kernel/2.6/drivers/net/can/dev.c

   1 /*
   2  * $Id$
   3  *
   4  * Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
   5  * Copyright (C) 2006 Andrey Volkov, Varma Electronics
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the version 2 of the GNU General Public License
   9  * as published by the Free Software Foundation
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/rtnetlink.h>
  25 #include <linux/can.h>
  26 #include <linux/can/dev.h>
  27
  28 #include "sysfs.h"
  29
  30 #define MOD_DESC "CAN netdevice library"
  31
  32 MODULE_DESCRIPTION(MOD_DESC);
  33 MODULE_LICENSE("GPL v2");
  34 MODULE_AUTHOR("Marc Kleine-Budde <mkl@pengutronix.de>, "
  35               "Andrey Volkov <avolkov@varma-el.com>");
  36
  37 static int restart_ms;
  38
  39 module_param(restart_ms, int, S_IRUGO | S_IWUSR);
  40
  41 MODULE_PARM_DESC(restart_ms, "Restart time after bus-off in ms (default 0)");
  42
  43
  44 /*
  45  * Abstract:
  46  *   Bit rate calculated with next formula:
  47  *   bitrate = frq/(brp*(1 + prop_seg+ phase_seg1 + phase_seg2))
  48  *
  49  *   This calc function based on work of Florian Hartwich and Armin Bassemi
  50  *   "The Configuration of the CAN Bit Timing"
  51  *   (http://www.semiconductors.bosch.de/pdf/CiA99Paper.pdf)
  52  *
  53  *  Parameters:
  54  *  [in]
  55  *    bittime_nsec - expected bit time in nanosecs
  56  *
  57  *  [out]
  58  *    bittime      - calculated time segments, for meaning of
  59  *                   each field read CAN standard.
  60  */
  61
  62 #define DEFAULT_MAX_BRP 64U
  63 #define DEFAULT_MAX_SJW 4U
  64
  65 /* All below values in tq units */
  66 #define MAX_BITTIME     25U
  67 #define MIN_BITTIME     8U
  68 #define MAX_PROP_SEG    8U
  69 #define MAX_PHASE_SEG1  8U
  70 #define MAX_PHASE_SEG2  8U
  71
  72 int can_calc_bittime(struct can_priv *can, u32 bitrate,
  73                      struct can_bittime_std *bittime)
  74 {
  75         int best_error = -1;    /* Ariphmetic error */
  76         int df, best_df = -1;   /* oscillator's tolerance range,
  77                                    greater is better */
  78         u32 quanta;             /* in tq units */
  79         u32 brp, phase_seg1, phase_seg2, sjw, prop_seg;
  80         u32 brp_min, brp_max, brp_expected;
  81         u64 tmp;
  82
  83         /* bitrate range [1baud,1MiB/s] */
  84         if (bitrate == 0 || bitrate > 1000000UL)
  85                 return -EINVAL;
  86
  87         tmp = (u64) can->can_sys_clock * 1000;
  88         do_div(tmp, bitrate);
  89         brp_expected = (u32) tmp;
  90
  91         brp_min = brp_expected / (1000 * MAX_BITTIME);
  92         if (brp_min == 0)
  93                 brp_min = 1;
  94         if (brp_min > can->max_brp)
  95                 return -ERANGE;
  96
  97         brp_max = (brp_expected + 500 * MIN_BITTIME) / (1000 * MIN_BITTIME);
  98         if (brp_max == 0)
  99                 brp_max = 1;
 100         if (brp_max > can->max_brp)
 101                 brp_max = can->max_brp;
 102
 103         for (brp = brp_min; brp <= brp_max; brp++) {
 104                 quanta = brp_expected / (brp * 1000);
 105                 if (quanta < MAX_BITTIME
 106                     && quanta * brp * 1000 != brp_expected)
 107                         quanta++;
 108                 if (quanta < MIN_BITTIME || quanta > MAX_BITTIME)
 109                         continue;
 110
 111                 phase_seg2 = min((quanta - 3) / 2, MAX_PHASE_SEG2);
 112                 for (sjw = can->max_sjw; sjw > 0; sjw--) {
 113                         for (; phase_seg2 > sjw; phase_seg2--) {
 114                                 u32 err1, err2;
 115                                 phase_seg1 =
 116                                     phase_seg2 % 2 ? phase_seg2 -
 117                                     1 : phase_seg2;
 118                                 prop_seg = quanta - 1 - phase_seg2 - phase_seg1;
 119                                 /*
 120                                  * FIXME: support of longer lines (i.e. bigger
 121                                  * prop_seg) is more prefered than support of
 122                                  * cheap oscillators (i.e. bigger
 123                                  * df/phase_seg1/phase_seg2)
 124                                  */
 125                                 if (prop_seg < phase_seg1)
 126                                         continue;
 127                                 if (prop_seg > MAX_PROP_SEG)
 128                                         goto next_brp;
 129
 130                                 err1 = phase_seg1 * brp * 500 * 1000 /
 131                                     (13 * brp_expected -
 132                                      phase_seg2 * brp * 1000);
 133                                 err2 = sjw * brp * 50 * 1000 / brp_expected;
 134
 135                                 df = min(err1, err2);
 136                                 if (df >= best_df) {
 137                                         unsigned error =
 138                                                 abs(brp_expected * 10 /
 139                                                     (brp * (1 + prop_seg +
 140                                                             phase_seg1 +
 141                                                             phase_seg2)) -
 142                                                     10000);
 143
 144                                         if (error > 10 || error > best_error)
 145                                                 continue;
 146
 147                                         if (error == best_error
 148                                             && prop_seg < bittime->prop_seg)
 149                                                 continue;
 150
 151                                         best_error = error;
 152                                         best_df = df;
 153                                         bittime->brp = brp;
 154                                         bittime->prop_seg = prop_seg;
 155                                         bittime->phase_seg1 = phase_seg1;
 156                                         bittime->phase_seg2 = phase_seg2;
 157                                         bittime->sjw = sjw;
 158                                         bittime->sam =
 159                                                 (bittime->phase_seg1 > 3);
 160                                 }
 161                         }
 162                 }
 163 next_brp:;
 164         }
 165
 166         if (best_error < 0)
 167                 return -EDOM;
 168         return 0;
 169 }
 170
 171 int can_set_bitrate(struct net_device *dev, u32 bitrate)
 172 {
 173         struct can_priv *priv = netdev_priv(dev);
 174         int err = -ENOTSUPP;
 175
 176         if (priv->state != CAN_STATE_STOPPED)
 177                 return -EBUSY;
 178
 179         if (priv->do_set_bittime) {
 180                 if (priv->do_set_bittime) {
 181                         struct can_bittime bittime;
 182                         err = can_calc_bittime(priv, bitrate, &bittime.std);
 183                         if (err)
 184                                 goto out;
 185                         bittime.type = CAN_BITTIME_STD;
 186                         err = priv->do_set_bittime(dev, &bittime);
 187                         if (!err) {
 188                                 priv->bitrate = bitrate;
 189                                 priv->bittime = bittime;
 190                         }
 191                 }
 192         }
 193 out:
 194         return err;
 195 }
 196 EXPORT_SYMBOL(can_set_bitrate);
 197
 198 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 199 static struct net_device_stats *can_get_stats(struct net_device *dev)
 200 {
 201         struct can_priv *priv = netdev_priv(dev);
 202
 203         return &priv->net_stats;
 204 }
 205 #endif
 206
 207 static void can_setup(struct net_device *dev)
 208 {
 209         dev->type = ARPHRD_CAN;
 210         dev->mtu = sizeof(struct can_frame);
 211         dev->hard_header_len = 0;
 212         dev->addr_len = 0;
 213         dev->tx_queue_len = 10;
 214
 215         /* New-style flags. */
 216         dev->flags = IFF_NOARP;
 217         dev->features = NETIF_F_NO_CSUM;
 218 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 219         dev->get_stats = can_get_stats;
 220 #endif
 221 }
 222
 223 /*
 224  * Function  alloc_candev
 225  *      Allocates and sets up an CAN device
 226  */
 227 struct net_device *alloc_candev(int sizeof_priv)
 228 {
 229         struct net_device *dev;
 230         struct can_priv *priv;
 231
 232         dev = alloc_netdev(sizeof_priv, "can%d", can_setup);
 233         if (!dev)
 234                 return NULL;
 235
 236         priv = netdev_priv(dev);
 237
 238         /* Default values can be overwritten by the device driver */
 239         priv->restart_ms = restart_ms;
 240         priv->bitrate = CAN_BITRATE_UNCONFIGURED;
 241         priv->state = CAN_STATE_STOPPED;
 242         priv->max_brp = DEFAULT_MAX_BRP;
 243         priv->max_sjw = DEFAULT_MAX_SJW;
 244         spin_lock_init(&priv->irq_lock);
 245
 246         init_timer(&priv->timer);
 247         priv->timer.expires = 0;
 248
 249         return dev;
 250 }
 251 EXPORT_SYMBOL(alloc_candev);
 252
 253 void free_candev(struct net_device *dev)
 254 {
 255         free_netdev(dev);
 256 }
 257 EXPORT_SYMBOL(free_candev);
 258
 259 /*
 260  * Local echo of CAN messages
 261  *
 262  * CAN network devices *should* support a local echo functionality
 263  * (see Documentation/networking/can.txt). To test the handling of CAN
 264  * interfaces that do not support the local echo both driver types are
 265  * implemented. In the case that the driver does not support the echo
 266  * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
 267  * to perform the echo as a fallback solution.
 268  */
 269
 270 void can_flush_echo_skb(struct net_device *dev)
 271 {
 272         struct can_priv *priv = netdev_priv(dev);
 273 #ifdef FIXME
 274         struct net_device_stats *stats = dev->get_stats(dev);
 275 #endif
 276         int i;
 277
 278         for (i = 0; i < CAN_ECHO_SKB_MAX; i++) {
 279                 if (priv->echo_skb[i]) {
 280                         kfree_skb(priv->echo_skb[i]);
 281                         priv->echo_skb[i] = NULL;
 282 #ifdef FIXME
 283                         stats->tx_dropped++;
 284                         stats->tx_aborted_errors++;
 285 #endif
 286                 }
 287         }
 288 }
 289
 290 void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, int idx)
 291 {
 292         struct can_priv *priv = netdev_priv(dev);
 293
 294         /* set flag whether this packet has to be looped back */
 295         if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK) {
 296                 kfree_skb(skb);
 297                 return;
 298         }
 299
 300         if (!priv->echo_skb[idx]) {
 301                 struct sock *srcsk = skb->sk;
 302
 303                 if (atomic_read(&skb->users) != 1) {
 304                         struct sk_buff *old_skb = skb;
 305
 306                         skb = skb_clone(old_skb, GFP_ATOMIC);
 307                         kfree_skb(old_skb);
 308                         if (!skb)
 309                                 return;
 310                 } else
 311                         skb_orphan(skb);
 312
 313                 skb->sk = srcsk;
 314
 315                 /* make settings for echo to reduce code in irq context */
 316                 skb->protocol = htons(ETH_P_CAN);
 317                 skb->pkt_type = PACKET_BROADCAST;
 318                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 319                 skb->dev = dev;
 320
 321                 /* save this skb for tx interrupt echo handling */
 322                 priv->echo_skb[idx] = skb;
 323         } else {
 324                 /* locking problem with netif_stop_queue() ?? */
 325                 printk(KERN_ERR "%s: %s: BUG! echo_skb is occupied!\n",
 326                        dev->name, __func__);
 327                 kfree_skb(skb);
 328         }
 329 }
 330 EXPORT_SYMBOL(can_put_echo_skb);
 331
 332 void can_get_echo_skb(struct net_device *dev, int idx)
 333 {
 334         struct can_priv *priv = netdev_priv(dev);
 335
 336         if ((dev->flags & IFF_ECHO) && priv->echo_skb[idx]) {
 337                 netif_rx(priv->echo_skb[idx]);
 338                 priv->echo_skb[idx] = NULL;
 339         }
 340 }
 341 EXPORT_SYMBOL(can_get_echo_skb);
 342
 343 /*
 344  * CAN bus-off handling
 345  * FIXME: we need some synchronization
 346  */
 347 int can_restart_now(struct net_device *dev)
 348 {
 349         struct can_priv *priv = netdev_priv(dev);
 350         struct net_device_stats *stats = dev->get_stats(dev);
 351         struct sk_buff *skb;
 352         struct can_frame *cf;
 353         int err;
 354
 355         if (netif_carrier_ok(dev))
 356                 netif_carrier_off(dev);
 357
 358         /* Cancel restart in progress */
 359         if (priv->timer.expires) {
 360                 del_timer(&priv->timer);
 361                 priv->timer.expires = 0; /* mark inactive timer */
 362         }
 363
 364         can_flush_echo_skb(dev);
 365
 366         err = priv->do_set_mode(dev, CAN_MODE_START);
 367         if (err)
 368                 return err;
 369
 370         netif_carrier_on(dev);
 371
 372         priv->can_stats.restarts++;
 373
 374         /* send restart message upstream */
 375         skb = dev_alloc_skb(sizeof(struct can_frame));
 376         if (skb == NULL)
 377                 return -ENOMEM;
 378         skb->dev = dev;
 379         skb->protocol = htons(ETH_P_CAN);
 380         cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
 381         memset(cf, 0, sizeof(struct can_frame));
 382         cf->can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED;
 383         cf->can_dlc = CAN_ERR_DLC;
 384
 385         netif_rx(skb);
 386
 387         dev->last_rx = jiffies;
 388         stats->rx_packets++;
 389         stats->rx_bytes += cf->can_dlc;
 390
 391         return 0;
 392 }
 393
 394 static void can_restart_after(unsigned long data)
 395 {
 396         struct net_device *dev = (struct net_device *)data;
 397         struct can_priv *priv = netdev_priv(dev);
 398
 399         priv->timer.expires = 0; /* mark inactive timer */
 400         can_restart_now(dev);
 401 }
 402
 403 void can_bus_off(struct net_device *dev)
 404 {
 405         struct can_priv *priv = netdev_priv(dev);
 406
 407         netif_carrier_off(dev);
 408
 409         if (priv->restart_ms > 0 && !priv->timer.expires) {
 410
 411                 priv->timer.function = can_restart_after;
 412                 priv->timer.data = (unsigned long)dev;
 413                 priv->timer.expires =
 414                         jiffies + (priv->restart_ms * HZ) / 1000;
 415                 add_timer(&priv->timer);
 416         }
 417 }
 418 EXPORT_SYMBOL(can_bus_off);
 419
 420 void can_close_cleanup(struct net_device *dev)
 421 {
 422         struct can_priv *priv = netdev_priv(dev);
 423
 424         if (priv->timer.expires) {
 425                 del_timer(&priv->timer);
 426                 priv->timer.expires = 0;
 427         }
 428
 429         can_flush_echo_skb(dev);
 430 }
 431 EXPORT_SYMBOL(can_close_cleanup);
 432
 433 static int can_netdev_notifier_call(struct notifier_block *nb,
 434                                     unsigned long state,
 435                                     void *ndev)
 436 {
 437         struct net_device *dev = ndev;
 438         struct can_priv *priv;
 439
 440         if (dev->type != ARPHRD_CAN)
 441                 return 0;
 442
 443         priv = netdev_priv(dev);
 444
 445         /* software CAN devices like 'vcan' do not have private data */
 446         if (!priv)
 447                 return 0;
 448
 449         switch (state) {
 450         case NETDEV_REGISTER:
 451                 /* set default bit timing */
 452                 if (priv->do_set_bittime &&
 453                     priv->bitrate == CAN_BITRATE_UNCONFIGURED) {
 454                         if (can_set_bitrate(dev, CAN_BITRATE_DEFAULT))
 455                                 dev_err(ND2D(dev), "failed to set bitrate\n");
 456                 }
 457 #ifdef CONFIG_SYSFS
 458                 can_create_sysfs(dev);
 459 #endif
 460                 break;
 461         case NETDEV_UNREGISTER:
 462 #ifdef CONFIG_SYSFS
 463                 can_remove_sysfs(dev);
 464 #endif
 465                 break;
 466         }
 467         return 0;
 468 }
 469
 470 static struct notifier_block can_netdev_notifier = {
 471         .notifier_call = can_netdev_notifier_call,
 472 };
 473
 474 static __init int can_dev_init(void)
 475 {
 476         printk(KERN_INFO MOD_DESC "\n");
 477
 478         return register_netdevice_notifier(&can_netdev_notifier);
 479 }
 480 module_init(can_dev_init);
 481
 482 static __exit void can_dev_exit(void)
 483 {
 484         unregister_netdevice_notifier(&can_netdev_notifier);
 485 }
 486 module_exit(can_dev_exit);