1 // SPDX-License-Identifier: GPL-2.0
2 
3 /* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
4  *
5  * File es58x_fd.c: Adds support to ETAS ES582.1 and ES584.1 (naming
6  * convention: we use the term "ES58X FD" when referring to those two
7  * variants together).
8  *
9  * Copyright (c) 2019 Robert Bosch Engineering and Business Solutions. All rights reserved.
10  * Copyright (c) 2020 ETAS K.K.. All rights reserved.
11  * Copyright (c) 2020, 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
12  */
13 
14 #include <linux/kernel.h>
15 #include <asm/unaligned.h>
16 
17 #include "es58x_core.h"
18 #include "es58x_fd.h"
19 
20 /**
21  * es58x_fd_sizeof_rx_tx_msg() - Calculate the actual length of the
22  *	structure of a rx or tx message.
23  * @msg: message of variable length, must have a dlc and a len fields.
24  *
25  * Even if RTR frames have actually no payload, the ES58X devices
26  * still expect it. Must be a macro in order to accept several types
27  * (struct es58x_fd_tx_can_msg and struct es58x_fd_rx_can_msg) as an
28  * input.
29  *
30  * Return: length of the message.
31  */
32 #define es58x_fd_sizeof_rx_tx_msg(msg)					\
33 ({									\
34 	typeof(msg) __msg = (msg);					\
35 	size_t __msg_len;						\
36 									\
37 	if (__msg.flags & ES58X_FLAG_FD_DATA)				\
38 		__msg_len = canfd_sanitize_len(__msg.len);		\
39 	else								\
40 		__msg_len = can_cc_dlc2len(__msg.dlc);			\
41 									\
42 	offsetof(typeof(__msg), data[__msg_len]);			\
43 })
44 
45 static enum es58x_fd_cmd_type es58x_fd_cmd_type(struct net_device *netdev)
46 {
47 	u32 ctrlmode = es58x_priv(netdev)->can.ctrlmode;
48 
49 	if (ctrlmode & (CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO))
50 		return ES58X_FD_CMD_TYPE_CANFD;
51 	else
52 		return ES58X_FD_CMD_TYPE_CAN;
53 }
54 
55 static u16 es58x_fd_get_msg_len(const union es58x_urb_cmd *urb_cmd)
56 {
57 	return get_unaligned_le16(&urb_cmd->es58x_fd_urb_cmd.msg_len);
58 }
59 
60 static int es58x_fd_echo_msg(struct net_device *netdev,
61 			     const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
62 {
63 	struct es58x_priv *priv = es58x_priv(netdev);
64 	const struct es58x_fd_echo_msg *echo_msg;
65 	struct es58x_device *es58x_dev = priv->es58x_dev;
66 	u64 *tstamps = es58x_dev->timestamps;
67 	u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
68 	int i, num_element;
69 	u32 rcv_packet_idx;
70 
71 	const u32 mask = GENMASK(31, sizeof(echo_msg->packet_idx) * 8);
72 
73 	num_element = es58x_msg_num_element(es58x_dev->dev,
74 					    es58x_fd_urb_cmd->echo_msg,
75 					    msg_len);
76 	if (num_element < 0)
77 		return num_element;
78 	echo_msg = es58x_fd_urb_cmd->echo_msg;
79 
80 	rcv_packet_idx = (priv->tx_tail & mask) | echo_msg[0].packet_idx;
81 	for (i = 0; i < num_element; i++) {
82 		if ((u8)rcv_packet_idx != echo_msg[i].packet_idx) {
83 			netdev_err(netdev, "Packet idx jumped from %u to %u\n",
84 				   (u8)rcv_packet_idx - 1,
85 				   echo_msg[i].packet_idx);
86 			return -EBADMSG;
87 		}
88 
89 		tstamps[i] = get_unaligned_le64(&echo_msg[i].timestamp);
90 		rcv_packet_idx++;
91 	}
92 
93 	return es58x_can_get_echo_skb(netdev, priv->tx_tail, tstamps, num_element);
94 }
95 
96 static int es58x_fd_rx_can_msg(struct net_device *netdev,
97 			       const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
98 {
99 	struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
100 	const u8 *rx_can_msg_buf = es58x_fd_urb_cmd->rx_can_msg_buf;
101 	u16 rx_can_msg_buf_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
102 	int pkts, ret;
103 
104 	ret = es58x_check_msg_max_len(es58x_dev->dev,
105 				      es58x_fd_urb_cmd->rx_can_msg_buf,
106 				      rx_can_msg_buf_len);
107 	if (ret)
108 		return ret;
109 
110 	for (pkts = 0; rx_can_msg_buf_len > 0; pkts++) {
111 		const struct es58x_fd_rx_can_msg *rx_can_msg =
112 		    (const struct es58x_fd_rx_can_msg *)rx_can_msg_buf;
113 		bool is_can_fd = !!(rx_can_msg->flags & ES58X_FLAG_FD_DATA);
114 		/* rx_can_msg_len is the length of the rx_can_msg
115 		 * buffer. Not to be confused with rx_can_msg->len
116 		 * which is the length of the CAN payload
117 		 * rx_can_msg->data.
118 		 */
119 		u16 rx_can_msg_len = es58x_fd_sizeof_rx_tx_msg(*rx_can_msg);
120 
121 		if (rx_can_msg_len > rx_can_msg_buf_len) {
122 			netdev_err(netdev,
123 				   "%s: Expected a rx_can_msg of size %d but only %d bytes are left in rx_can_msg_buf\n",
124 				   __func__,
125 				   rx_can_msg_len, rx_can_msg_buf_len);
126 			return -EMSGSIZE;
127 		}
128 		if (rx_can_msg->len > CANFD_MAX_DLEN) {
129 			netdev_err(netdev,
130 				   "%s: Data length is %d but maximum should be %d\n",
131 				   __func__, rx_can_msg->len, CANFD_MAX_DLEN);
132 			return -EMSGSIZE;
133 		}
134 
135 		if (netif_running(netdev)) {
136 			u64 tstamp = get_unaligned_le64(&rx_can_msg->timestamp);
137 			canid_t can_id = get_unaligned_le32(&rx_can_msg->can_id);
138 			u8 dlc;
139 
140 			if (is_can_fd)
141 				dlc = can_fd_len2dlc(rx_can_msg->len);
142 			else
143 				dlc = rx_can_msg->dlc;
144 
145 			ret = es58x_rx_can_msg(netdev, tstamp, rx_can_msg->data,
146 					       can_id, rx_can_msg->flags, dlc);
147 			if (ret)
148 				break;
149 		}
150 
151 		rx_can_msg_buf_len -= rx_can_msg_len;
152 		rx_can_msg_buf += rx_can_msg_len;
153 	}
154 
155 	if (!netif_running(netdev)) {
156 		if (net_ratelimit())
157 			netdev_info(netdev,
158 				    "%s: %s is down, dropping %d rx packets\n",
159 				    __func__, netdev->name, pkts);
160 		netdev->stats.rx_dropped += pkts;
161 	}
162 
163 	return ret;
164 }
165 
166 static int es58x_fd_rx_event_msg(struct net_device *netdev,
167 				 const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
168 {
169 	struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
170 	u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
171 	const struct es58x_fd_rx_event_msg *rx_event_msg;
172 	int ret;
173 
174 	ret = es58x_check_msg_len(es58x_dev->dev, *rx_event_msg, msg_len);
175 	if (ret)
176 		return ret;
177 
178 	rx_event_msg = &es58x_fd_urb_cmd->rx_event_msg;
179 
180 	return es58x_rx_err_msg(netdev, rx_event_msg->error_code,
181 				rx_event_msg->event_code,
182 				get_unaligned_le64(&rx_event_msg->timestamp));
183 }
184 
185 static int es58x_fd_rx_cmd_ret_u32(struct net_device *netdev,
186 				   const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd,
187 				   enum es58x_ret_type cmd_ret_type)
188 {
189 	struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
190 	u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
191 	int ret;
192 
193 	ret = es58x_check_msg_len(es58x_dev->dev,
194 				  es58x_fd_urb_cmd->rx_cmd_ret_le32, msg_len);
195 	if (ret)
196 		return ret;
197 
198 	return es58x_rx_cmd_ret_u32(netdev, cmd_ret_type,
199 				    get_unaligned_le32(&es58x_fd_urb_cmd->rx_cmd_ret_le32));
200 }
201 
202 static int es58x_fd_tx_ack_msg(struct net_device *netdev,
203 			       const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
204 {
205 	struct es58x_device *es58x_dev = es58x_priv(netdev)->es58x_dev;
206 	const struct es58x_fd_tx_ack_msg *tx_ack_msg;
207 	u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
208 	int ret;
209 
210 	tx_ack_msg = &es58x_fd_urb_cmd->tx_ack_msg;
211 	ret = es58x_check_msg_len(es58x_dev->dev, *tx_ack_msg, msg_len);
212 	if (ret)
213 		return ret;
214 
215 	return es58x_tx_ack_msg(netdev,
216 				get_unaligned_le16(&tx_ack_msg->tx_free_entries),
217 				get_unaligned_le32(&tx_ack_msg->rx_cmd_ret_le32));
218 }
219 
220 static int es58x_fd_can_cmd_id(struct es58x_device *es58x_dev,
221 			       const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
222 {
223 	struct net_device *netdev;
224 	int ret;
225 
226 	ret = es58x_get_netdev(es58x_dev, es58x_fd_urb_cmd->channel_idx,
227 			       ES58X_FD_CHANNEL_IDX_OFFSET, &netdev);
228 	if (ret)
229 		return ret;
230 
231 	switch ((enum es58x_fd_can_cmd_id)es58x_fd_urb_cmd->cmd_id) {
232 	case ES58X_FD_CAN_CMD_ID_ENABLE_CHANNEL:
233 		return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
234 					       ES58X_RET_TYPE_ENABLE_CHANNEL);
235 
236 	case ES58X_FD_CAN_CMD_ID_DISABLE_CHANNEL:
237 		return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
238 					       ES58X_RET_TYPE_DISABLE_CHANNEL);
239 
240 	case ES58X_FD_CAN_CMD_ID_TX_MSG:
241 		return es58x_fd_tx_ack_msg(netdev, es58x_fd_urb_cmd);
242 
243 	case ES58X_FD_CAN_CMD_ID_ECHO_MSG:
244 		return es58x_fd_echo_msg(netdev, es58x_fd_urb_cmd);
245 
246 	case ES58X_FD_CAN_CMD_ID_RX_MSG:
247 		return es58x_fd_rx_can_msg(netdev, es58x_fd_urb_cmd);
248 
249 	case ES58X_FD_CAN_CMD_ID_RESET_RX:
250 		return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
251 					       ES58X_RET_TYPE_RESET_RX);
252 
253 	case ES58X_FD_CAN_CMD_ID_RESET_TX:
254 		return es58x_fd_rx_cmd_ret_u32(netdev, es58x_fd_urb_cmd,
255 					       ES58X_RET_TYPE_RESET_TX);
256 
257 	case ES58X_FD_CAN_CMD_ID_ERROR_OR_EVENT_MSG:
258 		return es58x_fd_rx_event_msg(netdev, es58x_fd_urb_cmd);
259 
260 	default:
261 		return -EBADRQC;
262 	}
263 }
264 
265 static int es58x_fd_device_cmd_id(struct es58x_device *es58x_dev,
266 				  const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd)
267 {
268 	u16 msg_len = get_unaligned_le16(&es58x_fd_urb_cmd->msg_len);
269 	int ret;
270 
271 	switch ((enum es58x_fd_dev_cmd_id)es58x_fd_urb_cmd->cmd_id) {
272 	case ES58X_FD_DEV_CMD_ID_TIMESTAMP:
273 		ret = es58x_check_msg_len(es58x_dev->dev,
274 					  es58x_fd_urb_cmd->timestamp, msg_len);
275 		if (ret)
276 			return ret;
277 		es58x_rx_timestamp(es58x_dev,
278 				   get_unaligned_le64(&es58x_fd_urb_cmd->timestamp));
279 		return 0;
280 
281 	default:
282 		return -EBADRQC;
283 	}
284 }
285 
286 static int es58x_fd_handle_urb_cmd(struct es58x_device *es58x_dev,
287 				   const union es58x_urb_cmd *urb_cmd)
288 {
289 	const struct es58x_fd_urb_cmd *es58x_fd_urb_cmd;
290 	int ret;
291 
292 	es58x_fd_urb_cmd = &urb_cmd->es58x_fd_urb_cmd;
293 
294 	switch ((enum es58x_fd_cmd_type)es58x_fd_urb_cmd->cmd_type) {
295 	case ES58X_FD_CMD_TYPE_CAN:
296 	case ES58X_FD_CMD_TYPE_CANFD:
297 		ret = es58x_fd_can_cmd_id(es58x_dev, es58x_fd_urb_cmd);
298 		break;
299 
300 	case ES58X_FD_CMD_TYPE_DEVICE:
301 		ret = es58x_fd_device_cmd_id(es58x_dev, es58x_fd_urb_cmd);
302 		break;
303 
304 	default:
305 		ret = -EBADRQC;
306 		break;
307 	}
308 
309 	if (ret == -EBADRQC)
310 		dev_err(es58x_dev->dev,
311 			"%s: Unknown command type (0x%02X) and command ID (0x%02X) combination\n",
312 			__func__, es58x_fd_urb_cmd->cmd_type,
313 			es58x_fd_urb_cmd->cmd_id);
314 
315 	return ret;
316 }
317 
318 static void es58x_fd_fill_urb_header(union es58x_urb_cmd *urb_cmd, u8 cmd_type,
319 				     u8 cmd_id, u8 channel_idx, u16 msg_len)
320 {
321 	struct es58x_fd_urb_cmd *es58x_fd_urb_cmd = &urb_cmd->es58x_fd_urb_cmd;
322 
323 	es58x_fd_urb_cmd->SOF = cpu_to_le16(es58x_fd_param.tx_start_of_frame);
324 	es58x_fd_urb_cmd->cmd_type = cmd_type;
325 	es58x_fd_urb_cmd->cmd_id = cmd_id;
326 	es58x_fd_urb_cmd->channel_idx = channel_idx;
327 	es58x_fd_urb_cmd->msg_len = cpu_to_le16(msg_len);
328 }
329 
330 static int es58x_fd_tx_can_msg(struct es58x_priv *priv,
331 			       const struct sk_buff *skb)
332 {
333 	struct es58x_device *es58x_dev = priv->es58x_dev;
334 	union es58x_urb_cmd *urb_cmd = priv->tx_urb->transfer_buffer;
335 	struct es58x_fd_urb_cmd *es58x_fd_urb_cmd = &urb_cmd->es58x_fd_urb_cmd;
336 	struct can_frame *cf = (struct can_frame *)skb->data;
337 	struct es58x_fd_tx_can_msg *tx_can_msg;
338 	bool is_fd = can_is_canfd_skb(skb);
339 	u16 msg_len;
340 	int ret;
341 
342 	if (priv->tx_can_msg_cnt == 0) {
343 		msg_len = 0;
344 		es58x_fd_fill_urb_header(urb_cmd,
345 					 is_fd ? ES58X_FD_CMD_TYPE_CANFD
346 					       : ES58X_FD_CMD_TYPE_CAN,
347 					 ES58X_FD_CAN_CMD_ID_TX_MSG_NO_ACK,
348 					 priv->channel_idx, msg_len);
349 	} else {
350 		msg_len = es58x_fd_get_msg_len(urb_cmd);
351 	}
352 
353 	ret = es58x_check_msg_max_len(es58x_dev->dev,
354 				      es58x_fd_urb_cmd->tx_can_msg_buf,
355 				      msg_len + sizeof(*tx_can_msg));
356 	if (ret)
357 		return ret;
358 
359 	/* Fill message contents. */
360 	tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len];
361 	tx_can_msg->packet_idx = (u8)priv->tx_head;
362 	put_unaligned_le32(es58x_get_raw_can_id(cf), &tx_can_msg->can_id);
363 	tx_can_msg->flags = (u8)es58x_get_flags(skb);
364 	if (is_fd)
365 		tx_can_msg->len = cf->len;
366 	else
367 		tx_can_msg->dlc = can_get_cc_dlc(cf, priv->can.ctrlmode);
368 	memcpy(tx_can_msg->data, cf->data, cf->len);
369 
370 	/* Calculate new sizes */
371 	msg_len += es58x_fd_sizeof_rx_tx_msg(*tx_can_msg);
372 	priv->tx_urb->transfer_buffer_length = es58x_get_urb_cmd_len(es58x_dev,
373 								     msg_len);
374 	put_unaligned_le16(msg_len, &es58x_fd_urb_cmd->msg_len);
375 
376 	return 0;
377 }
378 
379 static void es58x_fd_convert_bittiming(struct es58x_fd_bittiming *es58x_fd_bt,
380 				       struct can_bittiming *bt)
381 {
382 	/* The actual value set in the hardware registers is one less
383 	 * than the functional value.
384 	 */
385 	const int offset = 1;
386 
387 	es58x_fd_bt->bitrate = cpu_to_le32(bt->bitrate);
388 	es58x_fd_bt->tseg1 =
389 	    cpu_to_le16(bt->prop_seg + bt->phase_seg1 - offset);
390 	es58x_fd_bt->tseg2 = cpu_to_le16(bt->phase_seg2 - offset);
391 	es58x_fd_bt->brp = cpu_to_le16(bt->brp - offset);
392 	es58x_fd_bt->sjw = cpu_to_le16(bt->sjw - offset);
393 }
394 
395 static int es58x_fd_enable_channel(struct es58x_priv *priv)
396 {
397 	struct es58x_device *es58x_dev = priv->es58x_dev;
398 	struct net_device *netdev = es58x_dev->netdev[priv->channel_idx];
399 	struct es58x_fd_tx_conf_msg tx_conf_msg = { 0 };
400 	u32 ctrlmode;
401 	size_t conf_len = 0;
402 
403 	es58x_fd_convert_bittiming(&tx_conf_msg.nominal_bittiming,
404 				   &priv->can.bittiming);
405 	ctrlmode = priv->can.ctrlmode;
406 
407 	if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
408 		tx_conf_msg.samples_per_bit = ES58X_SAMPLES_PER_BIT_THREE;
409 	else
410 		tx_conf_msg.samples_per_bit = ES58X_SAMPLES_PER_BIT_ONE;
411 	tx_conf_msg.sync_edge = ES58X_SYNC_EDGE_SINGLE;
412 	tx_conf_msg.physical_layer = ES58X_PHYSICAL_LAYER_HIGH_SPEED;
413 	tx_conf_msg.echo_mode = ES58X_ECHO_ON;
414 	if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
415 		tx_conf_msg.ctrlmode |= ES58X_FD_CTRLMODE_PASSIVE;
416 	else
417 		tx_conf_msg.ctrlmode |=  ES58X_FD_CTRLMODE_ACTIVE;
418 
419 	if (ctrlmode & CAN_CTRLMODE_FD_NON_ISO) {
420 		tx_conf_msg.ctrlmode |= ES58X_FD_CTRLMODE_FD_NON_ISO;
421 		tx_conf_msg.canfd_enabled = 1;
422 	} else if (ctrlmode & CAN_CTRLMODE_FD) {
423 		tx_conf_msg.ctrlmode |= ES58X_FD_CTRLMODE_FD;
424 		tx_conf_msg.canfd_enabled = 1;
425 	}
426 
427 	if (tx_conf_msg.canfd_enabled) {
428 		es58x_fd_convert_bittiming(&tx_conf_msg.data_bittiming,
429 					   &priv->can.data_bittiming);
430 
431 		if (priv->can.tdc.tdco) {
432 			tx_conf_msg.tdc_enabled = 1;
433 			tx_conf_msg.tdco = cpu_to_le16(priv->can.tdc.tdco);
434 			tx_conf_msg.tdcf = cpu_to_le16(priv->can.tdc.tdcf);
435 		}
436 
437 		conf_len = ES58X_FD_CANFD_CONF_LEN;
438 	} else {
439 		conf_len = ES58X_FD_CAN_CONF_LEN;
440 	}
441 
442 	return es58x_send_msg(es58x_dev, es58x_fd_cmd_type(netdev),
443 			      ES58X_FD_CAN_CMD_ID_ENABLE_CHANNEL,
444 			      &tx_conf_msg, conf_len, priv->channel_idx);
445 }
446 
447 static int es58x_fd_disable_channel(struct es58x_priv *priv)
448 {
449 	/* The type (ES58X_FD_CMD_TYPE_CAN or ES58X_FD_CMD_TYPE_CANFD) does
450 	 * not matter here.
451 	 */
452 	return es58x_send_msg(priv->es58x_dev, ES58X_FD_CMD_TYPE_CAN,
453 			      ES58X_FD_CAN_CMD_ID_DISABLE_CHANNEL,
454 			      ES58X_EMPTY_MSG, 0, priv->channel_idx);
455 }
456 
457 static int es58x_fd_get_timestamp(struct es58x_device *es58x_dev)
458 {
459 	return es58x_send_msg(es58x_dev, ES58X_FD_CMD_TYPE_DEVICE,
460 			      ES58X_FD_DEV_CMD_ID_TIMESTAMP, ES58X_EMPTY_MSG,
461 			      0, ES58X_CHANNEL_IDX_NA);
462 }
463 
464 /* Nominal bittiming constants for ES582.1 and ES584.1 as specified in
465  * the microcontroller datasheet: "SAM E70/S70/V70/V71 Family" section
466  * 49.6.8 "MCAN Nominal Bit Timing and Prescaler Register" from
467  * Microchip.
468  *
469  * The values from the specification are the hardware register
470  * values. To convert them to the functional values, all ranges were
471  * incremented by 1 (e.g. range [0..n-1] changed to [1..n]).
472  */
473 static const struct can_bittiming_const es58x_fd_nom_bittiming_const = {
474 	.name = "ES582.1/ES584.1",
475 	.tseg1_min = 2,
476 	.tseg1_max = 256,
477 	.tseg2_min = 2,
478 	.tseg2_max = 128,
479 	.sjw_max = 128,
480 	.brp_min = 1,
481 	.brp_max = 512,
482 	.brp_inc = 1
483 };
484 
485 /* Data bittiming constants for ES582.1 and ES584.1 as specified in
486  * the microcontroller datasheet: "SAM E70/S70/V70/V71 Family" section
487  * 49.6.4 "MCAN Data Bit Timing and Prescaler Register" from
488  * Microchip.
489  */
490 static const struct can_bittiming_const es58x_fd_data_bittiming_const = {
491 	.name = "ES582.1/ES584.1",
492 	.tseg1_min = 2,
493 	.tseg1_max = 32,
494 	.tseg2_min = 1,
495 	.tseg2_max = 16,
496 	.sjw_max = 8,
497 	.brp_min = 1,
498 	.brp_max = 32,
499 	.brp_inc = 1
500 };
501 
502 /* Transmission Delay Compensation constants for ES582.1 and ES584.1
503  * as specified in the microcontroller datasheet: "SAM E70/S70/V70/V71
504  * Family" section 49.6.15 "MCAN Transmitter Delay Compensation
505  * Register" from Microchip.
506  */
507 static const struct can_tdc_const es58x_tdc_const = {
508 	.tdcv_max = 0, /* Manual mode not supported. */
509 	.tdco_max = 127,
510 	.tdcf_max = 127
511 };
512 
513 const struct es58x_parameters es58x_fd_param = {
514 	.bittiming_const = &es58x_fd_nom_bittiming_const,
515 	.data_bittiming_const = &es58x_fd_data_bittiming_const,
516 	.tdc_const = &es58x_tdc_const,
517 	/* The devices use NXP TJA1044G transievers which guarantee
518 	 * the timing for data rates up to 5 Mbps. Bitrates up to 8
519 	 * Mbps work in an optimal environment but are not recommended
520 	 * for production environment.
521 	 */
522 	.bitrate_max = 8 * CAN_MBPS,
523 	.clock = {.freq = 80 * CAN_MHZ},
524 	.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_LISTENONLY |
525 	    CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_FD | CAN_CTRLMODE_FD_NON_ISO |
526 	    CAN_CTRLMODE_CC_LEN8_DLC,
527 	.tx_start_of_frame = 0xCEFA,	/* FACE in little endian */
528 	.rx_start_of_frame = 0xFECA,	/* CAFE in little endian */
529 	.tx_urb_cmd_max_len = ES58X_FD_TX_URB_CMD_MAX_LEN,
530 	.rx_urb_cmd_max_len = ES58X_FD_RX_URB_CMD_MAX_LEN,
531 	/* Size of internal device TX queue is 500.
532 	 *
533 	 * However, when reaching value around 278, the device's busy
534 	 * LED turns on and thus maximum value of 500 is never reached
535 	 * in practice. Also, when this value is too high, some error
536 	 * on the echo_msg were witnessed when the device is
537 	 * recovering from bus off.
538 	 *
539 	 * For above reasons, a value that would prevent the device
540 	 * from becoming busy was chosen. In practice, BQL would
541 	 * prevent the value from even getting closer to below
542 	 * maximum, so no impact on performance was measured.
543 	 */
544 	.fifo_mask = 255, /* echo_skb_max = 256 */
545 	.dql_min_limit = CAN_FRAME_LEN_MAX * 15, /* Empirical value. */
546 	.tx_bulk_max = ES58X_FD_TX_BULK_MAX,
547 	.urb_cmd_header_len = ES58X_FD_URB_CMD_HEADER_LEN,
548 	.rx_urb_max = ES58X_RX_URBS_MAX,
549 	.tx_urb_max = ES58X_TX_URBS_MAX
550 };
551 
552 const struct es58x_operators es58x_fd_ops = {
553 	.get_msg_len = es58x_fd_get_msg_len,
554 	.handle_urb_cmd = es58x_fd_handle_urb_cmd,
555 	.fill_urb_header = es58x_fd_fill_urb_header,
556 	.tx_can_msg = es58x_fd_tx_can_msg,
557 	.enable_channel = es58x_fd_enable_channel,
558 	.disable_channel = es58x_fd_disable_channel,
559 	.reset_device = NULL, /* Not implemented in the device firmware. */
560 	.get_timestamp = es58x_fd_get_timestamp
561 };
562