xref: /openbmc/linux/drivers/w1/w1.c (revision 22246614)
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, struct kobj_uevent_env *env);
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, struct kobj_uevent_env *env)
400 {
401 	struct w1_master *md = NULL;
402 	struct w1_slave *sl = NULL;
403 	char *event_owner, *name;
404 	int err;
405 
406 	if (dev->driver == &w1_master_driver) {
407 		md = container_of(dev, struct w1_master, dev);
408 		event_owner = "master";
409 		name = md->name;
410 	} else if (dev->driver == &w1_slave_driver) {
411 		sl = container_of(dev, struct w1_slave, dev);
412 		event_owner = "slave";
413 		name = sl->name;
414 	} else {
415 		dev_dbg(dev, "Unknown event.\n");
416 		return -EINVAL;
417 	}
418 
419 	dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
420 			event_owner, name, dev->bus_id);
421 
422 	if (dev->driver != &w1_slave_driver || !sl)
423 		return 0;
424 
425 	err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
426 	if (err)
427 		return err;
428 
429 	err = add_uevent_var(env, "W1_SLAVE_ID=%024LX",
430 			     (unsigned long long)sl->reg_num.id);
431 	if (err)
432 		return err;
433 
434 	return 0;
435 };
436 #else
437 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
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 = kzalloc(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 
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 	struct w1_master *dev;
679 	u64 rn_le = cpu_to_le64(rn);
680 
681 	dev = w1_search_master(data);
682 	if (!dev) {
683 		printk(KERN_ERR "Failed to find w1 master device for data %p, "
684 		       "it is impossible.\n", data);
685 		return;
686 	}
687 
688 	tmp = (struct w1_reg_num *) &rn;
689 
690 	slave_count = 0;
691 	list_for_each(ent, &dev->slist) {
692 
693 		sl = list_entry(ent, struct w1_slave, w1_slave_entry);
694 
695 		if (sl->reg_num.family == tmp->family &&
696 		    sl->reg_num.id == tmp->id &&
697 		    sl->reg_num.crc == tmp->crc) {
698 			set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
699 			break;
700 		}
701 
702 		slave_count++;
703 	}
704 
705 	if (slave_count == dev->slave_count &&
706 		rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
707 		w1_attach_slave_device(dev, tmp);
708 	}
709 
710 	atomic_dec(&dev->refcnt);
711 }
712 
713 /**
714  * Performs a ROM Search & registers any devices found.
715  * The 1-wire search is a simple binary tree search.
716  * For each bit of the address, we read two bits and write one bit.
717  * The bit written will put to sleep all devies that don't match that bit.
718  * When the two reads differ, the direction choice is obvious.
719  * When both bits are 0, we must choose a path to take.
720  * When we can scan all 64 bits without having to choose a path, we are done.
721  *
722  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
723  *
724  * @dev        The master device to search
725  * @cb         Function to call when a device is found
726  */
727 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
728 {
729 	u64 last_rn, rn, tmp64;
730 	int i, slave_count = 0;
731 	int last_zero, last_device;
732 	int search_bit, desc_bit;
733 	u8  triplet_ret = 0;
734 
735 	search_bit = 0;
736 	rn = last_rn = 0;
737 	last_device = 0;
738 	last_zero = -1;
739 
740 	desc_bit = 64;
741 
742 	while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
743 		last_rn = rn;
744 		rn = 0;
745 
746 		/*
747 		 * Reset bus and all 1-wire device state machines
748 		 * so they can respond to our requests.
749 		 *
750 		 * Return 0 - device(s) present, 1 - no devices present.
751 		 */
752 		if (w1_reset_bus(dev)) {
753 			dev_dbg(&dev->dev, "No devices present on the wire.\n");
754 			break;
755 		}
756 
757 		/* Start the search */
758 		w1_write_8(dev, search_type);
759 		for (i = 0; i < 64; ++i) {
760 			/* Determine the direction/search bit */
761 			if (i == desc_bit)
762 				search_bit = 1;	  /* took the 0 path last time, so take the 1 path */
763 			else if (i > desc_bit)
764 				search_bit = 0;	  /* take the 0 path on the next branch */
765 			else
766 				search_bit = ((last_rn >> i) & 0x1);
767 
768 			/** Read two bits and write one bit */
769 			triplet_ret = w1_triplet(dev, search_bit);
770 
771 			/* quit if no device responded */
772 			if ( (triplet_ret & 0x03) == 0x03 )
773 				break;
774 
775 			/* If both directions were valid, and we took the 0 path... */
776 			if (triplet_ret == 0)
777 				last_zero = i;
778 
779 			/* extract the direction taken & update the device number */
780 			tmp64 = (triplet_ret >> 2);
781 			rn |= (tmp64 << i);
782 		}
783 
784 		if ( (triplet_ret & 0x03) != 0x03 ) {
785 			if ( (desc_bit == last_zero) || (last_zero < 0))
786 				last_device = 1;
787 			desc_bit = last_zero;
788 			cb(dev->bus_master->data, rn);
789 		}
790 	}
791 }
792 
793 static int w1_control(void *data)
794 {
795 	struct w1_slave *sl, *sln;
796 	struct w1_master *dev, *n;
797 	int have_to_wait = 0;
798 
799 	set_freezable();
800 	while (!kthread_should_stop() || have_to_wait) {
801 		have_to_wait = 0;
802 
803 		try_to_freeze();
804 		msleep_interruptible(w1_control_timeout * 1000);
805 
806 		list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
807 			if (!kthread_should_stop() && !dev->flags)
808 				continue;
809 			/*
810 			 * Little race: we can create thread but not set the flag.
811 			 * Get a chance for external process to set flag up.
812 			 */
813 			if (!dev->initialized) {
814 				have_to_wait = 1;
815 				continue;
816 			}
817 
818 			if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
819 				set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
820 
821 				mutex_lock(&w1_mlock);
822 				list_del(&dev->w1_master_entry);
823 				mutex_unlock(&w1_mlock);
824 
825 				mutex_lock(&dev->mutex);
826 				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
827 					w1_slave_detach(sl);
828 				}
829 				w1_destroy_master_attributes(dev);
830 				mutex_unlock(&dev->mutex);
831 				atomic_dec(&dev->refcnt);
832 				continue;
833 			}
834 
835 			if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
836 				dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
837 				mutex_lock(&dev->mutex);
838 				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
839 					if (sl->family->fid == W1_FAMILY_DEFAULT) {
840 						struct w1_reg_num rn;
841 
842 						memcpy(&rn, &sl->reg_num, sizeof(rn));
843 						w1_slave_detach(sl);
844 
845 						w1_attach_slave_device(dev, &rn);
846 					}
847 				}
848 				dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
849 				clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
850 				mutex_unlock(&dev->mutex);
851 			}
852 		}
853 	}
854 
855 	return 0;
856 }
857 
858 void w1_search_process(struct w1_master *dev, u8 search_type)
859 {
860 	struct w1_slave *sl, *sln;
861 
862 	list_for_each_entry(sl, &dev->slist, w1_slave_entry)
863 		clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
864 
865 	w1_search_devices(dev, search_type, w1_slave_found);
866 
867 	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
868 		if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl)
869 			w1_slave_detach(sl);
870 		else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
871 			sl->ttl = dev->slave_ttl;
872 	}
873 
874 	if (dev->search_count > 0)
875 		dev->search_count--;
876 }
877 
878 int w1_process(void *data)
879 {
880 	struct w1_master *dev = (struct w1_master *) data;
881 
882 	while (!kthread_should_stop() && !test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
883 		try_to_freeze();
884 		msleep_interruptible(w1_timeout * 1000);
885 
886 		if (kthread_should_stop() || test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
887 			break;
888 
889 		if (!dev->initialized)
890 			continue;
891 
892 		if (dev->search_count == 0)
893 			continue;
894 
895 		mutex_lock(&dev->mutex);
896 		w1_search_process(dev, W1_SEARCH);
897 		mutex_unlock(&dev->mutex);
898 	}
899 
900 	atomic_dec(&dev->refcnt);
901 
902 	return 0;
903 }
904 
905 static int w1_init(void)
906 {
907 	int retval;
908 
909 	printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
910 
911 	w1_init_netlink();
912 
913 	retval = bus_register(&w1_bus_type);
914 	if (retval) {
915 		printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
916 		goto err_out_exit_init;
917 	}
918 
919 	retval = driver_register(&w1_master_driver);
920 	if (retval) {
921 		printk(KERN_ERR
922 			"Failed to register master driver. err=%d.\n",
923 			retval);
924 		goto err_out_bus_unregister;
925 	}
926 
927 	retval = driver_register(&w1_slave_driver);
928 	if (retval) {
929 		printk(KERN_ERR
930 			"Failed to register master driver. err=%d.\n",
931 			retval);
932 		goto err_out_master_unregister;
933 	}
934 
935 	w1_control_thread = kthread_run(w1_control, NULL, "w1_control");
936 	if (IS_ERR(w1_control_thread)) {
937 		retval = PTR_ERR(w1_control_thread);
938 		printk(KERN_ERR "Failed to create control thread. err=%d\n",
939 			retval);
940 		goto err_out_slave_unregister;
941 	}
942 
943 	return 0;
944 
945 err_out_slave_unregister:
946 	driver_unregister(&w1_slave_driver);
947 
948 err_out_master_unregister:
949 	driver_unregister(&w1_master_driver);
950 
951 err_out_bus_unregister:
952 	bus_unregister(&w1_bus_type);
953 
954 err_out_exit_init:
955 	return retval;
956 }
957 
958 static void w1_fini(void)
959 {
960 	struct w1_master *dev;
961 
962 	list_for_each_entry(dev, &w1_masters, w1_master_entry)
963 		__w1_remove_master_device(dev);
964 
965 	w1_fini_netlink();
966 
967 	kthread_stop(w1_control_thread);
968 
969 	driver_unregister(&w1_slave_driver);
970 	driver_unregister(&w1_master_driver);
971 	bus_unregister(&w1_bus_type);
972 }
973 
974 module_init(w1_init);
975 module_exit(w1_fini);
976