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 MODULE_DESCRIPTION("CAN netdevice library");
  31 MODULE_LICENSE("GPL v2");
  32 MODULE_AUTHOR("Marc Kleine-Budde <mkl@pengutronix.de>, "
  33               "Andrey Volkov <avolkov@varma-el.com>");
  34
  35 static int restart_ms = 0;
  36
  37 module_param(restart_ms, int, S_IRUGO | S_IWUSR);
  38
  39 MODULE_PARM_DESC(restart_ms, "Restart time after bus-off in ms (default 0)");
  40
  41
  42 /*
  43  * Abstract:
  44  *   Bit rate calculated with next formula:
  45  *   bitrate = frq/(brp*(1 + prop_seg+ phase_seg1 + phase_seg2))
  46  *
  47  *   This calc function based on work of Florian Hartwich and Armin Bassemi
  48  *   "The Configuration of the CAN Bit Timing"
  49  *   (http://www.semiconductors.bosch.de/pdf/CiA99Paper.pdf)
  50  *
  51  *  Parameters:
  52  *  [in]
  53  *    bittime_nsec - expected bit time in nanosecs
  54  *
  55  *  [out]
  56  *    bittime      - calculated time segments, for meaning of
  57  *                   each field read CAN standard.
  58  */
  59
  60 #define DEFAULT_MAX_BRP 64U
  61 #define DEFAULT_MAX_SJW 4U
  62
  63 /* All below values in tq units */
  64 #define MAX_BITTIME     25U
  65 #define MIN_BITTIME     8U
  66 #define MAX_PROP_SEG    8U
  67 #define MAX_PHASE_SEG1  8U
  68 #define MAX_PHASE_SEG2  8U
  69
  70 int can_calc_bittime(struct can_priv *can, u32 bitrate,
  71                      struct can_bittime_std *bittime)
  72 {
  73         int best_error = -1;    /* Ariphmetic error */
  74         int df, best_df = -1;   /* oscillator's tolerance range,
  75                                    greater is better */
  76         u32 quanta;             /* in tq units */
  77         u32 brp, phase_seg1, phase_seg2, sjw, prop_seg;
  78         u32 brp_min, brp_max, brp_expected;
  79         u64 tmp;
  80
  81         /* bitrate range [1baud,1MiB/s] */
  82         if (bitrate == 0 || bitrate > 1000000UL)
  83                 return -EINVAL;
  84
  85         tmp = (u64) can->can_sys_clock * 1000;
  86         do_div(tmp, bitrate);
  87         brp_expected = (u32) tmp;
  88
  89         brp_min = brp_expected / (1000 * MAX_BITTIME);
  90         if (brp_min == 0)
  91                 brp_min = 1;
  92         if (brp_min > can->max_brp)
  93                 return -ERANGE;
  94
  95         brp_max = (brp_expected + 500 * MIN_BITTIME) / (1000 * MIN_BITTIME);
  96         if (brp_max == 0)
  97                 brp_max = 1;
  98         if (brp_max > can->max_brp)
  99                 brp_max = can->max_brp;
 100
 101         for (brp = brp_min; brp <= brp_max; brp++) {
 102                 quanta = brp_expected / (brp * 1000);
 103                 if (quanta < MAX_BITTIME
 104                     && quanta * brp * 1000 != brp_expected)
 105                         quanta++;
 106                 if (quanta < MIN_BITTIME || quanta > MAX_BITTIME)
 107                         continue;
 108
 109                 phase_seg2 = min((quanta - 3) / 2, MAX_PHASE_SEG2);
 110                 for (sjw = can->max_sjw; sjw > 0; sjw--) {
 111                         for (; phase_seg2 > sjw; phase_seg2--) {
 112                                 u32 err1, err2;
 113                                 phase_seg1 =
 114                                     phase_seg2 % 2 ? phase_seg2 -
 115                                     1 : phase_seg2;
 116                                 prop_seg = quanta - 1 - phase_seg2 - phase_seg1;
 117                                 /*
 118                                  * FIXME: support of longer lines (i.e. bigger
 119                                  * prop_seg) is more prefered than support of
 120                                  * cheap oscillators (i.e. bigger
 121                                  * df/phase_seg1/phase_seg2)
 122                                  */
 123                                 if (prop_seg < phase_seg1)
 124                                         continue;
 125                                 if (prop_seg > MAX_PROP_SEG)
 126                                         goto next_brp;
 127
 128                                 err1 = phase_seg1 * brp * 500 * 1000 /
 129                                     (13 * brp_expected -
 130                                      phase_seg2 * brp * 1000);
 131                                 err2 = sjw * brp * 50 * 1000 / brp_expected;
 132
 133                                 df = min(err1, err2);
 134                                 if (df >= best_df) {
 135                                         unsigned error =
 136                                                 abs(brp_expected * 10 /
 137                                                     (brp * (1 + prop_seg +
 138                                                             phase_seg1 +
 139                                                             phase_seg2)) -
 140                                                     10000);
 141
 142                                         if (error > 10 || error > best_error)
 143                                                 continue;
 144
 145                                         if (error == best_error
 146                                             && prop_seg < bittime->prop_seg)
 147                                                 continue;
 148
 149                                         best_error = error;
 150                                         best_df = df;
 151                                         bittime->brp = brp;
 152                                         bittime->prop_seg = prop_seg;
 153                                         bittime->phase_seg1 = phase_seg1;
 154                                         bittime->phase_seg2 = phase_seg2;
 155                                         bittime->sjw = sjw;
 156                                         bittime->sam =
 157                                                 (bittime->phase_seg1 > 3);
 158                                 }
 159                         }
 160                 }
 161               next_brp:;
 162         }
 163
 164         if (best_error < 0)
 165                 return -EDOM;
 166         return 0;
 167 }
 168
 169 int can_set_bitrate(struct net_device *dev, u32 bitrate)
 170 {
 171         struct can_priv *priv = netdev_priv(dev);
 172         int err = -ENOTSUPP;
 173
 174         if (priv->state != CAN_STATE_STOPPED)
 175                 return -EBUSY;
 176
 177         if (priv->do_set_bittime) {
 178                 if (priv->do_set_bittime) {
 179                         struct can_bittime bittime;
 180                         err = can_calc_bittime(priv, bitrate, &bittime.std);
 181                         if (err)
 182                                 goto out;
 183                         bittime.type = CAN_BITTIME_STD;
 184                         err = priv->do_set_bittime(dev, &bittime);
 185                         if (!err) {
 186                                 priv->bitrate = bitrate;
 187                                 priv->bittime = bittime;
 188                         }
 189                 }
 190         }
 191 out:
 192         return err;
 193 }
 194 EXPORT_SYMBOL(can_set_bitrate);
 195
 196 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 197 static struct net_device_stats *can_get_stats(struct net_device *dev)
 198 {
 199         struct can_priv *priv = netdev_priv(dev);
 200
 201         return &priv->net_stats;
 202 }
 203 #endif
 204
 205 static void can_setup(struct net_device *dev)
 206 {
 207         dev->type = ARPHRD_CAN;
 208         dev->mtu = sizeof(struct can_frame);
 209         dev->hard_header_len = 0;
 210         dev->addr_len = 0;
 211         dev->tx_queue_len = 10;
 212
 213         /* New-style flags. */
 214         dev->flags = IFF_NOARP;
 215         dev->features = NETIF_F_NO_CSUM;
 216 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 217         dev->get_stats = can_get_stats;
 218 #endif
 219 }
 220
 221 /*
 222  * Function  alloc_candev
 223  *      Allocates and sets up an CAN device
 224  */
 225 struct net_device *alloc_candev(int sizeof_priv)
 226 {
 227         struct net_device *dev;
 228         struct can_priv *priv;
 229
 230         dev = alloc_netdev(sizeof_priv, "can%d", can_setup);
 231         if (!dev)
 232                 return NULL;
 233
 234         priv = netdev_priv(dev);
 235
 236         /* Default values can be overwritten by the device driver */
 237         priv->restart_ms = restart_ms;
 238         priv->bitrate = CAN_BITRATE_UNCONFIGURED;
 239         priv->state = CAN_STATE_STOPPED;
 240         priv->max_brp = DEFAULT_MAX_BRP;
 241         priv->max_sjw = DEFAULT_MAX_SJW;
 242         spin_lock_init(&priv->irq_lock);
 243
 244         init_timer(&priv->timer);
 245         priv->timer.expires = 0;
 246
 247         return dev;
 248 }
 249
 250 EXPORT_SYMBOL(alloc_candev);
 251
 252 void free_candev(struct net_device *dev)
 253 {
 254         free_netdev(dev);
 255 }
 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                         }
 311                 } else
 312                         skb_orphan(skb);
 313
 314                 skb->sk = srcsk;
 315
 316                 /* make settings for echo to reduce code in irq context */
 317                 skb->protocol = htons(ETH_P_CAN);
 318                 skb->pkt_type = PACKET_BROADCAST;
 319                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 320                 skb->dev = dev;
 321
 322                 /* save this skb for tx interrupt echo handling */
 323                 priv->echo_skb[idx] = skb;
 324         } else {
 325                 /* locking problem with netif_stop_queue() ?? */
 326                 printk(KERN_ERR "%s: %s: BUG! echo_skb is occupied!\n",
 327                        dev->name, __FUNCTION__);
 328                 kfree_skb(skb);
 329         }
 330 }
 331 EXPORT_SYMBOL(can_put_echo_skb);
 332
 333 void can_get_echo_skb(struct net_device *dev, int idx)
 334 {
 335         struct can_priv *priv = netdev_priv(dev);
 336
 337         if ((dev->flags & IFF_ECHO) && priv->echo_skb[idx]) {
 338                 netif_rx(priv->echo_skb[idx]);
 339                 priv->echo_skb[idx] = NULL;
 340         }
 341 }
 342 EXPORT_SYMBOL(can_get_echo_skb);
 343
 344 /*
 345  * CAN bus-off handling
 346  * FIXME: we need some synchronization
 347  */
 348 int can_restart_now(struct net_device *dev)
 349 {
 350         struct can_priv *priv = netdev_priv(dev);
 351         struct net_device_stats *stats = dev->get_stats(dev);
 352         struct sk_buff *skb;
 353         struct can_frame *cf;
 354         int err;
 355
 356         if (netif_carrier_ok(dev))
 357                 netif_carrier_off(dev);
 358
 359         /* Cancel restart in progress */
 360         if (priv->timer.expires) {
 361                 del_timer(&priv->timer);
 362                 priv->timer.expires = 0; /* mark inactive timer */
 363         }
 364
 365         can_flush_echo_skb(dev);
 366
 367         if ((err = priv->do_set_mode(dev, CAN_MODE_START)))
 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         return register_netdevice_notifier(&can_netdev_notifier);
 477 }
 478 module_init(can_dev_init);
 479
 480 static __exit void can_dev_exit(void)
 481 {
 482         unregister_netdevice_notifier(&can_netdev_notifier);
 483 }
 484 module_exit(can_dev_exit);