[PATCH] w1: Adds a sysfs entry (w1_master_search) that allows you to disable/enable...
[linux-2.6.git] / drivers / w1 / w1.c
1 /*
2  *      w1.c
3  *
4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
5  *
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21
22 #include <linux/delay.h>
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/moduleparam.h>
26 #include <linux/list.h>
27 #include <linux/interrupt.h>
28 #include <linux/spinlock.h>
29 #include <linux/timer.h>
30 #include <linux/device.h>
31 #include <linux/slab.h>
32 #include <linux/sched.h>
33
34 #include <asm/atomic.h>
35
36 #include "w1.h"
37 #include "w1_io.h"
38 #include "w1_log.h"
39 #include "w1_int.h"
40 #include "w1_family.h"
41 #include "w1_netlink.h"
42
43 MODULE_LICENSE("GPL");
44 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
45 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
46
47 static int w1_timeout = 10;
48 int w1_max_slave_count = 10;
49 int w1_max_slave_ttl = 10;
50
51 module_param_named(timeout, w1_timeout, int, 0);
52 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
53 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
54
55 DEFINE_SPINLOCK(w1_mlock);
56 LIST_HEAD(w1_masters);
57
58 static pid_t control_thread;
59 static int control_needs_exit;
60 static DECLARE_COMPLETION(w1_control_complete);
61
62 static int w1_master_match(struct device *dev, struct device_driver *drv)
63 {
64         return 1;
65 }
66
67 static int w1_master_probe(struct device *dev)
68 {
69         return -ENODEV;
70 }
71
72 static int w1_master_remove(struct device *dev)
73 {
74         return 0;
75 }
76
77 static void w1_master_release(struct device *dev)
78 {
79         struct w1_master *md = container_of(dev, struct w1_master, dev);
80
81         complete(&md->dev_released);
82 }
83
84 static void w1_slave_release(struct device *dev)
85 {
86         struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
87
88         complete(&sl->dev_released);
89 }
90
91 static ssize_t w1_default_read_name(struct device *dev, struct device_attribute *attr, char *buf)
92 {
93         return sprintf(buf, "No family registered.\n");
94 }
95
96 static ssize_t w1_default_read_bin(struct kobject *kobj, char *buf, loff_t off,
97                      size_t count)
98 {
99         return sprintf(buf, "No family registered.\n");
100 }
101
102 static struct device_attribute w1_slave_attribute =
103         __ATTR(name, S_IRUGO, w1_default_read_name, NULL);
104
105 static struct bin_attribute w1_slave_bin_attribute = {
106         .attr = {
107                 .name = "w1_slave",
108                 .mode = S_IRUGO,
109                 .owner = THIS_MODULE,
110         },
111         .size = W1_SLAVE_DATA_SIZE,
112         .read = &w1_default_read_bin,
113 };
114
115
116 static struct bus_type w1_bus_type = {
117         .name = "w1",
118         .match = w1_master_match,
119 };
120
121 struct device_driver w1_driver = {
122         .name = "w1_driver",
123         .bus = &w1_bus_type,
124         .probe = w1_master_probe,
125         .remove = w1_master_remove,
126 };
127
128 struct device w1_device = {
129         .parent = NULL,
130         .bus = &w1_bus_type,
131         .bus_id = "w1 bus master",
132         .driver = &w1_driver,
133         .release = &w1_master_release
134 };
135
136 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
137 {
138         struct w1_master *md = container_of(dev, struct w1_master, dev);
139         ssize_t count;
140
141         if (down_interruptible (&md->mutex))
142                 return -EBUSY;
143
144         count = sprintf(buf, "%s\n", md->name);
145
146         up(&md->mutex);
147
148         return count;
149 }
150
151 static ssize_t w1_master_attribute_store_search(struct device * dev,
152                                                 struct device_attribute *attr,
153                                                 const char * buf, size_t count)
154 {
155         struct w1_master *md = container_of(dev, struct w1_master, dev);
156
157         if (down_interruptible (&md->mutex))
158                 return -EBUSY;
159
160         md->search_count = simple_strtol(buf, NULL, 0);
161
162         up(&md->mutex);
163
164         return count;
165 }
166
167 static ssize_t w1_master_attribute_show_search(struct device *dev,
168                                                struct device_attribute *attr,
169                                                char *buf)
170 {
171         struct w1_master *md = container_of(dev, struct w1_master, dev);
172         ssize_t count;
173
174         if (down_interruptible (&md->mutex))
175                 return -EBUSY;
176
177         count = sprintf(buf, "%d\n", md->search_count);
178
179         up(&md->mutex);
180
181         return count;
182 }
183
184 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
185 {
186         struct w1_master *md = container_of(dev, struct w1_master, dev);
187         ssize_t count;
188
189         if (down_interruptible(&md->mutex))
190                 return -EBUSY;
191
192         count = sprintf(buf, "0x%p\n", md->bus_master);
193
194         up(&md->mutex);
195         return count;
196 }
197
198 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
199 {
200         ssize_t count;
201         count = sprintf(buf, "%d\n", w1_timeout);
202         return count;
203 }
204
205 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
206 {
207         struct w1_master *md = container_of(dev, struct w1_master, dev);
208         ssize_t count;
209
210         if (down_interruptible(&md->mutex))
211                 return -EBUSY;
212
213         count = sprintf(buf, "%d\n", md->max_slave_count);
214
215         up(&md->mutex);
216         return count;
217 }
218
219 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
220 {
221         struct w1_master *md = container_of(dev, struct w1_master, dev);
222         ssize_t count;
223
224         if (down_interruptible(&md->mutex))
225                 return -EBUSY;
226
227         count = sprintf(buf, "%lu\n", md->attempts);
228
229         up(&md->mutex);
230         return count;
231 }
232
233 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
234 {
235         struct w1_master *md = container_of(dev, struct w1_master, dev);
236         ssize_t count;
237
238         if (down_interruptible(&md->mutex))
239                 return -EBUSY;
240
241         count = sprintf(buf, "%d\n", md->slave_count);
242
243         up(&md->mutex);
244         return count;
245 }
246
247 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
248 {
249         struct w1_master *md = container_of(dev, struct w1_master, dev);
250         int c = PAGE_SIZE;
251
252         if (down_interruptible(&md->mutex))
253                 return -EBUSY;
254
255         if (md->slave_count == 0)
256                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
257         else {
258                 struct list_head *ent, *n;
259                 struct w1_slave *sl;
260
261                 list_for_each_safe(ent, n, &md->slist) {
262                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
263
264                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
265                 }
266         }
267
268         up(&md->mutex);
269
270         return PAGE_SIZE - c;
271 }
272
273 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
274         struct device_attribute w1_master_attribute_##_name =   \
275                 __ATTR(w1_master_##_name, _mode,                \
276                        w1_master_attribute_show_##_name, NULL)
277
278 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
279         struct device_attribute w1_master_attribute_##_name =   \
280                 __ATTR(w1_master_##_name, _mode,                \
281                        w1_master_attribute_show_##_name,        \
282                        w1_master_attribute_store_##_name)
283
284 static W1_MASTER_ATTR_RO(name, S_IRUGO);
285 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
286 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
287 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
288 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
289 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
290 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
291 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
292
293 static struct attribute *w1_master_default_attrs[] = {
294         &w1_master_attribute_name.attr,
295         &w1_master_attribute_slaves.attr,
296         &w1_master_attribute_slave_count.attr,
297         &w1_master_attribute_max_slave_count.attr,
298         &w1_master_attribute_attempts.attr,
299         &w1_master_attribute_timeout.attr,
300         &w1_master_attribute_pointer.attr,
301         &w1_master_attribute_search.attr,
302         NULL
303 };
304
305 static struct attribute_group w1_master_defattr_group = {
306         .attrs = w1_master_default_attrs,
307 };
308
309 int w1_create_master_attributes(struct w1_master *master)
310 {
311         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
312 }
313
314 void w1_destroy_master_attributes(struct w1_master *master)
315 {
316         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
317 }
318
319 static int __w1_attach_slave_device(struct w1_slave *sl)
320 {
321         int err;
322
323         sl->dev.parent = &sl->master->dev;
324         sl->dev.driver = sl->master->driver;
325         sl->dev.bus = &w1_bus_type;
326         sl->dev.release = &w1_slave_release;
327
328         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
329                  "%02x-%012llx",
330                  (unsigned int) sl->reg_num.family,
331                  (unsigned long long) sl->reg_num.id);
332         snprintf(&sl->name[0], sizeof(sl->name),
333                  "%02x-%012llx",
334                  (unsigned int) sl->reg_num.family,
335                  (unsigned long long) sl->reg_num.id);
336
337         dev_dbg(&sl->dev, "%s: registering %s.\n", __func__,
338                 &sl->dev.bus_id[0]);
339
340         err = device_register(&sl->dev);
341         if (err < 0) {
342                 dev_err(&sl->dev,
343                         "Device registration [%s] failed. err=%d\n",
344                         sl->dev.bus_id, err);
345                 return err;
346         }
347
348         memcpy(&sl->attr_bin, &w1_slave_bin_attribute, sizeof(sl->attr_bin));
349         memcpy(&sl->attr_name, &w1_slave_attribute, sizeof(sl->attr_name));
350
351         sl->attr_bin.read = sl->family->fops->rbin;
352         sl->attr_name.show = sl->family->fops->rname;
353
354         err = device_create_file(&sl->dev, &sl->attr_name);
355         if (err < 0) {
356                 dev_err(&sl->dev,
357                         "sysfs file creation for [%s] failed. err=%d\n",
358                         sl->dev.bus_id, err);
359                 device_unregister(&sl->dev);
360                 return err;
361         }
362
363         err = sysfs_create_bin_file(&sl->dev.kobj, &sl->attr_bin);
364         if (err < 0) {
365                 dev_err(&sl->dev,
366                         "sysfs file creation for [%s] failed. err=%d\n",
367                         sl->dev.bus_id, err);
368                 device_remove_file(&sl->dev, &sl->attr_name);
369                 device_unregister(&sl->dev);
370                 return err;
371         }
372
373         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
374
375         return 0;
376 }
377
378 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
379 {
380         struct w1_slave *sl;
381         struct w1_family *f;
382         int err;
383         struct w1_netlink_msg msg;
384
385         sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
386         if (!sl) {
387                 dev_err(&dev->dev,
388                          "%s: failed to allocate new slave device.\n",
389                          __func__);
390                 return -ENOMEM;
391         }
392
393         memset(sl, 0, sizeof(*sl));
394
395         sl->owner = THIS_MODULE;
396         sl->master = dev;
397         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
398
399         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
400         atomic_set(&sl->refcnt, 0);
401         init_completion(&sl->dev_released);
402
403         spin_lock(&w1_flock);
404         f = w1_family_registered(rn->family);
405         if (!f) {
406                 spin_unlock(&w1_flock);
407                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
408                           rn->family, rn->family,
409                           (unsigned long long)rn->id, rn->crc);
410                 kfree(sl);
411                 return -ENODEV;
412         }
413         __w1_family_get(f);
414         spin_unlock(&w1_flock);
415
416         sl->family = f;
417
418
419         err = __w1_attach_slave_device(sl);
420         if (err < 0) {
421                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
422                          sl->name);
423                 w1_family_put(sl->family);
424                 kfree(sl);
425                 return err;
426         }
427
428         sl->ttl = dev->slave_ttl;
429         dev->slave_count++;
430
431         memcpy(&msg.id.id, rn, sizeof(msg.id.id));
432         msg.type = W1_SLAVE_ADD;
433         w1_netlink_send(dev, &msg);
434
435         return 0;
436 }
437
438 static void w1_slave_detach(struct w1_slave *sl)
439 {
440         struct w1_netlink_msg msg;
441
442         dev_info(&sl->dev, "%s: detaching %s.\n", __func__, sl->name);
443
444         while (atomic_read(&sl->refcnt)) {
445                 printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n",
446                                 sl->name, atomic_read(&sl->refcnt));
447
448                 if (msleep_interruptible(1000))
449                         flush_signals(current);
450         }
451
452         sysfs_remove_bin_file (&sl->dev.kobj, &sl->attr_bin);
453         device_remove_file(&sl->dev, &sl->attr_name);
454         device_unregister(&sl->dev);
455         w1_family_put(sl->family);
456
457         memcpy(&msg.id.id, &sl->reg_num, sizeof(msg.id.id));
458         msg.type = W1_SLAVE_REMOVE;
459         w1_netlink_send(sl->master, &msg);
460 }
461
462 static struct w1_master *w1_search_master(unsigned long data)
463 {
464         struct w1_master *dev;
465         int found = 0;
466
467         spin_lock_bh(&w1_mlock);
468         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
469                 if (dev->bus_master->data == data) {
470                         found = 1;
471                         atomic_inc(&dev->refcnt);
472                         break;
473                 }
474         }
475         spin_unlock_bh(&w1_mlock);
476
477         return (found)?dev:NULL;
478 }
479
480 static void w1_slave_found(unsigned long data, u64 rn)
481 {
482         int slave_count;
483         struct w1_slave *sl;
484         struct list_head *ent;
485         struct w1_reg_num *tmp;
486         int family_found = 0;
487         struct w1_master *dev;
488
489         dev = w1_search_master(data);
490         if (!dev) {
491                 printk(KERN_ERR "Failed to find w1 master device for data %08lx, it is impossible.\n",
492                                 data);
493                 return;
494         }
495
496         tmp = (struct w1_reg_num *) &rn;
497
498         slave_count = 0;
499         list_for_each(ent, &dev->slist) {
500
501                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
502
503                 if (sl->reg_num.family == tmp->family &&
504                     sl->reg_num.id == tmp->id &&
505                     sl->reg_num.crc == tmp->crc) {
506                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
507                         break;
508                 } else if (sl->reg_num.family == tmp->family) {
509                         family_found = 1;
510                         break;
511                 }
512
513                 slave_count++;
514         }
515
516         rn = cpu_to_le64(rn);
517
518         if (slave_count == dev->slave_count &&
519                 rn && ((le64_to_cpu(rn) >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn, 7)) {
520                 w1_attach_slave_device(dev, tmp);
521         }
522
523         atomic_dec(&dev->refcnt);
524 }
525
526 /**
527  * Performs a ROM Search & registers any devices found.
528  * The 1-wire search is a simple binary tree search.
529  * For each bit of the address, we read two bits and write one bit.
530  * The bit written will put to sleep all devies that don't match that bit.
531  * When the two reads differ, the direction choice is obvious.
532  * When both bits are 0, we must choose a path to take.
533  * When we can scan all 64 bits without having to choose a path, we are done.
534  *
535  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
536  *
537  * @dev        The master device to search
538  * @cb         Function to call when a device is found
539  */
540 void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
541 {
542         u64 last_rn, rn, tmp64;
543         int i, slave_count = 0;
544         int last_zero, last_device;
545         int search_bit, desc_bit;
546         u8  triplet_ret = 0;
547
548         search_bit = 0;
549         rn = last_rn = 0;
550         last_device = 0;
551         last_zero = -1;
552
553         desc_bit = 64;
554
555         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
556                 last_rn = rn;
557                 rn = 0;
558
559                 /*
560                  * Reset bus and all 1-wire device state machines
561                  * so they can respond to our requests.
562                  *
563                  * Return 0 - device(s) present, 1 - no devices present.
564                  */
565                 if (w1_reset_bus(dev)) {
566                         dev_info(&dev->dev, "No devices present on the wire.\n");
567                         break;
568                 }
569
570                 /* Start the search */
571                 w1_write_8(dev, W1_SEARCH);
572                 for (i = 0; i < 64; ++i) {
573                         /* Determine the direction/search bit */
574                         if (i == desc_bit)
575                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
576                         else if (i > desc_bit)
577                                 search_bit = 0;   /* take the 0 path on the next branch */
578                         else
579                                 search_bit = ((last_rn >> i) & 0x1);
580
581                         /** Read two bits and write one bit */
582                         triplet_ret = w1_triplet(dev, search_bit);
583
584                         /* quit if no device responded */
585                         if ( (triplet_ret & 0x03) == 0x03 )
586                                 break;
587
588                         /* If both directions were valid, and we took the 0 path... */
589                         if (triplet_ret == 0)
590                                 last_zero = i;
591
592                         /* extract the direction taken & update the device number */
593                         tmp64 = (triplet_ret >> 2);
594                         rn |= (tmp64 << i);
595                 }
596
597                 if ( (triplet_ret & 0x03) != 0x03 ) {
598                         if ( (desc_bit == last_zero) || (last_zero < 0))
599                                 last_device = 1;
600                         desc_bit = last_zero;
601                         cb(dev->bus_master->data, rn);
602                 }
603         }
604 }
605
606 static int w1_control(void *data)
607 {
608         struct w1_slave *sl, *sln;
609         struct w1_master *dev, *n;
610         int err, have_to_wait = 0;
611
612         daemonize("w1_control");
613         allow_signal(SIGTERM);
614
615         while (!control_needs_exit || have_to_wait) {
616                 have_to_wait = 0;
617
618                 try_to_freeze(PF_FREEZE);
619                 msleep_interruptible(w1_timeout * 1000);
620
621                 if (signal_pending(current))
622                         flush_signals(current);
623
624                 list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
625                         if (!control_needs_exit && !dev->need_exit)
626                                 continue;
627                         /*
628                          * Little race: we can create thread but not set the flag.
629                          * Get a chance for external process to set flag up.
630                          */
631                         if (!dev->initialized) {
632                                 have_to_wait = 1;
633                                 continue;
634                         }
635
636                         spin_lock_bh(&w1_mlock);
637                         list_del(&dev->w1_master_entry);
638                         spin_unlock_bh(&w1_mlock);
639
640                         if (control_needs_exit) {
641                                 dev->need_exit = 1;
642
643                                 err = kill_proc(dev->kpid, SIGTERM, 1);
644                                 if (err)
645                                         dev_err(&dev->dev,
646                                                  "Failed to send signal to w1 kernel thread %d.\n",
647                                                  dev->kpid);
648                         }
649
650                         wait_for_completion(&dev->dev_exited);
651
652                         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
653                                 list_del(&sl->w1_slave_entry);
654
655                                 w1_slave_detach(sl);
656                                 kfree(sl);
657                         }
658                         w1_destroy_master_attributes(dev);
659                         atomic_dec(&dev->refcnt);
660                 }
661         }
662
663         complete_and_exit(&w1_control_complete, 0);
664 }
665
666 int w1_process(void *data)
667 {
668         struct w1_master *dev = (struct w1_master *) data;
669         struct w1_slave *sl, *sln;
670
671         daemonize("%s", dev->name);
672         allow_signal(SIGTERM);
673
674         while (!dev->need_exit) {
675                 try_to_freeze(PF_FREEZE);
676                 msleep_interruptible(w1_timeout * 1000);
677
678                 if (signal_pending(current))
679                         flush_signals(current);
680
681                 if (dev->need_exit)
682                         break;
683
684                 if (!dev->initialized)
685                         continue;
686
687                 if (dev->search_count == 0)
688                         continue;
689
690                 if (down_interruptible(&dev->mutex))
691                         continue;
692
693                 list_for_each_entry(sl, &dev->slist, w1_slave_entry)
694                         clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
695
696                 w1_search_devices(dev, w1_slave_found);
697
698                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
699                         if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
700                                 list_del (&sl->w1_slave_entry);
701
702                                 w1_slave_detach (sl);
703                                 kfree (sl);
704
705                                 dev->slave_count--;
706                         } else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
707                                 sl->ttl = dev->slave_ttl;
708                 }
709
710                 if (dev->search_count > 0)
711                         dev->search_count--;
712
713                 up(&dev->mutex);
714         }
715
716         atomic_dec(&dev->refcnt);
717         complete_and_exit(&dev->dev_exited, 0);
718
719         return 0;
720 }
721
722 static int w1_init(void)
723 {
724         int retval;
725
726         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
727
728         retval = bus_register(&w1_bus_type);
729         if (retval) {
730                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
731                 goto err_out_exit_init;
732         }
733
734         retval = driver_register(&w1_driver);
735         if (retval) {
736                 printk(KERN_ERR
737                         "Failed to register master driver. err=%d.\n",
738                         retval);
739                 goto err_out_bus_unregister;
740         }
741
742         control_thread = kernel_thread(&w1_control, NULL, 0);
743         if (control_thread < 0) {
744                 printk(KERN_ERR "Failed to create control thread. err=%d\n",
745                         control_thread);
746                 retval = control_thread;
747                 goto err_out_driver_unregister;
748         }
749
750         return 0;
751
752 err_out_driver_unregister:
753         driver_unregister(&w1_driver);
754
755 err_out_bus_unregister:
756         bus_unregister(&w1_bus_type);
757
758 err_out_exit_init:
759         return retval;
760 }
761
762 static void w1_fini(void)
763 {
764         struct w1_master *dev;
765
766         list_for_each_entry(dev, &w1_masters, w1_master_entry)
767                 __w1_remove_master_device(dev);
768
769         control_needs_exit = 1;
770         wait_for_completion(&w1_control_complete);
771
772         driver_unregister(&w1_driver);
773         bus_unregister(&w1_bus_type);
774 }
775
776 module_init(w1_init);
777 module_exit(w1_fini);