_init_cmd(struct peak_canfd_priv *priv)
51 {
52 	priv->cmd_len = 0;
53 	return priv;
54 }
55 
56 static void *pucan_add_cmd(struct peak_canfd_priv *priv, int cmd_op)
57 {
58 	struct pucan_command *cmd;
59 
60 	if (priv->cmd_len + sizeof(*cmd) > priv->cmd_maxlen)
61 		return NULL;
62 
63 	cmd = priv->cmd_buffer + priv->cmd_len;
64 
65 	/* reset all unused bit to default */
66 	memset(cmd, 0, sizeof(*cmd));
67 
68 	cmd->opcode_channel = pucan_cmd_opcode_channel(priv->index, cmd_op);
69 	priv->cmd_len += sizeof(*cmd);
70 
71 	return cmd;
72 }
73 
74 static int pucan_write_cmd(struct peak_canfd_priv *priv)
75 {
76 	int err;
77 
78 	if (priv->pre_cmd) {
79 		err = priv->pre_cmd(priv);
80 		if (err)
81 			return err;
82 	}
83 
84 	err = priv->write_cmd(priv);
85 	if (err)
86 		return err;
87 
88 	if (priv->post_cmd)
89 		err = priv->post_cmd(priv);
90 
91 	return err;
92 }
93 
94 /* uCAN commands interface functions */
95 static int pucan_set_reset_mode(struct peak_canfd_priv *priv)
96 {
97 	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_RESET_MODE);
98 	return pucan_write_cmd(priv);
99 }
100 
101 static int pucan_set_normal_mode(struct peak_canfd_priv *priv)
102 {
103 	int err;
104 
105 	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_NORMAL_MODE);
106 	err = pucan_write_cmd(priv);
107 	if (!err)
108 		priv->can.state = CAN_STATE_ERROR_ACTIVE;
109 
110 	return err;
111 }
112 
113 static int pucan_set_listen_only_mode(struct peak_canfd_priv *priv)
114 {
115 	int err;
116 
117 	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_LISTEN_ONLY_MODE);
118 	err = pucan_write_cmd(priv);
119 	if (!err)
120 		priv->can.state = CAN_STATE_ERROR_ACTIVE;
121 
122 	return err;
123 }
124 
125 static int pucan_set_timing_slow(struct peak_canfd_priv *priv,
126 				 const struct can_bittiming *pbt)
127 {
128 	struct pucan_timing_slow *cmd;
129 
130 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TIMING_SLOW);
131 
132 	cmd->sjw_t = PUCAN_TSLOW_SJW_T(pbt->sjw - 1,
133 				priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES);
134 	cmd->tseg1 = PUCAN_TSLOW_TSEG1(pbt->prop_seg + pbt->phase_seg1 - 1);
135 	cmd->tseg2 = PUCAN_TSLOW_TSEG2(pbt->phase_seg2 - 1);
136 	cmd->brp = cpu_to_le16(PUCAN_TSLOW_BRP(pbt->brp - 1));
137 
138 	cmd->ewl = 96;	/* default */
139 
140 	netdev_dbg(priv->ndev,
141 		   "nominal: brp=%u tseg1=%u tseg2=%u sjw=%u\n",
142 		   le16_to_cpu(cmd->brp), cmd->tseg1, cmd->tseg2, cmd->sjw_t);
143 
144 	return pucan_write_cmd(priv);
145 }
146 
147 static int pucan_set_timing_fast(struct peak_canfd_priv *priv,
148 				 const struct can_bittiming *pbt)
149 {
150 	struct pucan_timing_fast *cmd;
151 
152 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TIMING_FAST);
153 
154 	cmd->sjw = PUCAN_TFAST_SJW(pbt->sjw - 1);
155 	cmd->tseg1 = PUCAN_TFAST_TSEG1(pbt->prop_seg + pbt->phase_seg1 - 1);
156 	cmd->tseg2 = PUCAN_TFAST_TSEG2(pbt->phase_seg2 - 1);
157 	cmd->brp = cpu_to_le16(PUCAN_TFAST_BRP(pbt->brp - 1));
158 
159 	netdev_dbg(priv->ndev,
160 		   "data: brp=%u tseg1=%u tseg2=%u sjw=%u\n",
161 		   le16_to_cpu(cmd->brp), cmd->tseg1, cmd->tseg2, cmd->sjw);
162 
163 	return pucan_write_cmd(priv);
164 }
165 
166 static int pucan_set_std_filter(struct peak_canfd_priv *priv, u8 row, u32 mask)
167 {
168 	struct pucan_std_filter *cmd;
169 
170 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_SET_STD_FILTER);
171 
172 	/* all the 11-bits CAN ID values are represented by one bit in a
173 	 * 64 rows array of 32 bits: the upper 6 bits of the CAN ID select the
174 	 * row while the lowest 5 bits select the bit in that row.
175 	 *
176 	 * bit	filter
177 	 * 1	passed
178 	 * 0	discarded
179 	 */
180 
181 	/* select the row */
182 	cmd->idx = row;
183 
184 	/* set/unset bits in the row */
185 	cmd->mask = cpu_to_le32(mask);
186 
187 	return pucan_write_cmd(priv);
188 }
189 
190 static int pucan_tx_abort(struct peak_canfd_priv *priv, u16 flags)
191 {
192 	struct pucan_tx_abort *cmd;
193 
194 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_TX_ABORT);
195 
196 	cmd->flags = cpu_to_le16(flags);
197 
198 	return pucan_write_cmd(priv);
199 }
200 
201 static int pucan_clr_err_counters(struct peak_canfd_priv *priv)
202 {
203 	struct pucan_wr_err_cnt *cmd;
204 
205 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_WR_ERR_CNT);
206 
207 	cmd->sel_mask = cpu_to_le16(PUCAN_WRERRCNT_TE | PUCAN_WRERRCNT_RE);
208 	cmd->tx_counter = 0;
209 	cmd->rx_counter = 0;
210 
211 	return pucan_write_cmd(priv);
212 }
213 
214 static int pucan_set_options(struct peak_canfd_priv *priv, u16 opt_mask)
215 {
216 	struct pucan_options *cmd;
217 
218 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_SET_EN_OPTION);
219 
220 	cmd->options = cpu_to_le16(opt_mask);
221 
222 	return pucan_write_cmd(priv);
223 }
224 
225 static int pucan_clr_options(struct peak_canfd_priv *priv, u16 opt_mask)
226 {
227 	struct pucan_options *cmd;
228 
229 	cmd = pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_CLR_DIS_OPTION);
230 
231 	cmd->options = cpu_to_le16(opt_mask);
232 
233 	return pucan_write_cmd(priv);
234 }
235 
236 static int pucan_setup_rx_barrier(struct peak_canfd_priv *priv)
237 {
238 	pucan_add_cmd(pucan_init_cmd(priv), PUCAN_CMD_RX_BARRIER);
239 
240 	return pucan_write_cmd(priv);
241 }
242 
243 /* handle the reception of one CAN frame */
244 static int pucan_handle_can_rx(struct peak_canfd_priv *priv,
245 			       struct pucan_rx_msg *msg)
246 {
247 	struct net_device_stats *stats = &priv->ndev->stats;
248 	struct canfd_frame *cf;
249 	struct sk_buff *skb;
250 	const u16 rx_msg_flags = le16_to_cpu(msg->flags);
251 	u8 cf_len;
252 
253 	if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN)
254 		cf_len = can_dlc2len(get_canfd_dlc(pucan_msg_get_dlc(msg)));
255 	else
256 		cf_len = get_can_dlc(pucan_msg_get_dlc(msg));
257 
258 	/* if this frame is an echo, */
259 	if ((rx_msg_flags & PUCAN_MSG_LOOPED_BACK) &&
260 	    !(rx_msg_flags & PUCAN_MSG_SELF_RECEIVE)) {
261 		unsigned long flags;
262 
263 		spin_lock_irqsave(&priv->echo_lock, flags);
264 		can_get_echo_skb(priv->ndev, msg->client);
265 
266 		/* count bytes of the echo instead of skb */
267 		stats->tx_bytes += cf_len;
268 		stats->tx_packets++;
269 
270 		/* restart tx queue (a slot is free) */
271 		netif_wake_queue(priv->ndev);
272 
273 		spin_unlock_irqrestore(&priv->echo_lock, flags);
274 		return 0;
275 	}
276 
277 	/* otherwise, it should be pushed into rx fifo */
278 	if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN) {
279 		/* CANFD frame case */
280 		skb = alloc_canfd_skb(priv->ndev, &cf);
281 		if (!skb)
282 			return -ENOMEM;
283 
284 		if (rx_msg_flags & PUCAN_MSG_BITRATE_SWITCH)
285 			cf->flags |= CANFD_BRS;
286 
287 		if (rx_msg_flags & PUCAN_MSG_ERROR_STATE_IND)
288 			cf->flags |= CANFD_ESI;
289 	} else {
290 		/* CAN 2.0 frame case */
291 		skb = alloc_can_skb(priv->ndev, (struct can_frame **)&cf);
292 		if (!skb)
293 			return -ENOMEM;
294 	}
295 
296 	cf->can_id = le32_to_cpu(msg->can_id);
297 	cf->len = cf_len;
298 
299 	if (rx_msg_flags & PUCAN_MSG_EXT_ID)
300 		cf->can_id |= CAN_EFF_FLAG;
301 
302 	if (rx_msg_flags & PUCAN_MSG_RTR)
303 		cf->can_id |= CAN_RTR_FLAG;
304 	else
305 		memcpy(cf->data, msg->d, cf->len);
306 
307 	stats->rx_bytes += cf->len;
308 	stats->rx_packets++;
309 
310 	netif_rx(skb);
311 
312 	return 0;
313 }
314 
315 /* handle rx/tx error counters notification */
316 static int pucan_handle_error(struct peak_canfd_priv *priv,
317 			      struct pucan_error_msg *msg)
318 {
319 	priv->bec.txerr = msg->tx_err_cnt;
320 	priv->bec.rxerr = msg->rx_err_cnt;
321 
322 	return 0;
323 }
324 
325 /* handle status notification */
326 static int pucan_handle_status(struct peak_canfd_priv *priv,
327 			       struct pucan_status_msg *msg)
328 {
329 	struct net_device *ndev = priv->ndev;
330 	struct net_device_stats *stats = &ndev->stats;
331 	struct can_frame *cf;
332 	struct sk_buff *skb;
333 
334 	/* this STATUS is the CNF of the RX_BARRIER: Tx path can be setup */
335 	if (pucan_status_is_rx_barrier(msg)) {
336 
337 		if (priv->enable_tx_path) {
338 			int err = priv->enable_tx_path(priv);
339 
340 			if (err)
341 				return err;
342 		}
343 
344 		/* start network queue (echo_skb array is empty) */
345 		netif_start_queue(ndev);
346 
347 		return 0;
348 	}
349 
350 	skb = alloc_can_err_skb(ndev, &cf);
351 
352 	/* test state error bits according to their priority */
353 	if (pucan_status_is_busoff(msg)) {
354 		netdev_dbg(ndev, "Bus-off entry status\n");
355 		priv->can.state = CAN_STATE_BUS_OFF;
356 		priv->can.can_stats.bus_off++;
357 		can_bus_off(ndev);
358 		if (skb)
359 			cf->can_id |= CAN_ERR_BUSOFF;
360 
361 	} else if (pucan_status_is_passive(msg)) {
362 		netdev_dbg(ndev, "Error passive status\n");
363 		priv->can.state = CAN_STATE_ERROR_PASSIVE;
364 		priv->can.can_stats.error_passive++;
365 		if (skb) {
366 			cf->can_id |= CAN_ERR_CRTL;
367 			cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
368 					CAN_ERR_CRTL_TX_PASSIVE :
369 					CAN_ERR_CRTL_RX_PASSIVE;
370 			cf->data[6] = priv->bec.txerr;
371 			cf->data[7] = priv->bec.rxerr;
372 		}
373 
374 	} else if (pucan_status_is_warning(msg)) {
375 		netdev_dbg(ndev, "Error warning status\n");
376 		priv->can.state = CAN_STATE_ERROR_WARNING;
377 		priv->can.can_stats.error_warning++;
378 		if (skb) {
379 			cf->can_id |= CAN_ERR_CRTL;
380 			cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
381 					CAN_ERR_CRTL_TX_WARNING :
382 					CAN_ERR_CRTL_RX_WARNING;
383 			cf->data[6] = priv->bec.txerr;
384 			cf->data[7] = priv->bec.rxerr;
385 		}
386 
387 	} else if (priv->can.state != CAN_STATE_ERROR_ACTIVE) {
388 		/* back to ERROR_ACTIVE */
389 		netdev_dbg(ndev, "Error active status\n");
390 		can_change_state(ndev, cf, CAN_STATE_ERROR_ACTIVE,
391 				 CAN_STATE_ERROR_ACTIVE);
392 	} else {
393 		dev_kfree_skb(skb);
394 		return 0;
395 	}
396 
397 	if (!skb) {
398 		stats->rx_dropped++;
399 		return -ENOMEM;
400 	}
401 
402 	stats->rx_packets++;
403 	stats->rx_bytes += cf->can_dlc;
404 	netif_rx(skb);
405 
406 	return 0;
407 }
408 
409 /* handle uCAN Rx overflow notification */
410 static int pucan_handle_cache_critical(struct peak_canfd_priv *priv)
411 {
412 	struct net_device_stats *stats = &priv->ndev->stats;
413 	struct can_frame *cf;
414 	struct sk_buff *skb;
415 
416 	stats->rx_over_errors++;
417 	stats->rx_errors++;
418 
419 	skb = alloc_can_err_skb(priv->ndev, &cf);
420 	if (!skb) {
421 		stats->rx_dropped++;
422 		return -ENOMEM;
423 	}
424 
425 	cf->can_id |= CAN_ERR_CRTL;
426 	cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
427 
428 	cf->data[6] = priv->bec.txerr;
429 	cf->data[7] = priv->bec.rxerr;
430 
431 	stats->rx_bytes += cf->can_dlc;
432 	stats->rx_packets++;
433 	netif_rx(skb);
434 
435 	return 0;
436 }
437 
438 /* handle a single uCAN message */
439 int peak_canfd_handle_msg(struct peak_canfd_priv *priv,
440 			  struct pucan_rx_msg *msg)
441 {
442 	u16 msg_type = le16_to_cpu(msg->type);
443 	int msg_size = le16_to_cpu(msg->size);
444 	int err;
445 
446 	if (!msg_size || !msg_type) {
447 		/* null packet found: end of list */
448 		goto exit;
449 	}
450 
451 	switch (msg_type) {
452 	case PUCAN_MSG_CAN_RX:
453 		err = pucan_handle_can_rx(priv, (struct pucan_rx_msg *)msg);
454 		break;
455 	case PUCAN_MSG_ERROR:
456 		err = pucan_handle_error(priv, (struct pucan_error_msg *)msg);
457 		break;
458 	case PUCAN_MSG_STATUS:
459 		err = pucan_handle_status(priv, (struct pucan_status_msg *)msg);
460 		break;
461 	case PUCAN_MSG_CACHE_CRITICAL:
462 		err = pucan_handle_cache_critical(priv);
463 		break;
464 	default:
465 		err = 0;
466 	}
467 
468 	if (err < 0)
469 		return err;
470 
471 exit:
472 	return msg_size;
473 }
474 
475 /* handle a list of rx_count messages from rx_msg memory address */
476 int peak_canfd_handle_msgs_list(struct peak_canfd_priv *priv,
477 				struct pucan_rx_msg *msg_list, int msg_count)
478 {
479 	void *msg_ptr = msg_list;
480 	int i, msg_size = 0;
481 
482 	for (i = 0; i < msg_count; i++) {
483 		msg_size = peak_canfd_handle_msg(priv, msg_ptr);
484 
485 		/* a null packet can be found at the end of a list */
486 		if (msg_size <= 0)
487 			break;
488 
489 		msg_ptr += ALIGN(msg_size, 4);
490 	}
491 
492 	if (msg_size < 0)
493 		return msg_size;
494 
495 	return i;
496 }
497 
498 static int peak_canfd_start(struct peak_canfd_priv *priv)
499 {
500 	int err;
501 
502 	err = pucan_clr_err_counters(priv);
503 	if (err)
504 		goto err_exit;
505 
506 	priv->echo_idx = 0;
507 
508 	priv->bec.txerr = 0;
509 	priv->bec.rxerr = 0;
510 
511 	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
512 		err = pucan_set_listen_only_mode(priv);
513 	else
514 		err = pucan_set_normal_mode(priv);
515 
516 err_exit:
517 	return err;
518 }
519 
520 static void peak_canfd_stop(struct peak_canfd_priv *priv)
521 {
522 	int err;
523 
524 	/* go back to RESET mode */
525 	err = pucan_set_reset_mode(priv);
526 	if (err) {
527 		netdev_err(priv->ndev, "channel %u reset failed\n",
528 			   priv->index);
529 	} else {
530 		/* abort last Tx (MUST be done in RESET mode only!) */
531 		pucan_tx_abort(priv, PUCAN_TX_ABORT_FLUSH);
532 	}
533 }
534 
535 static int peak_canfd_set_mode(struct net_device *ndev, enum can_mode mode)
536 {
537 	struct peak_canfd_priv *priv = netdev_priv(ndev);
538 
539 	switch (mode) {
540 	case CAN_MODE_START:
541 		peak_canfd_start(priv);
542 		netif_wake_queue(ndev);
543 		break;
544 	default:
545 		return -EOPNOTSUPP;
546 	}
547 
548 	return 0;
549 }
550 
551 static int peak_canfd_get_berr_counter(const struct net_device *ndev,
552 				       struct can_berr_counter *bec)
553 {
554 	struct peak_canfd_priv *priv = netdev_priv(ndev);
555 
556 	*bec = priv->bec;
557 	return 0;
558 }
559 
560 static int peak_canfd_open(struct net_device *ndev)
561 {
562 	struct peak_canfd_priv *priv = netdev_priv(ndev);
563 	int i, err = 0;
564 
565 	err = open_candev(ndev);
566 	if (err) {
567 		netdev_err(ndev, "open_candev() failed, error %d\n", err);
568 		goto err_exit;
569 	}
570 
571 	err = pucan_set_reset_mode(priv);
572 	if (err)
573 		goto err_close;
574 
575 	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
576 		if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
577 			err = pucan_clr_options(priv, PUCAN_OPTION_CANDFDISO);
578 		else
579 			err = pucan_set_options(priv, PUCAN_OPTION_CANDFDISO);
580 
581 		if (err)
582 			goto err_close;
583 	}
584 
585 	/* set option: get rx/tx error counters */
586 	err = pucan_set_options(priv, PUCAN_OPTION_ERROR);
587 	if (err)
588 		goto err_close;
589 
590 	/* accept all standard CAN ID */
591 	for (i = 0; i <= PUCAN_FLTSTD_ROW_IDX_MAX; i++)
592 		pucan_set_std_filter(priv, i, 0xffffffff);
593 
594 	err = peak_canfd_start(priv);
595 	if (err)
596 		goto err_close;
597 
598 	/* receiving the RB status says when Tx path is ready */
599 	err = pucan_setup_rx_barrier(priv);
600 	if (!err)
601 		goto err_exit;
602 
603 err_close:
604 	close_candev(ndev);
605 err_exit:
606 	return err;
607 }
608 
609 static int peak_canfd_set_bittiming(struct net_device *ndev)
610 {
611 	struct peak_canfd_priv *priv = netdev_priv(ndev);
612 
613 	return pucan_set_timing_slow(priv, &priv->can.bittiming);
614 }
615 
616 static int peak_canfd_set_data_bittiming(struct net_device *ndev)
617 {
618 	struct peak_canfd_priv *priv = netdev_priv(ndev);
619 
620 	return pucan_set_timing_fast(priv, &priv->can.data_bittiming);
621 }
622 
623 static int peak_canfd_close(struct net_device *ndev)
624 {
625 	struct peak_canfd_priv *priv = netdev_priv(ndev);
626 
627 	netif_stop_queue(ndev);
628 	peak_canfd_stop(priv);
629 	close_candev(ndev);
630 
631 	return 0;
632 }
633 
634 static netdev_tx_t peak_canfd_start_xmit(struct sk_buff *skb,
635 					 struct net_device *ndev)
636 {
637 	struct peak_canfd_priv *priv = netdev_priv(ndev);
638 	struct net_device_stats *stats = &ndev->stats;
639 	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
640 	struct pucan_tx_msg *msg;
641 	u16 msg_size, msg_flags;
642 	unsigned long flags;
643 	bool should_stop_tx_queue;
644 	int room_left;
645 	u8 can_dlc;
646 
647 	if (can_dropped_invalid_skb(ndev, skb))
648 		return NETDEV_TX_OK;
649 
650 	msg_size = ALIGN(sizeof(*msg) + cf->len, 4);
651 	msg = priv->alloc_tx_msg(priv, msg_size, &room_left);
652 
653 	/* should never happen except under bus-off condition and (auto-)restart
654 	 * mechanism
655 	 */
656 	if (!msg) {
657 		stats->tx_dropped++;
658 		netif_stop_queue(ndev);
659 		return NETDEV_TX_BUSY;
660 	}
661 
662 	msg->size = cpu_to_le16(msg_size);
663 	msg->type = cpu_to_le16(PUCAN_MSG_CAN_TX);
664 	msg_flags = 0;
665 
666 	if (cf->can_id & CAN_EFF_FLAG) {
667 		msg_flags |= PUCAN_MSG_EXT_ID;
668 		msg->can_id = cpu_to_le32(cf->can_id & CAN_EFF_MASK);
669 	} else {
670 		msg->can_id = cpu_to_le32(cf->can_id & CAN_SFF_MASK);
671 	}
672 
673 	if (can_is_canfd_skb(skb)) {
674 		/* CAN FD frame format */
675 		can_dlc = can_len2dlc(cf->len);
676 
677 		msg_flags |= PUCAN_MSG_EXT_DATA_LEN;
678 
679 		if (cf->flags & CANFD_BRS)
680 			msg_flags |= PUCAN_MSG_BITRATE_SWITCH;
681 
682 		if (cf->flags & CANFD_ESI)
683 			msg_flags |= PUCAN_MSG_ERROR_STATE_IND;
684 	} else {
685 		/* CAN 2.0 frame format */
686 		can_dlc = cf->len;
687 
688 		if (cf->can_id & CAN_RTR_FLAG)
689 			msg_flags |= PUCAN_MSG_RTR;
690 	}
691 
692 	/* always ask loopback for echo management */
693 	msg_flags |= PUCAN_MSG_LOOPED_BACK;
694 
695 	/* set driver specific bit to differentiate with application loopback */
696 	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
697 		msg_flags |= PUCAN_MSG_SELF_RECEIVE;
698 
699 	msg->flags = cpu_to_le16(msg_flags);
700 	msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(priv->index, can_dlc);
701 	memcpy(msg->d, cf->data, cf->len);
702 
703 	/* struct msg client field is used as an index in the echo skbs ring */
704 	msg->client = priv->echo_idx;
705 
706 	spin_lock_irqsave(&priv->echo_lock, flags);
707 
708 	/* prepare and save echo skb in internal slot */
709 	can_put_echo_skb(skb, ndev, priv->echo_idx);
710 
711 	/* move echo index to the next slot */
712 	priv->echo_idx = (priv->echo_idx + 1) % priv->can.echo_skb_max;
713 
714 	/* if next slot is not free, stop network queue (no slot free in echo
715 	 * skb ring means that the controller did not write these frames on
716 	 * the bus: no need to continue).
717 	 */
718 	should_stop_tx_queue = !!(priv->can.echo_skb[priv->echo_idx]);
719 
720 	/* stop network tx queue if not enough room to save one more msg too */
721 	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
722 		should_stop_tx_queue |= (room_left <
723 					(sizeof(*msg) + CANFD_MAX_DLEN));
724 	else
725 		should_stop_tx_queue |= (room_left <
726 					(sizeof(*msg) + CAN_MAX_DLEN));
727 
728 	if (should_stop_tx_queue)
729 		netif_stop_queue(ndev);
730 
731 	spin_unlock_irqrestore(&priv->echo_lock, flags);
732 
733 	/* write the skb on the interface */
734 	priv->write_tx_msg(priv, msg);
735 
736 	return NETDEV_TX_OK;
737 }
738 
739 static const struct net_device_ops peak_canfd_netdev_ops = {
740 	.ndo_open = peak_canfd_open,
741 	.ndo_stop = peak_canfd_close,
742 	.ndo_start_xmit = peak_canfd_start_xmit,
743 	.ndo_change_mtu = can_change_mtu,
744 };
745 
746 struct net_device *alloc_peak_canfd_dev(int sizeof_priv, int index,
747 					int echo_skb_max)
748 {
749 	struct net_device *ndev;
750 	struct peak_canfd_priv *priv;
751 
752 	/* we DO support local echo */
753 	if (echo_skb_max < 0)
754 		echo_skb_max = PCANFD_ECHO_SKB_MAX;
755 
756 	/* allocate the candev object */
757 	ndev = alloc_candev(sizeof_priv, echo_skb_max);
758 	if (!ndev)
759 		return NULL;
760 
761 	priv = netdev_priv(ndev);
762 
763 	/* complete now socket-can initialization side */
764 	priv->can.state = CAN_STATE_STOPPED;
765 	priv->can.bittiming_const = &peak_canfd_nominal_const;
766 	priv->can.data_bittiming_const = &peak_canfd_data_const;
767 
768 	priv->can.do_set_mode = peak_canfd_set_mode;
769 	priv->can.do_get_berr_counter = peak_canfd_get_berr_counter;
770 	priv->can.do_set_bittiming = peak_canfd_set_bittiming;
771 	priv->can.do_set_data_bittiming = peak_canfd_set_data_bittiming;
772 	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
773 				       CAN_CTRLMODE_LISTENONLY |
774 				       CAN_CTRLMODE_3_SAMPLES |
775 				       CAN_CTRLMODE_FD |
776 				       CAN_CTRLMODE_FD_NON_ISO |
777 				       CAN_CTRLMODE_BERR_REPORTING;
778 
779 	priv->ndev = ndev;
780 	priv->index = index;
781 	priv->cmd_len = 0;
782 	spin_lock_init(&priv->echo_lock);
783 
784 	ndev->flags |= IFF_ECHO;
785 	ndev->netdev_ops = &peak_canfd_netdev_ops;
786 	ndev->dev_id = index;
787 
788 	return ndev;
789 }
790