drivers/w1/w1.c

   1 /*
   2  *      w1.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   5  *
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  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.
  16  *
  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
  20  */
  21
  22 #include <linux/delay.h>
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/list.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/timer.h>
  30 #include <linux/device.h>
  31 #include <linux/slab.h>
  32 #include <linux/sched.h>
  33
  34 #include <asm/atomic.h>
  35
  36 #include "w1.h"
  37 #include "w1_io.h"
  38 #include "w1_log.h"
  39 #include "w1_int.h"
  40 #include "w1_family.h"
  41 #include "w1_netlink.h"
  42
  43 MODULE_LICENSE("GPL");
  44 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  45 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
  46
  47 static int w1_timeout = 10;
  48 int w1_max_slave_count = 10;
  49 int w1_max_slave_ttl = 10;
  50
  51 module_param_named(timeout, w1_timeout, int, 0);
  52 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
  53 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
  54
  55 DEFINE_SPINLOCK(w1_mlock);
  56 LIST_HEAD(w1_masters);
  57
  58 static pid_t control_thread;
  59 static int control_needs_exit;
  60 static DECLARE_COMPLETION(w1_control_complete);
  61
  62 static int w1_master_match(struct device *dev, struct device_driver *drv)
  63 {
  64         return 1;
  65 }
  66
  67 static int w1_master_probe(struct device *dev)
  68 {
  69         return -ENODEV;
  70 }
  71
  72 static int w1_master_remove(struct device *dev)
  73 {
  74         return 0;
  75 }
  76
  77 static void w1_master_release(struct device *dev)
  78 {
  79         struct w1_master *md = container_of(dev, struct w1_master, dev);
  80
  81         complete(&md->dev_released);
  82 }
  83
  84 static void w1_slave_release(struct device *dev)
  85 {
  86         struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
  87
  88         complete(&sl->dev_released);
  89 }
  90
  91 static ssize_t w1_default_read_name(struct device *dev, struct device_attribute *attr, char *buf)
  92 {
  93         return sprintf(buf, "No family registered.\n");
  94 }
  95
  96 static ssize_t w1_default_read_bin(struct kobject *kobj, char *buf, loff_t off,
  97                      size_t count)
  98 {
  99         return sprintf(buf, "No family registered.\n");
 100 }
 101
 102 static struct device_attribute w1_slave_attribute =
 103         __ATTR(name, S_IRUGO, w1_default_read_name, NULL);
 104
 105 static struct bin_attribute w1_slave_bin_attribute = {
 106         .attr = {
 107                 .name = "w1_slave",
 108                 .mode = S_IRUGO,
 109                 .owner = THIS_MODULE,
 110         },
 111         .size = W1_SLAVE_DATA_SIZE,
 112         .read = &w1_default_read_bin,
 113 };
 114
 115
 116 static struct bus_type w1_bus_type = {
 117         .name = "w1",
 118         .match = w1_master_match,
 119 };
 120
 121 struct device_driver w1_driver = {
 122         .name = "w1_driver",
 123         .bus = &w1_bus_type,
 124         .probe = w1_master_probe,
 125         .remove = w1_master_remove,
 126 };
 127
 128 struct device w1_device = {
 129         .parent = NULL,
 130         .bus = &w1_bus_type,
 131         .bus_id = "w1 bus master",
 132         .driver = &w1_driver,
 133         .release = &w1_master_release
 134 };
 135
 136 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
 137 {
 138         struct w1_master *md = container_of(dev, struct w1_master, dev);
 139         ssize_t count;
 140
 141         if (down_interruptible (&md->mutex))
 142                 return -EBUSY;
 143
 144         count = sprintf(buf, "%s\n", md->name);
 145
 146         up(&md->mutex);
 147
 148         return count;
 149 }
 150
 151 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
 152 {
 153         struct w1_master *md = container_of(dev, struct w1_master, dev);
 154         ssize_t count;
 155
 156         if (down_interruptible(&md->mutex))
 157                 return -EBUSY;
 158
 159         count = sprintf(buf, "0x%p\n", md->bus_master);
 160
 161         up(&md->mutex);
 162         return count;
 163 }
 164
 165 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
 166 {
 167         ssize_t count;
 168         count = sprintf(buf, "%d\n", w1_timeout);
 169         return count;
 170 }
 171
 172 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 173 {
 174         struct w1_master *md = container_of(dev, struct w1_master, dev);
 175         ssize_t count;
 176
 177         if (down_interruptible(&md->mutex))
 178                 return -EBUSY;
 179
 180         count = sprintf(buf, "%d\n", md->max_slave_count);
 181
 182         up(&md->mutex);
 183         return count;
 184 }
 185
 186 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
 187 {
 188         struct w1_master *md = container_of(dev, struct w1_master, dev);
 189         ssize_t count;
 190
 191         if (down_interruptible(&md->mutex))
 192                 return -EBUSY;
 193
 194         count = sprintf(buf, "%lu\n", md->attempts);
 195
 196         up(&md->mutex);
 197         return count;
 198 }
 199
 200 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 201 {
 202         struct w1_master *md = container_of(dev, struct w1_master, dev);
 203         ssize_t count;
 204
 205         if (down_interruptible(&md->mutex))
 206                 return -EBUSY;
 207
 208         count = sprintf(buf, "%d\n", md->slave_count);
 209
 210         up(&md->mutex);
 211         return count;
 212 }
 213
 214 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
 215 {
 216         struct w1_master *md = container_of(dev, struct w1_master, dev);
 217         int c = PAGE_SIZE;
 218
 219         if (down_interruptible(&md->mutex))
 220                 return -EBUSY;
 221
 222         if (md->slave_count == 0)
 223                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
 224         else {
 225                 struct list_head *ent, *n;
 226                 struct w1_slave *sl;
 227
 228                 list_for_each_safe(ent, n, &md->slist) {
 229                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 230
 231                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
 232                 }
 233         }
 234
 235         up(&md->mutex);
 236
 237         return PAGE_SIZE - c;
 238 }
 239
 240 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
 241         struct device_attribute w1_master_attribute_##_name =   \
 242                 __ATTR(w1_master_##_name, _mode,                \
 243                        w1_master_attribute_show_##_name, NULL)
 244
 245 static W1_MASTER_ATTR_RO(name, S_IRUGO);
 246 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
 247 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
 248 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
 249 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
 250 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
 251 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
 252
 253 static struct attribute *w1_master_default_attrs[] = {
 254         &w1_master_attribute_name.attr,
 255         &w1_master_attribute_slaves.attr,
 256         &w1_master_attribute_slave_count.attr,
 257         &w1_master_attribute_max_slave_count.attr,
 258         &w1_master_attribute_attempts.attr,
 259         &w1_master_attribute_timeout.attr,
 260         &w1_master_attribute_pointer.attr,
 261         NULL
 262 };
 263
 264 static struct attribute_group w1_master_defattr_group = {
 265         .attrs = w1_master_default_attrs,
 266 };
 267
 268 int w1_create_master_attributes(struct w1_master *master)
 269 {
 270         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
 271 }
 272
 273 void w1_destroy_master_attributes(struct w1_master *master)
 274 {
 275         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
 276 }
 277
 278 static int __w1_attach_slave_device(struct w1_slave *sl)
 279 {
 280         int err;
 281
 282         sl->dev.parent = &sl->master->dev;
 283         sl->dev.driver = sl->master->driver;
 284         sl->dev.bus = &w1_bus_type;
 285         sl->dev.release = &w1_slave_release;
 286
 287         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
 288                  "%02x-%012llx",
 289                  (unsigned int) sl->reg_num.family,
 290                  (unsigned long long) sl->reg_num.id);
 291         snprintf(&sl->name[0], sizeof(sl->name),
 292                  "%02x-%012llx",
 293                  (unsigned int) sl->reg_num.family,
 294                  (unsigned long long) sl->reg_num.id);
 295
 296         dev_dbg(&sl->dev, "%s: registering %s.\n", __func__,
 297                 &sl->dev.bus_id[0]);
 298
 299         err = device_register(&sl->dev);
 300         if (err < 0) {
 301                 dev_err(&sl->dev,
 302                         "Device registration [%s] failed. err=%d\n",
 303                         sl->dev.bus_id, err);
 304                 return err;
 305         }
 306
 307         memcpy(&sl->attr_bin, &w1_slave_bin_attribute, sizeof(sl->attr_bin));
 308         memcpy(&sl->attr_name, &w1_slave_attribute, sizeof(sl->attr_name));
 309
 310         sl->attr_bin.read = sl->family->fops->rbin;
 311         sl->attr_name.show = sl->family->fops->rname;
 312
 313         err = device_create_file(&sl->dev, &sl->attr_name);
 314         if (err < 0) {
 315                 dev_err(&sl->dev,
 316                         "sysfs file creation for [%s] failed. err=%d\n",
 317                         sl->dev.bus_id, err);
 318                 device_unregister(&sl->dev);
 319                 return err;
 320         }
 321
 322         err = sysfs_create_bin_file(&sl->dev.kobj, &sl->attr_bin);
 323         if (err < 0) {
 324                 dev_err(&sl->dev,
 325                         "sysfs file creation for [%s] failed. err=%d\n",
 326                         sl->dev.bus_id, err);
 327                 device_remove_file(&sl->dev, &sl->attr_name);
 328                 device_unregister(&sl->dev);
 329                 return err;
 330         }
 331
 332         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
 333
 334         return 0;
 335 }
 336
 337 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
 338 {
 339         struct w1_slave *sl;
 340         struct w1_family *f;
 341         int err;
 342         struct w1_netlink_msg msg;
 343
 344         sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
 345         if (!sl) {
 346                 dev_err(&dev->dev,
 347                          "%s: failed to allocate new slave device.\n",
 348                          __func__);
 349                 return -ENOMEM;
 350         }
 351
 352         memset(sl, 0, sizeof(*sl));
 353
 354         sl->owner = THIS_MODULE;
 355         sl->master = dev;
 356         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 357
 358         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
 359         atomic_set(&sl->refcnt, 0);
 360         init_completion(&sl->dev_released);
 361
 362         spin_lock(&w1_flock);
 363         f = w1_family_registered(rn->family);
 364         if (!f) {
 365                 spin_unlock(&w1_flock);
 366                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
 367                           rn->family, rn->family,
 368                           (unsigned long long)rn->id, rn->crc);
 369                 kfree(sl);
 370                 return -ENODEV;
 371         }
 372         __w1_family_get(f);
 373         spin_unlock(&w1_flock);
 374
 375         sl->family = f;
 376
 377
 378         err = __w1_attach_slave_device(sl);
 379         if (err < 0) {
 380                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
 381                          sl->name);
 382                 w1_family_put(sl->family);
 383                 kfree(sl);
 384                 return err;
 385         }
 386
 387         sl->ttl = dev->slave_ttl;
 388         dev->slave_count++;
 389
 390         memcpy(&msg.id.id, rn, sizeof(msg.id.id));
 391         msg.type = W1_SLAVE_ADD;
 392         w1_netlink_send(dev, &msg);
 393
 394         return 0;
 395 }
 396
 397 static void w1_slave_detach(struct w1_slave *sl)
 398 {
 399         struct w1_netlink_msg msg;
 400
 401         dev_info(&sl->dev, "%s: detaching %s.\n", __func__, sl->name);
 402
 403         while (atomic_read(&sl->refcnt)) {
 404                 printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n",
 405                                 sl->name, atomic_read(&sl->refcnt));
 406
 407                 if (msleep_interruptible(1000))
 408                         flush_signals(current);
 409         }
 410
 411         sysfs_remove_bin_file (&sl->dev.kobj, &sl->attr_bin);
 412         device_remove_file(&sl->dev, &sl->attr_name);
 413         device_unregister(&sl->dev);
 414         w1_family_put(sl->family);
 415
 416         memcpy(&msg.id.id, &sl->reg_num, sizeof(msg.id.id));
 417         msg.type = W1_SLAVE_REMOVE;
 418         w1_netlink_send(sl->master, &msg);
 419 }
 420
 421 static struct w1_master *w1_search_master(unsigned long data)
 422 {
 423         struct w1_master *dev;
 424         int found = 0;
 425
 426         spin_lock_bh(&w1_mlock);
 427         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 428                 if (dev->bus_master->data == data) {
 429                         found = 1;
 430                         atomic_inc(&dev->refcnt);
 431                         break;
 432                 }
 433         }
 434         spin_unlock_bh(&w1_mlock);
 435
 436         return (found)?dev:NULL;
 437 }
 438
 439 static void w1_slave_found(unsigned long data, u64 rn)
 440 {
 441         int slave_count;
 442         struct w1_slave *sl;
 443         struct list_head *ent;
 444         struct w1_reg_num *tmp;
 445         int family_found = 0;
 446         struct w1_master *dev;
 447
 448         dev = w1_search_master(data);
 449         if (!dev) {
 450                 printk(KERN_ERR "Failed to find w1 master device for data %08lx, it is impossible.\n",
 451                                 data);
 452                 return;
 453         }
 454
 455         tmp = (struct w1_reg_num *) &rn;
 456
 457         slave_count = 0;
 458         list_for_each(ent, &dev->slist) {
 459
 460                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 461
 462                 if (sl->reg_num.family == tmp->family &&
 463                     sl->reg_num.id == tmp->id &&
 464                     sl->reg_num.crc == tmp->crc) {
 465                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 466                         break;
 467                 } else if (sl->reg_num.family == tmp->family) {
 468                         family_found = 1;
 469                         break;
 470                 }
 471
 472                 slave_count++;
 473         }
 474
 475         rn = cpu_to_le64(rn);
 476
 477         if (slave_count == dev->slave_count &&
 478                 rn && ((le64_to_cpu(rn) >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn, 7)) {
 479                 w1_attach_slave_device(dev, tmp);
 480         }
 481
 482         atomic_dec(&dev->refcnt);
 483 }
 484
 485 /**
 486  * Performs a ROM Search & registers any devices found.
 487  * The 1-wire search is a simple binary tree search.
 488  * For each bit of the address, we read two bits and write one bit.
 489  * The bit written will put to sleep all devies that don't match that bit.
 490  * When the two reads differ, the direction choice is obvious.
 491  * When both bits are 0, we must choose a path to take.
 492  * When we can scan all 64 bits without having to choose a path, we are done.
 493  *
 494  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
 495  *
 496  * @dev        The master device to search
 497  * @cb         Function to call when a device is found
 498  */
 499 void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
 500 {
 501         u64 last_rn, rn, tmp64;
 502         int i, slave_count = 0;
 503         int last_zero, last_device;
 504         int search_bit, desc_bit;
 505         u8  triplet_ret = 0;
 506
 507         search_bit = 0;
 508         rn = last_rn = 0;
 509         last_device = 0;
 510         last_zero = -1;
 511
 512         desc_bit = 64;
 513
 514         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
 515                 last_rn = rn;
 516                 rn = 0;
 517
 518                 /*
 519                  * Reset bus and all 1-wire device state machines
 520                  * so they can respond to our requests.
 521                  *
 522                  * Return 0 - device(s) present, 1 - no devices present.
 523                  */
 524                 if (w1_reset_bus(dev)) {
 525                         dev_info(&dev->dev, "No devices present on the wire.\n");
 526                         break;
 527                 }
 528
 529                 /* Start the search */
 530                 w1_write_8(dev, W1_SEARCH);
 531                 for (i = 0; i < 64; ++i) {
 532                         /* Determine the direction/search bit */
 533                         if (i == desc_bit)
 534                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
 535                         else if (i > desc_bit)
 536                                 search_bit = 0;   /* take the 0 path on the next branch */
 537                         else
 538                                 search_bit = ((last_rn >> i) & 0x1);
 539
 540                         /** Read two bits and write one bit */
 541                         triplet_ret = w1_triplet(dev, search_bit);
 542
 543                         /* quit if no device responded */
 544                         if ( (triplet_ret & 0x03) == 0x03 )
 545                                 break;
 546
 547                         /* If both directions were valid, and we took the 0 path... */
 548                         if (triplet_ret == 0)
 549                                 last_zero = i;
 550
 551                         /* extract the direction taken & update the device number */
 552                         tmp64 = (triplet_ret >> 2);
 553                         rn |= (tmp64 << i);
 554                 }
 555
 556                 if ( (triplet_ret & 0x03) != 0x03 ) {
 557                         if ( (desc_bit == last_zero) || (last_zero < 0))
 558                                 last_device = 1;
 559                         desc_bit = last_zero;
 560                         cb(dev->bus_master->data, rn);
 561                 }
 562         }
 563 }
 564
 565 static int w1_control(void *data)
 566 {
 567         struct w1_slave *sl, *sln;
 568         struct w1_master *dev, *n;
 569         int err, have_to_wait = 0;
 570
 571         daemonize("w1_control");
 572         allow_signal(SIGTERM);
 573
 574         while (!control_needs_exit || have_to_wait) {
 575                 have_to_wait = 0;
 576
 577                 try_to_freeze(PF_FREEZE);
 578                 msleep_interruptible(w1_timeout * 1000);
 579
 580                 if (signal_pending(current))
 581                         flush_signals(current);
 582
 583                 list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
 584                         if (!control_needs_exit && !dev->need_exit)
 585                                 continue;
 586                         /*
 587                          * Little race: we can create thread but not set the flag.
 588                          * Get a chance for external process to set flag up.
 589                          */
 590                         if (!dev->initialized) {
 591                                 have_to_wait = 1;
 592                                 continue;
 593                         }
 594
 595                         spin_lock_bh(&w1_mlock);
 596                         list_del(&dev->w1_master_entry);
 597                         spin_unlock_bh(&w1_mlock);
 598
 599                         if (control_needs_exit) {
 600                                 dev->need_exit = 1;
 601
 602                                 err = kill_proc(dev->kpid, SIGTERM, 1);
 603                                 if (err)
 604                                         dev_err(&dev->dev,
 605                                                  "Failed to send signal to w1 kernel thread %d.\n",
 606                                                  dev->kpid);
 607                         }
 608
 609                         wait_for_completion(&dev->dev_exited);
 610
 611                         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 612                                 list_del(&sl->w1_slave_entry);
 613
 614                                 w1_slave_detach(sl);
 615                                 kfree(sl);
 616                         }
 617                         w1_destroy_master_attributes(dev);
 618                         atomic_dec(&dev->refcnt);
 619                 }
 620         }
 621
 622         complete_and_exit(&w1_control_complete, 0);
 623 }
 624
 625 int w1_process(void *data)
 626 {
 627         struct w1_master *dev = (struct w1_master *) data;
 628         struct w1_slave *sl, *sln;
 629
 630         daemonize("%s", dev->name);
 631         allow_signal(SIGTERM);
 632
 633         while (!dev->need_exit) {
 634                 try_to_freeze(PF_FREEZE);
 635                 msleep_interruptible(w1_timeout * 1000);
 636
 637                 if (signal_pending(current))
 638                         flush_signals(current);
 639
 640                 if (dev->need_exit)
 641                         break;
 642
 643                 if (!dev->initialized)
 644                         continue;
 645
 646                 if (down_interruptible(&dev->mutex))
 647                         continue;
 648
 649                 list_for_each_entry(sl, &dev->slist, w1_slave_entry)
 650                                 clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 651
 652                 w1_search_devices(dev, w1_slave_found);
 653
 654                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 655                         if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
 656                                 list_del (&sl->w1_slave_entry);
 657
 658                                 w1_slave_detach (sl);
 659                                 kfree (sl);
 660
 661                                 dev->slave_count--;
 662                         } else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
 663                                 sl->ttl = dev->slave_ttl;
 664                 }
 665                 up(&dev->mutex);
 666         }
 667
 668         atomic_dec(&dev->refcnt);
 669         complete_and_exit(&dev->dev_exited, 0);
 670
 671         return 0;
 672 }
 673
 674 static int w1_init(void)
 675 {
 676         int retval;
 677
 678         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
 679
 680         retval = bus_register(&w1_bus_type);
 681         if (retval) {
 682                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
 683                 goto err_out_exit_init;
 684         }
 685
 686         retval = driver_register(&w1_driver);
 687         if (retval) {
 688                 printk(KERN_ERR
 689                         "Failed to register master driver. err=%d.\n",
 690                         retval);
 691                 goto err_out_bus_unregister;
 692         }
 693
 694         control_thread = kernel_thread(&w1_control, NULL, 0);
 695         if (control_thread < 0) {
 696                 printk(KERN_ERR "Failed to create control thread. err=%d\n",
 697                         control_thread);
 698                 retval = control_thread;
 699                 goto err_out_driver_unregister;
 700         }
 701
 702         return 0;
 703
 704 err_out_driver_unregister:
 705         driver_unregister(&w1_driver);
 706
 707 err_out_bus_unregister:
 708         bus_unregister(&w1_bus_type);
 709
 710 err_out_exit_init:
 711         return retval;
 712 }
 713
 714 static void w1_fini(void)
 715 {
 716         struct w1_master *dev;
 717
 718         list_for_each_entry(dev, &w1_masters, w1_master_entry)
 719                 __w1_remove_master_device(dev);
 720
 721         control_needs_exit = 1;
 722         wait_for_completion(&w1_control_complete);
 723
 724         driver_unregister(&w1_driver);
 725         bus_unregister(&w1_bus_type);
 726 }
 727
 728 module_init(w1_init);
 729 module_exit(w1_fini);