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   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 #include <linux/kthread.h>
  34
  35 #include <asm/atomic.h>
  36
  37 #include "w1.h"
  38 #include "w1_io.h"
  39 #include "w1_log.h"
  40 #include "w1_int.h"
  41 #include "w1_family.h"
  42 #include "w1_netlink.h"
  43
  44 MODULE_LICENSE("GPL");
  45 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  46 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
  47
  48 static int w1_timeout = 10;
  49 static int w1_control_timeout = 1;
  50 int w1_max_slave_count = 10;
  51 int w1_max_slave_ttl = 10;
  52
  53 module_param_named(timeout, w1_timeout, int, 0);
  54 module_param_named(control_timeout, w1_control_timeout, int, 0);
  55 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
  56 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
  57
  58 DEFINE_SPINLOCK(w1_mlock);
  59 LIST_HEAD(w1_masters);
  60
  61 static struct task_struct *w1_control_thread;
  62
  63 static int w1_master_match(struct device *dev, struct device_driver *drv)
  64 {
  65         return 1;
  66 }
  67
  68 static int w1_master_probe(struct device *dev)
  69 {
  70         return -ENODEV;
  71 }
  72
  73 static void w1_master_release(struct device *dev)
  74 {
  75         struct w1_master *md = dev_to_w1_master(dev);
  76
  77         dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
  78
  79         dev_fini_netlink(md);
  80         memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
  81         kfree(md);
  82 }
  83
  84 static void w1_slave_release(struct device *dev)
  85 {
  86         struct w1_slave *sl = dev_to_w1_slave(dev);
  87
  88         dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name);
  89
  90         while (atomic_read(&sl->refcnt)) {
  91                 dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n",
  92                                 sl->name, atomic_read(&sl->refcnt));
  93                 if (msleep_interruptible(1000))
  94                         flush_signals(current);
  95         }
  96
  97         w1_family_put(sl->family);
  98         sl->master->slave_count--;
  99
 100         complete(&sl->released);
 101 }
 102
 103 static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
 104 {
 105         struct w1_slave *sl = dev_to_w1_slave(dev);
 106
 107         return sprintf(buf, "%s\n", sl->name);
 108 }
 109
 110 static ssize_t w1_slave_read_id(struct kobject *kobj, char *buf, loff_t off, size_t count)
 111 {
 112         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 113
 114         atomic_inc(&sl->refcnt);
 115         if (off > 8) {
 116                 count = 0;
 117         } else {
 118                 if (off + count > 8)
 119                         count = 8 - off;
 120
 121                 memcpy(buf, (u8 *)&sl->reg_num, count);
 122         }
 123         atomic_dec(&sl->refcnt);
 124
 125         return count;
 126 }
 127
 128 static struct device_attribute w1_slave_attr_name =
 129         __ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
 130
 131 static struct bin_attribute w1_slave_attr_bin_id = {
 132       .attr = {
 133               .name = "id",
 134               .mode = S_IRUGO,
 135               .owner = THIS_MODULE,
 136       },
 137       .size = 8,
 138       .read = w1_slave_read_id,
 139 };
 140
 141 /* Default family */
 142 static struct w1_family w1_default_family;
 143
 144 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size);
 145
 146 static struct bus_type w1_bus_type = {
 147         .name = "w1",
 148         .match = w1_master_match,
 149         .uevent = w1_uevent,
 150 };
 151
 152 struct device_driver w1_master_driver = {
 153         .name = "w1_master_driver",
 154         .bus = &w1_bus_type,
 155         .probe = w1_master_probe,
 156 };
 157
 158 struct device w1_master_device = {
 159         .parent = NULL,
 160         .bus = &w1_bus_type,
 161         .bus_id = "w1 bus master",
 162         .driver = &w1_master_driver,
 163         .release = &w1_master_release
 164 };
 165
 166 static struct device_driver w1_slave_driver = {
 167         .name = "w1_slave_driver",
 168         .bus = &w1_bus_type,
 169 };
 170
 171 #if 0
 172 struct device w1_slave_device = {
 173         .parent = NULL,
 174         .bus = &w1_bus_type,
 175         .bus_id = "w1 bus slave",
 176         .driver = &w1_slave_driver,
 177         .release = &w1_slave_release
 178 };
 179 #endif  /*  0  */
 180
 181 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
 182 {
 183         struct w1_master *md = dev_to_w1_master(dev);
 184         ssize_t count;
 185
 186         if (down_interruptible (&md->mutex))
 187                 return -EBUSY;
 188
 189         count = sprintf(buf, "%s\n", md->name);
 190
 191         up(&md->mutex);
 192
 193         return count;
 194 }
 195
 196 static ssize_t w1_master_attribute_store_search(struct device * dev,
 197                                                 struct device_attribute *attr,
 198                                                 const char * buf, size_t count)
 199 {
 200         struct w1_master *md = dev_to_w1_master(dev);
 201
 202         if (down_interruptible (&md->mutex))
 203                 return -EBUSY;
 204
 205         md->search_count = simple_strtol(buf, NULL, 0);
 206
 207         up(&md->mutex);
 208
 209         return count;
 210 }
 211
 212 static ssize_t w1_master_attribute_show_search(struct device *dev,
 213                                                struct device_attribute *attr,
 214                                                char *buf)
 215 {
 216         struct w1_master *md = dev_to_w1_master(dev);
 217         ssize_t count;
 218
 219         if (down_interruptible (&md->mutex))
 220                 return -EBUSY;
 221
 222         count = sprintf(buf, "%d\n", md->search_count);
 223
 224         up(&md->mutex);
 225
 226         return count;
 227 }
 228
 229 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
 230 {
 231         struct w1_master *md = dev_to_w1_master(dev);
 232         ssize_t count;
 233
 234         if (down_interruptible(&md->mutex))
 235                 return -EBUSY;
 236
 237         count = sprintf(buf, "0x%p\n", md->bus_master);
 238
 239         up(&md->mutex);
 240         return count;
 241 }
 242
 243 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
 244 {
 245         ssize_t count;
 246         count = sprintf(buf, "%d\n", w1_timeout);
 247         return count;
 248 }
 249
 250 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 251 {
 252         struct w1_master *md = dev_to_w1_master(dev);
 253         ssize_t count;
 254
 255         if (down_interruptible(&md->mutex))
 256                 return -EBUSY;
 257
 258         count = sprintf(buf, "%d\n", md->max_slave_count);
 259
 260         up(&md->mutex);
 261         return count;
 262 }
 263
 264 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
 265 {
 266         struct w1_master *md = dev_to_w1_master(dev);
 267         ssize_t count;
 268
 269         if (down_interruptible(&md->mutex))
 270                 return -EBUSY;
 271
 272         count = sprintf(buf, "%lu\n", md->attempts);
 273
 274         up(&md->mutex);
 275         return count;
 276 }
 277
 278 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 279 {
 280         struct w1_master *md = dev_to_w1_master(dev);
 281         ssize_t count;
 282
 283         if (down_interruptible(&md->mutex))
 284                 return -EBUSY;
 285
 286         count = sprintf(buf, "%d\n", md->slave_count);
 287
 288         up(&md->mutex);
 289         return count;
 290 }
 291
 292 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
 293 {
 294         struct w1_master *md = dev_to_w1_master(dev);
 295         int c = PAGE_SIZE;
 296
 297         if (down_interruptible(&md->mutex))
 298                 return -EBUSY;
 299
 300         if (md->slave_count == 0)
 301                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
 302         else {
 303                 struct list_head *ent, *n;
 304                 struct w1_slave *sl;
 305
 306                 list_for_each_safe(ent, n, &md->slist) {
 307                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 308
 309                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
 310                 }
 311         }
 312
 313         up(&md->mutex);
 314
 315         return PAGE_SIZE - c;
 316 }
 317
 318 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
 319         struct device_attribute w1_master_attribute_##_name =   \
 320                 __ATTR(w1_master_##_name, _mode,                \
 321                        w1_master_attribute_show_##_name, NULL)
 322
 323 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
 324         struct device_attribute w1_master_attribute_##_name =   \
 325                 __ATTR(w1_master_##_name, _mode,                \
 326                        w1_master_attribute_show_##_name,        \
 327                        w1_master_attribute_store_##_name)
 328
 329 static W1_MASTER_ATTR_RO(name, S_IRUGO);
 330 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
 331 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
 332 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
 333 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
 334 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
 335 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
 336 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
 337
 338 static struct attribute *w1_master_default_attrs[] = {
 339         &w1_master_attribute_name.attr,
 340         &w1_master_attribute_slaves.attr,
 341         &w1_master_attribute_slave_count.attr,
 342         &w1_master_attribute_max_slave_count.attr,
 343         &w1_master_attribute_attempts.attr,
 344         &w1_master_attribute_timeout.attr,
 345         &w1_master_attribute_pointer.attr,
 346         &w1_master_attribute_search.attr,
 347         NULL
 348 };
 349
 350 static struct attribute_group w1_master_defattr_group = {
 351         .attrs = w1_master_default_attrs,
 352 };
 353
 354 int w1_create_master_attributes(struct w1_master *master)
 355 {
 356         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
 357 }
 358
 359 static void w1_destroy_master_attributes(struct w1_master *master)
 360 {
 361         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
 362 }
 363
 364 #ifdef CONFIG_HOTPLUG
 365 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
 366 {
 367         struct w1_master *md = NULL;
 368         struct w1_slave *sl = NULL;
 369         char *event_owner, *name;
 370         int err, cur_index=0, cur_len=0;
 371
 372         if (dev->driver == &w1_master_driver) {
 373                 md = container_of(dev, struct w1_master, dev);
 374                 event_owner = "master";
 375                 name = md->name;
 376         } else if (dev->driver == &w1_slave_driver) {
 377                 sl = container_of(dev, struct w1_slave, dev);
 378                 event_owner = "slave";
 379                 name = sl->name;
 380         } else {
 381                 dev_dbg(dev, "Unknown event.\n");
 382                 return -EINVAL;
 383         }
 384
 385         dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n", event_owner, name, dev->bus_id);
 386
 387         if (dev->driver != &w1_slave_driver || !sl)
 388                 return 0;
 389
 390         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
 391                         &cur_len, "W1_FID=%02X", sl->reg_num.family);
 392         if (err)
 393                 return err;
 394
 395         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
 396                         &cur_len, "W1_SLAVE_ID=%024LX",
 397                         (unsigned long long)sl->reg_num.id);
 398         if (err)
 399                 return err;
 400
 401         return 0;
 402 };
 403 #else
 404 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
 405 {
 406         return 0;
 407 }
 408 #endif
 409
 410 static int __w1_attach_slave_device(struct w1_slave *sl)
 411 {
 412         int err;
 413
 414         sl->dev.parent = &sl->master->dev;
 415         sl->dev.driver = &w1_slave_driver;
 416         sl->dev.bus = &w1_bus_type;
 417         sl->dev.release = &w1_slave_release;
 418
 419         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
 420                  "%02x-%012llx",
 421                  (unsigned int) sl->reg_num.family,
 422                  (unsigned long long) sl->reg_num.id);
 423         snprintf(&sl->name[0], sizeof(sl->name),
 424                  "%02x-%012llx",
 425                  (unsigned int) sl->reg_num.family,
 426                  (unsigned long long) sl->reg_num.id);
 427
 428         dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__, &sl->dev.bus_id[0]);
 429
 430         err = device_register(&sl->dev);
 431         if (err < 0) {
 432                 dev_err(&sl->dev,
 433                         "Device registration [%s] failed. err=%d\n",
 434                         sl->dev.bus_id, err);
 435                 return err;
 436         }
 437
 438         /* Create "name" entry */
 439         err = device_create_file(&sl->dev, &w1_slave_attr_name);
 440         if (err < 0) {
 441                 dev_err(&sl->dev,
 442                         "sysfs file creation for [%s] failed. err=%d\n",
 443                         sl->dev.bus_id, err);
 444                 goto out_unreg;
 445         }
 446
 447         /* Create "id" entry */
 448         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 449         if (err < 0) {
 450                 dev_err(&sl->dev,
 451                         "sysfs file creation for [%s] failed. err=%d\n",
 452                         sl->dev.bus_id, err);
 453                 goto out_rem1;
 454         }
 455
 456         /* if the family driver needs to initialize something... */
 457         if (sl->family->fops && sl->family->fops->add_slave &&
 458             ((err = sl->family->fops->add_slave(sl)) < 0)) {
 459                 dev_err(&sl->dev,
 460                         "sysfs file creation for [%s] failed. err=%d\n",
 461                         sl->dev.bus_id, err);
 462                 goto out_rem2;
 463         }
 464
 465         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
 466
 467         return 0;
 468
 469 out_rem2:
 470         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 471 out_rem1:
 472         device_remove_file(&sl->dev, &w1_slave_attr_name);
 473 out_unreg:
 474         device_unregister(&sl->dev);
 475         return err;
 476 }
 477
 478 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
 479 {
 480         struct w1_slave *sl;
 481         struct w1_family *f;
 482         int err;
 483         struct w1_netlink_msg msg;
 484
 485         sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
 486         if (!sl) {
 487                 dev_err(&dev->dev,
 488                          "%s: failed to allocate new slave device.\n",
 489                          __func__);
 490                 return -ENOMEM;
 491         }
 492
 493         memset(sl, 0, sizeof(*sl));
 494
 495         sl->owner = THIS_MODULE;
 496         sl->master = dev;
 497         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 498
 499         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
 500         atomic_set(&sl->refcnt, 0);
 501         init_completion(&sl->released);
 502
 503         spin_lock(&w1_flock);
 504         f = w1_family_registered(rn->family);
 505         if (!f) {
 506                 f= &w1_default_family;
 507                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
 508                           rn->family, rn->family,
 509                           (unsigned long long)rn->id, rn->crc);
 510         }
 511         __w1_family_get(f);
 512         spin_unlock(&w1_flock);
 513
 514         sl->family = f;
 515
 516
 517         err = __w1_attach_slave_device(sl);
 518         if (err < 0) {
 519                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
 520                          sl->name);
 521                 w1_family_put(sl->family);
 522                 kfree(sl);
 523                 return err;
 524         }
 525
 526         sl->ttl = dev->slave_ttl;
 527         dev->slave_count++;
 528
 529         memcpy(&msg.id.id, rn, sizeof(msg.id.id));
 530         msg.type = W1_SLAVE_ADD;
 531         w1_netlink_send(dev, &msg);
 532
 533         return 0;
 534 }
 535
 536 static void w1_slave_detach(struct w1_slave *sl)
 537 {
 538         struct w1_netlink_msg msg;
 539
 540         dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
 541
 542         list_del(&sl->w1_slave_entry);
 543
 544         if (sl->family->fops && sl->family->fops->remove_slave)
 545                 sl->family->fops->remove_slave(sl);
 546
 547         memcpy(&msg.id.id, &sl->reg_num, sizeof(msg.id.id));
 548         msg.type = W1_SLAVE_REMOVE;
 549         w1_netlink_send(sl->master, &msg);
 550
 551         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 552         device_remove_file(&sl->dev, &w1_slave_attr_name);
 553         device_unregister(&sl->dev);
 554
 555         wait_for_completion(&sl->released);
 556         kfree(sl);
 557 }
 558
 559 static struct w1_master *w1_search_master(void *data)
 560 {
 561         struct w1_master *dev;
 562         int found = 0;
 563
 564         spin_lock_bh(&w1_mlock);
 565         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 566                 if (dev->bus_master->data == data) {
 567                         found = 1;
 568                         atomic_inc(&dev->refcnt);
 569                         break;
 570                 }
 571         }
 572         spin_unlock_bh(&w1_mlock);
 573
 574         return (found)?dev:NULL;
 575 }
 576
 577 void w1_reconnect_slaves(struct w1_family *f)
 578 {
 579         struct w1_master *dev;
 580
 581         spin_lock_bh(&w1_mlock);
 582         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 583                 dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
 584                                 dev->name, f->fid);
 585                 set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
 586         }
 587         spin_unlock_bh(&w1_mlock);
 588 }
 589
 590 static void w1_slave_found(void *data, u64 rn)
 591 {
 592         int slave_count;
 593         struct w1_slave *sl;
 594         struct list_head *ent;
 595         struct w1_reg_num *tmp;
 596         int family_found = 0;
 597         struct w1_master *dev;
 598         u64 rn_le = cpu_to_le64(rn);
 599
 600         dev = w1_search_master(data);
 601         if (!dev) {
 602                 printk(KERN_ERR "Failed to find w1 master device for data %p, "
 603                        "it is impossible.\n", data);
 604                 return;
 605         }
 606
 607         tmp = (struct w1_reg_num *) &rn;
 608
 609         slave_count = 0;
 610         list_for_each(ent, &dev->slist) {
 611
 612                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 613
 614                 if (sl->reg_num.family == tmp->family &&
 615                     sl->reg_num.id == tmp->id &&
 616                     sl->reg_num.crc == tmp->crc) {
 617                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 618                         break;
 619                 } else if (sl->reg_num.family == tmp->family) {
 620                         family_found = 1;
 621                         break;
 622                 }
 623
 624                 slave_count++;
 625         }
 626
 627         if (slave_count == dev->slave_count &&
 628                 rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
 629                 w1_attach_slave_device(dev, tmp);
 630         }
 631
 632         atomic_dec(&dev->refcnt);
 633 }
 634
 635 /**
 636  * Performs a ROM Search & registers any devices found.
 637  * The 1-wire search is a simple binary tree search.
 638  * For each bit of the address, we read two bits and write one bit.
 639  * The bit written will put to sleep all devies that don't match that bit.
 640  * When the two reads differ, the direction choice is obvious.
 641  * When both bits are 0, we must choose a path to take.
 642  * When we can scan all 64 bits without having to choose a path, we are done.
 643  *
 644  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
 645  *
 646  * @dev        The master device to search
 647  * @cb         Function to call when a device is found
 648  */
 649 void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
 650 {
 651         u64 last_rn, rn, tmp64;
 652         int i, slave_count = 0;
 653         int last_zero, last_device;
 654         int search_bit, desc_bit;
 655         u8  triplet_ret = 0;
 656
 657         search_bit = 0;
 658         rn = last_rn = 0;
 659         last_device = 0;
 660         last_zero = -1;
 661
 662         desc_bit = 64;
 663
 664         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
 665                 last_rn = rn;
 666                 rn = 0;
 667
 668                 /*
 669                  * Reset bus and all 1-wire device state machines
 670                  * so they can respond to our requests.
 671                  *
 672                  * Return 0 - device(s) present, 1 - no devices present.
 673                  */
 674                 if (w1_reset_bus(dev)) {
 675                         dev_dbg(&dev->dev, "No devices present on the wire.\n");
 676                         break;
 677                 }
 678
 679                 /* Start the search */
 680                 w1_write_8(dev, W1_SEARCH);
 681                 for (i = 0; i < 64; ++i) {
 682                         /* Determine the direction/search bit */
 683                         if (i == desc_bit)
 684                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
 685                         else if (i > desc_bit)
 686                                 search_bit = 0;   /* take the 0 path on the next branch */
 687                         else
 688                                 search_bit = ((last_rn >> i) & 0x1);
 689
 690                         /** Read two bits and write one bit */
 691                         triplet_ret = w1_triplet(dev, search_bit);
 692
 693                         /* quit if no device responded */
 694                         if ( (triplet_ret & 0x03) == 0x03 )
 695                                 break;
 696
 697                         /* If both directions were valid, and we took the 0 path... */
 698                         if (triplet_ret == 0)
 699                                 last_zero = i;
 700
 701                         /* extract the direction taken & update the device number */
 702                         tmp64 = (triplet_ret >> 2);
 703                         rn |= (tmp64 << i);
 704                 }
 705
 706                 if ( (triplet_ret & 0x03) != 0x03 ) {
 707                         if ( (desc_bit == last_zero) || (last_zero < 0))
 708                                 last_device = 1;
 709                         desc_bit = last_zero;
 710                         cb(dev->bus_master->data, rn);
 711                 }
 712         }
 713 }
 714
 715 static int w1_control(void *data)
 716 {
 717         struct w1_slave *sl, *sln;
 718         struct w1_master *dev, *n;
 719         int have_to_wait = 0;
 720
 721         while (!kthread_should_stop() || have_to_wait) {
 722                 have_to_wait = 0;
 723
 724                 try_to_freeze();
 725                 msleep_interruptible(w1_control_timeout * 1000);
 726
 727                 list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
 728                         if (!kthread_should_stop() && !dev->flags)
 729                                 continue;
 730                         /*
 731                          * Little race: we can create thread but not set the flag.
 732                          * Get a chance for external process to set flag up.
 733                          */
 734                         if (!dev->initialized) {
 735                                 have_to_wait = 1;
 736                                 continue;
 737                         }
 738
 739                         if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
 740                                 set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
 741
 742                                 spin_lock(&w1_mlock);
 743                                 list_del(&dev->w1_master_entry);
 744                                 spin_unlock(&w1_mlock);
 745
 746                                 down(&dev->mutex);
 747                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 748                                         w1_slave_detach(sl);
 749                                 }
 750                                 w1_destroy_master_attributes(dev);
 751                                 up(&dev->mutex);
 752                                 atomic_dec(&dev->refcnt);
 753                                 continue;
 754                         }
 755
 756                         if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
 757                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
 758                                 down(&dev->mutex);
 759                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 760                                         if (sl->family->fid == W1_FAMILY_DEFAULT) {
 761                                                 struct w1_reg_num rn;
 762
 763                                                 memcpy(&rn, &sl->reg_num, sizeof(rn));
 764                                                 w1_slave_detach(sl);
 765
 766                                                 w1_attach_slave_device(dev, &rn);
 767                                         }
 768                                 }
 769                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
 770                                 clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
 771                                 up(&dev->mutex);
 772                         }
 773                 }
 774         }
 775
 776         return 0;
 777 }
 778
 779 int w1_process(void *data)
 780 {
 781         struct w1_master *dev = (struct w1_master *) data;
 782         struct w1_slave *sl, *sln;
 783
 784         while (!kthread_should_stop() && !test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
 785                 try_to_freeze();
 786                 msleep_interruptible(w1_timeout * 1000);
 787
 788                 if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
 789                         break;
 790
 791                 if (!dev->initialized)
 792                         continue;
 793
 794                 if (dev->search_count == 0)
 795                         continue;
 796
 797                 if (down_interruptible(&dev->mutex))
 798                         continue;
 799
 800                 list_for_each_entry(sl, &dev->slist, w1_slave_entry)
 801                         clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 802
 803                 w1_search_devices(dev, w1_slave_found);
 804
 805                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 806                         if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
 807                                 w1_slave_detach(sl);
 808
 809                                 dev->slave_count--;
 810                         } else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
 811                                 sl->ttl = dev->slave_ttl;
 812                 }
 813
 814                 if (dev->search_count > 0)
 815                         dev->search_count--;
 816
 817                 up(&dev->mutex);
 818         }
 819
 820         atomic_dec(&dev->refcnt);
 821
 822         return 0;
 823 }
 824
 825 static int w1_init(void)
 826 {
 827         int retval;
 828
 829         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
 830
 831         retval = bus_register(&w1_bus_type);
 832         if (retval) {
 833                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
 834                 goto err_out_exit_init;
 835         }
 836
 837         retval = driver_register(&w1_master_driver);
 838         if (retval) {
 839                 printk(KERN_ERR
 840                         "Failed to register master driver. err=%d.\n",
 841                         retval);
 842                 goto err_out_bus_unregister;
 843         }
 844
 845         retval = driver_register(&w1_slave_driver);
 846         if (retval) {
 847                 printk(KERN_ERR
 848                         "Failed to register master driver. err=%d.\n",
 849                         retval);
 850                 goto err_out_master_unregister;
 851         }
 852
 853         w1_control_thread = kthread_run(w1_control, NULL, "w1_control");
 854         if (IS_ERR(w1_control_thread)) {
 855                 retval = PTR_ERR(w1_control_thread);
 856                 printk(KERN_ERR "Failed to create control thread. err=%d\n",
 857                         retval);
 858                 goto err_out_slave_unregister;
 859         }
 860
 861         return 0;
 862
 863 err_out_slave_unregister:
 864         driver_unregister(&w1_slave_driver);
 865
 866 err_out_master_unregister:
 867         driver_unregister(&w1_master_driver);
 868
 869 err_out_bus_unregister:
 870         bus_unregister(&w1_bus_type);
 871
 872 err_out_exit_init:
 873         return retval;
 874 }
 875
 876 static void w1_fini(void)
 877 {
 878         struct w1_master *dev;
 879
 880         list_for_each_entry(dev, &w1_masters, w1_master_entry)
 881                 __w1_remove_master_device(dev);
 882
 883         kthread_stop(w1_control_thread);
 884
 885         driver_unregister(&w1_slave_driver);
 886         driver_unregister(&w1_master_driver);
 887         bus_unregister(&w1_bus_type);
 888 }
 889
 890 module_init(w1_init);
 891 module_exit(w1_fini);