2 * Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
3 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
4 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the version 2 of the GNU General Public License
8 * as published by the Free Software Foundation
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 #include <linux/module.h>
21 #include <linux/kernel.h>
22 #include <linux/slab.h>
23 #include <linux/netdevice.h>
24 #include <linux/if_arp.h>
25 #include <linux/can.h>
26 #include <linux/can/dev.h>
27 #include <linux/can/netlink.h>
28 #include <net/rtnetlink.h>
30 #define MOD_DESC "CAN device driver interface"
32 MODULE_DESCRIPTION(MOD_DESC);
33 MODULE_LICENSE("GPL v2");
34 MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
36 #ifdef CONFIG_CAN_CALC_BITTIMING
37 #define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
40 * Bit-timing calculation derived from:
42 * Code based on LinCAN sources and H8S2638 project
43 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
44 * Copyright 2005 Stanislav Marek
45 * email: pisa@cmp.felk.cvut.cz
47 * Calculates proper bit-timing parameters for a specified bit-rate
48 * and sample-point, which can then be used to set the bit-timing
49 * registers of the CAN controller. You can find more information
50 * in the header file linux/can/netlink.h.
52 static int can_update_spt(const struct can_bittiming_const *btc,
53 int sampl_pt, int tseg, int *tseg1, int *tseg2)
55 *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
56 if (*tseg2 < btc->tseg2_min)
57 *tseg2 = btc->tseg2_min;
58 if (*tseg2 > btc->tseg2_max)
59 *tseg2 = btc->tseg2_max;
60 *tseg1 = tseg - *tseg2;
61 if (*tseg1 > btc->tseg1_max) {
62 *tseg1 = btc->tseg1_max;
63 *tseg2 = tseg - *tseg1;
65 return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
68 static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
70 struct can_priv *priv = netdev_priv(dev);
71 const struct can_bittiming_const *btc = priv->bittiming_const;
72 long rate, best_rate = 0;
73 long best_error = 1000000000, error = 0;
74 int best_tseg = 0, best_brp = 0, brp = 0;
75 int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0;
76 int spt_error = 1000, spt = 0, sampl_pt;
79 if (!priv->bittiming_const)
82 /* Use CIA recommended sample points */
83 if (bt->sample_point) {
84 sampl_pt = bt->sample_point;
86 if (bt->bitrate > 800000)
88 else if (bt->bitrate > 500000)
94 /* tseg even = round down, odd = round up */
95 for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
96 tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
97 tsegall = 1 + tseg / 2;
98 /* Compute all possible tseg choices (tseg=tseg1+tseg2) */
99 brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
100 /* chose brp step which is possible in system */
101 brp = (brp / btc->brp_inc) * btc->brp_inc;
102 if ((brp < btc->brp_min) || (brp > btc->brp_max))
104 rate = priv->clock.freq / (brp * tsegall);
105 error = bt->bitrate - rate;
106 /* tseg brp biterror */
109 if (error > best_error)
113 spt = can_update_spt(btc, sampl_pt, tseg / 2,
115 error = sampl_pt - spt;
118 if (error > spt_error)
122 best_tseg = tseg / 2;
130 /* Error in one-tenth of a percent */
131 error = (best_error * 1000) / bt->bitrate;
132 if (error > CAN_CALC_MAX_ERROR) {
133 dev_err(dev->dev.parent,
134 "bitrate error %ld.%ld%% too high\n",
135 error / 10, error % 10);
138 dev_warn(dev->dev.parent, "bitrate error %ld.%ld%%\n",
139 error / 10, error % 10);
143 /* real sample point */
144 bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg,
147 v64 = (u64)best_brp * 1000000000UL;
148 do_div(v64, priv->clock.freq);
150 bt->prop_seg = tseg1 / 2;
151 bt->phase_seg1 = tseg1 - bt->prop_seg;
152 bt->phase_seg2 = tseg2;
154 /* check for sjw user settings */
155 if (!bt->sjw || !btc->sjw_max)
158 /* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
159 if (bt->sjw > btc->sjw_max)
160 bt->sjw = btc->sjw_max;
161 /* bt->sjw must not be higher than tseg2 */
168 bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1));
172 #else /* !CONFIG_CAN_CALC_BITTIMING */
173 static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
175 dev_err(dev->dev.parent, "bit-timing calculation not available\n");
178 #endif /* CONFIG_CAN_CALC_BITTIMING */
181 * Checks the validity of the specified bit-timing parameters prop_seg,
182 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
183 * prescaler value brp. You can find more information in the header
184 * file linux/can/netlink.h.
186 static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt)
188 struct can_priv *priv = netdev_priv(dev);
189 const struct can_bittiming_const *btc = priv->bittiming_const;
193 if (!priv->bittiming_const)
196 tseg1 = bt->prop_seg + bt->phase_seg1;
199 if (bt->sjw > btc->sjw_max ||
200 tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
201 bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
204 brp64 = (u64)priv->clock.freq * (u64)bt->tq;
205 if (btc->brp_inc > 1)
206 do_div(brp64, btc->brp_inc);
207 brp64 += 500000000UL - 1;
208 do_div(brp64, 1000000000UL); /* the practicable BRP */
209 if (btc->brp_inc > 1)
210 brp64 *= btc->brp_inc;
211 bt->brp = (u32)brp64;
213 if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
216 alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
217 bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
218 bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;
223 static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt)
225 struct can_priv *priv = netdev_priv(dev);
228 /* Check if the CAN device has bit-timing parameters */
229 if (priv->bittiming_const) {
231 /* Non-expert mode? Check if the bitrate has been pre-defined */
233 /* Determine bit-timing parameters */
234 err = can_calc_bittiming(dev, bt);
236 /* Check bit-timing params and calculate proper brp */
237 err = can_fixup_bittiming(dev, bt);
246 * Local echo of CAN messages
248 * CAN network devices *should* support a local echo functionality
249 * (see Documentation/networking/can.txt). To test the handling of CAN
250 * interfaces that do not support the local echo both driver types are
251 * implemented. In the case that the driver does not support the echo
252 * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
253 * to perform the echo as a fallback solution.
255 static void can_flush_echo_skb(struct net_device *dev)
257 struct can_priv *priv = netdev_priv(dev);
258 struct net_device_stats *stats = &dev->stats;
261 for (i = 0; i < priv->echo_skb_max; i++) {
262 if (priv->echo_skb[i]) {
263 kfree_skb(priv->echo_skb[i]);
264 priv->echo_skb[i] = NULL;
266 stats->tx_aborted_errors++;
272 * Put the skb on the stack to be looped backed locally lateron
274 * The function is typically called in the start_xmit function
275 * of the device driver. The driver must protect access to
276 * priv->echo_skb, if necessary.
278 void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
281 struct can_priv *priv = netdev_priv(dev);
283 BUG_ON(idx >= priv->echo_skb_max);
285 /* check flag whether this packet has to be looped back */
286 if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK) {
291 if (!priv->echo_skb[idx]) {
292 struct sock *srcsk = skb->sk;
294 if (atomic_read(&skb->users) != 1) {
295 struct sk_buff *old_skb = skb;
297 skb = skb_clone(old_skb, GFP_ATOMIC);
306 /* make settings for echo to reduce code in irq context */
307 skb->protocol = htons(ETH_P_CAN);
308 skb->pkt_type = PACKET_BROADCAST;
309 skb->ip_summed = CHECKSUM_UNNECESSARY;
312 /* save this skb for tx interrupt echo handling */
313 priv->echo_skb[idx] = skb;
315 /* locking problem with netif_stop_queue() ?? */
316 dev_err(dev->dev.parent, "%s: BUG! echo_skb is occupied!\n",
321 EXPORT_SYMBOL_GPL(can_put_echo_skb);
324 * Get the skb from the stack and loop it back locally
326 * The function is typically called when the TX done interrupt
327 * is handled in the device driver. The driver must protect
328 * access to priv->echo_skb, if necessary.
330 void can_get_echo_skb(struct net_device *dev, unsigned int idx)
332 struct can_priv *priv = netdev_priv(dev);
334 BUG_ON(idx >= priv->echo_skb_max);
336 if (priv->echo_skb[idx]) {
337 netif_rx(priv->echo_skb[idx]);
338 priv->echo_skb[idx] = NULL;
341 EXPORT_SYMBOL_GPL(can_get_echo_skb);
344 * Remove the skb from the stack and free it.
346 * The function is typically called when TX failed.
348 void can_free_echo_skb(struct net_device *dev, unsigned int idx)
350 struct can_priv *priv = netdev_priv(dev);
352 BUG_ON(idx >= priv->echo_skb_max);
354 if (priv->echo_skb[idx]) {
355 dev_kfree_skb_any(priv->echo_skb[idx]);
356 priv->echo_skb[idx] = NULL;
359 EXPORT_SYMBOL_GPL(can_free_echo_skb);
362 * CAN device restart for bus-off recovery
364 void can_restart(unsigned long data)
366 struct net_device *dev = (struct net_device *)data;
367 struct can_priv *priv = netdev_priv(dev);
368 struct net_device_stats *stats = &dev->stats;
370 struct can_frame *cf;
373 BUG_ON(netif_carrier_ok(dev));
376 * No synchronization needed because the device is bus-off and
377 * no messages can come in or go out.
379 can_flush_echo_skb(dev);
381 /* send restart message upstream */
382 skb = alloc_can_err_skb(dev, &cf);
387 cf->can_id |= CAN_ERR_RESTARTED;
392 stats->rx_bytes += cf->can_dlc;
395 dev_dbg(dev->dev.parent, "restarted\n");
396 priv->can_stats.restarts++;
398 /* Now restart the device */
399 err = priv->do_set_mode(dev, CAN_MODE_START);
401 netif_carrier_on(dev);
403 dev_err(dev->dev.parent, "Error %d during restart", err);
406 int can_restart_now(struct net_device *dev)
408 struct can_priv *priv = netdev_priv(dev);
411 * A manual restart is only permitted if automatic restart is
412 * disabled and the device is in the bus-off state
414 if (priv->restart_ms)
416 if (priv->state != CAN_STATE_BUS_OFF)
419 /* Runs as soon as possible in the timer context */
420 mod_timer(&priv->restart_timer, jiffies);
428 * This functions should be called when the device goes bus-off to
429 * tell the netif layer that no more packets can be sent or received.
430 * If enabled, a timer is started to trigger bus-off recovery.
432 void can_bus_off(struct net_device *dev)
434 struct can_priv *priv = netdev_priv(dev);
436 dev_dbg(dev->dev.parent, "bus-off\n");
438 netif_carrier_off(dev);
439 priv->can_stats.bus_off++;
441 if (priv->restart_ms)
442 mod_timer(&priv->restart_timer,
443 jiffies + (priv->restart_ms * HZ) / 1000);
445 EXPORT_SYMBOL_GPL(can_bus_off);
447 static void can_setup(struct net_device *dev)
449 dev->type = ARPHRD_CAN;
450 dev->mtu = sizeof(struct can_frame);
451 dev->hard_header_len = 0;
453 dev->tx_queue_len = 10;
455 /* New-style flags. */
456 dev->flags = IFF_NOARP;
457 dev->features = NETIF_F_NO_CSUM;
460 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
464 skb = netdev_alloc_skb(dev, sizeof(struct can_frame));
468 skb->protocol = htons(ETH_P_CAN);
469 skb->pkt_type = PACKET_BROADCAST;
470 skb->ip_summed = CHECKSUM_UNNECESSARY;
472 skb_reset_mac_header(skb);
473 skb_reset_network_header(skb);
474 skb_reset_transport_header(skb);
476 *cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
477 memset(*cf, 0, sizeof(struct can_frame));
481 EXPORT_SYMBOL_GPL(alloc_can_skb);
483 struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
487 skb = alloc_can_skb(dev, cf);
491 (*cf)->can_id = CAN_ERR_FLAG;
492 (*cf)->can_dlc = CAN_ERR_DLC;
496 EXPORT_SYMBOL_GPL(alloc_can_err_skb);
499 * Allocate and setup space for the CAN network device
501 struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
503 struct net_device *dev;
504 struct can_priv *priv;
508 size = ALIGN(sizeof_priv, sizeof(struct sk_buff *)) +
509 echo_skb_max * sizeof(struct sk_buff *);
513 dev = alloc_netdev(size, "can%d", can_setup);
517 priv = netdev_priv(dev);
520 priv->echo_skb_max = echo_skb_max;
521 priv->echo_skb = (void *)priv +
522 ALIGN(sizeof_priv, sizeof(struct sk_buff *));
525 priv->state = CAN_STATE_STOPPED;
527 init_timer(&priv->restart_timer);
531 EXPORT_SYMBOL_GPL(alloc_candev);
534 * Free space of the CAN network device
536 void free_candev(struct net_device *dev)
540 EXPORT_SYMBOL_GPL(free_candev);
543 * Common open function when the device gets opened.
545 * This function should be called in the open function of the device
548 int open_candev(struct net_device *dev)
550 struct can_priv *priv = netdev_priv(dev);
552 if (!priv->bittiming.tq && !priv->bittiming.bitrate) {
553 dev_err(dev->dev.parent, "bit-timing not yet defined\n");
557 /* Switch carrier on if device was stopped while in bus-off state */
558 if (!netif_carrier_ok(dev))
559 netif_carrier_on(dev);
561 setup_timer(&priv->restart_timer, can_restart, (unsigned long)dev);
565 EXPORT_SYMBOL_GPL(open_candev);
568 * Common close function for cleanup before the device gets closed.
570 * This function should be called in the close function of the device
573 void close_candev(struct net_device *dev)
575 struct can_priv *priv = netdev_priv(dev);
577 del_timer_sync(&priv->restart_timer);
578 can_flush_echo_skb(dev);
580 EXPORT_SYMBOL_GPL(close_candev);
583 * CAN netlink interface
585 static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
586 [IFLA_CAN_STATE] = { .type = NLA_U32 },
587 [IFLA_CAN_CTRLMODE] = { .len = sizeof(struct can_ctrlmode) },
588 [IFLA_CAN_RESTART_MS] = { .type = NLA_U32 },
589 [IFLA_CAN_RESTART] = { .type = NLA_U32 },
590 [IFLA_CAN_BITTIMING] = { .len = sizeof(struct can_bittiming) },
591 [IFLA_CAN_BITTIMING_CONST]
592 = { .len = sizeof(struct can_bittiming_const) },
593 [IFLA_CAN_CLOCK] = { .len = sizeof(struct can_clock) },
594 [IFLA_CAN_BERR_COUNTER] = { .len = sizeof(struct can_berr_counter) },
597 static int can_changelink(struct net_device *dev,
598 struct nlattr *tb[], struct nlattr *data[])
600 struct can_priv *priv = netdev_priv(dev);
603 /* We need synchronization with dev->stop() */
606 if (data[IFLA_CAN_CTRLMODE]) {
607 struct can_ctrlmode *cm;
609 /* Do not allow changing controller mode while running */
610 if (dev->flags & IFF_UP)
612 cm = nla_data(data[IFLA_CAN_CTRLMODE]);
614 /* check whether changed bits are allowed to be modified */
615 if (cm->mask & ~priv->ctrlmode_supported)
618 /* clear bits to be modified and copy the flag values */
619 priv->ctrlmode &= ~cm->mask;
620 priv->ctrlmode |= (cm->flags & cm->mask);
623 if (data[IFLA_CAN_BITTIMING]) {
624 struct can_bittiming bt;
626 /* Do not allow changing bittiming while running */
627 if (dev->flags & IFF_UP)
629 memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt));
630 if ((!bt.bitrate && !bt.tq) || (bt.bitrate && bt.tq))
632 err = can_get_bittiming(dev, &bt);
635 memcpy(&priv->bittiming, &bt, sizeof(bt));
637 if (priv->do_set_bittiming) {
638 /* Finally, set the bit-timing registers */
639 err = priv->do_set_bittiming(dev);
645 if (data[IFLA_CAN_RESTART_MS]) {
646 /* Do not allow changing restart delay while running */
647 if (dev->flags & IFF_UP)
649 priv->restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]);
652 if (data[IFLA_CAN_RESTART]) {
653 /* Do not allow a restart while not running */
654 if (!(dev->flags & IFF_UP))
656 err = can_restart_now(dev);
664 static size_t can_get_size(const struct net_device *dev)
666 struct can_priv *priv = netdev_priv(dev);
669 size = nla_total_size(sizeof(u32)); /* IFLA_CAN_STATE */
670 size += nla_total_size(sizeof(struct can_ctrlmode)); /* IFLA_CAN_CTRLMODE */
671 size += nla_total_size(sizeof(u32)); /* IFLA_CAN_RESTART_MS */
672 size += nla_total_size(sizeof(struct can_bittiming)); /* IFLA_CAN_BITTIMING */
673 size += nla_total_size(sizeof(struct can_clock)); /* IFLA_CAN_CLOCK */
674 if (priv->do_get_berr_counter) /* IFLA_CAN_BERR_COUNTER */
675 size += nla_total_size(sizeof(struct can_berr_counter));
676 if (priv->bittiming_const) /* IFLA_CAN_BITTIMING_CONST */
677 size += nla_total_size(sizeof(struct can_bittiming_const));
682 static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
684 struct can_priv *priv = netdev_priv(dev);
685 struct can_ctrlmode cm = {.flags = priv->ctrlmode};
686 struct can_berr_counter bec;
687 enum can_state state = priv->state;
689 if (priv->do_get_state)
690 priv->do_get_state(dev, &state);
691 NLA_PUT_U32(skb, IFLA_CAN_STATE, state);
692 NLA_PUT(skb, IFLA_CAN_CTRLMODE, sizeof(cm), &cm);
693 NLA_PUT_U32(skb, IFLA_CAN_RESTART_MS, priv->restart_ms);
694 NLA_PUT(skb, IFLA_CAN_BITTIMING,
695 sizeof(priv->bittiming), &priv->bittiming);
696 NLA_PUT(skb, IFLA_CAN_CLOCK, sizeof(priv->clock), &priv->clock);
697 if (priv->do_get_berr_counter && !priv->do_get_berr_counter(dev, &bec))
698 NLA_PUT(skb, IFLA_CAN_BERR_COUNTER, sizeof(bec), &bec);
699 if (priv->bittiming_const)
700 NLA_PUT(skb, IFLA_CAN_BITTIMING_CONST,
701 sizeof(*priv->bittiming_const), priv->bittiming_const);
709 static size_t can_get_xstats_size(const struct net_device *dev)
711 return sizeof(struct can_device_stats);
714 static int can_fill_xstats(struct sk_buff *skb, const struct net_device *dev)
716 struct can_priv *priv = netdev_priv(dev);
718 NLA_PUT(skb, IFLA_INFO_XSTATS,
719 sizeof(priv->can_stats), &priv->can_stats);
727 static int can_newlink(struct net *src_net, struct net_device *dev,
728 struct nlattr *tb[], struct nlattr *data[])
733 static void can_dellink(struct net_device *dev, struct list_head *head)
738 static struct rtnl_link_ops can_link_ops __read_mostly = {
740 .maxtype = IFLA_CAN_MAX,
741 .policy = can_policy,
743 .newlink = can_newlink,
744 .changelink = can_changelink,
745 .dellink = can_dellink,
746 .get_size = can_get_size,
747 .fill_info = can_fill_info,
748 .get_xstats_size = can_get_xstats_size,
749 .fill_xstats = can_fill_xstats,
753 * Register the CAN network device
755 int register_candev(struct net_device *dev)
757 dev->rtnl_link_ops = &can_link_ops;
758 return register_netdev(dev);
760 EXPORT_SYMBOL_GPL(register_candev);
763 * Unregister the CAN network device
765 void unregister_candev(struct net_device *dev)
767 unregister_netdev(dev);
769 EXPORT_SYMBOL_GPL(unregister_candev);
771 static __init int can_dev_init(void)
775 err = rtnl_link_register(&can_link_ops);
777 printk(KERN_INFO MOD_DESC "\n");
781 module_init(can_dev_init);
783 static __exit void can_dev_exit(void)
785 rtnl_link_unregister(&can_link_ops);
787 module_exit(can_dev_exit);
789 MODULE_ALIAS_RTNL_LINK("can");