aboutsummaryrefslogtreecommitdiff
path: root/drivers/w1/w1.c
blob: d640c1e1f8cdc77dac3ac23dd86547a338710b3c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
/*
 *	w1.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/sched.h>

#include <asm/atomic.h>

#include "w1.h"
#include "w1_io.h"
#include "w1_log.h"
#include "w1_int.h"
#include "w1_family.h"
#include "w1_netlink.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");

static int w1_timeout = 10;
static int w1_control_timeout = 1;
int w1_max_slave_count = 10;
int w1_max_slave_ttl = 10;

module_param_named(timeout, w1_timeout, int, 0);
module_param_named(control_timeout, w1_control_timeout, int, 0);
module_param_named(max_slave_count, w1_max_slave_count, int, 0);
module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);

DEFINE_SPINLOCK(w1_mlock);
LIST_HEAD(w1_masters);

static pid_t control_thread;
static int control_needs_exit;
static DECLARE_COMPLETION(w1_control_complete);

static int w1_master_match(struct device *dev, struct device_driver *drv)
{
	return 1;
}

static int w1_master_probe(struct device *dev)
{
	return -ENODEV;
}

static void w1_master_release(struct device *dev)
{
	struct w1_master *md = dev_to_w1_master(dev);

	dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);

	dev_fini_netlink(md);
	memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
	kfree(md);
}

static void w1_slave_release(struct device *dev)
{
	struct w1_slave *sl = dev_to_w1_slave(dev);

	dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name);

	while (atomic_read(&sl->refcnt)) {
		dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n",
				sl->name, atomic_read(&sl->refcnt));
		if (msleep_interruptible(1000))
			flush_signals(current);
	}

	w1_family_put(sl->family);
	sl->master->slave_count--;

	complete(&sl->released);
}

static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_slave *sl = dev_to_w1_slave(dev);

	return sprintf(buf, "%s\n", sl->name);
}

static ssize_t w1_slave_read_id(struct kobject *kobj, char *buf, loff_t off, size_t count)
{
	struct w1_slave *sl = kobj_to_w1_slave(kobj);

	atomic_inc(&sl->refcnt);
	if (off > 8) {
		count = 0;
	} else {
		if (off + count > 8)
			count = 8 - off;

		memcpy(buf, (u8 *)&sl->reg_num, count);
	}
	atomic_dec(&sl->refcnt);

	return count;
}

static struct device_attribute w1_slave_attr_name =
	__ATTR(name, S_IRUGO, w1_slave_read_name, NULL);

static struct bin_attribute w1_slave_attr_bin_id = {
      .attr = {
              .name = "id",
              .mode = S_IRUGO,
              .owner = THIS_MODULE,
      },
      .size = 8,
      .read = w1_slave_read_id,
};

/* Default family */
static struct w1_family w1_default_family;

static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size);

static struct bus_type w1_bus_type = {
	.name = "w1",
	.match = w1_master_match,
	.uevent = w1_uevent,
};

struct device_driver w1_master_driver = {
	.name = "w1_master_driver",
	.bus = &w1_bus_type,
	.probe = w1_master_probe,
};

struct device w1_master_device = {
	.parent = NULL,
	.bus = &w1_bus_type,
	.bus_id = "w1 bus master",
	.driver = &w1_master_driver,
	.release = &w1_master_release
};

static struct device_driver w1_slave_driver = {
	.name = "w1_slave_driver",
	.bus = &w1_bus_type,
};

#if 0
struct device w1_slave_device = {
	.parent = NULL,
	.bus = &w1_bus_type,
	.bus_id = "w1 bus slave",
	.driver = &w1_slave_driver,
	.release = &w1_slave_release
};
#endif  /*  0  */

static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	if (down_interruptible (&md->mutex))
		return -EBUSY;

	count = sprintf(buf, "%s\n", md->name);

	up(&md->mutex);

	return count;
}

static ssize_t w1_master_attribute_store_search(struct device * dev,
						struct device_attribute *attr,
						const char * buf, size_t count)
{
	struct w1_master *md = dev_to_w1_master(dev);

	if (down_interruptible (&md->mutex))
		return -EBUSY;

	md->search_count = simple_strtol(buf, NULL, 0);

	up(&md->mutex);

	return count;
}

static ssize_t w1_master_attribute_show_search(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	if (down_interruptible (&md->mutex))
		return -EBUSY;

	count = sprintf(buf, "%d\n", md->search_count);

	up(&md->mutex);

	return count;
}

static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	if (down_interruptible(&md->mutex))
		return -EBUSY;

	count = sprintf(buf, "0x%p\n", md->bus_master);

	up(&md->mutex);
	return count;
}

static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
{
	ssize_t count;
	count = sprintf(buf, "%d\n", w1_timeout);
	return count;
}

static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	if (down_interruptible(&md->mutex))
		return -EBUSY;

	count = sprintf(buf, "%d\n", md->max_slave_count);

	up(&md->mutex);
	return count;
}

static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	if (down_interruptible(&md->mutex))
		return -EBUSY;

	count = sprintf(buf, "%lu\n", md->attempts);

	up(&md->mutex);
	return count;
}

static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	if (down_interruptible(&md->mutex))
		return -EBUSY;

	count = sprintf(buf, "%d\n", md->slave_count);

	up(&md->mutex);
	return count;
}

static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	int c = PAGE_SIZE;

	if (down_interruptible(&md->mutex))
		return -EBUSY;

	if (md->slave_count == 0)
		c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
	else {
		struct list_head *ent, *n;
		struct w1_slave *sl;

		list_for_each_safe(ent, n, &md->slist) {
			sl = list_entry(ent, struct w1_slave, w1_slave_entry);

			c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
		}
	}

	up(&md->mutex);

	return PAGE_SIZE - c;
}

#define W1_MASTER_ATTR_RO(_name, _mode)				\
	struct device_attribute w1_master_attribute_##_name =	\
		__ATTR(w1_master_##_name, _mode,		\
		       w1_master_attribute_show_##_name, NULL)

#define W1_MASTER_ATTR_RW(_name, _mode)				\
	struct device_attribute w1_master_attribute_##_name =	\
		__ATTR(w1_master_##_name, _mode,		\
		       w1_master_attribute_show_##_name,	\
		       w1_master_attribute_store_##_name)

static W1_MASTER_ATTR_RO(name, S_IRUGO);
static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);

static struct attribute *w1_master_default_attrs[] = {
	&w1_master_attribute_name.attr,
	&w1_master_attribute_slaves.attr,
	&w1_master_attribute_slave_count.attr,
	&w1_master_attribute_max_slave_count.attr,
	&w1_master_attribute_attempts.attr,
	&w1_master_attribute_timeout.attr,
	&w1_master_attribute_pointer.attr,
	&w1_master_attribute_search.attr,
	NULL
};

static struct attribute_group w1_master_defattr_group = {
	.attrs = w1_master_default_attrs,
};

int w1_create_master_attributes(struct w1_master *master)
{
	return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
}

static void w1_destroy_master_attributes(struct w1_master *master)
{
	sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
}

#ifdef CONFIG_HOTPLUG
static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
{
	struct w1_master *md = NULL;
	struct w1_slave *sl = NULL;
	char *event_owner, *name;
	int err, cur_index=0, cur_len=0;

	if (dev->driver == &w1_master_driver) {
		md = container_of(dev, struct w1_master, dev);
		event_owner = "master";
		name = md->name;
	} else if (dev->driver == &w1_slave_driver) {
		sl = container_of(dev, struct w1_slave, dev);
		event_owner = "slave";
		name = sl->name;
	} else {
		dev_dbg(dev, "Unknown event.\n");
		return -EINVAL;
	}

	dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n", event_owner, name, dev->bus_id);

	if (dev->driver != &w1_slave_driver || !sl)
		return 0;

	err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
			&cur_len, "W1_FID=%02X", sl->reg_num.family);
	if (err)
		return err;

	err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
			&cur_len, "W1_SLAVE_ID=%024LX",
			(unsigned long long)sl->reg_num.id);
	if (err)
		return err;

	return 0;
};
#else
static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
{
	return 0;
}
#endif

static int __w1_attach_slave_device(struct w1_slave *sl)
{
	int err;

	sl->dev.parent = &sl->master->dev;
	sl->dev.driver = &w1_slave_driver;
	sl->dev.bus = &w1_bus_type;
	sl->dev.release = &w1_slave_release;

	snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
		 "%02x-%012llx",
		 (unsigned int) sl->reg_num.family,
		 (unsigned long long) sl->reg_num.id);
	snprintf(&sl->name[0], sizeof(sl->name),
		 "%02x-%012llx",
		 (unsigned int) sl->reg_num.family,
		 (unsigned long long) sl->reg_num.id);

	dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__, &sl->dev.bus_id[0]);

	err = device_register(&sl->dev);
	if (err < 0) {
		dev_err(&sl->dev,
			"Device registration [%s] failed. err=%d\n",
			sl->dev.bus_id, err);
		return err;
	}

	/* Create "name" entry */
	err = device_create_file(&sl->dev, &w1_slave_attr_name);
	if (err < 0) {
		dev_err(&sl->dev,
			"sysfs file creation for [%s] failed. err=%d\n",
			sl->dev.bus_id, err);
		goto out_unreg;
	}

	/* Create "id" entry */
	err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
	if (err < 0) {
		dev_err(&sl->dev,
			"sysfs file creation for [%s] failed. err=%d\n",
			sl->dev.bus_id, err);
		goto out_rem1;
	}

	/* if the family driver needs to initialize something... */
	if (sl->family->fops && sl->family->fops->add_slave &&
	    ((err = sl->family->fops->add_slave(sl)) < 0)) {
		dev_err(&sl->dev,
			"sysfs file creation for [%s] failed. err=%d\n",
			sl->dev.bus_id, err);
		goto out_rem2;
	}

	list_add_tail(&sl->w1_slave_entry, &sl->master->slist);

	return 0;

out_rem2:
	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
out_rem1:
	device_remove_file(&sl->dev, &w1_slave_attr_name);
out_unreg:
	device_unregister(&sl->dev);
	return err;
}

static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
{
	struct w1_slave *sl;
	struct w1_family *f;
	int err;
	struct w1_netlink_msg msg;

	sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
	if (!sl) {
		dev_err(&dev->dev,
			 "%s: failed to allocate new slave device.\n",
			 __func__);
		return -ENOMEM;
	}

	memset(sl, 0, sizeof(*sl));

	sl->owner = THIS_MODULE;
	sl->master = dev;
	set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);

	memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
	atomic_set(&sl->refcnt, 0);
	init_completion(&sl->released);

	spin_lock(&w1_flock);
	f = w1_family_registered(rn->family);
	if (!f) {
		f= &w1_default_family;
		dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
			  rn->family, rn->family,
			  (unsigned long long)rn->id, rn->crc);
	}
	__w1_family_get(f);
	spin_unlock(&w1_flock);

	sl->family = f;


	err = __w1_attach_slave_device(sl);
	if (err < 0) {
		dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
			 sl->name);
		w1_family_put(sl->family);
		kfree(sl);
		return err;
	}

	sl->ttl = dev->slave_ttl;
	dev->slave_count++;

	memcpy(&msg.id.id, rn, sizeof(msg.id.id));
	msg.type = W1_SLAVE_ADD;
	w1_netlink_send(dev, &msg);

	return 0;
}

static void w1_slave_detach(struct w1_slave *sl)
{
	struct w1_netlink_msg msg;

	dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);

	list_del(&sl->w1_slave_entry);

	if (sl->family->fops && sl->family->fops->remove_slave)
		sl->family->fops->remove_slave(sl);

	memcpy(&msg.id.id, &sl->reg_num, sizeof(msg.id.id));
	msg.type = W1_SLAVE_REMOVE;
	w1_netlink_send(sl->master, &msg);

	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
	device_remove_file(&sl->dev, &w1_slave_attr_name);
	device_unregister(&sl->dev);

	wait_for_completion(&sl->released);
	kfree(sl);
}

static struct w1_master *w1_search_master(void *data)
{
	struct w1_master *dev;
	int found = 0;

	spin_lock_bh(&w1_mlock);
	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
		if (dev->bus_master->data == data) {
			found = 1;
			atomic_inc(&dev->refcnt);
			break;
		}
	}
	spin_unlock_bh(&w1_mlock);

	return (found)?dev:NULL;
}

void w1_reconnect_slaves(struct w1_family *f)
{
	struct w1_master *dev;

	spin_lock_bh(&w1_mlock);
	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
		dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
				dev->name, f->fid);
		set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
	}
	spin_unlock_bh(&w1_mlock);
}

static void w1_slave_found(void *data, u64 rn)
{
	int slave_count;
	struct w1_slave *sl;
	struct list_head *ent;
	struct w1_reg_num *tmp;
	int family_found = 0;
	struct w1_master *dev;
	u64 rn_le = cpu_to_le64(rn);

	dev = w1_search_master(data);
	if (!dev) {
		printk(KERN_ERR "Failed to find w1 master device for data %p, "
		       "it is impossible.\n", data);
		return;
	}

	tmp = (struct w1_reg_num *) &rn;

	slave_count = 0;
	list_for_each(ent, &dev->slist) {

		sl = list_entry(ent, struct w1_slave, w1_slave_entry);

		if (sl->reg_num.family == tmp->family &&
		    sl->reg_num.id == tmp->id &&
		    sl->reg_num.crc == tmp->crc) {
			set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
			break;
		} else if (sl->reg_num.family == tmp->family) {
			family_found = 1;
			break;
		}

		slave_count++;
	}

	if (slave_count == dev->slave_count &&
		rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
		w1_attach_slave_device(dev, tmp);
	}

	atomic_dec(&dev->refcnt);
}

/**
 * Performs a ROM Search & registers any devices found.
 * The 1-wire search is a simple binary tree search.
 * For each bit of the address, we read two bits and write one bit.
 * The bit written will put to sleep all devies that don't match that bit.
 * When the two reads differ, the direction choice is obvious.
 * When both bits are 0, we must choose a path to take.
 * When we can scan all 64 bits without having to choose a path, we are done.
 *
 * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
 *
 * @dev        The master device to search
 * @cb         Function to call when a device is found
 */
void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
{
	u64 last_rn, rn, tmp64;
	int i, slave_count = 0;
	int last_zero, last_device;
	int search_bit, desc_bit;
	u8  triplet_ret = 0;

	search_bit = 0;
	rn = last_rn = 0;
	last_device = 0;
	last_zero = -1;

	desc_bit = 64;

	while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
		last_rn = rn;
		rn = 0;

		/*
		 * Reset bus and all 1-wire device state machines
		 * so they can respond to our requests.
		 *
		 * Return 0 - device(s) present, 1 - no devices present.
		 */
		if (w1_reset_bus(dev)) {
			dev_dbg(&dev->dev, "No devices present on the wire.\n");
			break;
		}

		/* Start the search */
		w1_write_8(dev, W1_SEARCH);
		for (i = 0; i < 64; ++i) {
			/* Determine the direction/search bit */
			if (i == desc_bit)
				search_bit = 1;	  /* took the 0 path last time, so take the 1 path */
			else if (i > desc_bit)
				search_bit = 0;	  /* take the 0 path on the next branch */
			else
				search_bit = ((last_rn >> i) & 0x1);

			/** Read two bits and write one bit */
			triplet_ret = w1_triplet(dev, search_bit);

			/* quit if no device responded */
			if ( (triplet_ret & 0x03) == 0x03 )
				break;

			/* If both directions were valid, and we took the 0 path... */
			if (triplet_ret == 0)
				last_zero = i;

			/* extract the direction taken & update the device number */
			tmp64 = (triplet_ret >> 2);
			rn |= (tmp64 << i);
		}

		if ( (triplet_ret & 0x03) != 0x03 ) {
			if ( (desc_bit == last_zero) || (last_zero < 0))
				last_device = 1;
			desc_bit = last_zero;
			cb(dev->bus_master->data, rn);
		}
	}
}

static int w1_control(void *data)
{
	struct w1_slave *sl, *sln;
	struct w1_master *dev, *n;
	int err, have_to_wait = 0;

	daemonize("w1_control");
	allow_signal(SIGTERM);

	while (!control_needs_exit || have_to_wait) {
		have_to_wait = 0;

		try_to_freeze();
		msleep_interruptible(w1_control_timeout * 1000);

		if (signal_pending(current))
			flush_signals(current);

		list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
			if (!control_needs_exit && !dev->flags)
				continue;
			/*
			 * Little race: we can create thread but not set the flag.
			 * Get a chance for external process to set flag up.
			 */
			if (!dev->initialized) {
				have_to_wait = 1;
				continue;
			}

			if (control_needs_exit) {
				set_bit(W1_MASTER_NEED_EXIT, &dev->flags);

				err = kill_proc(dev->kpid, SIGTERM, 1);
				if (err)
					dev_err(&dev->dev,
						 "Failed to send signal to w1 kernel thread %d.\n",
						 dev->kpid);
			}

			if (test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
				wait_for_completion(&dev->dev_exited);
				spin_lock_bh(&w1_mlock);
				list_del(&dev->w1_master_entry);
				spin_unlock_bh(&w1_mlock);

				down(&dev->mutex);
				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
					w1_slave_detach(sl);
				}
				w1_destroy_master_attributes(dev);
				up(&dev->mutex);
				atomic_dec(&dev->refcnt);
				continue;
			}

			if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
				dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
				down(&dev->mutex);
				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
					if (sl->family->fid == W1_FAMILY_DEFAULT) {
						struct w1_reg_num rn;

						memcpy(&rn, &sl->reg_num, sizeof(rn));
						w1_slave_detach(sl);

						w1_attach_slave_device(dev, &rn);
					}
				}
				dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
				clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
				up(&dev->mutex);
			}
		}
	}

	complete_and_exit(&w1_control_complete, 0);
}

int w1_process(void *data)
{
	struct w1_master *dev = (struct w1_master *) data;
	struct w1_slave *sl, *sln;

	daemonize("%s", dev->name);
	allow_signal(SIGTERM);

	while (!test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
		try_to_freeze();
		msleep_interruptible(w1_timeout * 1000);

		if (signal_pending(current))
			flush_signals(current);

		if (test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
			break;

		if (!dev->initialized)
			continue;

		if (dev->search_count == 0)
			continue;

		if (down_interruptible(&dev->mutex))
			continue;

		list_for_each_entry(sl, &dev->slist, w1_slave_entry)
			clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);

		w1_search_devices(dev, w1_slave_found);

		list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
			if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
				w1_slave_detach(sl);

				dev->slave_count--;
			} else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
				sl->ttl = dev->slave_ttl;
		}

		if (dev->search_count > 0)
			dev->search_count--;

		up(&dev->mutex);
	}

	atomic_dec(&dev->refcnt);
	complete_and_exit(&dev->dev_exited, 0);

	return 0;
}

static int w1_init(void)
{
	int retval;

	printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");

	retval = bus_register(&w1_bus_type);
	if (retval) {
		printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
		goto err_out_exit_init;
	}

	retval = driver_register(&w1_master_driver);
	if (retval) {
		printk(KERN_ERR
			"Failed to register master driver. err=%d.\n",
			retval);
		goto err_out_bus_unregister;
	}

	retval = driver_register(&w1_slave_driver);
	if (retval) {
		printk(KERN_ERR
			"Failed to register master driver. err=%d.\n",
			retval);
		goto err_out_master_unregister;
	}

	control_thread = kernel_thread(&w1_control, NULL, 0);
	if (control_thread < 0) {
		printk(KERN_ERR "Failed to create control thread. err=%d\n",
			control_thread);
		retval = control_thread;
		goto err_out_slave_unregister;
	}

	return 0;

err_out_slave_unregister:
	driver_unregister(&w1_slave_driver);

err_out_master_unregister:
	driver_unregister(&w1_master_driver);

err_out_bus_unregister:
	bus_unregister(&w1_bus_type);

err_out_exit_init:
	return retval;
}

static void w1_fini(void)
{
	struct w1_master *dev;

	list_for_each_entry(dev, &w1_masters, w1_master_entry)
		__w1_remove_master_device(dev);

	control_needs_exit = 1;
	wait_for_completion(&w1_control_complete);

	driver_unregister(&w1_slave_driver);
	driver_unregister(&w1_master_driver);
	bus_unregister(&w1_bus_type);
}

module_init(w1_init);
module_exit(w1_fini);