9b5c11701c374d50636eb23f975caac16a4b65b8
[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 #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         struct w1_master *md = dev_to_w1_master(dev);
250
251         mutex_lock(&md->mutex);
252         md->search_count = simple_strtol(buf, NULL, 0);
253         mutex_unlock(&md->mutex);
254         wake_up_process(md->thread);
255
256         return count;
257 }
258
259 static ssize_t w1_master_attribute_show_search(struct device *dev,
260                                                struct device_attribute *attr,
261                                                char *buf)
262 {
263         struct w1_master *md = dev_to_w1_master(dev);
264         ssize_t count;
265
266         mutex_lock(&md->mutex);
267         count = sprintf(buf, "%d\n", md->search_count);
268         mutex_unlock(&md->mutex);
269
270         return count;
271 }
272
273 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
274 {
275         struct w1_master *md = dev_to_w1_master(dev);
276         ssize_t count;
277
278         mutex_lock(&md->mutex);
279         count = sprintf(buf, "0x%p\n", md->bus_master);
280         mutex_unlock(&md->mutex);
281         return count;
282 }
283
284 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
285 {
286         ssize_t count;
287         count = sprintf(buf, "%d\n", w1_timeout);
288         return count;
289 }
290
291 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
292 {
293         struct w1_master *md = dev_to_w1_master(dev);
294         ssize_t count;
295
296         mutex_lock(&md->mutex);
297         count = sprintf(buf, "%d\n", md->max_slave_count);
298         mutex_unlock(&md->mutex);
299         return count;
300 }
301
302 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
303 {
304         struct w1_master *md = dev_to_w1_master(dev);
305         ssize_t count;
306
307         mutex_lock(&md->mutex);
308         count = sprintf(buf, "%lu\n", md->attempts);
309         mutex_unlock(&md->mutex);
310         return count;
311 }
312
313 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
314 {
315         struct w1_master *md = dev_to_w1_master(dev);
316         ssize_t count;
317
318         mutex_lock(&md->mutex);
319         count = sprintf(buf, "%d\n", md->slave_count);
320         mutex_unlock(&md->mutex);
321         return count;
322 }
323
324 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
325 {
326         struct w1_master *md = dev_to_w1_master(dev);
327         int c = PAGE_SIZE;
328
329         mutex_lock(&md->mutex);
330
331         if (md->slave_count == 0)
332                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
333         else {
334                 struct list_head *ent, *n;
335                 struct w1_slave *sl;
336
337                 list_for_each_safe(ent, n, &md->slist) {
338                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
339
340                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
341                 }
342         }
343
344         mutex_unlock(&md->mutex);
345
346         return PAGE_SIZE - c;
347 }
348
349 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
350         struct device_attribute w1_master_attribute_##_name =   \
351                 __ATTR(w1_master_##_name, _mode,                \
352                        w1_master_attribute_show_##_name, NULL)
353
354 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
355         struct device_attribute w1_master_attribute_##_name =   \
356                 __ATTR(w1_master_##_name, _mode,                \
357                        w1_master_attribute_show_##_name,        \
358                        w1_master_attribute_store_##_name)
359
360 static W1_MASTER_ATTR_RO(name, S_IRUGO);
361 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
362 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
363 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
364 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
365 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
366 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
367 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
368
369 static struct attribute *w1_master_default_attrs[] = {
370         &w1_master_attribute_name.attr,
371         &w1_master_attribute_slaves.attr,
372         &w1_master_attribute_slave_count.attr,
373         &w1_master_attribute_max_slave_count.attr,
374         &w1_master_attribute_attempts.attr,
375         &w1_master_attribute_timeout.attr,
376         &w1_master_attribute_pointer.attr,
377         &w1_master_attribute_search.attr,
378         NULL
379 };
380
381 static struct attribute_group w1_master_defattr_group = {
382         .attrs = w1_master_default_attrs,
383 };
384
385 int w1_create_master_attributes(struct w1_master *master)
386 {
387         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
388 }
389
390 void w1_destroy_master_attributes(struct w1_master *master)
391 {
392         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
393 }
394
395 #ifdef CONFIG_HOTPLUG
396 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
397 {
398         struct w1_master *md = NULL;
399         struct w1_slave *sl = NULL;
400         char *event_owner, *name;
401         int err;
402
403         if (dev->driver == &w1_master_driver) {
404                 md = container_of(dev, struct w1_master, dev);
405                 event_owner = "master";
406                 name = md->name;
407         } else if (dev->driver == &w1_slave_driver) {
408                 sl = container_of(dev, struct w1_slave, dev);
409                 event_owner = "slave";
410                 name = sl->name;
411         } else {
412                 dev_dbg(dev, "Unknown event.\n");
413                 return -EINVAL;
414         }
415
416         dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
417                         event_owner, name, dev->bus_id);
418
419         if (dev->driver != &w1_slave_driver || !sl)
420                 return 0;
421
422         err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
423         if (err)
424                 return err;
425
426         err = add_uevent_var(env, "W1_SLAVE_ID=%024LX",
427                              (unsigned long long)sl->reg_num.id);
428         if (err)
429                 return err;
430
431         return 0;
432 };
433 #else
434 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
435 {
436         return 0;
437 }
438 #endif
439
440 static int __w1_attach_slave_device(struct w1_slave *sl)
441 {
442         int err;
443
444         sl->dev.parent = &sl->master->dev;
445         sl->dev.driver = &w1_slave_driver;
446         sl->dev.bus = &w1_bus_type;
447         sl->dev.release = &w1_slave_release;
448
449         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
450                  "%02x-%012llx",
451                  (unsigned int) sl->reg_num.family,
452                  (unsigned long long) sl->reg_num.id);
453         snprintf(&sl->name[0], sizeof(sl->name),
454                  "%02x-%012llx",
455                  (unsigned int) sl->reg_num.family,
456                  (unsigned long long) sl->reg_num.id);
457
458         dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
459                 &sl->dev.bus_id[0], sl);
460
461         err = device_register(&sl->dev);
462         if (err < 0) {
463                 dev_err(&sl->dev,
464                         "Device registration [%s] failed. err=%d\n",
465                         sl->dev.bus_id, err);
466                 return err;
467         }
468
469         /* Create "name" entry */
470         err = device_create_file(&sl->dev, &w1_slave_attr_name);
471         if (err < 0) {
472                 dev_err(&sl->dev,
473                         "sysfs file creation for [%s] failed. err=%d\n",
474                         sl->dev.bus_id, err);
475                 goto out_unreg;
476         }
477
478         /* Create "id" entry */
479         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
480         if (err < 0) {
481                 dev_err(&sl->dev,
482                         "sysfs file creation for [%s] failed. err=%d\n",
483                         sl->dev.bus_id, err);
484                 goto out_rem1;
485         }
486
487         /* if the family driver needs to initialize something... */
488         if (sl->family->fops && sl->family->fops->add_slave &&
489             ((err = sl->family->fops->add_slave(sl)) < 0)) {
490                 dev_err(&sl->dev,
491                         "sysfs file creation for [%s] failed. err=%d\n",
492                         sl->dev.bus_id, err);
493                 goto out_rem2;
494         }
495
496         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
497
498         return 0;
499
500 out_rem2:
501         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
502 out_rem1:
503         device_remove_file(&sl->dev, &w1_slave_attr_name);
504 out_unreg:
505         device_unregister(&sl->dev);
506         return err;
507 }
508
509 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
510 {
511         struct w1_slave *sl;
512         struct w1_family *f;
513         int err;
514         struct w1_netlink_msg msg;
515
516         sl = kzalloc(sizeof(struct w1_slave), GFP_KERNEL);
517         if (!sl) {
518                 dev_err(&dev->dev,
519                          "%s: failed to allocate new slave device.\n",
520                          __func__);
521                 return -ENOMEM;
522         }
523
524
525         sl->owner = THIS_MODULE;
526         sl->master = dev;
527         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
528
529         memset(&msg, 0, sizeof(msg));
530         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
531         atomic_set(&sl->refcnt, 0);
532         init_completion(&sl->released);
533
534         spin_lock(&w1_flock);
535         f = w1_family_registered(rn->family);
536         if (!f) {
537                 f= &w1_default_family;
538                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
539                           rn->family, rn->family,
540                           (unsigned long long)rn->id, rn->crc);
541         }
542         __w1_family_get(f);
543         spin_unlock(&w1_flock);
544
545         sl->family = f;
546
547
548         err = __w1_attach_slave_device(sl);
549         if (err < 0) {
550                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
551                          sl->name);
552                 w1_family_put(sl->family);
553                 kfree(sl);
554                 return err;
555         }
556
557         sl->ttl = dev->slave_ttl;
558         dev->slave_count++;
559
560         memcpy(msg.id.id, rn, sizeof(msg.id));
561         msg.type = W1_SLAVE_ADD;
562         w1_netlink_send(dev, &msg);
563
564         return 0;
565 }
566
567 void w1_slave_detach(struct w1_slave *sl)
568 {
569         struct w1_netlink_msg msg;
570
571         dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
572
573         list_del(&sl->w1_slave_entry);
574
575         if (sl->family->fops && sl->family->fops->remove_slave)
576                 sl->family->fops->remove_slave(sl);
577
578         memset(&msg, 0, sizeof(msg));
579         memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
580         msg.type = W1_SLAVE_REMOVE;
581         w1_netlink_send(sl->master, &msg);
582
583         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
584         device_remove_file(&sl->dev, &w1_slave_attr_name);
585         device_unregister(&sl->dev);
586
587         wait_for_completion(&sl->released);
588         kfree(sl);
589 }
590
591 struct w1_master *w1_search_master_id(u32 id)
592 {
593         struct w1_master *dev;
594         int found = 0;
595
596         mutex_lock(&w1_mlock);
597         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
598                 if (dev->id == id) {
599                         found = 1;
600                         atomic_inc(&dev->refcnt);
601                         break;
602                 }
603         }
604         mutex_unlock(&w1_mlock);
605
606         return (found)?dev:NULL;
607 }
608
609 struct w1_slave *w1_search_slave(struct w1_reg_num *id)
610 {
611         struct w1_master *dev;
612         struct w1_slave *sl = NULL;
613         int found = 0;
614
615         mutex_lock(&w1_mlock);
616         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
617                 mutex_lock(&dev->mutex);
618                 list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
619                         if (sl->reg_num.family == id->family &&
620                                         sl->reg_num.id == id->id &&
621                                         sl->reg_num.crc == id->crc) {
622                                 found = 1;
623                                 atomic_inc(&dev->refcnt);
624                                 atomic_inc(&sl->refcnt);
625                                 break;
626                         }
627                 }
628                 mutex_unlock(&dev->mutex);
629
630                 if (found)
631                         break;
632         }
633         mutex_unlock(&w1_mlock);
634
635         return (found)?sl:NULL;
636 }
637
638 void w1_reconnect_slaves(struct w1_family *f, int attach)
639 {
640         struct w1_slave *sl, *sln;
641         struct w1_master *dev;
642
643         mutex_lock(&w1_mlock);
644         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
645                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
646                         "for family %02x.\n", dev->name, f->fid);
647                 mutex_lock(&dev->mutex);
648                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
649                         /* If it is a new family, slaves with the default
650                          * family driver and are that family will be
651                          * connected.  If the family is going away, devices
652                          * matching that family are reconneced.
653                          */
654                         if ((attach && sl->family->fid == W1_FAMILY_DEFAULT
655                                 && sl->reg_num.family == f->fid) ||
656                                 (!attach && sl->family->fid == f->fid)) {
657                                 struct w1_reg_num rn;
658
659                                 memcpy(&rn, &sl->reg_num, sizeof(rn));
660                                 w1_slave_detach(sl);
661
662                                 w1_attach_slave_device(dev, &rn);
663                         }
664                 }
665                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
666                         "has been finished.\n", dev->name);
667                 mutex_unlock(&dev->mutex);
668         }
669         mutex_unlock(&w1_mlock);
670 }
671
672 static void w1_slave_found(struct w1_master *dev, u64 rn)
673 {
674         int slave_count;
675         struct w1_slave *sl;
676         struct list_head *ent;
677         struct w1_reg_num *tmp;
678         u64 rn_le = cpu_to_le64(rn);
679
680         atomic_inc(&dev->refcnt);
681
682         tmp = (struct w1_reg_num *) &rn;
683
684         slave_count = 0;
685         list_for_each(ent, &dev->slist) {
686
687                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
688
689                 if (sl->reg_num.family == tmp->family &&
690                     sl->reg_num.id == tmp->id &&
691                     sl->reg_num.crc == tmp->crc) {
692                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
693                         break;
694                 }
695
696                 slave_count++;
697         }
698
699         if (slave_count == dev->slave_count &&
700                 rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
701                 w1_attach_slave_device(dev, tmp);
702         }
703
704         atomic_dec(&dev->refcnt);
705 }
706
707 /**
708  * Performs a ROM Search & registers any devices found.
709  * The 1-wire search is a simple binary tree search.
710  * For each bit of the address, we read two bits and write one bit.
711  * The bit written will put to sleep all devies that don't match that bit.
712  * When the two reads differ, the direction choice is obvious.
713  * When both bits are 0, we must choose a path to take.
714  * When we can scan all 64 bits without having to choose a path, we are done.
715  *
716  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
717  *
718  * @dev        The master device to search
719  * @cb         Function to call when a device is found
720  */
721 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
722 {
723         u64 last_rn, rn, tmp64;
724         int i, slave_count = 0;
725         int last_zero, last_device;
726         int search_bit, desc_bit;
727         u8  triplet_ret = 0;
728
729         search_bit = 0;
730         rn = last_rn = 0;
731         last_device = 0;
732         last_zero = -1;
733
734         desc_bit = 64;
735
736         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
737                 last_rn = rn;
738                 rn = 0;
739
740                 /*
741                  * Reset bus and all 1-wire device state machines
742                  * so they can respond to our requests.
743                  *
744                  * Return 0 - device(s) present, 1 - no devices present.
745                  */
746                 if (w1_reset_bus(dev)) {
747                         dev_dbg(&dev->dev, "No devices present on the wire.\n");
748                         break;
749                 }
750
751                 /* Start the search */
752                 w1_write_8(dev, search_type);
753                 for (i = 0; i < 64; ++i) {
754                         /* Determine the direction/search bit */
755                         if (i == desc_bit)
756                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
757                         else if (i > desc_bit)
758                                 search_bit = 0;   /* take the 0 path on the next branch */
759                         else
760                                 search_bit = ((last_rn >> i) & 0x1);
761
762                         /** Read two bits and write one bit */
763                         triplet_ret = w1_triplet(dev, search_bit);
764
765                         /* quit if no device responded */
766                         if ( (triplet_ret & 0x03) == 0x03 )
767                                 break;
768
769                         /* If both directions were valid, and we took the 0 path... */
770                         if (triplet_ret == 0)
771                                 last_zero = i;
772
773                         /* extract the direction taken & update the device number */
774                         tmp64 = (triplet_ret >> 2);
775                         rn |= (tmp64 << i);
776
777                         if (kthread_should_stop()) {
778                                 printk(KERN_INFO "Abort w1_search (exiting)\n");
779                                 return;
780                         }
781                 }
782
783                 if ( (triplet_ret & 0x03) != 0x03 ) {
784                         if ( (desc_bit == last_zero) || (last_zero < 0))
785                                 last_device = 1;
786                         desc_bit = last_zero;
787                         cb(dev, rn);
788                 }
789         }
790 }
791
792 void w1_search_process(struct w1_master *dev, u8 search_type)
793 {
794         struct w1_slave *sl, *sln;
795
796         list_for_each_entry(sl, &dev->slist, w1_slave_entry)
797                 clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
798
799         w1_search_devices(dev, search_type, w1_slave_found);
800
801         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
802                 if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl)
803                         w1_slave_detach(sl);
804                 else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
805                         sl->ttl = dev->slave_ttl;
806         }
807
808         if (dev->search_count > 0)
809                 dev->search_count--;
810 }
811
812 int w1_process(void *data)
813 {
814         struct w1_master *dev = (struct w1_master *) data;
815         /* As long as w1_timeout is only set by a module parameter the sleep
816          * time can be calculated in jiffies once.
817          */
818         const unsigned long jtime = msecs_to_jiffies(w1_timeout * 1000);
819
820         while (!kthread_should_stop()) {
821                 if (dev->search_count) {
822                         mutex_lock(&dev->mutex);
823                         w1_search_process(dev, W1_SEARCH);
824                         mutex_unlock(&dev->mutex);
825                 }
826
827                 try_to_freeze();
828                 __set_current_state(TASK_INTERRUPTIBLE);
829
830                 if (kthread_should_stop())
831                         break;
832
833                 /* Only sleep when the search is active. */
834                 if (dev->search_count)
835                         schedule_timeout(jtime);
836                 else
837                         schedule();
838         }
839
840         atomic_dec(&dev->refcnt);
841
842         return 0;
843 }
844
845 static int w1_init(void)
846 {
847         int retval;
848
849         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
850
851         w1_init_netlink();
852
853         retval = bus_register(&w1_bus_type);
854         if (retval) {
855                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
856                 goto err_out_exit_init;
857         }
858
859         retval = driver_register(&w1_master_driver);
860         if (retval) {
861                 printk(KERN_ERR
862                         "Failed to register master driver. err=%d.\n",
863                         retval);
864                 goto err_out_bus_unregister;
865         }
866
867         retval = driver_register(&w1_slave_driver);
868         if (retval) {
869                 printk(KERN_ERR
870                         "Failed to register master driver. err=%d.\n",
871                         retval);
872                 goto err_out_master_unregister;
873         }
874
875         return 0;
876
877 #if 0
878 /* For undoing the slave register if there was a step after it. */
879 err_out_slave_unregister:
880         driver_unregister(&w1_slave_driver);
881 #endif
882
883 err_out_master_unregister:
884         driver_unregister(&w1_master_driver);
885
886 err_out_bus_unregister:
887         bus_unregister(&w1_bus_type);
888
889 err_out_exit_init:
890         return retval;
891 }
892
893 static void w1_fini(void)
894 {
895         struct w1_master *dev;
896
897         /* Set netlink removal messages and some cleanup */
898         list_for_each_entry(dev, &w1_masters, w1_master_entry)
899                 __w1_remove_master_device(dev);
900
901         w1_fini_netlink();
902
903         driver_unregister(&w1_slave_driver);
904         driver_unregister(&w1_master_driver);
905         bus_unregister(&w1_bus_type);
906 }
907
908 module_init(w1_init);
909 module_exit(w1_fini);