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 #include <linux/kthread.h>
  34 #include <linux/freezer.h>
  35
  36 #include <asm/atomic.h>
  37
  38 #include "w1.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 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(max_slave_count, w1_max_slave_count, int, 0);
  54 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
  55
  56 DEFINE_MUTEX(w1_mlock);
  57 LIST_HEAD(w1_masters);
  58
  59 static int w1_master_match(struct device *dev, struct device_driver *drv)
  60 {
  61         return 1;
  62 }
  63
  64 static int w1_master_probe(struct device *dev)
  65 {
  66         return -ENODEV;
  67 }
  68
  69 static void w1_master_release(struct device *dev)
  70 {
  71         struct w1_master *md = dev_to_w1_master(dev);
  72
  73         dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
  74         memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
  75         kfree(md);
  76 }
  77
  78 static void w1_slave_release(struct device *dev)
  79 {
  80         struct w1_slave *sl = dev_to_w1_slave(dev);
  81
  82         printk("%s: Releasing %s.\n", __func__, sl->name);
  83
  84         while (atomic_read(&sl->refcnt)) {
  85                 printk("Waiting for %s to become free: refcnt=%d.\n",
  86                                 sl->name, atomic_read(&sl->refcnt));
  87                 if (msleep_interruptible(1000))
  88                         flush_signals(current);
  89         }
  90
  91         w1_family_put(sl->family);
  92         sl->master->slave_count--;
  93
  94         complete(&sl->released);
  95 }
  96
  97 static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
  98 {
  99         struct w1_slave *sl = dev_to_w1_slave(dev);
 100
 101         return sprintf(buf, "%s\n", sl->name);
 102 }
 103
 104 static ssize_t w1_slave_read_id(struct kobject *kobj,
 105                                 struct bin_attribute *bin_attr,
 106                                 char *buf, loff_t off, size_t count)
 107 {
 108         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 109
 110         if (off > 8) {
 111                 count = 0;
 112         } else {
 113                 if (off + count > 8)
 114                         count = 8 - off;
 115
 116                 memcpy(buf, (u8 *)&sl->reg_num, count);
 117         }
 118
 119         return count;
 120 }
 121
 122 static struct device_attribute w1_slave_attr_name =
 123         __ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
 124
 125 static struct bin_attribute w1_slave_attr_bin_id = {
 126       .attr = {
 127               .name = "id",
 128               .mode = S_IRUGO,
 129       },
 130       .size = 8,
 131       .read = w1_slave_read_id,
 132 };
 133
 134 /* Default family */
 135
 136 static ssize_t w1_default_write(struct kobject *kobj,
 137                                 struct bin_attribute *bin_attr,
 138                                 char *buf, loff_t off, size_t count)
 139 {
 140         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 141
 142         mutex_lock(&sl->master->mutex);
 143         if (w1_reset_select_slave(sl)) {
 144                 count = 0;
 145                 goto out_up;
 146         }
 147
 148         w1_write_block(sl->master, buf, count);
 149
 150 out_up:
 151         mutex_unlock(&sl->master->mutex);
 152         return count;
 153 }
 154
 155 static ssize_t w1_default_read(struct kobject *kobj,
 156                                struct bin_attribute *bin_attr,
 157                                char *buf, loff_t off, size_t count)
 158 {
 159         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 160
 161         mutex_lock(&sl->master->mutex);
 162         w1_read_block(sl->master, buf, count);
 163         mutex_unlock(&sl->master->mutex);
 164         return count;
 165 }
 166
 167 static struct bin_attribute w1_default_attr = {
 168       .attr = {
 169               .name = "rw",
 170               .mode = S_IRUGO | S_IWUSR,
 171       },
 172       .size = PAGE_SIZE,
 173       .read = w1_default_read,
 174       .write = w1_default_write,
 175 };
 176
 177 static int w1_default_add_slave(struct w1_slave *sl)
 178 {
 179         return sysfs_create_bin_file(&sl->dev.kobj, &w1_default_attr);
 180 }
 181
 182 static void w1_default_remove_slave(struct w1_slave *sl)
 183 {
 184         sysfs_remove_bin_file(&sl->dev.kobj, &w1_default_attr);
 185 }
 186
 187 static struct w1_family_ops w1_default_fops = {
 188         .add_slave      = w1_default_add_slave,
 189         .remove_slave   = w1_default_remove_slave,
 190 };
 191
 192 static struct w1_family w1_default_family = {
 193         .fops = &w1_default_fops,
 194 };
 195
 196 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env);
 197
 198 static struct bus_type w1_bus_type = {
 199         .name = "w1",
 200         .match = w1_master_match,
 201         .uevent = w1_uevent,
 202 };
 203
 204 struct device_driver w1_master_driver = {
 205         .name = "w1_master_driver",
 206         .bus = &w1_bus_type,
 207         .probe = w1_master_probe,
 208 };
 209
 210 struct device w1_master_device = {
 211         .parent = NULL,
 212         .bus = &w1_bus_type,
 213         .bus_id = "w1 bus master",
 214         .driver = &w1_master_driver,
 215         .release = &w1_master_release
 216 };
 217
 218 static struct device_driver w1_slave_driver = {
 219         .name = "w1_slave_driver",
 220         .bus = &w1_bus_type,
 221 };
 222
 223 #if 0
 224 struct device w1_slave_device = {
 225         .parent = NULL,
 226         .bus = &w1_bus_type,
 227         .bus_id = "w1 bus slave",
 228         .driver = &w1_slave_driver,
 229         .release = &w1_slave_release
 230 };
 231 #endif  /*  0  */
 232
 233 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
 234 {
 235         struct w1_master *md = dev_to_w1_master(dev);
 236         ssize_t count;
 237
 238         mutex_lock(&md->mutex);
 239         count = sprintf(buf, "%s\n", md->name);
 240         mutex_unlock(&md->mutex);
 241
 242         return count;
 243 }
 244
 245 static ssize_t w1_master_attribute_store_search(struct device * dev,
 246                                                 struct device_attribute *attr,
 247                                                 const char * buf, size_t count)
 248 {
 249         long tmp;
 250         struct w1_master *md = dev_to_w1_master(dev);
 251
 252         if (strict_strtol(buf, 0, &tmp) == -EINVAL)
 253                 return -EINVAL;
 254
 255         mutex_lock(&md->mutex);
 256         md->search_count = tmp;
 257         mutex_unlock(&md->mutex);
 258         wake_up_process(md->thread);
 259
 260         return count;
 261 }
 262
 263 static ssize_t w1_master_attribute_show_search(struct device *dev,
 264                                                struct device_attribute *attr,
 265                                                char *buf)
 266 {
 267         struct w1_master *md = dev_to_w1_master(dev);
 268         ssize_t count;
 269
 270         mutex_lock(&md->mutex);
 271         count = sprintf(buf, "%d\n", md->search_count);
 272         mutex_unlock(&md->mutex);
 273
 274         return count;
 275 }
 276
 277 static ssize_t w1_master_attribute_store_pullup(struct device *dev,
 278                                                 struct device_attribute *attr,
 279                                                 const char *buf, size_t count)
 280 {
 281         long tmp;
 282         struct w1_master *md = dev_to_w1_master(dev);
 283
 284         if (strict_strtol(buf, 0, &tmp) == -EINVAL)
 285                 return -EINVAL;
 286
 287         mutex_lock(&md->mutex);
 288         md->enable_pullup = tmp;
 289         mutex_unlock(&md->mutex);
 290         wake_up_process(md->thread);
 291
 292         return count;
 293 }
 294
 295 static ssize_t w1_master_attribute_show_pullup(struct device *dev,
 296                                                struct device_attribute *attr,
 297                                                char *buf)
 298 {
 299         struct w1_master *md = dev_to_w1_master(dev);
 300         ssize_t count;
 301
 302         mutex_lock(&md->mutex);
 303         count = sprintf(buf, "%d\n", md->enable_pullup);
 304         mutex_unlock(&md->mutex);
 305
 306         return count;
 307 }
 308
 309 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
 310 {
 311         struct w1_master *md = dev_to_w1_master(dev);
 312         ssize_t count;
 313
 314         mutex_lock(&md->mutex);
 315         count = sprintf(buf, "0x%p\n", md->bus_master);
 316         mutex_unlock(&md->mutex);
 317         return count;
 318 }
 319
 320 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
 321 {
 322         ssize_t count;
 323         count = sprintf(buf, "%d\n", w1_timeout);
 324         return count;
 325 }
 326
 327 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 328 {
 329         struct w1_master *md = dev_to_w1_master(dev);
 330         ssize_t count;
 331
 332         mutex_lock(&md->mutex);
 333         count = sprintf(buf, "%d\n", md->max_slave_count);
 334         mutex_unlock(&md->mutex);
 335         return count;
 336 }
 337
 338 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
 339 {
 340         struct w1_master *md = dev_to_w1_master(dev);
 341         ssize_t count;
 342
 343         mutex_lock(&md->mutex);
 344         count = sprintf(buf, "%lu\n", md->attempts);
 345         mutex_unlock(&md->mutex);
 346         return count;
 347 }
 348
 349 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
 350 {
 351         struct w1_master *md = dev_to_w1_master(dev);
 352         ssize_t count;
 353
 354         mutex_lock(&md->mutex);
 355         count = sprintf(buf, "%d\n", md->slave_count);
 356         mutex_unlock(&md->mutex);
 357         return count;
 358 }
 359
 360 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
 361 {
 362         struct w1_master *md = dev_to_w1_master(dev);
 363         int c = PAGE_SIZE;
 364
 365         mutex_lock(&md->mutex);
 366
 367         if (md->slave_count == 0)
 368                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
 369         else {
 370                 struct list_head *ent, *n;
 371                 struct w1_slave *sl;
 372
 373                 list_for_each_safe(ent, n, &md->slist) {
 374                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 375
 376                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
 377                 }
 378         }
 379
 380         mutex_unlock(&md->mutex);
 381
 382         return PAGE_SIZE - c;
 383 }
 384
 385 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
 386         struct device_attribute w1_master_attribute_##_name =   \
 387                 __ATTR(w1_master_##_name, _mode,                \
 388                        w1_master_attribute_show_##_name, NULL)
 389
 390 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
 391         struct device_attribute w1_master_attribute_##_name =   \
 392                 __ATTR(w1_master_##_name, _mode,                \
 393                        w1_master_attribute_show_##_name,        \
 394                        w1_master_attribute_store_##_name)
 395
 396 static W1_MASTER_ATTR_RO(name, S_IRUGO);
 397 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
 398 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
 399 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
 400 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
 401 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
 402 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
 403 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
 404 static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUGO);
 405
 406 static struct attribute *w1_master_default_attrs[] = {
 407         &w1_master_attribute_name.attr,
 408         &w1_master_attribute_slaves.attr,
 409         &w1_master_attribute_slave_count.attr,
 410         &w1_master_attribute_max_slave_count.attr,
 411         &w1_master_attribute_attempts.attr,
 412         &w1_master_attribute_timeout.attr,
 413         &w1_master_attribute_pointer.attr,
 414         &w1_master_attribute_search.attr,
 415         &w1_master_attribute_pullup.attr,
 416         NULL
 417 };
 418
 419 static struct attribute_group w1_master_defattr_group = {
 420         .attrs = w1_master_default_attrs,
 421 };
 422
 423 int w1_create_master_attributes(struct w1_master *master)
 424 {
 425         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
 426 }
 427
 428 void w1_destroy_master_attributes(struct w1_master *master)
 429 {
 430         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
 431 }
 432
 433 #ifdef CONFIG_HOTPLUG
 434 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
 435 {
 436         struct w1_master *md = NULL;
 437         struct w1_slave *sl = NULL;
 438         char *event_owner, *name;
 439         int err;
 440
 441         if (dev->driver == &w1_master_driver) {
 442                 md = container_of(dev, struct w1_master, dev);
 443                 event_owner = "master";
 444                 name = md->name;
 445         } else if (dev->driver == &w1_slave_driver) {
 446                 sl = container_of(dev, struct w1_slave, dev);
 447                 event_owner = "slave";
 448                 name = sl->name;
 449         } else {
 450                 dev_dbg(dev, "Unknown event.\n");
 451                 return -EINVAL;
 452         }
 453
 454         dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
 455                         event_owner, name, dev->bus_id);
 456
 457         if (dev->driver != &w1_slave_driver || !sl)
 458                 return 0;
 459
 460         err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
 461         if (err)
 462                 return err;
 463
 464         err = add_uevent_var(env, "W1_SLAVE_ID=%024LX",
 465                              (unsigned long long)sl->reg_num.id);
 466         if (err)
 467                 return err;
 468
 469         return 0;
 470 };
 471 #else
 472 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
 473 {
 474         return 0;
 475 }
 476 #endif
 477
 478 static int __w1_attach_slave_device(struct w1_slave *sl)
 479 {
 480         int err;
 481
 482         sl->dev.parent = &sl->master->dev;
 483         sl->dev.driver = &w1_slave_driver;
 484         sl->dev.bus = &w1_bus_type;
 485         sl->dev.release = &w1_slave_release;
 486
 487         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
 488                  "%02x-%012llx",
 489                  (unsigned int) sl->reg_num.family,
 490                  (unsigned long long) sl->reg_num.id);
 491         snprintf(&sl->name[0], sizeof(sl->name),
 492                  "%02x-%012llx",
 493                  (unsigned int) sl->reg_num.family,
 494                  (unsigned long long) sl->reg_num.id);
 495
 496         dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
 497                 &sl->dev.bus_id[0], sl);
 498
 499         err = device_register(&sl->dev);
 500         if (err < 0) {
 501                 dev_err(&sl->dev,
 502                         "Device registration [%s] failed. err=%d\n",
 503                         sl->dev.bus_id, err);
 504                 return err;
 505         }
 506
 507         /* Create "name" entry */
 508         err = device_create_file(&sl->dev, &w1_slave_attr_name);
 509         if (err < 0) {
 510                 dev_err(&sl->dev,
 511                         "sysfs file creation for [%s] failed. err=%d\n",
 512                         sl->dev.bus_id, err);
 513                 goto out_unreg;
 514         }
 515
 516         /* Create "id" entry */
 517         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 518         if (err < 0) {
 519                 dev_err(&sl->dev,
 520                         "sysfs file creation for [%s] failed. err=%d\n",
 521                         sl->dev.bus_id, err);
 522                 goto out_rem1;
 523         }
 524
 525         /* if the family driver needs to initialize something... */
 526         if (sl->family->fops && sl->family->fops->add_slave &&
 527             ((err = sl->family->fops->add_slave(sl)) < 0)) {
 528                 dev_err(&sl->dev,
 529                         "sysfs file creation for [%s] failed. err=%d\n",
 530                         sl->dev.bus_id, err);
 531                 goto out_rem2;
 532         }
 533
 534         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
 535
 536         return 0;
 537
 538 out_rem2:
 539         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 540 out_rem1:
 541         device_remove_file(&sl->dev, &w1_slave_attr_name);
 542 out_unreg:
 543         device_unregister(&sl->dev);
 544         return err;
 545 }
 546
 547 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
 548 {
 549         struct w1_slave *sl;
 550         struct w1_family *f;
 551         int err;
 552         struct w1_netlink_msg msg;
 553
 554         sl = kzalloc(sizeof(struct w1_slave), GFP_KERNEL);
 555         if (!sl) {
 556                 dev_err(&dev->dev,
 557                          "%s: failed to allocate new slave device.\n",
 558                          __func__);
 559                 return -ENOMEM;
 560         }
 561
 562
 563         sl->owner = THIS_MODULE;
 564         sl->master = dev;
 565         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 566
 567         memset(&msg, 0, sizeof(msg));
 568         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
 569         atomic_set(&sl->refcnt, 0);
 570         init_completion(&sl->released);
 571
 572         spin_lock(&w1_flock);
 573         f = w1_family_registered(rn->family);
 574         if (!f) {
 575                 f= &w1_default_family;
 576                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
 577                           rn->family, rn->family,
 578                           (unsigned long long)rn->id, rn->crc);
 579         }
 580         __w1_family_get(f);
 581         spin_unlock(&w1_flock);
 582
 583         sl->family = f;
 584
 585
 586         err = __w1_attach_slave_device(sl);
 587         if (err < 0) {
 588                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
 589                          sl->name);
 590                 w1_family_put(sl->family);
 591                 kfree(sl);
 592                 return err;
 593         }
 594
 595         sl->ttl = dev->slave_ttl;
 596         dev->slave_count++;
 597
 598         memcpy(msg.id.id, rn, sizeof(msg.id));
 599         msg.type = W1_SLAVE_ADD;
 600         w1_netlink_send(dev, &msg);
 601
 602         return 0;
 603 }
 604
 605 void w1_slave_detach(struct w1_slave *sl)
 606 {
 607         struct w1_netlink_msg msg;
 608
 609         dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
 610
 611         list_del(&sl->w1_slave_entry);
 612
 613         if (sl->family->fops && sl->family->fops->remove_slave)
 614                 sl->family->fops->remove_slave(sl);
 615
 616         memset(&msg, 0, sizeof(msg));
 617         memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
 618         msg.type = W1_SLAVE_REMOVE;
 619         w1_netlink_send(sl->master, &msg);
 620
 621         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
 622         device_remove_file(&sl->dev, &w1_slave_attr_name);
 623         device_unregister(&sl->dev);
 624
 625         wait_for_completion(&sl->released);
 626         kfree(sl);
 627 }
 628
 629 struct w1_master *w1_search_master_id(u32 id)
 630 {
 631         struct w1_master *dev;
 632         int found = 0;
 633
 634         mutex_lock(&w1_mlock);
 635         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 636                 if (dev->id == id) {
 637                         found = 1;
 638                         atomic_inc(&dev->refcnt);
 639                         break;
 640                 }
 641         }
 642         mutex_unlock(&w1_mlock);
 643
 644         return (found)?dev:NULL;
 645 }
 646
 647 struct w1_slave *w1_search_slave(struct w1_reg_num *id)
 648 {
 649         struct w1_master *dev;
 650         struct w1_slave *sl = NULL;
 651         int found = 0;
 652
 653         mutex_lock(&w1_mlock);
 654         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 655                 mutex_lock(&dev->mutex);
 656                 list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
 657                         if (sl->reg_num.family == id->family &&
 658                                         sl->reg_num.id == id->id &&
 659                                         sl->reg_num.crc == id->crc) {
 660                                 found = 1;
 661                                 atomic_inc(&dev->refcnt);
 662                                 atomic_inc(&sl->refcnt);
 663                                 break;
 664                         }
 665                 }
 666                 mutex_unlock(&dev->mutex);
 667
 668                 if (found)
 669                         break;
 670         }
 671         mutex_unlock(&w1_mlock);
 672
 673         return (found)?sl:NULL;
 674 }
 675
 676 void w1_reconnect_slaves(struct w1_family *f, int attach)
 677 {
 678         struct w1_slave *sl, *sln;
 679         struct w1_master *dev;
 680
 681         mutex_lock(&w1_mlock);
 682         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 683                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
 684                         "for family %02x.\n", dev->name, f->fid);
 685                 mutex_lock(&dev->mutex);
 686                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 687                         /* If it is a new family, slaves with the default
 688                          * family driver and are that family will be
 689                          * connected.  If the family is going away, devices
 690                          * matching that family are reconneced.
 691                          */
 692                         if ((attach && sl->family->fid == W1_FAMILY_DEFAULT
 693                                 && sl->reg_num.family == f->fid) ||
 694                                 (!attach && sl->family->fid == f->fid)) {
 695                                 struct w1_reg_num rn;
 696
 697                                 memcpy(&rn, &sl->reg_num, sizeof(rn));
 698                                 w1_slave_detach(sl);
 699
 700                                 w1_attach_slave_device(dev, &rn);
 701                         }
 702                 }
 703                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
 704                         "has been finished.\n", dev->name);
 705                 mutex_unlock(&dev->mutex);
 706         }
 707         mutex_unlock(&w1_mlock);
 708 }
 709
 710 static void w1_slave_found(struct w1_master *dev, u64 rn)
 711 {
 712         int slave_count;
 713         struct w1_slave *sl;
 714         struct list_head *ent;
 715         struct w1_reg_num *tmp;
 716         u64 rn_le = cpu_to_le64(rn);
 717
 718         atomic_inc(&dev->refcnt);
 719
 720         tmp = (struct w1_reg_num *) &rn;
 721
 722         slave_count = 0;
 723         list_for_each(ent, &dev->slist) {
 724
 725                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
 726
 727                 if (sl->reg_num.family == tmp->family &&
 728                     sl->reg_num.id == tmp->id &&
 729                     sl->reg_num.crc == tmp->crc) {
 730                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 731                         break;
 732                 }
 733
 734                 slave_count++;
 735         }
 736
 737         if (slave_count == dev->slave_count &&
 738                 rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
 739                 w1_attach_slave_device(dev, tmp);
 740         }
 741
 742         atomic_dec(&dev->refcnt);
 743 }
 744
 745 /**
 746  * Performs a ROM Search & registers any devices found.
 747  * The 1-wire search is a simple binary tree search.
 748  * For each bit of the address, we read two bits and write one bit.
 749  * The bit written will put to sleep all devies that don't match that bit.
 750  * When the two reads differ, the direction choice is obvious.
 751  * When both bits are 0, we must choose a path to take.
 752  * When we can scan all 64 bits without having to choose a path, we are done.
 753  *
 754  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
 755  *
 756  * @dev        The master device to search
 757  * @cb         Function to call when a device is found
 758  */
 759 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
 760 {
 761         u64 last_rn, rn, tmp64;
 762         int i, slave_count = 0;
 763         int last_zero, last_device;
 764         int search_bit, desc_bit;
 765         u8  triplet_ret = 0;
 766
 767         search_bit = 0;
 768         rn = last_rn = 0;
 769         last_device = 0;
 770         last_zero = -1;
 771
 772         desc_bit = 64;
 773
 774         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
 775                 last_rn = rn;
 776                 rn = 0;
 777
 778                 /*
 779                  * Reset bus and all 1-wire device state machines
 780                  * so they can respond to our requests.
 781                  *
 782                  * Return 0 - device(s) present, 1 - no devices present.
 783                  */
 784                 if (w1_reset_bus(dev)) {
 785                         dev_dbg(&dev->dev, "No devices present on the wire.\n");
 786                         break;
 787                 }
 788
 789                 /* Start the search */
 790                 w1_write_8(dev, search_type);
 791                 for (i = 0; i < 64; ++i) {
 792                         /* Determine the direction/search bit */
 793                         if (i == desc_bit)
 794                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
 795                         else if (i > desc_bit)
 796                                 search_bit = 0;   /* take the 0 path on the next branch */
 797                         else
 798                                 search_bit = ((last_rn >> i) & 0x1);
 799
 800                         /** Read two bits and write one bit */
 801                         triplet_ret = w1_triplet(dev, search_bit);
 802
 803                         /* quit if no device responded */
 804                         if ( (triplet_ret & 0x03) == 0x03 )
 805                                 break;
 806
 807                         /* If both directions were valid, and we took the 0 path... */
 808                         if (triplet_ret == 0)
 809                                 last_zero = i;
 810
 811                         /* extract the direction taken & update the device number */
 812                         tmp64 = (triplet_ret >> 2);
 813                         rn |= (tmp64 << i);
 814
 815                         if (kthread_should_stop()) {
 816                                 printk(KERN_INFO "Abort w1_search (exiting)\n");
 817                                 return;
 818                         }
 819                 }
 820
 821                 if ( (triplet_ret & 0x03) != 0x03 ) {
 822                         if ( (desc_bit == last_zero) || (last_zero < 0))
 823                                 last_device = 1;
 824                         desc_bit = last_zero;
 825                         cb(dev, rn);
 826                 }
 827         }
 828 }
 829
 830 void w1_search_process(struct w1_master *dev, u8 search_type)
 831 {
 832         struct w1_slave *sl, *sln;
 833
 834         list_for_each_entry(sl, &dev->slist, w1_slave_entry)
 835                 clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
 836
 837         w1_search_devices(dev, search_type, w1_slave_found);
 838
 839         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 840                 if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl)
 841                         w1_slave_detach(sl);
 842                 else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
 843                         sl->ttl = dev->slave_ttl;
 844         }
 845
 846         if (dev->search_count > 0)
 847                 dev->search_count--;
 848 }
 849
 850 int w1_process(void *data)
 851 {
 852         struct w1_master *dev = (struct w1_master *) data;
 853         /* As long as w1_timeout is only set by a module parameter the sleep
 854          * time can be calculated in jiffies once.
 855          */
 856         const unsigned long jtime = msecs_to_jiffies(w1_timeout * 1000);
 857
 858         while (!kthread_should_stop()) {
 859                 if (dev->search_count) {
 860                         mutex_lock(&dev->mutex);
 861                         w1_search_process(dev, W1_SEARCH);
 862                         mutex_unlock(&dev->mutex);
 863                 }
 864
 865                 try_to_freeze();
 866                 __set_current_state(TASK_INTERRUPTIBLE);
 867
 868                 if (kthread_should_stop())
 869                         break;
 870
 871                 /* Only sleep when the search is active. */
 872                 if (dev->search_count)
 873                         schedule_timeout(jtime);
 874                 else
 875                         schedule();
 876         }
 877
 878         atomic_dec(&dev->refcnt);
 879
 880         return 0;
 881 }
 882
 883 static int w1_init(void)
 884 {
 885         int retval;
 886
 887         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
 888
 889         w1_init_netlink();
 890
 891         retval = bus_register(&w1_bus_type);
 892         if (retval) {
 893                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
 894                 goto err_out_exit_init;
 895         }
 896
 897         retval = driver_register(&w1_master_driver);
 898         if (retval) {
 899                 printk(KERN_ERR
 900                         "Failed to register master driver. err=%d.\n",
 901                         retval);
 902                 goto err_out_bus_unregister;
 903         }
 904
 905         retval = driver_register(&w1_slave_driver);
 906         if (retval) {
 907                 printk(KERN_ERR
 908                         "Failed to register master driver. err=%d.\n",
 909                         retval);
 910                 goto err_out_master_unregister;
 911         }
 912
 913         return 0;
 914
 915 #if 0
 916 /* For undoing the slave register if there was a step after it. */
 917 err_out_slave_unregister:
 918         driver_unregister(&w1_slave_driver);
 919 #endif
 920
 921 err_out_master_unregister:
 922         driver_unregister(&w1_master_driver);
 923
 924 err_out_bus_unregister:
 925         bus_unregister(&w1_bus_type);
 926
 927 err_out_exit_init:
 928         return retval;
 929 }
 930
 931 static void w1_fini(void)
 932 {
 933         struct w1_master *dev;
 934
 935         /* Set netlink removal messages and some cleanup */
 936         list_for_each_entry(dev, &w1_masters, w1_master_entry)
 937                 __w1_remove_master_device(dev);
 938
 939         w1_fini_netlink();
 940
 941         driver_unregister(&w1_slave_driver);
 942         driver_unregister(&w1_master_driver);
 943         bus_unregister(&w1_bus_type);
 944 }
 945
 946 module_init(w1_init);
 947 module_exit(w1_fini);