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 static int w1_control_timeout = 1;
  49 int w1_max_slave_count = 10;
  50 int w1_max_slave_ttl = 10;
  51
  52 module_param_named(timeout, w1_timeout, int, 0);
  53 module_param_named(control_timeout, w1_control_timeout, int, 0);
  54 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
  55 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
  56
  57 DEFINE_SPINLOCK(w1_mlock);
  58 LIST_HEAD(w1_masters);
  59
  60 static pid_t control_thread;
  61 static int control_needs_exit;
  62 static DECLARE_COMPLETION(w1_control_complete);
  63
  64 static int w1_master_match(struct device *dev, struct device_driver *drv)
  65 {
  66         return 1;
  67 }
  68
  69 static int w1_master_probe(struct device *dev)
  70 {
  71         return -ENODEV;
  72 }
  73
  74 static void w1_master_release(struct device *dev)
  75 {
  76         struct w1_master *md = dev_to_w1_master(dev);
  77
  78         dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
  79
  80         dev_fini_netlink(md);
  81         memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
  82         kfree(md);
  83 }
  84
  85 static void w1_slave_release(struct device *dev)
  86 {
  87         struct w1_slave *sl = dev_to_w1_slave(dev);
  88
  89         dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name);
  90
  91         while (atomic_read(&sl->refcnt)) {
  92                 dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n",
  93                                 sl->name, atomic_read(&sl->refcnt));
  94                 if (msleep_interruptible(1000))
  95                         flush_signals(current);
  96         }
  97
  98         w1_family_put(sl->family);
  99         sl->master->slave_count--;
 100
 101         complete(&sl->released);
 102 }
 103
 104 static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
 105 {
 106         struct w1_slave *sl = dev_to_w1_slave(dev);
 107
 108         return sprintf(buf, "%s\n", sl->name);
 109 }
 110
 111 static ssize_t w1_slave_read_id(struct kobject *kobj, char *buf, loff_t off, size_t count)
 112 {
 113         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 114
 115         atomic_inc(&sl->refcnt);
 116         if (off > 8) {
 117                 count = 0;
 118         } else {
 119                 if (off + count > 8)
 120                         count = 8 - off;
 121
 122                 memcpy(buf, (u8 *)&sl->reg_num, count);
 123         }
 124         atomic_dec(&sl->refcnt);
 125
 126         return count;
 127 }
 128
 129 static struct device_attribute w1_slave_attr_name =
 130         __ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
 131
 132 static struct bin_attribute w1_slave_attr_bin_id = {
 133       .attr = {
 134               .name = "id",
 135               .mode = S_IRUGO,
 136               .owner = THIS_MODULE,
 137       },
 138       .size = 8,
 139       .read = w1_slave_read_id,
 140 };
 141
 142 /* Default family */
 143 static struct w1_family w1_default_family;
 144
 145 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size);
 146
 147 static struct bus_type w1_bus_type = {
 148         .name = "w1",
 149         .match = w1_master_match,
 150         .uevent = w1_uevent,
 151 };
 152
 153 struct device_driver w1_master_driver = {
 154         .name = "w1_master_driver",
 155         .bus = &w1_bus_type,
 156         .probe = w1_master_probe,
 157 };
 158
 159 struct device w1_master_device = {
 160         .parent = NULL,
 161         .bus = &w1_bus_type,
 162         .bus_id = "w1 bus master",
 163         .driver = &w1_master_driver,
 164         .release = &w1_master_release
 165 };
 166
 167 static struct device_driver w1_slave_driver = {
 168         .name = "w1_slave_driver",
 169         .bus = &w1_bus_type,
 170 };
 171
 172 #if 0
 173 struct device w1_slave_device = {
 174         .parent = NULL,
 175         .bus = &w1_bus_type,
 176         .bus_id = "w1 bus slave",
 177         .driver = &w1_slave_driver,
 178         .release = &w1_slave_release
 179 };
 180 #endif  /*  0  */
 181
 182 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
 183 {
 184         struct w1_master *md = dev_to_w1_master(dev);
 185         ssize_t count;
 186
 187         if (down_interruptible (&md->mutex))
 188                 return -EBUSY;
 189
 190         count = sprintf(buf, "%s\n", md->name);
 191
 192         up(&md->mutex);
 193
 194         return count;
 195 }
 196
 197 static ssize_t w1_master_attribute_store_search(struct device * dev,
 198                                                 struct device_attribute *attr,
 199                                                 const char * buf, size_t count)
 200 {
 201         struct w1_master *md = dev_to_w1_master(dev);
 202
 203         if (down_interruptible (&md->mutex))
 204                 return -EBUSY;
 205
 206         md->search_count = simple_strtol(buf, NULL, 0);
 207
 208         up(&md->mutex);
 209
 210         return count;
 211 }
 212
 213 static ssize_t w1_master_attribute_show_search(struct device *dev,
 214                                                struct device_attribute *attr,
 215                                                char *buf)
 216 {
 217         struct w1_master *md = dev_to_w1_master(dev);
 218         ssize_t count;
 219
 220         if (down_interruptible (&md->mutex))
 221                 return -EBUSY;
 222
 223         count = sprintf(buf, "%d\n", md->search_count);
 224
 225         up(&md->mutex);
 226
 227         return count;
 228 }
 229
 230 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
 231 {
 232         struct w1_master *md = dev_to_w1_master(dev);
 233         ssize_t count;
 234
 235         if (down_interruptible(&md->mutex))
 236                 return -EBUSY;
 237
 238         count = sprintf(buf, "0x%p\n", md->bus_master);
 239
 240         up(&md->mutex);
 241         return count;
 242 }
 243
 244 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
 245 {
 246         ssize_t count;
 247         count = sprintf(buf, "%d\n", w1_timeout);
 248         return count;
 249 }
 250
 251 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 252 {
 253         struct w1_master *md = dev_to_w1_master(dev);
 254         ssize_t count;
 255
 256         if (down_interruptible(&md->mutex))
 257                 return -EBUSY;
 258
 259         count = sprintf(buf, "%d\n", md->max_slave_count);
 260
 261         up(&md->mutex);
 262         return count;
 263 }
 264
 265 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
 266 {
 267         struct w1_master *md = dev_to_w1_master(dev);
 268         ssize_t count;
 269
 270         if (down_interruptible(&md->mutex))
 271                 return -EBUSY;
 272
 273         count = sprintf(buf, "%lu\n", md->attempts);
 274
 275         up(&md->mutex);
 276         return count;
 277 }
 278
 279 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 280 {
 281         struct w1_master *md = dev_to_w1_master(dev);
 282         ssize_t count;
 283
 284         if (down_interruptible(&md->mutex))
 285                 return -EBUSY;
 286
 287         count = sprintf(buf, "%d\n", md->slave_count);
 288
 289         up(&md->mutex);
 290         return count;
 291 }
 292
 293 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
 294 {
 295         struct w1_master *md = dev_to_w1_master(dev);
 296         int c = PAGE_SIZE;
 297
 298         if (down_interruptible(&md->mutex))
 299                 return -EBUSY;
 300
 301         if (md->slave_count == 0)
 302                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
 303         else {
 304                 struct list_head *ent, *n;
 305                 struct w1_slave *sl;
 306
 307                 list_for_each_safe(ent, n, &md->slist) {
 308                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 309
 310                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
 311                 }
 312         }
 313
 314         up(&md->mutex);
 315
 316         return PAGE_SIZE - c;
 317 }
 318
 319 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
 320         struct device_attribute w1_master_attribute_##_name =   \
 321                 __ATTR(w1_master_##_name, _mode,                \
 322                        w1_master_attribute_show_##_name, NULL)
 323
 324 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
 325         struct device_attribute w1_master_attribute_##_name =   \
 326                 __ATTR(w1_master_##_name, _mode,                \
 327                        w1_master_attribute_show_##_name,        \
 328                        w1_master_attribute_store_##_name)
 329
 330 static W1_MASTER_ATTR_RO(name, S_IRUGO);
 331 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
 332 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
 333 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
 334 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
 335 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
 336 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
 337 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
 338
 339 static struct attribute *w1_master_default_attrs[] = {
 340         &w1_master_attribute_name.attr,
 341         &w1_master_attribute_slaves.attr,
 342         &w1_master_attribute_slave_count.attr,
 343         &w1_master_attribute_max_slave_count.attr,
 344         &w1_master_attribute_attempts.attr,
 345         &w1_master_attribute_timeout.attr,
 346         &w1_master_attribute_pointer.attr,
 347         &w1_master_attribute_search.attr,
 348         NULL
 349 };
 350
 351 static struct attribute_group w1_master_defattr_group = {
 352         .attrs = w1_master_default_attrs,
 353 };
 354
 355 int w1_create_master_attributes(struct w1_master *master)
 356 {
 357         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
 358 }
 359
 360 static void w1_destroy_master_attributes(struct w1_master *master)
 361 {
 362         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
 363 }
 364
 365 #ifdef CONFIG_HOTPLUG
 366 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
 367 {
 368         struct w1_master *md = NULL;
 369         struct w1_slave *sl = NULL;
 370         char *event_owner, *name;
 371         int err, cur_index=0, cur_len=0;
 372
 373         if (dev->driver == &w1_master_driver) {
 374                 md = container_of(dev, struct w1_master, dev);
 375                 event_owner = "master";
 376                 name = md->name;
 377         } else if (dev->driver == &w1_slave_driver) {
 378                 sl = container_of(dev, struct w1_slave, dev);
 379                 event_owner = "slave";
 380                 name = sl->name;
 381         } else {
 382                 dev_dbg(dev, "Unknown event.\n");
 383                 return -EINVAL;
 384         }
 385
 386         dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n", event_owner, name, dev->bus_id);
 387
 388         if (dev->driver != &w1_slave_driver || !sl)
 389                 return 0;
 390
 391         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
 392                         &cur_len, "W1_FID=%02X", sl->reg_num.family);
 393         if (err)
 394                 return err;
 395
 396         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
 397                         &cur_len, "W1_SLAVE_ID=%024LX",
 398                         (unsigned long long)sl->reg_num.id);
 399         if (err)
 400                 return err;
 401
 402         return 0;
 403 };
 404 #else
 405 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
 406 {
 407         return 0;
 408 }
 409 #endif
 410
 411 static int __w1_attach_slave_device(struct w1_slave *sl)
 412 {
 413         int err;
 414
 415         sl->dev.parent = &sl->master->dev;
 416         sl->dev.driver = &w1_slave_driver;
 417         sl->dev.bus = &w1_bus_type;
 418         sl->dev.release = &w1_slave_release;
 419
 420         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
 421                  "%02x-%012llx",
 422                  (unsigned int) sl->reg_num.family,
 423                  (unsigned long long) sl->reg_num.id);
 424         snprintf(&sl->name[0], sizeof(sl->name),
 425                  "%02x-%012llx",
 426                  (unsigned int) sl->reg_num.family,
 427                  (unsigned long long) sl->reg_num.id);
 428
 429         dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__, &sl->dev.bus_id[0]);
 430
 431         err = device_register(&sl->dev);
 432         if (err < 0) {
 433                 dev_err(&sl->dev,
 434                         "Device registration [%s] failed. err=%d\n",
 435                         sl->dev.bus_id, err);
 436                 return err;
 437         }
 438
 439         /* Create "name" entry */
 440         err = device_create_file(&sl->dev, &w1_slave_attr_name);
 441         if (err < 0) {
 442                 dev_err(&sl->dev,
 443                         "sysfs file creation for [%s] failed. err=%d\n",
 444                         sl->dev.bus_id, err);
 445                 goto out_unreg;
 446         }
 447
 448         /* Create "id" entry */
 449         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 450         if (err < 0) {
 451                 dev_err(&sl->dev,
 452                         "sysfs file creation for [%s] failed. err=%d\n",
 453                         sl->dev.bus_id, err);
 454                 goto out_rem1;
 455         }
 456
 457         /* if the family driver needs to initialize something... */
 458         if (sl->family->fops && sl->family->fops->add_slave &&
 459             ((err = sl->family->fops->add_slave(sl)) < 0)) {
 460                 dev_err(&sl->dev,
 461                         "sysfs file creation for [%s] failed. err=%d\n",
 462                         sl->dev.bus_id, err);
 463                 goto out_rem2;
 464         }
 465
 466         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
 467
 468         return 0;
 469
 470 out_rem2:
 471         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 472 out_rem1:
 473         device_remove_file(&sl->dev, &w1_slave_attr_name);
 474 out_unreg:
 475         device_unregister(&sl->dev);
 476         return err;
 477 }
 478
 479 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
 480 {
 481         struct w1_slave *sl;
 482         struct w1_family *f;
 483         int err;
 484         struct w1_netlink_msg msg;
 485
 486         sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
 487         if (!sl) {
 488                 dev_err(&dev->dev,
 489                          "%s: failed to allocate new slave device.\n",
 490                          __func__);
 491                 return -ENOMEM;
 492         }
 493
 494         memset(sl, 0, sizeof(*sl));
 495
 496         sl->owner = THIS_MODULE;
 497         sl->master = dev;
 498         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 499
 500         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
 501         atomic_set(&sl->refcnt, 0);
 502         init_completion(&sl->released);
 503
 504         spin_lock(&w1_flock);
 505         f = w1_family_registered(rn->family);
 506         if (!f) {
 507                 f= &w1_default_family;
 508                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
 509                           rn->family, rn->family,
 510                           (unsigned long long)rn->id, rn->crc);
 511         }
 512         __w1_family_get(f);
 513         spin_unlock(&w1_flock);
 514
 515         sl->family = f;
 516
 517
 518         err = __w1_attach_slave_device(sl);
 519         if (err < 0) {
 520                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
 521                          sl->name);
 522                 w1_family_put(sl->family);
 523                 kfree(sl);
 524                 return err;
 525         }
 526
 527         sl->ttl = dev->slave_ttl;
 528         dev->slave_count++;
 529
 530         memcpy(&msg.id.id, rn, sizeof(msg.id.id));
 531         msg.type = W1_SLAVE_ADD;
 532         w1_netlink_send(dev, &msg);
 533
 534         return 0;
 535 }
 536
 537 static void w1_slave_detach(struct w1_slave *sl)
 538 {
 539         struct w1_netlink_msg msg;
 540
 541         dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
 542
 543         list_del(&sl->w1_slave_entry);
 544
 545         if (sl->family->fops && sl->family->fops->remove_slave)
 546                 sl->family->fops->remove_slave(sl);
 547
 548         memcpy(&msg.id.id, &sl->reg_num, sizeof(msg.id.id));
 549         msg.type = W1_SLAVE_REMOVE;
 550         w1_netlink_send(sl->master, &msg);
 551
 552         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 553         device_remove_file(&sl->dev, &w1_slave_attr_name);
 554         device_unregister(&sl->dev);
 555
 556         wait_for_completion(&sl->released);
 557         kfree(sl);
 558 }
 559
 560 static struct w1_master *w1_search_master(void *data)
 561 {
 562         struct w1_master *dev;
 563         int found = 0;
 564
 565         spin_lock_bh(&w1_mlock);
 566         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 567                 if (dev->bus_master->data == data) {
 568                         found = 1;
 569                         atomic_inc(&dev->refcnt);
 570                         break;
 571                 }
 572         }
 573         spin_unlock_bh(&w1_mlock);
 574
 575         return (found)?dev:NULL;
 576 }
 577
 578 void w1_reconnect_slaves(struct w1_family *f)
 579 {
 580         struct w1_master *dev;
 581
 582         spin_lock_bh(&w1_mlock);
 583         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 584                 dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
 585                                 dev->name, f->fid);
 586                 set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
 587         }
 588         spin_unlock_bh(&w1_mlock);
 589 }
 590
 591 static void w1_slave_found(void *data, u64 rn)
 592 {
 593         int slave_count;
 594         struct w1_slave *sl;
 595         struct list_head *ent;
 596         struct w1_reg_num *tmp;
 597         int family_found = 0;
 598         struct w1_master *dev;
 599         u64 rn_le = cpu_to_le64(rn);
 600
 601         dev = w1_search_master(data);
 602         if (!dev) {
 603                 printk(KERN_ERR "Failed to find w1 master device for data %p, "
 604                        "it is impossible.\n", data);
 605                 return;
 606         }
 607
 608         tmp = (struct w1_reg_num *) &rn;
 609
 610         slave_count = 0;
 611         list_for_each(ent, &dev->slist) {
 612
 613                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 614
 615                 if (sl->reg_num.family == tmp->family &&
 616                     sl->reg_num.id == tmp->id &&
 617                     sl->reg_num.crc == tmp->crc) {
 618                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 619                         break;
 620                 } else if (sl->reg_num.family == tmp->family) {
 621                         family_found = 1;
 622                         break;
 623                 }
 624
 625                 slave_count++;
 626         }
 627
 628         if (slave_count == dev->slave_count &&
 629                 rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
 630                 w1_attach_slave_device(dev, tmp);
 631         }
 632
 633         atomic_dec(&dev->refcnt);
 634 }
 635
 636 /**
 637  * Performs a ROM Search & registers any devices found.
 638  * The 1-wire search is a simple binary tree search.
 639  * For each bit of the address, we read two bits and write one bit.
 640  * The bit written will put to sleep all devies that don't match that bit.
 641  * When the two reads differ, the direction choice is obvious.
 642  * When both bits are 0, we must choose a path to take.
 643  * When we can scan all 64 bits without having to choose a path, we are done.
 644  *
 645  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
 646  *
 647  * @dev        The master device to search
 648  * @cb         Function to call when a device is found
 649  */
 650 void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
 651 {
 652         u64 last_rn, rn, tmp64;
 653         int i, slave_count = 0;
 654         int last_zero, last_device;
 655         int search_bit, desc_bit;
 656         u8  triplet_ret = 0;
 657
 658         search_bit = 0;
 659         rn = last_rn = 0;
 660         last_device = 0;
 661         last_zero = -1;
 662
 663         desc_bit = 64;
 664
 665         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
 666                 last_rn = rn;
 667                 rn = 0;
 668
 669                 /*
 670                  * Reset bus and all 1-wire device state machines
 671                  * so they can respond to our requests.
 672                  *
 673                  * Return 0 - device(s) present, 1 - no devices present.
 674                  */
 675                 if (w1_reset_bus(dev)) {
 676                         dev_dbg(&dev->dev, "No devices present on the wire.\n");
 677                         break;
 678                 }
 679
 680                 /* Start the search */
 681                 w1_write_8(dev, W1_SEARCH);
 682                 for (i = 0; i < 64; ++i) {
 683                         /* Determine the direction/search bit */
 684                         if (i == desc_bit)
 685                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
 686                         else if (i > desc_bit)
 687                                 search_bit = 0;   /* take the 0 path on the next branch */
 688                         else
 689                                 search_bit = ((last_rn >> i) & 0x1);
 690
 691                         /** Read two bits and write one bit */
 692                         triplet_ret = w1_triplet(dev, search_bit);
 693
 694                         /* quit if no device responded */
 695                         if ( (triplet_ret & 0x03) == 0x03 )
 696                                 break;
 697
 698                         /* If both directions were valid, and we took the 0 path... */
 699                         if (triplet_ret == 0)
 700                                 last_zero = i;
 701
 702                         /* extract the direction taken & update the device number */
 703                         tmp64 = (triplet_ret >> 2);
 704                         rn |= (tmp64 << i);
 705                 }
 706
 707                 if ( (triplet_ret & 0x03) != 0x03 ) {
 708                         if ( (desc_bit == last_zero) || (last_zero < 0))
 709                                 last_device = 1;
 710                         desc_bit = last_zero;
 711                         cb(dev->bus_master->data, rn);
 712                 }
 713         }
 714 }
 715
 716 static int w1_control(void *data)
 717 {
 718         struct w1_slave *sl, *sln;
 719         struct w1_master *dev, *n;
 720         int err, have_to_wait = 0;
 721
 722         daemonize("w1_control");
 723         allow_signal(SIGTERM);
 724
 725         while (!control_needs_exit || have_to_wait) {
 726                 have_to_wait = 0;
 727
 728                 try_to_freeze();
 729                 msleep_interruptible(w1_control_timeout * 1000);
 730
 731                 if (signal_pending(current))
 732                         flush_signals(current);
 733
 734                 list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
 735                         if (!control_needs_exit && !dev->flags)
 736                                 continue;
 737                         /*
 738                          * Little race: we can create thread but not set the flag.
 739                          * Get a chance for external process to set flag up.
 740                          */
 741                         if (!dev->initialized) {
 742                                 have_to_wait = 1;
 743                                 continue;
 744                         }
 745
 746                         if (control_needs_exit) {
 747                                 set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
 748
 749                                 err = kill_proc(dev->kpid, SIGTERM, 1);
 750                                 if (err)
 751                                         dev_err(&dev->dev,
 752                                                  "Failed to send signal to w1 kernel thread %d.\n",
 753                                                  dev->kpid);
 754                         }
 755
 756                         if (test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
 757                                 wait_for_completion(&dev->dev_exited);
 758                                 spin_lock_bh(&w1_mlock);
 759                                 list_del(&dev->w1_master_entry);
 760                                 spin_unlock_bh(&w1_mlock);
 761
 762                                 down(&dev->mutex);
 763                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 764                                         w1_slave_detach(sl);
 765                                 }
 766                                 w1_destroy_master_attributes(dev);
 767                                 up(&dev->mutex);
 768                                 atomic_dec(&dev->refcnt);
 769                                 continue;
 770                         }
 771
 772                         if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
 773                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
 774                                 down(&dev->mutex);
 775                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 776                                         if (sl->family->fid == W1_FAMILY_DEFAULT) {
 777                                                 struct w1_reg_num rn;
 778
 779                                                 memcpy(&rn, &sl->reg_num, sizeof(rn));
 780                                                 w1_slave_detach(sl);
 781
 782                                                 w1_attach_slave_device(dev, &rn);
 783                                         }
 784                                 }
 785                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
 786                                 clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
 787                                 up(&dev->mutex);
 788                         }
 789                 }
 790         }
 791
 792         complete_and_exit(&w1_control_complete, 0);
 793 }
 794
 795 int w1_process(void *data)
 796 {
 797         struct w1_master *dev = (struct w1_master *) data;
 798         struct w1_slave *sl, *sln;
 799
 800         daemonize("%s", dev->name);
 801         allow_signal(SIGTERM);
 802
 803         while (!test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
 804                 try_to_freeze();
 805                 msleep_interruptible(w1_timeout * 1000);
 806
 807                 if (signal_pending(current))
 808                         flush_signals(current);
 809
 810                 if (test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
 811                         break;
 812
 813                 if (!dev->initialized)
 814                         continue;
 815
 816                 if (dev->search_count == 0)
 817                         continue;
 818
 819                 if (down_interruptible(&dev->mutex))
 820                         continue;
 821
 822                 list_for_each_entry(sl, &dev->slist, w1_slave_entry)
 823                         clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 824
 825                 w1_search_devices(dev, w1_slave_found);
 826
 827                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 828                         if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
 829                                 w1_slave_detach(sl);
 830
 831                                 dev->slave_count--;
 832                         } else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
 833                                 sl->ttl = dev->slave_ttl;
 834                 }
 835
 836                 if (dev->search_count > 0)
 837                         dev->search_count--;
 838
 839                 up(&dev->mutex);
 840         }
 841
 842         atomic_dec(&dev->refcnt);
 843         complete_and_exit(&dev->dev_exited, 0);
 844
 845         return 0;
 846 }
 847
 848 static int w1_init(void)
 849 {
 850         int retval;
 851
 852         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
 853
 854         retval = bus_register(&w1_bus_type);
 855         if (retval) {
 856                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
 857                 goto err_out_exit_init;
 858         }
 859
 860         retval = driver_register(&w1_master_driver);
 861         if (retval) {
 862                 printk(KERN_ERR
 863                         "Failed to register master driver. err=%d.\n",
 864                         retval);
 865                 goto err_out_bus_unregister;
 866         }
 867
 868         retval = driver_register(&w1_slave_driver);
 869         if (retval) {
 870                 printk(KERN_ERR
 871                         "Failed to register master driver. err=%d.\n",
 872                         retval);
 873                 goto err_out_master_unregister;
 874         }
 875
 876         control_thread = kernel_thread(&w1_control, NULL, 0);
 877         if (control_thread < 0) {
 878                 printk(KERN_ERR "Failed to create control thread. err=%d\n",
 879                         control_thread);
 880                 retval = control_thread;
 881                 goto err_out_slave_unregister;
 882         }
 883
 884         return 0;
 885
 886 err_out_slave_unregister:
 887         driver_unregister(&w1_slave_driver);
 888
 889 err_out_master_unregister:
 890         driver_unregister(&w1_master_driver);
 891
 892 err_out_bus_unregister:
 893         bus_unregister(&w1_bus_type);
 894
 895 err_out_exit_init:
 896         return retval;
 897 }
 898
 899 static void w1_fini(void)
 900 {
 901         struct w1_master *dev;
 902
 903         list_for_each_entry(dev, &w1_masters, w1_master_entry)
 904                 __w1_remove_master_device(dev);
 905
 906         control_needs_exit = 1;
 907         wait_for_completion(&w1_control_complete);
 908
 909         driver_unregister(&w1_slave_driver);
 910         driver_unregister(&w1_master_driver);
 911         bus_unregister(&w1_bus_type);
 912 }
 913
 914 module_init(w1_init);
 915 module_exit(w1_fini);