xref: /openbmc/linux/drivers/w1/w1.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 
34 #include <asm/atomic.h>
35 
36 #include "w1.h"
37 #include "w1_io.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_SPINLOCK(w1_mlock);
58 LIST_HEAD(w1_masters);
59 
60 static pid_t control_thread;
61 static int control_needs_exit;
62 static DECLARE_COMPLETION(w1_control_complete);
63 
64 static int w1_master_match(struct device *dev, struct device_driver *drv)
65 {
66 	return 1;
67 }
68 
69 static int w1_master_probe(struct device *dev)
70 {
71 	return -ENODEV;
72 }
73 
74 static void w1_master_release(struct device *dev)
75 {
76 	struct w1_master *md = dev_to_w1_master(dev);
77 
78 	dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
79 
80 	dev_fini_netlink(md);
81 	memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
82 	kfree(md);
83 }
84 
85 static void w1_slave_release(struct device *dev)
86 {
87 	struct w1_slave *sl = dev_to_w1_slave(dev);
88 
89 	dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name);
90 
91 	while (atomic_read(&sl->refcnt)) {
92 		dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n",
93 				sl->name, atomic_read(&sl->refcnt));
94 		if (msleep_interruptible(1000))
95 			flush_signals(current);
96 	}
97 
98 	w1_family_put(sl->family);
99 	sl->master->slave_count--;
100 
101 	complete(&sl->released);
102 }
103 
104 static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
105 {
106 	struct w1_slave *sl = dev_to_w1_slave(dev);
107 
108 	return sprintf(buf, "%s\n", sl->name);
109 }
110 
111 static ssize_t w1_slave_read_id(struct kobject *kobj, char *buf, loff_t off, size_t count)
112 {
113 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
114 
115 	atomic_inc(&sl->refcnt);
116 	if (off > 8) {
117 		count = 0;
118 	} else {
119 		if (off + count > 8)
120 			count = 8 - off;
121 
122 		memcpy(buf, (u8 *)&sl->reg_num, count);
123 	}
124 	atomic_dec(&sl->refcnt);
125 
126 	return count;
127 }
128 
129 static struct device_attribute w1_slave_attr_name =
130 	__ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
131 
132 static struct bin_attribute w1_slave_attr_bin_id = {
133       .attr = {
134               .name = "id",
135               .mode = S_IRUGO,
136               .owner = THIS_MODULE,
137       },
138       .size = 8,
139       .read = w1_slave_read_id,
140 };
141 
142 /* Default family */
143 static struct w1_family w1_default_family;
144 
145 static int w1_hotplug(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size);
146 
147 static struct bus_type w1_bus_type = {
148 	.name = "w1",
149 	.match = w1_master_match,
150 	.hotplug = w1_hotplug,
151 };
152 
153 struct device_driver w1_master_driver = {
154 	.name = "w1_master_driver",
155 	.bus = &w1_bus_type,
156 	.probe = w1_master_probe,
157 };
158 
159 struct device w1_master_device = {
160 	.parent = NULL,
161 	.bus = &w1_bus_type,
162 	.bus_id = "w1 bus master",
163 	.driver = &w1_master_driver,
164 	.release = &w1_master_release
165 };
166 
167 struct device_driver w1_slave_driver = {
168 	.name = "w1_slave_driver",
169 	.bus = &w1_bus_type,
170 };
171 
172 struct device w1_slave_device = {
173 	.parent = NULL,
174 	.bus = &w1_bus_type,
175 	.bus_id = "w1 bus slave",
176 	.driver = &w1_slave_driver,
177 	.release = &w1_slave_release
178 };
179 
180 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
181 {
182 	struct w1_master *md = dev_to_w1_master(dev);
183 	ssize_t count;
184 
185 	if (down_interruptible (&md->mutex))
186 		return -EBUSY;
187 
188 	count = sprintf(buf, "%s\n", md->name);
189 
190 	up(&md->mutex);
191 
192 	return count;
193 }
194 
195 static ssize_t w1_master_attribute_store_search(struct device * dev,
196 						struct device_attribute *attr,
197 						const char * buf, size_t count)
198 {
199 	struct w1_master *md = dev_to_w1_master(dev);
200 
201 	if (down_interruptible (&md->mutex))
202 		return -EBUSY;
203 
204 	md->search_count = simple_strtol(buf, NULL, 0);
205 
206 	up(&md->mutex);
207 
208 	return count;
209 }
210 
211 static ssize_t w1_master_attribute_show_search(struct device *dev,
212 					       struct device_attribute *attr,
213 					       char *buf)
214 {
215 	struct w1_master *md = dev_to_w1_master(dev);
216 	ssize_t count;
217 
218 	if (down_interruptible (&md->mutex))
219 		return -EBUSY;
220 
221 	count = sprintf(buf, "%d\n", md->search_count);
222 
223 	up(&md->mutex);
224 
225 	return count;
226 }
227 
228 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
229 {
230 	struct w1_master *md = dev_to_w1_master(dev);
231 	ssize_t count;
232 
233 	if (down_interruptible(&md->mutex))
234 		return -EBUSY;
235 
236 	count = sprintf(buf, "0x%p\n", md->bus_master);
237 
238 	up(&md->mutex);
239 	return count;
240 }
241 
242 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
243 {
244 	ssize_t count;
245 	count = sprintf(buf, "%d\n", w1_timeout);
246 	return count;
247 }
248 
249 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
250 {
251 	struct w1_master *md = dev_to_w1_master(dev);
252 	ssize_t count;
253 
254 	if (down_interruptible(&md->mutex))
255 		return -EBUSY;
256 
257 	count = sprintf(buf, "%d\n", md->max_slave_count);
258 
259 	up(&md->mutex);
260 	return count;
261 }
262 
263 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
264 {
265 	struct w1_master *md = dev_to_w1_master(dev);
266 	ssize_t count;
267 
268 	if (down_interruptible(&md->mutex))
269 		return -EBUSY;
270 
271 	count = sprintf(buf, "%lu\n", md->attempts);
272 
273 	up(&md->mutex);
274 	return count;
275 }
276 
277 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
278 {
279 	struct w1_master *md = dev_to_w1_master(dev);
280 	ssize_t count;
281 
282 	if (down_interruptible(&md->mutex))
283 		return -EBUSY;
284 
285 	count = sprintf(buf, "%d\n", md->slave_count);
286 
287 	up(&md->mutex);
288 	return count;
289 }
290 
291 static ssize_t w1_master_attribute_show_slaves(struct device *dev, struct device_attribute *attr, char *buf)
292 {
293 	struct w1_master *md = dev_to_w1_master(dev);
294 	int c = PAGE_SIZE;
295 
296 	if (down_interruptible(&md->mutex))
297 		return -EBUSY;
298 
299 	if (md->slave_count == 0)
300 		c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
301 	else {
302 		struct list_head *ent, *n;
303 		struct w1_slave *sl;
304 
305 		list_for_each_safe(ent, n, &md->slist) {
306 			sl = list_entry(ent, struct w1_slave, w1_slave_entry);
307 
308 			c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
309 		}
310 	}
311 
312 	up(&md->mutex);
313 
314 	return PAGE_SIZE - c;
315 }
316 
317 #define W1_MASTER_ATTR_RO(_name, _mode)				\
318 	struct device_attribute w1_master_attribute_##_name =	\
319 		__ATTR(w1_master_##_name, _mode,		\
320 		       w1_master_attribute_show_##_name, NULL)
321 
322 #define W1_MASTER_ATTR_RW(_name, _mode)				\
323 	struct device_attribute w1_master_attribute_##_name =	\
324 		__ATTR(w1_master_##_name, _mode,		\
325 		       w1_master_attribute_show_##_name,	\
326 		       w1_master_attribute_store_##_name)
327 
328 static W1_MASTER_ATTR_RO(name, S_IRUGO);
329 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
330 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
331 static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
332 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
333 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
334 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
335 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
336 
337 static struct attribute *w1_master_default_attrs[] = {
338 	&w1_master_attribute_name.attr,
339 	&w1_master_attribute_slaves.attr,
340 	&w1_master_attribute_slave_count.attr,
341 	&w1_master_attribute_max_slave_count.attr,
342 	&w1_master_attribute_attempts.attr,
343 	&w1_master_attribute_timeout.attr,
344 	&w1_master_attribute_pointer.attr,
345 	&w1_master_attribute_search.attr,
346 	NULL
347 };
348 
349 static struct attribute_group w1_master_defattr_group = {
350 	.attrs = w1_master_default_attrs,
351 };
352 
353 int w1_create_master_attributes(struct w1_master *master)
354 {
355 	return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
356 }
357 
358 void w1_destroy_master_attributes(struct w1_master *master)
359 {
360 	sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
361 }
362 
363 #ifdef CONFIG_HOTPLUG
364 static int w1_hotplug(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
365 {
366 	struct w1_master *md = NULL;
367 	struct w1_slave *sl = NULL;
368 	char *event_owner, *name;
369 	int err, cur_index=0, cur_len=0;
370 
371 	if (dev->driver == &w1_master_driver) {
372 		md = container_of(dev, struct w1_master, dev);
373 		event_owner = "master";
374 		name = md->name;
375 	} else if (dev->driver == &w1_slave_driver) {
376 		sl = container_of(dev, struct w1_slave, dev);
377 		event_owner = "slave";
378 		name = sl->name;
379 	} else {
380 		dev_dbg(dev, "Unknown hotplug event.\n");
381 		return -EINVAL;
382 	}
383 
384 	dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n", event_owner, name, dev->bus_id);
385 
386 	if (dev->driver != &w1_slave_driver || !sl)
387 		return 0;
388 
389 	err = add_hotplug_env_var(envp, num_envp, &cur_index, buffer, buffer_size, &cur_len, "W1_FID=%02X", sl->reg_num.family);
390 	if (err)
391 		return err;
392 
393 	err = add_hotplug_env_var(envp, num_envp, &cur_index, buffer, buffer_size, &cur_len, "W1_SLAVE_ID=%024LX", (u64)sl->reg_num.id);
394 	if (err)
395 		return err;
396 
397 	return 0;
398 };
399 #else
400 static int w1_hotplug(struct device *dev, char **envp, int num_envp, char *buffer, int buffer_size)
401 {
402 	return 0;
403 }
404 #endif
405 
406 static int __w1_attach_slave_device(struct w1_slave *sl)
407 {
408 	int err;
409 
410 	sl->dev.parent = &sl->master->dev;
411 	sl->dev.driver = &w1_slave_driver;
412 	sl->dev.bus = &w1_bus_type;
413 	sl->dev.release = &w1_slave_release;
414 
415 	snprintf(&sl->dev.bus_id[0], sizeof(sl->dev.bus_id),
416 		 "%02x-%012llx",
417 		 (unsigned int) sl->reg_num.family,
418 		 (unsigned long long) sl->reg_num.id);
419 	snprintf(&sl->name[0], sizeof(sl->name),
420 		 "%02x-%012llx",
421 		 (unsigned int) sl->reg_num.family,
422 		 (unsigned long long) sl->reg_num.id);
423 
424 	dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__, &sl->dev.bus_id[0]);
425 
426 	err = device_register(&sl->dev);
427 	if (err < 0) {
428 		dev_err(&sl->dev,
429 			"Device registration [%s] failed. err=%d\n",
430 			sl->dev.bus_id, err);
431 		return err;
432 	}
433 
434 	/* Create "name" entry */
435 	err = device_create_file(&sl->dev, &w1_slave_attr_name);
436 	if (err < 0) {
437 		dev_err(&sl->dev,
438 			"sysfs file creation for [%s] failed. err=%d\n",
439 			sl->dev.bus_id, err);
440 		goto out_unreg;
441 	}
442 
443 	/* Create "id" entry */
444 	err = sysfs_create_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
445 	if (err < 0) {
446 		dev_err(&sl->dev,
447 			"sysfs file creation for [%s] failed. err=%d\n",
448 			sl->dev.bus_id, err);
449 		goto out_rem1;
450 	}
451 
452 	/* if the family driver needs to initialize something... */
453 	if (sl->family->fops && sl->family->fops->add_slave &&
454 	    ((err = sl->family->fops->add_slave(sl)) < 0)) {
455 		dev_err(&sl->dev,
456 			"sysfs file creation for [%s] failed. err=%d\n",
457 			sl->dev.bus_id, err);
458 		goto out_rem2;
459 	}
460 
461 	list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
462 
463 	return 0;
464 
465 out_rem2:
466 	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
467 out_rem1:
468 	device_remove_file(&sl->dev, &w1_slave_attr_name);
469 out_unreg:
470 	device_unregister(&sl->dev);
471 	return err;
472 }
473 
474 static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
475 {
476 	struct w1_slave *sl;
477 	struct w1_family *f;
478 	int err;
479 	struct w1_netlink_msg msg;
480 
481 	sl = kmalloc(sizeof(struct w1_slave), GFP_KERNEL);
482 	if (!sl) {
483 		dev_err(&dev->dev,
484 			 "%s: failed to allocate new slave device.\n",
485 			 __func__);
486 		return -ENOMEM;
487 	}
488 
489 	memset(sl, 0, sizeof(*sl));
490 
491 	sl->owner = THIS_MODULE;
492 	sl->master = dev;
493 	set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
494 
495 	memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
496 	atomic_set(&sl->refcnt, 0);
497 	init_completion(&sl->released);
498 
499 	spin_lock(&w1_flock);
500 	f = w1_family_registered(rn->family);
501 	if (!f) {
502 		f= &w1_default_family;
503 		dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
504 			  rn->family, rn->family,
505 			  (unsigned long long)rn->id, rn->crc);
506 	}
507 	__w1_family_get(f);
508 	spin_unlock(&w1_flock);
509 
510 	sl->family = f;
511 
512 
513 	err = __w1_attach_slave_device(sl);
514 	if (err < 0) {
515 		dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
516 			 sl->name);
517 		w1_family_put(sl->family);
518 		kfree(sl);
519 		return err;
520 	}
521 
522 	sl->ttl = dev->slave_ttl;
523 	dev->slave_count++;
524 
525 	memcpy(&msg.id.id, rn, sizeof(msg.id.id));
526 	msg.type = W1_SLAVE_ADD;
527 	w1_netlink_send(dev, &msg);
528 
529 	return 0;
530 }
531 
532 static void w1_slave_detach(struct w1_slave *sl)
533 {
534 	struct w1_netlink_msg msg;
535 
536 	dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);
537 
538 	list_del(&sl->w1_slave_entry);
539 
540 	if (sl->family->fops && sl->family->fops->remove_slave)
541 		sl->family->fops->remove_slave(sl);
542 
543 	memcpy(&msg.id.id, &sl->reg_num, sizeof(msg.id.id));
544 	msg.type = W1_SLAVE_REMOVE;
545 	w1_netlink_send(sl->master, &msg);
546 
547 	sysfs_remove_bin_file(&sl->dev.kobj, &w1_slave_attr_bin_id);
548 	device_remove_file(&sl->dev, &w1_slave_attr_name);
549 	device_unregister(&sl->dev);
550 
551 	wait_for_completion(&sl->released);
552 	kfree(sl);
553 }
554 
555 static struct w1_master *w1_search_master(unsigned long data)
556 {
557 	struct w1_master *dev;
558 	int found = 0;
559 
560 	spin_lock_bh(&w1_mlock);
561 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
562 		if (dev->bus_master->data == data) {
563 			found = 1;
564 			atomic_inc(&dev->refcnt);
565 			break;
566 		}
567 	}
568 	spin_unlock_bh(&w1_mlock);
569 
570 	return (found)?dev:NULL;
571 }
572 
573 void w1_reconnect_slaves(struct w1_family *f)
574 {
575 	struct w1_master *dev;
576 
577 	spin_lock_bh(&w1_mlock);
578 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
579 		dev_dbg(&dev->dev, "Reconnecting slaves in %s into new family %02x.\n",
580 				dev->name, f->fid);
581 		set_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
582 	}
583 	spin_unlock_bh(&w1_mlock);
584 }
585 
586 static void w1_slave_found(unsigned long data, u64 rn)
587 {
588 	int slave_count;
589 	struct w1_slave *sl;
590 	struct list_head *ent;
591 	struct w1_reg_num *tmp;
592 	int family_found = 0;
593 	struct w1_master *dev;
594 	u64 rn_le = cpu_to_le64(rn);
595 
596 	dev = w1_search_master(data);
597 	if (!dev) {
598 		printk(KERN_ERR "Failed to find w1 master device for data %08lx, it is impossible.\n",
599 				data);
600 		return;
601 	}
602 
603 	tmp = (struct w1_reg_num *) &rn;
604 
605 	slave_count = 0;
606 	list_for_each(ent, &dev->slist) {
607 
608 		sl = list_entry(ent, struct w1_slave, w1_slave_entry);
609 
610 		if (sl->reg_num.family == tmp->family &&
611 		    sl->reg_num.id == tmp->id &&
612 		    sl->reg_num.crc == tmp->crc) {
613 			set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
614 			break;
615 		} else if (sl->reg_num.family == tmp->family) {
616 			family_found = 1;
617 			break;
618 		}
619 
620 		slave_count++;
621 	}
622 
623 	if (slave_count == dev->slave_count &&
624 		rn && ((rn >> 56) & 0xff) == w1_calc_crc8((u8 *)&rn_le, 7)) {
625 		w1_attach_slave_device(dev, tmp);
626 	}
627 
628 	atomic_dec(&dev->refcnt);
629 }
630 
631 /**
632  * Performs a ROM Search & registers any devices found.
633  * The 1-wire search is a simple binary tree search.
634  * For each bit of the address, we read two bits and write one bit.
635  * The bit written will put to sleep all devies that don't match that bit.
636  * When the two reads differ, the direction choice is obvious.
637  * When both bits are 0, we must choose a path to take.
638  * When we can scan all 64 bits without having to choose a path, we are done.
639  *
640  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
641  *
642  * @dev        The master device to search
643  * @cb         Function to call when a device is found
644  */
645 void w1_search(struct w1_master *dev, w1_slave_found_callback cb)
646 {
647 	u64 last_rn, rn, tmp64;
648 	int i, slave_count = 0;
649 	int last_zero, last_device;
650 	int search_bit, desc_bit;
651 	u8  triplet_ret = 0;
652 
653 	search_bit = 0;
654 	rn = last_rn = 0;
655 	last_device = 0;
656 	last_zero = -1;
657 
658 	desc_bit = 64;
659 
660 	while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
661 		last_rn = rn;
662 		rn = 0;
663 
664 		/*
665 		 * Reset bus and all 1-wire device state machines
666 		 * so they can respond to our requests.
667 		 *
668 		 * Return 0 - device(s) present, 1 - no devices present.
669 		 */
670 		if (w1_reset_bus(dev)) {
671 			dev_dbg(&dev->dev, "No devices present on the wire.\n");
672 			break;
673 		}
674 
675 		/* Start the search */
676 		w1_write_8(dev, W1_SEARCH);
677 		for (i = 0; i < 64; ++i) {
678 			/* Determine the direction/search bit */
679 			if (i == desc_bit)
680 				search_bit = 1;	  /* took the 0 path last time, so take the 1 path */
681 			else if (i > desc_bit)
682 				search_bit = 0;	  /* take the 0 path on the next branch */
683 			else
684 				search_bit = ((last_rn >> i) & 0x1);
685 
686 			/** Read two bits and write one bit */
687 			triplet_ret = w1_triplet(dev, search_bit);
688 
689 			/* quit if no device responded */
690 			if ( (triplet_ret & 0x03) == 0x03 )
691 				break;
692 
693 			/* If both directions were valid, and we took the 0 path... */
694 			if (triplet_ret == 0)
695 				last_zero = i;
696 
697 			/* extract the direction taken & update the device number */
698 			tmp64 = (triplet_ret >> 2);
699 			rn |= (tmp64 << i);
700 		}
701 
702 		if ( (triplet_ret & 0x03) != 0x03 ) {
703 			if ( (desc_bit == last_zero) || (last_zero < 0))
704 				last_device = 1;
705 			desc_bit = last_zero;
706 			cb(dev->bus_master->data, rn);
707 		}
708 	}
709 }
710 
711 static int w1_control(void *data)
712 {
713 	struct w1_slave *sl, *sln;
714 	struct w1_master *dev, *n;
715 	int err, have_to_wait = 0;
716 
717 	daemonize("w1_control");
718 	allow_signal(SIGTERM);
719 
720 	while (!control_needs_exit || have_to_wait) {
721 		have_to_wait = 0;
722 
723 		try_to_freeze();
724 		msleep_interruptible(w1_control_timeout * 1000);
725 
726 		if (signal_pending(current))
727 			flush_signals(current);
728 
729 		list_for_each_entry_safe(dev, n, &w1_masters, w1_master_entry) {
730 			if (!control_needs_exit && !dev->flags)
731 				continue;
732 			/*
733 			 * Little race: we can create thread but not set the flag.
734 			 * Get a chance for external process to set flag up.
735 			 */
736 			if (!dev->initialized) {
737 				have_to_wait = 1;
738 				continue;
739 			}
740 
741 			if (control_needs_exit) {
742 				set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
743 
744 				err = kill_proc(dev->kpid, SIGTERM, 1);
745 				if (err)
746 					dev_err(&dev->dev,
747 						 "Failed to send signal to w1 kernel thread %d.\n",
748 						 dev->kpid);
749 			}
750 
751 			if (test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
752 				wait_for_completion(&dev->dev_exited);
753 				spin_lock_bh(&w1_mlock);
754 				list_del(&dev->w1_master_entry);
755 				spin_unlock_bh(&w1_mlock);
756 
757 				down(&dev->mutex);
758 				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
759 					w1_slave_detach(sl);
760 				}
761 				w1_destroy_master_attributes(dev);
762 				up(&dev->mutex);
763 				atomic_dec(&dev->refcnt);
764 				continue;
765 			}
766 
767 			if (test_bit(W1_MASTER_NEED_RECONNECT, &dev->flags)) {
768 				dev_dbg(&dev->dev, "Reconnecting slaves in device %s.\n", dev->name);
769 				down(&dev->mutex);
770 				list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
771 					if (sl->family->fid == W1_FAMILY_DEFAULT) {
772 						struct w1_reg_num rn;
773 
774 						memcpy(&rn, &sl->reg_num, sizeof(rn));
775 						w1_slave_detach(sl);
776 
777 						w1_attach_slave_device(dev, &rn);
778 					}
779 				}
780 				dev_dbg(&dev->dev, "Reconnecting slaves in device %s has been finished.\n", dev->name);
781 				clear_bit(W1_MASTER_NEED_RECONNECT, &dev->flags);
782 				up(&dev->mutex);
783 			}
784 		}
785 	}
786 
787 	complete_and_exit(&w1_control_complete, 0);
788 }
789 
790 int w1_process(void *data)
791 {
792 	struct w1_master *dev = (struct w1_master *) data;
793 	struct w1_slave *sl, *sln;
794 
795 	daemonize("%s", dev->name);
796 	allow_signal(SIGTERM);
797 
798 	while (!test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
799 		try_to_freeze();
800 		msleep_interruptible(w1_timeout * 1000);
801 
802 		if (signal_pending(current))
803 			flush_signals(current);
804 
805 		if (test_bit(W1_MASTER_NEED_EXIT, &dev->flags))
806 			break;
807 
808 		if (!dev->initialized)
809 			continue;
810 
811 		if (dev->search_count == 0)
812 			continue;
813 
814 		if (down_interruptible(&dev->mutex))
815 			continue;
816 
817 		list_for_each_entry(sl, &dev->slist, w1_slave_entry)
818 			clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
819 
820 		w1_search_devices(dev, w1_slave_found);
821 
822 		list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
823 			if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl) {
824 				w1_slave_detach(sl);
825 
826 				dev->slave_count--;
827 			} else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
828 				sl->ttl = dev->slave_ttl;
829 		}
830 
831 		if (dev->search_count > 0)
832 			dev->search_count--;
833 
834 		up(&dev->mutex);
835 	}
836 
837 	atomic_dec(&dev->refcnt);
838 	complete_and_exit(&dev->dev_exited, 0);
839 
840 	return 0;
841 }
842 
843 static int w1_init(void)
844 {
845 	int retval;
846 
847 	printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");
848 
849 	retval = bus_register(&w1_bus_type);
850 	if (retval) {
851 		printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
852 		goto err_out_exit_init;
853 	}
854 
855 	retval = driver_register(&w1_master_driver);
856 	if (retval) {
857 		printk(KERN_ERR
858 			"Failed to register master driver. err=%d.\n",
859 			retval);
860 		goto err_out_bus_unregister;
861 	}
862 
863 	retval = driver_register(&w1_slave_driver);
864 	if (retval) {
865 		printk(KERN_ERR
866 			"Failed to register master driver. err=%d.\n",
867 			retval);
868 		goto err_out_master_unregister;
869 	}
870 
871 	control_thread = kernel_thread(&w1_control, NULL, 0);
872 	if (control_thread < 0) {
873 		printk(KERN_ERR "Failed to create control thread. err=%d\n",
874 			control_thread);
875 		retval = control_thread;
876 		goto err_out_slave_unregister;
877 	}
878 
879 	return 0;
880 
881 err_out_slave_unregister:
882 	driver_unregister(&w1_slave_driver);
883 
884 err_out_master_unregister:
885 	driver_unregister(&w1_master_driver);
886 
887 err_out_bus_unregister:
888 	bus_unregister(&w1_bus_type);
889 
890 err_out_exit_init:
891 	return retval;
892 }
893 
894 static void w1_fini(void)
895 {
896 	struct w1_master *dev;
897 
898 	list_for_each_entry(dev, &w1_masters, w1_master_entry)
899 		__w1_remove_master_device(dev);
900 
901 	control_needs_exit = 1;
902 	wait_for_completion(&w1_control_complete);
903 
904 	driver_unregister(&w1_slave_driver);
905 	driver_unregister(&w1_master_driver);
906 	bus_unregister(&w1_bus_type);
907 }
908 
909 module_init(w1_init);
910 module_exit(w1_fini);
911