xref: /openbmc/linux/drivers/w1/w1.c (revision a36954f5)
1 /*
2  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  */
14 
15 #include <linux/delay.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/moduleparam.h>
19 #include <linux/list.h>
20 #include <linux/interrupt.h>
21 #include <linux/spinlock.h>
22 #include <linux/timer.h>
23 #include <linux/device.h>
24 #include <linux/slab.h>
25 #include <linux/sched.h>
26 #include <linux/kthread.h>
27 #include <linux/freezer.h>
28 
29 #include <linux/atomic.h>
30 
31 #include "w1.h"
32 #include "w1_int.h"
33 #include "w1_family.h"
34 #include "w1_netlink.h"
35 
36 static int w1_timeout = 10;
37 module_param_named(timeout, w1_timeout, int, 0);
38 MODULE_PARM_DESC(timeout, "time in seconds between automatic slave searches");
39 
40 static int w1_timeout_us = 0;
41 module_param_named(timeout_us, w1_timeout_us, int, 0);
42 MODULE_PARM_DESC(timeout_us,
43 		 "time in microseconds between automatic slave searches");
44 
45 /* A search stops when w1_max_slave_count devices have been found in that
46  * search.  The next search will start over and detect the same set of devices
47  * on a static 1-wire bus.  Memory is not allocated based on this number, just
48  * on the number of devices known to the kernel.  Having a high number does not
49  * consume additional resources.  As a special case, if there is only one
50  * device on the network and w1_max_slave_count is set to 1, the device id can
51  * be read directly skipping the normal slower search process.
52  */
53 int w1_max_slave_count = 64;
54 module_param_named(max_slave_count, w1_max_slave_count, int, 0);
55 MODULE_PARM_DESC(max_slave_count,
56 	"maximum number of slaves detected in a search");
57 
58 int w1_max_slave_ttl = 10;
59 module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);
60 MODULE_PARM_DESC(slave_ttl,
61 	"Number of searches not seeing a slave before it will be removed");
62 
63 DEFINE_MUTEX(w1_mlock);
64 LIST_HEAD(w1_masters);
65 
66 static int w1_master_match(struct device *dev, struct device_driver *drv)
67 {
68 	return 1;
69 }
70 
71 static int w1_master_probe(struct device *dev)
72 {
73 	return -ENODEV;
74 }
75 
76 static void w1_master_release(struct device *dev)
77 {
78 	struct w1_master *md = dev_to_w1_master(dev);
79 
80 	dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
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 [%p]\n", __func__, sl->name, sl);
90 
91 	w1_family_put(sl->family);
92 	sl->master->slave_count--;
93 }
94 
95 static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf)
96 {
97 	struct w1_slave *sl = dev_to_w1_slave(dev);
98 
99 	return sprintf(buf, "%s\n", sl->name);
100 }
101 static DEVICE_ATTR_RO(name);
102 
103 static ssize_t id_show(struct device *dev,
104 	struct device_attribute *attr, char *buf)
105 {
106 	struct w1_slave *sl = dev_to_w1_slave(dev);
107 	ssize_t count = sizeof(sl->reg_num);
108 
109 	memcpy(buf, (u8 *)&sl->reg_num, count);
110 	return count;
111 }
112 static DEVICE_ATTR_RO(id);
113 
114 static struct attribute *w1_slave_attrs[] = {
115 	&dev_attr_name.attr,
116 	&dev_attr_id.attr,
117 	NULL,
118 };
119 ATTRIBUTE_GROUPS(w1_slave);
120 
121 /* Default family */
122 
123 static ssize_t rw_write(struct file *filp, struct kobject *kobj,
124 			struct bin_attribute *bin_attr, char *buf, loff_t off,
125 			size_t count)
126 {
127 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
128 
129 	mutex_lock(&sl->master->mutex);
130 	if (w1_reset_select_slave(sl)) {
131 		count = 0;
132 		goto out_up;
133 	}
134 
135 	w1_write_block(sl->master, buf, count);
136 
137 out_up:
138 	mutex_unlock(&sl->master->mutex);
139 	return count;
140 }
141 
142 static ssize_t rw_read(struct file *filp, struct kobject *kobj,
143 		       struct bin_attribute *bin_attr, char *buf, loff_t off,
144 		       size_t count)
145 {
146 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
147 
148 	mutex_lock(&sl->master->mutex);
149 	w1_read_block(sl->master, buf, count);
150 	mutex_unlock(&sl->master->mutex);
151 	return count;
152 }
153 
154 static BIN_ATTR_RW(rw, PAGE_SIZE);
155 
156 static struct bin_attribute *w1_slave_bin_attrs[] = {
157 	&bin_attr_rw,
158 	NULL,
159 };
160 
161 static const struct attribute_group w1_slave_default_group = {
162 	.bin_attrs = w1_slave_bin_attrs,
163 };
164 
165 static const struct attribute_group *w1_slave_default_groups[] = {
166 	&w1_slave_default_group,
167 	NULL,
168 };
169 
170 static struct w1_family_ops w1_default_fops = {
171 	.groups		= w1_slave_default_groups,
172 };
173 
174 static struct w1_family w1_default_family = {
175 	.fops = &w1_default_fops,
176 };
177 
178 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env);
179 
180 static struct bus_type w1_bus_type = {
181 	.name = "w1",
182 	.match = w1_master_match,
183 	.uevent = w1_uevent,
184 };
185 
186 struct device_driver w1_master_driver = {
187 	.name = "w1_master_driver",
188 	.bus = &w1_bus_type,
189 	.probe = w1_master_probe,
190 };
191 
192 struct device w1_master_device = {
193 	.parent = NULL,
194 	.bus = &w1_bus_type,
195 	.init_name = "w1 bus master",
196 	.driver = &w1_master_driver,
197 	.release = &w1_master_release
198 };
199 
200 static struct device_driver w1_slave_driver = {
201 	.name = "w1_slave_driver",
202 	.bus = &w1_bus_type,
203 };
204 
205 #if 0
206 struct device w1_slave_device = {
207 	.parent = NULL,
208 	.bus = &w1_bus_type,
209 	.init_name = "w1 bus slave",
210 	.driver = &w1_slave_driver,
211 	.release = &w1_slave_release
212 };
213 #endif  /*  0  */
214 
215 static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
216 {
217 	struct w1_master *md = dev_to_w1_master(dev);
218 	ssize_t count;
219 
220 	mutex_lock(&md->mutex);
221 	count = sprintf(buf, "%s\n", md->name);
222 	mutex_unlock(&md->mutex);
223 
224 	return count;
225 }
226 
227 static ssize_t w1_master_attribute_store_search(struct device * dev,
228 						struct device_attribute *attr,
229 						const char * buf, size_t count)
230 {
231 	long tmp;
232 	struct w1_master *md = dev_to_w1_master(dev);
233 	int ret;
234 
235 	ret = kstrtol(buf, 0, &tmp);
236 	if (ret)
237 		return ret;
238 
239 	mutex_lock(&md->mutex);
240 	md->search_count = tmp;
241 	mutex_unlock(&md->mutex);
242 	/* Only wake if it is going to be searching. */
243 	if (tmp)
244 		wake_up_process(md->thread);
245 
246 	return count;
247 }
248 
249 static ssize_t w1_master_attribute_show_search(struct device *dev,
250 					       struct device_attribute *attr,
251 					       char *buf)
252 {
253 	struct w1_master *md = dev_to_w1_master(dev);
254 	ssize_t count;
255 
256 	mutex_lock(&md->mutex);
257 	count = sprintf(buf, "%d\n", md->search_count);
258 	mutex_unlock(&md->mutex);
259 
260 	return count;
261 }
262 
263 static ssize_t w1_master_attribute_store_pullup(struct device *dev,
264 						struct device_attribute *attr,
265 						const char *buf, size_t count)
266 {
267 	long tmp;
268 	struct w1_master *md = dev_to_w1_master(dev);
269 	int ret;
270 
271 	ret = kstrtol(buf, 0, &tmp);
272 	if (ret)
273 		return ret;
274 
275 	mutex_lock(&md->mutex);
276 	md->enable_pullup = tmp;
277 	mutex_unlock(&md->mutex);
278 
279 	return count;
280 }
281 
282 static ssize_t w1_master_attribute_show_pullup(struct device *dev,
283 					       struct device_attribute *attr,
284 					       char *buf)
285 {
286 	struct w1_master *md = dev_to_w1_master(dev);
287 	ssize_t count;
288 
289 	mutex_lock(&md->mutex);
290 	count = sprintf(buf, "%d\n", md->enable_pullup);
291 	mutex_unlock(&md->mutex);
292 
293 	return count;
294 }
295 
296 static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
297 {
298 	struct w1_master *md = dev_to_w1_master(dev);
299 	ssize_t count;
300 
301 	mutex_lock(&md->mutex);
302 	count = sprintf(buf, "0x%p\n", md->bus_master);
303 	mutex_unlock(&md->mutex);
304 	return count;
305 }
306 
307 static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
308 {
309 	ssize_t count;
310 	count = sprintf(buf, "%d\n", w1_timeout);
311 	return count;
312 }
313 
314 static ssize_t w1_master_attribute_show_timeout_us(struct device *dev,
315 	struct device_attribute *attr, char *buf)
316 {
317 	ssize_t count;
318 	count = sprintf(buf, "%d\n", w1_timeout_us);
319 	return count;
320 }
321 
322 static ssize_t w1_master_attribute_store_max_slave_count(struct device *dev,
323 	struct device_attribute *attr, const char *buf, size_t count)
324 {
325 	int tmp;
326 	struct w1_master *md = dev_to_w1_master(dev);
327 
328 	if (kstrtoint(buf, 0, &tmp) || tmp < 1)
329 		return -EINVAL;
330 
331 	mutex_lock(&md->mutex);
332 	md->max_slave_count = tmp;
333 	/* allow each time the max_slave_count is updated */
334 	clear_bit(W1_WARN_MAX_COUNT, &md->flags);
335 	mutex_unlock(&md->mutex);
336 
337 	return count;
338 }
339 
340 static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
341 {
342 	struct w1_master *md = dev_to_w1_master(dev);
343 	ssize_t count;
344 
345 	mutex_lock(&md->mutex);
346 	count = sprintf(buf, "%d\n", md->max_slave_count);
347 	mutex_unlock(&md->mutex);
348 	return count;
349 }
350 
351 static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
352 {
353 	struct w1_master *md = dev_to_w1_master(dev);
354 	ssize_t count;
355 
356 	mutex_lock(&md->mutex);
357 	count = sprintf(buf, "%lu\n", md->attempts);
358 	mutex_unlock(&md->mutex);
359 	return count;
360 }
361 
362 static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
363 {
364 	struct w1_master *md = dev_to_w1_master(dev);
365 	ssize_t count;
366 
367 	mutex_lock(&md->mutex);
368 	count = sprintf(buf, "%d\n", md->slave_count);
369 	mutex_unlock(&md->mutex);
370 	return count;
371 }
372 
373 static ssize_t w1_master_attribute_show_slaves(struct device *dev,
374 	struct device_attribute *attr, char *buf)
375 {
376 	struct w1_master *md = dev_to_w1_master(dev);
377 	int c = PAGE_SIZE;
378 	struct list_head *ent, *n;
379 	struct w1_slave *sl = NULL;
380 
381 	mutex_lock(&md->list_mutex);
382 
383 	list_for_each_safe(ent, n, &md->slist) {
384 		sl = list_entry(ent, struct w1_slave, w1_slave_entry);
385 
386 		c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
387 	}
388 	if (!sl)
389 		c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
390 
391 	mutex_unlock(&md->list_mutex);
392 
393 	return PAGE_SIZE - c;
394 }
395 
396 static ssize_t w1_master_attribute_show_add(struct device *dev,
397 	struct device_attribute *attr, char *buf)
398 {
399 	int c = PAGE_SIZE;
400 	c -= snprintf(buf+PAGE_SIZE - c, c,
401 		"write device id xx-xxxxxxxxxxxx to add slave\n");
402 	return PAGE_SIZE - c;
403 }
404 
405 static int w1_atoreg_num(struct device *dev, const char *buf, size_t count,
406 	struct w1_reg_num *rn)
407 {
408 	unsigned int family;
409 	unsigned long long id;
410 	int i;
411 	u64 rn64_le;
412 
413 	/* The CRC value isn't read from the user because the sysfs directory
414 	 * doesn't include it and most messages from the bus search don't
415 	 * print it either.  It would be unreasonable for the user to then
416 	 * provide it.
417 	 */
418 	const char *error_msg = "bad slave string format, expecting "
419 		"ff-dddddddddddd\n";
420 
421 	if (buf[2] != '-') {
422 		dev_err(dev, "%s", error_msg);
423 		return -EINVAL;
424 	}
425 	i = sscanf(buf, "%02x-%012llx", &family, &id);
426 	if (i != 2) {
427 		dev_err(dev, "%s", error_msg);
428 		return -EINVAL;
429 	}
430 	rn->family = family;
431 	rn->id = id;
432 
433 	rn64_le = cpu_to_le64(*(u64 *)rn);
434 	rn->crc = w1_calc_crc8((u8 *)&rn64_le, 7);
435 
436 #if 0
437 	dev_info(dev, "With CRC device is %02x.%012llx.%02x.\n",
438 		  rn->family, (unsigned long long)rn->id, rn->crc);
439 #endif
440 
441 	return 0;
442 }
443 
444 /* Searches the slaves in the w1_master and returns a pointer or NULL.
445  * Note: must not hold list_mutex
446  */
447 struct w1_slave *w1_slave_search_device(struct w1_master *dev,
448 	struct w1_reg_num *rn)
449 {
450 	struct w1_slave *sl;
451 	mutex_lock(&dev->list_mutex);
452 	list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
453 		if (sl->reg_num.family == rn->family &&
454 				sl->reg_num.id == rn->id &&
455 				sl->reg_num.crc == rn->crc) {
456 			mutex_unlock(&dev->list_mutex);
457 			return sl;
458 		}
459 	}
460 	mutex_unlock(&dev->list_mutex);
461 	return NULL;
462 }
463 
464 static ssize_t w1_master_attribute_store_add(struct device *dev,
465 						struct device_attribute *attr,
466 						const char *buf, size_t count)
467 {
468 	struct w1_master *md = dev_to_w1_master(dev);
469 	struct w1_reg_num rn;
470 	struct w1_slave *sl;
471 	ssize_t result = count;
472 
473 	if (w1_atoreg_num(dev, buf, count, &rn))
474 		return -EINVAL;
475 
476 	mutex_lock(&md->mutex);
477 	sl = w1_slave_search_device(md, &rn);
478 	/* It would be nice to do a targeted search one the one-wire bus
479 	 * for the new device to see if it is out there or not.  But the
480 	 * current search doesn't support that.
481 	 */
482 	if (sl) {
483 		dev_info(dev, "Device %s already exists\n", sl->name);
484 		result = -EINVAL;
485 	} else {
486 		w1_attach_slave_device(md, &rn);
487 	}
488 	mutex_unlock(&md->mutex);
489 
490 	return result;
491 }
492 
493 static ssize_t w1_master_attribute_show_remove(struct device *dev,
494 	struct device_attribute *attr, char *buf)
495 {
496 	int c = PAGE_SIZE;
497 	c -= snprintf(buf+PAGE_SIZE - c, c,
498 		"write device id xx-xxxxxxxxxxxx to remove slave\n");
499 	return PAGE_SIZE - c;
500 }
501 
502 static ssize_t w1_master_attribute_store_remove(struct device *dev,
503 						struct device_attribute *attr,
504 						const char *buf, size_t count)
505 {
506 	struct w1_master *md = dev_to_w1_master(dev);
507 	struct w1_reg_num rn;
508 	struct w1_slave *sl;
509 	ssize_t result = count;
510 
511 	if (w1_atoreg_num(dev, buf, count, &rn))
512 		return -EINVAL;
513 
514 	mutex_lock(&md->mutex);
515 	sl = w1_slave_search_device(md, &rn);
516 	if (sl) {
517 		result = w1_slave_detach(sl);
518 		/* refcnt 0 means it was detached in the call */
519 		if (result == 0)
520 			result = count;
521 	} else {
522 		dev_info(dev, "Device %02x-%012llx doesn't exists\n", rn.family,
523 			(unsigned long long)rn.id);
524 		result = -EINVAL;
525 	}
526 	mutex_unlock(&md->mutex);
527 
528 	return result;
529 }
530 
531 #define W1_MASTER_ATTR_RO(_name, _mode)				\
532 	struct device_attribute w1_master_attribute_##_name =	\
533 		__ATTR(w1_master_##_name, _mode,		\
534 		       w1_master_attribute_show_##_name, NULL)
535 
536 #define W1_MASTER_ATTR_RW(_name, _mode)				\
537 	struct device_attribute w1_master_attribute_##_name =	\
538 		__ATTR(w1_master_##_name, _mode,		\
539 		       w1_master_attribute_show_##_name,	\
540 		       w1_master_attribute_store_##_name)
541 
542 static W1_MASTER_ATTR_RO(name, S_IRUGO);
543 static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
544 static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
545 static W1_MASTER_ATTR_RW(max_slave_count, S_IRUGO | S_IWUSR | S_IWGRP);
546 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
547 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
548 static W1_MASTER_ATTR_RO(timeout_us, S_IRUGO);
549 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
550 static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUSR | S_IWGRP);
551 static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUSR | S_IWGRP);
552 static W1_MASTER_ATTR_RW(add, S_IRUGO | S_IWUSR | S_IWGRP);
553 static W1_MASTER_ATTR_RW(remove, S_IRUGO | S_IWUSR | S_IWGRP);
554 
555 static struct attribute *w1_master_default_attrs[] = {
556 	&w1_master_attribute_name.attr,
557 	&w1_master_attribute_slaves.attr,
558 	&w1_master_attribute_slave_count.attr,
559 	&w1_master_attribute_max_slave_count.attr,
560 	&w1_master_attribute_attempts.attr,
561 	&w1_master_attribute_timeout.attr,
562 	&w1_master_attribute_timeout_us.attr,
563 	&w1_master_attribute_pointer.attr,
564 	&w1_master_attribute_search.attr,
565 	&w1_master_attribute_pullup.attr,
566 	&w1_master_attribute_add.attr,
567 	&w1_master_attribute_remove.attr,
568 	NULL
569 };
570 
571 static struct attribute_group w1_master_defattr_group = {
572 	.attrs = w1_master_default_attrs,
573 };
574 
575 int w1_create_master_attributes(struct w1_master *master)
576 {
577 	return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
578 }
579 
580 void w1_destroy_master_attributes(struct w1_master *master)
581 {
582 	sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
583 }
584 
585 static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
586 {
587 	struct w1_master *md = NULL;
588 	struct w1_slave *sl = NULL;
589 	char *event_owner, *name;
590 	int err = 0;
591 
592 	if (dev->driver == &w1_master_driver) {
593 		md = container_of(dev, struct w1_master, dev);
594 		event_owner = "master";
595 		name = md->name;
596 	} else if (dev->driver == &w1_slave_driver) {
597 		sl = container_of(dev, struct w1_slave, dev);
598 		event_owner = "slave";
599 		name = sl->name;
600 	} else {
601 		dev_dbg(dev, "Unknown event.\n");
602 		return -EINVAL;
603 	}
604 
605 	dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
606 			event_owner, name, dev_name(dev));
607 
608 	if (dev->driver != &w1_slave_driver || !sl)
609 		goto end;
610 
611 	err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
612 	if (err)
613 		goto end;
614 
615 	err = add_uevent_var(env, "W1_SLAVE_ID=%024LX",
616 			     (unsigned long long)sl->reg_num.id);
617 end:
618 	return err;
619 }
620 
621 static int w1_family_notify(unsigned long action, struct w1_slave *sl)
622 {
623 	struct w1_family_ops *fops;
624 	int err;
625 
626 	fops = sl->family->fops;
627 
628 	if (!fops)
629 		return 0;
630 
631 	switch (action) {
632 	case BUS_NOTIFY_ADD_DEVICE:
633 		/* if the family driver needs to initialize something... */
634 		if (fops->add_slave) {
635 			err = fops->add_slave(sl);
636 			if (err < 0) {
637 				dev_err(&sl->dev,
638 					"add_slave() call failed. err=%d\n",
639 					err);
640 				return err;
641 			}
642 		}
643 		if (fops->groups) {
644 			err = sysfs_create_groups(&sl->dev.kobj, fops->groups);
645 			if (err) {
646 				dev_err(&sl->dev,
647 					"sysfs group creation failed. err=%d\n",
648 					err);
649 				return err;
650 			}
651 		}
652 
653 		break;
654 	case BUS_NOTIFY_DEL_DEVICE:
655 		if (fops->remove_slave)
656 			sl->family->fops->remove_slave(sl);
657 		if (fops->groups)
658 			sysfs_remove_groups(&sl->dev.kobj, fops->groups);
659 		break;
660 	}
661 	return 0;
662 }
663 
664 static int __w1_attach_slave_device(struct w1_slave *sl)
665 {
666 	int err;
667 
668 	sl->dev.parent = &sl->master->dev;
669 	sl->dev.driver = &w1_slave_driver;
670 	sl->dev.bus = &w1_bus_type;
671 	sl->dev.release = &w1_slave_release;
672 	sl->dev.groups = w1_slave_groups;
673 
674 	dev_set_name(&sl->dev, "%02x-%012llx",
675 		 (unsigned int) sl->reg_num.family,
676 		 (unsigned long long) sl->reg_num.id);
677 	snprintf(&sl->name[0], sizeof(sl->name),
678 		 "%02x-%012llx",
679 		 (unsigned int) sl->reg_num.family,
680 		 (unsigned long long) sl->reg_num.id);
681 
682 	dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
683 		dev_name(&sl->dev), sl);
684 
685 	/* suppress for w1_family_notify before sending KOBJ_ADD */
686 	dev_set_uevent_suppress(&sl->dev, true);
687 
688 	err = device_register(&sl->dev);
689 	if (err < 0) {
690 		dev_err(&sl->dev,
691 			"Device registration [%s] failed. err=%d\n",
692 			dev_name(&sl->dev), err);
693 		return err;
694 	}
695 	w1_family_notify(BUS_NOTIFY_ADD_DEVICE, sl);
696 
697 	dev_set_uevent_suppress(&sl->dev, false);
698 	kobject_uevent(&sl->dev.kobj, KOBJ_ADD);
699 
700 	mutex_lock(&sl->master->list_mutex);
701 	list_add_tail(&sl->w1_slave_entry, &sl->master->slist);
702 	mutex_unlock(&sl->master->list_mutex);
703 
704 	return 0;
705 }
706 
707 int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
708 {
709 	struct w1_slave *sl;
710 	struct w1_family *f;
711 	int err;
712 	struct w1_netlink_msg msg;
713 
714 	sl = kzalloc(sizeof(struct w1_slave), GFP_KERNEL);
715 	if (!sl) {
716 		dev_err(&dev->dev,
717 			 "%s: failed to allocate new slave device.\n",
718 			 __func__);
719 		return -ENOMEM;
720 	}
721 
722 
723 	sl->owner = THIS_MODULE;
724 	sl->master = dev;
725 	set_bit(W1_SLAVE_ACTIVE, &sl->flags);
726 
727 	memset(&msg, 0, sizeof(msg));
728 	memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
729 	atomic_set(&sl->refcnt, 1);
730 	atomic_inc(&sl->master->refcnt);
731 
732 	/* slave modules need to be loaded in a context with unlocked mutex */
733 	mutex_unlock(&dev->mutex);
734 	request_module("w1-family-0x%02x", rn->family);
735 	mutex_lock(&dev->mutex);
736 
737 	spin_lock(&w1_flock);
738 	f = w1_family_registered(rn->family);
739 	if (!f) {
740 		f= &w1_default_family;
741 		dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
742 			  rn->family, rn->family,
743 			  (unsigned long long)rn->id, rn->crc);
744 	}
745 	__w1_family_get(f);
746 	spin_unlock(&w1_flock);
747 
748 	sl->family = f;
749 
750 
751 	err = __w1_attach_slave_device(sl);
752 	if (err < 0) {
753 		dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
754 			 sl->name);
755 		w1_family_put(sl->family);
756 		atomic_dec(&sl->master->refcnt);
757 		kfree(sl);
758 		return err;
759 	}
760 
761 	sl->ttl = dev->slave_ttl;
762 	dev->slave_count++;
763 
764 	memcpy(msg.id.id, rn, sizeof(msg.id));
765 	msg.type = W1_SLAVE_ADD;
766 	w1_netlink_send(dev, &msg);
767 
768 	return 0;
769 }
770 
771 int w1_unref_slave(struct w1_slave *sl)
772 {
773 	struct w1_master *dev = sl->master;
774 	int refcnt;
775 	mutex_lock(&dev->list_mutex);
776 	refcnt = atomic_sub_return(1, &sl->refcnt);
777 	if (refcnt == 0) {
778 		struct w1_netlink_msg msg;
779 
780 		dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__,
781 			sl->name, sl);
782 
783 		list_del(&sl->w1_slave_entry);
784 
785 		memset(&msg, 0, sizeof(msg));
786 		memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
787 		msg.type = W1_SLAVE_REMOVE;
788 		w1_netlink_send(sl->master, &msg);
789 
790 		w1_family_notify(BUS_NOTIFY_DEL_DEVICE, sl);
791 		device_unregister(&sl->dev);
792 		#ifdef DEBUG
793 		memset(sl, 0, sizeof(*sl));
794 		#endif
795 		kfree(sl);
796 	}
797 	atomic_dec(&dev->refcnt);
798 	mutex_unlock(&dev->list_mutex);
799 	return refcnt;
800 }
801 
802 int w1_slave_detach(struct w1_slave *sl)
803 {
804 	/* Only detach a slave once as it decreases the refcnt each time. */
805 	int destroy_now;
806 	mutex_lock(&sl->master->list_mutex);
807 	destroy_now = !test_bit(W1_SLAVE_DETACH, &sl->flags);
808 	set_bit(W1_SLAVE_DETACH, &sl->flags);
809 	mutex_unlock(&sl->master->list_mutex);
810 
811 	if (destroy_now)
812 		destroy_now = !w1_unref_slave(sl);
813 	return destroy_now ? 0 : -EBUSY;
814 }
815 
816 struct w1_master *w1_search_master_id(u32 id)
817 {
818 	struct w1_master *dev;
819 	int found = 0;
820 
821 	mutex_lock(&w1_mlock);
822 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
823 		if (dev->id == id) {
824 			found = 1;
825 			atomic_inc(&dev->refcnt);
826 			break;
827 		}
828 	}
829 	mutex_unlock(&w1_mlock);
830 
831 	return (found)?dev:NULL;
832 }
833 
834 struct w1_slave *w1_search_slave(struct w1_reg_num *id)
835 {
836 	struct w1_master *dev;
837 	struct w1_slave *sl = NULL;
838 	int found = 0;
839 
840 	mutex_lock(&w1_mlock);
841 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
842 		mutex_lock(&dev->list_mutex);
843 		list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
844 			if (sl->reg_num.family == id->family &&
845 					sl->reg_num.id == id->id &&
846 					sl->reg_num.crc == id->crc) {
847 				found = 1;
848 				atomic_inc(&dev->refcnt);
849 				atomic_inc(&sl->refcnt);
850 				break;
851 			}
852 		}
853 		mutex_unlock(&dev->list_mutex);
854 
855 		if (found)
856 			break;
857 	}
858 	mutex_unlock(&w1_mlock);
859 
860 	return (found)?sl:NULL;
861 }
862 
863 void w1_reconnect_slaves(struct w1_family *f, int attach)
864 {
865 	struct w1_slave *sl, *sln;
866 	struct w1_master *dev;
867 
868 	mutex_lock(&w1_mlock);
869 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
870 		dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
871 			"for family %02x.\n", dev->name, f->fid);
872 		mutex_lock(&dev->mutex);
873 		mutex_lock(&dev->list_mutex);
874 		list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
875 			/* If it is a new family, slaves with the default
876 			 * family driver and are that family will be
877 			 * connected.  If the family is going away, devices
878 			 * matching that family are reconneced.
879 			 */
880 			if ((attach && sl->family->fid == W1_FAMILY_DEFAULT
881 				&& sl->reg_num.family == f->fid) ||
882 				(!attach && sl->family->fid == f->fid)) {
883 				struct w1_reg_num rn;
884 
885 				mutex_unlock(&dev->list_mutex);
886 				memcpy(&rn, &sl->reg_num, sizeof(rn));
887 				/* If it was already in use let the automatic
888 				 * scan pick it up again later.
889 				 */
890 				if (!w1_slave_detach(sl))
891 					w1_attach_slave_device(dev, &rn);
892 				mutex_lock(&dev->list_mutex);
893 			}
894 		}
895 		dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
896 			"has been finished.\n", dev->name);
897 		mutex_unlock(&dev->list_mutex);
898 		mutex_unlock(&dev->mutex);
899 	}
900 	mutex_unlock(&w1_mlock);
901 }
902 
903 void w1_slave_found(struct w1_master *dev, u64 rn)
904 {
905 	struct w1_slave *sl;
906 	struct w1_reg_num *tmp;
907 	u64 rn_le = cpu_to_le64(rn);
908 
909 	atomic_inc(&dev->refcnt);
910 
911 	tmp = (struct w1_reg_num *) &rn;
912 
913 	sl = w1_slave_search_device(dev, tmp);
914 	if (sl) {
915 		set_bit(W1_SLAVE_ACTIVE, &sl->flags);
916 	} else {
917 		if (rn && tmp->crc == w1_calc_crc8((u8 *)&rn_le, 7))
918 			w1_attach_slave_device(dev, tmp);
919 	}
920 
921 	atomic_dec(&dev->refcnt);
922 }
923 
924 /**
925  * w1_search() - Performs a ROM Search & registers any devices found.
926  * @dev: The master device to search
927  * @search_type: W1_SEARCH to search all devices, or W1_ALARM_SEARCH
928  * to return only devices in the alarmed state
929  * @cb: Function to call when a device is found
930  *
931  * The 1-wire search is a simple binary tree search.
932  * For each bit of the address, we read two bits and write one bit.
933  * The bit written will put to sleep all devies that don't match that bit.
934  * When the two reads differ, the direction choice is obvious.
935  * When both bits are 0, we must choose a path to take.
936  * When we can scan all 64 bits without having to choose a path, we are done.
937  *
938  * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
939  *
940  */
941 void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
942 {
943 	u64 last_rn, rn, tmp64;
944 	int i, slave_count = 0;
945 	int last_zero, last_device;
946 	int search_bit, desc_bit;
947 	u8  triplet_ret = 0;
948 
949 	search_bit = 0;
950 	rn = dev->search_id;
951 	last_rn = 0;
952 	last_device = 0;
953 	last_zero = -1;
954 
955 	desc_bit = 64;
956 
957 	while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
958 		last_rn = rn;
959 		rn = 0;
960 
961 		/*
962 		 * Reset bus and all 1-wire device state machines
963 		 * so they can respond to our requests.
964 		 *
965 		 * Return 0 - device(s) present, 1 - no devices present.
966 		 */
967 		mutex_lock(&dev->bus_mutex);
968 		if (w1_reset_bus(dev)) {
969 			mutex_unlock(&dev->bus_mutex);
970 			dev_dbg(&dev->dev, "No devices present on the wire.\n");
971 			break;
972 		}
973 
974 		/* Do fast search on single slave bus */
975 		if (dev->max_slave_count == 1) {
976 			int rv;
977 			w1_write_8(dev, W1_READ_ROM);
978 			rv = w1_read_block(dev, (u8 *)&rn, 8);
979 			mutex_unlock(&dev->bus_mutex);
980 
981 			if (rv == 8 && rn)
982 				cb(dev, rn);
983 
984 			break;
985 		}
986 
987 		/* Start the search */
988 		w1_write_8(dev, search_type);
989 		for (i = 0; i < 64; ++i) {
990 			/* Determine the direction/search bit */
991 			if (i == desc_bit)
992 				search_bit = 1;	  /* took the 0 path last time, so take the 1 path */
993 			else if (i > desc_bit)
994 				search_bit = 0;	  /* take the 0 path on the next branch */
995 			else
996 				search_bit = ((last_rn >> i) & 0x1);
997 
998 			/* Read two bits and write one bit */
999 			triplet_ret = w1_triplet(dev, search_bit);
1000 
1001 			/* quit if no device responded */
1002 			if ( (triplet_ret & 0x03) == 0x03 )
1003 				break;
1004 
1005 			/* If both directions were valid, and we took the 0 path... */
1006 			if (triplet_ret == 0)
1007 				last_zero = i;
1008 
1009 			/* extract the direction taken & update the device number */
1010 			tmp64 = (triplet_ret >> 2);
1011 			rn |= (tmp64 << i);
1012 
1013 			if (test_bit(W1_ABORT_SEARCH, &dev->flags)) {
1014 				mutex_unlock(&dev->bus_mutex);
1015 				dev_dbg(&dev->dev, "Abort w1_search\n");
1016 				return;
1017 			}
1018 		}
1019 		mutex_unlock(&dev->bus_mutex);
1020 
1021 		if ( (triplet_ret & 0x03) != 0x03 ) {
1022 			if ((desc_bit == last_zero) || (last_zero < 0)) {
1023 				last_device = 1;
1024 				dev->search_id = 0;
1025 			} else {
1026 				dev->search_id = rn;
1027 			}
1028 			desc_bit = last_zero;
1029 			cb(dev, rn);
1030 		}
1031 
1032 		if (!last_device && slave_count == dev->max_slave_count &&
1033 			!test_bit(W1_WARN_MAX_COUNT, &dev->flags)) {
1034 			/* Only max_slave_count will be scanned in a search,
1035 			 * but it will start where it left off next search
1036 			 * until all ids are identified and then it will start
1037 			 * over.  A continued search will report the previous
1038 			 * last id as the first id (provided it is still on the
1039 			 * bus).
1040 			 */
1041 			dev_info(&dev->dev, "%s: max_slave_count %d reached, "
1042 				"will continue next search.\n", __func__,
1043 				dev->max_slave_count);
1044 			set_bit(W1_WARN_MAX_COUNT, &dev->flags);
1045 		}
1046 	}
1047 }
1048 
1049 void w1_search_process_cb(struct w1_master *dev, u8 search_type,
1050 	w1_slave_found_callback cb)
1051 {
1052 	struct w1_slave *sl, *sln;
1053 
1054 	mutex_lock(&dev->list_mutex);
1055 	list_for_each_entry(sl, &dev->slist, w1_slave_entry)
1056 		clear_bit(W1_SLAVE_ACTIVE, &sl->flags);
1057 	mutex_unlock(&dev->list_mutex);
1058 
1059 	w1_search_devices(dev, search_type, cb);
1060 
1061 	mutex_lock(&dev->list_mutex);
1062 	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
1063 		if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) {
1064 			mutex_unlock(&dev->list_mutex);
1065 			w1_slave_detach(sl);
1066 			mutex_lock(&dev->list_mutex);
1067 		}
1068 		else if (test_bit(W1_SLAVE_ACTIVE, &sl->flags))
1069 			sl->ttl = dev->slave_ttl;
1070 	}
1071 	mutex_unlock(&dev->list_mutex);
1072 
1073 	if (dev->search_count > 0)
1074 		dev->search_count--;
1075 }
1076 
1077 static void w1_search_process(struct w1_master *dev, u8 search_type)
1078 {
1079 	w1_search_process_cb(dev, search_type, w1_slave_found);
1080 }
1081 
1082 /**
1083  * w1_process_callbacks() - execute each dev->async_list callback entry
1084  * @dev: w1_master device
1085  *
1086  * The w1 master list_mutex must be held.
1087  *
1088  * Return: 1 if there were commands to executed 0 otherwise
1089  */
1090 int w1_process_callbacks(struct w1_master *dev)
1091 {
1092 	int ret = 0;
1093 	struct w1_async_cmd *async_cmd, *async_n;
1094 
1095 	/* The list can be added to in another thread, loop until it is empty */
1096 	while (!list_empty(&dev->async_list)) {
1097 		list_for_each_entry_safe(async_cmd, async_n, &dev->async_list,
1098 			async_entry) {
1099 			/* drop the lock, if it is a search it can take a long
1100 			 * time */
1101 			mutex_unlock(&dev->list_mutex);
1102 			async_cmd->cb(dev, async_cmd);
1103 			ret = 1;
1104 			mutex_lock(&dev->list_mutex);
1105 		}
1106 	}
1107 	return ret;
1108 }
1109 
1110 int w1_process(void *data)
1111 {
1112 	struct w1_master *dev = (struct w1_master *) data;
1113 	/* As long as w1_timeout is only set by a module parameter the sleep
1114 	 * time can be calculated in jiffies once.
1115 	 */
1116 	const unsigned long jtime =
1117 	  usecs_to_jiffies(w1_timeout * 1000000 + w1_timeout_us);
1118 	/* remainder if it woke up early */
1119 	unsigned long jremain = 0;
1120 
1121 	for (;;) {
1122 
1123 		if (!jremain && dev->search_count) {
1124 			mutex_lock(&dev->mutex);
1125 			w1_search_process(dev, W1_SEARCH);
1126 			mutex_unlock(&dev->mutex);
1127 		}
1128 
1129 		mutex_lock(&dev->list_mutex);
1130 		/* Note, w1_process_callback drops the lock while processing,
1131 		 * but locks it again before returning.
1132 		 */
1133 		if (!w1_process_callbacks(dev) && jremain) {
1134 			/* a wake up is either to stop the thread, process
1135 			 * callbacks, or search, it isn't process callbacks, so
1136 			 * schedule a search.
1137 			 */
1138 			jremain = 1;
1139 		}
1140 
1141 		__set_current_state(TASK_INTERRUPTIBLE);
1142 
1143 		/* hold list_mutex until after interruptible to prevent loosing
1144 		 * the wakeup signal when async_cmd is added.
1145 		 */
1146 		mutex_unlock(&dev->list_mutex);
1147 
1148 		if (kthread_should_stop())
1149 			break;
1150 
1151 		/* Only sleep when the search is active. */
1152 		if (dev->search_count) {
1153 			if (!jremain)
1154 				jremain = jtime;
1155 			jremain = schedule_timeout(jremain);
1156 		}
1157 		else
1158 			schedule();
1159 	}
1160 
1161 	atomic_dec(&dev->refcnt);
1162 
1163 	return 0;
1164 }
1165 
1166 static int __init w1_init(void)
1167 {
1168 	int retval;
1169 
1170 	pr_info("Driver for 1-wire Dallas network protocol.\n");
1171 
1172 	w1_init_netlink();
1173 
1174 	retval = bus_register(&w1_bus_type);
1175 	if (retval) {
1176 		pr_err("Failed to register bus. err=%d.\n", retval);
1177 		goto err_out_exit_init;
1178 	}
1179 
1180 	retval = driver_register(&w1_master_driver);
1181 	if (retval) {
1182 		pr_err("Failed to register master driver. err=%d.\n",
1183 			retval);
1184 		goto err_out_bus_unregister;
1185 	}
1186 
1187 	retval = driver_register(&w1_slave_driver);
1188 	if (retval) {
1189 		pr_err("Failed to register slave driver. err=%d.\n",
1190 			retval);
1191 		goto err_out_master_unregister;
1192 	}
1193 
1194 	return 0;
1195 
1196 #if 0
1197 /* For undoing the slave register if there was a step after it. */
1198 err_out_slave_unregister:
1199 	driver_unregister(&w1_slave_driver);
1200 #endif
1201 
1202 err_out_master_unregister:
1203 	driver_unregister(&w1_master_driver);
1204 
1205 err_out_bus_unregister:
1206 	bus_unregister(&w1_bus_type);
1207 
1208 err_out_exit_init:
1209 	return retval;
1210 }
1211 
1212 static void __exit w1_fini(void)
1213 {
1214 	struct w1_master *dev;
1215 
1216 	/* Set netlink removal messages and some cleanup */
1217 	list_for_each_entry(dev, &w1_masters, w1_master_entry)
1218 		__w1_remove_master_device(dev);
1219 
1220 	w1_fini_netlink();
1221 
1222 	driver_unregister(&w1_slave_driver);
1223 	driver_unregister(&w1_master_driver);
1224 	bus_unregister(&w1_bus_type);
1225 }
1226 
1227 module_init(w1_init);
1228 module_exit(w1_fini);
1229 
1230 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
1231 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
1232 MODULE_LICENSE("GPL");
1233