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Root/drivers/base/bus.c

1	/*
2	* bus.c - bus driver management
3	*
4	* Copyright (c) 2002-3 Patrick Mochel
5	* Copyright (c) 2002-3 Open Source Development Labs
6	* Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
7	* Copyright (c) 2007 Novell Inc.
8	*
9	* This file is released under the GPLv2
10	*
11	*/
12
13	#include <linux/device.h>
14	#include <linux/module.h>
15	#include <linux/errno.h>
16	#include <linux/slab.h>
17	#include <linux/init.h>
18	#include <linux/string.h>
19	#include <linux/mutex.h>
20	#include "base.h"
21	#include "power/power.h"
22
23	/* /sys/devices/system */
24	static struct kset *system_kset;
25
26	#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
27
28	/*
29	* sysfs bindings for drivers
30	*/
31
32	#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
33
34
35	static int __must_check bus_rescan_devices_helper(struct device *dev,
36	void *data);
37
38	static struct bus_type bus_get(struct bus_type bus)
39	{
40	if (bus) {
41	kset_get(&bus->p->subsys);
42	return bus;
43	}
44	return NULL;
45	}
46
47	static void bus_put(struct bus_type *bus)
48	{
49	if (bus)
50	kset_put(&bus->p->subsys);
51	}
52
53	static ssize_t drv_attr_show(struct kobject kobj, struct attribute attr,
54	char *buf)
55	{
56	struct driver_attribute *drv_attr = to_drv_attr(attr);
57	struct driver_private *drv_priv = to_driver(kobj);
58	ssize_t ret = -EIO;
59
60	if (drv_attr->show)
61	ret = drv_attr->show(drv_priv->driver, buf);
62	return ret;
63	}
64
65	static ssize_t drv_attr_store(struct kobject kobj, struct attribute attr,
66	const char *buf, size_t count)
67	{
68	struct driver_attribute *drv_attr = to_drv_attr(attr);
69	struct driver_private *drv_priv = to_driver(kobj);
70	ssize_t ret = -EIO;
71
72	if (drv_attr->store)
73	ret = drv_attr->store(drv_priv->driver, buf, count);
74	return ret;
75	}
76
77	static const struct sysfs_ops driver_sysfs_ops = {
78	.show = drv_attr_show,
79	.store = drv_attr_store,
80	};
81
82	static void driver_release(struct kobject *kobj)
83	{
84	struct driver_private *drv_priv = to_driver(kobj);
85
86	pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
87	kfree(drv_priv);
88	}
89
90	static struct kobj_type driver_ktype = {
91	.sysfs_ops = &driver_sysfs_ops,
92	.release = driver_release,
93	};
94
95	/*
96	* sysfs bindings for buses
97	*/
98	static ssize_t bus_attr_show(struct kobject kobj, struct attribute attr,
99	char *buf)
100	{
101	struct bus_attribute *bus_attr = to_bus_attr(attr);
102	struct subsys_private *subsys_priv = to_subsys_private(kobj);
103	ssize_t ret = 0;
104
105	if (bus_attr->show)
106	ret = bus_attr->show(subsys_priv->bus, buf);
107	return ret;
108	}
109
110	static ssize_t bus_attr_store(struct kobject kobj, struct attribute attr,
111	const char *buf, size_t count)
112	{
113	struct bus_attribute *bus_attr = to_bus_attr(attr);
114	struct subsys_private *subsys_priv = to_subsys_private(kobj);
115	ssize_t ret = 0;
116
117	if (bus_attr->store)
118	ret = bus_attr->store(subsys_priv->bus, buf, count);
119	return ret;
120	}
121
122	static const struct sysfs_ops bus_sysfs_ops = {
123	.show = bus_attr_show,
124	.store = bus_attr_store,
125	};
126
127	int bus_create_file(struct bus_type bus, struct bus_attribute attr)
128	{
129	int error;
130	if (bus_get(bus)) {
131	error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
132	bus_put(bus);
133	} else
134	error = -EINVAL;
135	return error;
136	}
137	EXPORT_SYMBOL_GPL(bus_create_file);
138
139	void bus_remove_file(struct bus_type bus, struct bus_attribute attr)
140	{
141	if (bus_get(bus)) {
142	sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
143	bus_put(bus);
144	}
145	}
146	EXPORT_SYMBOL_GPL(bus_remove_file);
147
148	static struct kobj_type bus_ktype = {
149	.sysfs_ops = &bus_sysfs_ops,
150	};
151
152	static int bus_uevent_filter(struct kset kset, struct kobject kobj)
153	{
154	struct kobj_type *ktype = get_ktype(kobj);
155
156	if (ktype == &bus_ktype)
157	return 1;
158	return 0;
159	}
160
161	static const struct kset_uevent_ops bus_uevent_ops = {
162	.filter = bus_uevent_filter,
163	};
164
165	static struct kset *bus_kset;
166
167
168	#ifdef CONFIG_HOTPLUG
169	/* Manually detach a device from its associated driver. */
170	static ssize_t driver_unbind(struct device_driver *drv,
171	const char *buf, size_t count)
172	{
173	struct bus_type *bus = bus_get(drv->bus);
174	struct device *dev;
175	int err = -ENODEV;
176
177	dev = bus_find_device_by_name(bus, NULL, buf);
178	if (dev && dev->driver == drv) {
179	if (dev->parent) /* Needed for USB */
180	device_lock(dev->parent);
181	device_release_driver(dev);
182	if (dev->parent)
183	device_unlock(dev->parent);
184	err = count;
185	}
186	put_device(dev);
187	bus_put(bus);
188	return err;
189	}
190	static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
191
192	/*
193	* Manually attach a device to a driver.
194	* Note: the driver must want to bind to the device,
195	* it is not possible to override the driver's id table.
196	*/
197	static ssize_t driver_bind(struct device_driver *drv,
198	const char *buf, size_t count)
199	{
200	struct bus_type *bus = bus_get(drv->bus);
201	struct device *dev;
202	int err = -ENODEV;
203
204	dev = bus_find_device_by_name(bus, NULL, buf);
205	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
206	if (dev->parent) /* Needed for USB */
207	device_lock(dev->parent);
208	device_lock(dev);
209	err = driver_probe_device(drv, dev);
210	device_unlock(dev);
211	if (dev->parent)
212	device_unlock(dev->parent);
213
214	if (err > 0) {
215	/* success */
216	err = count;
217	} else if (err == 0) {
218	/* driver didn't accept device */
219	err = -ENODEV;
220	}
221	}
222	put_device(dev);
223	bus_put(bus);
224	return err;
225	}
226	static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
227
228	static ssize_t show_drivers_autoprobe(struct bus_type bus, char buf)
229	{
230	return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
231	}
232
233	static ssize_t store_drivers_autoprobe(struct bus_type *bus,
234	const char *buf, size_t count)
235	{
236	if (buf[0] == '0')
237	bus->p->drivers_autoprobe = 0;
238	else
239	bus->p->drivers_autoprobe = 1;
240	return count;
241	}
242
243	static ssize_t store_drivers_probe(struct bus_type *bus,
244	const char *buf, size_t count)
245	{
246	struct device *dev;
247
248	dev = bus_find_device_by_name(bus, NULL, buf);
249	if (!dev)
250	return -ENODEV;
251	if (bus_rescan_devices_helper(dev, NULL) != 0)
252	return -EINVAL;
253	return count;
254	}
255	#endif
256
257	static struct device next_device(struct klist_iter i)
258	{
259	struct klist_node *n = klist_next(i);
260	struct device *dev = NULL;
261	struct device_private *dev_prv;
262
263	if (n) {
264	dev_prv = to_device_private_bus(n);
265	dev = dev_prv->device;
266	}
267	return dev;
268	}
269
270	/**
271	* bus_for_each_dev - device iterator.
272	* @bus: bus type.
273	* @start: device to start iterating from.
274	* @data: data for the callback.
275	* @fn: function to be called for each device.
276	*
277	* Iterate over @bus's list of devices, and call @fn for each,
278	* passing it @data. If @start is not NULL, we use that device to
279	* begin iterating from.
280	*
281	* We check the return of @fn each time. If it returns anything
282	* other than 0, we break out and return that value.
283	*
284	* NOTE: The device that returns a non-zero value is not retained
285	* in any way, nor is its refcount incremented. If the caller needs
286	* to retain this data, it should do so, and increment the reference
287	* count in the supplied callback.
288	*/
289	int bus_for_each_dev(struct bus_type bus, struct device start,
290	void data, int (fn)(struct device , void ))
291	{
292	struct klist_iter i;
293	struct device *dev;
294	int error = 0;
295
296	if (!bus)
297	return -EINVAL;
298
299	klist_iter_init_node(&bus->p->klist_devices, &i,
300	(start ? &start->p->knode_bus : NULL));
301	while ((dev = next_device(&i)) && !error)
302	error = fn(dev, data);
303	klist_iter_exit(&i);
304	return error;
305	}
306	EXPORT_SYMBOL_GPL(bus_for_each_dev);
307
308	/**
309	* bus_find_device - device iterator for locating a particular device.
310	* @bus: bus type
311	* @start: Device to begin with
312	* @data: Data to pass to match function
313	* @match: Callback function to check device
314	*
315	* This is similar to the bus_for_each_dev() function above, but it
316	* returns a reference to a device that is 'found' for later use, as
317	* determined by the @match callback.
318	*
319	* The callback should return 0 if the device doesn't match and non-zero
320	* if it does. If the callback returns non-zero, this function will
321	* return to the caller and not iterate over any more devices.
322	*/
323	struct device bus_find_device(struct bus_type bus,
324	struct device start, void data,
325	int (match)(struct device dev, void *data))
326	{
327	struct klist_iter i;
328	struct device *dev;
329
330	if (!bus)
331	return NULL;
332
333	klist_iter_init_node(&bus->p->klist_devices, &i,
334	(start ? &start->p->knode_bus : NULL));
335	while ((dev = next_device(&i)))
336	if (match(dev, data) && get_device(dev))
337	break;
338	klist_iter_exit(&i);
339	return dev;
340	}
341	EXPORT_SYMBOL_GPL(bus_find_device);
342
343	static int match_name(struct device dev, void data)
344	{
345	const char *name = data;
346
347	return sysfs_streq(name, dev_name(dev));
348	}
349
350	/**
351	* bus_find_device_by_name - device iterator for locating a particular device of a specific name
352	* @bus: bus type
353	* @start: Device to begin with
354	* @name: name of the device to match
355	*
356	* This is similar to the bus_find_device() function above, but it handles
357	* searching by a name automatically, no need to write another strcmp matching
358	* function.
359	*/
360	struct device bus_find_device_by_name(struct bus_type bus,
361	struct device start, const char name)
362	{
363	return bus_find_device(bus, start, (void *)name, match_name);
364	}
365	EXPORT_SYMBOL_GPL(bus_find_device_by_name);
366
367	/**
368	* subsys_find_device_by_id - find a device with a specific enumeration number
369	* @subsys: subsystem
370	* @id: index 'id' in struct device
371	* @hint: device to check first
372	*
373	* Check the hint's next object and if it is a match return it directly,
374	* otherwise, fall back to a full list search. Either way a reference for
375	* the returned object is taken.
376	*/
377	struct device subsys_find_device_by_id(struct bus_type subsys, unsigned int id,
378	struct device *hint)
379	{
380	struct klist_iter i;
381	struct device *dev;
382
383	if (!subsys)
384	return NULL;
385
386	if (hint) {
387	klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
388	dev = next_device(&i);
389	if (dev && dev->id == id && get_device(dev)) {
390	klist_iter_exit(&i);
391	return dev;
392	}
393	klist_iter_exit(&i);
394	}
395
396	klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
397	while ((dev = next_device(&i))) {
398	if (dev->id == id && get_device(dev)) {
399	klist_iter_exit(&i);
400	return dev;
401	}
402	}
403	klist_iter_exit(&i);
404	return NULL;
405	}
406	EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
407
408	static struct device_driver next_driver(struct klist_iter i)
409	{
410	struct klist_node *n = klist_next(i);
411	struct driver_private *drv_priv;
412
413	if (n) {
414	drv_priv = container_of(n, struct driver_private, knode_bus);
415	return drv_priv->driver;
416	}
417	return NULL;
418	}
419
420	/**
421	* bus_for_each_drv - driver iterator
422	* @bus: bus we're dealing with.
423	* @start: driver to start iterating on.
424	* @data: data to pass to the callback.
425	* @fn: function to call for each driver.
426	*
427	* This is nearly identical to the device iterator above.
428	* We iterate over each driver that belongs to @bus, and call
429	* @fn for each. If @fn returns anything but 0, we break out
430	* and return it. If @start is not NULL, we use it as the head
431	* of the list.
432	*
433	* NOTE: we don't return the driver that returns a non-zero
434	* value, nor do we leave the reference count incremented for that
435	* driver. If the caller needs to know that info, it must set it
436	* in the callback. It must also be sure to increment the refcount
437	* so it doesn't disappear before returning to the caller.
438	*/
439	int bus_for_each_drv(struct bus_type bus, struct device_driver start,
440	void data, int (fn)(struct device_driver , void ))
441	{
442	struct klist_iter i;
443	struct device_driver *drv;
444	int error = 0;
445
446	if (!bus)
447	return -EINVAL;
448
449	klist_iter_init_node(&bus->p->klist_drivers, &i,
450	start ? &start->p->knode_bus : NULL);
451	while ((drv = next_driver(&i)) && !error)
452	error = fn(drv, data);
453	klist_iter_exit(&i);
454	return error;
455	}
456	EXPORT_SYMBOL_GPL(bus_for_each_drv);
457
458	static int device_add_attrs(struct bus_type bus, struct device dev)
459	{
460	int error = 0;
461	int i;
462
463	if (!bus->dev_attrs)
464	return 0;
465
466	for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
467	error = device_create_file(dev, &bus->dev_attrs[i]);
468	if (error) {
469	while (--i >= 0)
470	device_remove_file(dev, &bus->dev_attrs[i]);
471	break;
472	}
473	}
474	return error;
475	}
476
477	static void device_remove_attrs(struct bus_type bus, struct device dev)
478	{
479	int i;
480
481	if (bus->dev_attrs) {
482	for (i = 0; attr_name(bus->dev_attrs[i]); i++)
483	device_remove_file(dev, &bus->dev_attrs[i]);
484	}
485	}
486
487	/**
488	* bus_add_device - add device to bus
489	* @dev: device being added
490	*
491	* - Add device's bus attributes.
492	* - Create links to device's bus.
493	* - Add the device to its bus's list of devices.
494	*/
495	int bus_add_device(struct device *dev)
496	{
497	struct bus_type *bus = bus_get(dev->bus);
498	int error = 0;
499
500	if (bus) {
501	pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
502	error = device_add_attrs(bus, dev);
503	if (error)
504	goto out_put;
505	error = sysfs_create_link(&bus->p->devices_kset->kobj,
506	&dev->kobj, dev_name(dev));
507	if (error)
508	goto out_id;
509	error = sysfs_create_link(&dev->kobj,
510	&dev->bus->p->subsys.kobj, "subsystem");
511	if (error)
512	goto out_subsys;
513	klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
514	}
515	return 0;
516
517	out_subsys:
518	sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
519	out_id:
520	device_remove_attrs(bus, dev);
521	out_put:
522	bus_put(dev->bus);
523	return error;
524	}
525
526	/**
527	* bus_probe_device - probe drivers for a new device
528	* @dev: device to probe
529	*
530	* - Automatically probe for a driver if the bus allows it.
531	*/
532	void bus_probe_device(struct device *dev)
533	{
534	struct bus_type *bus = dev->bus;
535	struct subsys_interface *sif;
536	int ret;
537
538	if (!bus)
539	return;
540
541	if (bus->p->drivers_autoprobe) {
542	ret = device_attach(dev);
543	WARN_ON(ret < 0);
544	}
545
546	mutex_lock(&bus->p->mutex);
547	list_for_each_entry(sif, &bus->p->interfaces, node)
548	if (sif->add_dev)
549	sif->add_dev(dev, sif);
550	mutex_unlock(&bus->p->mutex);
551	}
552
553	/**
554	* bus_remove_device - remove device from bus
555	* @dev: device to be removed
556	*
557	* - Remove device from all interfaces.
558	* - Remove symlink from bus' directory.
559	* - Delete device from bus's list.
560	* - Detach from its driver.
561	* - Drop reference taken in bus_add_device().
562	*/
563	void bus_remove_device(struct device *dev)
564	{
565	struct bus_type *bus = dev->bus;
566	struct subsys_interface *sif;
567
568	if (!bus)
569	return;
570
571	mutex_lock(&bus->p->mutex);
572	list_for_each_entry(sif, &bus->p->interfaces, node)
573	if (sif->remove_dev)
574	sif->remove_dev(dev, sif);
575	mutex_unlock(&bus->p->mutex);
576
577	sysfs_remove_link(&dev->kobj, "subsystem");
578	sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
579	dev_name(dev));
580	device_remove_attrs(dev->bus, dev);
581	if (klist_node_attached(&dev->p->knode_bus))
582	klist_del(&dev->p->knode_bus);
583
584	pr_debug("bus: '%s': remove device %s\n",
585	dev->bus->name, dev_name(dev));
586	device_release_driver(dev);
587	bus_put(dev->bus);
588	}
589
590	static int driver_add_attrs(struct bus_type bus, struct device_driver drv)
591	{
592	int error = 0;
593	int i;
594
595	if (bus->drv_attrs) {
596	for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
597	error = driver_create_file(drv, &bus->drv_attrs[i]);
598	if (error)
599	goto err;
600	}
601	}
602	done:
603	return error;
604	err:
605	while (--i >= 0)
606	driver_remove_file(drv, &bus->drv_attrs[i]);
607	goto done;
608	}
609
610	static void driver_remove_attrs(struct bus_type *bus,
611	struct device_driver *drv)
612	{
613	int i;
614
615	if (bus->drv_attrs) {
616	for (i = 0; attr_name(bus->drv_attrs[i]); i++)
617	driver_remove_file(drv, &bus->drv_attrs[i]);
618	}
619	}
620
621	#ifdef CONFIG_HOTPLUG
622	/*
623	* Thanks to drivers making their tables __devinit, we can't allow manual
624	* bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
625	*/
626	static int __must_check add_bind_files(struct device_driver *drv)
627	{
628	int ret;
629
630	ret = driver_create_file(drv, &driver_attr_unbind);
631	if (ret == 0) {
632	ret = driver_create_file(drv, &driver_attr_bind);
633	if (ret)
634	driver_remove_file(drv, &driver_attr_unbind);
635	}
636	return ret;
637	}
638
639	static void remove_bind_files(struct device_driver *drv)
640	{
641	driver_remove_file(drv, &driver_attr_bind);
642	driver_remove_file(drv, &driver_attr_unbind);
643	}
644
645	static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
646	static BUS_ATTR(drivers_autoprobe, S_IWUSR \| S_IRUGO,
647	show_drivers_autoprobe, store_drivers_autoprobe);
648
649	static int add_probe_files(struct bus_type *bus)
650	{
651	int retval;
652
653	retval = bus_create_file(bus, &bus_attr_drivers_probe);
654	if (retval)
655	goto out;
656
657	retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
658	if (retval)
659	bus_remove_file(bus, &bus_attr_drivers_probe);
660	out:
661	return retval;
662	}
663
664	static void remove_probe_files(struct bus_type *bus)
665	{
666	bus_remove_file(bus, &bus_attr_drivers_autoprobe);
667	bus_remove_file(bus, &bus_attr_drivers_probe);
668	}
669	#else
670	static inline int add_bind_files(struct device_driver *drv) { return 0; }
671	static inline void remove_bind_files(struct device_driver *drv) {}
672	static inline int add_probe_files(struct bus_type *bus) { return 0; }
673	static inline void remove_probe_files(struct bus_type *bus) {}
674	#endif
675
676	static ssize_t driver_uevent_store(struct device_driver *drv,
677	const char *buf, size_t count)
678	{
679	enum kobject_action action;
680
681	if (kobject_action_type(buf, count, &action) == 0)
682	kobject_uevent(&drv->p->kobj, action);
683	return count;
684	}
685	static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
686
687	/**
688	* bus_add_driver - Add a driver to the bus.
689	* @drv: driver.
690	*/
691	int bus_add_driver(struct device_driver *drv)
692	{
693	struct bus_type *bus;
694	struct driver_private *priv;
695	int error = 0;
696
697	bus = bus_get(drv->bus);
698	if (!bus)
699	return -EINVAL;
700
701	pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
702
703	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
704	if (!priv) {
705	error = -ENOMEM;
706	goto out_put_bus;
707	}
708	klist_init(&priv->klist_devices, NULL, NULL);
709	priv->driver = drv;
710	drv->p = priv;
711	priv->kobj.kset = bus->p->drivers_kset;
712	error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
713	"%s", drv->name);
714	if (error)
715	goto out_unregister;
716
717	if (drv->bus->p->drivers_autoprobe) {
718	error = driver_attach(drv);
719	if (error)
720	goto out_unregister;
721	}
722	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
723	module_add_driver(drv->owner, drv);
724
725	error = driver_create_file(drv, &driver_attr_uevent);
726	if (error) {
727	printk(KERN_ERR "%s: uevent attr (%s) failed\n",
728	__func__, drv->name);
729	}
730	error = driver_add_attrs(bus, drv);
731	if (error) {
732	/* How the hell do we get out of this pickle? Give up */
733	printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
734	__func__, drv->name);
735	}
736
737	if (!drv->suppress_bind_attrs) {
738	error = add_bind_files(drv);
739	if (error) {
740	/* Ditto */
741	printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
742	__func__, drv->name);
743	}
744	}
745
746	return 0;
747
748	out_unregister:
749	kobject_put(&priv->kobj);
750	kfree(drv->p);
751	drv->p = NULL;
752	out_put_bus:
753	bus_put(bus);
754	return error;
755	}
756
757	/**
758	* bus_remove_driver - delete driver from bus's knowledge.
759	* @drv: driver.
760	*
761	* Detach the driver from the devices it controls, and remove
762	* it from its bus's list of drivers. Finally, we drop the reference
763	* to the bus we took in bus_add_driver().
764	*/
765	void bus_remove_driver(struct device_driver *drv)
766	{
767	if (!drv->bus)
768	return;
769
770	if (!drv->suppress_bind_attrs)
771	remove_bind_files(drv);
772	driver_remove_attrs(drv->bus, drv);
773	driver_remove_file(drv, &driver_attr_uevent);
774	klist_remove(&drv->p->knode_bus);
775	pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
776	driver_detach(drv);
777	module_remove_driver(drv);
778	kobject_put(&drv->p->kobj);
779	bus_put(drv->bus);
780	}
781
782	/* Helper for bus_rescan_devices's iter */
783	static int __must_check bus_rescan_devices_helper(struct device *dev,
784	void *data)
785	{
786	int ret = 0;
787
788	if (!dev->driver) {
789	if (dev->parent) /* Needed for USB */
790	device_lock(dev->parent);
791	ret = device_attach(dev);
792	if (dev->parent)
793	device_unlock(dev->parent);
794	}
795	return ret < 0 ? ret : 0;
796	}
797
798	/**
799	* bus_rescan_devices - rescan devices on the bus for possible drivers
800	* @bus: the bus to scan.
801	*
802	* This function will look for devices on the bus with no driver
803	* attached and rescan it against existing drivers to see if it matches
804	* any by calling device_attach() for the unbound devices.
805	*/
806	int bus_rescan_devices(struct bus_type *bus)
807	{
808	return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
809	}
810	EXPORT_SYMBOL_GPL(bus_rescan_devices);
811
812	/**
813	* device_reprobe - remove driver for a device and probe for a new driver
814	* @dev: the device to reprobe
815	*
816	* This function detaches the attached driver (if any) for the given
817	* device and restarts the driver probing process. It is intended
818	* to use if probing criteria changed during a devices lifetime and
819	* driver attachment should change accordingly.
820	*/
821	int device_reprobe(struct device *dev)
822	{
823	if (dev->driver) {
824	if (dev->parent) /* Needed for USB */
825	device_lock(dev->parent);
826	device_release_driver(dev);
827	if (dev->parent)
828	device_unlock(dev->parent);
829	}
830	return bus_rescan_devices_helper(dev, NULL);
831	}
832	EXPORT_SYMBOL_GPL(device_reprobe);
833
834	/**
835	* find_bus - locate bus by name.
836	* @name: name of bus.
837	*
838	* Call kset_find_obj() to iterate over list of buses to
839	* find a bus by name. Return bus if found.
840	*
841	* Note that kset_find_obj increments bus' reference count.
842	*/
843	#if 0
844	struct bus_type find_bus(char name)
845	{
846	struct kobject *k = kset_find_obj(bus_kset, name);
847	return k ? to_bus(k) : NULL;
848	}
849	#endif /* 0 */
850
851
852	/**
853	* bus_add_attrs - Add default attributes for this bus.
854	* @bus: Bus that has just been registered.
855	*/
856
857	static int bus_add_attrs(struct bus_type *bus)
858	{
859	int error = 0;
860	int i;
861
862	if (bus->bus_attrs) {
863	for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
864	error = bus_create_file(bus, &bus->bus_attrs[i]);
865	if (error)
866	goto err;
867	}
868	}
869	done:
870	return error;
871	err:
872	while (--i >= 0)
873	bus_remove_file(bus, &bus->bus_attrs[i]);
874	goto done;
875	}
876
877	static void bus_remove_attrs(struct bus_type *bus)
878	{
879	int i;
880
881	if (bus->bus_attrs) {
882	for (i = 0; attr_name(bus->bus_attrs[i]); i++)
883	bus_remove_file(bus, &bus->bus_attrs[i]);
884	}
885	}
886
887	static void klist_devices_get(struct klist_node *n)
888	{
889	struct device_private *dev_prv = to_device_private_bus(n);
890	struct device *dev = dev_prv->device;
891
892	get_device(dev);
893	}
894
895	static void klist_devices_put(struct klist_node *n)
896	{
897	struct device_private *dev_prv = to_device_private_bus(n);
898	struct device *dev = dev_prv->device;
899
900	put_device(dev);
901	}
902
903	static ssize_t bus_uevent_store(struct bus_type *bus,
904	const char *buf, size_t count)
905	{
906	enum kobject_action action;
907
908	if (kobject_action_type(buf, count, &action) == 0)
909	kobject_uevent(&bus->p->subsys.kobj, action);
910	return count;
911	}
912	static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
913
914	/**
915	* __bus_register - register a driver-core subsystem
916	* @bus: bus to register
917	* @key: lockdep class key
918	*
919	* Once we have that, we register the bus with the kobject
920	* infrastructure, then register the children subsystems it has:
921	* the devices and drivers that belong to the subsystem.
922	*/
923	int __bus_register(struct bus_type bus, struct lock_class_key key)
924	{
925	int retval;
926	struct subsys_private *priv;
927
928	priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
929	if (!priv)
930	return -ENOMEM;
931
932	priv->bus = bus;
933	bus->p = priv;
934
935	BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
936
937	retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
938	if (retval)
939	goto out;
940
941	priv->subsys.kobj.kset = bus_kset;
942	priv->subsys.kobj.ktype = &bus_ktype;
943	priv->drivers_autoprobe = 1;
944
945	retval = kset_register(&priv->subsys);
946	if (retval)
947	goto out;
948
949	retval = bus_create_file(bus, &bus_attr_uevent);
950	if (retval)
951	goto bus_uevent_fail;
952
953	priv->devices_kset = kset_create_and_add("devices", NULL,
954	&priv->subsys.kobj);
955	if (!priv->devices_kset) {
956	retval = -ENOMEM;
957	goto bus_devices_fail;
958	}
959
960	priv->drivers_kset = kset_create_and_add("drivers", NULL,
961	&priv->subsys.kobj);
962	if (!priv->drivers_kset) {
963	retval = -ENOMEM;
964	goto bus_drivers_fail;
965	}
966
967	INIT_LIST_HEAD(&priv->interfaces);
968	__mutex_init(&priv->mutex, "subsys mutex", key);
969	klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
970	klist_init(&priv->klist_drivers, NULL, NULL);
971
972	retval = add_probe_files(bus);
973	if (retval)
974	goto bus_probe_files_fail;
975
976	retval = bus_add_attrs(bus);
977	if (retval)
978	goto bus_attrs_fail;
979
980	pr_debug("bus: '%s': registered\n", bus->name);
981	return 0;
982
983	bus_attrs_fail:
984	remove_probe_files(bus);
985	bus_probe_files_fail:
986	kset_unregister(bus->p->drivers_kset);
987	bus_drivers_fail:
988	kset_unregister(bus->p->devices_kset);
989	bus_devices_fail:
990	bus_remove_file(bus, &bus_attr_uevent);
991	bus_uevent_fail:
992	kset_unregister(&bus->p->subsys);
993	out:
994	kfree(bus->p);
995	bus->p = NULL;
996	return retval;
997	}
998	EXPORT_SYMBOL_GPL(__bus_register);
999
1000	/**
1001	* bus_unregister - remove a bus from the system
1002	* @bus: bus.
1003	*
1004	* Unregister the child subsystems and the bus itself.
1005	* Finally, we call bus_put() to release the refcount
1006	*/
1007	void bus_unregister(struct bus_type *bus)
1008	{
1009	pr_debug("bus: '%s': unregistering\n", bus->name);
1010	if (bus->dev_root)
1011	device_unregister(bus->dev_root);
1012	bus_remove_attrs(bus);
1013	remove_probe_files(bus);
1014	kset_unregister(bus->p->drivers_kset);
1015	kset_unregister(bus->p->devices_kset);
1016	bus_remove_file(bus, &bus_attr_uevent);
1017	kset_unregister(&bus->p->subsys);
1018	kfree(bus->p);
1019	bus->p = NULL;
1020	}
1021	EXPORT_SYMBOL_GPL(bus_unregister);
1022
1023	int bus_register_notifier(struct bus_type bus, struct notifier_block nb)
1024	{
1025	return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
1026	}
1027	EXPORT_SYMBOL_GPL(bus_register_notifier);
1028
1029	int bus_unregister_notifier(struct bus_type bus, struct notifier_block nb)
1030	{
1031	return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
1032	}
1033	EXPORT_SYMBOL_GPL(bus_unregister_notifier);
1034
1035	struct kset bus_get_kset(struct bus_type bus)
1036	{
1037	return &bus->p->subsys;
1038	}
1039	EXPORT_SYMBOL_GPL(bus_get_kset);
1040
1041	struct klist bus_get_device_klist(struct bus_type bus)
1042	{
1043	return &bus->p->klist_devices;
1044	}
1045	EXPORT_SYMBOL_GPL(bus_get_device_klist);
1046
1047	/*
1048	* Yes, this forcibly breaks the klist abstraction temporarily. It
1049	* just wants to sort the klist, not change reference counts and
1050	* take/drop locks rapidly in the process. It does all this while
1051	* holding the lock for the list, so objects can't otherwise be
1052	* added/removed while we're swizzling.
1053	*/
1054	static void device_insertion_sort_klist(struct device a, struct list_head list,
1055	int (compare)(const struct device a,
1056	const struct device *b))
1057	{
1058	struct list_head *pos;
1059	struct klist_node *n;
1060	struct device_private *dev_prv;
1061	struct device *b;
1062
1063	list_for_each(pos, list) {
1064	n = container_of(pos, struct klist_node, n_node);
1065	dev_prv = to_device_private_bus(n);
1066	b = dev_prv->device;
1067	if (compare(a, b) <= 0) {
1068	list_move_tail(&a->p->knode_bus.n_node,
1069	&b->p->knode_bus.n_node);
1070	return;
1071	}
1072	}
1073	list_move_tail(&a->p->knode_bus.n_node, list);
1074	}
1075
1076	void bus_sort_breadthfirst(struct bus_type *bus,
1077	int (compare)(const struct device a,
1078	const struct device *b))
1079	{
1080	LIST_HEAD(sorted_devices);
1081	struct list_head pos, tmp;
1082	struct klist_node *n;
1083	struct device_private *dev_prv;
1084	struct device *dev;
1085	struct klist *device_klist;
1086
1087	device_klist = bus_get_device_klist(bus);
1088
1089	spin_lock(&device_klist->k_lock);
1090	list_for_each_safe(pos, tmp, &device_klist->k_list) {
1091	n = container_of(pos, struct klist_node, n_node);
1092	dev_prv = to_device_private_bus(n);
1093	dev = dev_prv->device;
1094	device_insertion_sort_klist(dev, &sorted_devices, compare);
1095	}
1096	list_splice(&sorted_devices, &device_klist->k_list);
1097	spin_unlock(&device_klist->k_lock);
1098	}
1099	EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1100
1101	/**
1102	* subsys_dev_iter_init - initialize subsys device iterator
1103	* @iter: subsys iterator to initialize
1104	* @subsys: the subsys we wanna iterate over
1105	* @start: the device to start iterating from, if any
1106	* @type: device_type of the devices to iterate over, NULL for all
1107	*
1108	* Initialize subsys iterator @iter such that it iterates over devices
1109	* of @subsys. If @start is set, the list iteration will start there,
1110	* otherwise if it is NULL, the iteration starts at the beginning of
1111	* the list.
1112	*/
1113	void subsys_dev_iter_init(struct subsys_dev_iter iter, struct bus_type subsys,
1114	struct device start, const struct device_type type)
1115	{
1116	struct klist_node *start_knode = NULL;
1117
1118	if (start)
1119	start_knode = &start->p->knode_bus;
1120	klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1121	iter->type = type;
1122	}
1123	EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1124
1125	/**
1126	* subsys_dev_iter_next - iterate to the next device
1127	* @iter: subsys iterator to proceed
1128	*
1129	* Proceed @iter to the next device and return it. Returns NULL if
1130	* iteration is complete.
1131	*
1132	* The returned device is referenced and won't be released till
1133	* iterator is proceed to the next device or exited. The caller is
1134	* free to do whatever it wants to do with the device including
1135	* calling back into subsys code.
1136	*/
1137	struct device subsys_dev_iter_next(struct subsys_dev_iter iter)
1138	{
1139	struct klist_node *knode;
1140	struct device *dev;
1141
1142	for (;;) {
1143	knode = klist_next(&iter->ki);
1144	if (!knode)
1145	return NULL;
1146	dev = container_of(knode, struct device_private, knode_bus)->device;
1147	if (!iter->type \|\| iter->type == dev->type)
1148	return dev;
1149	}
1150	}
1151	EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1152
1153	/**
1154	* subsys_dev_iter_exit - finish iteration
1155	* @iter: subsys iterator to finish
1156	*
1157	* Finish an iteration. Always call this function after iteration is
1158	* complete whether the iteration ran till the end or not.
1159	*/
1160	void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1161	{
1162	klist_iter_exit(&iter->ki);
1163	}
1164	EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1165
1166	int subsys_interface_register(struct subsys_interface *sif)
1167	{
1168	struct bus_type *subsys;
1169	struct subsys_dev_iter iter;
1170	struct device *dev;
1171
1172	if (!sif \|\| !sif->subsys)
1173	return -ENODEV;
1174
1175	subsys = bus_get(sif->subsys);
1176	if (!subsys)
1177	return -EINVAL;
1178
1179	mutex_lock(&subsys->p->mutex);
1180	list_add_tail(&sif->node, &subsys->p->interfaces);
1181	if (sif->add_dev) {
1182	subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1183	while ((dev = subsys_dev_iter_next(&iter)))
1184	sif->add_dev(dev, sif);
1185	subsys_dev_iter_exit(&iter);
1186	}
1187	mutex_unlock(&subsys->p->mutex);
1188
1189	return 0;
1190	}
1191	EXPORT_SYMBOL_GPL(subsys_interface_register);
1192
1193	void subsys_interface_unregister(struct subsys_interface *sif)
1194	{
1195	struct bus_type *subsys;
1196	struct subsys_dev_iter iter;
1197	struct device *dev;
1198
1199	if (!sif \|\| !sif->subsys)
1200	return;
1201
1202	subsys = sif->subsys;
1203
1204	mutex_lock(&subsys->p->mutex);
1205	list_del_init(&sif->node);
1206	if (sif->remove_dev) {
1207	subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1208	while ((dev = subsys_dev_iter_next(&iter)))
1209	sif->remove_dev(dev, sif);
1210	subsys_dev_iter_exit(&iter);
1211	}
1212	mutex_unlock(&subsys->p->mutex);
1213
1214	bus_put(subsys);
1215	}
1216	EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1217
1218	static void system_root_device_release(struct device *dev)
1219	{
1220	kfree(dev);
1221	}
1222	/**
1223	* subsys_system_register - register a subsystem at /sys/devices/system/
1224	* @subsys: system subsystem
1225	* @groups: default attributes for the root device
1226	*
1227	* All 'system' subsystems have a /sys/devices/system/<name> root device
1228	* with the name of the subsystem. The root device can carry subsystem-
1229	* wide attributes. All registered devices are below this single root
1230	* device and are named after the subsystem with a simple enumeration
1231	* number appended. The registered devices are not explicitely named;
1232	* only 'id' in the device needs to be set.
1233	*
1234	* Do not use this interface for anything new, it exists for compatibility
1235	* with bad ideas only. New subsystems should use plain subsystems; and
1236	* add the subsystem-wide attributes should be added to the subsystem
1237	* directory itself and not some create fake root-device placed in
1238	* /sys/devices/system/<name>.
1239	*/
1240	int subsys_system_register(struct bus_type *subsys,
1241	const struct attribute_group **groups)
1242	{
1243	struct device *dev;
1244	int err;
1245
1246	err = bus_register(subsys);
1247	if (err < 0)
1248	return err;
1249
1250	dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1251	if (!dev) {
1252	err = -ENOMEM;
1253	goto err_dev;
1254	}
1255
1256	err = dev_set_name(dev, "%s", subsys->name);
1257	if (err < 0)
1258	goto err_name;
1259
1260	dev->kobj.parent = &system_kset->kobj;
1261	dev->groups = groups;
1262	dev->release = system_root_device_release;
1263
1264	err = device_register(dev);
1265	if (err < 0)
1266	goto err_dev_reg;
1267
1268	subsys->dev_root = dev;
1269	return 0;
1270
1271	err_dev_reg:
1272	put_device(dev);
1273	dev = NULL;
1274	err_name:
1275	kfree(dev);
1276	err_dev:
1277	bus_unregister(subsys);
1278	return err;
1279	}
1280	EXPORT_SYMBOL_GPL(subsys_system_register);
1281
1282	int __init buses_init(void)
1283	{
1284	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1285	if (!bus_kset)
1286	return -ENOMEM;
1287
1288	system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1289	if (!system_kset)
1290	return -ENOMEM;
1291
1292	return 0;
1293	}
1294

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