xref: /openbmc/linux/drivers/w1/w1.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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, char *buf, loff_t off, size_t count)
109 {
110 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
111 
112 	if (off > 8) {
113 		count = 0;
114 	} else {
115 		if (off + count > 8)
116 			count = 8 - off;
117 
118 		memcpy(buf, (u8 *)&sl->reg_num, count);
119 	}
120 
121 	return count;
122 }
123 
124 static struct device_attribute w1_slave_attr_name =
125 	__ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
126 
127 static struct bin_attribute w1_slave_attr_bin_id = {
128       .attr = {
129               .name = "id",
130               .mode = S_IRUGO,
131               .owner = THIS_MODULE,
132       },
133       .size = 8,
134       .read = w1_slave_read_id,
135 };
136 
137 /* Default family */
138 
139 static ssize_t w1_default_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
140 {
141 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
142 
143 	mutex_lock(&sl->master->mutex);
144 	if (w1_reset_select_slave(sl)) {
145 		count = 0;
146 		goto out_up;
147 	}
148 
149 	w1_write_block(sl->master, buf, count);
150 
151 out_up:
152 	mutex_unlock(&sl->master->mutex);
153 	return count;
154 }
155 
156 static ssize_t w1_default_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
157 {
158 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
159 
160 	mutex_lock(&sl->master->mutex);
161 	w1_read_block(sl->master, buf, count);
162 	mutex_unlock(&sl->master->mutex);
163 	return count;
164 }
165 
166 static struct bin_attribute w1_default_attr = {
167       .attr = {
168               .name = "rw",
169               .mode = S_IRUGO | S_IWUSR,
170               .owner = THIS_MODULE,
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, char **envp, int num_envp, char *buffer, int buffer_size);
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 
255 	return count;
256 }
257 
258 static ssize_t w1_master_attribute_show_search(struct device *dev,
259 					       struct device_attribute *attr,
260 					       char *buf)
261 {
262 	struct w1_master *md = dev_to_w1_master(dev);
263 	ssize_t count;
264 
265 	mutex_lock(&md->mutex);
266 	count = sprintf(buf, "%d\n", md->search_count);
267 	mutex_unlock(&md->mutex);
268 
269 	return count;
270 }
271 
272 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
273 {
274 	struct w1_master *md = dev_to_w1_master(dev);
275 	ssize_t count;
276 
277 	mutex_lock(&md->mutex);
278 	count = sprintf(buf, "0x%p\n", md->bus_master);
279 	mutex_unlock(&md->mutex);
280 	return count;
281 }
282 
283 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
284 {
285 	ssize_t count;
286 	count = sprintf(buf, "%d\n", w1_timeout);
287 	return count;
288 }
289 
290 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
291 {
292 	struct w1_master *md = dev_to_w1_master(dev);
293 	ssize_t count;
294 
295 	mutex_lock(&md->mutex);
296 	count = sprintf(buf, "%d\n", md->max_slave_count);
297 	mutex_unlock(&md->mutex);
298 	return count;
299 }
300 
301 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
302 {
303 	struct w1_master *md = dev_to_w1_master(dev);
304 	ssize_t count;
305 
306 	mutex_lock(&md->mutex);
307 	count = sprintf(buf, "%lu\n", md->attempts);
308 	mutex_unlock(&md->mutex);
309 	return count;
310 }
311 
312 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
313 {
314 	struct w1_master *md = dev_to_w1_master(dev);
315 	ssize_t count;
316 
317 	mutex_lock(&md->mutex);
318 	count = sprintf(buf, "%d\n", md->slave_count);
319 	mutex_unlock(&md->mutex);
320 	return count;
321 }
322 
323 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
324 {
325 	struct w1_master *md = dev_to_w1_master(dev);
326 	int c = PAGE_SIZE;
327 
328 	mutex_lock(&md->mutex);
329 
330 	if (md->slave_count == 0)
331 		c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
332 	else {
333 		struct list_head *ent, *n;
334 		struct w1_slave *sl;
335 
336 		list_for_each_safe(ent, n, &md->slist) {
337 			sl = list_entry(ent, struct w1_slave, w1_slave_entry);
338 
339 			c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
340 		}
341 	}
342 
343 	mutex_unlock(&md->mutex);
344 
345 	return PAGE_SIZE - c;
346 }
347 
348 #define W1_MASTER_ATTR_RO(_name, _mode)				\
349 	struct device_attribute w1_master_attribute_##_name =	\
350 		__ATTR(w1_master_##_name, _mode,		\
351 		       w1_master_attribute_show_##_name, NULL)
352 
353 #define W1_MASTER_ATTR_RW(_name, _mode)				\
354 	struct device_attribute w1_master_attribute_##_name =	\
355 		__ATTR(w1_master_##_name, _mode,		\
356 		       w1_master_attribute_show_##_name,	\
357 		       w1_master_attribute_store_##_name)
358 
359 static W1_MASTER_ATTR_RO(name, S_IRUGO);
360 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
361 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
362 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
363 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
364 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
365 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
366 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
367 
368 static struct attribute *w1_master_default_attrs[] = {
369 	&w1_master_attribute_name.attr,
370 	&w1_master_attribute_slaves.attr,
371 	&w1_master_attribute_slave_count.attr,
372 	&w1_master_attribute_max_slave_count.attr,
373 	&w1_master_attribute_attempts.attr,
374 	&w1_master_attribute_timeout.attr,
375 	&w1_master_attribute_pointer.attr,
376 	&w1_master_attribute_search.attr,
377 	NULL
378 };
379 
380 static struct attribute_group w1_master_defattr_group = {
381 	.attrs = w1_master_default_attrs,
382 };
383 
384 int w1_create_master_attributes(struct w1_master *master)
385 {
386 	return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
387 }
388 
389 static void w1_destroy_master_attributes(struct w1_master *master)
390 {
391 	sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
392 }
393 
394 #ifdef CONFIG_HOTPLUG
395 static int w1_uevent(struct device *dev, char **envp, int num_envp,
396 			char *buffer, int buffer_size)
397 {
398 	struct w1_master *md = NULL;
399 	struct w1_slave *sl = NULL;
400 	char *event_owner, *name;
401 	int err, cur_index=0, cur_len=0;
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(envp, num_envp, &cur_index, buffer, buffer_size,
423 			&cur_len, "W1_FID=%02X", sl->reg_num.family);
424 	if (err)
425 		return err;
426 
427 	err = add_uevent_var(envp, num_envp, &cur_index, buffer, buffer_size,
428 			&cur_len, "W1_SLAVE_ID=%024LX",
429 			(unsigned long long)sl->reg_num.id);
430 	if (err)
431 		return err;
432 
433 	return 0;
434 };
435 #else
436 static int w1_uevent(struct device *dev, char **envp, int num_envp,
437 			char *buffer, int buffer_size)
438 {
439 	return 0;
440 }
441 #endif
442 
443 static int __w1_attach_slave_device(struct w1_slave *sl)
444 {
445 	int err;
446 
447 	sl->dev.parent = &sl->master->dev;
448 	sl->dev.driver = &w1_slave_driver;
449 	sl->dev.bus = &w1_bus_type;
450 	sl->dev.release = &w1_slave_release;
451 
452 	snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
453 		 "%02x-%012llx",
454 		 (unsigned int) sl->reg_num.family,
455 		 (unsigned long long) sl->reg_num.id);
456 	snprintf(&sl->name[0], sizeof(sl->name),
457 		 "%02x-%012llx",
458 		 (unsigned int) sl->reg_num.family,
459 		 (unsigned long long) sl->reg_num.id);
460 
461 	dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
462 		&sl->dev.bus_id[0], sl);
463 
464 	err = device_register(&sl->dev);
465 	if (err < 0) {
466 		dev_err(&sl->dev,
467 			"Device registration [%s] failed. err=%d\n",
468 			sl->dev.bus_id, err);
469 		return err;
470 	}
471 
472 	/* Create "name" entry */
473 	err = device_create_file(&sl->dev, &w1_slave_attr_name);
474 	if (err < 0) {
475 		dev_err(&sl->dev,
476 			"sysfs file creation for [%s] failed. err=%d\n",
477 			sl->dev.bus_id, err);
478 		goto out_unreg;
479 	}
480 
481 	/* Create "id" entry */
482 	err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
483 	if (err < 0) {
484 		dev_err(&sl->dev,
485 			"sysfs file creation for [%s] failed. err=%d\n",
486 			sl->dev.bus_id, err);
487 		goto out_rem1;
488 	}
489 
490 	/* if the family driver needs to initialize something... */
491 	if (sl->family->fops && sl->family->fops->add_slave &&
492 	    ((err = sl->family->fops->add_slave(sl)) < 0)) {
493 		dev_err(&sl->dev,
494 			"sysfs file creation for [%s] failed. err=%d\n",
495 			sl->dev.bus_id, err);
496 		goto out_rem2;
497 	}
498 
499 	list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
500 
501 	return 0;
502 
503 out_rem2:
504 	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
505 out_rem1:
506 	device_remove_file(&sl->dev, &w1_slave_attr_name);
507 out_unreg:
508 	device_unregister(&sl->dev);
509 	return err;
510 }
511 
512 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
513 {
514 	struct w1_slave *sl;
515 	struct w1_family *f;
516 	int err;
517 	struct w1_netlink_msg msg;
518 
519 	sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
520 	if (!sl) {
521 		dev_err(&dev->dev,
522 			 "%s: failed to allocate new slave device.\n",
523 			 __func__);
524 		return -ENOMEM;
525 	}
526 
527 	memset(sl, 0, sizeof(*sl));
528 
529 	sl->owner = THIS_MODULE;
530 	sl->master = dev;
531 	set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
532 
533 	memset(&msg, 0, sizeof(msg));
534 	memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
535 	atomic_set(&sl->refcnt, 0);
536 	init_completion(&sl->released);
537 
538 	spin_lock(&w1_flock);
539 	f = w1_family_registered(rn->family);
540 	if (!f) {
541 		f= &w1_default_family;
542 		dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
543 			  rn->family, rn->family,
544 			  (unsigned long long)rn->id, rn->crc);
545 	}
546 	__w1_family_get(f);
547 	spin_unlock(&w1_flock);
548 
549 	sl->family = f;
550 
551 
552 	err = __w1_attach_slave_device(sl);
553 	if (err < 0) {
554 		dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
555 			 sl->name);
556 		w1_family_put(sl->family);
557 		kfree(sl);
558 		return err;
559 	}
560 
561 	sl->ttl = dev->slave_ttl;
562 	dev->slave_count++;
563 
564 	memcpy(msg.id.id, rn, sizeof(msg.id));
565 	msg.type = W1_SLAVE_ADD;
566 	w1_netlink_send(dev, &msg);
567 
568 	return 0;
569 }
570 
571 static void w1_slave_detach(struct w1_slave *sl)
572 {
573 	struct w1_netlink_msg msg;
574 
575 	dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
576 
577 	list_del(&sl->w1_slave_entry);
578 
579 	if (sl->family->fops && sl->family->fops->remove_slave)
580 		sl->family->fops->remove_slave(sl);
581 
582 	memset(&msg, 0, sizeof(msg));
583 	memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
584 	msg.type = W1_SLAVE_REMOVE;
585 	w1_netlink_send(sl->master, &msg);
586 
587 	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
588 	device_remove_file(&sl->dev, &w1_slave_attr_name);
589 	device_unregister(&sl->dev);
590 
591 	wait_for_completion(&sl->released);
592 	kfree(sl);
593 }
594 
595 static struct w1_master *w1_search_master(void *data)
596 {
597 	struct w1_master *dev;
598 	int found = 0;
599 
600 	mutex_lock(&w1_mlock);
601 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
602 		if (dev->bus_master->data == data) {
603 			found = 1;
604 			atomic_inc(&dev->refcnt);
605 			break;
606 		}
607 	}
608 	mutex_unlock(&w1_mlock);
609 
610 	return (found)?dev:NULL;
611 }
612 
613 struct w1_master *w1_search_master_id(u32 id)
614 {
615 	struct w1_master *dev;
616 	int found = 0;
617 
618 	mutex_lock(&w1_mlock);
619 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
620 		if (dev->id == id) {
621 			found = 1;
622 			atomic_inc(&dev->refcnt);
623 			break;
624 		}
625 	}
626 	mutex_unlock(&w1_mlock);
627 
628 	return (found)?dev:NULL;
629 }
630 
631 struct w1_slave *w1_search_slave(struct w1_reg_num *id)
632 {
633 	struct w1_master *dev;
634 	struct w1_slave *sl = NULL;
635 	int found = 0;
636 
637 	mutex_lock(&w1_mlock);
638 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
639 		mutex_lock(&dev->mutex);
640 		list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
641 			if (sl->reg_num.family == id->family &&
642 					sl->reg_num.id == id->id &&
643 					sl->reg_num.crc == id->crc) {
644 				found = 1;
645 				atomic_inc(&dev->refcnt);
646 				atomic_inc(&sl->refcnt);
647 				break;
648 			}
649 		}
650 		mutex_unlock(&dev->mutex);
651 
652 		if (found)
653 			break;
654 	}
655 	mutex_unlock(&w1_mlock);
656 
657 	return (found)?sl:NULL;
658 }
659 
660 void w1_reconnect_slaves(struct w1_family *f)
661 {
662 	struct w1_master *dev;
663 
664 	mutex_lock(&w1_mlock);
665 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
666 		dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
667 				dev->name, f->fid);
668 		set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
669 	}
670 	mutex_unlock(&w1_mlock);
671 }
672 
673 static void w1_slave_found(void *data, u64 rn)
674 {
675 	int slave_count;
676 	struct w1_slave *sl;
677 	struct list_head *ent;
678 	struct w1_reg_num *tmp;
679 	int family_found = 0;
680 	struct w1_master *dev;
681 	u64 rn_le = cpu_to_le64(rn);
682 
683 	dev = w1_search_master(data);
684 	if (!dev) {
685 		printk(KERN_ERR "Failed to find w1 master device for data %p, "
686 		       "it is impossible.\n", data);
687 		return;
688 	}
689 
690 	tmp = (struct w1_reg_num *) &rn;
691 
692 	slave_count = 0;
693 	list_for_each(ent, &dev->slist) {
694 
695 		sl = list_entry(ent, struct w1_slave, w1_slave_entry);
696 
697 		if (sl->reg_num.family == tmp->family &&
698 		    sl->reg_num.id == tmp->id &&
699 		    sl->reg_num.crc == tmp->crc) {
700 			set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
701 			break;
702 		} else if (sl->reg_num.family == tmp->family) {
703 			family_found = 1;
704 			break;
705 		}
706 
707 		slave_count++;
708 	}
709 
710 	if (slave_count == dev->slave_count &&
711 		rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
712 		w1_attach_slave_device(dev, tmp);
713 	}
714 
715 	atomic_dec(&dev->refcnt);
716 }
717 
718 /**
719  * Performs a ROM Search & registers any devices found.
720  * The 1-wire search is a simple binary tree search.
721  * For each bit of the address, we read two bits and write one bit.
722  * The bit written will put to sleep all devies that don't match that bit.
723  * When the two reads differ, the direction choice is obvious.
724  * When both bits are 0, we must choose a path to take.
725  * When we can scan all 64 bits without having to choose a path, we are done.
726  *
727  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
728  *
729  * @dev        The master device to search
730  * @cb         Function to call when a device is found
731  */
732 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
733 {
734 	u64 last_rn, rn, tmp64;
735 	int i, slave_count = 0;
736 	int last_zero, last_device;
737 	int search_bit, desc_bit;
738 	u8  triplet_ret = 0;
739 
740 	search_bit = 0;
741 	rn = last_rn = 0;
742 	last_device = 0;
743 	last_zero = -1;
744 
745 	desc_bit = 64;
746 
747 	while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
748 		last_rn = rn;
749 		rn = 0;
750 
751 		/*
752 		 * Reset bus and all 1-wire device state machines
753 		 * so they can respond to our requests.
754 		 *
755 		 * Return 0 - device(s) present, 1 - no devices present.
756 		 */
757 		if (w1_reset_bus(dev)) {
758 			dev_dbg(&dev->dev, "No devices present on the wire.\n");
759 			break;
760 		}
761 
762 		/* Start the search */
763 		w1_write_8(dev, search_type);
764 		for (i = 0; i < 64; ++i) {
765 			/* Determine the direction/search bit */
766 			if (i == desc_bit)
767 				search_bit = 1;	  /* took the 0 path last time, so take the 1 path */
768 			else if (i > desc_bit)
769 				search_bit = 0;	  /* take the 0 path on the next branch */
770 			else
771 				search_bit = ((last_rn >> i) & 0x1);
772 
773 			/** Read two bits and write one bit */
774 			triplet_ret = w1_triplet(dev, search_bit);
775 
776 			/* quit if no device responded */
777 			if ( (triplet_ret & 0x03) == 0x03 )
778 				break;
779 
780 			/* If both directions were valid, and we took the 0 path... */
781 			if (triplet_ret == 0)
782 				last_zero = i;
783 
784 			/* extract the direction taken & update the device number */
785 			tmp64 = (triplet_ret >> 2);
786 			rn |= (tmp64 << i);
787 		}
788 
789 		if ( (triplet_ret & 0x03) != 0x03 ) {
790 			if ( (desc_bit == last_zero) || (last_zero < 0))
791 				last_device = 1;
792 			desc_bit = last_zero;
793 			cb(dev->bus_master->data, rn);
794 		}
795 	}
796 }
797 
798 static int w1_control(void *data)
799 {
800 	struct w1_slave *sl, *sln;
801 	struct w1_master *dev, *n;
802 	int have_to_wait = 0;
803 
804 	while (!kthread_should_stop() || have_to_wait) {
805 		have_to_wait = 0;
806 
807 		try_to_freeze();
808 		msleep_interruptible(w1_control_timeout * 1000);
809 
810 		list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
811 			if (!kthread_should_stop() && !dev->flags)
812 				continue;
813 			/*
814 			 * Little race: we can create thread but not set the flag.
815 			 * Get a chance for external process to set flag up.
816 			 */
817 			if (!dev->initialized) {
818 				have_to_wait = 1;
819 				continue;
820 			}
821 
822 			if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
823 				set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
824 
825 				mutex_lock(&w1_mlock);
826 				list_del(&dev->w1_master_entry);
827 				mutex_unlock(&w1_mlock);
828 
829 				mutex_lock(&dev->mutex);
830 				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
831 					w1_slave_detach(sl);
832 				}
833 				w1_destroy_master_attributes(dev);
834 				mutex_unlock(&dev->mutex);
835 				atomic_dec(&dev->refcnt);
836 				continue;
837 			}
838 
839 			if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
840 				dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
841 				mutex_lock(&dev->mutex);
842 				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
843 					if (sl->family->fid == W1_FAMILY_DEFAULT) {
844 						struct w1_reg_num rn;
845 
846 						memcpy(&rn, &sl->reg_num, sizeof(rn));
847 						w1_slave_detach(sl);
848 
849 						w1_attach_slave_device(dev, &rn);
850 					}
851 				}
852 				dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
853 				clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
854 				mutex_unlock(&dev->mutex);
855 			}
856 		}
857 	}
858 
859 	return 0;
860 }
861 
862 void w1_search_process(struct w1_master *dev, u8 search_type)
863 {
864 	struct w1_slave *sl, *sln;
865 
866 	list_for_each_entry(sl, &dev->slist, w1_slave_entry)
867 		clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
868 
869 	w1_search_devices(dev, search_type, w1_slave_found);
870 
871 	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
872 		if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
873 			w1_slave_detach(sl);
874 
875 			dev->slave_count--;
876 		} else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
877 			sl->ttl = dev->slave_ttl;
878 	}
879 
880 	if (dev->search_count > 0)
881 		dev->search_count--;
882 }
883 
884 int w1_process(void *data)
885 {
886 	struct w1_master *dev = (struct w1_master *) data;
887 
888 	while (!kthread_should_stop() && !test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
889 		try_to_freeze();
890 		msleep_interruptible(w1_timeout * 1000);
891 
892 		if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
893 			break;
894 
895 		if (!dev->initialized)
896 			continue;
897 
898 		if (dev->search_count == 0)
899 			continue;
900 
901 		mutex_lock(&dev->mutex);
902 		w1_search_process(dev, W1_SEARCH);
903 		mutex_unlock(&dev->mutex);
904 	}
905 
906 	atomic_dec(&dev->refcnt);
907 
908 	return 0;
909 }
910 
911 static int w1_init(void)
912 {
913 	int retval;
914 
915 	printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
916 
917 	w1_init_netlink();
918 
919 	retval = bus_register(&w1_bus_type);
920 	if (retval) {
921 		printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
922 		goto err_out_exit_init;
923 	}
924 
925 	retval = driver_register(&w1_master_driver);
926 	if (retval) {
927 		printk(KERN_ERR
928 			"Failed to register master driver. err=%d.\n",
929 			retval);
930 		goto err_out_bus_unregister;
931 	}
932 
933 	retval = driver_register(&w1_slave_driver);
934 	if (retval) {
935 		printk(KERN_ERR
936 			"Failed to register master driver. err=%d.\n",
937 			retval);
938 		goto err_out_master_unregister;
939 	}
940 
941 	w1_control_thread = kthread_run(w1_control, NULL, "w1_control");
942 	if (IS_ERR(w1_control_thread)) {
943 		retval = PTR_ERR(w1_control_thread);
944 		printk(KERN_ERR "Failed to create control thread. err=%d\n",
945 			retval);
946 		goto err_out_slave_unregister;
947 	}
948 
949 	return 0;
950 
951 err_out_slave_unregister:
952 	driver_unregister(&w1_slave_driver);
953 
954 err_out_master_unregister:
955 	driver_unregister(&w1_master_driver);
956 
957 err_out_bus_unregister:
958 	bus_unregister(&w1_bus_type);
959 
960 err_out_exit_init:
961 	return retval;
962 }
963 
964 static void w1_fini(void)
965 {
966 	struct w1_master *dev;
967 
968 	list_for_each_entry(dev, &w1_masters, w1_master_entry)
969 		__w1_remove_master_device(dev);
970 
971 	w1_fini_netlink();
972 
973 	kthread_stop(w1_control_thread);
974 
975 	driver_unregister(&w1_slave_driver);
976 	driver_unregister(&w1_master_driver);
977 	bus_unregister(&w1_bus_type);
978 }
979 
980 module_init(w1_init);
981 module_exit(w1_fini);
982