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 		spin_unlock_irqrestore(&priv->echo_lock, flags);
266 
267 		/* count bytes of the echo instead of skb */
268 		stats->tx_bytes += cf_len;
269 		stats->tx_packets++;
270 
271 		/* restart tx queue (a slot is free) */
272 		netif_wake_queue(priv->ndev);
273 
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 		unsigned long flags;
337 
338 		if (priv->enable_tx_path) {
339 			int err = priv->enable_tx_path(priv);
340 
341 			if (err)
342 				return err;
343 		}
344 
345 		/* restart network queue only if echo skb array is free */
346 		spin_lock_irqsave(&priv->echo_lock, flags);
347 
348 		if (!priv->can.echo_skb[priv->echo_idx]) {
349 			spin_unlock_irqrestore(&priv->echo_lock, flags);
350 
351 			netif_wake_queue(ndev);
352 		} else {
353 			spin_unlock_irqrestore(&priv->echo_lock, flags);
354 		}
355 
356 		return 0;
357 	}
358 
359 	skb = alloc_can_err_skb(ndev, &cf);
360 
361 	/* test state error bits according to their priority */
362 	if (pucan_status_is_busoff(msg)) {
363 		netdev_dbg(ndev, "Bus-off entry status\n");
364 		priv->can.state = CAN_STATE_BUS_OFF;
365 		priv->can.can_stats.bus_off++;
366 		can_bus_off(ndev);
367 		if (skb)
368 			cf->can_id |= CAN_ERR_BUSOFF;
369 
370 	} else if (pucan_status_is_passive(msg)) {
371 		netdev_dbg(ndev, "Error passive status\n");
372 		priv->can.state = CAN_STATE_ERROR_PASSIVE;
373 		priv->can.can_stats.error_passive++;
374 		if (skb) {
375 			cf->can_id |= CAN_ERR_CRTL;
376 			cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
377 					CAN_ERR_CRTL_TX_PASSIVE :
378 					CAN_ERR_CRTL_RX_PASSIVE;
379 			cf->data[6] = priv->bec.txerr;
380 			cf->data[7] = priv->bec.rxerr;
381 		}
382 
383 	} else if (pucan_status_is_warning(msg)) {
384 		netdev_dbg(ndev, "Error warning status\n");
385 		priv->can.state = CAN_STATE_ERROR_WARNING;
386 		priv->can.can_stats.error_warning++;
387 		if (skb) {
388 			cf->can_id |= CAN_ERR_CRTL;
389 			cf->data[1] = (priv->bec.txerr > priv->bec.rxerr) ?
390 					CAN_ERR_CRTL_TX_WARNING :
391 					CAN_ERR_CRTL_RX_WARNING;
392 			cf->data[6] = priv->bec.txerr;
393 			cf->data[7] = priv->bec.rxerr;
394 		}
395 
396 	} else if (priv->can.state != CAN_STATE_ERROR_ACTIVE) {
397 		/* back to ERROR_ACTIVE */
398 		netdev_dbg(ndev, "Error active status\n");
399 		can_change_state(ndev, cf, CAN_STATE_ERROR_ACTIVE,
400 				 CAN_STATE_ERROR_ACTIVE);
401 	} else {
402 		dev_kfree_skb(skb);
403 		return 0;
404 	}
405 
406 	if (!skb) {
407 		stats->rx_dropped++;
408 		return -ENOMEM;
409 	}
410 
411 	stats->rx_packets++;
412 	stats->rx_bytes += cf->can_dlc;
413 	netif_rx(skb);
414 
415 	return 0;
416 }
417 
418 /* handle uCAN Rx overflow notification */
419 static int pucan_handle_cache_critical(struct peak_canfd_priv *priv)
420 {
421 	struct net_device_stats *stats = &priv->ndev->stats;
422 	struct can_frame *cf;
423 	struct sk_buff *skb;
424 
425 	stats->rx_over_errors++;
426 	stats->rx_errors++;
427 
428 	skb = alloc_can_err_skb(priv->ndev, &cf);
429 	if (!skb) {
430 		stats->rx_dropped++;
431 		return -ENOMEM;
432 	}
433 
434 	cf->can_id |= CAN_ERR_CRTL;
435 	cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
436 
437 	cf->data[6] = priv->bec.txerr;
438 	cf->data[7] = priv->bec.rxerr;
439 
440 	stats->rx_bytes += cf->can_dlc;
441 	stats->rx_packets++;
442 	netif_rx(skb);
443 
444 	return 0;
445 }
446 
447 /* handle a single uCAN message */
448 int peak_canfd_handle_msg(struct peak_canfd_priv *priv,
449 			  struct pucan_rx_msg *msg)
450 {
451 	u16 msg_type = le16_to_cpu(msg->type);
452 	int msg_size = le16_to_cpu(msg->size);
453 	int err;
454 
455 	if (!msg_size || !msg_type) {
456 		/* null packet found: end of list */
457 		goto exit;
458 	}
459 
460 	switch (msg_type) {
461 	case PUCAN_MSG_CAN_RX:
462 		err = pucan_handle_can_rx(priv, (struct pucan_rx_msg *)msg);
463 		break;
464 	case PUCAN_MSG_ERROR:
465 		err = pucan_handle_error(priv, (struct pucan_error_msg *)msg);
466 		break;
467 	case PUCAN_MSG_STATUS:
468 		err = pucan_handle_status(priv, (struct pucan_status_msg *)msg);
469 		break;
470 	case PUCAN_MSG_CACHE_CRITICAL:
471 		err = pucan_handle_cache_critical(priv);
472 		break;
473 	default:
474 		err = 0;
475 	}
476 
477 	if (err < 0)
478 		return err;
479 
480 exit:
481 	return msg_size;
482 }
483 
484 /* handle a list of rx_count messages from rx_msg memory address */
485 int peak_canfd_handle_msgs_list(struct peak_canfd_priv *priv,
486 				struct pucan_rx_msg *msg_list, int msg_count)
487 {
488 	void *msg_ptr = msg_list;
489 	int i, msg_size = 0;
490 
491 	for (i = 0; i < msg_count; i++) {
492 		msg_size = peak_canfd_handle_msg(priv, msg_ptr);
493 
494 		/* a null packet can be found at the end of a list */
495 		if (msg_size <= 0)
496 			break;
497 
498 		msg_ptr += msg_size;
499 	}
500 
501 	if (msg_size < 0)
502 		return msg_size;
503 
504 	return i;
505 }
506 
507 static int peak_canfd_start(struct peak_canfd_priv *priv)
508 {
509 	int err;
510 
511 	err = pucan_clr_err_counters(priv);
512 	if (err)
513 		goto err_exit;
514 
515 	priv->echo_idx = 0;
516 
517 	priv->bec.txerr = 0;
518 	priv->bec.rxerr = 0;
519 
520 	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
521 		err = pucan_set_listen_only_mode(priv);
522 	else
523 		err = pucan_set_normal_mode(priv);
524 
525 err_exit:
526 	return err;
527 }
528 
529 static void peak_canfd_stop(struct peak_canfd_priv *priv)
530 {
531 	int err;
532 
533 	/* go back to RESET mode */
534 	err = pucan_set_reset_mode(priv);
535 	if (err) {
536 		netdev_err(priv->ndev, "channel %u reset failed\n",
537 			   priv->index);
538 	} else {
539 		/* abort last Tx (MUST be done in RESET mode only!) */
540 		pucan_tx_abort(priv, PUCAN_TX_ABORT_FLUSH);
541 	}
542 }
543 
544 static int peak_canfd_set_mode(struct net_device *ndev, enum can_mode mode)
545 {
546 	struct peak_canfd_priv *priv = netdev_priv(ndev);
547 
548 	switch (mode) {
549 	case CAN_MODE_START:
550 		peak_canfd_start(priv);
551 		netif_wake_queue(ndev);
552 		break;
553 	default:
554 		return -EOPNOTSUPP;
555 	}
556 
557 	return 0;
558 }
559 
560 static int peak_canfd_get_berr_counter(const struct net_device *ndev,
561 				       struct can_berr_counter *bec)
562 {
563 	struct peak_canfd_priv *priv = netdev_priv(ndev);
564 
565 	*bec = priv->bec;
566 	return 0;
567 }
568 
569 static int peak_canfd_open(struct net_device *ndev)
570 {
571 	struct peak_canfd_priv *priv = netdev_priv(ndev);
572 	int i, err = 0;
573 
574 	err = open_candev(ndev);
575 	if (err) {
576 		netdev_err(ndev, "open_candev() failed, error %d\n", err);
577 		goto err_exit;
578 	}
579 
580 	err = pucan_set_reset_mode(priv);
581 	if (err)
582 		goto err_close;
583 
584 	if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
585 		if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
586 			err = pucan_clr_options(priv, PUCAN_OPTION_CANDFDISO);
587 		else
588 			err = pucan_set_options(priv, PUCAN_OPTION_CANDFDISO);
589 
590 		if (err)
591 			goto err_close;
592 	}
593 
594 	/* set option: get rx/tx error counters */
595 	err = pucan_set_options(priv, PUCAN_OPTION_ERROR);
596 	if (err)
597 		goto err_close;
598 
599 	/* accept all standard CAN ID */
600 	for (i = 0; i <= PUCAN_FLTSTD_ROW_IDX_MAX; i++)
601 		pucan_set_std_filter(priv, i, 0xffffffff);
602 
603 	err = peak_canfd_start(priv);
604 	if (err)
605 		goto err_close;
606 
607 	/* receiving the RB status says when Tx path is ready */
608 	err = pucan_setup_rx_barrier(priv);
609 	if (!err)
610 		goto err_exit;
611 
612 err_close:
613 	close_candev(ndev);
614 err_exit:
615 	return err;
616 }
617 
618 static int peak_canfd_set_bittiming(struct net_device *ndev)
619 {
620 	struct peak_canfd_priv *priv = netdev_priv(ndev);
621 
622 	return pucan_set_timing_slow(priv, &priv->can.bittiming);
623 }
624 
625 static int peak_canfd_set_data_bittiming(struct net_device *ndev)
626 {
627 	struct peak_canfd_priv *priv = netdev_priv(ndev);
628 
629 	return pucan_set_timing_fast(priv, &priv->can.data_bittiming);
630 }
631 
632 static int peak_canfd_close(struct net_device *ndev)
633 {
634 	struct peak_canfd_priv *priv = netdev_priv(ndev);
635 
636 	netif_stop_queue(ndev);
637 	peak_canfd_stop(priv);
638 	close_candev(ndev);
639 
640 	return 0;
641 }
642 
643 static netdev_tx_t peak_canfd_start_xmit(struct sk_buff *skb,
644 					 struct net_device *ndev)
645 {
646 	struct peak_canfd_priv *priv = netdev_priv(ndev);
647 	struct net_device_stats *stats = &ndev->stats;
648 	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
649 	struct pucan_tx_msg *msg;
650 	u16 msg_size, msg_flags;
651 	unsigned long flags;
652 	bool should_stop_tx_queue;
653 	int room_left;
654 	u8 can_dlc;
655 
656 	if (can_dropped_invalid_skb(ndev, skb))
657 		return NETDEV_TX_OK;
658 
659 	msg_size = ALIGN(sizeof(*msg) + cf->len, 4);
660 	msg = priv->alloc_tx_msg(priv, msg_size, &room_left);
661 
662 	/* should never happen except under bus-off condition and (auto-)restart
663 	 * mechanism
664 	 */
665 	if (!msg) {
666 		stats->tx_dropped++;
667 		netif_stop_queue(ndev);
668 		return NETDEV_TX_BUSY;
669 	}
670 
671 	msg->size = cpu_to_le16(msg_size);
672 	msg->type = cpu_to_le16(PUCAN_MSG_CAN_TX);
673 	msg_flags = 0;
674 
675 	if (cf->can_id & CAN_EFF_FLAG) {
676 		msg_flags |= PUCAN_MSG_EXT_ID;
677 		msg->can_id = cpu_to_le32(cf->can_id & CAN_EFF_MASK);
678 	} else {
679 		msg->can_id = cpu_to_le32(cf->can_id & CAN_SFF_MASK);
680 	}
681 
682 	if (can_is_canfd_skb(skb)) {
683 		/* CAN FD frame format */
684 		can_dlc = can_len2dlc(cf->len);
685 
686 		msg_flags |= PUCAN_MSG_EXT_DATA_LEN;
687 
688 		if (cf->flags & CANFD_BRS)
689 			msg_flags |= PUCAN_MSG_BITRATE_SWITCH;
690 
691 		if (cf->flags & CANFD_ESI)
692 			msg_flags |= PUCAN_MSG_ERROR_STATE_IND;
693 	} else {
694 		/* CAN 2.0 frame format */
695 		can_dlc = cf->len;
696 
697 		if (cf->can_id & CAN_RTR_FLAG)
698 			msg_flags |= PUCAN_MSG_RTR;
699 	}
700 
701 	/* always ask loopback for echo management */
702 	msg_flags |= PUCAN_MSG_LOOPED_BACK;
703 
704 	/* set driver specific bit to differentiate with application loopback */
705 	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
706 		msg_flags |= PUCAN_MSG_SELF_RECEIVE;
707 
708 	msg->flags = cpu_to_le16(msg_flags);
709 	msg->channel_dlc = PUCAN_MSG_CHANNEL_DLC(priv->index, can_dlc);
710 	memcpy(msg->d, cf->data, cf->len);
711 
712 	/* struct msg client field is used as an index in the echo skbs ring */
713 	msg->client = priv->echo_idx;
714 
715 	spin_lock_irqsave(&priv->echo_lock, flags);
716 
717 	/* prepare and save echo skb in internal slot */
718 	can_put_echo_skb(skb, ndev, priv->echo_idx);
719 
720 	/* move echo index to the next slot */
721 	priv->echo_idx = (priv->echo_idx + 1) % priv->can.echo_skb_max;
722 
723 	/* if next slot is not free, stop network queue (no slot free in echo
724 	 * skb ring means that the controller did not write these frames on
725 	 * the bus: no need to continue).
726 	 */
727 	should_stop_tx_queue = !!(priv->can.echo_skb[priv->echo_idx]);
728 
729 	spin_unlock_irqrestore(&priv->echo_lock, flags);
730 
731 	/* write the skb on the interface */
732 	priv->write_tx_msg(priv, msg);
733 
734 	/* stop network tx queue if not enough room to save one more msg too */
735 	if (priv->can.ctrlmode & CAN_CTRLMODE_FD)
736 		should_stop_tx_queue |= (room_left <
737 					(sizeof(*msg) + CANFD_MAX_DLEN));
738 	else
739 		should_stop_tx_queue |= (room_left <
740 					(sizeof(*msg) + CAN_MAX_DLEN));
741 
742 	if (should_stop_tx_queue)
743 		netif_stop_queue(ndev);
744 
745 	return NETDEV_TX_OK;
746 }
747 
748 static const struct net_device_ops peak_canfd_netdev_ops = {
749 	.ndo_open = peak_canfd_open,
750 	.ndo_stop = peak_canfd_close,
751 	.ndo_start_xmit = peak_canfd_start_xmit,
752 	.ndo_change_mtu = can_change_mtu,
753 };
754 
755 struct net_device *alloc_peak_canfd_dev(int sizeof_priv, int index,
756 					int echo_skb_max)
757 {
758 	struct net_device *ndev;
759 	struct peak_canfd_priv *priv;
760 
761 	/* we DO support local echo */
762 	if (echo_skb_max < 0)
763 		echo_skb_max = PCANFD_ECHO_SKB_MAX;
764 
765 	/* allocate the candev object */
766 	ndev = alloc_candev(sizeof_priv, echo_skb_max);
767 	if (!ndev)
768 		return NULL;
769 
770 	priv = netdev_priv(ndev);
771 
772 	/* complete now socket-can initialization side */
773 	priv->can.state = CAN_STATE_STOPPED;
774 	priv->can.bittiming_const = &peak_canfd_nominal_const;
775 	priv->can.data_bittiming_const = &peak_canfd_data_const;
776 
777 	priv->can.do_set_mode = peak_canfd_set_mode;
778 	priv->can.do_get_berr_counter = peak_canfd_get_berr_counter;
779 	priv->can.do_set_bittiming = peak_canfd_set_bittiming;
780 	priv->can.do_set_data_bittiming = peak_canfd_set_data_bittiming;
781 	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
782 				       CAN_CTRLMODE_LISTENONLY |
783 				       CAN_CTRLMODE_3_SAMPLES |
784 				       CAN_CTRLMODE_FD |
785 				       CAN_CTRLMODE_FD_NON_ISO |
786 				       CAN_CTRLMODE_BERR_REPORTING;
787 
788 	priv->ndev = ndev;
789 	priv->index = index;
790 	priv->cmd_len = 0;
791 	spin_lock_init(&priv->echo_lock);
792 
793 	ndev->flags |= IFF_ECHO;
794 	ndev->netdev_ops = &peak_canfd_netdev_ops;
795 	ndev->dev_id = index;
796 
797 	return ndev;
798 }
799