xref: /openbmc/linux/drivers/net/can/mscan/mscan.c (revision 94cdda6b)
1 /*
2  * CAN bus driver for the alone generic (as possible as) MSCAN controller.
3  *
4  * Copyright (C) 2005-2006 Andrey Volkov <avolkov@varma-el.com>,
5  *                         Varma Electronics Oy
6  * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
7  * Copyright (C) 2008-2009 Pengutronix <kernel@pengutronix.de>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the version 2 of the GNU General Public License
11  * as published by the Free Software Foundation
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, see <http://www.gnu.org/licenses/>.
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/interrupt.h>
25 #include <linux/delay.h>
26 #include <linux/netdevice.h>
27 #include <linux/if_arp.h>
28 #include <linux/if_ether.h>
29 #include <linux/list.h>
30 #include <linux/can/dev.h>
31 #include <linux/can/error.h>
32 #include <linux/io.h>
33 
34 #include "mscan.h"
35 
36 static const struct can_bittiming_const mscan_bittiming_const = {
37 	.name = "mscan",
38 	.tseg1_min = 4,
39 	.tseg1_max = 16,
40 	.tseg2_min = 2,
41 	.tseg2_max = 8,
42 	.sjw_max = 4,
43 	.brp_min = 1,
44 	.brp_max = 64,
45 	.brp_inc = 1,
46 };
47 
48 struct mscan_state {
49 	u8 mode;
50 	u8 canrier;
51 	u8 cantier;
52 };
53 
54 static enum can_state state_map[] = {
55 	CAN_STATE_ERROR_ACTIVE,
56 	CAN_STATE_ERROR_WARNING,
57 	CAN_STATE_ERROR_PASSIVE,
58 	CAN_STATE_BUS_OFF
59 };
60 
61 static int mscan_set_mode(struct net_device *dev, u8 mode)
62 {
63 	struct mscan_priv *priv = netdev_priv(dev);
64 	struct mscan_regs __iomem *regs = priv->reg_base;
65 	int ret = 0;
66 	int i;
67 	u8 canctl1;
68 
69 	if (mode != MSCAN_NORMAL_MODE) {
70 		if (priv->tx_active) {
71 			/* Abort transfers before going to sleep */#
72 			out_8(&regs->cantarq, priv->tx_active);
73 			/* Suppress TX done interrupts */
74 			out_8(&regs->cantier, 0);
75 		}
76 
77 		canctl1 = in_8(&regs->canctl1);
78 		if ((mode & MSCAN_SLPRQ) && !(canctl1 & MSCAN_SLPAK)) {
79 			setbits8(&regs->canctl0, MSCAN_SLPRQ);
80 			for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
81 				if (in_8(&regs->canctl1) & MSCAN_SLPAK)
82 					break;
83 				udelay(100);
84 			}
85 			/*
86 			 * The mscan controller will fail to enter sleep mode,
87 			 * while there are irregular activities on bus, like
88 			 * somebody keeps retransmitting. This behavior is
89 			 * undocumented and seems to differ between mscan built
90 			 * in mpc5200b and mpc5200. We proceed in that case,
91 			 * since otherwise the slprq will be kept set and the
92 			 * controller will get stuck. NOTE: INITRQ or CSWAI
93 			 * will abort all active transmit actions, if still
94 			 * any, at once.
95 			 */
96 			if (i >= MSCAN_SET_MODE_RETRIES)
97 				netdev_dbg(dev,
98 					   "device failed to enter sleep mode. "
99 					   "We proceed anyhow.\n");
100 			else
101 				priv->can.state = CAN_STATE_SLEEPING;
102 		}
103 
104 		if ((mode & MSCAN_INITRQ) && !(canctl1 & MSCAN_INITAK)) {
105 			setbits8(&regs->canctl0, MSCAN_INITRQ);
106 			for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
107 				if (in_8(&regs->canctl1) & MSCAN_INITAK)
108 					break;
109 			}
110 			if (i >= MSCAN_SET_MODE_RETRIES)
111 				ret = -ENODEV;
112 		}
113 		if (!ret)
114 			priv->can.state = CAN_STATE_STOPPED;
115 
116 		if (mode & MSCAN_CSWAI)
117 			setbits8(&regs->canctl0, MSCAN_CSWAI);
118 
119 	} else {
120 		canctl1 = in_8(&regs->canctl1);
121 		if (canctl1 & (MSCAN_SLPAK | MSCAN_INITAK)) {
122 			clrbits8(&regs->canctl0, MSCAN_SLPRQ | MSCAN_INITRQ);
123 			for (i = 0; i < MSCAN_SET_MODE_RETRIES; i++) {
124 				canctl1 = in_8(&regs->canctl1);
125 				if (!(canctl1 & (MSCAN_INITAK | MSCAN_SLPAK)))
126 					break;
127 			}
128 			if (i >= MSCAN_SET_MODE_RETRIES)
129 				ret = -ENODEV;
130 			else
131 				priv->can.state = CAN_STATE_ERROR_ACTIVE;
132 		}
133 	}
134 	return ret;
135 }
136 
137 static int mscan_start(struct net_device *dev)
138 {
139 	struct mscan_priv *priv = netdev_priv(dev);
140 	struct mscan_regs __iomem *regs = priv->reg_base;
141 	u8 canrflg;
142 	int err;
143 
144 	out_8(&regs->canrier, 0);
145 
146 	INIT_LIST_HEAD(&priv->tx_head);
147 	priv->prev_buf_id = 0;
148 	priv->cur_pri = 0;
149 	priv->tx_active = 0;
150 	priv->shadow_canrier = 0;
151 	priv->flags = 0;
152 
153 	if (priv->type == MSCAN_TYPE_MPC5121) {
154 		/* Clear pending bus-off condition */
155 		if (in_8(&regs->canmisc) & MSCAN_BOHOLD)
156 			out_8(&regs->canmisc, MSCAN_BOHOLD);
157 	}
158 
159 	err = mscan_set_mode(dev, MSCAN_NORMAL_MODE);
160 	if (err)
161 		return err;
162 
163 	canrflg = in_8(&regs->canrflg);
164 	priv->shadow_statflg = canrflg & MSCAN_STAT_MSK;
165 	priv->can.state = state_map[max(MSCAN_STATE_RX(canrflg),
166 				    MSCAN_STATE_TX(canrflg))];
167 	out_8(&regs->cantier, 0);
168 
169 	/* Enable receive interrupts. */
170 	out_8(&regs->canrier, MSCAN_RX_INTS_ENABLE);
171 
172 	return 0;
173 }
174 
175 static int mscan_restart(struct net_device *dev)
176 {
177 	struct mscan_priv *priv = netdev_priv(dev);
178 
179 	if (priv->type == MSCAN_TYPE_MPC5121) {
180 		struct mscan_regs __iomem *regs = priv->reg_base;
181 
182 		priv->can.state = CAN_STATE_ERROR_ACTIVE;
183 		WARN(!(in_8(&regs->canmisc) & MSCAN_BOHOLD),
184 		     "bus-off state expected\n");
185 		out_8(&regs->canmisc, MSCAN_BOHOLD);
186 		/* Re-enable receive interrupts. */
187 		out_8(&regs->canrier, MSCAN_RX_INTS_ENABLE);
188 	} else {
189 		if (priv->can.state <= CAN_STATE_BUS_OFF)
190 			mscan_set_mode(dev, MSCAN_INIT_MODE);
191 		return mscan_start(dev);
192 	}
193 
194 	return 0;
195 }
196 
197 static netdev_tx_t mscan_start_xmit(struct sk_buff *skb, struct net_device *dev)
198 {
199 	struct can_frame *frame = (struct can_frame *)skb->data;
200 	struct mscan_priv *priv = netdev_priv(dev);
201 	struct mscan_regs __iomem *regs = priv->reg_base;
202 	int i, rtr, buf_id;
203 	u32 can_id;
204 
205 	if (can_dropped_invalid_skb(dev, skb))
206 		return NETDEV_TX_OK;
207 
208 	out_8(&regs->cantier, 0);
209 
210 	i = ~priv->tx_active & MSCAN_TXE;
211 	buf_id = ffs(i) - 1;
212 	switch (hweight8(i)) {
213 	case 0:
214 		netif_stop_queue(dev);
215 		netdev_err(dev, "Tx Ring full when queue awake!\n");
216 		return NETDEV_TX_BUSY;
217 	case 1:
218 		/*
219 		 * if buf_id < 3, then current frame will be send out of order,
220 		 * since buffer with lower id have higher priority (hell..)
221 		 */
222 		netif_stop_queue(dev);
223 	case 2:
224 		if (buf_id < priv->prev_buf_id) {
225 			priv->cur_pri++;
226 			if (priv->cur_pri == 0xff) {
227 				set_bit(F_TX_WAIT_ALL, &priv->flags);
228 				netif_stop_queue(dev);
229 			}
230 		}
231 		set_bit(F_TX_PROGRESS, &priv->flags);
232 		break;
233 	}
234 	priv->prev_buf_id = buf_id;
235 	out_8(&regs->cantbsel, i);
236 
237 	rtr = frame->can_id & CAN_RTR_FLAG;
238 
239 	/* RTR is always the lowest bit of interest, then IDs follow */
240 	if (frame->can_id & CAN_EFF_FLAG) {
241 		can_id = (frame->can_id & CAN_EFF_MASK)
242 			 << (MSCAN_EFF_RTR_SHIFT + 1);
243 		if (rtr)
244 			can_id |= 1 << MSCAN_EFF_RTR_SHIFT;
245 		out_be16(&regs->tx.idr3_2, can_id);
246 
247 		can_id >>= 16;
248 		/* EFF_FLAGS are between the IDs :( */
249 		can_id = (can_id & 0x7) | ((can_id << 2) & 0xffe0)
250 			 | MSCAN_EFF_FLAGS;
251 	} else {
252 		can_id = (frame->can_id & CAN_SFF_MASK)
253 			 << (MSCAN_SFF_RTR_SHIFT + 1);
254 		if (rtr)
255 			can_id |= 1 << MSCAN_SFF_RTR_SHIFT;
256 	}
257 	out_be16(&regs->tx.idr1_0, can_id);
258 
259 	if (!rtr) {
260 		void __iomem *data = &regs->tx.dsr1_0;
261 		u16 *payload = (u16 *)frame->data;
262 
263 		for (i = 0; i < frame->can_dlc / 2; i++) {
264 			out_be16(data, *payload++);
265 			data += 2 + _MSCAN_RESERVED_DSR_SIZE;
266 		}
267 		/* write remaining byte if necessary */
268 		if (frame->can_dlc & 1)
269 			out_8(data, frame->data[frame->can_dlc - 1]);
270 	}
271 
272 	out_8(&regs->tx.dlr, frame->can_dlc);
273 	out_8(&regs->tx.tbpr, priv->cur_pri);
274 
275 	/* Start transmission. */
276 	out_8(&regs->cantflg, 1 << buf_id);
277 
278 	if (!test_bit(F_TX_PROGRESS, &priv->flags))
279 		dev->trans_start = jiffies;
280 
281 	list_add_tail(&priv->tx_queue[buf_id].list, &priv->tx_head);
282 
283 	can_put_echo_skb(skb, dev, buf_id);
284 
285 	/* Enable interrupt. */
286 	priv->tx_active |= 1 << buf_id;
287 	out_8(&regs->cantier, priv->tx_active);
288 
289 	return NETDEV_TX_OK;
290 }
291 
292 static enum can_state get_new_state(struct net_device *dev, u8 canrflg)
293 {
294 	struct mscan_priv *priv = netdev_priv(dev);
295 
296 	if (unlikely(canrflg & MSCAN_CSCIF))
297 		return state_map[max(MSCAN_STATE_RX(canrflg),
298 				 MSCAN_STATE_TX(canrflg))];
299 
300 	return priv->can.state;
301 }
302 
303 static void mscan_get_rx_frame(struct net_device *dev, struct can_frame *frame)
304 {
305 	struct mscan_priv *priv = netdev_priv(dev);
306 	struct mscan_regs __iomem *regs = priv->reg_base;
307 	u32 can_id;
308 	int i;
309 
310 	can_id = in_be16(&regs->rx.idr1_0);
311 	if (can_id & (1 << 3)) {
312 		frame->can_id = CAN_EFF_FLAG;
313 		can_id = ((can_id << 16) | in_be16(&regs->rx.idr3_2));
314 		can_id = ((can_id & 0xffe00000) |
315 			  ((can_id & 0x7ffff) << 2)) >> 2;
316 	} else {
317 		can_id >>= 4;
318 		frame->can_id = 0;
319 	}
320 
321 	frame->can_id |= can_id >> 1;
322 	if (can_id & 1)
323 		frame->can_id |= CAN_RTR_FLAG;
324 
325 	frame->can_dlc = get_can_dlc(in_8(&regs->rx.dlr) & 0xf);
326 
327 	if (!(frame->can_id & CAN_RTR_FLAG)) {
328 		void __iomem *data = &regs->rx.dsr1_0;
329 		u16 *payload = (u16 *)frame->data;
330 
331 		for (i = 0; i < frame->can_dlc / 2; i++) {
332 			*payload++ = in_be16(data);
333 			data += 2 + _MSCAN_RESERVED_DSR_SIZE;
334 		}
335 		/* read remaining byte if necessary */
336 		if (frame->can_dlc & 1)
337 			frame->data[frame->can_dlc - 1] = in_8(data);
338 	}
339 
340 	out_8(&regs->canrflg, MSCAN_RXF);
341 }
342 
343 static void mscan_get_err_frame(struct net_device *dev, struct can_frame *frame,
344 				u8 canrflg)
345 {
346 	struct mscan_priv *priv = netdev_priv(dev);
347 	struct mscan_regs __iomem *regs = priv->reg_base;
348 	struct net_device_stats *stats = &dev->stats;
349 	enum can_state new_state;
350 
351 	netdev_dbg(dev, "error interrupt (canrflg=%#x)\n", canrflg);
352 	frame->can_id = CAN_ERR_FLAG;
353 
354 	if (canrflg & MSCAN_OVRIF) {
355 		frame->can_id |= CAN_ERR_CRTL;
356 		frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
357 		stats->rx_over_errors++;
358 		stats->rx_errors++;
359 	} else {
360 		frame->data[1] = 0;
361 	}
362 
363 	new_state = get_new_state(dev, canrflg);
364 	if (new_state != priv->can.state) {
365 		can_change_state(dev, frame,
366 				 state_map[MSCAN_STATE_TX(canrflg)],
367 				 state_map[MSCAN_STATE_RX(canrflg)]);
368 
369 		if (priv->can.state == CAN_STATE_BUS_OFF) {
370 			/*
371 			 * The MSCAN on the MPC5200 does recover from bus-off
372 			 * automatically. To avoid that we stop the chip doing
373 			 * a light-weight stop (we are in irq-context).
374 			 */
375 			if (priv->type != MSCAN_TYPE_MPC5121) {
376 				out_8(&regs->cantier, 0);
377 				out_8(&regs->canrier, 0);
378 				setbits8(&regs->canctl0,
379 					 MSCAN_SLPRQ | MSCAN_INITRQ);
380 			}
381 			can_bus_off(dev);
382 		}
383 	}
384 	priv->shadow_statflg = canrflg & MSCAN_STAT_MSK;
385 	frame->can_dlc = CAN_ERR_DLC;
386 	out_8(&regs->canrflg, MSCAN_ERR_IF);
387 }
388 
389 static int mscan_rx_poll(struct napi_struct *napi, int quota)
390 {
391 	struct mscan_priv *priv = container_of(napi, struct mscan_priv, napi);
392 	struct net_device *dev = napi->dev;
393 	struct mscan_regs __iomem *regs = priv->reg_base;
394 	struct net_device_stats *stats = &dev->stats;
395 	int npackets = 0;
396 	int ret = 1;
397 	struct sk_buff *skb;
398 	struct can_frame *frame;
399 	u8 canrflg;
400 
401 	while (npackets < quota) {
402 		canrflg = in_8(&regs->canrflg);
403 		if (!(canrflg & (MSCAN_RXF | MSCAN_ERR_IF)))
404 			break;
405 
406 		skb = alloc_can_skb(dev, &frame);
407 		if (!skb) {
408 			if (printk_ratelimit())
409 				netdev_notice(dev, "packet dropped\n");
410 			stats->rx_dropped++;
411 			out_8(&regs->canrflg, canrflg);
412 			continue;
413 		}
414 
415 		if (canrflg & MSCAN_RXF)
416 			mscan_get_rx_frame(dev, frame);
417 		else if (canrflg & MSCAN_ERR_IF)
418 			mscan_get_err_frame(dev, frame, canrflg);
419 
420 		stats->rx_packets++;
421 		stats->rx_bytes += frame->can_dlc;
422 		npackets++;
423 		netif_receive_skb(skb);
424 	}
425 
426 	if (!(in_8(&regs->canrflg) & (MSCAN_RXF | MSCAN_ERR_IF))) {
427 		napi_complete(&priv->napi);
428 		clear_bit(F_RX_PROGRESS, &priv->flags);
429 		if (priv->can.state < CAN_STATE_BUS_OFF)
430 			out_8(&regs->canrier, priv->shadow_canrier);
431 		ret = 0;
432 	}
433 	return ret;
434 }
435 
436 static irqreturn_t mscan_isr(int irq, void *dev_id)
437 {
438 	struct net_device *dev = (struct net_device *)dev_id;
439 	struct mscan_priv *priv = netdev_priv(dev);
440 	struct mscan_regs __iomem *regs = priv->reg_base;
441 	struct net_device_stats *stats = &dev->stats;
442 	u8 cantier, cantflg, canrflg;
443 	irqreturn_t ret = IRQ_NONE;
444 
445 	cantier = in_8(&regs->cantier) & MSCAN_TXE;
446 	cantflg = in_8(&regs->cantflg) & cantier;
447 
448 	if (cantier && cantflg) {
449 		struct list_head *tmp, *pos;
450 
451 		list_for_each_safe(pos, tmp, &priv->tx_head) {
452 			struct tx_queue_entry *entry =
453 			    list_entry(pos, struct tx_queue_entry, list);
454 			u8 mask = entry->mask;
455 
456 			if (!(cantflg & mask))
457 				continue;
458 
459 			out_8(&regs->cantbsel, mask);
460 			stats->tx_bytes += in_8(&regs->tx.dlr);
461 			stats->tx_packets++;
462 			can_get_echo_skb(dev, entry->id);
463 			priv->tx_active &= ~mask;
464 			list_del(pos);
465 		}
466 
467 		if (list_empty(&priv->tx_head)) {
468 			clear_bit(F_TX_WAIT_ALL, &priv->flags);
469 			clear_bit(F_TX_PROGRESS, &priv->flags);
470 			priv->cur_pri = 0;
471 		} else {
472 			dev->trans_start = jiffies;
473 		}
474 
475 		if (!test_bit(F_TX_WAIT_ALL, &priv->flags))
476 			netif_wake_queue(dev);
477 
478 		out_8(&regs->cantier, priv->tx_active);
479 		ret = IRQ_HANDLED;
480 	}
481 
482 	canrflg = in_8(&regs->canrflg);
483 	if ((canrflg & ~MSCAN_STAT_MSK) &&
484 	    !test_and_set_bit(F_RX_PROGRESS, &priv->flags)) {
485 		if (canrflg & ~MSCAN_STAT_MSK) {
486 			priv->shadow_canrier = in_8(&regs->canrier);
487 			out_8(&regs->canrier, 0);
488 			napi_schedule(&priv->napi);
489 			ret = IRQ_HANDLED;
490 		} else {
491 			clear_bit(F_RX_PROGRESS, &priv->flags);
492 		}
493 	}
494 	return ret;
495 }
496 
497 static int mscan_do_set_mode(struct net_device *dev, enum can_mode mode)
498 {
499 	int ret = 0;
500 
501 	switch (mode) {
502 	case CAN_MODE_START:
503 		ret = mscan_restart(dev);
504 		if (ret)
505 			break;
506 		if (netif_queue_stopped(dev))
507 			netif_wake_queue(dev);
508 		break;
509 
510 	default:
511 		ret = -EOPNOTSUPP;
512 		break;
513 	}
514 	return ret;
515 }
516 
517 static int mscan_do_set_bittiming(struct net_device *dev)
518 {
519 	struct mscan_priv *priv = netdev_priv(dev);
520 	struct mscan_regs __iomem *regs = priv->reg_base;
521 	struct can_bittiming *bt = &priv->can.bittiming;
522 	u8 btr0, btr1;
523 
524 	btr0 = BTR0_SET_BRP(bt->brp) | BTR0_SET_SJW(bt->sjw);
525 	btr1 = (BTR1_SET_TSEG1(bt->prop_seg + bt->phase_seg1) |
526 		BTR1_SET_TSEG2(bt->phase_seg2) |
527 		BTR1_SET_SAM(priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES));
528 
529 	netdev_info(dev, "setting BTR0=0x%02x BTR1=0x%02x\n", btr0, btr1);
530 
531 	out_8(&regs->canbtr0, btr0);
532 	out_8(&regs->canbtr1, btr1);
533 
534 	return 0;
535 }
536 
537 static int mscan_get_berr_counter(const struct net_device *dev,
538 				  struct can_berr_counter *bec)
539 {
540 	struct mscan_priv *priv = netdev_priv(dev);
541 	struct mscan_regs __iomem *regs = priv->reg_base;
542 
543 	bec->txerr = in_8(&regs->cantxerr);
544 	bec->rxerr = in_8(&regs->canrxerr);
545 
546 	return 0;
547 }
548 
549 static int mscan_open(struct net_device *dev)
550 {
551 	int ret;
552 	struct mscan_priv *priv = netdev_priv(dev);
553 	struct mscan_regs __iomem *regs = priv->reg_base;
554 
555 	if (priv->clk_ipg) {
556 		ret = clk_prepare_enable(priv->clk_ipg);
557 		if (ret)
558 			goto exit_retcode;
559 	}
560 	if (priv->clk_can) {
561 		ret = clk_prepare_enable(priv->clk_can);
562 		if (ret)
563 			goto exit_dis_ipg_clock;
564 	}
565 
566 	/* common open */
567 	ret = open_candev(dev);
568 	if (ret)
569 		goto exit_dis_can_clock;
570 
571 	napi_enable(&priv->napi);
572 
573 	ret = request_irq(dev->irq, mscan_isr, 0, dev->name, dev);
574 	if (ret < 0) {
575 		netdev_err(dev, "failed to attach interrupt\n");
576 		goto exit_napi_disable;
577 	}
578 
579 	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
580 		setbits8(&regs->canctl1, MSCAN_LISTEN);
581 	else
582 		clrbits8(&regs->canctl1, MSCAN_LISTEN);
583 
584 	ret = mscan_start(dev);
585 	if (ret)
586 		goto exit_free_irq;
587 
588 	netif_start_queue(dev);
589 
590 	return 0;
591 
592 exit_free_irq:
593 	free_irq(dev->irq, dev);
594 exit_napi_disable:
595 	napi_disable(&priv->napi);
596 	close_candev(dev);
597 exit_dis_can_clock:
598 	if (priv->clk_can)
599 		clk_disable_unprepare(priv->clk_can);
600 exit_dis_ipg_clock:
601 	if (priv->clk_ipg)
602 		clk_disable_unprepare(priv->clk_ipg);
603 exit_retcode:
604 	return ret;
605 }
606 
607 static int mscan_close(struct net_device *dev)
608 {
609 	struct mscan_priv *priv = netdev_priv(dev);
610 	struct mscan_regs __iomem *regs = priv->reg_base;
611 
612 	netif_stop_queue(dev);
613 	napi_disable(&priv->napi);
614 
615 	out_8(&regs->cantier, 0);
616 	out_8(&regs->canrier, 0);
617 	mscan_set_mode(dev, MSCAN_INIT_MODE);
618 	close_candev(dev);
619 	free_irq(dev->irq, dev);
620 
621 	if (priv->clk_can)
622 		clk_disable_unprepare(priv->clk_can);
623 	if (priv->clk_ipg)
624 		clk_disable_unprepare(priv->clk_ipg);
625 
626 	return 0;
627 }
628 
629 static const struct net_device_ops mscan_netdev_ops = {
630 	.ndo_open	= mscan_open,
631 	.ndo_stop	= mscan_close,
632 	.ndo_start_xmit	= mscan_start_xmit,
633 	.ndo_change_mtu	= can_change_mtu,
634 };
635 
636 int register_mscandev(struct net_device *dev, int mscan_clksrc)
637 {
638 	struct mscan_priv *priv = netdev_priv(dev);
639 	struct mscan_regs __iomem *regs = priv->reg_base;
640 	u8 ctl1;
641 
642 	ctl1 = in_8(&regs->canctl1);
643 	if (mscan_clksrc)
644 		ctl1 |= MSCAN_CLKSRC;
645 	else
646 		ctl1 &= ~MSCAN_CLKSRC;
647 
648 	if (priv->type == MSCAN_TYPE_MPC5121) {
649 		priv->can.do_get_berr_counter = mscan_get_berr_counter;
650 		ctl1 |= MSCAN_BORM; /* bus-off recovery upon request */
651 	}
652 
653 	ctl1 |= MSCAN_CANE;
654 	out_8(&regs->canctl1, ctl1);
655 	udelay(100);
656 
657 	/* acceptance mask/acceptance code (accept everything) */
658 	out_be16(&regs->canidar1_0, 0);
659 	out_be16(&regs->canidar3_2, 0);
660 	out_be16(&regs->canidar5_4, 0);
661 	out_be16(&regs->canidar7_6, 0);
662 
663 	out_be16(&regs->canidmr1_0, 0xffff);
664 	out_be16(&regs->canidmr3_2, 0xffff);
665 	out_be16(&regs->canidmr5_4, 0xffff);
666 	out_be16(&regs->canidmr7_6, 0xffff);
667 	/* Two 32 bit Acceptance Filters */
668 	out_8(&regs->canidac, MSCAN_AF_32BIT);
669 
670 	mscan_set_mode(dev, MSCAN_INIT_MODE);
671 
672 	return register_candev(dev);
673 }
674 
675 void unregister_mscandev(struct net_device *dev)
676 {
677 	struct mscan_priv *priv = netdev_priv(dev);
678 	struct mscan_regs __iomem *regs = priv->reg_base;
679 	mscan_set_mode(dev, MSCAN_INIT_MODE);
680 	clrbits8(&regs->canctl1, MSCAN_CANE);
681 	unregister_candev(dev);
682 }
683 
684 struct net_device *alloc_mscandev(void)
685 {
686 	struct net_device *dev;
687 	struct mscan_priv *priv;
688 	int i;
689 
690 	dev = alloc_candev(sizeof(struct mscan_priv), MSCAN_ECHO_SKB_MAX);
691 	if (!dev)
692 		return NULL;
693 	priv = netdev_priv(dev);
694 
695 	dev->netdev_ops = &mscan_netdev_ops;
696 
697 	dev->flags |= IFF_ECHO;	/* we support local echo */
698 
699 	netif_napi_add(dev, &priv->napi, mscan_rx_poll, 8);
700 
701 	priv->can.bittiming_const = &mscan_bittiming_const;
702 	priv->can.do_set_bittiming = mscan_do_set_bittiming;
703 	priv->can.do_set_mode = mscan_do_set_mode;
704 	priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
705 		CAN_CTRLMODE_LISTENONLY;
706 
707 	for (i = 0; i < TX_QUEUE_SIZE; i++) {
708 		priv->tx_queue[i].id = i;
709 		priv->tx_queue[i].mask = 1 << i;
710 	}
711 
712 	return dev;
713 }
714 
715 MODULE_AUTHOR("Andrey Volkov <avolkov@varma-el.com>");
716 MODULE_LICENSE("GPL v2");
717 MODULE_DESCRIPTION("CAN port driver for a MSCAN based chips");
718