dev.c revision 451f14439847db302e5104c44458b2dbb4b1829d
1/* 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> 5 * 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 9 * 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. 14 * 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 18 */ 19 20#include <linux/module.h> 21#include <linux/kernel.h> 22#include <linux/netdevice.h> 23#include <linux/if_arp.h> 24#include <linux/can.h> 25#include <linux/can/dev.h> 26#include <linux/can/netlink.h> 27#include <net/rtnetlink.h> 28 29#define MOD_DESC "CAN device driver interface" 30 31MODULE_DESCRIPTION(MOD_DESC); 32MODULE_LICENSE("GPL v2"); 33MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>"); 34 35#ifdef CONFIG_CAN_CALC_BITTIMING 36#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */ 37 38/* 39 * Bit-timing calculation derived from: 40 * 41 * Code based on LinCAN sources and H8S2638 project 42 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz 43 * Copyright 2005 Stanislav Marek 44 * email: pisa@cmp.felk.cvut.cz 45 * 46 * Calculates proper bit-timing parameters for a specified bit-rate 47 * and sample-point, which can then be used to set the bit-timing 48 * registers of the CAN controller. You can find more information 49 * in the header file linux/can/netlink.h. 50 */ 51static int can_update_spt(const struct can_bittiming_const *btc, 52 int sampl_pt, int tseg, int *tseg1, int *tseg2) 53{ 54 *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000; 55 if (*tseg2 < btc->tseg2_min) 56 *tseg2 = btc->tseg2_min; 57 if (*tseg2 > btc->tseg2_max) 58 *tseg2 = btc->tseg2_max; 59 *tseg1 = tseg - *tseg2; 60 if (*tseg1 > btc->tseg1_max) { 61 *tseg1 = btc->tseg1_max; 62 *tseg2 = tseg - *tseg1; 63 } 64 return 1000 * (tseg + 1 - *tseg2) / (tseg + 1); 65} 66 67static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt) 68{ 69 struct can_priv *priv = netdev_priv(dev); 70 const struct can_bittiming_const *btc = priv->bittiming_const; 71 long rate, best_rate = 0; 72 long best_error = 1000000000, error = 0; 73 int best_tseg = 0, best_brp = 0, brp = 0; 74 int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0; 75 int spt_error = 1000, spt = 0, sampl_pt; 76 u64 v64; 77 78 if (!priv->bittiming_const) 79 return -ENOTSUPP; 80 81 /* Use CIA recommended sample points */ 82 if (bt->sample_point) { 83 sampl_pt = bt->sample_point; 84 } else { 85 if (bt->bitrate > 800000) 86 sampl_pt = 750; 87 else if (bt->bitrate > 500000) 88 sampl_pt = 800; 89 else 90 sampl_pt = 875; 91 } 92 93 /* tseg even = round down, odd = round up */ 94 for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1; 95 tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) { 96 tsegall = 1 + tseg / 2; 97 /* Compute all possible tseg choices (tseg=tseg1+tseg2) */ 98 brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2; 99 /* chose brp step which is possible in system */ 100 brp = (brp / btc->brp_inc) * btc->brp_inc; 101 if ((brp < btc->brp_min) || (brp > btc->brp_max)) 102 continue; 103 rate = priv->clock.freq / (brp * tsegall); 104 error = bt->bitrate - rate; 105 /* tseg brp biterror */ 106 if (error < 0) 107 error = -error; 108 if (error > best_error) 109 continue; 110 best_error = error; 111 if (error == 0) { 112 spt = can_update_spt(btc, sampl_pt, tseg / 2, 113 &tseg1, &tseg2); 114 error = sampl_pt - spt; 115 if (error < 0) 116 error = -error; 117 if (error > spt_error) 118 continue; 119 spt_error = error; 120 } 121 best_tseg = tseg / 2; 122 best_brp = brp; 123 best_rate = rate; 124 if (error == 0) 125 break; 126 } 127 128 if (best_error) { 129 /* Error in one-tenth of a percent */ 130 error = (best_error * 1000) / bt->bitrate; 131 if (error > CAN_CALC_MAX_ERROR) { 132 dev_err(dev->dev.parent, 133 "bitrate error %ld.%ld%% too high\n", 134 error / 10, error % 10); 135 return -EDOM; 136 } else { 137 dev_warn(dev->dev.parent, "bitrate error %ld.%ld%%\n", 138 error / 10, error % 10); 139 } 140 } 141 142 /* real sample point */ 143 bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg, 144 &tseg1, &tseg2); 145 146 v64 = (u64)best_brp * 1000000000UL; 147 do_div(v64, priv->clock.freq); 148 bt->tq = (u32)v64; 149 bt->prop_seg = tseg1 / 2; 150 bt->phase_seg1 = tseg1 - bt->prop_seg; 151 bt->phase_seg2 = tseg2; 152 bt->sjw = 1; 153 bt->brp = best_brp; 154 /* real bit-rate */ 155 bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1)); 156 157 return 0; 158} 159#else /* !CONFIG_CAN_CALC_BITTIMING */ 160static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt) 161{ 162 dev_err(dev->dev.parent, "bit-timing calculation not available\n"); 163 return -EINVAL; 164} 165#endif /* CONFIG_CAN_CALC_BITTIMING */ 166 167/* 168 * Checks the validity of the specified bit-timing parameters prop_seg, 169 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate 170 * prescaler value brp. You can find more information in the header 171 * file linux/can/netlink.h. 172 */ 173static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt) 174{ 175 struct can_priv *priv = netdev_priv(dev); 176 const struct can_bittiming_const *btc = priv->bittiming_const; 177 int tseg1, alltseg; 178 u64 brp64; 179 180 if (!priv->bittiming_const) 181 return -ENOTSUPP; 182 183 tseg1 = bt->prop_seg + bt->phase_seg1; 184 if (!bt->sjw) 185 bt->sjw = 1; 186 if (bt->sjw > btc->sjw_max || 187 tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max || 188 bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max) 189 return -ERANGE; 190 191 brp64 = (u64)priv->clock.freq * (u64)bt->tq; 192 if (btc->brp_inc > 1) 193 do_div(brp64, btc->brp_inc); 194 brp64 += 500000000UL - 1; 195 do_div(brp64, 1000000000UL); /* the practicable BRP */ 196 if (btc->brp_inc > 1) 197 brp64 *= btc->brp_inc; 198 bt->brp = (u32)brp64; 199 200 if (bt->brp < btc->brp_min || bt->brp > btc->brp_max) 201 return -EINVAL; 202 203 alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1; 204 bt->bitrate = priv->clock.freq / (bt->brp * alltseg); 205 bt->sample_point = ((tseg1 + 1) * 1000) / alltseg; 206 207 return 0; 208} 209 210int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt) 211{ 212 struct can_priv *priv = netdev_priv(dev); 213 int err; 214 215 /* Check if the CAN device has bit-timing parameters */ 216 if (priv->bittiming_const) { 217 218 /* Non-expert mode? Check if the bitrate has been pre-defined */ 219 if (!bt->tq) 220 /* Determine bit-timing parameters */ 221 err = can_calc_bittiming(dev, bt); 222 else 223 /* Check bit-timing params and calculate proper brp */ 224 err = can_fixup_bittiming(dev, bt); 225 if (err) 226 return err; 227 } 228 229 return 0; 230} 231 232/* 233 * Local echo of CAN messages 234 * 235 * CAN network devices *should* support a local echo functionality 236 * (see Documentation/networking/can.txt). To test the handling of CAN 237 * interfaces that do not support the local echo both driver types are 238 * implemented. In the case that the driver does not support the echo 239 * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core 240 * to perform the echo as a fallback solution. 241 */ 242static void can_flush_echo_skb(struct net_device *dev) 243{ 244 struct can_priv *priv = netdev_priv(dev); 245 struct net_device_stats *stats = &dev->stats; 246 int i; 247 248 for (i = 0; i < CAN_ECHO_SKB_MAX; i++) { 249 if (priv->echo_skb[i]) { 250 kfree_skb(priv->echo_skb[i]); 251 priv->echo_skb[i] = NULL; 252 stats->tx_dropped++; 253 stats->tx_aborted_errors++; 254 } 255 } 256} 257 258/* 259 * Put the skb on the stack to be looped backed locally lateron 260 * 261 * The function is typically called in the start_xmit function 262 * of the device driver. The driver must protect access to 263 * priv->echo_skb, if necessary. 264 */ 265void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, int idx) 266{ 267 struct can_priv *priv = netdev_priv(dev); 268 269 /* check flag whether this packet has to be looped back */ 270 if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK) { 271 kfree_skb(skb); 272 return; 273 } 274 275 if (!priv->echo_skb[idx]) { 276 struct sock *srcsk = skb->sk; 277 278 if (atomic_read(&skb->users) != 1) { 279 struct sk_buff *old_skb = skb; 280 281 skb = skb_clone(old_skb, GFP_ATOMIC); 282 kfree_skb(old_skb); 283 if (!skb) 284 return; 285 } else 286 skb_orphan(skb); 287 288 skb->sk = srcsk; 289 290 /* make settings for echo to reduce code in irq context */ 291 skb->protocol = htons(ETH_P_CAN); 292 skb->pkt_type = PACKET_BROADCAST; 293 skb->ip_summed = CHECKSUM_UNNECESSARY; 294 skb->dev = dev; 295 296 /* save this skb for tx interrupt echo handling */ 297 priv->echo_skb[idx] = skb; 298 } else { 299 /* locking problem with netif_stop_queue() ?? */ 300 dev_err(dev->dev.parent, "%s: BUG! echo_skb is occupied!\n", 301 __func__); 302 kfree_skb(skb); 303 } 304} 305EXPORT_SYMBOL_GPL(can_put_echo_skb); 306 307/* 308 * Get the skb from the stack and loop it back locally 309 * 310 * The function is typically called when the TX done interrupt 311 * is handled in the device driver. The driver must protect 312 * access to priv->echo_skb, if necessary. 313 */ 314void can_get_echo_skb(struct net_device *dev, int idx) 315{ 316 struct can_priv *priv = netdev_priv(dev); 317 318 if ((dev->flags & IFF_ECHO) && priv->echo_skb[idx]) { 319 netif_rx(priv->echo_skb[idx]); 320 priv->echo_skb[idx] = NULL; 321 } 322} 323EXPORT_SYMBOL_GPL(can_get_echo_skb); 324 325/* 326 * CAN device restart for bus-off recovery 327 */ 328void can_restart(unsigned long data) 329{ 330 struct net_device *dev = (struct net_device *)data; 331 struct can_priv *priv = netdev_priv(dev); 332 struct net_device_stats *stats = &dev->stats; 333 struct sk_buff *skb; 334 struct can_frame *cf; 335 int err; 336 337 BUG_ON(netif_carrier_ok(dev)); 338 339 /* 340 * No synchronization needed because the device is bus-off and 341 * no messages can come in or go out. 342 */ 343 can_flush_echo_skb(dev); 344 345 /* send restart message upstream */ 346 skb = dev_alloc_skb(sizeof(struct can_frame)); 347 if (skb == NULL) { 348 err = -ENOMEM; 349 goto restart; 350 } 351 skb->dev = dev; 352 skb->protocol = htons(ETH_P_CAN); 353 cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame)); 354 memset(cf, 0, sizeof(struct can_frame)); 355 cf->can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED; 356 cf->can_dlc = CAN_ERR_DLC; 357 358 netif_rx(skb); 359 360 stats->rx_packets++; 361 stats->rx_bytes += cf->can_dlc; 362 363restart: 364 dev_dbg(dev->dev.parent, "restarted\n"); 365 priv->can_stats.restarts++; 366 367 /* Now restart the device */ 368 err = priv->do_set_mode(dev, CAN_MODE_START); 369 370 netif_carrier_on(dev); 371 if (err) 372 dev_err(dev->dev.parent, "Error %d during restart", err); 373} 374 375int can_restart_now(struct net_device *dev) 376{ 377 struct can_priv *priv = netdev_priv(dev); 378 379 /* 380 * A manual restart is only permitted if automatic restart is 381 * disabled and the device is in the bus-off state 382 */ 383 if (priv->restart_ms) 384 return -EINVAL; 385 if (priv->state != CAN_STATE_BUS_OFF) 386 return -EBUSY; 387 388 /* Runs as soon as possible in the timer context */ 389 mod_timer(&priv->restart_timer, jiffies); 390 391 return 0; 392} 393 394/* 395 * CAN bus-off 396 * 397 * This functions should be called when the device goes bus-off to 398 * tell the netif layer that no more packets can be sent or received. 399 * If enabled, a timer is started to trigger bus-off recovery. 400 */ 401void can_bus_off(struct net_device *dev) 402{ 403 struct can_priv *priv = netdev_priv(dev); 404 405 dev_dbg(dev->dev.parent, "bus-off\n"); 406 407 netif_carrier_off(dev); 408 priv->can_stats.bus_off++; 409 410 if (priv->restart_ms) 411 mod_timer(&priv->restart_timer, 412 jiffies + (priv->restart_ms * HZ) / 1000); 413} 414EXPORT_SYMBOL_GPL(can_bus_off); 415 416static void can_setup(struct net_device *dev) 417{ 418 dev->type = ARPHRD_CAN; 419 dev->mtu = sizeof(struct can_frame); 420 dev->hard_header_len = 0; 421 dev->addr_len = 0; 422 dev->tx_queue_len = 10; 423 424 /* New-style flags. */ 425 dev->flags = IFF_NOARP; 426 dev->features = NETIF_F_NO_CSUM; 427} 428 429/* 430 * Allocate and setup space for the CAN network device 431 */ 432struct net_device *alloc_candev(int sizeof_priv) 433{ 434 struct net_device *dev; 435 struct can_priv *priv; 436 437 dev = alloc_netdev(sizeof_priv, "can%d", can_setup); 438 if (!dev) 439 return NULL; 440 441 priv = netdev_priv(dev); 442 443 priv->state = CAN_STATE_STOPPED; 444 445 init_timer(&priv->restart_timer); 446 447 return dev; 448} 449EXPORT_SYMBOL_GPL(alloc_candev); 450 451/* 452 * Free space of the CAN network device 453 */ 454void free_candev(struct net_device *dev) 455{ 456 free_netdev(dev); 457} 458EXPORT_SYMBOL_GPL(free_candev); 459 460/* 461 * Common open function when the device gets opened. 462 * 463 * This function should be called in the open function of the device 464 * driver. 465 */ 466int open_candev(struct net_device *dev) 467{ 468 struct can_priv *priv = netdev_priv(dev); 469 470 if (!priv->bittiming.tq && !priv->bittiming.bitrate) { 471 dev_err(dev->dev.parent, "bit-timing not yet defined\n"); 472 return -EINVAL; 473 } 474 475 /* Switch carrier on if device was stopped while in bus-off state */ 476 if (!netif_carrier_ok(dev)) 477 netif_carrier_on(dev); 478 479 setup_timer(&priv->restart_timer, can_restart, (unsigned long)dev); 480 481 return 0; 482} 483EXPORT_SYMBOL_GPL(open_candev); 484 485/* 486 * Common close function for cleanup before the device gets closed. 487 * 488 * This function should be called in the close function of the device 489 * driver. 490 */ 491void close_candev(struct net_device *dev) 492{ 493 struct can_priv *priv = netdev_priv(dev); 494 495 if (del_timer_sync(&priv->restart_timer)) 496 dev_put(dev); 497 can_flush_echo_skb(dev); 498} 499EXPORT_SYMBOL_GPL(close_candev); 500 501/* 502 * CAN netlink interface 503 */ 504static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = { 505 [IFLA_CAN_STATE] = { .type = NLA_U32 }, 506 [IFLA_CAN_CTRLMODE] = { .len = sizeof(struct can_ctrlmode) }, 507 [IFLA_CAN_RESTART_MS] = { .type = NLA_U32 }, 508 [IFLA_CAN_RESTART] = { .type = NLA_U32 }, 509 [IFLA_CAN_BITTIMING] = { .len = sizeof(struct can_bittiming) }, 510 [IFLA_CAN_BITTIMING_CONST] 511 = { .len = sizeof(struct can_bittiming_const) }, 512 [IFLA_CAN_CLOCK] = { .len = sizeof(struct can_clock) }, 513}; 514 515static int can_changelink(struct net_device *dev, 516 struct nlattr *tb[], struct nlattr *data[]) 517{ 518 struct can_priv *priv = netdev_priv(dev); 519 int err; 520 521 /* We need synchronization with dev->stop() */ 522 ASSERT_RTNL(); 523 524 if (data[IFLA_CAN_CTRLMODE]) { 525 struct can_ctrlmode *cm; 526 527 /* Do not allow changing controller mode while running */ 528 if (dev->flags & IFF_UP) 529 return -EBUSY; 530 cm = nla_data(data[IFLA_CAN_CTRLMODE]); 531 priv->ctrlmode &= ~cm->mask; 532 priv->ctrlmode |= cm->flags; 533 } 534 535 if (data[IFLA_CAN_BITTIMING]) { 536 struct can_bittiming bt; 537 538 /* Do not allow changing bittiming while running */ 539 if (dev->flags & IFF_UP) 540 return -EBUSY; 541 memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt)); 542 if ((!bt.bitrate && !bt.tq) || (bt.bitrate && bt.tq)) 543 return -EINVAL; 544 err = can_get_bittiming(dev, &bt); 545 if (err) 546 return err; 547 memcpy(&priv->bittiming, &bt, sizeof(bt)); 548 549 if (priv->do_set_bittiming) { 550 /* Finally, set the bit-timing registers */ 551 err = priv->do_set_bittiming(dev); 552 if (err) 553 return err; 554 } 555 } 556 557 if (data[IFLA_CAN_RESTART_MS]) { 558 /* Do not allow changing restart delay while running */ 559 if (dev->flags & IFF_UP) 560 return -EBUSY; 561 priv->restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]); 562 } 563 564 if (data[IFLA_CAN_RESTART]) { 565 /* Do not allow a restart while not running */ 566 if (!(dev->flags & IFF_UP)) 567 return -EINVAL; 568 err = can_restart_now(dev); 569 if (err) 570 return err; 571 } 572 573 return 0; 574} 575 576static int can_fill_info(struct sk_buff *skb, const struct net_device *dev) 577{ 578 struct can_priv *priv = netdev_priv(dev); 579 struct can_ctrlmode cm = {.flags = priv->ctrlmode}; 580 enum can_state state = priv->state; 581 582 if (priv->do_get_state) 583 priv->do_get_state(dev, &state); 584 NLA_PUT_U32(skb, IFLA_CAN_STATE, state); 585 NLA_PUT(skb, IFLA_CAN_CTRLMODE, sizeof(cm), &cm); 586 NLA_PUT_U32(skb, IFLA_CAN_RESTART_MS, priv->restart_ms); 587 NLA_PUT(skb, IFLA_CAN_BITTIMING, 588 sizeof(priv->bittiming), &priv->bittiming); 589 NLA_PUT(skb, IFLA_CAN_CLOCK, sizeof(cm), &priv->clock); 590 if (priv->bittiming_const) 591 NLA_PUT(skb, IFLA_CAN_BITTIMING_CONST, 592 sizeof(*priv->bittiming_const), priv->bittiming_const); 593 594 return 0; 595 596nla_put_failure: 597 return -EMSGSIZE; 598} 599 600static int can_fill_xstats(struct sk_buff *skb, const struct net_device *dev) 601{ 602 struct can_priv *priv = netdev_priv(dev); 603 604 NLA_PUT(skb, IFLA_INFO_XSTATS, 605 sizeof(priv->can_stats), &priv->can_stats); 606 607 return 0; 608 609nla_put_failure: 610 return -EMSGSIZE; 611} 612 613static int can_newlink(struct net_device *dev, 614 struct nlattr *tb[], struct nlattr *data[]) 615{ 616 return -EOPNOTSUPP; 617} 618 619static struct rtnl_link_ops can_link_ops __read_mostly = { 620 .kind = "can", 621 .maxtype = IFLA_CAN_MAX, 622 .policy = can_policy, 623 .setup = can_setup, 624 .newlink = can_newlink, 625 .changelink = can_changelink, 626 .fill_info = can_fill_info, 627 .fill_xstats = can_fill_xstats, 628}; 629 630/* 631 * Register the CAN network device 632 */ 633int register_candev(struct net_device *dev) 634{ 635 dev->rtnl_link_ops = &can_link_ops; 636 return register_netdev(dev); 637} 638EXPORT_SYMBOL_GPL(register_candev); 639 640/* 641 * Unregister the CAN network device 642 */ 643void unregister_candev(struct net_device *dev) 644{ 645 unregister_netdev(dev); 646} 647EXPORT_SYMBOL_GPL(unregister_candev); 648 649static __init int can_dev_init(void) 650{ 651 int err; 652 653 err = rtnl_link_register(&can_link_ops); 654 if (!err) 655 printk(KERN_INFO MOD_DESC "\n"); 656 657 return err; 658} 659module_init(can_dev_init); 660 661static __exit void can_dev_exit(void) 662{ 663 rtnl_link_unregister(&can_link_ops); 664} 665module_exit(can_dev_exit); 666 667MODULE_ALIAS_RTNL_LINK("can"); 668