xref: /openbmc/linux/drivers/base/core.c (revision 4f205687)
1 /*
2  * drivers/base/core.c - core driver model code (device registration, etc)
3  *
4  * Copyright (c) 2002-3 Patrick Mochel
5  * Copyright (c) 2002-3 Open Source Development Labs
6  * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
7  * Copyright (c) 2006 Novell, Inc.
8  *
9  * This file is released under the GPLv2
10  *
11  */
12 
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/fwnode.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/string.h>
20 #include <linux/kdev_t.h>
21 #include <linux/notifier.h>
22 #include <linux/of.h>
23 #include <linux/of_device.h>
24 #include <linux/genhd.h>
25 #include <linux/kallsyms.h>
26 #include <linux/mutex.h>
27 #include <linux/pm_runtime.h>
28 #include <linux/netdevice.h>
29 #include <linux/sysfs.h>
30 
31 #include "base.h"
32 #include "power/power.h"
33 
34 #ifdef CONFIG_SYSFS_DEPRECATED
35 #ifdef CONFIG_SYSFS_DEPRECATED_V2
36 long sysfs_deprecated = 1;
37 #else
38 long sysfs_deprecated = 0;
39 #endif
40 static int __init sysfs_deprecated_setup(char *arg)
41 {
42 	return kstrtol(arg, 10, &sysfs_deprecated);
43 }
44 early_param("sysfs.deprecated", sysfs_deprecated_setup);
45 #endif
46 
47 int (*platform_notify)(struct device *dev) = NULL;
48 int (*platform_notify_remove)(struct device *dev) = NULL;
49 static struct kobject *dev_kobj;
50 struct kobject *sysfs_dev_char_kobj;
51 struct kobject *sysfs_dev_block_kobj;
52 
53 static DEFINE_MUTEX(device_hotplug_lock);
54 
55 void lock_device_hotplug(void)
56 {
57 	mutex_lock(&device_hotplug_lock);
58 }
59 
60 void unlock_device_hotplug(void)
61 {
62 	mutex_unlock(&device_hotplug_lock);
63 }
64 
65 int lock_device_hotplug_sysfs(void)
66 {
67 	if (mutex_trylock(&device_hotplug_lock))
68 		return 0;
69 
70 	/* Avoid busy looping (5 ms of sleep should do). */
71 	msleep(5);
72 	return restart_syscall();
73 }
74 
75 #ifdef CONFIG_BLOCK
76 static inline int device_is_not_partition(struct device *dev)
77 {
78 	return !(dev->type == &part_type);
79 }
80 #else
81 static inline int device_is_not_partition(struct device *dev)
82 {
83 	return 1;
84 }
85 #endif
86 
87 /**
88  * dev_driver_string - Return a device's driver name, if at all possible
89  * @dev: struct device to get the name of
90  *
91  * Will return the device's driver's name if it is bound to a device.  If
92  * the device is not bound to a driver, it will return the name of the bus
93  * it is attached to.  If it is not attached to a bus either, an empty
94  * string will be returned.
95  */
96 const char *dev_driver_string(const struct device *dev)
97 {
98 	struct device_driver *drv;
99 
100 	/* dev->driver can change to NULL underneath us because of unbinding,
101 	 * so be careful about accessing it.  dev->bus and dev->class should
102 	 * never change once they are set, so they don't need special care.
103 	 */
104 	drv = ACCESS_ONCE(dev->driver);
105 	return drv ? drv->name :
106 			(dev->bus ? dev->bus->name :
107 			(dev->class ? dev->class->name : ""));
108 }
109 EXPORT_SYMBOL(dev_driver_string);
110 
111 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
112 
113 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
114 			     char *buf)
115 {
116 	struct device_attribute *dev_attr = to_dev_attr(attr);
117 	struct device *dev = kobj_to_dev(kobj);
118 	ssize_t ret = -EIO;
119 
120 	if (dev_attr->show)
121 		ret = dev_attr->show(dev, dev_attr, buf);
122 	if (ret >= (ssize_t)PAGE_SIZE) {
123 		print_symbol("dev_attr_show: %s returned bad count\n",
124 				(unsigned long)dev_attr->show);
125 	}
126 	return ret;
127 }
128 
129 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
130 			      const char *buf, size_t count)
131 {
132 	struct device_attribute *dev_attr = to_dev_attr(attr);
133 	struct device *dev = kobj_to_dev(kobj);
134 	ssize_t ret = -EIO;
135 
136 	if (dev_attr->store)
137 		ret = dev_attr->store(dev, dev_attr, buf, count);
138 	return ret;
139 }
140 
141 static const struct sysfs_ops dev_sysfs_ops = {
142 	.show	= dev_attr_show,
143 	.store	= dev_attr_store,
144 };
145 
146 #define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
147 
148 ssize_t device_store_ulong(struct device *dev,
149 			   struct device_attribute *attr,
150 			   const char *buf, size_t size)
151 {
152 	struct dev_ext_attribute *ea = to_ext_attr(attr);
153 	char *end;
154 	unsigned long new = simple_strtoul(buf, &end, 0);
155 	if (end == buf)
156 		return -EINVAL;
157 	*(unsigned long *)(ea->var) = new;
158 	/* Always return full write size even if we didn't consume all */
159 	return size;
160 }
161 EXPORT_SYMBOL_GPL(device_store_ulong);
162 
163 ssize_t device_show_ulong(struct device *dev,
164 			  struct device_attribute *attr,
165 			  char *buf)
166 {
167 	struct dev_ext_attribute *ea = to_ext_attr(attr);
168 	return snprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var));
169 }
170 EXPORT_SYMBOL_GPL(device_show_ulong);
171 
172 ssize_t device_store_int(struct device *dev,
173 			 struct device_attribute *attr,
174 			 const char *buf, size_t size)
175 {
176 	struct dev_ext_attribute *ea = to_ext_attr(attr);
177 	char *end;
178 	long new = simple_strtol(buf, &end, 0);
179 	if (end == buf || new > INT_MAX || new < INT_MIN)
180 		return -EINVAL;
181 	*(int *)(ea->var) = new;
182 	/* Always return full write size even if we didn't consume all */
183 	return size;
184 }
185 EXPORT_SYMBOL_GPL(device_store_int);
186 
187 ssize_t device_show_int(struct device *dev,
188 			struct device_attribute *attr,
189 			char *buf)
190 {
191 	struct dev_ext_attribute *ea = to_ext_attr(attr);
192 
193 	return snprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var));
194 }
195 EXPORT_SYMBOL_GPL(device_show_int);
196 
197 ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
198 			  const char *buf, size_t size)
199 {
200 	struct dev_ext_attribute *ea = to_ext_attr(attr);
201 
202 	if (strtobool(buf, ea->var) < 0)
203 		return -EINVAL;
204 
205 	return size;
206 }
207 EXPORT_SYMBOL_GPL(device_store_bool);
208 
209 ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
210 			 char *buf)
211 {
212 	struct dev_ext_attribute *ea = to_ext_attr(attr);
213 
214 	return snprintf(buf, PAGE_SIZE, "%d\n", *(bool *)(ea->var));
215 }
216 EXPORT_SYMBOL_GPL(device_show_bool);
217 
218 /**
219  * device_release - free device structure.
220  * @kobj: device's kobject.
221  *
222  * This is called once the reference count for the object
223  * reaches 0. We forward the call to the device's release
224  * method, which should handle actually freeing the structure.
225  */
226 static void device_release(struct kobject *kobj)
227 {
228 	struct device *dev = kobj_to_dev(kobj);
229 	struct device_private *p = dev->p;
230 
231 	/*
232 	 * Some platform devices are driven without driver attached
233 	 * and managed resources may have been acquired.  Make sure
234 	 * all resources are released.
235 	 *
236 	 * Drivers still can add resources into device after device
237 	 * is deleted but alive, so release devres here to avoid
238 	 * possible memory leak.
239 	 */
240 	devres_release_all(dev);
241 
242 	if (dev->release)
243 		dev->release(dev);
244 	else if (dev->type && dev->type->release)
245 		dev->type->release(dev);
246 	else if (dev->class && dev->class->dev_release)
247 		dev->class->dev_release(dev);
248 	else
249 		WARN(1, KERN_ERR "Device '%s' does not have a release() "
250 			"function, it is broken and must be fixed.\n",
251 			dev_name(dev));
252 	kfree(p);
253 }
254 
255 static const void *device_namespace(struct kobject *kobj)
256 {
257 	struct device *dev = kobj_to_dev(kobj);
258 	const void *ns = NULL;
259 
260 	if (dev->class && dev->class->ns_type)
261 		ns = dev->class->namespace(dev);
262 
263 	return ns;
264 }
265 
266 static struct kobj_type device_ktype = {
267 	.release	= device_release,
268 	.sysfs_ops	= &dev_sysfs_ops,
269 	.namespace	= device_namespace,
270 };
271 
272 
273 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
274 {
275 	struct kobj_type *ktype = get_ktype(kobj);
276 
277 	if (ktype == &device_ktype) {
278 		struct device *dev = kobj_to_dev(kobj);
279 		if (dev->bus)
280 			return 1;
281 		if (dev->class)
282 			return 1;
283 	}
284 	return 0;
285 }
286 
287 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
288 {
289 	struct device *dev = kobj_to_dev(kobj);
290 
291 	if (dev->bus)
292 		return dev->bus->name;
293 	if (dev->class)
294 		return dev->class->name;
295 	return NULL;
296 }
297 
298 static int dev_uevent(struct kset *kset, struct kobject *kobj,
299 		      struct kobj_uevent_env *env)
300 {
301 	struct device *dev = kobj_to_dev(kobj);
302 	int retval = 0;
303 
304 	/* add device node properties if present */
305 	if (MAJOR(dev->devt)) {
306 		const char *tmp;
307 		const char *name;
308 		umode_t mode = 0;
309 		kuid_t uid = GLOBAL_ROOT_UID;
310 		kgid_t gid = GLOBAL_ROOT_GID;
311 
312 		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
313 		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
314 		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
315 		if (name) {
316 			add_uevent_var(env, "DEVNAME=%s", name);
317 			if (mode)
318 				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
319 			if (!uid_eq(uid, GLOBAL_ROOT_UID))
320 				add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
321 			if (!gid_eq(gid, GLOBAL_ROOT_GID))
322 				add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
323 			kfree(tmp);
324 		}
325 	}
326 
327 	if (dev->type && dev->type->name)
328 		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
329 
330 	if (dev->driver)
331 		add_uevent_var(env, "DRIVER=%s", dev->driver->name);
332 
333 	/* Add common DT information about the device */
334 	of_device_uevent(dev, env);
335 
336 	/* have the bus specific function add its stuff */
337 	if (dev->bus && dev->bus->uevent) {
338 		retval = dev->bus->uevent(dev, env);
339 		if (retval)
340 			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
341 				 dev_name(dev), __func__, retval);
342 	}
343 
344 	/* have the class specific function add its stuff */
345 	if (dev->class && dev->class->dev_uevent) {
346 		retval = dev->class->dev_uevent(dev, env);
347 		if (retval)
348 			pr_debug("device: '%s': %s: class uevent() "
349 				 "returned %d\n", dev_name(dev),
350 				 __func__, retval);
351 	}
352 
353 	/* have the device type specific function add its stuff */
354 	if (dev->type && dev->type->uevent) {
355 		retval = dev->type->uevent(dev, env);
356 		if (retval)
357 			pr_debug("device: '%s': %s: dev_type uevent() "
358 				 "returned %d\n", dev_name(dev),
359 				 __func__, retval);
360 	}
361 
362 	return retval;
363 }
364 
365 static const struct kset_uevent_ops device_uevent_ops = {
366 	.filter =	dev_uevent_filter,
367 	.name =		dev_uevent_name,
368 	.uevent =	dev_uevent,
369 };
370 
371 static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
372 			   char *buf)
373 {
374 	struct kobject *top_kobj;
375 	struct kset *kset;
376 	struct kobj_uevent_env *env = NULL;
377 	int i;
378 	size_t count = 0;
379 	int retval;
380 
381 	/* search the kset, the device belongs to */
382 	top_kobj = &dev->kobj;
383 	while (!top_kobj->kset && top_kobj->parent)
384 		top_kobj = top_kobj->parent;
385 	if (!top_kobj->kset)
386 		goto out;
387 
388 	kset = top_kobj->kset;
389 	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
390 		goto out;
391 
392 	/* respect filter */
393 	if (kset->uevent_ops && kset->uevent_ops->filter)
394 		if (!kset->uevent_ops->filter(kset, &dev->kobj))
395 			goto out;
396 
397 	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
398 	if (!env)
399 		return -ENOMEM;
400 
401 	/* let the kset specific function add its keys */
402 	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
403 	if (retval)
404 		goto out;
405 
406 	/* copy keys to file */
407 	for (i = 0; i < env->envp_idx; i++)
408 		count += sprintf(&buf[count], "%s\n", env->envp[i]);
409 out:
410 	kfree(env);
411 	return count;
412 }
413 
414 static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
415 			    const char *buf, size_t count)
416 {
417 	enum kobject_action action;
418 
419 	if (kobject_action_type(buf, count, &action) == 0)
420 		kobject_uevent(&dev->kobj, action);
421 	else
422 		dev_err(dev, "uevent: unknown action-string\n");
423 	return count;
424 }
425 static DEVICE_ATTR_RW(uevent);
426 
427 static ssize_t online_show(struct device *dev, struct device_attribute *attr,
428 			   char *buf)
429 {
430 	bool val;
431 
432 	device_lock(dev);
433 	val = !dev->offline;
434 	device_unlock(dev);
435 	return sprintf(buf, "%u\n", val);
436 }
437 
438 static ssize_t online_store(struct device *dev, struct device_attribute *attr,
439 			    const char *buf, size_t count)
440 {
441 	bool val;
442 	int ret;
443 
444 	ret = strtobool(buf, &val);
445 	if (ret < 0)
446 		return ret;
447 
448 	ret = lock_device_hotplug_sysfs();
449 	if (ret)
450 		return ret;
451 
452 	ret = val ? device_online(dev) : device_offline(dev);
453 	unlock_device_hotplug();
454 	return ret < 0 ? ret : count;
455 }
456 static DEVICE_ATTR_RW(online);
457 
458 int device_add_groups(struct device *dev, const struct attribute_group **groups)
459 {
460 	return sysfs_create_groups(&dev->kobj, groups);
461 }
462 
463 void device_remove_groups(struct device *dev,
464 			  const struct attribute_group **groups)
465 {
466 	sysfs_remove_groups(&dev->kobj, groups);
467 }
468 
469 static int device_add_attrs(struct device *dev)
470 {
471 	struct class *class = dev->class;
472 	const struct device_type *type = dev->type;
473 	int error;
474 
475 	if (class) {
476 		error = device_add_groups(dev, class->dev_groups);
477 		if (error)
478 			return error;
479 	}
480 
481 	if (type) {
482 		error = device_add_groups(dev, type->groups);
483 		if (error)
484 			goto err_remove_class_groups;
485 	}
486 
487 	error = device_add_groups(dev, dev->groups);
488 	if (error)
489 		goto err_remove_type_groups;
490 
491 	if (device_supports_offline(dev) && !dev->offline_disabled) {
492 		error = device_create_file(dev, &dev_attr_online);
493 		if (error)
494 			goto err_remove_dev_groups;
495 	}
496 
497 	return 0;
498 
499  err_remove_dev_groups:
500 	device_remove_groups(dev, dev->groups);
501  err_remove_type_groups:
502 	if (type)
503 		device_remove_groups(dev, type->groups);
504  err_remove_class_groups:
505 	if (class)
506 		device_remove_groups(dev, class->dev_groups);
507 
508 	return error;
509 }
510 
511 static void device_remove_attrs(struct device *dev)
512 {
513 	struct class *class = dev->class;
514 	const struct device_type *type = dev->type;
515 
516 	device_remove_file(dev, &dev_attr_online);
517 	device_remove_groups(dev, dev->groups);
518 
519 	if (type)
520 		device_remove_groups(dev, type->groups);
521 
522 	if (class)
523 		device_remove_groups(dev, class->dev_groups);
524 }
525 
526 static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
527 			char *buf)
528 {
529 	return print_dev_t(buf, dev->devt);
530 }
531 static DEVICE_ATTR_RO(dev);
532 
533 /* /sys/devices/ */
534 struct kset *devices_kset;
535 
536 /**
537  * devices_kset_move_before - Move device in the devices_kset's list.
538  * @deva: Device to move.
539  * @devb: Device @deva should come before.
540  */
541 static void devices_kset_move_before(struct device *deva, struct device *devb)
542 {
543 	if (!devices_kset)
544 		return;
545 	pr_debug("devices_kset: Moving %s before %s\n",
546 		 dev_name(deva), dev_name(devb));
547 	spin_lock(&devices_kset->list_lock);
548 	list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
549 	spin_unlock(&devices_kset->list_lock);
550 }
551 
552 /**
553  * devices_kset_move_after - Move device in the devices_kset's list.
554  * @deva: Device to move
555  * @devb: Device @deva should come after.
556  */
557 static void devices_kset_move_after(struct device *deva, struct device *devb)
558 {
559 	if (!devices_kset)
560 		return;
561 	pr_debug("devices_kset: Moving %s after %s\n",
562 		 dev_name(deva), dev_name(devb));
563 	spin_lock(&devices_kset->list_lock);
564 	list_move(&deva->kobj.entry, &devb->kobj.entry);
565 	spin_unlock(&devices_kset->list_lock);
566 }
567 
568 /**
569  * devices_kset_move_last - move the device to the end of devices_kset's list.
570  * @dev: device to move
571  */
572 void devices_kset_move_last(struct device *dev)
573 {
574 	if (!devices_kset)
575 		return;
576 	pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
577 	spin_lock(&devices_kset->list_lock);
578 	list_move_tail(&dev->kobj.entry, &devices_kset->list);
579 	spin_unlock(&devices_kset->list_lock);
580 }
581 
582 /**
583  * device_create_file - create sysfs attribute file for device.
584  * @dev: device.
585  * @attr: device attribute descriptor.
586  */
587 int device_create_file(struct device *dev,
588 		       const struct device_attribute *attr)
589 {
590 	int error = 0;
591 
592 	if (dev) {
593 		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
594 			"Attribute %s: write permission without 'store'\n",
595 			attr->attr.name);
596 		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
597 			"Attribute %s: read permission without 'show'\n",
598 			attr->attr.name);
599 		error = sysfs_create_file(&dev->kobj, &attr->attr);
600 	}
601 
602 	return error;
603 }
604 EXPORT_SYMBOL_GPL(device_create_file);
605 
606 /**
607  * device_remove_file - remove sysfs attribute file.
608  * @dev: device.
609  * @attr: device attribute descriptor.
610  */
611 void device_remove_file(struct device *dev,
612 			const struct device_attribute *attr)
613 {
614 	if (dev)
615 		sysfs_remove_file(&dev->kobj, &attr->attr);
616 }
617 EXPORT_SYMBOL_GPL(device_remove_file);
618 
619 /**
620  * device_remove_file_self - remove sysfs attribute file from its own method.
621  * @dev: device.
622  * @attr: device attribute descriptor.
623  *
624  * See kernfs_remove_self() for details.
625  */
626 bool device_remove_file_self(struct device *dev,
627 			     const struct device_attribute *attr)
628 {
629 	if (dev)
630 		return sysfs_remove_file_self(&dev->kobj, &attr->attr);
631 	else
632 		return false;
633 }
634 EXPORT_SYMBOL_GPL(device_remove_file_self);
635 
636 /**
637  * device_create_bin_file - create sysfs binary attribute file for device.
638  * @dev: device.
639  * @attr: device binary attribute descriptor.
640  */
641 int device_create_bin_file(struct device *dev,
642 			   const struct bin_attribute *attr)
643 {
644 	int error = -EINVAL;
645 	if (dev)
646 		error = sysfs_create_bin_file(&dev->kobj, attr);
647 	return error;
648 }
649 EXPORT_SYMBOL_GPL(device_create_bin_file);
650 
651 /**
652  * device_remove_bin_file - remove sysfs binary attribute file
653  * @dev: device.
654  * @attr: device binary attribute descriptor.
655  */
656 void device_remove_bin_file(struct device *dev,
657 			    const struct bin_attribute *attr)
658 {
659 	if (dev)
660 		sysfs_remove_bin_file(&dev->kobj, attr);
661 }
662 EXPORT_SYMBOL_GPL(device_remove_bin_file);
663 
664 static void klist_children_get(struct klist_node *n)
665 {
666 	struct device_private *p = to_device_private_parent(n);
667 	struct device *dev = p->device;
668 
669 	get_device(dev);
670 }
671 
672 static void klist_children_put(struct klist_node *n)
673 {
674 	struct device_private *p = to_device_private_parent(n);
675 	struct device *dev = p->device;
676 
677 	put_device(dev);
678 }
679 
680 /**
681  * device_initialize - init device structure.
682  * @dev: device.
683  *
684  * This prepares the device for use by other layers by initializing
685  * its fields.
686  * It is the first half of device_register(), if called by
687  * that function, though it can also be called separately, so one
688  * may use @dev's fields. In particular, get_device()/put_device()
689  * may be used for reference counting of @dev after calling this
690  * function.
691  *
692  * All fields in @dev must be initialized by the caller to 0, except
693  * for those explicitly set to some other value.  The simplest
694  * approach is to use kzalloc() to allocate the structure containing
695  * @dev.
696  *
697  * NOTE: Use put_device() to give up your reference instead of freeing
698  * @dev directly once you have called this function.
699  */
700 void device_initialize(struct device *dev)
701 {
702 	dev->kobj.kset = devices_kset;
703 	kobject_init(&dev->kobj, &device_ktype);
704 	INIT_LIST_HEAD(&dev->dma_pools);
705 	mutex_init(&dev->mutex);
706 	lockdep_set_novalidate_class(&dev->mutex);
707 	spin_lock_init(&dev->devres_lock);
708 	INIT_LIST_HEAD(&dev->devres_head);
709 	device_pm_init(dev);
710 	set_dev_node(dev, -1);
711 #ifdef CONFIG_GENERIC_MSI_IRQ
712 	INIT_LIST_HEAD(&dev->msi_list);
713 #endif
714 }
715 EXPORT_SYMBOL_GPL(device_initialize);
716 
717 struct kobject *virtual_device_parent(struct device *dev)
718 {
719 	static struct kobject *virtual_dir = NULL;
720 
721 	if (!virtual_dir)
722 		virtual_dir = kobject_create_and_add("virtual",
723 						     &devices_kset->kobj);
724 
725 	return virtual_dir;
726 }
727 
728 struct class_dir {
729 	struct kobject kobj;
730 	struct class *class;
731 };
732 
733 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
734 
735 static void class_dir_release(struct kobject *kobj)
736 {
737 	struct class_dir *dir = to_class_dir(kobj);
738 	kfree(dir);
739 }
740 
741 static const
742 struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
743 {
744 	struct class_dir *dir = to_class_dir(kobj);
745 	return dir->class->ns_type;
746 }
747 
748 static struct kobj_type class_dir_ktype = {
749 	.release	= class_dir_release,
750 	.sysfs_ops	= &kobj_sysfs_ops,
751 	.child_ns_type	= class_dir_child_ns_type
752 };
753 
754 static struct kobject *
755 class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
756 {
757 	struct class_dir *dir;
758 	int retval;
759 
760 	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
761 	if (!dir)
762 		return NULL;
763 
764 	dir->class = class;
765 	kobject_init(&dir->kobj, &class_dir_ktype);
766 
767 	dir->kobj.kset = &class->p->glue_dirs;
768 
769 	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
770 	if (retval < 0) {
771 		kobject_put(&dir->kobj);
772 		return NULL;
773 	}
774 	return &dir->kobj;
775 }
776 
777 static DEFINE_MUTEX(gdp_mutex);
778 
779 static struct kobject *get_device_parent(struct device *dev,
780 					 struct device *parent)
781 {
782 	if (dev->class) {
783 		struct kobject *kobj = NULL;
784 		struct kobject *parent_kobj;
785 		struct kobject *k;
786 
787 #ifdef CONFIG_BLOCK
788 		/* block disks show up in /sys/block */
789 		if (sysfs_deprecated && dev->class == &block_class) {
790 			if (parent && parent->class == &block_class)
791 				return &parent->kobj;
792 			return &block_class.p->subsys.kobj;
793 		}
794 #endif
795 
796 		/*
797 		 * If we have no parent, we live in "virtual".
798 		 * Class-devices with a non class-device as parent, live
799 		 * in a "glue" directory to prevent namespace collisions.
800 		 */
801 		if (parent == NULL)
802 			parent_kobj = virtual_device_parent(dev);
803 		else if (parent->class && !dev->class->ns_type)
804 			return &parent->kobj;
805 		else
806 			parent_kobj = &parent->kobj;
807 
808 		mutex_lock(&gdp_mutex);
809 
810 		/* find our class-directory at the parent and reference it */
811 		spin_lock(&dev->class->p->glue_dirs.list_lock);
812 		list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
813 			if (k->parent == parent_kobj) {
814 				kobj = kobject_get(k);
815 				break;
816 			}
817 		spin_unlock(&dev->class->p->glue_dirs.list_lock);
818 		if (kobj) {
819 			mutex_unlock(&gdp_mutex);
820 			return kobj;
821 		}
822 
823 		/* or create a new class-directory at the parent device */
824 		k = class_dir_create_and_add(dev->class, parent_kobj);
825 		/* do not emit an uevent for this simple "glue" directory */
826 		mutex_unlock(&gdp_mutex);
827 		return k;
828 	}
829 
830 	/* subsystems can specify a default root directory for their devices */
831 	if (!parent && dev->bus && dev->bus->dev_root)
832 		return &dev->bus->dev_root->kobj;
833 
834 	if (parent)
835 		return &parent->kobj;
836 	return NULL;
837 }
838 
839 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
840 {
841 	/* see if we live in a "glue" directory */
842 	if (!glue_dir || !dev->class ||
843 	    glue_dir->kset != &dev->class->p->glue_dirs)
844 		return;
845 
846 	mutex_lock(&gdp_mutex);
847 	kobject_put(glue_dir);
848 	mutex_unlock(&gdp_mutex);
849 }
850 
851 static void cleanup_device_parent(struct device *dev)
852 {
853 	cleanup_glue_dir(dev, dev->kobj.parent);
854 }
855 
856 static int device_add_class_symlinks(struct device *dev)
857 {
858 	struct device_node *of_node = dev_of_node(dev);
859 	int error;
860 
861 	if (of_node) {
862 		error = sysfs_create_link(&dev->kobj, &of_node->kobj,"of_node");
863 		if (error)
864 			dev_warn(dev, "Error %d creating of_node link\n",error);
865 		/* An error here doesn't warrant bringing down the device */
866 	}
867 
868 	if (!dev->class)
869 		return 0;
870 
871 	error = sysfs_create_link(&dev->kobj,
872 				  &dev->class->p->subsys.kobj,
873 				  "subsystem");
874 	if (error)
875 		goto out_devnode;
876 
877 	if (dev->parent && device_is_not_partition(dev)) {
878 		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
879 					  "device");
880 		if (error)
881 			goto out_subsys;
882 	}
883 
884 #ifdef CONFIG_BLOCK
885 	/* /sys/block has directories and does not need symlinks */
886 	if (sysfs_deprecated && dev->class == &block_class)
887 		return 0;
888 #endif
889 
890 	/* link in the class directory pointing to the device */
891 	error = sysfs_create_link(&dev->class->p->subsys.kobj,
892 				  &dev->kobj, dev_name(dev));
893 	if (error)
894 		goto out_device;
895 
896 	return 0;
897 
898 out_device:
899 	sysfs_remove_link(&dev->kobj, "device");
900 
901 out_subsys:
902 	sysfs_remove_link(&dev->kobj, "subsystem");
903 out_devnode:
904 	sysfs_remove_link(&dev->kobj, "of_node");
905 	return error;
906 }
907 
908 static void device_remove_class_symlinks(struct device *dev)
909 {
910 	if (dev_of_node(dev))
911 		sysfs_remove_link(&dev->kobj, "of_node");
912 
913 	if (!dev->class)
914 		return;
915 
916 	if (dev->parent && device_is_not_partition(dev))
917 		sysfs_remove_link(&dev->kobj, "device");
918 	sysfs_remove_link(&dev->kobj, "subsystem");
919 #ifdef CONFIG_BLOCK
920 	if (sysfs_deprecated && dev->class == &block_class)
921 		return;
922 #endif
923 	sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
924 }
925 
926 /**
927  * dev_set_name - set a device name
928  * @dev: device
929  * @fmt: format string for the device's name
930  */
931 int dev_set_name(struct device *dev, const char *fmt, ...)
932 {
933 	va_list vargs;
934 	int err;
935 
936 	va_start(vargs, fmt);
937 	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
938 	va_end(vargs);
939 	return err;
940 }
941 EXPORT_SYMBOL_GPL(dev_set_name);
942 
943 /**
944  * device_to_dev_kobj - select a /sys/dev/ directory for the device
945  * @dev: device
946  *
947  * By default we select char/ for new entries.  Setting class->dev_obj
948  * to NULL prevents an entry from being created.  class->dev_kobj must
949  * be set (or cleared) before any devices are registered to the class
950  * otherwise device_create_sys_dev_entry() and
951  * device_remove_sys_dev_entry() will disagree about the presence of
952  * the link.
953  */
954 static struct kobject *device_to_dev_kobj(struct device *dev)
955 {
956 	struct kobject *kobj;
957 
958 	if (dev->class)
959 		kobj = dev->class->dev_kobj;
960 	else
961 		kobj = sysfs_dev_char_kobj;
962 
963 	return kobj;
964 }
965 
966 static int device_create_sys_dev_entry(struct device *dev)
967 {
968 	struct kobject *kobj = device_to_dev_kobj(dev);
969 	int error = 0;
970 	char devt_str[15];
971 
972 	if (kobj) {
973 		format_dev_t(devt_str, dev->devt);
974 		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
975 	}
976 
977 	return error;
978 }
979 
980 static void device_remove_sys_dev_entry(struct device *dev)
981 {
982 	struct kobject *kobj = device_to_dev_kobj(dev);
983 	char devt_str[15];
984 
985 	if (kobj) {
986 		format_dev_t(devt_str, dev->devt);
987 		sysfs_remove_link(kobj, devt_str);
988 	}
989 }
990 
991 int device_private_init(struct device *dev)
992 {
993 	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
994 	if (!dev->p)
995 		return -ENOMEM;
996 	dev->p->device = dev;
997 	klist_init(&dev->p->klist_children, klist_children_get,
998 		   klist_children_put);
999 	INIT_LIST_HEAD(&dev->p->deferred_probe);
1000 	return 0;
1001 }
1002 
1003 /**
1004  * device_add - add device to device hierarchy.
1005  * @dev: device.
1006  *
1007  * This is part 2 of device_register(), though may be called
1008  * separately _iff_ device_initialize() has been called separately.
1009  *
1010  * This adds @dev to the kobject hierarchy via kobject_add(), adds it
1011  * to the global and sibling lists for the device, then
1012  * adds it to the other relevant subsystems of the driver model.
1013  *
1014  * Do not call this routine or device_register() more than once for
1015  * any device structure.  The driver model core is not designed to work
1016  * with devices that get unregistered and then spring back to life.
1017  * (Among other things, it's very hard to guarantee that all references
1018  * to the previous incarnation of @dev have been dropped.)  Allocate
1019  * and register a fresh new struct device instead.
1020  *
1021  * NOTE: _Never_ directly free @dev after calling this function, even
1022  * if it returned an error! Always use put_device() to give up your
1023  * reference instead.
1024  */
1025 int device_add(struct device *dev)
1026 {
1027 	struct device *parent = NULL;
1028 	struct kobject *kobj;
1029 	struct class_interface *class_intf;
1030 	int error = -EINVAL;
1031 
1032 	dev = get_device(dev);
1033 	if (!dev)
1034 		goto done;
1035 
1036 	if (!dev->p) {
1037 		error = device_private_init(dev);
1038 		if (error)
1039 			goto done;
1040 	}
1041 
1042 	/*
1043 	 * for statically allocated devices, which should all be converted
1044 	 * some day, we need to initialize the name. We prevent reading back
1045 	 * the name, and force the use of dev_name()
1046 	 */
1047 	if (dev->init_name) {
1048 		dev_set_name(dev, "%s", dev->init_name);
1049 		dev->init_name = NULL;
1050 	}
1051 
1052 	/* subsystems can specify simple device enumeration */
1053 	if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
1054 		dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
1055 
1056 	if (!dev_name(dev)) {
1057 		error = -EINVAL;
1058 		goto name_error;
1059 	}
1060 
1061 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1062 
1063 	parent = get_device(dev->parent);
1064 	kobj = get_device_parent(dev, parent);
1065 	if (kobj)
1066 		dev->kobj.parent = kobj;
1067 
1068 	/* use parent numa_node */
1069 	if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
1070 		set_dev_node(dev, dev_to_node(parent));
1071 
1072 	/* first, register with generic layer. */
1073 	/* we require the name to be set before, and pass NULL */
1074 	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
1075 	if (error)
1076 		goto Error;
1077 
1078 	/* notify platform of device entry */
1079 	if (platform_notify)
1080 		platform_notify(dev);
1081 
1082 	error = device_create_file(dev, &dev_attr_uevent);
1083 	if (error)
1084 		goto attrError;
1085 
1086 	error = device_add_class_symlinks(dev);
1087 	if (error)
1088 		goto SymlinkError;
1089 	error = device_add_attrs(dev);
1090 	if (error)
1091 		goto AttrsError;
1092 	error = bus_add_device(dev);
1093 	if (error)
1094 		goto BusError;
1095 	error = dpm_sysfs_add(dev);
1096 	if (error)
1097 		goto DPMError;
1098 	device_pm_add(dev);
1099 
1100 	if (MAJOR(dev->devt)) {
1101 		error = device_create_file(dev, &dev_attr_dev);
1102 		if (error)
1103 			goto DevAttrError;
1104 
1105 		error = device_create_sys_dev_entry(dev);
1106 		if (error)
1107 			goto SysEntryError;
1108 
1109 		devtmpfs_create_node(dev);
1110 	}
1111 
1112 	/* Notify clients of device addition.  This call must come
1113 	 * after dpm_sysfs_add() and before kobject_uevent().
1114 	 */
1115 	if (dev->bus)
1116 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1117 					     BUS_NOTIFY_ADD_DEVICE, dev);
1118 
1119 	kobject_uevent(&dev->kobj, KOBJ_ADD);
1120 	bus_probe_device(dev);
1121 	if (parent)
1122 		klist_add_tail(&dev->p->knode_parent,
1123 			       &parent->p->klist_children);
1124 
1125 	if (dev->class) {
1126 		mutex_lock(&dev->class->p->mutex);
1127 		/* tie the class to the device */
1128 		klist_add_tail(&dev->knode_class,
1129 			       &dev->class->p->klist_devices);
1130 
1131 		/* notify any interfaces that the device is here */
1132 		list_for_each_entry(class_intf,
1133 				    &dev->class->p->interfaces, node)
1134 			if (class_intf->add_dev)
1135 				class_intf->add_dev(dev, class_intf);
1136 		mutex_unlock(&dev->class->p->mutex);
1137 	}
1138 done:
1139 	put_device(dev);
1140 	return error;
1141  SysEntryError:
1142 	if (MAJOR(dev->devt))
1143 		device_remove_file(dev, &dev_attr_dev);
1144  DevAttrError:
1145 	device_pm_remove(dev);
1146 	dpm_sysfs_remove(dev);
1147  DPMError:
1148 	bus_remove_device(dev);
1149  BusError:
1150 	device_remove_attrs(dev);
1151  AttrsError:
1152 	device_remove_class_symlinks(dev);
1153  SymlinkError:
1154 	device_remove_file(dev, &dev_attr_uevent);
1155  attrError:
1156 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1157 	kobject_del(&dev->kobj);
1158  Error:
1159 	cleanup_device_parent(dev);
1160 	put_device(parent);
1161 name_error:
1162 	kfree(dev->p);
1163 	dev->p = NULL;
1164 	goto done;
1165 }
1166 EXPORT_SYMBOL_GPL(device_add);
1167 
1168 /**
1169  * device_register - register a device with the system.
1170  * @dev: pointer to the device structure
1171  *
1172  * This happens in two clean steps - initialize the device
1173  * and add it to the system. The two steps can be called
1174  * separately, but this is the easiest and most common.
1175  * I.e. you should only call the two helpers separately if
1176  * have a clearly defined need to use and refcount the device
1177  * before it is added to the hierarchy.
1178  *
1179  * For more information, see the kerneldoc for device_initialize()
1180  * and device_add().
1181  *
1182  * NOTE: _Never_ directly free @dev after calling this function, even
1183  * if it returned an error! Always use put_device() to give up the
1184  * reference initialized in this function instead.
1185  */
1186 int device_register(struct device *dev)
1187 {
1188 	device_initialize(dev);
1189 	return device_add(dev);
1190 }
1191 EXPORT_SYMBOL_GPL(device_register);
1192 
1193 /**
1194  * get_device - increment reference count for device.
1195  * @dev: device.
1196  *
1197  * This simply forwards the call to kobject_get(), though
1198  * we do take care to provide for the case that we get a NULL
1199  * pointer passed in.
1200  */
1201 struct device *get_device(struct device *dev)
1202 {
1203 	return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
1204 }
1205 EXPORT_SYMBOL_GPL(get_device);
1206 
1207 /**
1208  * put_device - decrement reference count.
1209  * @dev: device in question.
1210  */
1211 void put_device(struct device *dev)
1212 {
1213 	/* might_sleep(); */
1214 	if (dev)
1215 		kobject_put(&dev->kobj);
1216 }
1217 EXPORT_SYMBOL_GPL(put_device);
1218 
1219 /**
1220  * device_del - delete device from system.
1221  * @dev: device.
1222  *
1223  * This is the first part of the device unregistration
1224  * sequence. This removes the device from the lists we control
1225  * from here, has it removed from the other driver model
1226  * subsystems it was added to in device_add(), and removes it
1227  * from the kobject hierarchy.
1228  *
1229  * NOTE: this should be called manually _iff_ device_add() was
1230  * also called manually.
1231  */
1232 void device_del(struct device *dev)
1233 {
1234 	struct device *parent = dev->parent;
1235 	struct class_interface *class_intf;
1236 
1237 	/* Notify clients of device removal.  This call must come
1238 	 * before dpm_sysfs_remove().
1239 	 */
1240 	if (dev->bus)
1241 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1242 					     BUS_NOTIFY_DEL_DEVICE, dev);
1243 	dpm_sysfs_remove(dev);
1244 	if (parent)
1245 		klist_del(&dev->p->knode_parent);
1246 	if (MAJOR(dev->devt)) {
1247 		devtmpfs_delete_node(dev);
1248 		device_remove_sys_dev_entry(dev);
1249 		device_remove_file(dev, &dev_attr_dev);
1250 	}
1251 	if (dev->class) {
1252 		device_remove_class_symlinks(dev);
1253 
1254 		mutex_lock(&dev->class->p->mutex);
1255 		/* notify any interfaces that the device is now gone */
1256 		list_for_each_entry(class_intf,
1257 				    &dev->class->p->interfaces, node)
1258 			if (class_intf->remove_dev)
1259 				class_intf->remove_dev(dev, class_intf);
1260 		/* remove the device from the class list */
1261 		klist_del(&dev->knode_class);
1262 		mutex_unlock(&dev->class->p->mutex);
1263 	}
1264 	device_remove_file(dev, &dev_attr_uevent);
1265 	device_remove_attrs(dev);
1266 	bus_remove_device(dev);
1267 	device_pm_remove(dev);
1268 	driver_deferred_probe_del(dev);
1269 
1270 	/* Notify the platform of the removal, in case they
1271 	 * need to do anything...
1272 	 */
1273 	if (platform_notify_remove)
1274 		platform_notify_remove(dev);
1275 	if (dev->bus)
1276 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1277 					     BUS_NOTIFY_REMOVED_DEVICE, dev);
1278 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
1279 	cleanup_device_parent(dev);
1280 	kobject_del(&dev->kobj);
1281 	put_device(parent);
1282 }
1283 EXPORT_SYMBOL_GPL(device_del);
1284 
1285 /**
1286  * device_unregister - unregister device from system.
1287  * @dev: device going away.
1288  *
1289  * We do this in two parts, like we do device_register(). First,
1290  * we remove it from all the subsystems with device_del(), then
1291  * we decrement the reference count via put_device(). If that
1292  * is the final reference count, the device will be cleaned up
1293  * via device_release() above. Otherwise, the structure will
1294  * stick around until the final reference to the device is dropped.
1295  */
1296 void device_unregister(struct device *dev)
1297 {
1298 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1299 	device_del(dev);
1300 	put_device(dev);
1301 }
1302 EXPORT_SYMBOL_GPL(device_unregister);
1303 
1304 static struct device *prev_device(struct klist_iter *i)
1305 {
1306 	struct klist_node *n = klist_prev(i);
1307 	struct device *dev = NULL;
1308 	struct device_private *p;
1309 
1310 	if (n) {
1311 		p = to_device_private_parent(n);
1312 		dev = p->device;
1313 	}
1314 	return dev;
1315 }
1316 
1317 static struct device *next_device(struct klist_iter *i)
1318 {
1319 	struct klist_node *n = klist_next(i);
1320 	struct device *dev = NULL;
1321 	struct device_private *p;
1322 
1323 	if (n) {
1324 		p = to_device_private_parent(n);
1325 		dev = p->device;
1326 	}
1327 	return dev;
1328 }
1329 
1330 /**
1331  * device_get_devnode - path of device node file
1332  * @dev: device
1333  * @mode: returned file access mode
1334  * @uid: returned file owner
1335  * @gid: returned file group
1336  * @tmp: possibly allocated string
1337  *
1338  * Return the relative path of a possible device node.
1339  * Non-default names may need to allocate a memory to compose
1340  * a name. This memory is returned in tmp and needs to be
1341  * freed by the caller.
1342  */
1343 const char *device_get_devnode(struct device *dev,
1344 			       umode_t *mode, kuid_t *uid, kgid_t *gid,
1345 			       const char **tmp)
1346 {
1347 	char *s;
1348 
1349 	*tmp = NULL;
1350 
1351 	/* the device type may provide a specific name */
1352 	if (dev->type && dev->type->devnode)
1353 		*tmp = dev->type->devnode(dev, mode, uid, gid);
1354 	if (*tmp)
1355 		return *tmp;
1356 
1357 	/* the class may provide a specific name */
1358 	if (dev->class && dev->class->devnode)
1359 		*tmp = dev->class->devnode(dev, mode);
1360 	if (*tmp)
1361 		return *tmp;
1362 
1363 	/* return name without allocation, tmp == NULL */
1364 	if (strchr(dev_name(dev), '!') == NULL)
1365 		return dev_name(dev);
1366 
1367 	/* replace '!' in the name with '/' */
1368 	s = kstrdup(dev_name(dev), GFP_KERNEL);
1369 	if (!s)
1370 		return NULL;
1371 	strreplace(s, '!', '/');
1372 	return *tmp = s;
1373 }
1374 
1375 /**
1376  * device_for_each_child - device child iterator.
1377  * @parent: parent struct device.
1378  * @fn: function to be called for each device.
1379  * @data: data for the callback.
1380  *
1381  * Iterate over @parent's child devices, and call @fn for each,
1382  * passing it @data.
1383  *
1384  * We check the return of @fn each time. If it returns anything
1385  * other than 0, we break out and return that value.
1386  */
1387 int device_for_each_child(struct device *parent, void *data,
1388 			  int (*fn)(struct device *dev, void *data))
1389 {
1390 	struct klist_iter i;
1391 	struct device *child;
1392 	int error = 0;
1393 
1394 	if (!parent->p)
1395 		return 0;
1396 
1397 	klist_iter_init(&parent->p->klist_children, &i);
1398 	while ((child = next_device(&i)) && !error)
1399 		error = fn(child, data);
1400 	klist_iter_exit(&i);
1401 	return error;
1402 }
1403 EXPORT_SYMBOL_GPL(device_for_each_child);
1404 
1405 /**
1406  * device_for_each_child_reverse - device child iterator in reversed order.
1407  * @parent: parent struct device.
1408  * @fn: function to be called for each device.
1409  * @data: data for the callback.
1410  *
1411  * Iterate over @parent's child devices, and call @fn for each,
1412  * passing it @data.
1413  *
1414  * We check the return of @fn each time. If it returns anything
1415  * other than 0, we break out and return that value.
1416  */
1417 int device_for_each_child_reverse(struct device *parent, void *data,
1418 				  int (*fn)(struct device *dev, void *data))
1419 {
1420 	struct klist_iter i;
1421 	struct device *child;
1422 	int error = 0;
1423 
1424 	if (!parent->p)
1425 		return 0;
1426 
1427 	klist_iter_init(&parent->p->klist_children, &i);
1428 	while ((child = prev_device(&i)) && !error)
1429 		error = fn(child, data);
1430 	klist_iter_exit(&i);
1431 	return error;
1432 }
1433 EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
1434 
1435 /**
1436  * device_find_child - device iterator for locating a particular device.
1437  * @parent: parent struct device
1438  * @match: Callback function to check device
1439  * @data: Data to pass to match function
1440  *
1441  * This is similar to the device_for_each_child() function above, but it
1442  * returns a reference to a device that is 'found' for later use, as
1443  * determined by the @match callback.
1444  *
1445  * The callback should return 0 if the device doesn't match and non-zero
1446  * if it does.  If the callback returns non-zero and a reference to the
1447  * current device can be obtained, this function will return to the caller
1448  * and not iterate over any more devices.
1449  *
1450  * NOTE: you will need to drop the reference with put_device() after use.
1451  */
1452 struct device *device_find_child(struct device *parent, void *data,
1453 				 int (*match)(struct device *dev, void *data))
1454 {
1455 	struct klist_iter i;
1456 	struct device *child;
1457 
1458 	if (!parent)
1459 		return NULL;
1460 
1461 	klist_iter_init(&parent->p->klist_children, &i);
1462 	while ((child = next_device(&i)))
1463 		if (match(child, data) && get_device(child))
1464 			break;
1465 	klist_iter_exit(&i);
1466 	return child;
1467 }
1468 EXPORT_SYMBOL_GPL(device_find_child);
1469 
1470 int __init devices_init(void)
1471 {
1472 	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
1473 	if (!devices_kset)
1474 		return -ENOMEM;
1475 	dev_kobj = kobject_create_and_add("dev", NULL);
1476 	if (!dev_kobj)
1477 		goto dev_kobj_err;
1478 	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
1479 	if (!sysfs_dev_block_kobj)
1480 		goto block_kobj_err;
1481 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
1482 	if (!sysfs_dev_char_kobj)
1483 		goto char_kobj_err;
1484 
1485 	return 0;
1486 
1487  char_kobj_err:
1488 	kobject_put(sysfs_dev_block_kobj);
1489  block_kobj_err:
1490 	kobject_put(dev_kobj);
1491  dev_kobj_err:
1492 	kset_unregister(devices_kset);
1493 	return -ENOMEM;
1494 }
1495 
1496 static int device_check_offline(struct device *dev, void *not_used)
1497 {
1498 	int ret;
1499 
1500 	ret = device_for_each_child(dev, NULL, device_check_offline);
1501 	if (ret)
1502 		return ret;
1503 
1504 	return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
1505 }
1506 
1507 /**
1508  * device_offline - Prepare the device for hot-removal.
1509  * @dev: Device to be put offline.
1510  *
1511  * Execute the device bus type's .offline() callback, if present, to prepare
1512  * the device for a subsequent hot-removal.  If that succeeds, the device must
1513  * not be used until either it is removed or its bus type's .online() callback
1514  * is executed.
1515  *
1516  * Call under device_hotplug_lock.
1517  */
1518 int device_offline(struct device *dev)
1519 {
1520 	int ret;
1521 
1522 	if (dev->offline_disabled)
1523 		return -EPERM;
1524 
1525 	ret = device_for_each_child(dev, NULL, device_check_offline);
1526 	if (ret)
1527 		return ret;
1528 
1529 	device_lock(dev);
1530 	if (device_supports_offline(dev)) {
1531 		if (dev->offline) {
1532 			ret = 1;
1533 		} else {
1534 			ret = dev->bus->offline(dev);
1535 			if (!ret) {
1536 				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
1537 				dev->offline = true;
1538 			}
1539 		}
1540 	}
1541 	device_unlock(dev);
1542 
1543 	return ret;
1544 }
1545 
1546 /**
1547  * device_online - Put the device back online after successful device_offline().
1548  * @dev: Device to be put back online.
1549  *
1550  * If device_offline() has been successfully executed for @dev, but the device
1551  * has not been removed subsequently, execute its bus type's .online() callback
1552  * to indicate that the device can be used again.
1553  *
1554  * Call under device_hotplug_lock.
1555  */
1556 int device_online(struct device *dev)
1557 {
1558 	int ret = 0;
1559 
1560 	device_lock(dev);
1561 	if (device_supports_offline(dev)) {
1562 		if (dev->offline) {
1563 			ret = dev->bus->online(dev);
1564 			if (!ret) {
1565 				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
1566 				dev->offline = false;
1567 			}
1568 		} else {
1569 			ret = 1;
1570 		}
1571 	}
1572 	device_unlock(dev);
1573 
1574 	return ret;
1575 }
1576 
1577 struct root_device {
1578 	struct device dev;
1579 	struct module *owner;
1580 };
1581 
1582 static inline struct root_device *to_root_device(struct device *d)
1583 {
1584 	return container_of(d, struct root_device, dev);
1585 }
1586 
1587 static void root_device_release(struct device *dev)
1588 {
1589 	kfree(to_root_device(dev));
1590 }
1591 
1592 /**
1593  * __root_device_register - allocate and register a root device
1594  * @name: root device name
1595  * @owner: owner module of the root device, usually THIS_MODULE
1596  *
1597  * This function allocates a root device and registers it
1598  * using device_register(). In order to free the returned
1599  * device, use root_device_unregister().
1600  *
1601  * Root devices are dummy devices which allow other devices
1602  * to be grouped under /sys/devices. Use this function to
1603  * allocate a root device and then use it as the parent of
1604  * any device which should appear under /sys/devices/{name}
1605  *
1606  * The /sys/devices/{name} directory will also contain a
1607  * 'module' symlink which points to the @owner directory
1608  * in sysfs.
1609  *
1610  * Returns &struct device pointer on success, or ERR_PTR() on error.
1611  *
1612  * Note: You probably want to use root_device_register().
1613  */
1614 struct device *__root_device_register(const char *name, struct module *owner)
1615 {
1616 	struct root_device *root;
1617 	int err = -ENOMEM;
1618 
1619 	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
1620 	if (!root)
1621 		return ERR_PTR(err);
1622 
1623 	err = dev_set_name(&root->dev, "%s", name);
1624 	if (err) {
1625 		kfree(root);
1626 		return ERR_PTR(err);
1627 	}
1628 
1629 	root->dev.release = root_device_release;
1630 
1631 	err = device_register(&root->dev);
1632 	if (err) {
1633 		put_device(&root->dev);
1634 		return ERR_PTR(err);
1635 	}
1636 
1637 #ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
1638 	if (owner) {
1639 		struct module_kobject *mk = &owner->mkobj;
1640 
1641 		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
1642 		if (err) {
1643 			device_unregister(&root->dev);
1644 			return ERR_PTR(err);
1645 		}
1646 		root->owner = owner;
1647 	}
1648 #endif
1649 
1650 	return &root->dev;
1651 }
1652 EXPORT_SYMBOL_GPL(__root_device_register);
1653 
1654 /**
1655  * root_device_unregister - unregister and free a root device
1656  * @dev: device going away
1657  *
1658  * This function unregisters and cleans up a device that was created by
1659  * root_device_register().
1660  */
1661 void root_device_unregister(struct device *dev)
1662 {
1663 	struct root_device *root = to_root_device(dev);
1664 
1665 	if (root->owner)
1666 		sysfs_remove_link(&root->dev.kobj, "module");
1667 
1668 	device_unregister(dev);
1669 }
1670 EXPORT_SYMBOL_GPL(root_device_unregister);
1671 
1672 
1673 static void device_create_release(struct device *dev)
1674 {
1675 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
1676 	kfree(dev);
1677 }
1678 
1679 static struct device *
1680 device_create_groups_vargs(struct class *class, struct device *parent,
1681 			   dev_t devt, void *drvdata,
1682 			   const struct attribute_group **groups,
1683 			   const char *fmt, va_list args)
1684 {
1685 	struct device *dev = NULL;
1686 	int retval = -ENODEV;
1687 
1688 	if (class == NULL || IS_ERR(class))
1689 		goto error;
1690 
1691 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1692 	if (!dev) {
1693 		retval = -ENOMEM;
1694 		goto error;
1695 	}
1696 
1697 	device_initialize(dev);
1698 	dev->devt = devt;
1699 	dev->class = class;
1700 	dev->parent = parent;
1701 	dev->groups = groups;
1702 	dev->release = device_create_release;
1703 	dev_set_drvdata(dev, drvdata);
1704 
1705 	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
1706 	if (retval)
1707 		goto error;
1708 
1709 	retval = device_add(dev);
1710 	if (retval)
1711 		goto error;
1712 
1713 	return dev;
1714 
1715 error:
1716 	put_device(dev);
1717 	return ERR_PTR(retval);
1718 }
1719 
1720 /**
1721  * device_create_vargs - creates a device and registers it with sysfs
1722  * @class: pointer to the struct class that this device should be registered to
1723  * @parent: pointer to the parent struct device of this new device, if any
1724  * @devt: the dev_t for the char device to be added
1725  * @drvdata: the data to be added to the device for callbacks
1726  * @fmt: string for the device's name
1727  * @args: va_list for the device's name
1728  *
1729  * This function can be used by char device classes.  A struct device
1730  * will be created in sysfs, registered to the specified class.
1731  *
1732  * A "dev" file will be created, showing the dev_t for the device, if
1733  * the dev_t is not 0,0.
1734  * If a pointer to a parent struct device is passed in, the newly created
1735  * struct device will be a child of that device in sysfs.
1736  * The pointer to the struct device will be returned from the call.
1737  * Any further sysfs files that might be required can be created using this
1738  * pointer.
1739  *
1740  * Returns &struct device pointer on success, or ERR_PTR() on error.
1741  *
1742  * Note: the struct class passed to this function must have previously
1743  * been created with a call to class_create().
1744  */
1745 struct device *device_create_vargs(struct class *class, struct device *parent,
1746 				   dev_t devt, void *drvdata, const char *fmt,
1747 				   va_list args)
1748 {
1749 	return device_create_groups_vargs(class, parent, devt, drvdata, NULL,
1750 					  fmt, args);
1751 }
1752 EXPORT_SYMBOL_GPL(device_create_vargs);
1753 
1754 /**
1755  * device_create - creates a device and registers it with sysfs
1756  * @class: pointer to the struct class that this device should be registered to
1757  * @parent: pointer to the parent struct device of this new device, if any
1758  * @devt: the dev_t for the char device to be added
1759  * @drvdata: the data to be added to the device for callbacks
1760  * @fmt: string for the device's name
1761  *
1762  * This function can be used by char device classes.  A struct device
1763  * will be created in sysfs, registered to the specified class.
1764  *
1765  * A "dev" file will be created, showing the dev_t for the device, if
1766  * the dev_t is not 0,0.
1767  * If a pointer to a parent struct device is passed in, the newly created
1768  * struct device will be a child of that device in sysfs.
1769  * The pointer to the struct device will be returned from the call.
1770  * Any further sysfs files that might be required can be created using this
1771  * pointer.
1772  *
1773  * Returns &struct device pointer on success, or ERR_PTR() on error.
1774  *
1775  * Note: the struct class passed to this function must have previously
1776  * been created with a call to class_create().
1777  */
1778 struct device *device_create(struct class *class, struct device *parent,
1779 			     dev_t devt, void *drvdata, const char *fmt, ...)
1780 {
1781 	va_list vargs;
1782 	struct device *dev;
1783 
1784 	va_start(vargs, fmt);
1785 	dev = device_create_vargs(class, parent, devt, drvdata, fmt, vargs);
1786 	va_end(vargs);
1787 	return dev;
1788 }
1789 EXPORT_SYMBOL_GPL(device_create);
1790 
1791 /**
1792  * device_create_with_groups - creates a device and registers it with sysfs
1793  * @class: pointer to the struct class that this device should be registered to
1794  * @parent: pointer to the parent struct device of this new device, if any
1795  * @devt: the dev_t for the char device to be added
1796  * @drvdata: the data to be added to the device for callbacks
1797  * @groups: NULL-terminated list of attribute groups to be created
1798  * @fmt: string for the device's name
1799  *
1800  * This function can be used by char device classes.  A struct device
1801  * will be created in sysfs, registered to the specified class.
1802  * Additional attributes specified in the groups parameter will also
1803  * be created automatically.
1804  *
1805  * A "dev" file will be created, showing the dev_t for the device, if
1806  * the dev_t is not 0,0.
1807  * If a pointer to a parent struct device is passed in, the newly created
1808  * struct device will be a child of that device in sysfs.
1809  * The pointer to the struct device will be returned from the call.
1810  * Any further sysfs files that might be required can be created using this
1811  * pointer.
1812  *
1813  * Returns &struct device pointer on success, or ERR_PTR() on error.
1814  *
1815  * Note: the struct class passed to this function must have previously
1816  * been created with a call to class_create().
1817  */
1818 struct device *device_create_with_groups(struct class *class,
1819 					 struct device *parent, dev_t devt,
1820 					 void *drvdata,
1821 					 const struct attribute_group **groups,
1822 					 const char *fmt, ...)
1823 {
1824 	va_list vargs;
1825 	struct device *dev;
1826 
1827 	va_start(vargs, fmt);
1828 	dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
1829 					 fmt, vargs);
1830 	va_end(vargs);
1831 	return dev;
1832 }
1833 EXPORT_SYMBOL_GPL(device_create_with_groups);
1834 
1835 static int __match_devt(struct device *dev, const void *data)
1836 {
1837 	const dev_t *devt = data;
1838 
1839 	return dev->devt == *devt;
1840 }
1841 
1842 /**
1843  * device_destroy - removes a device that was created with device_create()
1844  * @class: pointer to the struct class that this device was registered with
1845  * @devt: the dev_t of the device that was previously registered
1846  *
1847  * This call unregisters and cleans up a device that was created with a
1848  * call to device_create().
1849  */
1850 void device_destroy(struct class *class, dev_t devt)
1851 {
1852 	struct device *dev;
1853 
1854 	dev = class_find_device(class, NULL, &devt, __match_devt);
1855 	if (dev) {
1856 		put_device(dev);
1857 		device_unregister(dev);
1858 	}
1859 }
1860 EXPORT_SYMBOL_GPL(device_destroy);
1861 
1862 /**
1863  * device_rename - renames a device
1864  * @dev: the pointer to the struct device to be renamed
1865  * @new_name: the new name of the device
1866  *
1867  * It is the responsibility of the caller to provide mutual
1868  * exclusion between two different calls of device_rename
1869  * on the same device to ensure that new_name is valid and
1870  * won't conflict with other devices.
1871  *
1872  * Note: Don't call this function.  Currently, the networking layer calls this
1873  * function, but that will change.  The following text from Kay Sievers offers
1874  * some insight:
1875  *
1876  * Renaming devices is racy at many levels, symlinks and other stuff are not
1877  * replaced atomically, and you get a "move" uevent, but it's not easy to
1878  * connect the event to the old and new device. Device nodes are not renamed at
1879  * all, there isn't even support for that in the kernel now.
1880  *
1881  * In the meantime, during renaming, your target name might be taken by another
1882  * driver, creating conflicts. Or the old name is taken directly after you
1883  * renamed it -- then you get events for the same DEVPATH, before you even see
1884  * the "move" event. It's just a mess, and nothing new should ever rely on
1885  * kernel device renaming. Besides that, it's not even implemented now for
1886  * other things than (driver-core wise very simple) network devices.
1887  *
1888  * We are currently about to change network renaming in udev to completely
1889  * disallow renaming of devices in the same namespace as the kernel uses,
1890  * because we can't solve the problems properly, that arise with swapping names
1891  * of multiple interfaces without races. Means, renaming of eth[0-9]* will only
1892  * be allowed to some other name than eth[0-9]*, for the aforementioned
1893  * reasons.
1894  *
1895  * Make up a "real" name in the driver before you register anything, or add
1896  * some other attributes for userspace to find the device, or use udev to add
1897  * symlinks -- but never rename kernel devices later, it's a complete mess. We
1898  * don't even want to get into that and try to implement the missing pieces in
1899  * the core. We really have other pieces to fix in the driver core mess. :)
1900  */
1901 int device_rename(struct device *dev, const char *new_name)
1902 {
1903 	struct kobject *kobj = &dev->kobj;
1904 	char *old_device_name = NULL;
1905 	int error;
1906 
1907 	dev = get_device(dev);
1908 	if (!dev)
1909 		return -EINVAL;
1910 
1911 	dev_dbg(dev, "renaming to %s\n", new_name);
1912 
1913 	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
1914 	if (!old_device_name) {
1915 		error = -ENOMEM;
1916 		goto out;
1917 	}
1918 
1919 	if (dev->class) {
1920 		error = sysfs_rename_link_ns(&dev->class->p->subsys.kobj,
1921 					     kobj, old_device_name,
1922 					     new_name, kobject_namespace(kobj));
1923 		if (error)
1924 			goto out;
1925 	}
1926 
1927 	error = kobject_rename(kobj, new_name);
1928 	if (error)
1929 		goto out;
1930 
1931 out:
1932 	put_device(dev);
1933 
1934 	kfree(old_device_name);
1935 
1936 	return error;
1937 }
1938 EXPORT_SYMBOL_GPL(device_rename);
1939 
1940 static int device_move_class_links(struct device *dev,
1941 				   struct device *old_parent,
1942 				   struct device *new_parent)
1943 {
1944 	int error = 0;
1945 
1946 	if (old_parent)
1947 		sysfs_remove_link(&dev->kobj, "device");
1948 	if (new_parent)
1949 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
1950 					  "device");
1951 	return error;
1952 }
1953 
1954 /**
1955  * device_move - moves a device to a new parent
1956  * @dev: the pointer to the struct device to be moved
1957  * @new_parent: the new parent of the device (can by NULL)
1958  * @dpm_order: how to reorder the dpm_list
1959  */
1960 int device_move(struct device *dev, struct device *new_parent,
1961 		enum dpm_order dpm_order)
1962 {
1963 	int error;
1964 	struct device *old_parent;
1965 	struct kobject *new_parent_kobj;
1966 
1967 	dev = get_device(dev);
1968 	if (!dev)
1969 		return -EINVAL;
1970 
1971 	device_pm_lock();
1972 	new_parent = get_device(new_parent);
1973 	new_parent_kobj = get_device_parent(dev, new_parent);
1974 
1975 	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
1976 		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
1977 	error = kobject_move(&dev->kobj, new_parent_kobj);
1978 	if (error) {
1979 		cleanup_glue_dir(dev, new_parent_kobj);
1980 		put_device(new_parent);
1981 		goto out;
1982 	}
1983 	old_parent = dev->parent;
1984 	dev->parent = new_parent;
1985 	if (old_parent)
1986 		klist_remove(&dev->p->knode_parent);
1987 	if (new_parent) {
1988 		klist_add_tail(&dev->p->knode_parent,
1989 			       &new_parent->p->klist_children);
1990 		set_dev_node(dev, dev_to_node(new_parent));
1991 	}
1992 
1993 	if (dev->class) {
1994 		error = device_move_class_links(dev, old_parent, new_parent);
1995 		if (error) {
1996 			/* We ignore errors on cleanup since we're hosed anyway... */
1997 			device_move_class_links(dev, new_parent, old_parent);
1998 			if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
1999 				if (new_parent)
2000 					klist_remove(&dev->p->knode_parent);
2001 				dev->parent = old_parent;
2002 				if (old_parent) {
2003 					klist_add_tail(&dev->p->knode_parent,
2004 						       &old_parent->p->klist_children);
2005 					set_dev_node(dev, dev_to_node(old_parent));
2006 				}
2007 			}
2008 			cleanup_glue_dir(dev, new_parent_kobj);
2009 			put_device(new_parent);
2010 			goto out;
2011 		}
2012 	}
2013 	switch (dpm_order) {
2014 	case DPM_ORDER_NONE:
2015 		break;
2016 	case DPM_ORDER_DEV_AFTER_PARENT:
2017 		device_pm_move_after(dev, new_parent);
2018 		devices_kset_move_after(dev, new_parent);
2019 		break;
2020 	case DPM_ORDER_PARENT_BEFORE_DEV:
2021 		device_pm_move_before(new_parent, dev);
2022 		devices_kset_move_before(new_parent, dev);
2023 		break;
2024 	case DPM_ORDER_DEV_LAST:
2025 		device_pm_move_last(dev);
2026 		devices_kset_move_last(dev);
2027 		break;
2028 	}
2029 
2030 	put_device(old_parent);
2031 out:
2032 	device_pm_unlock();
2033 	put_device(dev);
2034 	return error;
2035 }
2036 EXPORT_SYMBOL_GPL(device_move);
2037 
2038 /**
2039  * device_shutdown - call ->shutdown() on each device to shutdown.
2040  */
2041 void device_shutdown(void)
2042 {
2043 	struct device *dev, *parent;
2044 
2045 	spin_lock(&devices_kset->list_lock);
2046 	/*
2047 	 * Walk the devices list backward, shutting down each in turn.
2048 	 * Beware that device unplug events may also start pulling
2049 	 * devices offline, even as the system is shutting down.
2050 	 */
2051 	while (!list_empty(&devices_kset->list)) {
2052 		dev = list_entry(devices_kset->list.prev, struct device,
2053 				kobj.entry);
2054 
2055 		/*
2056 		 * hold reference count of device's parent to
2057 		 * prevent it from being freed because parent's
2058 		 * lock is to be held
2059 		 */
2060 		parent = get_device(dev->parent);
2061 		get_device(dev);
2062 		/*
2063 		 * Make sure the device is off the kset list, in the
2064 		 * event that dev->*->shutdown() doesn't remove it.
2065 		 */
2066 		list_del_init(&dev->kobj.entry);
2067 		spin_unlock(&devices_kset->list_lock);
2068 
2069 		/* hold lock to avoid race with probe/release */
2070 		if (parent)
2071 			device_lock(parent);
2072 		device_lock(dev);
2073 
2074 		/* Don't allow any more runtime suspends */
2075 		pm_runtime_get_noresume(dev);
2076 		pm_runtime_barrier(dev);
2077 
2078 		if (dev->bus && dev->bus->shutdown) {
2079 			if (initcall_debug)
2080 				dev_info(dev, "shutdown\n");
2081 			dev->bus->shutdown(dev);
2082 		} else if (dev->driver && dev->driver->shutdown) {
2083 			if (initcall_debug)
2084 				dev_info(dev, "shutdown\n");
2085 			dev->driver->shutdown(dev);
2086 		}
2087 
2088 		device_unlock(dev);
2089 		if (parent)
2090 			device_unlock(parent);
2091 
2092 		put_device(dev);
2093 		put_device(parent);
2094 
2095 		spin_lock(&devices_kset->list_lock);
2096 	}
2097 	spin_unlock(&devices_kset->list_lock);
2098 }
2099 
2100 /*
2101  * Device logging functions
2102  */
2103 
2104 #ifdef CONFIG_PRINTK
2105 static int
2106 create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
2107 {
2108 	const char *subsys;
2109 	size_t pos = 0;
2110 
2111 	if (dev->class)
2112 		subsys = dev->class->name;
2113 	else if (dev->bus)
2114 		subsys = dev->bus->name;
2115 	else
2116 		return 0;
2117 
2118 	pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);
2119 	if (pos >= hdrlen)
2120 		goto overflow;
2121 
2122 	/*
2123 	 * Add device identifier DEVICE=:
2124 	 *   b12:8         block dev_t
2125 	 *   c127:3        char dev_t
2126 	 *   n8            netdev ifindex
2127 	 *   +sound:card0  subsystem:devname
2128 	 */
2129 	if (MAJOR(dev->devt)) {
2130 		char c;
2131 
2132 		if (strcmp(subsys, "block") == 0)
2133 			c = 'b';
2134 		else
2135 			c = 'c';
2136 		pos++;
2137 		pos += snprintf(hdr + pos, hdrlen - pos,
2138 				"DEVICE=%c%u:%u",
2139 				c, MAJOR(dev->devt), MINOR(dev->devt));
2140 	} else if (strcmp(subsys, "net") == 0) {
2141 		struct net_device *net = to_net_dev(dev);
2142 
2143 		pos++;
2144 		pos += snprintf(hdr + pos, hdrlen - pos,
2145 				"DEVICE=n%u", net->ifindex);
2146 	} else {
2147 		pos++;
2148 		pos += snprintf(hdr + pos, hdrlen - pos,
2149 				"DEVICE=+%s:%s", subsys, dev_name(dev));
2150 	}
2151 
2152 	if (pos >= hdrlen)
2153 		goto overflow;
2154 
2155 	return pos;
2156 
2157 overflow:
2158 	dev_WARN(dev, "device/subsystem name too long");
2159 	return 0;
2160 }
2161 
2162 int dev_vprintk_emit(int level, const struct device *dev,
2163 		     const char *fmt, va_list args)
2164 {
2165 	char hdr[128];
2166 	size_t hdrlen;
2167 
2168 	hdrlen = create_syslog_header(dev, hdr, sizeof(hdr));
2169 
2170 	return vprintk_emit(0, level, hdrlen ? hdr : NULL, hdrlen, fmt, args);
2171 }
2172 EXPORT_SYMBOL(dev_vprintk_emit);
2173 
2174 int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
2175 {
2176 	va_list args;
2177 	int r;
2178 
2179 	va_start(args, fmt);
2180 
2181 	r = dev_vprintk_emit(level, dev, fmt, args);
2182 
2183 	va_end(args);
2184 
2185 	return r;
2186 }
2187 EXPORT_SYMBOL(dev_printk_emit);
2188 
2189 static void __dev_printk(const char *level, const struct device *dev,
2190 			struct va_format *vaf)
2191 {
2192 	if (dev)
2193 		dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
2194 				dev_driver_string(dev), dev_name(dev), vaf);
2195 	else
2196 		printk("%s(NULL device *): %pV", level, vaf);
2197 }
2198 
2199 void dev_printk(const char *level, const struct device *dev,
2200 		const char *fmt, ...)
2201 {
2202 	struct va_format vaf;
2203 	va_list args;
2204 
2205 	va_start(args, fmt);
2206 
2207 	vaf.fmt = fmt;
2208 	vaf.va = &args;
2209 
2210 	__dev_printk(level, dev, &vaf);
2211 
2212 	va_end(args);
2213 }
2214 EXPORT_SYMBOL(dev_printk);
2215 
2216 #define define_dev_printk_level(func, kern_level)		\
2217 void func(const struct device *dev, const char *fmt, ...)	\
2218 {								\
2219 	struct va_format vaf;					\
2220 	va_list args;						\
2221 								\
2222 	va_start(args, fmt);					\
2223 								\
2224 	vaf.fmt = fmt;						\
2225 	vaf.va = &args;						\
2226 								\
2227 	__dev_printk(kern_level, dev, &vaf);			\
2228 								\
2229 	va_end(args);						\
2230 }								\
2231 EXPORT_SYMBOL(func);
2232 
2233 define_dev_printk_level(dev_emerg, KERN_EMERG);
2234 define_dev_printk_level(dev_alert, KERN_ALERT);
2235 define_dev_printk_level(dev_crit, KERN_CRIT);
2236 define_dev_printk_level(dev_err, KERN_ERR);
2237 define_dev_printk_level(dev_warn, KERN_WARNING);
2238 define_dev_printk_level(dev_notice, KERN_NOTICE);
2239 define_dev_printk_level(_dev_info, KERN_INFO);
2240 
2241 #endif
2242 
2243 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
2244 {
2245 	return fwnode && !IS_ERR(fwnode->secondary);
2246 }
2247 
2248 /**
2249  * set_primary_fwnode - Change the primary firmware node of a given device.
2250  * @dev: Device to handle.
2251  * @fwnode: New primary firmware node of the device.
2252  *
2253  * Set the device's firmware node pointer to @fwnode, but if a secondary
2254  * firmware node of the device is present, preserve it.
2255  */
2256 void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
2257 {
2258 	if (fwnode) {
2259 		struct fwnode_handle *fn = dev->fwnode;
2260 
2261 		if (fwnode_is_primary(fn))
2262 			fn = fn->secondary;
2263 
2264 		if (fn) {
2265 			WARN_ON(fwnode->secondary);
2266 			fwnode->secondary = fn;
2267 		}
2268 		dev->fwnode = fwnode;
2269 	} else {
2270 		dev->fwnode = fwnode_is_primary(dev->fwnode) ?
2271 			dev->fwnode->secondary : NULL;
2272 	}
2273 }
2274 EXPORT_SYMBOL_GPL(set_primary_fwnode);
2275 
2276 /**
2277  * set_secondary_fwnode - Change the secondary firmware node of a given device.
2278  * @dev: Device to handle.
2279  * @fwnode: New secondary firmware node of the device.
2280  *
2281  * If a primary firmware node of the device is present, set its secondary
2282  * pointer to @fwnode.  Otherwise, set the device's firmware node pointer to
2283  * @fwnode.
2284  */
2285 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
2286 {
2287 	if (fwnode)
2288 		fwnode->secondary = ERR_PTR(-ENODEV);
2289 
2290 	if (fwnode_is_primary(dev->fwnode))
2291 		dev->fwnode->secondary = fwnode;
2292 	else
2293 		dev->fwnode = fwnode;
2294 }
2295