xref: /openbmc/linux/drivers/base/core.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/init.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/string.h>
19 #include <linux/kdev_t.h>
20 #include <linux/notifier.h>
21 
22 #include <asm/semaphore.h>
23 
24 #include "base.h"
25 #include "power/power.h"
26 
27 int (*platform_notify)(struct device * dev) = NULL;
28 int (*platform_notify_remove)(struct device * dev) = NULL;
29 
30 /*
31  * sysfs bindings for devices.
32  */
33 
34 /**
35  * dev_driver_string - Return a device's driver name, if at all possible
36  * @dev: struct device to get the name of
37  *
38  * Will return the device's driver's name if it is bound to a device.  If
39  * the device is not bound to a device, it will return the name of the bus
40  * it is attached to.  If it is not attached to a bus either, an empty
41  * string will be returned.
42  */
43 const char *dev_driver_string(struct device *dev)
44 {
45 	return dev->driver ? dev->driver->name :
46 			(dev->bus ? dev->bus->name :
47 			(dev->class ? dev->class->name : ""));
48 }
49 EXPORT_SYMBOL(dev_driver_string);
50 
51 #define to_dev(obj) container_of(obj, struct device, kobj)
52 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
53 
54 static ssize_t
55 dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
56 {
57 	struct device_attribute * dev_attr = to_dev_attr(attr);
58 	struct device * dev = to_dev(kobj);
59 	ssize_t ret = -EIO;
60 
61 	if (dev_attr->show)
62 		ret = dev_attr->show(dev, dev_attr, buf);
63 	return ret;
64 }
65 
66 static ssize_t
67 dev_attr_store(struct kobject * kobj, struct attribute * attr,
68 	       const char * buf, size_t count)
69 {
70 	struct device_attribute * dev_attr = to_dev_attr(attr);
71 	struct device * dev = to_dev(kobj);
72 	ssize_t ret = -EIO;
73 
74 	if (dev_attr->store)
75 		ret = dev_attr->store(dev, dev_attr, buf, count);
76 	return ret;
77 }
78 
79 static struct sysfs_ops dev_sysfs_ops = {
80 	.show	= dev_attr_show,
81 	.store	= dev_attr_store,
82 };
83 
84 
85 /**
86  *	device_release - free device structure.
87  *	@kobj:	device's kobject.
88  *
89  *	This is called once the reference count for the object
90  *	reaches 0. We forward the call to the device's release
91  *	method, which should handle actually freeing the structure.
92  */
93 static void device_release(struct kobject * kobj)
94 {
95 	struct device * dev = to_dev(kobj);
96 
97 	if (dev->release)
98 		dev->release(dev);
99 	else if (dev->type && dev->type->release)
100 		dev->type->release(dev);
101 	else if (dev->class && dev->class->dev_release)
102 		dev->class->dev_release(dev);
103 	else {
104 		printk(KERN_ERR "Device '%s' does not have a release() function, "
105 			"it is broken and must be fixed.\n",
106 			dev->bus_id);
107 		WARN_ON(1);
108 	}
109 }
110 
111 static struct kobj_type ktype_device = {
112 	.release	= device_release,
113 	.sysfs_ops	= &dev_sysfs_ops,
114 };
115 
116 
117 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
118 {
119 	struct kobj_type *ktype = get_ktype(kobj);
120 
121 	if (ktype == &ktype_device) {
122 		struct device *dev = to_dev(kobj);
123 		if (dev->uevent_suppress)
124 			return 0;
125 		if (dev->bus)
126 			return 1;
127 		if (dev->class)
128 			return 1;
129 	}
130 	return 0;
131 }
132 
133 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
134 {
135 	struct device *dev = to_dev(kobj);
136 
137 	if (dev->bus)
138 		return dev->bus->name;
139 	if (dev->class)
140 		return dev->class->name;
141 	return NULL;
142 }
143 
144 static int dev_uevent(struct kset *kset, struct kobject *kobj, char **envp,
145 			int num_envp, char *buffer, int buffer_size)
146 {
147 	struct device *dev = to_dev(kobj);
148 	int i = 0;
149 	int length = 0;
150 	int retval = 0;
151 
152 	/* add the major/minor if present */
153 	if (MAJOR(dev->devt)) {
154 		add_uevent_var(envp, num_envp, &i,
155 			       buffer, buffer_size, &length,
156 			       "MAJOR=%u", MAJOR(dev->devt));
157 		add_uevent_var(envp, num_envp, &i,
158 			       buffer, buffer_size, &length,
159 			       "MINOR=%u", MINOR(dev->devt));
160 	}
161 
162 	if (dev->type && dev->type->name)
163 		add_uevent_var(envp, num_envp, &i,
164 			       buffer, buffer_size, &length,
165 			       "DEVTYPE=%s", dev->type->name);
166 
167 	if (dev->driver)
168 		add_uevent_var(envp, num_envp, &i,
169 			       buffer, buffer_size, &length,
170 			       "DRIVER=%s", dev->driver->name);
171 
172 #ifdef CONFIG_SYSFS_DEPRECATED
173 	if (dev->class) {
174 		struct device *parent = dev->parent;
175 
176 		/* find first bus device in parent chain */
177 		while (parent && !parent->bus)
178 			parent = parent->parent;
179 		if (parent && parent->bus) {
180 			const char *path;
181 
182 			path = kobject_get_path(&parent->kobj, GFP_KERNEL);
183 			add_uevent_var(envp, num_envp, &i,
184 				       buffer, buffer_size, &length,
185 				       "PHYSDEVPATH=%s", path);
186 			kfree(path);
187 
188 			add_uevent_var(envp, num_envp, &i,
189 				       buffer, buffer_size, &length,
190 				       "PHYSDEVBUS=%s", parent->bus->name);
191 
192 			if (parent->driver)
193 				add_uevent_var(envp, num_envp, &i,
194 					       buffer, buffer_size, &length,
195 					       "PHYSDEVDRIVER=%s", parent->driver->name);
196 		}
197 	} else if (dev->bus) {
198 		add_uevent_var(envp, num_envp, &i,
199 			       buffer, buffer_size, &length,
200 			       "PHYSDEVBUS=%s", dev->bus->name);
201 
202 		if (dev->driver)
203 			add_uevent_var(envp, num_envp, &i,
204 				       buffer, buffer_size, &length,
205 				       "PHYSDEVDRIVER=%s", dev->driver->name);
206 	}
207 #endif
208 
209 	/* terminate, set to next free slot, shrink available space */
210 	envp[i] = NULL;
211 	envp = &envp[i];
212 	num_envp -= i;
213 	buffer = &buffer[length];
214 	buffer_size -= length;
215 
216 	if (dev->bus && dev->bus->uevent) {
217 		/* have the bus specific function add its stuff */
218 		retval = dev->bus->uevent(dev, envp, num_envp, buffer, buffer_size);
219 		if (retval)
220 			pr_debug ("%s: bus uevent() returned %d\n",
221 				  __FUNCTION__, retval);
222 	}
223 
224 	if (dev->class && dev->class->dev_uevent) {
225 		/* have the class specific function add its stuff */
226 		retval = dev->class->dev_uevent(dev, envp, num_envp, buffer, buffer_size);
227 		if (retval)
228 			pr_debug("%s: class uevent() returned %d\n",
229 				 __FUNCTION__, retval);
230 	}
231 
232 	if (dev->type && dev->type->uevent) {
233 		/* have the device type specific fuction add its stuff */
234 		retval = dev->type->uevent(dev, envp, num_envp, buffer, buffer_size);
235 		if (retval)
236 			pr_debug("%s: dev_type uevent() returned %d\n",
237 				 __FUNCTION__, retval);
238 	}
239 
240 	return retval;
241 }
242 
243 static struct kset_uevent_ops device_uevent_ops = {
244 	.filter =	dev_uevent_filter,
245 	.name =		dev_uevent_name,
246 	.uevent =	dev_uevent,
247 };
248 
249 static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
250 			   char *buf)
251 {
252 	struct kobject *top_kobj;
253 	struct kset *kset;
254 	char *envp[32];
255 	char *data = NULL;
256 	char *pos;
257 	int i;
258 	size_t count = 0;
259 	int retval;
260 
261 	/* search the kset, the device belongs to */
262 	top_kobj = &dev->kobj;
263 	if (!top_kobj->kset && top_kobj->parent) {
264 		do {
265 			top_kobj = top_kobj->parent;
266 		} while (!top_kobj->kset && top_kobj->parent);
267 	}
268 	if (!top_kobj->kset)
269 		goto out;
270 	kset = top_kobj->kset;
271 	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
272 		goto out;
273 
274 	/* respect filter */
275 	if (kset->uevent_ops && kset->uevent_ops->filter)
276 		if (!kset->uevent_ops->filter(kset, &dev->kobj))
277 			goto out;
278 
279 	data = (char *)get_zeroed_page(GFP_KERNEL);
280 	if (!data)
281 		return -ENOMEM;
282 
283 	/* let the kset specific function add its keys */
284 	pos = data;
285 	retval = kset->uevent_ops->uevent(kset, &dev->kobj,
286 					  envp, ARRAY_SIZE(envp),
287 					  pos, PAGE_SIZE);
288 	if (retval)
289 		goto out;
290 
291 	/* copy keys to file */
292 	for (i = 0; envp[i]; i++) {
293 		pos = &buf[count];
294 		count += sprintf(pos, "%s\n", envp[i]);
295 	}
296 out:
297 	free_page((unsigned long)data);
298 	return count;
299 }
300 
301 static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
302 			    const char *buf, size_t count)
303 {
304 	if (memcmp(buf, "add", 3) != 0)
305 		dev_err(dev, "uevent: unsupported action-string; this will "
306 			"be ignored in a future kernel version");
307 	kobject_uevent(&dev->kobj, KOBJ_ADD);
308 	return count;
309 }
310 
311 static int device_add_attributes(struct device *dev,
312 				 struct device_attribute *attrs)
313 {
314 	int error = 0;
315 	int i;
316 
317 	if (attrs) {
318 		for (i = 0; attr_name(attrs[i]); i++) {
319 			error = device_create_file(dev, &attrs[i]);
320 			if (error)
321 				break;
322 		}
323 		if (error)
324 			while (--i >= 0)
325 				device_remove_file(dev, &attrs[i]);
326 	}
327 	return error;
328 }
329 
330 static void device_remove_attributes(struct device *dev,
331 				     struct device_attribute *attrs)
332 {
333 	int i;
334 
335 	if (attrs)
336 		for (i = 0; attr_name(attrs[i]); i++)
337 			device_remove_file(dev, &attrs[i]);
338 }
339 
340 static int device_add_groups(struct device *dev,
341 			     struct attribute_group **groups)
342 {
343 	int error = 0;
344 	int i;
345 
346 	if (groups) {
347 		for (i = 0; groups[i]; i++) {
348 			error = sysfs_create_group(&dev->kobj, groups[i]);
349 			if (error) {
350 				while (--i >= 0)
351 					sysfs_remove_group(&dev->kobj, groups[i]);
352 				break;
353 			}
354 		}
355 	}
356 	return error;
357 }
358 
359 static void device_remove_groups(struct device *dev,
360 				 struct attribute_group **groups)
361 {
362 	int i;
363 
364 	if (groups)
365 		for (i = 0; groups[i]; i++)
366 			sysfs_remove_group(&dev->kobj, groups[i]);
367 }
368 
369 static int device_add_attrs(struct device *dev)
370 {
371 	struct class *class = dev->class;
372 	struct device_type *type = dev->type;
373 	int error;
374 
375 	if (class) {
376 		error = device_add_attributes(dev, class->dev_attrs);
377 		if (error)
378 			return error;
379 	}
380 
381 	if (type) {
382 		error = device_add_groups(dev, type->groups);
383 		if (error)
384 			goto err_remove_class_attrs;
385 	}
386 
387 	error = device_add_groups(dev, dev->groups);
388 	if (error)
389 		goto err_remove_type_groups;
390 
391 	return 0;
392 
393  err_remove_type_groups:
394 	if (type)
395 		device_remove_groups(dev, type->groups);
396  err_remove_class_attrs:
397 	if (class)
398 		device_remove_attributes(dev, class->dev_attrs);
399 
400 	return error;
401 }
402 
403 static void device_remove_attrs(struct device *dev)
404 {
405 	struct class *class = dev->class;
406 	struct device_type *type = dev->type;
407 
408 	device_remove_groups(dev, dev->groups);
409 
410 	if (type)
411 		device_remove_groups(dev, type->groups);
412 
413 	if (class)
414 		device_remove_attributes(dev, class->dev_attrs);
415 }
416 
417 
418 static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
419 			char *buf)
420 {
421 	return print_dev_t(buf, dev->devt);
422 }
423 
424 /*
425  *	devices_subsys - structure to be registered with kobject core.
426  */
427 
428 decl_subsys(devices, &ktype_device, &device_uevent_ops);
429 
430 
431 /**
432  *	device_create_file - create sysfs attribute file for device.
433  *	@dev:	device.
434  *	@attr:	device attribute descriptor.
435  */
436 
437 int device_create_file(struct device * dev, struct device_attribute * attr)
438 {
439 	int error = 0;
440 	if (get_device(dev)) {
441 		error = sysfs_create_file(&dev->kobj, &attr->attr);
442 		put_device(dev);
443 	}
444 	return error;
445 }
446 
447 /**
448  *	device_remove_file - remove sysfs attribute file.
449  *	@dev:	device.
450  *	@attr:	device attribute descriptor.
451  */
452 
453 void device_remove_file(struct device * dev, struct device_attribute * attr)
454 {
455 	if (get_device(dev)) {
456 		sysfs_remove_file(&dev->kobj, &attr->attr);
457 		put_device(dev);
458 	}
459 }
460 
461 /**
462  * device_create_bin_file - create sysfs binary attribute file for device.
463  * @dev: device.
464  * @attr: device binary attribute descriptor.
465  */
466 int device_create_bin_file(struct device *dev, struct bin_attribute *attr)
467 {
468 	int error = -EINVAL;
469 	if (dev)
470 		error = sysfs_create_bin_file(&dev->kobj, attr);
471 	return error;
472 }
473 EXPORT_SYMBOL_GPL(device_create_bin_file);
474 
475 /**
476  * device_remove_bin_file - remove sysfs binary attribute file
477  * @dev: device.
478  * @attr: device binary attribute descriptor.
479  */
480 void device_remove_bin_file(struct device *dev, struct bin_attribute *attr)
481 {
482 	if (dev)
483 		sysfs_remove_bin_file(&dev->kobj, attr);
484 }
485 EXPORT_SYMBOL_GPL(device_remove_bin_file);
486 
487 /**
488  * device_schedule_callback_owner - helper to schedule a callback for a device
489  * @dev: device.
490  * @func: callback function to invoke later.
491  * @owner: module owning the callback routine
492  *
493  * Attribute methods must not unregister themselves or their parent device
494  * (which would amount to the same thing).  Attempts to do so will deadlock,
495  * since unregistration is mutually exclusive with driver callbacks.
496  *
497  * Instead methods can call this routine, which will attempt to allocate
498  * and schedule a workqueue request to call back @func with @dev as its
499  * argument in the workqueue's process context.  @dev will be pinned until
500  * @func returns.
501  *
502  * This routine is usually called via the inline device_schedule_callback(),
503  * which automatically sets @owner to THIS_MODULE.
504  *
505  * Returns 0 if the request was submitted, -ENOMEM if storage could not
506  * be allocated, -ENODEV if a reference to @owner isn't available.
507  *
508  * NOTE: This routine won't work if CONFIG_SYSFS isn't set!  It uses an
509  * underlying sysfs routine (since it is intended for use by attribute
510  * methods), and if sysfs isn't available you'll get nothing but -ENOSYS.
511  */
512 int device_schedule_callback_owner(struct device *dev,
513 		void (*func)(struct device *), struct module *owner)
514 {
515 	return sysfs_schedule_callback(&dev->kobj,
516 			(void (*)(void *)) func, dev, owner);
517 }
518 EXPORT_SYMBOL_GPL(device_schedule_callback_owner);
519 
520 static void klist_children_get(struct klist_node *n)
521 {
522 	struct device *dev = container_of(n, struct device, knode_parent);
523 
524 	get_device(dev);
525 }
526 
527 static void klist_children_put(struct klist_node *n)
528 {
529 	struct device *dev = container_of(n, struct device, knode_parent);
530 
531 	put_device(dev);
532 }
533 
534 
535 /**
536  *	device_initialize - init device structure.
537  *	@dev:	device.
538  *
539  *	This prepares the device for use by other layers,
540  *	including adding it to the device hierarchy.
541  *	It is the first half of device_register(), if called by
542  *	that, though it can also be called separately, so one
543  *	may use @dev's fields (e.g. the refcount).
544  */
545 
546 void device_initialize(struct device *dev)
547 {
548 	kobj_set_kset_s(dev, devices_subsys);
549 	kobject_init(&dev->kobj);
550 	klist_init(&dev->klist_children, klist_children_get,
551 		   klist_children_put);
552 	INIT_LIST_HEAD(&dev->dma_pools);
553 	INIT_LIST_HEAD(&dev->node);
554 	init_MUTEX(&dev->sem);
555 	spin_lock_init(&dev->devres_lock);
556 	INIT_LIST_HEAD(&dev->devres_head);
557 	device_init_wakeup(dev, 0);
558 	set_dev_node(dev, -1);
559 }
560 
561 #ifdef CONFIG_SYSFS_DEPRECATED
562 static struct kobject * get_device_parent(struct device *dev,
563 					  struct device *parent)
564 {
565 	/* Set the parent to the class, not the parent device */
566 	/* this keeps sysfs from having a symlink to make old udevs happy */
567 	if (dev->class)
568 		return &dev->class->subsys.kobj;
569 	else if (parent)
570 		return &parent->kobj;
571 
572 	return NULL;
573 }
574 #else
575 static struct kobject *virtual_device_parent(struct device *dev)
576 {
577 	static struct kobject *virtual_dir = NULL;
578 
579 	if (!virtual_dir)
580 		virtual_dir = kobject_add_dir(&devices_subsys.kobj, "virtual");
581 
582 	return virtual_dir;
583 }
584 
585 static struct kobject * get_device_parent(struct device *dev,
586 					  struct device *parent)
587 {
588 	if (dev->class) {
589 		struct kobject *kobj = NULL;
590 		struct kobject *parent_kobj;
591 		struct kobject *k;
592 
593 		/*
594 		 * If we have no parent, we live in "virtual".
595 		 * Class-devices with a bus-device as parent, live
596 		 * in a class-directory to prevent namespace collisions.
597 		 */
598 		if (parent == NULL)
599 			parent_kobj = virtual_device_parent(dev);
600 		else if (parent->class)
601 			return &parent->kobj;
602 		else
603 			parent_kobj = &parent->kobj;
604 
605 		/* find our class-directory at the parent and reference it */
606 		spin_lock(&dev->class->class_dirs.list_lock);
607 		list_for_each_entry(k, &dev->class->class_dirs.list, entry)
608 			if (k->parent == parent_kobj) {
609 				kobj = kobject_get(k);
610 				break;
611 			}
612 		spin_unlock(&dev->class->class_dirs.list_lock);
613 		if (kobj)
614 			return kobj;
615 
616 		/* or create a new class-directory at the parent device */
617 		return kobject_kset_add_dir(&dev->class->class_dirs,
618 					    parent_kobj, dev->class->name);
619 	}
620 
621 	if (parent)
622 		return &parent->kobj;
623 	return NULL;
624 }
625 #endif
626 
627 static int setup_parent(struct device *dev, struct device *parent)
628 {
629 	struct kobject *kobj;
630 	kobj = get_device_parent(dev, parent);
631 	if (IS_ERR(kobj))
632 		return PTR_ERR(kobj);
633 	if (kobj)
634 		dev->kobj.parent = kobj;
635 	return 0;
636 }
637 
638 /**
639  *	device_add - add device to device hierarchy.
640  *	@dev:	device.
641  *
642  *	This is part 2 of device_register(), though may be called
643  *	separately _iff_ device_initialize() has been called separately.
644  *
645  *	This adds it to the kobject hierarchy via kobject_add(), adds it
646  *	to the global and sibling lists for the device, then
647  *	adds it to the other relevant subsystems of the driver model.
648  */
649 int device_add(struct device *dev)
650 {
651 	struct device *parent = NULL;
652 	char *class_name = NULL;
653 	struct class_interface *class_intf;
654 	int error = -EINVAL;
655 
656 	dev = get_device(dev);
657 	if (!dev || !strlen(dev->bus_id))
658 		goto Error;
659 
660 	pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
661 
662 	parent = get_device(dev->parent);
663 	error = setup_parent(dev, parent);
664 	if (error)
665 		goto Error;
666 
667 	/* first, register with generic layer. */
668 	kobject_set_name(&dev->kobj, "%s", dev->bus_id);
669 	error = kobject_add(&dev->kobj);
670 	if (error)
671 		goto Error;
672 
673 	/* notify platform of device entry */
674 	if (platform_notify)
675 		platform_notify(dev);
676 
677 	/* notify clients of device entry (new way) */
678 	if (dev->bus)
679 		blocking_notifier_call_chain(&dev->bus->bus_notifier,
680 					     BUS_NOTIFY_ADD_DEVICE, dev);
681 
682 	dev->uevent_attr.attr.name = "uevent";
683 	dev->uevent_attr.attr.mode = S_IRUGO | S_IWUSR;
684 	if (dev->driver)
685 		dev->uevent_attr.attr.owner = dev->driver->owner;
686 	dev->uevent_attr.store = store_uevent;
687 	dev->uevent_attr.show = show_uevent;
688 	error = device_create_file(dev, &dev->uevent_attr);
689 	if (error)
690 		goto attrError;
691 
692 	if (MAJOR(dev->devt)) {
693 		struct device_attribute *attr;
694 		attr = kzalloc(sizeof(*attr), GFP_KERNEL);
695 		if (!attr) {
696 			error = -ENOMEM;
697 			goto ueventattrError;
698 		}
699 		attr->attr.name = "dev";
700 		attr->attr.mode = S_IRUGO;
701 		if (dev->driver)
702 			attr->attr.owner = dev->driver->owner;
703 		attr->show = show_dev;
704 		error = device_create_file(dev, attr);
705 		if (error) {
706 			kfree(attr);
707 			goto ueventattrError;
708 		}
709 
710 		dev->devt_attr = attr;
711 	}
712 
713 	if (dev->class) {
714 		sysfs_create_link(&dev->kobj, &dev->class->subsys.kobj,
715 				  "subsystem");
716 		/* If this is not a "fake" compatible device, then create the
717 		 * symlink from the class to the device. */
718 		if (dev->kobj.parent != &dev->class->subsys.kobj)
719 			sysfs_create_link(&dev->class->subsys.kobj,
720 					  &dev->kobj, dev->bus_id);
721 		if (parent) {
722 			sysfs_create_link(&dev->kobj, &dev->parent->kobj,
723 							"device");
724 #ifdef CONFIG_SYSFS_DEPRECATED
725 			class_name = make_class_name(dev->class->name,
726 							&dev->kobj);
727 			if (class_name)
728 				sysfs_create_link(&dev->parent->kobj,
729 						  &dev->kobj, class_name);
730 #endif
731 		}
732 	}
733 
734 	if ((error = device_add_attrs(dev)))
735 		goto AttrsError;
736 	if ((error = device_pm_add(dev)))
737 		goto PMError;
738 	if ((error = bus_add_device(dev)))
739 		goto BusError;
740 	kobject_uevent(&dev->kobj, KOBJ_ADD);
741 	bus_attach_device(dev);
742 	if (parent)
743 		klist_add_tail(&dev->knode_parent, &parent->klist_children);
744 
745 	if (dev->class) {
746 		down(&dev->class->sem);
747 		/* tie the class to the device */
748 		list_add_tail(&dev->node, &dev->class->devices);
749 
750 		/* notify any interfaces that the device is here */
751 		list_for_each_entry(class_intf, &dev->class->interfaces, node)
752 			if (class_intf->add_dev)
753 				class_intf->add_dev(dev, class_intf);
754 		up(&dev->class->sem);
755 	}
756  Done:
757 	kfree(class_name);
758 	put_device(dev);
759 	return error;
760  BusError:
761 	device_pm_remove(dev);
762  PMError:
763 	if (dev->bus)
764 		blocking_notifier_call_chain(&dev->bus->bus_notifier,
765 					     BUS_NOTIFY_DEL_DEVICE, dev);
766 	device_remove_attrs(dev);
767  AttrsError:
768 	if (dev->devt_attr) {
769 		device_remove_file(dev, dev->devt_attr);
770 		kfree(dev->devt_attr);
771 	}
772 
773 	if (dev->class) {
774 		sysfs_remove_link(&dev->kobj, "subsystem");
775 		/* If this is not a "fake" compatible device, remove the
776 		 * symlink from the class to the device. */
777 		if (dev->kobj.parent != &dev->class->subsys.kobj)
778 			sysfs_remove_link(&dev->class->subsys.kobj,
779 					  dev->bus_id);
780 		if (parent) {
781 #ifdef CONFIG_SYSFS_DEPRECATED
782 			char *class_name = make_class_name(dev->class->name,
783 							   &dev->kobj);
784 			if (class_name)
785 				sysfs_remove_link(&dev->parent->kobj,
786 						  class_name);
787 			kfree(class_name);
788 #endif
789 			sysfs_remove_link(&dev->kobj, "device");
790 		}
791 	}
792  ueventattrError:
793 	device_remove_file(dev, &dev->uevent_attr);
794  attrError:
795 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
796 	kobject_del(&dev->kobj);
797  Error:
798 	if (parent)
799 		put_device(parent);
800 	goto Done;
801 }
802 
803 
804 /**
805  *	device_register - register a device with the system.
806  *	@dev:	pointer to the device structure
807  *
808  *	This happens in two clean steps - initialize the device
809  *	and add it to the system. The two steps can be called
810  *	separately, but this is the easiest and most common.
811  *	I.e. you should only call the two helpers separately if
812  *	have a clearly defined need to use and refcount the device
813  *	before it is added to the hierarchy.
814  */
815 
816 int device_register(struct device *dev)
817 {
818 	device_initialize(dev);
819 	return device_add(dev);
820 }
821 
822 
823 /**
824  *	get_device - increment reference count for device.
825  *	@dev:	device.
826  *
827  *	This simply forwards the call to kobject_get(), though
828  *	we do take care to provide for the case that we get a NULL
829  *	pointer passed in.
830  */
831 
832 struct device * get_device(struct device * dev)
833 {
834 	return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
835 }
836 
837 
838 /**
839  *	put_device - decrement reference count.
840  *	@dev:	device in question.
841  */
842 void put_device(struct device * dev)
843 {
844 	if (dev)
845 		kobject_put(&dev->kobj);
846 }
847 
848 
849 /**
850  *	device_del - delete device from system.
851  *	@dev:	device.
852  *
853  *	This is the first part of the device unregistration
854  *	sequence. This removes the device from the lists we control
855  *	from here, has it removed from the other driver model
856  *	subsystems it was added to in device_add(), and removes it
857  *	from the kobject hierarchy.
858  *
859  *	NOTE: this should be called manually _iff_ device_add() was
860  *	also called manually.
861  */
862 
863 void device_del(struct device * dev)
864 {
865 	struct device * parent = dev->parent;
866 	struct class_interface *class_intf;
867 
868 	if (parent)
869 		klist_del(&dev->knode_parent);
870 	if (dev->devt_attr) {
871 		device_remove_file(dev, dev->devt_attr);
872 		kfree(dev->devt_attr);
873 	}
874 	if (dev->class) {
875 		sysfs_remove_link(&dev->kobj, "subsystem");
876 		/* If this is not a "fake" compatible device, remove the
877 		 * symlink from the class to the device. */
878 		if (dev->kobj.parent != &dev->class->subsys.kobj)
879 			sysfs_remove_link(&dev->class->subsys.kobj,
880 					  dev->bus_id);
881 		if (parent) {
882 #ifdef CONFIG_SYSFS_DEPRECATED
883 			char *class_name = make_class_name(dev->class->name,
884 							   &dev->kobj);
885 			if (class_name)
886 				sysfs_remove_link(&dev->parent->kobj,
887 						  class_name);
888 			kfree(class_name);
889 #endif
890 			sysfs_remove_link(&dev->kobj, "device");
891 		}
892 
893 		down(&dev->class->sem);
894 		/* notify any interfaces that the device is now gone */
895 		list_for_each_entry(class_intf, &dev->class->interfaces, node)
896 			if (class_intf->remove_dev)
897 				class_intf->remove_dev(dev, class_intf);
898 		/* remove the device from the class list */
899 		list_del_init(&dev->node);
900 		up(&dev->class->sem);
901 
902 		/* If we live in a parent class-directory, unreference it */
903 		if (dev->kobj.parent->kset == &dev->class->class_dirs) {
904 			struct device *d;
905 			int other = 0;
906 
907 			/*
908 			 * if we are the last child of our class, delete
909 			 * our class-directory at this parent
910 			 */
911 			down(&dev->class->sem);
912 			list_for_each_entry(d, &dev->class->devices, node) {
913 				if (d == dev)
914 					continue;
915 				if (d->kobj.parent == dev->kobj.parent) {
916 					other = 1;
917 					break;
918 				}
919 			}
920 			if (!other)
921 				kobject_del(dev->kobj.parent);
922 
923 			kobject_put(dev->kobj.parent);
924 			up(&dev->class->sem);
925 		}
926 	}
927 	device_remove_file(dev, &dev->uevent_attr);
928 	device_remove_attrs(dev);
929 	bus_remove_device(dev);
930 
931 	/*
932 	 * Some platform devices are driven without driver attached
933 	 * and managed resources may have been acquired.  Make sure
934 	 * all resources are released.
935 	 */
936 	devres_release_all(dev);
937 
938 	/* Notify the platform of the removal, in case they
939 	 * need to do anything...
940 	 */
941 	if (platform_notify_remove)
942 		platform_notify_remove(dev);
943 	if (dev->bus)
944 		blocking_notifier_call_chain(&dev->bus->bus_notifier,
945 					     BUS_NOTIFY_DEL_DEVICE, dev);
946 	device_pm_remove(dev);
947 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
948 	kobject_del(&dev->kobj);
949 	if (parent)
950 		put_device(parent);
951 }
952 
953 /**
954  *	device_unregister - unregister device from system.
955  *	@dev:	device going away.
956  *
957  *	We do this in two parts, like we do device_register(). First,
958  *	we remove it from all the subsystems with device_del(), then
959  *	we decrement the reference count via put_device(). If that
960  *	is the final reference count, the device will be cleaned up
961  *	via device_release() above. Otherwise, the structure will
962  *	stick around until the final reference to the device is dropped.
963  */
964 void device_unregister(struct device * dev)
965 {
966 	pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
967 	device_del(dev);
968 	put_device(dev);
969 }
970 
971 
972 static struct device * next_device(struct klist_iter * i)
973 {
974 	struct klist_node * n = klist_next(i);
975 	return n ? container_of(n, struct device, knode_parent) : NULL;
976 }
977 
978 /**
979  *	device_for_each_child - device child iterator.
980  *	@parent: parent struct device.
981  *	@data:	data for the callback.
982  *	@fn:	function to be called for each device.
983  *
984  *	Iterate over @parent's child devices, and call @fn for each,
985  *	passing it @data.
986  *
987  *	We check the return of @fn each time. If it returns anything
988  *	other than 0, we break out and return that value.
989  */
990 int device_for_each_child(struct device * parent, void * data,
991 		     int (*fn)(struct device *, void *))
992 {
993 	struct klist_iter i;
994 	struct device * child;
995 	int error = 0;
996 
997 	klist_iter_init(&parent->klist_children, &i);
998 	while ((child = next_device(&i)) && !error)
999 		error = fn(child, data);
1000 	klist_iter_exit(&i);
1001 	return error;
1002 }
1003 
1004 /**
1005  * device_find_child - device iterator for locating a particular device.
1006  * @parent: parent struct device
1007  * @data: Data to pass to match function
1008  * @match: Callback function to check device
1009  *
1010  * This is similar to the device_for_each_child() function above, but it
1011  * returns a reference to a device that is 'found' for later use, as
1012  * determined by the @match callback.
1013  *
1014  * The callback should return 0 if the device doesn't match and non-zero
1015  * if it does.  If the callback returns non-zero and a reference to the
1016  * current device can be obtained, this function will return to the caller
1017  * and not iterate over any more devices.
1018  */
1019 struct device * device_find_child(struct device *parent, void *data,
1020 				  int (*match)(struct device *, void *))
1021 {
1022 	struct klist_iter i;
1023 	struct device *child;
1024 
1025 	if (!parent)
1026 		return NULL;
1027 
1028 	klist_iter_init(&parent->klist_children, &i);
1029 	while ((child = next_device(&i)))
1030 		if (match(child, data) && get_device(child))
1031 			break;
1032 	klist_iter_exit(&i);
1033 	return child;
1034 }
1035 
1036 int __init devices_init(void)
1037 {
1038 	return subsystem_register(&devices_subsys);
1039 }
1040 
1041 EXPORT_SYMBOL_GPL(device_for_each_child);
1042 EXPORT_SYMBOL_GPL(device_find_child);
1043 
1044 EXPORT_SYMBOL_GPL(device_initialize);
1045 EXPORT_SYMBOL_GPL(device_add);
1046 EXPORT_SYMBOL_GPL(device_register);
1047 
1048 EXPORT_SYMBOL_GPL(device_del);
1049 EXPORT_SYMBOL_GPL(device_unregister);
1050 EXPORT_SYMBOL_GPL(get_device);
1051 EXPORT_SYMBOL_GPL(put_device);
1052 
1053 EXPORT_SYMBOL_GPL(device_create_file);
1054 EXPORT_SYMBOL_GPL(device_remove_file);
1055 
1056 
1057 static void device_create_release(struct device *dev)
1058 {
1059 	pr_debug("%s called for %s\n", __FUNCTION__, dev->bus_id);
1060 	kfree(dev);
1061 }
1062 
1063 /**
1064  * device_create - creates a device and registers it with sysfs
1065  * @class: pointer to the struct class that this device should be registered to
1066  * @parent: pointer to the parent struct device of this new device, if any
1067  * @devt: the dev_t for the char device to be added
1068  * @fmt: string for the device's name
1069  *
1070  * This function can be used by char device classes.  A struct device
1071  * will be created in sysfs, registered to the specified class.
1072  *
1073  * A "dev" file will be created, showing the dev_t for the device, if
1074  * the dev_t is not 0,0.
1075  * If a pointer to a parent struct device is passed in, the newly created
1076  * struct device will be a child of that device in sysfs.
1077  * The pointer to the struct device will be returned from the call.
1078  * Any further sysfs files that might be required can be created using this
1079  * pointer.
1080  *
1081  * Note: the struct class passed to this function must have previously
1082  * been created with a call to class_create().
1083  */
1084 struct device *device_create(struct class *class, struct device *parent,
1085 			     dev_t devt, const char *fmt, ...)
1086 {
1087 	va_list args;
1088 	struct device *dev = NULL;
1089 	int retval = -ENODEV;
1090 
1091 	if (class == NULL || IS_ERR(class))
1092 		goto error;
1093 
1094 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1095 	if (!dev) {
1096 		retval = -ENOMEM;
1097 		goto error;
1098 	}
1099 
1100 	dev->devt = devt;
1101 	dev->class = class;
1102 	dev->parent = parent;
1103 	dev->release = device_create_release;
1104 
1105 	va_start(args, fmt);
1106 	vsnprintf(dev->bus_id, BUS_ID_SIZE, fmt, args);
1107 	va_end(args);
1108 	retval = device_register(dev);
1109 	if (retval)
1110 		goto error;
1111 
1112 	return dev;
1113 
1114 error:
1115 	kfree(dev);
1116 	return ERR_PTR(retval);
1117 }
1118 EXPORT_SYMBOL_GPL(device_create);
1119 
1120 /**
1121  * device_destroy - removes a device that was created with device_create()
1122  * @class: pointer to the struct class that this device was registered with
1123  * @devt: the dev_t of the device that was previously registered
1124  *
1125  * This call unregisters and cleans up a device that was created with a
1126  * call to device_create().
1127  */
1128 void device_destroy(struct class *class, dev_t devt)
1129 {
1130 	struct device *dev = NULL;
1131 	struct device *dev_tmp;
1132 
1133 	down(&class->sem);
1134 	list_for_each_entry(dev_tmp, &class->devices, node) {
1135 		if (dev_tmp->devt == devt) {
1136 			dev = dev_tmp;
1137 			break;
1138 		}
1139 	}
1140 	up(&class->sem);
1141 
1142 	if (dev)
1143 		device_unregister(dev);
1144 }
1145 EXPORT_SYMBOL_GPL(device_destroy);
1146 
1147 /**
1148  * device_rename - renames a device
1149  * @dev: the pointer to the struct device to be renamed
1150  * @new_name: the new name of the device
1151  */
1152 int device_rename(struct device *dev, char *new_name)
1153 {
1154 	char *old_class_name = NULL;
1155 	char *new_class_name = NULL;
1156 	char *old_symlink_name = NULL;
1157 	int error;
1158 
1159 	dev = get_device(dev);
1160 	if (!dev)
1161 		return -EINVAL;
1162 
1163 	pr_debug("DEVICE: renaming '%s' to '%s'\n", dev->bus_id, new_name);
1164 
1165 #ifdef CONFIG_SYSFS_DEPRECATED
1166 	if ((dev->class) && (dev->parent))
1167 		old_class_name = make_class_name(dev->class->name, &dev->kobj);
1168 #endif
1169 
1170 	if (dev->class) {
1171 		old_symlink_name = kmalloc(BUS_ID_SIZE, GFP_KERNEL);
1172 		if (!old_symlink_name) {
1173 			error = -ENOMEM;
1174 			goto out_free_old_class;
1175 		}
1176 		strlcpy(old_symlink_name, dev->bus_id, BUS_ID_SIZE);
1177 	}
1178 
1179 	strlcpy(dev->bus_id, new_name, BUS_ID_SIZE);
1180 
1181 	error = kobject_rename(&dev->kobj, new_name);
1182 
1183 #ifdef CONFIG_SYSFS_DEPRECATED
1184 	if (old_class_name) {
1185 		new_class_name = make_class_name(dev->class->name, &dev->kobj);
1186 		if (new_class_name) {
1187 			sysfs_create_link(&dev->parent->kobj, &dev->kobj,
1188 					  new_class_name);
1189 			sysfs_remove_link(&dev->parent->kobj, old_class_name);
1190 		}
1191 	}
1192 #endif
1193 
1194 	if (dev->class) {
1195 		sysfs_remove_link(&dev->class->subsys.kobj,
1196 				  old_symlink_name);
1197 		sysfs_create_link(&dev->class->subsys.kobj, &dev->kobj,
1198 				  dev->bus_id);
1199 	}
1200 	put_device(dev);
1201 
1202 	kfree(new_class_name);
1203 	kfree(old_symlink_name);
1204  out_free_old_class:
1205 	kfree(old_class_name);
1206 
1207 	return error;
1208 }
1209 EXPORT_SYMBOL_GPL(device_rename);
1210 
1211 static int device_move_class_links(struct device *dev,
1212 				   struct device *old_parent,
1213 				   struct device *new_parent)
1214 {
1215 	int error = 0;
1216 #ifdef CONFIG_SYSFS_DEPRECATED
1217 	char *class_name;
1218 
1219 	class_name = make_class_name(dev->class->name, &dev->kobj);
1220 	if (!class_name) {
1221 		error = -ENOMEM;
1222 		goto out;
1223 	}
1224 	if (old_parent) {
1225 		sysfs_remove_link(&dev->kobj, "device");
1226 		sysfs_remove_link(&old_parent->kobj, class_name);
1227 	}
1228 	if (new_parent) {
1229 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
1230 					  "device");
1231 		if (error)
1232 			goto out;
1233 		error = sysfs_create_link(&new_parent->kobj, &dev->kobj,
1234 					  class_name);
1235 		if (error)
1236 			sysfs_remove_link(&dev->kobj, "device");
1237 	}
1238 	else
1239 		error = 0;
1240 out:
1241 	kfree(class_name);
1242 	return error;
1243 #else
1244 	if (old_parent)
1245 		sysfs_remove_link(&dev->kobj, "device");
1246 	if (new_parent)
1247 		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
1248 					  "device");
1249 	return error;
1250 #endif
1251 }
1252 
1253 /**
1254  * device_move - moves a device to a new parent
1255  * @dev: the pointer to the struct device to be moved
1256  * @new_parent: the new parent of the device (can by NULL)
1257  */
1258 int device_move(struct device *dev, struct device *new_parent)
1259 {
1260 	int error;
1261 	struct device *old_parent;
1262 	struct kobject *new_parent_kobj;
1263 
1264 	dev = get_device(dev);
1265 	if (!dev)
1266 		return -EINVAL;
1267 
1268 	new_parent = get_device(new_parent);
1269 	new_parent_kobj = get_device_parent (dev, new_parent);
1270 	if (IS_ERR(new_parent_kobj)) {
1271 		error = PTR_ERR(new_parent_kobj);
1272 		put_device(new_parent);
1273 		goto out;
1274 	}
1275 	pr_debug("DEVICE: moving '%s' to '%s'\n", dev->bus_id,
1276 		 new_parent ? new_parent->bus_id : "<NULL>");
1277 	error = kobject_move(&dev->kobj, new_parent_kobj);
1278 	if (error) {
1279 		put_device(new_parent);
1280 		goto out;
1281 	}
1282 	old_parent = dev->parent;
1283 	dev->parent = new_parent;
1284 	if (old_parent)
1285 		klist_remove(&dev->knode_parent);
1286 	if (new_parent)
1287 		klist_add_tail(&dev->knode_parent, &new_parent->klist_children);
1288 	if (!dev->class)
1289 		goto out_put;
1290 	error = device_move_class_links(dev, old_parent, new_parent);
1291 	if (error) {
1292 		/* We ignore errors on cleanup since we're hosed anyway... */
1293 		device_move_class_links(dev, new_parent, old_parent);
1294 		if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
1295 			if (new_parent)
1296 				klist_remove(&dev->knode_parent);
1297 			if (old_parent)
1298 				klist_add_tail(&dev->knode_parent,
1299 					       &old_parent->klist_children);
1300 		}
1301 		put_device(new_parent);
1302 		goto out;
1303 	}
1304 out_put:
1305 	put_device(old_parent);
1306 out:
1307 	put_device(dev);
1308 	return error;
1309 }
1310 
1311 EXPORT_SYMBOL_GPL(device_move);
1312