some kmalloc/memset ->kzalloc (tree wide)
[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 static int w1_control_timeout = 1;
50 int w1_max_slave_count = 10;
51 int w1_max_slave_ttl = 10;
52
53 module_param_named(timeout, w1_timeout, int, 0);
54 module_param_named(control_timeout, w1_control_timeout, int, 0);
55 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
56 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
57
58 DEFINE_MUTEX(w1_mlock);
59 LIST_HEAD(w1_masters);
60
61 static struct task_struct *w1_control_thread;
62
63 static int w1_master_match(struct device *dev, struct device_driver *drv)
64 {
65         return 1;
66 }
67
68 static int w1_master_probe(struct device *dev)
69 {
70         return -ENODEV;
71 }
72
73 static void w1_master_release(struct device *dev)
74 {
75         struct w1_master *md = dev_to_w1_master(dev);
76
77         dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
78         memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
79         kfree(md);
80 }
81
82 static void w1_slave_release(struct device *dev)
83 {
84         struct w1_slave *sl = dev_to_w1_slave(dev);
85
86         printk("%s: Releasing %s.\n", __func__, sl->name);
87
88         while (atomic_read(&sl->refcnt)) {
89                 printk("Waiting for %s to become free: refcnt=%d.\n",
90                                 sl->name, atomic_read(&sl->refcnt));
91                 if (msleep_interruptible(1000))
92                         flush_signals(current);
93         }
94
95         w1_family_put(sl->family);
96         sl->master->slave_count--;
97
98         complete(&sl->released);
99 }
100
101 static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
102 {
103         struct w1_slave *sl = dev_to_w1_slave(dev);
104
105         return sprintf(buf, "%s\n", sl->name);
106 }
107
108 static ssize_t w1_slave_read_id(struct kobject *kobj,
109                                 struct bin_attribute *bin_attr,
110                                 char *buf, loff_t off, size_t count)
111 {
112         struct w1_slave *sl = kobj_to_w1_slave(kobj);
113
114         if (off > 8) {
115                 count = 0;
116         } else {
117                 if (off + count > 8)
118                         count = 8 - off;
119
120                 memcpy(buf, (u8 *)&sl->reg_num, count);
121         }
122
123         return count;
124 }
125
126 static struct device_attribute w1_slave_attr_name =
127         __ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
128
129 static struct bin_attribute w1_slave_attr_bin_id = {
130       .attr = {
131               .name = "id",
132               .mode = S_IRUGO,
133       },
134       .size = 8,
135       .read = w1_slave_read_id,
136 };
137
138 /* Default family */
139
140 static ssize_t w1_default_write(struct kobject *kobj,
141                                 struct bin_attribute *bin_attr,
142                                 char *buf, loff_t off, size_t count)
143 {
144         struct w1_slave *sl = kobj_to_w1_slave(kobj);
145
146         mutex_lock(&sl->master->mutex);
147         if (w1_reset_select_slave(sl)) {
148                 count = 0;
149                 goto out_up;
150         }
151
152         w1_write_block(sl->master, buf, count);
153
154 out_up:
155         mutex_unlock(&sl->master->mutex);
156         return count;
157 }
158
159 static ssize_t w1_default_read(struct kobject *kobj,
160                                struct bin_attribute *bin_attr,
161                                char *buf, loff_t off, size_t count)
162 {
163         struct w1_slave *sl = kobj_to_w1_slave(kobj);
164
165         mutex_lock(&sl->master->mutex);
166         w1_read_block(sl->master, buf, count);
167         mutex_unlock(&sl->master->mutex);
168         return count;
169 }
170
171 static struct bin_attribute w1_default_attr = {
172       .attr = {
173               .name = "rw",
174               .mode = S_IRUGO | S_IWUSR,
175       },
176       .size = PAGE_SIZE,
177       .read = w1_default_read,
178       .write = w1_default_write,
179 };
180
181 static int w1_default_add_slave(struct w1_slave *sl)
182 {
183         return sysfs_create_bin_file(&sl->dev.kobj, &w1_default_attr);
184 }
185
186 static void w1_default_remove_slave(struct w1_slave *sl)
187 {
188         sysfs_remove_bin_file(&sl->dev.kobj, &w1_default_attr);
189 }
190
191 static struct w1_family_ops w1_default_fops = {
192         .add_slave      = w1_default_add_slave,
193         .remove_slave   = w1_default_remove_slave,
194 };
195
196 static struct w1_family w1_default_family = {
197         .fops = &w1_default_fops,
198 };
199
200 static int w1_uevent(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size);
201
202 static struct bus_type w1_bus_type = {
203         .name = "w1",
204         .match = w1_master_match,
205         .uevent = w1_uevent,
206 };
207
208 struct device_driver w1_master_driver = {
209         .name = "w1_master_driver",
210         .bus = &w1_bus_type,
211         .probe = w1_master_probe,
212 };
213
214 struct device w1_master_device = {
215         .parent = NULL,
216         .bus = &w1_bus_type,
217         .bus_id = "w1 bus master",
218         .driver = &w1_master_driver,
219         .release = &w1_master_release
220 };
221
222 static struct device_driver w1_slave_driver = {
223         .name = "w1_slave_driver",
224         .bus = &w1_bus_type,
225 };
226
227 #if 0
228 struct device w1_slave_device = {
229         .parent = NULL,
230         .bus = &w1_bus_type,
231         .bus_id = "w1 bus slave",
232         .driver = &w1_slave_driver,
233         .release = &w1_slave_release
234 };
235 #endif  /*  0  */
236
237 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
238 {
239         struct w1_master *md = dev_to_w1_master(dev);
240         ssize_t count;
241
242         mutex_lock(&md->mutex);
243         count = sprintf(buf, "%s\n", md->name);
244         mutex_unlock(&md->mutex);
245
246         return count;
247 }
248
249 static ssize_t w1_master_attribute_store_search(struct device * dev,
250                                                 struct device_attribute *attr,
251                                                 const char * buf, size_t count)
252 {
253         struct w1_master *md = dev_to_w1_master(dev);
254
255         mutex_lock(&md->mutex);
256         md->search_count = simple_strtol(buf, NULL, 0);
257         mutex_unlock(&md->mutex);
258
259         return count;
260 }
261
262 static ssize_t w1_master_attribute_show_search(struct device *dev,
263                                                struct device_attribute *attr,
264                                                char *buf)
265 {
266         struct w1_master *md = dev_to_w1_master(dev);
267         ssize_t count;
268
269         mutex_lock(&md->mutex);
270         count = sprintf(buf, "%d\n", md->search_count);
271         mutex_unlock(&md->mutex);
272
273         return count;
274 }
275
276 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
277 {
278         struct w1_master *md = dev_to_w1_master(dev);
279         ssize_t count;
280
281         mutex_lock(&md->mutex);
282         count = sprintf(buf, "0x%p\n", md->bus_master);
283         mutex_unlock(&md->mutex);
284         return count;
285 }
286
287 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
288 {
289         ssize_t count;
290         count = sprintf(buf, "%d\n", w1_timeout);
291         return count;
292 }
293
294 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
295 {
296         struct w1_master *md = dev_to_w1_master(dev);
297         ssize_t count;
298
299         mutex_lock(&md->mutex);
300         count = sprintf(buf, "%d\n", md->max_slave_count);
301         mutex_unlock(&md->mutex);
302         return count;
303 }
304
305 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
306 {
307         struct w1_master *md = dev_to_w1_master(dev);
308         ssize_t count;
309
310         mutex_lock(&md->mutex);
311         count = sprintf(buf, "%lu\n", md->attempts);
312         mutex_unlock(&md->mutex);
313         return count;
314 }
315
316 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
317 {
318         struct w1_master *md = dev_to_w1_master(dev);
319         ssize_t count;
320
321         mutex_lock(&md->mutex);
322         count = sprintf(buf, "%d\n", md->slave_count);
323         mutex_unlock(&md->mutex);
324         return count;
325 }
326
327 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
328 {
329         struct w1_master *md = dev_to_w1_master(dev);
330         int c = PAGE_SIZE;
331
332         mutex_lock(&md->mutex);
333
334         if (md->slave_count == 0)
335                 c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
336         else {
337                 struct list_head *ent, *n;
338                 struct w1_slave *sl;
339
340                 list_for_each_safe(ent, n, &md->slist) {
341                         sl = list_entry(ent, struct w1_slave, w1_slave_entry);
342
343                         c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
344                 }
345         }
346
347         mutex_unlock(&md->mutex);
348
349         return PAGE_SIZE - c;
350 }
351
352 #define W1_MASTER_ATTR_RO(_name, _mode)                         \
353         struct device_attribute w1_master_attribute_##_name =   \
354                 __ATTR(w1_master_##_name, _mode,                \
355                        w1_master_attribute_show_##_name, NULL)
356
357 #define W1_MASTER_ATTR_RW(_name, _mode)                         \
358         struct device_attribute w1_master_attribute_##_name =   \
359                 __ATTR(w1_master_##_name, _mode,                \
360                        w1_master_attribute_show_##_name,        \
361                        w1_master_attribute_store_##_name)
362
363 static W1_MASTER_ATTR_RO(name, S_IRUGO);
364 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
365 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
366 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
367 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
368 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
369 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
370 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
371
372 static struct attribute *w1_master_default_attrs[] = {
373         &w1_master_attribute_name.attr,
374         &w1_master_attribute_slaves.attr,
375         &w1_master_attribute_slave_count.attr,
376         &w1_master_attribute_max_slave_count.attr,
377         &w1_master_attribute_attempts.attr,
378         &w1_master_attribute_timeout.attr,
379         &w1_master_attribute_pointer.attr,
380         &w1_master_attribute_search.attr,
381         NULL
382 };
383
384 static struct attribute_group w1_master_defattr_group = {
385         .attrs = w1_master_default_attrs,
386 };
387
388 int w1_create_master_attributes(struct w1_master *master)
389 {
390         return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
391 }
392
393 static void w1_destroy_master_attributes(struct w1_master *master)
394 {
395         sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
396 }
397
398 #ifdef CONFIG_HOTPLUG
399 static int w1_uevent(struct device *dev, char **envp, int num_envp,
400                         char *buffer, int buffer_size)
401 {
402         struct w1_master *md = NULL;
403         struct w1_slave *sl = NULL;
404         char *event_owner, *name;
405         int err, cur_index=0, cur_len=0;
406
407         if (dev->driver == &w1_master_driver) {
408                 md = container_of(dev, struct w1_master, dev);
409                 event_owner = "master";
410                 name = md->name;
411         } else if (dev->driver == &w1_slave_driver) {
412                 sl = container_of(dev, struct w1_slave, dev);
413                 event_owner = "slave";
414                 name = sl->name;
415         } else {
416                 dev_dbg(dev, "Unknown event.\n");
417                 return -EINVAL;
418         }
419
420         dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
421                         event_owner, name, dev->bus_id);
422
423         if (dev->driver != &w1_slave_driver || !sl)
424                 return 0;
425
426         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
427                         &cur_len, "W1_FID=%02X", sl->reg_num.family);
428         if (err)
429                 return err;
430
431         err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
432                         &cur_len, "W1_SLAVE_ID=%024LX",
433                         (unsigned long long)sl->reg_num.id);
434         if (err)
435                 return err;
436
437         return 0;
438 };
439 #else
440 static int w1_uevent(struct device *dev, char **envp, int num_envp,
441                         char *buffer, int buffer_size)
442 {
443         return 0;
444 }
445 #endif
446
447 static int __w1_attach_slave_device(struct w1_slave *sl)
448 {
449         int err;
450
451         sl->dev.parent = &sl->master->dev;
452         sl->dev.driver = &w1_slave_driver;
453         sl->dev.bus = &w1_bus_type;
454         sl->dev.release = &w1_slave_release;
455
456         snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
457                  "%02x-%012llx",
458                  (unsigned int) sl->reg_num.family,
459                  (unsigned long long) sl->reg_num.id);
460         snprintf(&sl->name[0], sizeof(sl->name),
461                  "%02x-%012llx",
462                  (unsigned int) sl->reg_num.family,
463                  (unsigned long long) sl->reg_num.id);
464
465         dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
466                 &sl->dev.bus_id[0], sl);
467
468         err = device_register(&sl->dev);
469         if (err < 0) {
470                 dev_err(&sl->dev,
471                         "Device registration [%s] failed. err=%d\n",
472                         sl->dev.bus_id, err);
473                 return err;
474         }
475
476         /* Create "name" entry */
477         err = device_create_file(&sl->dev, &w1_slave_attr_name);
478         if (err < 0) {
479                 dev_err(&sl->dev,
480                         "sysfs file creation for [%s] failed. err=%d\n",
481                         sl->dev.bus_id, err);
482                 goto out_unreg;
483         }
484
485         /* Create "id" entry */
486         err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
487         if (err < 0) {
488                 dev_err(&sl->dev,
489                         "sysfs file creation for [%s] failed. err=%d\n",
490                         sl->dev.bus_id, err);
491                 goto out_rem1;
492         }
493
494         /* if the family driver needs to initialize something... */
495         if (sl->family->fops && sl->family->fops->add_slave &&
496             ((err = sl->family->fops->add_slave(sl)) < 0)) {
497                 dev_err(&sl->dev,
498                         "sysfs file creation for [%s] failed. err=%d\n",
499                         sl->dev.bus_id, err);
500                 goto out_rem2;
501         }
502
503         list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
504
505         return 0;
506
507 out_rem2:
508         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
509 out_rem1:
510         device_remove_file(&sl->dev, &w1_slave_attr_name);
511 out_unreg:
512         device_unregister(&sl->dev);
513         return err;
514 }
515
516 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
517 {
518         struct w1_slave *sl;
519         struct w1_family *f;
520         int err;
521         struct w1_netlink_msg msg;
522
523         sl = kzalloc(sizeof(struct w1_slave), GFP_KERNEL);
524         if (!sl) {
525                 dev_err(&dev->dev,
526                          "%s: failed to allocate new slave device.\n",
527                          __func__);
528                 return -ENOMEM;
529         }
530
531
532         sl->owner = THIS_MODULE;
533         sl->master = dev;
534         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
535
536         memset(&msg, 0, sizeof(msg));
537         memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
538         atomic_set(&sl->refcnt, 0);
539         init_completion(&sl->released);
540
541         spin_lock(&w1_flock);
542         f = w1_family_registered(rn->family);
543         if (!f) {
544                 f= &w1_default_family;
545                 dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
546                           rn->family, rn->family,
547                           (unsigned long long)rn->id, rn->crc);
548         }
549         __w1_family_get(f);
550         spin_unlock(&w1_flock);
551
552         sl->family = f;
553
554
555         err = __w1_attach_slave_device(sl);
556         if (err < 0) {
557                 dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
558                          sl->name);
559                 w1_family_put(sl->family);
560                 kfree(sl);
561                 return err;
562         }
563
564         sl->ttl = dev->slave_ttl;
565         dev->slave_count++;
566
567         memcpy(msg.id.id, rn, sizeof(msg.id));
568         msg.type = W1_SLAVE_ADD;
569         w1_netlink_send(dev, &msg);
570
571         return 0;
572 }
573
574 static void w1_slave_detach(struct w1_slave *sl)
575 {
576         struct w1_netlink_msg msg;
577
578         dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
579
580         list_del(&sl->w1_slave_entry);
581
582         if (sl->family->fops && sl->family->fops->remove_slave)
583                 sl->family->fops->remove_slave(sl);
584
585         memset(&msg, 0, sizeof(msg));
586         memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
587         msg.type = W1_SLAVE_REMOVE;
588         w1_netlink_send(sl->master, &msg);
589
590         sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
591         device_remove_file(&sl->dev, &w1_slave_attr_name);
592         device_unregister(&sl->dev);
593
594         wait_for_completion(&sl->released);
595         kfree(sl);
596 }
597
598 static struct w1_master *w1_search_master(void *data)
599 {
600         struct w1_master *dev;
601         int found = 0;
602
603         mutex_lock(&w1_mlock);
604         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
605                 if (dev->bus_master->data == data) {
606                         found = 1;
607                         atomic_inc(&dev->refcnt);
608                         break;
609                 }
610         }
611         mutex_unlock(&w1_mlock);
612
613         return (found)?dev:NULL;
614 }
615
616 struct w1_master *w1_search_master_id(u32 id)
617 {
618         struct w1_master *dev;
619         int found = 0;
620
621         mutex_lock(&w1_mlock);
622         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
623                 if (dev->id == id) {
624                         found = 1;
625                         atomic_inc(&dev->refcnt);
626                         break;
627                 }
628         }
629         mutex_unlock(&w1_mlock);
630
631         return (found)?dev:NULL;
632 }
633
634 struct w1_slave *w1_search_slave(struct w1_reg_num *id)
635 {
636         struct w1_master *dev;
637         struct w1_slave *sl = NULL;
638         int found = 0;
639
640         mutex_lock(&w1_mlock);
641         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
642                 mutex_lock(&dev->mutex);
643                 list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
644                         if (sl->reg_num.family == id->family &&
645                                         sl->reg_num.id == id->id &&
646                                         sl->reg_num.crc == id->crc) {
647                                 found = 1;
648                                 atomic_inc(&dev->refcnt);
649                                 atomic_inc(&sl->refcnt);
650                                 break;
651                         }
652                 }
653                 mutex_unlock(&dev->mutex);
654
655                 if (found)
656                         break;
657         }
658         mutex_unlock(&w1_mlock);
659
660         return (found)?sl:NULL;
661 }
662
663 void w1_reconnect_slaves(struct w1_family *f)
664 {
665         struct w1_master *dev;
666
667         mutex_lock(&w1_mlock);
668         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
669                 dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
670                                 dev->name, f->fid);
671                 set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
672         }
673         mutex_unlock(&w1_mlock);
674 }
675
676 static void w1_slave_found(void *data, u64 rn)
677 {
678         int slave_count;
679         struct w1_slave *sl;
680         struct list_head *ent;
681         struct w1_reg_num *tmp;
682         int family_found = 0;
683         struct w1_master *dev;
684         u64 rn_le = cpu_to_le64(rn);
685
686         dev = w1_search_master(data);
687         if (!dev) {
688                 printk(KERN_ERR "Failed to find w1 master device for data %p, "
689                        "it is impossible.\n", data);
690                 return;
691         }
692
693         tmp = (struct w1_reg_num *) &rn;
694
695         slave_count = 0;
696         list_for_each(ent, &dev->slist) {
697
698                 sl = list_entry(ent, struct w1_slave, w1_slave_entry);
699
700                 if (sl->reg_num.family == tmp->family &&
701                     sl->reg_num.id == tmp->id &&
702                     sl->reg_num.crc == tmp->crc) {
703                         set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
704                         break;
705                 } else if (sl->reg_num.family == tmp->family) {
706                         family_found = 1;
707                         break;
708                 }
709
710                 slave_count++;
711         }
712
713         if (slave_count == dev->slave_count &&
714                 rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
715                 w1_attach_slave_device(dev, tmp);
716         }
717
718         atomic_dec(&dev->refcnt);
719 }
720
721 /**
722  * Performs a ROM Search & registers any devices found.
723  * The 1-wire search is a simple binary tree search.
724  * For each bit of the address, we read two bits and write one bit.
725  * The bit written will put to sleep all devies that don't match that bit.
726  * When the two reads differ, the direction choice is obvious.
727  * When both bits are 0, we must choose a path to take.
728  * When we can scan all 64 bits without having to choose a path, we are done.
729  *
730  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
731  *
732  * @dev        The master device to search
733  * @cb         Function to call when a device is found
734  */
735 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
736 {
737         u64 last_rn, rn, tmp64;
738         int i, slave_count = 0;
739         int last_zero, last_device;
740         int search_bit, desc_bit;
741         u8  triplet_ret = 0;
742
743         search_bit = 0;
744         rn = last_rn = 0;
745         last_device = 0;
746         last_zero = -1;
747
748         desc_bit = 64;
749
750         while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
751                 last_rn = rn;
752                 rn = 0;
753
754                 /*
755                  * Reset bus and all 1-wire device state machines
756                  * so they can respond to our requests.
757                  *
758                  * Return 0 - device(s) present, 1 - no devices present.
759                  */
760                 if (w1_reset_bus(dev)) {
761                         dev_dbg(&dev->dev, "No devices present on the wire.\n");
762                         break;
763                 }
764
765                 /* Start the search */
766                 w1_write_8(dev, search_type);
767                 for (i = 0; i < 64; ++i) {
768                         /* Determine the direction/search bit */
769                         if (i == desc_bit)
770                                 search_bit = 1;   /* took the 0 path last time, so take the 1 path */
771                         else if (i > desc_bit)
772                                 search_bit = 0;   /* take the 0 path on the next branch */
773                         else
774                                 search_bit = ((last_rn >> i) & 0x1);
775
776                         /** Read two bits and write one bit */
777                         triplet_ret = w1_triplet(dev, search_bit);
778
779                         /* quit if no device responded */
780                         if ( (triplet_ret & 0x03) == 0x03 )
781                                 break;
782
783                         /* If both directions were valid, and we took the 0 path... */
784                         if (triplet_ret == 0)
785                                 last_zero = i;
786
787                         /* extract the direction taken & update the device number */
788                         tmp64 = (triplet_ret >> 2);
789                         rn |= (tmp64 << i);
790                 }
791
792                 if ( (triplet_ret & 0x03) != 0x03 ) {
793                         if ( (desc_bit == last_zero) || (last_zero < 0))
794                                 last_device = 1;
795                         desc_bit = last_zero;
796                         cb(dev->bus_master->data, rn);
797                 }
798         }
799 }
800
801 static int w1_control(void *data)
802 {
803         struct w1_slave *sl, *sln;
804         struct w1_master *dev, *n;
805         int have_to_wait = 0;
806
807         set_freezable();
808         while (!kthread_should_stop() || have_to_wait) {
809                 have_to_wait = 0;
810
811                 try_to_freeze();
812                 msleep_interruptible(w1_control_timeout * 1000);
813
814                 list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
815                         if (!kthread_should_stop() && !dev->flags)
816                                 continue;
817                         /*
818                          * Little race: we can create thread but not set the flag.
819                          * Get a chance for external process to set flag up.
820                          */
821                         if (!dev->initialized) {
822                                 have_to_wait = 1;
823                                 continue;
824                         }
825
826                         if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
827                                 set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
828
829                                 mutex_lock(&w1_mlock);
830                                 list_del(&dev->w1_master_entry);
831                                 mutex_unlock(&w1_mlock);
832
833                                 mutex_lock(&dev->mutex);
834                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
835                                         w1_slave_detach(sl);
836                                 }
837                                 w1_destroy_master_attributes(dev);
838                                 mutex_unlock(&dev->mutex);
839                                 atomic_dec(&dev->refcnt);
840                                 continue;
841                         }
842
843                         if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
844                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
845                                 mutex_lock(&dev->mutex);
846                                 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
847                                         if (sl->family->fid == W1_FAMILY_DEFAULT) {
848                                                 struct w1_reg_num rn;
849
850                                                 memcpy(&rn, &sl->reg_num, sizeof(rn));
851                                                 w1_slave_detach(sl);
852
853                                                 w1_attach_slave_device(dev, &rn);
854                                         }
855                                 }
856                                 dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
857                                 clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
858                                 mutex_unlock(&dev->mutex);
859                         }
860                 }
861         }
862
863         return 0;
864 }
865
866 void w1_search_process(struct w1_master *dev, u8 search_type)
867 {
868         struct w1_slave *sl, *sln;
869
870         list_for_each_entry(sl, &dev->slist, w1_slave_entry)
871                 clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
872
873         w1_search_devices(dev, search_type, w1_slave_found);
874
875         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
876                 if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
877                         w1_slave_detach(sl);
878
879                         dev->slave_count--;
880                 } else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
881                         sl->ttl = dev->slave_ttl;
882         }
883
884         if (dev->search_count > 0)
885                 dev->search_count--;
886 }
887
888 int w1_process(void *data)
889 {
890         struct w1_master *dev = (struct w1_master *) data;
891
892         while (!kthread_should_stop() && !test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
893                 try_to_freeze();
894                 msleep_interruptible(w1_timeout * 1000);
895
896                 if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
897                         break;
898
899                 if (!dev->initialized)
900                         continue;
901
902                 if (dev->search_count == 0)
903                         continue;
904
905                 mutex_lock(&dev->mutex);
906                 w1_search_process(dev, W1_SEARCH);
907                 mutex_unlock(&dev->mutex);
908         }
909
910         atomic_dec(&dev->refcnt);
911
912         return 0;
913 }
914
915 static int w1_init(void)
916 {
917         int retval;
918
919         printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
920
921         w1_init_netlink();
922
923         retval = bus_register(&w1_bus_type);
924         if (retval) {
925                 printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
926                 goto err_out_exit_init;
927         }
928
929         retval = driver_register(&w1_master_driver);
930         if (retval) {
931                 printk(KERN_ERR
932                         "Failed to register master driver. err=%d.\n",
933                         retval);
934                 goto err_out_bus_unregister;
935         }
936
937         retval = driver_register(&w1_slave_driver);
938         if (retval) {
939                 printk(KERN_ERR
940                         "Failed to register master driver. err=%d.\n",
941                         retval);
942                 goto err_out_master_unregister;
943         }
944
945         w1_control_thread = kthread_run(w1_control, NULL, "w1_control");
946         if (IS_ERR(w1_control_thread)) {
947                 retval = PTR_ERR(w1_control_thread);
948                 printk(KERN_ERR "Failed to create control thread. err=%d\n",
949                         retval);
950                 goto err_out_slave_unregister;
951         }
952
953         return 0;
954
955 err_out_slave_unregister:
956         driver_unregister(&w1_slave_driver);
957
958 err_out_master_unregister:
959         driver_unregister(&w1_master_driver);
960
961 err_out_bus_unregister:
962         bus_unregister(&w1_bus_type);
963
964 err_out_exit_init:
965         return retval;
966 }
967
968 static void w1_fini(void)
969 {
970         struct w1_master *dev;
971
972         list_for_each_entry(dev, &w1_masters, w1_master_entry)
973                 __w1_remove_master_device(dev);
974
975         w1_fini_netlink();
976
977         kthread_stop(w1_control_thread);
978
979         driver_unregister(&w1_slave_driver);
980         driver_unregister(&w1_master_driver);
981         bus_unregister(&w1_bus_type);
982 }
983
984 module_init(w1_init);
985 module_exit(w1_fini);