[PATCH] w1: warning fix
[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
35 #include <asm/atomic.h>
36
37 #include "w1.h"
38 #include "w1_log.h"
39 #include "w1_int.h"
40 #include "w1_family.h"
41 #include "w1_netlink.h"
42
43 MODULE_LICENSE("GPL");
44 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
45 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
46
47 static int w1_timeout = 10;
48 static int w1_control_timeout = 1;
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(control_timeout, w1_control_timeout, int, 0);
54 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
55 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
56
57 DEFINE_MUTEX(w1_mlock);
58 LIST_HEAD(w1_masters);
59
60 static struct task_struct *w1_control_thread;
61
62 static int w1_master_match(struct device *dev, struct device_driver *drv)
63 {
64         return 1;
65 }
66
67 static int w1_master_probe(struct device *dev)
68 {
69         return -ENODEV;
70 }
71
72 static void w1_master_release(struct device *dev)
73 {
74         struct w1_master *md = dev_to_w1_master(dev);
75
76         dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
77         memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
78         kfree(md);
79 }
80
81 static void w1_slave_release(struct device *dev)
82 {
83         struct w1_slave *sl = dev_to_w1_slave(dev);
84
85         printk("%s: Releasing %s.\n", __func__, sl->name);
86
87         while (atomic_read(&sl->refcnt)) {
88                 printk("Waiting for %s to become free: refcnt=%d.\n",
89                                 sl->name, atomic_read(&sl->refcnt));
90                 if (msleep_interruptible(1000))
91                         flush_signals(current);
92         }
93
94         w1_family_put(sl->family);
95         sl->master->slave_count--;
96
97         complete(&sl->released);
98 }
99
100 static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
101 {
102         struct w1_slave *sl = dev_to_w1_slave(dev);
103
104         return sprintf(buf, "%s\n", sl->name);
105 }
106
107 static ssize_t w1_slave_read_id(struct kobject *kobj, char *buf, loff_t off, size_t count)
108 {
109         struct w1_slave *sl = kobj_to_w1_slave(kobj);
110
111         if (off > 8) {
112                 count = 0;
113         } else {
114                 if (off + count > 8)
115                         count = 8 - off;
116
117                 memcpy(buf, (u8 *)&sl->reg_num, count);
118         }
119
120         return count;
121 }
122
123 static struct device_attribute w1_slave_attr_name =
124         __ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
125
126 static struct bin_attribute w1_slave_attr_bin_id = {
127       .attr = {
128               .name = "id",
129               .mode = S_IRUGO,
130               .owner = THIS_MODULE,
131       },
132       .size = 8,
133       .read = w1_slave_read_id,
134 };
135
136 /* Default family */
137
138 static ssize_t w1_default_write(struct kobject *kobj, 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, char *buf, loff_t off, size_t count)
156 {
157         struct w1_slave *sl = kobj_to_w1_slave(kobj);
158
159         mutex_lock(&sl->master->mutex);
160         w1_read_block(sl->master, buf, count);
161         mutex_unlock(&sl->master->mutex);
162         return count;
163 }
164
165 static struct bin_attribute w1_default_attr = {
166       .attr = {
167               .name = "rw",
168               .mode = S_IRUGO | S_IWUSR,
169               .owner = THIS_MODULE,
170       },
171       .size = PAGE_SIZE,
172       .read = w1_default_read,
173       .write = w1_default_write,
174 };
175
176 static int w1_default_add_slave(struct w1_slave *sl)
177 {
178         return sysfs_create_bin_file(&sl->dev.kobj, &w1_default_attr);
179 }
180
181 static void w1_default_remove_slave(struct w1_slave *sl)
182 {
183         sysfs_remove_bin_file(&sl->dev.kobj, &w1_default_attr);
184 }
185
186 static struct w1_family_ops w1_default_fops = {
187         .add_slave      = w1_default_add_slave,
188         .remove_slave   = w1_default_remove_slave,
189 };
190
191 static struct w1_family w1_default_family = {
192         .fops = &w1_default_fops,
193 };
194
195 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size);
196
197 static struct bus_type w1_bus_type = {
198         .name = "w1",
199         .match = w1_master_match,
200         .uevent = w1_uevent,
201 };
202
203 struct device_driver w1_master_driver = {
204         .name = "w1_master_driver",
205         .bus = &w1_bus_type,
206         .probe = w1_master_probe,
207 };
208
209 struct device w1_master_device = {
210         .parent = NULL,
211         .bus = &w1_bus_type,
212         .bus_id = "w1 bus master",
213         .driver = &w1_master_driver,
214         .release = &w1_master_release
215 };
216
217 static struct device_driver w1_slave_driver = {
218         .name = "w1_slave_driver",
219         .bus = &w1_bus_type,
220 };
221
222 #if 0
223 struct device w1_slave_device = {
224         .parent = NULL,
225         .bus = &w1_bus_type,
226         .bus_id = "w1 bus slave",
227         .driver = &w1_slave_driver,
228         .release = &w1_slave_release
229 };
230 #endif  /*  0  */
231
232 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
233 {
234         struct w1_master *md = dev_to_w1_master(dev);
235         ssize_t count;
236
237         mutex_lock(&md->mutex);
238         count = sprintf(buf, "%s\n", md->name);
239         mutex_unlock(&md->mutex);
240
241         return count;
242 }
243
244 static ssize_t w1_master_attribute_store_search(struct device * dev,
245                                                 struct device_attribute *attr,
246                                                 const char * buf, size_t count)
247 {
248         struct w1_master *md = dev_to_w1_master(dev);
249
250         mutex_lock(&md->mutex);
251         md->search_count = simple_strtol(buf, NULL, 0);
252         mutex_unlock(&md->mutex);
253
254         return count;
255 }
256
257 static ssize_t w1_master_attribute_show_search(struct device *dev,
258                                                struct device_attribute *attr,
259                                                char *buf)
260 {
261         struct w1_master *md = dev_to_w1_master(dev);
262         ssize_t count;
263
264         mutex_lock(&md->mutex);
265         count = sprintf(buf, "%d\n", md->search_count);
266         mutex_unlock(&md->mutex);
267
268         return count;
269 }
270
271 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
272 {
273         struct w1_master *md = dev_to_w1_master(dev);
274         ssize_t count;
275
276         mutex_lock(&md->mutex);
277         count = sprintf(buf, "0x%p\n", md->bus_master);
278         mutex_unlock(&md->mutex);
279         return count;
280 }
281
282 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
283 {
284         ssize_t count;
285         count = sprintf(buf, "%d\n", w1_timeout);
286         return count;
287 }
288
289 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
290 {
291         struct w1_master *md = dev_to_w1_master(dev);
292         ssize_t count;
293
294         mutex_lock(&md->mutex);
295         count = sprintf(buf, "%d\n", md->max_slave_count);
296         mutex_unlock(&md->mutex);
297         return count;
298 }
299
300 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
301 {
302         struct w1_master *md = dev_to_w1_master(dev);
303         ssize_t count;
304
305         mutex_lock(&md->mutex);
306         count = sprintf(buf, "%lu\n", md->attempts);
307         mutex_unlock(&md->mutex);
308         return count;
309 }
310
311 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
312 {
313         struct w1_master *md = dev_to_w1_master(dev);
314         ssize_t count;
315
316         mutex_lock(&md->mutex);
317         count = sprintf(buf, "%d\n", md->slave_count);
318         mutex_unlock(&md->mutex);
319         return count;
320 }
321
322 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
323 {
324         struct w1_master *md = dev_to_w1_master(dev);
325         int c = PAGE_SIZE;
326
327         mutex_lock(&md->mutex);
328
329         if (md->slave_count == 0)
330                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
331         else {
332                 struct list_head *ent, *n;
333                 struct w1_slave *sl;
334
335                 list_for_each_safe(ent, n, &md->slist) {
336                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
337
338                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
339                 }
340         }
341
342         mutex_unlock(&md->mutex);
343
344         return PAGE_SIZE - c;
345 }
346
347 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
348         struct device_attribute w1_master_attribute_##_name =   \
349                 __ATTR(w1_master_##_name, _mode,                \
350                        w1_master_attribute_show_##_name, NULL)
351
352 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
353         struct device_attribute w1_master_attribute_##_name =   \
354                 __ATTR(w1_master_##_name, _mode,                \
355                        w1_master_attribute_show_##_name,        \
356                        w1_master_attribute_store_##_name)
357
358 static W1_MASTER_ATTR_RO(name, S_IRUGO);
359 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
360 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
361 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
362 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
363 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
364 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
365 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
366
367 static struct attribute *w1_master_default_attrs[] = {
368         &w1_master_attribute_name.attr,
369         &w1_master_attribute_slaves.attr,
370         &w1_master_attribute_slave_count.attr,
371         &w1_master_attribute_max_slave_count.attr,
372         &w1_master_attribute_attempts.attr,
373         &w1_master_attribute_timeout.attr,
374         &w1_master_attribute_pointer.attr,
375         &w1_master_attribute_search.attr,
376         NULL
377 };
378
379 static struct attribute_group w1_master_defattr_group = {
380         .attrs = w1_master_default_attrs,
381 };
382
383 int w1_create_master_attributes(struct w1_master *master)
384 {
385         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
386 }
387
388 static void w1_destroy_master_attributes(struct w1_master *master)
389 {
390         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
391 }
392
393 #ifdef CONFIG_HOTPLUG
394 static int w1_uevent(struct device *dev, char **envp, int num_envp,
395                         char *buffer, int buffer_size)
396 {
397         struct w1_master *md = NULL;
398         struct w1_slave *sl = NULL;
399         char *event_owner, *name;
400         int err, cur_index=0, cur_len=0;
401
402         if (dev->driver == &w1_master_driver) {
403                 md = container_of(dev, struct w1_master, dev);
404                 event_owner = "master";
405                 name = md->name;
406         } else if (dev->driver == &w1_slave_driver) {
407                 sl = container_of(dev, struct w1_slave, dev);
408                 event_owner = "slave";
409                 name = sl->name;
410         } else {
411                 dev_dbg(dev, "Unknown event.\n");
412                 return -EINVAL;
413         }
414
415         dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
416                         event_owner, name, dev->bus_id);
417
418         if (dev->driver != &w1_slave_driver || !sl)
419                 return 0;
420
421         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
422                         &cur_len, "W1_FID=%02X", sl->reg_num.family);
423         if (err)
424                 return err;
425
426         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
427                         &cur_len, "W1_SLAVE_ID=%024LX",
428                         (unsigned long long)sl->reg_num.id);
429         if (err)
430                 return err;
431
432         return 0;
433 };
434 #else
435 static int w1_uevent(struct device *dev, char **envp, int num_envp,
436                         char *buffer, int buffer_size)
437 {
438         return 0;
439 }
440 #endif
441
442 static int __w1_attach_slave_device(struct w1_slave *sl)
443 {
444         int err;
445
446         sl->dev.parent = &sl->master->dev;
447         sl->dev.driver = &w1_slave_driver;
448         sl->dev.bus = &w1_bus_type;
449         sl->dev.release = &w1_slave_release;
450
451         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
452                  "%02x-%012llx",
453                  (unsigned int) sl->reg_num.family,
454                  (unsigned long long) sl->reg_num.id);
455         snprintf(&sl->name[0], sizeof(sl->name),
456                  "%02x-%012llx",
457                  (unsigned int) sl->reg_num.family,
458                  (unsigned long long) sl->reg_num.id);
459
460         dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
461                 &sl->dev.bus_id[0]);
462
463         err = device_register(&sl->dev);
464         if (err < 0) {
465                 dev_err(&sl->dev,
466                         "Device registration [%s] failed. err=%d\n",
467                         sl->dev.bus_id, err);
468                 return err;
469         }
470
471         /* Create "name" entry */
472         err = device_create_file(&sl->dev, &w1_slave_attr_name);
473         if (err < 0) {
474                 dev_err(&sl->dev,
475                         "sysfs file creation for [%s] failed. err=%d\n",
476                         sl->dev.bus_id, err);
477                 goto out_unreg;
478         }
479
480         /* Create "id" entry */
481         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
482         if (err < 0) {
483                 dev_err(&sl->dev,
484                         "sysfs file creation for [%s] failed. err=%d\n",
485                         sl->dev.bus_id, err);
486                 goto out_rem1;
487         }
488
489         /* if the family driver needs to initialize something... */
490         if (sl->family->fops && sl->family->fops->add_slave &&
491             ((err = sl->family->fops->add_slave(sl)) < 0)) {
492                 dev_err(&sl->dev,
493                         "sysfs file creation for [%s] failed. err=%d\n",
494                         sl->dev.bus_id, err);
495                 goto out_rem2;
496         }
497
498         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
499
500         return 0;
501
502 out_rem2:
503         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
504 out_rem1:
505         device_remove_file(&sl->dev, &w1_slave_attr_name);
506 out_unreg:
507         device_unregister(&sl->dev);
508         return err;
509 }
510
511 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
512 {
513         struct w1_slave *sl;
514         struct w1_family *f;
515         int err;
516         struct w1_netlink_msg msg;
517
518         sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
519         if (!sl) {
520                 dev_err(&dev->dev,
521                          "%s: failed to allocate new slave device.\n",
522                          __func__);
523                 return -ENOMEM;
524         }
525
526         memset(sl, 0, sizeof(*sl));
527
528         sl->owner = THIS_MODULE;
529         sl->master = dev;
530         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
531
532         memset(&msg, 0, sizeof(msg));
533         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
534         atomic_set(&sl->refcnt, 0);
535         init_completion(&sl->released);
536
537         spin_lock(&w1_flock);
538         f = w1_family_registered(rn->family);
539         if (!f) {
540                 f= &w1_default_family;
541                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
542                           rn->family, rn->family,
543                           (unsigned long long)rn->id, rn->crc);
544         }
545         __w1_family_get(f);
546         spin_unlock(&w1_flock);
547
548         sl->family = f;
549
550
551         err = __w1_attach_slave_device(sl);
552         if (err < 0) {
553                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
554                          sl->name);
555                 w1_family_put(sl->family);
556                 kfree(sl);
557                 return err;
558         }
559
560         sl->ttl = dev->slave_ttl;
561         dev->slave_count++;
562
563         memcpy(msg.id.id, rn, sizeof(msg.id));
564         msg.type = W1_SLAVE_ADD;
565         w1_netlink_send(dev, &msg);
566
567         return 0;
568 }
569
570 static void w1_slave_detach(struct w1_slave *sl)
571 {
572         struct w1_netlink_msg msg;
573
574         dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
575
576         list_del(&sl->w1_slave_entry);
577
578         if (sl->family->fops && sl->family->fops->remove_slave)
579                 sl->family->fops->remove_slave(sl);
580
581         memset(&msg, 0, sizeof(msg));
582         memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
583         msg.type = W1_SLAVE_REMOVE;
584         w1_netlink_send(sl->master, &msg);
585
586         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
587         device_remove_file(&sl->dev, &w1_slave_attr_name);
588         device_unregister(&sl->dev);
589
590         wait_for_completion(&sl->released);
591         kfree(sl);
592 }
593
594 static struct w1_master *w1_search_master(void *data)
595 {
596         struct w1_master *dev;
597         int found = 0;
598
599         mutex_lock(&w1_mlock);
600         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
601                 if (dev->bus_master->data == data) {
602                         found = 1;
603                         atomic_inc(&dev->refcnt);
604                         break;
605                 }
606         }
607         mutex_unlock(&w1_mlock);
608
609         return (found)?dev:NULL;
610 }
611
612 struct w1_master *w1_search_master_id(u32 id)
613 {
614         struct w1_master *dev;
615         int found = 0;
616
617         mutex_lock(&w1_mlock);
618         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
619                 if (dev->id == id) {
620                         found = 1;
621                         atomic_inc(&dev->refcnt);
622                         break;
623                 }
624         }
625         mutex_unlock(&w1_mlock);
626
627         return (found)?dev:NULL;
628 }
629
630 struct w1_slave *w1_search_slave(struct w1_reg_num *id)
631 {
632         struct w1_master *dev;
633         struct w1_slave *sl = NULL;
634         int found = 0;
635
636         mutex_lock(&w1_mlock);
637         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
638                 mutex_lock(&dev->mutex);
639                 list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
640                         if (sl->reg_num.family == id->family &&
641                                         sl->reg_num.id == id->id &&
642                                         sl->reg_num.crc == id->crc) {
643                                 found = 1;
644                                 atomic_inc(&dev->refcnt);
645                                 atomic_inc(&sl->refcnt);
646                                 break;
647                         }
648                 }
649                 mutex_unlock(&dev->mutex);
650
651                 if (found)
652                         break;
653         }
654         mutex_unlock(&w1_mlock);
655
656         return (found)?sl:NULL;
657 }
658
659 void w1_reconnect_slaves(struct w1_family *f)
660 {
661         struct w1_master *dev;
662
663         mutex_lock(&w1_mlock);
664         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
665                 dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
666                                 dev->name, f->fid);
667                 set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
668         }
669         mutex_unlock(&w1_mlock);
670 }
671
672 static void w1_slave_found(void *data, u64 rn)
673 {
674         int slave_count;
675         struct w1_slave *sl;
676         struct list_head *ent;
677         struct w1_reg_num *tmp;
678         int family_found = 0;
679         struct w1_master *dev;
680         u64 rn_le = cpu_to_le64(rn);
681
682         dev = w1_search_master(data);
683         if (!dev) {
684                 printk(KERN_ERR "Failed to find w1 master device for data %p, "
685                        "it is impossible.\n", data);
686                 return;
687         }
688
689         tmp = (struct w1_reg_num *) &rn;
690
691         slave_count = 0;
692         list_for_each(ent, &dev->slist) {
693
694                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
695
696                 if (sl->reg_num.family == tmp->family &&
697                     sl->reg_num.id == tmp->id &&
698                     sl->reg_num.crc == tmp->crc) {
699                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
700                         break;
701                 } else if (sl->reg_num.family == tmp->family) {
702                         family_found = 1;
703                         break;
704                 }
705
706                 slave_count++;
707         }
708
709         if (slave_count == dev->slave_count &&
710                 rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
711                 w1_attach_slave_device(dev, tmp);
712         }
713
714         atomic_dec(&dev->refcnt);
715 }
716
717 /**
718  * Performs a ROM Search & registers any devices found.
719  * The 1-wire search is a simple binary tree search.
720  * For each bit of the address, we read two bits and write one bit.
721  * The bit written will put to sleep all devies that don't match that bit.
722  * When the two reads differ, the direction choice is obvious.
723  * When both bits are 0, we must choose a path to take.
724  * When we can scan all 64 bits without having to choose a path, we are done.
725  *
726  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
727  *
728  * @dev        The master device to search
729  * @cb         Function to call when a device is found
730  */
731 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
732 {
733         u64 last_rn, rn, tmp64;
734         int i, slave_count = 0;
735         int last_zero, last_device;
736         int search_bit, desc_bit;
737         u8  triplet_ret = 0;
738
739         search_bit = 0;
740         rn = last_rn = 0;
741         last_device = 0;
742         last_zero = -1;
743
744         desc_bit = 64;
745
746         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
747                 last_rn = rn;
748                 rn = 0;
749
750                 /*
751                  * Reset bus and all 1-wire device state machines
752                  * so they can respond to our requests.
753                  *
754                  * Return 0 - device(s) present, 1 - no devices present.
755                  */
756                 if (w1_reset_bus(dev)) {
757                         dev_dbg(&dev->dev, "No devices present on the wire.\n");
758                         break;
759                 }
760
761                 /* Start the search */
762                 w1_write_8(dev, search_type);
763                 for (i = 0; i < 64; ++i) {
764                         /* Determine the direction/search bit */
765                         if (i == desc_bit)
766                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
767                         else if (i > desc_bit)
768                                 search_bit = 0;   /* take the 0 path on the next branch */
769                         else
770                                 search_bit = ((last_rn >> i) & 0x1);
771
772                         /** Read two bits and write one bit */
773                         triplet_ret = w1_triplet(dev, search_bit);
774
775                         /* quit if no device responded */
776                         if ( (triplet_ret & 0x03) == 0x03 )
777                                 break;
778
779                         /* If both directions were valid, and we took the 0 path... */
780                         if (triplet_ret == 0)
781                                 last_zero = i;
782
783                         /* extract the direction taken & update the device number */
784                         tmp64 = (triplet_ret >> 2);
785                         rn |= (tmp64 << i);
786                 }
787
788                 if ( (triplet_ret & 0x03) != 0x03 ) {
789                         if ( (desc_bit == last_zero) || (last_zero < 0))
790                                 last_device = 1;
791                         desc_bit = last_zero;
792                         cb(dev->bus_master->data, rn);
793                 }
794         }
795 }
796
797 static int w1_control(void *data)
798 {
799         struct w1_slave *sl, *sln;
800         struct w1_master *dev, *n;
801         int have_to_wait = 0;
802
803         while (!kthread_should_stop() || have_to_wait) {
804                 have_to_wait = 0;
805
806                 try_to_freeze();
807                 msleep_interruptible(w1_control_timeout * 1000);
808
809                 list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
810                         if (!kthread_should_stop() && !dev->flags)
811                                 continue;
812                         /*
813                          * Little race: we can create thread but not set the flag.
814                          * Get a chance for external process to set flag up.
815                          */
816                         if (!dev->initialized) {
817                                 have_to_wait = 1;
818                                 continue;
819                         }
820
821                         if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
822                                 set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
823
824                                 mutex_lock(&w1_mlock);
825                                 list_del(&dev->w1_master_entry);
826                                 mutex_unlock(&w1_mlock);
827
828                                 mutex_lock(&dev->mutex);
829                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
830                                         w1_slave_detach(sl);
831                                 }
832                                 w1_destroy_master_attributes(dev);
833                                 mutex_unlock(&dev->mutex);
834                                 atomic_dec(&dev->refcnt);
835                                 continue;
836                         }
837
838                         if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
839                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
840                                 mutex_lock(&dev->mutex);
841                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
842                                         if (sl->family->fid == W1_FAMILY_DEFAULT) {
843                                                 struct w1_reg_num rn;
844
845                                                 memcpy(&rn, &sl->reg_num, sizeof(rn));
846                                                 w1_slave_detach(sl);
847
848                                                 w1_attach_slave_device(dev, &rn);
849                                         }
850                                 }
851                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
852                                 clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
853                                 mutex_unlock(&dev->mutex);
854                         }
855                 }
856         }
857
858         return 0;
859 }
860
861 void w1_search_process(struct w1_master *dev, u8 search_type)
862 {
863         struct w1_slave *sl, *sln;
864
865         list_for_each_entry(sl, &dev->slist, w1_slave_entry)
866                 clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
867
868         w1_search_devices(dev, search_type, w1_slave_found);
869
870         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
871                 if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
872                         w1_slave_detach(sl);
873
874                         dev->slave_count--;
875                 } else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
876                         sl->ttl = dev->slave_ttl;
877         }
878
879         if (dev->search_count > 0)
880                 dev->search_count--;
881 }
882
883 int w1_process(void *data)
884 {
885         struct w1_master *dev = (struct w1_master *) data;
886
887         while (!kthread_should_stop() && !test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
888                 try_to_freeze();
889                 msleep_interruptible(w1_timeout * 1000);
890
891                 if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
892                         break;
893
894                 if (!dev->initialized)
895                         continue;
896
897                 if (dev->search_count == 0)
898                         continue;
899
900                 mutex_lock(&dev->mutex);
901                 w1_search_process(dev, W1_SEARCH);
902                 mutex_unlock(&dev->mutex);
903         }
904
905         atomic_dec(&dev->refcnt);
906
907         return 0;
908 }
909
910 static int w1_init(void)
911 {
912         int retval;
913
914         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
915
916         w1_init_netlink();
917
918         retval = bus_register(&w1_bus_type);
919         if (retval) {
920                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
921                 goto err_out_exit_init;
922         }
923
924         retval = driver_register(&w1_master_driver);
925         if (retval) {
926                 printk(KERN_ERR
927                         "Failed to register master driver. err=%d.\n",
928                         retval);
929                 goto err_out_bus_unregister;
930         }
931
932         retval = driver_register(&w1_slave_driver);
933         if (retval) {
934                 printk(KERN_ERR
935                         "Failed to register master driver. err=%d.\n",
936                         retval);
937                 goto err_out_master_unregister;
938         }
939
940         w1_control_thread = kthread_run(w1_control, NULL, "w1_control");
941         if (IS_ERR(w1_control_thread)) {
942                 retval = PTR_ERR(w1_control_thread);
943                 printk(KERN_ERR "Failed to create control thread. err=%d\n",
944                         retval);
945                 goto err_out_slave_unregister;
946         }
947
948         return 0;
949
950 err_out_slave_unregister:
951         driver_unregister(&w1_slave_driver);
952
953 err_out_master_unregister:
954         driver_unregister(&w1_master_driver);
955
956 err_out_bus_unregister:
957         bus_unregister(&w1_bus_type);
958
959 err_out_exit_init:
960         return retval;
961 }
962
963 static void w1_fini(void)
964 {
965         struct w1_master *dev;
966
967         list_for_each_entry(dev, &w1_masters, w1_master_entry)
968                 __w1_remove_master_device(dev);
969
970         w1_fini_netlink();
971
972         kthread_stop(w1_control_thread);
973
974         driver_unregister(&w1_slave_driver);
975         driver_unregister(&w1_master_driver);
976         bus_unregister(&w1_bus_type);
977 }
978
979 module_init(w1_init);
980 module_exit(w1_fini);