4 * Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
5 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
6 * Copyright (C) 2008 Wolfgang Grandegger <wg@grandegger.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the version 2 of the GNU General Public License
10 * as published by the Free Software Foundation
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 #include <linux/module.h>
23 #include <linux/netdevice.h>
24 #include <linux/if_arp.h>
25 #include <linux/can.h>
26 #include <linux/can/dev.h>
27 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
28 #include <net/rtnetlink.h>
33 #define MOD_DESC "CAN netdevice library"
35 MODULE_DESCRIPTION(MOD_DESC);
36 MODULE_LICENSE("GPL v2");
37 MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
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 static int can_update_spt(const struct can_bittiming_const *btc,
48 int sampl_pt, int tseg, int *tseg1, int *tseg2)
50 *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
51 if (*tseg2 < btc->tseg2_min)
52 *tseg2 = btc->tseg2_min;
53 if (*tseg2 > btc->tseg2_max)
54 *tseg2 = btc->tseg2_max;
55 *tseg1 = tseg - *tseg2;
56 if (*tseg1 > btc->tseg1_max) {
57 *tseg1 = btc->tseg1_max;
58 *tseg2 = tseg - *tseg1;
60 return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
63 static int can_calc_bittiming(struct net_device *dev)
65 struct can_priv *priv = netdev_priv(dev);
66 struct can_bittiming *bt = &priv->bittiming;
67 const struct can_bittiming_const *btc = priv->bittiming_const;
68 long rate, best_rate = 0;
69 long best_error = 1000000000, error = 0;
70 int best_tseg = 0, best_brp = 0, brp = 0;
71 int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0;
72 int spt_error = 1000, spt = 0, sampl_pt;
75 if (!priv->bittiming_const)
78 /* Use CIA recommended sample points */
79 if (bt->sample_point) {
80 sampl_pt = bt->sample_point;
82 if (bt->bitrate > 800000)
84 else if (bt->bitrate > 500000)
90 /* tseg even = round down, odd = round up */
91 for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
92 tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
93 tsegall = 1 + tseg / 2;
94 /* Compute all possible tseg choices (tseg=tseg1+tseg2) */
95 brp = bt->clock / (tsegall * bt->bitrate) + tseg % 2;
96 /* chose brp step which is possible in system */
97 brp = (brp / btc->brp_inc) * btc->brp_inc;
98 if ((brp < btc->brp_min) || (brp > btc->brp_max))
100 rate = bt->clock / (brp * tsegall);
101 error = bt->bitrate - rate;
102 /* tseg brp biterror */
105 if (error > best_error)
109 spt = can_update_spt(btc, sampl_pt, tseg / 2,
111 error = sampl_pt - spt;
114 if (error > spt_error)
118 best_tseg = tseg / 2;
125 spt = can_update_spt(btc, sampl_pt, best_tseg, &tseg1, &tseg2);
127 v64 = (u64)best_brp * 1000000000UL;
128 do_div(v64, bt->clock);
130 bt->prop_seg = tseg1 / 2;
131 bt->phase_seg1 = tseg1 - bt->prop_seg;
132 bt->phase_seg2 = tseg2;
137 error = best_error * 1000;
138 error /= bt->bitrate;
139 dev_warn(ND2D(dev), "bitrate error %ld.%ld%%\n",
140 error / 10, error % 10);
146 int can_sample_point(struct can_bittiming *bt)
148 return ((bt->prop_seg + bt->phase_seg1 + 1) * 1000) /
149 (bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1);
152 int can_fixup_bittiming(struct net_device *dev)
154 struct can_priv *priv = netdev_priv(dev);
155 struct can_bittiming *bt = &priv->bittiming;
156 const struct can_bittiming_const *btc = priv->bittiming_const;
161 if (!priv->bittiming_const)
164 tseg1 = bt->prop_seg + bt->phase_seg1;
165 if (bt->sjw > btc->sjw_max ||
166 tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
167 bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
170 brp64 = (u64)bt->clock * (u64)bt->tq;
171 if (btc->brp_inc > 1)
172 do_div(brp64, btc->brp_inc);
173 brp64 += 500000000UL - 1;
174 do_div(brp64, 1000000000UL); /* the practicable BRP */
175 if (btc->brp_inc > 1)
176 brp64 *= btc->brp_inc;
177 bt->brp = (u32)brp64;
179 if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
182 alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
183 bitrate = bt->clock / (bt->brp * alltseg);
184 bt->bitrate = bitrate;
189 int can_set_bittiming(struct net_device *dev)
191 struct can_priv *priv = netdev_priv(dev);
194 /* Check if bit-timing parameters have been pre-defined */
195 if (!priv->bittiming.tq && !priv->bittiming.bitrate)
198 /* Check if the CAN device has bit-timing parameters */
199 if (priv->bittiming_const) {
201 /* Check if bit-timing parameters have already been set */
202 if (priv->bittiming.tq && priv->bittiming.bitrate)
205 /* Non-expert mode? Check if the bitrate has been pre-defined */
206 if (!priv->bittiming.tq)
207 /* Determine bit-timing parameters */
208 err = can_calc_bittiming(dev);
210 /* Check bit-timing params and calculate proper brp */
211 err = can_fixup_bittiming(dev);
216 if (priv->do_set_bittiming) {
217 /* Finally, set the bit-timing registers */
218 err = priv->do_set_bittiming(dev);
225 EXPORT_SYMBOL(can_set_bittiming);
227 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
228 static struct net_device_stats *can_get_stats(struct net_device *dev)
230 struct can_priv *priv = netdev_priv(dev);
232 return &priv->net_stats;
236 static void can_setup(struct net_device *dev)
238 dev->type = ARPHRD_CAN;
239 dev->mtu = sizeof(struct can_frame);
240 dev->hard_header_len = 0;
242 dev->tx_queue_len = 10;
244 /* New-style flags. */
245 dev->flags = IFF_NOARP;
246 dev->features = NETIF_F_NO_CSUM;
247 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
248 dev->get_stats = can_get_stats;
253 * Function alloc_candev
254 * Allocates and sets up an CAN device
256 struct net_device *alloc_candev(int sizeof_priv)
258 struct net_device *dev;
259 struct can_priv *priv;
261 dev = alloc_netdev(sizeof_priv, "can%d", can_setup);
265 priv = netdev_priv(dev);
267 priv->state = CAN_STATE_STOPPED;
268 spin_lock_init(&priv->irq_lock);
270 init_timer(&priv->timer);
271 priv->timer.expires = 0;
275 EXPORT_SYMBOL(alloc_candev);
277 void free_candev(struct net_device *dev)
281 EXPORT_SYMBOL(free_candev);
284 * Local echo of CAN messages
286 * CAN network devices *should* support a local echo functionality
287 * (see Documentation/networking/can.txt). To test the handling of CAN
288 * interfaces that do not support the local echo both driver types are
289 * implemented. In the case that the driver does not support the echo
290 * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
291 * to perform the echo as a fallback solution.
294 void can_flush_echo_skb(struct net_device *dev)
296 struct can_priv *priv = netdev_priv(dev);
298 struct net_device_stats *stats = dev->get_stats(dev);
302 for (i = 0; i < CAN_ECHO_SKB_MAX; i++) {
303 if (priv->echo_skb[i]) {
304 kfree_skb(priv->echo_skb[i]);
305 priv->echo_skb[i] = NULL;
308 stats->tx_aborted_errors++;
314 void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, int idx)
316 struct can_priv *priv = netdev_priv(dev);
318 /* set flag whether this packet has to be looped back */
319 if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK) {
324 if (!priv->echo_skb[idx]) {
325 struct sock *srcsk = skb->sk;
327 if (atomic_read(&skb->users) != 1) {
328 struct sk_buff *old_skb = skb;
330 skb = skb_clone(old_skb, GFP_ATOMIC);
339 /* make settings for echo to reduce code in irq context */
340 skb->protocol = htons(ETH_P_CAN);
341 skb->pkt_type = PACKET_BROADCAST;
342 skb->ip_summed = CHECKSUM_UNNECESSARY;
345 /* save this skb for tx interrupt echo handling */
346 priv->echo_skb[idx] = skb;
348 /* locking problem with netif_stop_queue() ?? */
349 printk(KERN_ERR "%s: %s: BUG! echo_skb is occupied!\n",
350 dev->name, __func__);
354 EXPORT_SYMBOL(can_put_echo_skb);
356 void can_get_echo_skb(struct net_device *dev, int idx)
358 struct can_priv *priv = netdev_priv(dev);
360 if ((dev->flags & IFF_ECHO) && priv->echo_skb[idx]) {
361 netif_rx(priv->echo_skb[idx]);
362 priv->echo_skb[idx] = NULL;
365 EXPORT_SYMBOL(can_get_echo_skb);
368 * CAN bus-off handling
369 * FIXME: we need some synchronization
371 int can_restart_now(struct net_device *dev)
373 struct can_priv *priv = netdev_priv(dev);
374 struct net_device_stats *stats = dev->get_stats(dev);
376 struct can_frame *cf;
379 if (netif_carrier_ok(dev))
380 netif_carrier_off(dev);
382 /* Cancel restart in progress */
383 if (priv->timer.expires) {
384 del_timer(&priv->timer);
385 priv->timer.expires = 0; /* mark inactive timer */
388 can_flush_echo_skb(dev);
390 err = priv->do_set_mode(dev, CAN_MODE_START);
394 netif_carrier_on(dev);
396 priv->can_stats.restarts++;
398 /* send restart message upstream */
399 skb = dev_alloc_skb(sizeof(struct can_frame));
403 skb->protocol = htons(ETH_P_CAN);
404 cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
405 memset(cf, 0, sizeof(struct can_frame));
406 cf->can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED;
407 cf->can_dlc = CAN_ERR_DLC;
411 dev->last_rx = jiffies;
413 stats->rx_bytes += cf->can_dlc;
418 static void can_restart_after(unsigned long data)
420 struct net_device *dev = (struct net_device *)data;
421 struct can_priv *priv = netdev_priv(dev);
423 priv->timer.expires = 0; /* mark inactive timer */
424 can_restart_now(dev);
427 void can_bus_off(struct net_device *dev)
429 struct can_priv *priv = netdev_priv(dev);
431 netif_carrier_off(dev);
433 if (priv->restart_ms > 0 && !priv->timer.expires) {
435 priv->timer.function = can_restart_after;
436 priv->timer.data = (unsigned long)dev;
437 priv->timer.expires =
438 jiffies + (priv->restart_ms * HZ) / 1000;
439 add_timer(&priv->timer);
442 EXPORT_SYMBOL(can_bus_off);
444 void can_close_cleanup(struct net_device *dev)
446 struct can_priv *priv = netdev_priv(dev);
448 if (priv->timer.expires) {
449 del_timer(&priv->timer);
450 priv->timer.expires = 0;
453 can_flush_echo_skb(dev);
455 EXPORT_SYMBOL(can_close_cleanup);
457 static int can_netdev_notifier_call(struct notifier_block *nb,
461 struct net_device *dev = ndev;
463 if (dev->type != ARPHRD_CAN)
466 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
467 /* omit virtual CAN software network devices */
468 if (dev->rtnl_link_ops) {
469 const struct rtnl_link_ops *ops = dev->rtnl_link_ops;
470 if (!strcmp(ops->kind, "vcan"))
474 /* software CAN devices like 'vcan' do not have private data */
480 case NETDEV_REGISTER:
482 can_create_sysfs(dev);
485 case NETDEV_UNREGISTER:
487 can_remove_sysfs(dev);
494 static struct notifier_block can_netdev_notifier = {
495 .notifier_call = can_netdev_notifier_call,
498 static __init int can_dev_init(void)
500 printk(KERN_INFO MOD_DESC "\n");
502 return register_netdevice_notifier(&can_netdev_notifier);
504 module_init(can_dev_init);
506 static __exit void can_dev_exit(void)
508 unregister_netdevice_notifier(&can_netdev_notifier);
510 module_exit(can_dev_exit);