1 // SPDX-License-Identifier: GPL-2.0
2 
3 /* Driver for ETAS GmbH ES58X USB CAN(-FD) Bus Interfaces.
4  *
5  * File es581_4.c: Adds support to ETAS ES581.4.
6  *
7  * Copyright (c) 2019 Robert Bosch Engineering and Business Solutions. All rights reserved.
8  * Copyright (c) 2020 ETAS K.K.. All rights reserved.
9  * Copyright (c) 2020, 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/units.h>
14 #include <asm/unaligned.h>
15 
16 #include "es58x_core.h"
17 #include "es581_4.h"
18 
19 /**
20  * es581_4_sizeof_rx_tx_msg() - Calculate the actual length of the
21  *	structure of a rx or tx message.
22  * @msg: message of variable length, must have a dlc field.
23  *
24  * Even if RTR frames have actually no payload, the ES58X devices
25  * still expect it. Must be a macro in order to accept several types
26  * (struct es581_4_tx_can_msg and struct es581_4_rx_can_msg) as an
27  * input.
28  *
29  * Return: length of the message.
30  */
31 #define es581_4_sizeof_rx_tx_msg(msg)				\
32 	offsetof(typeof(msg), data[can_cc_dlc2len((msg).dlc)])
33 
es581_4_get_msg_len(const union es58x_urb_cmd * urb_cmd)34 static u16 es581_4_get_msg_len(const union es58x_urb_cmd *urb_cmd)
35 {
36 	return get_unaligned_le16(&urb_cmd->es581_4_urb_cmd.msg_len);
37 }
38 
es581_4_echo_msg(struct es58x_device * es58x_dev,const struct es581_4_urb_cmd * es581_4_urb_cmd)39 static int es581_4_echo_msg(struct es58x_device *es58x_dev,
40 			    const struct es581_4_urb_cmd *es581_4_urb_cmd)
41 {
42 	struct net_device *netdev;
43 	const struct es581_4_bulk_echo_msg *bulk_echo_msg;
44 	const struct es581_4_echo_msg *echo_msg;
45 	u64 *tstamps = es58x_dev->timestamps;
46 	u16 msg_len;
47 	u32 first_packet_idx, packet_idx;
48 	unsigned int dropped = 0;
49 	int i, num_element, ret;
50 
51 	bulk_echo_msg = &es581_4_urb_cmd->bulk_echo_msg;
52 	msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len) -
53 	    sizeof(bulk_echo_msg->channel_no);
54 	num_element = es58x_msg_num_element(es58x_dev->dev,
55 					    bulk_echo_msg->echo_msg, msg_len);
56 	if (num_element <= 0)
57 		return num_element;
58 
59 	ret = es58x_get_netdev(es58x_dev, bulk_echo_msg->channel_no,
60 			       ES581_4_CHANNEL_IDX_OFFSET, &netdev);
61 	if (ret)
62 		return ret;
63 
64 	echo_msg = &bulk_echo_msg->echo_msg[0];
65 	first_packet_idx = get_unaligned_le32(&echo_msg->packet_idx);
66 	packet_idx = first_packet_idx;
67 	for (i = 0; i < num_element; i++) {
68 		u32 tmp_idx;
69 
70 		echo_msg = &bulk_echo_msg->echo_msg[i];
71 		tmp_idx = get_unaligned_le32(&echo_msg->packet_idx);
72 		if (tmp_idx == packet_idx - 1) {
73 			if (net_ratelimit())
74 				netdev_warn(netdev,
75 					    "Received echo packet idx %u twice\n",
76 					    packet_idx - 1);
77 			dropped++;
78 			continue;
79 		}
80 		if (tmp_idx != packet_idx) {
81 			netdev_err(netdev, "Echo packet idx jumped from %u to %u\n",
82 				   packet_idx - 1, echo_msg->packet_idx);
83 			return -EBADMSG;
84 		}
85 
86 		tstamps[i] = get_unaligned_le64(&echo_msg->timestamp);
87 		packet_idx++;
88 	}
89 
90 	netdev->stats.tx_dropped += dropped;
91 	return es58x_can_get_echo_skb(netdev, first_packet_idx,
92 				      tstamps, num_element - dropped);
93 }
94 
es581_4_rx_can_msg(struct es58x_device * es58x_dev,const struct es581_4_urb_cmd * es581_4_urb_cmd,u16 msg_len)95 static int es581_4_rx_can_msg(struct es58x_device *es58x_dev,
96 			      const struct es581_4_urb_cmd *es581_4_urb_cmd,
97 			      u16 msg_len)
98 {
99 	const struct device *dev = es58x_dev->dev;
100 	struct net_device *netdev;
101 	int pkts, num_element, channel_no, ret;
102 
103 	num_element = es58x_msg_num_element(dev, es581_4_urb_cmd->rx_can_msg,
104 					    msg_len);
105 	if (num_element <= 0)
106 		return num_element;
107 
108 	channel_no = es581_4_urb_cmd->rx_can_msg[0].channel_no;
109 	ret = es58x_get_netdev(es58x_dev, channel_no,
110 			       ES581_4_CHANNEL_IDX_OFFSET, &netdev);
111 	if (ret)
112 		return ret;
113 
114 	if (!netif_running(netdev)) {
115 		if (net_ratelimit())
116 			netdev_info(netdev,
117 				    "%s: %s is down, dropping %d rx packets\n",
118 				    __func__, netdev->name, num_element);
119 		netdev->stats.rx_dropped += num_element;
120 		return 0;
121 	}
122 
123 	for (pkts = 0; pkts < num_element; pkts++) {
124 		const struct es581_4_rx_can_msg *rx_can_msg =
125 		    &es581_4_urb_cmd->rx_can_msg[pkts];
126 		u64 tstamp = get_unaligned_le64(&rx_can_msg->timestamp);
127 		canid_t can_id = get_unaligned_le32(&rx_can_msg->can_id);
128 
129 		if (channel_no != rx_can_msg->channel_no)
130 			return -EBADMSG;
131 
132 		ret = es58x_rx_can_msg(netdev, tstamp, rx_can_msg->data,
133 				       can_id, rx_can_msg->flags,
134 				       rx_can_msg->dlc);
135 		if (ret)
136 			break;
137 	}
138 
139 	return ret;
140 }
141 
es581_4_rx_err_msg(struct es58x_device * es58x_dev,const struct es581_4_rx_err_msg * rx_err_msg)142 static int es581_4_rx_err_msg(struct es58x_device *es58x_dev,
143 			      const struct es581_4_rx_err_msg *rx_err_msg)
144 {
145 	struct net_device *netdev;
146 	enum es58x_err error = get_unaligned_le32(&rx_err_msg->error);
147 	int ret;
148 
149 	ret = es58x_get_netdev(es58x_dev, rx_err_msg->channel_no,
150 			       ES581_4_CHANNEL_IDX_OFFSET, &netdev);
151 	if (ret)
152 		return ret;
153 
154 	return es58x_rx_err_msg(netdev, error, 0,
155 				get_unaligned_le64(&rx_err_msg->timestamp));
156 }
157 
es581_4_rx_event_msg(struct es58x_device * es58x_dev,const struct es581_4_rx_event_msg * rx_event_msg)158 static int es581_4_rx_event_msg(struct es58x_device *es58x_dev,
159 				const struct es581_4_rx_event_msg *rx_event_msg)
160 {
161 	struct net_device *netdev;
162 	enum es58x_event event = get_unaligned_le32(&rx_event_msg->event);
163 	int ret;
164 
165 	ret = es58x_get_netdev(es58x_dev, rx_event_msg->channel_no,
166 			       ES581_4_CHANNEL_IDX_OFFSET, &netdev);
167 	if (ret)
168 		return ret;
169 
170 	return es58x_rx_err_msg(netdev, 0, event,
171 				get_unaligned_le64(&rx_event_msg->timestamp));
172 }
173 
es581_4_rx_cmd_ret_u32(struct es58x_device * es58x_dev,const struct es581_4_urb_cmd * es581_4_urb_cmd,enum es58x_ret_type ret_type)174 static int es581_4_rx_cmd_ret_u32(struct es58x_device *es58x_dev,
175 				  const struct es581_4_urb_cmd *es581_4_urb_cmd,
176 				  enum es58x_ret_type ret_type)
177 {
178 	struct net_device *netdev;
179 	const struct es581_4_rx_cmd_ret *rx_cmd_ret;
180 	u16 msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len);
181 	int ret;
182 
183 	ret = es58x_check_msg_len(es58x_dev->dev,
184 				  es581_4_urb_cmd->rx_cmd_ret, msg_len);
185 	if (ret)
186 		return ret;
187 
188 	rx_cmd_ret = &es581_4_urb_cmd->rx_cmd_ret;
189 
190 	ret = es58x_get_netdev(es58x_dev, rx_cmd_ret->channel_no,
191 			       ES581_4_CHANNEL_IDX_OFFSET, &netdev);
192 	if (ret)
193 		return ret;
194 
195 	return es58x_rx_cmd_ret_u32(netdev, ret_type,
196 				    get_unaligned_le32(&rx_cmd_ret->rx_cmd_ret_le32));
197 }
198 
es581_4_tx_ack_msg(struct es58x_device * es58x_dev,const struct es581_4_urb_cmd * es581_4_urb_cmd)199 static int es581_4_tx_ack_msg(struct es58x_device *es58x_dev,
200 			      const struct es581_4_urb_cmd *es581_4_urb_cmd)
201 {
202 	struct net_device *netdev;
203 	const struct es581_4_tx_ack_msg *tx_ack_msg;
204 	u16 msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len);
205 	int ret;
206 
207 	tx_ack_msg = &es581_4_urb_cmd->tx_ack_msg;
208 	ret = es58x_check_msg_len(es58x_dev->dev, *tx_ack_msg, msg_len);
209 	if (ret)
210 		return ret;
211 
212 	if (tx_ack_msg->rx_cmd_ret_u8 != ES58X_RET_U8_OK)
213 		return es58x_rx_cmd_ret_u8(es58x_dev->dev,
214 					   ES58X_RET_TYPE_TX_MSG,
215 					   tx_ack_msg->rx_cmd_ret_u8);
216 
217 	ret = es58x_get_netdev(es58x_dev, tx_ack_msg->channel_no,
218 			       ES581_4_CHANNEL_IDX_OFFSET, &netdev);
219 	if (ret)
220 		return ret;
221 
222 	return es58x_tx_ack_msg(netdev,
223 				get_unaligned_le16(&tx_ack_msg->tx_free_entries),
224 				ES58X_RET_U32_OK);
225 }
226 
es581_4_dispatch_rx_cmd(struct es58x_device * es58x_dev,const struct es581_4_urb_cmd * es581_4_urb_cmd)227 static int es581_4_dispatch_rx_cmd(struct es58x_device *es58x_dev,
228 				   const struct es581_4_urb_cmd *es581_4_urb_cmd)
229 {
230 	const struct device *dev = es58x_dev->dev;
231 	u16 msg_len = get_unaligned_le16(&es581_4_urb_cmd->msg_len);
232 	enum es581_4_rx_type rx_type = es581_4_urb_cmd->rx_can_msg[0].rx_type;
233 	int ret = 0;
234 
235 	switch (rx_type) {
236 	case ES581_4_RX_TYPE_MESSAGE:
237 		return es581_4_rx_can_msg(es58x_dev, es581_4_urb_cmd, msg_len);
238 
239 	case ES581_4_RX_TYPE_ERROR:
240 		ret = es58x_check_msg_len(dev, es581_4_urb_cmd->rx_err_msg,
241 					  msg_len);
242 		if (ret < 0)
243 			return ret;
244 		return es581_4_rx_err_msg(es58x_dev,
245 					  &es581_4_urb_cmd->rx_err_msg);
246 
247 	case ES581_4_RX_TYPE_EVENT:
248 		ret = es58x_check_msg_len(dev, es581_4_urb_cmd->rx_event_msg,
249 					  msg_len);
250 		if (ret < 0)
251 			return ret;
252 		return es581_4_rx_event_msg(es58x_dev,
253 					    &es581_4_urb_cmd->rx_event_msg);
254 
255 	default:
256 		dev_err(dev, "%s: Unknown rx_type 0x%02X\n", __func__, rx_type);
257 		return -EBADRQC;
258 	}
259 }
260 
es581_4_handle_urb_cmd(struct es58x_device * es58x_dev,const union es58x_urb_cmd * urb_cmd)261 static int es581_4_handle_urb_cmd(struct es58x_device *es58x_dev,
262 				  const union es58x_urb_cmd *urb_cmd)
263 {
264 	const struct es581_4_urb_cmd *es581_4_urb_cmd;
265 	struct device *dev = es58x_dev->dev;
266 	u16 msg_len = es581_4_get_msg_len(urb_cmd);
267 	int ret;
268 
269 	es581_4_urb_cmd = &urb_cmd->es581_4_urb_cmd;
270 
271 	if (es581_4_urb_cmd->cmd_type != ES581_4_CAN_COMMAND_TYPE) {
272 		dev_err(dev, "%s: Unknown command type (0x%02X)\n",
273 			__func__, es581_4_urb_cmd->cmd_type);
274 		return -EBADRQC;
275 	}
276 
277 	switch ((enum es581_4_cmd_id)es581_4_urb_cmd->cmd_id) {
278 	case ES581_4_CMD_ID_SET_BITTIMING:
279 		return es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
280 					      ES58X_RET_TYPE_SET_BITTIMING);
281 
282 	case ES581_4_CMD_ID_ENABLE_CHANNEL:
283 		return es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
284 					      ES58X_RET_TYPE_ENABLE_CHANNEL);
285 
286 	case ES581_4_CMD_ID_TX_MSG:
287 		return es581_4_tx_ack_msg(es58x_dev, es581_4_urb_cmd);
288 
289 	case ES581_4_CMD_ID_RX_MSG:
290 		return es581_4_dispatch_rx_cmd(es58x_dev, es581_4_urb_cmd);
291 
292 	case ES581_4_CMD_ID_RESET_RX:
293 		ret = es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
294 					     ES58X_RET_TYPE_RESET_RX);
295 		return ret;
296 
297 	case ES581_4_CMD_ID_RESET_TX:
298 		ret = es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
299 					     ES58X_RET_TYPE_RESET_TX);
300 		return ret;
301 
302 	case ES581_4_CMD_ID_DISABLE_CHANNEL:
303 		return es581_4_rx_cmd_ret_u32(es58x_dev, es581_4_urb_cmd,
304 					      ES58X_RET_TYPE_DISABLE_CHANNEL);
305 
306 	case ES581_4_CMD_ID_TIMESTAMP:
307 		ret = es58x_check_msg_len(dev, es581_4_urb_cmd->timestamp,
308 					  msg_len);
309 		if (ret < 0)
310 			return ret;
311 		es58x_rx_timestamp(es58x_dev,
312 				   get_unaligned_le64(&es581_4_urb_cmd->timestamp));
313 		return 0;
314 
315 	case ES581_4_CMD_ID_ECHO:
316 		return es581_4_echo_msg(es58x_dev, es581_4_urb_cmd);
317 
318 	case ES581_4_CMD_ID_DEVICE_ERR:
319 		ret = es58x_check_msg_len(dev, es581_4_urb_cmd->rx_cmd_ret_u8,
320 					  msg_len);
321 		if (ret)
322 			return ret;
323 		return es58x_rx_cmd_ret_u8(dev, ES58X_RET_TYPE_DEVICE_ERR,
324 					   es581_4_urb_cmd->rx_cmd_ret_u8);
325 
326 	default:
327 		dev_warn(dev, "%s: Unexpected command ID: 0x%02X\n",
328 			 __func__, es581_4_urb_cmd->cmd_id);
329 		return -EBADRQC;
330 	}
331 }
332 
es581_4_fill_urb_header(union es58x_urb_cmd * urb_cmd,u8 cmd_type,u8 cmd_id,u8 channel_idx,u16 msg_len)333 static void es581_4_fill_urb_header(union es58x_urb_cmd *urb_cmd, u8 cmd_type,
334 				    u8 cmd_id, u8 channel_idx, u16 msg_len)
335 {
336 	struct es581_4_urb_cmd *es581_4_urb_cmd = &urb_cmd->es581_4_urb_cmd;
337 
338 	es581_4_urb_cmd->SOF = cpu_to_le16(es581_4_param.tx_start_of_frame);
339 	es581_4_urb_cmd->cmd_type = cmd_type;
340 	es581_4_urb_cmd->cmd_id = cmd_id;
341 	es581_4_urb_cmd->msg_len = cpu_to_le16(msg_len);
342 }
343 
es581_4_tx_can_msg(struct es58x_priv * priv,const struct sk_buff * skb)344 static int es581_4_tx_can_msg(struct es58x_priv *priv,
345 			      const struct sk_buff *skb)
346 {
347 	struct es58x_device *es58x_dev = priv->es58x_dev;
348 	union es58x_urb_cmd *urb_cmd = priv->tx_urb->transfer_buffer;
349 	struct es581_4_urb_cmd *es581_4_urb_cmd = &urb_cmd->es581_4_urb_cmd;
350 	struct can_frame *cf = (struct can_frame *)skb->data;
351 	struct es581_4_tx_can_msg *tx_can_msg;
352 	u16 msg_len;
353 	int ret;
354 
355 	if (can_is_canfd_skb(skb))
356 		return -EMSGSIZE;
357 
358 	if (priv->tx_can_msg_cnt == 0) {
359 		msg_len = sizeof(es581_4_urb_cmd->bulk_tx_can_msg.num_can_msg);
360 		es581_4_fill_urb_header(urb_cmd, ES581_4_CAN_COMMAND_TYPE,
361 					ES581_4_CMD_ID_TX_MSG,
362 					priv->channel_idx, msg_len);
363 		es581_4_urb_cmd->bulk_tx_can_msg.num_can_msg = 0;
364 	} else {
365 		msg_len = es581_4_get_msg_len(urb_cmd);
366 	}
367 
368 	ret = es58x_check_msg_max_len(es58x_dev->dev,
369 				      es581_4_urb_cmd->bulk_tx_can_msg,
370 				      msg_len + sizeof(*tx_can_msg));
371 	if (ret)
372 		return ret;
373 
374 	/* Fill message contents. */
375 	tx_can_msg = (typeof(tx_can_msg))&es581_4_urb_cmd->raw_msg[msg_len];
376 	put_unaligned_le32(es58x_get_raw_can_id(cf), &tx_can_msg->can_id);
377 	put_unaligned_le32(priv->tx_head, &tx_can_msg->packet_idx);
378 	put_unaligned_le16((u16)es58x_get_flags(skb), &tx_can_msg->flags);
379 	tx_can_msg->channel_no = priv->channel_idx + ES581_4_CHANNEL_IDX_OFFSET;
380 	tx_can_msg->dlc = can_get_cc_dlc(cf, priv->can.ctrlmode);
381 
382 	memcpy(tx_can_msg->data, cf->data, cf->len);
383 
384 	/* Calculate new sizes. */
385 	es581_4_urb_cmd->bulk_tx_can_msg.num_can_msg++;
386 	msg_len += es581_4_sizeof_rx_tx_msg(*tx_can_msg);
387 	priv->tx_urb->transfer_buffer_length = es58x_get_urb_cmd_len(es58x_dev,
388 								     msg_len);
389 	es581_4_urb_cmd->msg_len = cpu_to_le16(msg_len);
390 
391 	return 0;
392 }
393 
es581_4_set_bittiming(struct es58x_priv * priv)394 static int es581_4_set_bittiming(struct es58x_priv *priv)
395 {
396 	struct es581_4_tx_conf_msg tx_conf_msg = { 0 };
397 	struct can_bittiming *bt = &priv->can.bittiming;
398 
399 	tx_conf_msg.bitrate = cpu_to_le32(bt->bitrate);
400 	/* bt->sample_point is in tenth of percent. Convert it to percent. */
401 	tx_conf_msg.sample_point = cpu_to_le32(bt->sample_point / 10U);
402 	tx_conf_msg.samples_per_bit = cpu_to_le32(ES58X_SAMPLES_PER_BIT_ONE);
403 	tx_conf_msg.bit_time = cpu_to_le32(can_bit_time(bt));
404 	tx_conf_msg.sjw = cpu_to_le32(bt->sjw);
405 	tx_conf_msg.sync_edge = cpu_to_le32(ES58X_SYNC_EDGE_SINGLE);
406 	tx_conf_msg.physical_layer =
407 	    cpu_to_le32(ES58X_PHYSICAL_LAYER_HIGH_SPEED);
408 	tx_conf_msg.echo_mode = cpu_to_le32(ES58X_ECHO_ON);
409 	tx_conf_msg.channel_no = priv->channel_idx + ES581_4_CHANNEL_IDX_OFFSET;
410 
411 	return es58x_send_msg(priv->es58x_dev, ES581_4_CAN_COMMAND_TYPE,
412 			      ES581_4_CMD_ID_SET_BITTIMING, &tx_conf_msg,
413 			      sizeof(tx_conf_msg), priv->channel_idx);
414 }
415 
es581_4_enable_channel(struct es58x_priv * priv)416 static int es581_4_enable_channel(struct es58x_priv *priv)
417 {
418 	int ret;
419 	u8 msg = priv->channel_idx + ES581_4_CHANNEL_IDX_OFFSET;
420 
421 	ret = es581_4_set_bittiming(priv);
422 	if (ret)
423 		return ret;
424 
425 	return es58x_send_msg(priv->es58x_dev, ES581_4_CAN_COMMAND_TYPE,
426 			      ES581_4_CMD_ID_ENABLE_CHANNEL, &msg, sizeof(msg),
427 			      priv->channel_idx);
428 }
429 
es581_4_disable_channel(struct es58x_priv * priv)430 static int es581_4_disable_channel(struct es58x_priv *priv)
431 {
432 	u8 msg = priv->channel_idx + ES581_4_CHANNEL_IDX_OFFSET;
433 
434 	return es58x_send_msg(priv->es58x_dev, ES581_4_CAN_COMMAND_TYPE,
435 			      ES581_4_CMD_ID_DISABLE_CHANNEL, &msg, sizeof(msg),
436 			      priv->channel_idx);
437 }
438 
es581_4_reset_device(struct es58x_device * es58x_dev)439 static int es581_4_reset_device(struct es58x_device *es58x_dev)
440 {
441 	return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
442 			      ES581_4_CMD_ID_RESET_DEVICE,
443 			      ES58X_EMPTY_MSG, 0, ES58X_CHANNEL_IDX_NA);
444 }
445 
es581_4_get_timestamp(struct es58x_device * es58x_dev)446 static int es581_4_get_timestamp(struct es58x_device *es58x_dev)
447 {
448 	return es58x_send_msg(es58x_dev, ES581_4_CAN_COMMAND_TYPE,
449 			      ES581_4_CMD_ID_TIMESTAMP,
450 			      ES58X_EMPTY_MSG, 0, ES58X_CHANNEL_IDX_NA);
451 }
452 
453 /* Nominal bittiming constants for ES581.4 as specified in the
454  * microcontroller datasheet: "Stellaris(R) LM3S5B91 Microcontroller"
455  * table 17-4 "CAN Protocol Ranges" from Texas Instruments.
456  */
457 static const struct can_bittiming_const es581_4_bittiming_const = {
458 	.name = "ES581.4",
459 	.tseg1_min = 1,
460 	.tseg1_max = 8,
461 	.tseg2_min = 1,
462 	.tseg2_max = 8,
463 	.sjw_max = 4,
464 	.brp_min = 1,
465 	.brp_max = 128,
466 	.brp_inc = 1
467 };
468 
469 const struct es58x_parameters es581_4_param = {
470 	.bittiming_const = &es581_4_bittiming_const,
471 	.data_bittiming_const = NULL,
472 	.tdc_const = NULL,
473 	.bitrate_max = 1 * MEGA /* BPS */,
474 	.clock = {.freq = 50 * MEGA /* Hz */},
475 	.ctrlmode_supported = CAN_CTRLMODE_CC_LEN8_DLC,
476 	.tx_start_of_frame = 0xAFAF,
477 	.rx_start_of_frame = 0xFAFA,
478 	.tx_urb_cmd_max_len = ES581_4_TX_URB_CMD_MAX_LEN,
479 	.rx_urb_cmd_max_len = ES581_4_RX_URB_CMD_MAX_LEN,
480 	/* Size of internal device TX queue is 330.
481 	 *
482 	 * However, we witnessed some ES58X_ERR_PROT_CRC errors from
483 	 * the device and thus, echo_skb_max was lowered to the
484 	 * empirical value of 75 which seems stable and then rounded
485 	 * down to become a power of two.
486 	 *
487 	 * Root cause of those ES58X_ERR_PROT_CRC errors is still
488 	 * unclear.
489 	 */
490 	.fifo_mask = 63, /* echo_skb_max = 64 */
491 	.dql_min_limit = CAN_FRAME_LEN_MAX * 50, /* Empirical value. */
492 	.tx_bulk_max = ES581_4_TX_BULK_MAX,
493 	.urb_cmd_header_len = ES581_4_URB_CMD_HEADER_LEN,
494 	.rx_urb_max = ES58X_RX_URBS_MAX,
495 	.tx_urb_max = ES58X_TX_URBS_MAX
496 };
497 
498 const struct es58x_operators es581_4_ops = {
499 	.get_msg_len = es581_4_get_msg_len,
500 	.handle_urb_cmd = es581_4_handle_urb_cmd,
501 	.fill_urb_header = es581_4_fill_urb_header,
502 	.tx_can_msg = es581_4_tx_can_msg,
503 	.enable_channel = es581_4_enable_channel,
504 	.disable_channel = es581_4_disable_channel,
505 	.reset_device = es581_4_reset_device,
506 	.get_timestamp = es581_4_get_timestamp
507 };
508