summaryrefslogtreecommitdiffstats
path: root/drivers/w1/w1.c
blob: 8172dee5e23cffd5d031acf786eae1e77d198409 (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
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
/*
 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 *
 * 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.
 */

#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 <linux/kthread.h>
#include <linux/freezer.h>

#include <linux/atomic.h>

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

static int w1_timeout = 10;
module_param_named(timeout, w1_timeout, int, 0);
MODULE_PARM_DESC(timeout, "time in seconds between automatic slave searches");

static int w1_timeout_us = 0;
module_param_named(timeout_us, w1_timeout_us, int, 0);
MODULE_PARM_DESC(timeout_us,
		 "time in microseconds between automatic slave searches");

/* A search stops when w1_max_slave_count devices have been found in that
 * search.  The next search will start over and detect the same set of devices
 * on a static 1-wire bus.  Memory is not allocated based on this number, just
 * on the number of devices known to the kernel.  Having a high number does not
 * consume additional resources.  As a special case, if there is only one
 * device on the network and w1_max_slave_count is set to 1, the device id can
 * be read directly skipping the normal slower search process.
 */
int w1_max_slave_count = 64;
module_param_named(max_slave_count, w1_max_slave_count, int, 0);
MODULE_PARM_DESC(max_slave_count,
	"maximum number of slaves detected in a search");

int w1_max_slave_ttl = 10;
module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
MODULE_PARM_DESC(slave_ttl,
	"Number of searches not seeing a slave before it will be removed");

DEFINE_MUTEX(w1_mlock);
LIST_HEAD(w1_masters);

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);
	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 [%p]\n", __func__, sl->name, sl);

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

static ssize_t name_show(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 DEVICE_ATTR_RO(name);

static ssize_t id_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	struct w1_slave *sl = dev_to_w1_slave(dev);
	ssize_t count = sizeof(sl->reg_num);

	memcpy(buf, (u8 *)&sl->reg_num, count);
	return count;
}
static DEVICE_ATTR_RO(id);

static struct attribute *w1_slave_attrs[] = {
	&dev_attr_name.attr,
	&dev_attr_id.attr,
	NULL,
};
ATTRIBUTE_GROUPS(w1_slave);

/* Default family */

static ssize_t rw_write(struct file *filp, struct kobject *kobj,
			struct bin_attribute *bin_attr, char *buf, loff_t off,
			size_t count)
{
	struct w1_slave *sl = kobj_to_w1_slave(kobj);

	mutex_lock(&sl->master->mutex);
	if (w1_reset_select_slave(sl)) {
		count = 0;
		goto out_up;
	}

	w1_write_block(sl->master, buf, count);

out_up:
	mutex_unlock(&sl->master->mutex);
	return count;
}

static ssize_t rw_read(struct file *filp, struct kobject *kobj,
		       struct bin_attribute *bin_attr, char *buf, loff_t off,
		       size_t count)
{
	struct w1_slave *sl = kobj_to_w1_slave(kobj);

	mutex_lock(&sl->master->mutex);
	w1_read_block(sl->master, buf, count);
	mutex_unlock(&sl->master->mutex);
	return count;
}

static BIN_ATTR_RW(rw, PAGE_SIZE);

static struct bin_attribute *w1_slave_bin_attrs[] = {
	&bin_attr_rw,
	NULL,
};

static const struct attribute_group w1_slave_default_group = {
	.bin_attrs = w1_slave_bin_attrs,
};

static const struct attribute_group *w1_slave_default_groups[] = {
	&w1_slave_default_group,
	NULL,
};

static struct w1_family_ops w1_default_fops = {
	.groups		= w1_slave_default_groups,
};

static struct w1_family w1_default_family = {
	.fops = &w1_default_fops,
};

static int w1_uevent(struct device *dev, struct kobj_uevent_env *env);

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,
	.init_name = "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,
	.init_name = "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;

	mutex_lock(&md->mutex);
	count = sprintf(buf, "%s\n", md->name);
	mutex_unlock(&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)
{
	long tmp;
	struct w1_master *md = dev_to_w1_master(dev);
	int ret;

	ret = kstrtol(buf, 0, &tmp);
	if (ret)
		return ret;

	mutex_lock(&md->mutex);
	md->search_count = tmp;
	mutex_unlock(&md->mutex);
	/* Only wake if it is going to be searching. */
	if (tmp)
		wake_up_process(md->thread);

	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;

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

	return count;
}

static ssize_t w1_master_attribute_store_pullup(struct device *dev,
						struct device_attribute *attr,
						const char *buf, size_t count)
{
	long tmp;
	struct w1_master *md = dev_to_w1_master(dev);
	int ret;

	ret = kstrtol(buf, 0, &tmp);
	if (ret)
		return ret;

	mutex_lock(&md->mutex);
	md->enable_pullup = tmp;
	mutex_unlock(&md->mutex);

	return count;
}

static ssize_t w1_master_attribute_show_pullup(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	struct w1_master *md = dev_to_w1_master(dev);
	ssize_t count;

	mutex_lock(&md->mutex);
	count = sprintf(buf, "%d\n", md->enable_pullup);
	mutex_unlock(&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;

	mutex_lock(&md->mutex);
	count = sprintf(buf, "0x%p\n", md->bus_master);
	mutex_unlock(&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_timeout_us(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	ssize_t count;
	count = sprintf(buf, "%d\n", w1_timeout_us);
	return count;
}

static ssize_t w1_master_attribute_store_max_slave_count(struct device *dev,
	struct device_attribute *attr, const char *buf, size_t count)
{
	int tmp;
	struct w1_master *md = dev_to_w1_master(dev);

	if (kstrtoint(buf, 0, &tmp) || tmp < 1)
		return -EINVAL;

	mutex_lock(&md->mutex);
	md->max_slave_count = tmp;
	/* allow each time the max_slave_count is updated */
	clear_bit(W1_WARN_MAX_COUNT, &md->flags);
	mutex_unlock(&md->mutex);

	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;

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

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

	mutex_lock(&md->mutex);
	count = sprintf(buf, "%d\n", md->slave_count);
	mutex_unlock(&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;
	struct list_head *ent, *n;
	struct w1_slave *sl = NULL;

	mutex_lock(&md->list_mutex);

	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);
	}
	if (!sl)
		c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");

	mutex_unlock(&md->list_mutex);

	return PAGE_SIZE - c;
}

static ssize_t w1_master_attribute_show_add(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	int c = PAGE_SIZE;
	c -= snprintf(buf+PAGE_SIZE - c, c,
		"write device id xx-xxxxxxxxxxxx to add slave\n");
	return PAGE_SIZE - c;
}

static int w1_atoreg_num(struct device *dev, const char *buf, size_t count,
	struct w1_reg_num *rn)
{
	unsigned int family;
	unsigned long long id;
	int i;
	u64 rn64_le;

	/* The CRC value isn't read from the user because the sysfs directory
	 * doesn't include it and most messages from the bus search don't
	 * print it either.  It would be unreasonable for the user to then
	 * provide it.
	 */
	const char *error_msg = "bad slave string format, expecting "
		"ff-dddddddddddd\n";

	if (buf[2] != '-') {
		dev_err(dev, "%s", error_msg);
		return -EINVAL;
	}
	i = sscanf(buf, "%02x-%012llx", &family, &id);
	if (i != 2) {
		dev_err(dev, "%s", error_msg);
		return -EINVAL;
	}
	rn->family = family;
	rn->id = id;

	rn64_le = cpu_to_le64(*(u64 *)rn);
	rn->crc = w1_calc_crc8((u8 *)&rn64_le, 7);

#if 0
	dev_info(dev, "With CRC device is %02x.%012llx.%02x.\n",
		  rn->family, (unsigned long long)rn->id, rn->crc);
#endif

	return 0;
}

/* Searches the slaves in the w1_master and returns a pointer or NULL.
 * Note: must not hold list_mutex
 */
struct w1_slave *w1_slave_search_device(struct w1_master *dev,
	struct w1_reg_num *rn)
{
	struct w1_slave *sl;
	mutex_lock(&dev->list_mutex);
	list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
		if (sl->reg_num.family == rn->family &&
				sl->reg_num.id == rn->id &&
				sl->reg_num.crc == rn->crc) {
			mutex_unlock(&dev->list_mutex);
			return sl;
		}
	}
	mutex_unlock(&dev->list_mutex);
	return NULL;
}

static ssize_t w1_master_attribute_store_add(struct device *dev,
						struct device_attribute *attr,
						const char *buf, size_t count)
{
	struct w1_master *md = dev_to_w1_master(dev);
	struct w1_reg_num rn;
	struct w1_slave *sl;
	ssize_t result = count;

	if (w1_atoreg_num(dev, buf, count, &rn))
		return -EINVAL;

	mutex_lock(&md->mutex);
	sl = w1_slave_search_device(md, &rn);
	/* It would be nice to do a targeted search one the one-wire bus
	 * for the new device to see if it is out there or not.  But the
	 * current search doesn't support that.
	 */
	if (sl) {
		dev_info(dev, "Device %s already exists\n", sl->name);
		result = -EINVAL;
	} else {
		w1_attach_slave_device(md, &rn);
	}
	mutex_unlock(&md->mutex);

	return result;
}

static ssize_t w1_master_attribute_show_remove(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	int c = PAGE_SIZE;
	c -= snprintf(buf+PAGE_SIZE - c, c,
		"write device id xx-xxxxxxxxxxxx to remove slave\n");
	return PAGE_SIZE - c;
}

static ssize_t w1_master_attribute_store_remove(struct device *dev,
						struct device_attribute *attr,
						const char *buf, size_t count)
{
	struct w1_master *md = dev_to_w1_master(dev);
	struct w1_reg_num rn;
	struct w1_slave *sl;
	ssize_t result = count;

	if (w1_atoreg_num(dev, buf, count, &rn))
		return -EINVAL;

	mutex_lock(&md->mutex);
	sl = w1_slave_search_device(md, &rn);
	if (sl) {
		result = w1_slave_detach(sl);
		/* refcnt 0 means it was detached in the call */
		if (result == 0)
			result = count;
	} else {
		dev_info(dev, "Device %02x-%012llx doesn't exists\n", rn.family,
			(unsigned long long)rn.id);
		result = -EINVAL;
	}
	mutex_unlock(&md->mutex);

	return result;
}

#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_RW(max_slave_count, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
static W1_MASTER_ATTR_RO(timeout_us, S_IRUGO);
static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(add, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(remove, S_IRUGO | S_IWUSR | S_IWGRP);

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_timeout_us.attr,
	&w1_master_attribute_pointer.attr,
	&w1_master_attribute_search.attr,
	&w1_master_attribute_pullup.attr,
	&w1_master_attribute_add.attr,
	&w1_master_attribute_remove.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);
}

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

static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct w1_master *md = NULL;
	struct w1_slave *sl = NULL;
	char *event_owner, *name;
	int err = 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_name(dev));

	if (dev->driver != &w1_slave_driver || !sl)
		goto end;

	err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
	if (err)
		goto end;

	err = add_uevent_var(env, "W1_SLAVE_ID=%024LX",
			     (unsigned long long)sl->reg_num.id);
end:
	return err;
}

static int w1_family_notify(unsigned long action, struct w1_slave *sl)
{
	struct w1_family_ops *fops;
	int err;

	fops = sl->family->fops;

	if (!fops)
		return 0;

	switch (action) {
	case BUS_NOTIFY_ADD_DEVICE:
		/* if the family driver needs to initialize something... */
		if (fops->add_slave) {
			err = fops->add_slave(sl);
			if (err < 0) {
				dev_err(&sl->dev,
					"add_slave() call failed. err=%d\n",
					err);
				return err;
			}
		}
		if (fops->groups) {
			err = sysfs_create_groups(&sl->dev.kobj, fops->groups);
			if (err) {
				dev_err(&sl->dev,
					"sysfs group creation failed. err=%d\n",
					err);
				return err;
			}
		}

		break;
	case BUS_NOTIFY_DEL_DEVICE:
		if (fops->remove_slave)
			sl->family->fops->remove_slave(sl);
		if (fops->groups)
			sysfs_remove_groups(&sl->dev.kobj, fops->groups);
		break;
	}
	return 0;
}

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;
	sl->dev.groups = w1_slave_groups;

	dev_set_name(&sl->dev, "%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__,
		dev_name(&sl->dev), sl);

	/* suppress for w1_family_notify before sending KOBJ_ADD */
	dev_set_uevent_suppress(&sl->dev, true);

	err = device_register(&sl->dev);
	if (err < 0) {
		dev_err(&sl->dev,
			"Device registration [%s] failed. err=%d\n",
			dev_name(&sl->dev), err);
		return err;
	}
	w1_family_notify(BUS_NOTIFY_ADD_DEVICE, sl);

	dev_set_uevent_suppress(&sl->dev, false);
	kobject_uevent(&sl->dev.kobj, KOBJ_ADD);

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

	return 0;
}

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


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

	memset(&msg, 0, sizeof(msg));
	memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
	atomic_set(&sl->refcnt, 1);
	atomic_inc(&sl->master->refcnt);

	/* slave modules need to be loaded in a context with unlocked mutex */
	mutex_unlock(&dev->mutex);
	request_module("w1-family-0x%02x", rn->family);
	mutex_lock(&dev->mutex);

	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);
		atomic_dec(&sl->master->refcnt);
		kfree(sl);
		return err;
	}

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

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

	return 0;
}

int w1_unref_slave(struct w1_slave *sl)
{
	struct w1_master *dev = sl->master;
	int refcnt;
	mutex_lock(&dev->list_mutex);
	refcnt = atomic_sub_return(1, &sl->refcnt);
	if (refcnt == 0) {
		struct w1_netlink_msg msg;

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

		list_del(&sl->w1_slave_entry);

		memset(&msg, 0, sizeof(msg));
		memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
		msg.type = W1_SLAVE_REMOVE;
		w1_netlink_send(sl->master, &msg);

		w1_family_notify(BUS_NOTIFY_DEL_DEVICE, sl);
		device_unregister(&sl->dev);
		#ifdef DEBUG
		memset(sl, 0, sizeof(*sl));
		#endif
		kfree(sl);
	}
	atomic_dec(&dev->refcnt);
	mutex_unlock(&dev->list_mutex);
	return refcnt;
}

int w1_slave_detach(struct w1_slave *sl)
{
	/* Only detach a slave once as it decreases the refcnt each time. */
	int destroy_now;
	mutex_lock(&sl->master->list_mutex);
	destroy_now = !test_bit(W1_SLAVE_DETACH, &sl->flags);
	set_bit(W1_SLAVE_DETACH, &sl->flags);
	mutex_unlock(&sl->master->list_mutex);

	if (destroy_now)
		destroy_now = !w1_unref_slave(sl);
	return destroy_now ? 0 : -EBUSY;
}

struct w1_master *w1_search_master_id(u32 id)
{
	struct w1_master *dev;
	int found = 0;

	mutex_lock(&w1_mlock);
	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
		if (dev->id == id) {
			found = 1;
			atomic_inc(&dev->refcnt);
			break;
		}
	}
	mutex_unlock(&w1_mlock);

	return (found)?dev:NULL;
}

struct w1_slave *w1_search_slave(struct w1_reg_num *id)
{
	struct w1_master *dev;
	struct w1_slave *sl = NULL;
	int found = 0;

	mutex_lock(&w1_mlock);
	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
		mutex_lock(&dev->list_mutex);
		list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
			if (sl->reg_num.family == id->family &&
					sl->reg_num.id == id->id &&
					sl->reg_num.crc == id->crc) {
				found = 1;
				atomic_inc(&dev->refcnt);
				atomic_inc(&sl->refcnt);
				break;
			}
		}
		mutex_unlock(&dev->list_mutex);

		if (found)
			break;
	}
	mutex_unlock(&w1_mlock);

	return (found)?sl:NULL;
}

void w1_reconnect_slaves(struct w1_family *f, int attach)
{
	struct w1_slave *sl, *sln;
	struct w1_master *dev;

	mutex_lock(&w1_mlock);
	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
		dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
			"for family %02x.\n", dev->name, f->fid);
		mutex_lock(&dev->mutex);
		mutex_lock(&dev->list_mutex);
		list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
			/* If it is a new family, slaves with the default
			 * family driver and are that family will be
			 * connected.  If the family is going away, devices
			 * matching that family are reconneced.
			 */
			if ((attach && sl->family->fid == W1_FAMILY_DEFAULT
				&& sl->reg_num.family == f->fid) ||
				(!attach && sl->family->fid == f->fid)) {
				struct w1_reg_num rn;

				mutex_unlock(&dev->list_mutex);
				memcpy(&rn, &sl->reg_num, sizeof(rn));
				/* If it was already in use let the automatic
				 * scan pick it up again later.
				 */
				if (!w1_slave_detach(sl))
					w1_attach_slave_device(dev, &rn);
				mutex_lock(&dev->list_mutex);
			}
		}
		dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
			"has been finished.\n", dev->name);
		mutex_unlock(&dev->list_mutex);
		mutex_unlock(&dev->mutex);
	}
	mutex_unlock(&w1_mlock);
}

void w1_slave_found(struct w1_master *dev, u64 rn)
{
	struct w1_slave *sl;
	struct w1_reg_num *tmp;
	u64 rn_le = cpu_to_le64(rn);

	atomic_inc(&dev->refcnt);

	tmp = (struct w1_reg_num *) &rn;

	sl = w1_slave_search_device(dev, tmp);
	if (sl) {
		set_bit(W1_SLAVE_ACTIVE, &sl->flags);
	} else {
		if (rn && tmp->crc == w1_calc_crc8((u8 *)&rn_le, 7))
			w1_attach_slave_device(dev, tmp);
	}

	atomic_dec(&dev->refcnt);
}

/**
 * w1_search() - Performs a ROM Search & registers any devices found.
 * @dev: The master device to search
 * @search_type: W1_SEARCH to search all devices, or W1_ALARM_SEARCH
 * to return only devices in the alarmed state
 * @cb: Function to call when a device is 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
 *
 */
void w1_search(struct w1_master *dev, u8 search_type, 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 = dev->search_id;
	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.
		 */
		mutex_lock(&dev->bus_mutex);
		if (w1_reset_bus(dev)) {
			mutex_unlock(&dev->bus_mutex);
			dev_dbg(&dev->dev, "No devices present on the wire.\n");
			break;
		}

		/* Do fast search on single slave bus */
		if (dev->max_slave_count == 1) {
			int rv;
			w1_write_8(dev, W1_READ_ROM);
			rv = w1_read_block(dev, (u8 *)&rn, 8);
			mutex_unlock(&dev->bus_mutex);

			if (rv == 8 && rn)
				cb(dev, rn);

			break;
		}

		/* Start the search */
		w1_write_8(dev, search_type);
		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 (test_bit(W1_ABORT_SEARCH, &dev->flags)) {
				mutex_unlock(&dev->bus_mutex);
				dev_dbg(&dev->dev, "Abort w1_search\n");
				return;
			}
		}
		mutex_unlock(&dev->bus_mutex);

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

		if (!last_device && slave_count == dev->max_slave_count &&
			!test_bit(W1_WARN_MAX_COUNT, &dev->flags)) {
			/* Only max_slave_count will be scanned in a search,
			 * but it will start where it left off next search
			 * until all ids are identified and then it will start
			 * over.  A continued search will report the previous
			 * last id as the first id (provided it is still on the
			 * bus).
			 */
			dev_info(&dev->dev, "%s: max_slave_count %d reached, "
				"will continue next search.\n", __func__,
				dev->max_slave_count);
			set_bit(W1_WARN_MAX_COUNT, &dev->flags);
		}
	}
}

void w1_search_process_cb(struct w1_master *dev, u8 search_type,
	w1_slave_found_callback cb)
{
	struct w1_slave *sl, *sln;

	mutex_lock(&dev->list_mutex);
	list_for_each_entry(sl, &dev->slist, w1_slave_entry)
		clear_bit(W1_SLAVE_ACTIVE, &sl->flags);
	mutex_unlock(&dev->list_mutex);

	w1_search_devices(dev, search_type, cb);

	mutex_lock(&dev->list_mutex);
	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
		if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) {
			mutex_unlock(&dev->list_mutex);
			w1_slave_detach(sl);
			mutex_lock(&dev->list_mutex);
		}
		else if (test_bit(W1_SLAVE_ACTIVE, &sl->flags))
			sl->ttl = dev->slave_ttl;
	}
	mutex_unlock(&dev->list_mutex);

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

static void w1_search_process(struct w1_master *dev, u8 search_type)
{
	w1_search_process_cb(dev, search_type, w1_slave_found);
}

/**
 * w1_process_callbacks() - execute each dev->async_list callback entry
 * @dev: w1_master device
 *
 * The w1 master list_mutex must be held.
 *
 * Return: 1 if there were commands to executed 0 otherwise
 */
int w1_process_callbacks(struct w1_master *dev)
{
	int ret = 0;
	struct w1_async_cmd *async_cmd, *async_n;

	/* The list can be added to in another thread, loop until it is empty */
	while (!list_empty(&dev->async_list)) {
		list_for_each_entry_safe(async_cmd, async_n, &dev->async_list,
			async_entry) {
			/* drop the lock, if it is a search it can take a long
			 * time */
			mutex_unlock(&dev->list_mutex);
			async_cmd->cb(dev, async_cmd);
			ret = 1;
			mutex_lock(&dev->list_mutex);
		}
	}
	return ret;
}

int w1_process(void *data)
{
	struct w1_master *dev = (struct w1_master *) data;
	/* As long as w1_timeout is only set by a module parameter the sleep
	 * time can be calculated in jiffies once.
	 */
	const unsigned long jtime =
	  usecs_to_jiffies(w1_timeout * 1000000 + w1_timeout_us);
	/* remainder if it woke up early */
	unsigned long jremain = 0;

	for (;;) {

		if (!jremain && dev->search_count) {
			mutex_lock(&dev->mutex);
			w1_search_process(dev, W1_SEARCH);
			mutex_unlock(&dev->mutex);
		}

		mutex_lock(&dev->list_mutex);
		/* Note, w1_process_callback drops the lock while processing,
		 * but locks it again before returning.
		 */
		if (!w1_process_callbacks(dev) && jremain) {
			/* a wake up is either to stop the thread, process
			 * callbacks, or search, it isn't process callbacks, so
			 * schedule a search.
			 */
			jremain = 1;
		}

		__set_current_state(TASK_INTERRUPTIBLE);

		/* hold list_mutex until after interruptible to prevent loosing
		 * the wakeup signal when async_cmd is added.
		 */
		mutex_unlock(&dev->list_mutex);

		if (kthread_should_stop())
			break;

		/* Only sleep when the search is active. */
		if (dev->search_count) {
			if (!jremain)
				jremain = jtime;
			jremain = schedule_timeout(jremain);
		}
		else
			schedule();
	}

	atomic_dec(&dev->refcnt);

	return 0;
}

static int __init w1_init(void)
{
	int retval;

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

	w1_init_netlink();

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

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

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

	return 0;

#if 0
/* For undoing the slave register if there was a step after it. */
err_out_slave_unregister:
	driver_unregister(&w1_slave_driver);
#endif

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 __exit w1_fini(void)
{
	struct w1_master *dev;

	/* Set netlink removal messages and some cleanup */
	list_for_each_entry(dev, &w1_masters, w1_master_entry)
		__w1_remove_master_device(dev);

	w1_fini_netlink();

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

module_init(w1_init);
module_exit(w1_fini);

MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
MODULE_LICENSE("GPL");