1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * bus.c - bus driver management
4  *
5  * Copyright (c) 2002-3 Patrick Mochel
6  * Copyright (c) 2002-3 Open Source Development Labs
7  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
8  * Copyright (c) 2007 Novell Inc.
9  */
10 
11 #include <linux/async.h>
12 #include <linux/device.h>
13 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/string.h>
18 #include <linux/mutex.h>
19 #include <linux/sysfs.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 #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
35 	struct driver_attribute driver_attr_##_name =		\
36 		__ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
37 
38 static int __must_check bus_rescan_devices_helper(struct device *dev,
39 						void *data);
40 
bus_get(struct bus_type * bus)41 static struct bus_type *bus_get(struct bus_type *bus)
42 {
43 	if (bus) {
44 		kset_get(&bus->p->subsys);
45 		return bus;
46 	}
47 	return NULL;
48 }
49 
bus_put(struct bus_type * bus)50 static void bus_put(struct bus_type *bus)
51 {
52 	if (bus)
53 		kset_put(&bus->p->subsys);
54 }
55 
drv_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)56 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
57 			     char *buf)
58 {
59 	struct driver_attribute *drv_attr = to_drv_attr(attr);
60 	struct driver_private *drv_priv = to_driver(kobj);
61 	ssize_t ret = -EIO;
62 
63 	if (drv_attr->show)
64 		ret = drv_attr->show(drv_priv->driver, buf);
65 	return ret;
66 }
67 
drv_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t count)68 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
69 			      const char *buf, size_t count)
70 {
71 	struct driver_attribute *drv_attr = to_drv_attr(attr);
72 	struct driver_private *drv_priv = to_driver(kobj);
73 	ssize_t ret = -EIO;
74 
75 	if (drv_attr->store)
76 		ret = drv_attr->store(drv_priv->driver, buf, count);
77 	return ret;
78 }
79 
80 static const struct sysfs_ops driver_sysfs_ops = {
81 	.show	= drv_attr_show,
82 	.store	= drv_attr_store,
83 };
84 
driver_release(struct kobject * kobj)85 static void driver_release(struct kobject *kobj)
86 {
87 	struct driver_private *drv_priv = to_driver(kobj);
88 
89 	pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
90 	kfree(drv_priv);
91 }
92 
93 static struct kobj_type driver_ktype = {
94 	.sysfs_ops	= &driver_sysfs_ops,
95 	.release	= driver_release,
96 };
97 
98 /*
99  * sysfs bindings for buses
100  */
bus_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)101 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
102 			     char *buf)
103 {
104 	struct bus_attribute *bus_attr = to_bus_attr(attr);
105 	struct subsys_private *subsys_priv = to_subsys_private(kobj);
106 	ssize_t ret = 0;
107 
108 	if (bus_attr->show)
109 		ret = bus_attr->show(subsys_priv->bus, buf);
110 	return ret;
111 }
112 
bus_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t count)113 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
114 			      const char *buf, size_t count)
115 {
116 	struct bus_attribute *bus_attr = to_bus_attr(attr);
117 	struct subsys_private *subsys_priv = to_subsys_private(kobj);
118 	ssize_t ret = 0;
119 
120 	if (bus_attr->store)
121 		ret = bus_attr->store(subsys_priv->bus, buf, count);
122 	return ret;
123 }
124 
125 static const struct sysfs_ops bus_sysfs_ops = {
126 	.show	= bus_attr_show,
127 	.store	= bus_attr_store,
128 };
129 
bus_create_file(struct bus_type * bus,struct bus_attribute * attr)130 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
131 {
132 	int error;
133 	if (bus_get(bus)) {
134 		error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
135 		bus_put(bus);
136 	} else
137 		error = -EINVAL;
138 	return error;
139 }
140 EXPORT_SYMBOL_GPL(bus_create_file);
141 
bus_remove_file(struct bus_type * bus,struct bus_attribute * attr)142 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
143 {
144 	if (bus_get(bus)) {
145 		sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
146 		bus_put(bus);
147 	}
148 }
149 EXPORT_SYMBOL_GPL(bus_remove_file);
150 
bus_release(struct kobject * kobj)151 static void bus_release(struct kobject *kobj)
152 {
153 	struct subsys_private *priv = to_subsys_private(kobj);
154 	struct bus_type *bus = priv->bus;
155 
156 	kfree(priv);
157 	bus->p = NULL;
158 }
159 
160 static struct kobj_type bus_ktype = {
161 	.sysfs_ops	= &bus_sysfs_ops,
162 	.release	= bus_release,
163 };
164 
bus_uevent_filter(struct kset * kset,struct kobject * kobj)165 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
166 {
167 	struct kobj_type *ktype = get_ktype(kobj);
168 
169 	if (ktype == &bus_ktype)
170 		return 1;
171 	return 0;
172 }
173 
174 static const struct kset_uevent_ops bus_uevent_ops = {
175 	.filter = bus_uevent_filter,
176 };
177 
178 static struct kset *bus_kset;
179 
180 /* Manually detach a device from its associated driver. */
unbind_store(struct device_driver * drv,const char * buf,size_t count)181 static ssize_t unbind_store(struct device_driver *drv, const char *buf,
182 			    size_t count)
183 {
184 	struct bus_type *bus = bus_get(drv->bus);
185 	struct device *dev;
186 	int err = -ENODEV;
187 
188 	dev = bus_find_device_by_name(bus, NULL, buf);
189 	if (dev && dev->driver == drv) {
190 		if (dev->parent && dev->bus->need_parent_lock)
191 			device_lock(dev->parent);
192 		device_release_driver(dev);
193 		if (dev->parent && dev->bus->need_parent_lock)
194 			device_unlock(dev->parent);
195 		err = count;
196 	}
197 	put_device(dev);
198 	bus_put(bus);
199 	return err;
200 }
201 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
202 
203 /*
204  * Manually attach a device to a driver.
205  * Note: the driver must want to bind to the device,
206  * it is not possible to override the driver's id table.
207  */
bind_store(struct device_driver * drv,const char * buf,size_t count)208 static ssize_t bind_store(struct device_driver *drv, const char *buf,
209 			  size_t count)
210 {
211 	struct bus_type *bus = bus_get(drv->bus);
212 	struct device *dev;
213 	int err = -ENODEV;
214 
215 	dev = bus_find_device_by_name(bus, NULL, buf);
216 	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
217 		if (dev->parent && bus->need_parent_lock)
218 			device_lock(dev->parent);
219 		device_lock(dev);
220 		err = driver_probe_device(drv, dev);
221 		device_unlock(dev);
222 		if (dev->parent && bus->need_parent_lock)
223 			device_unlock(dev->parent);
224 
225 		if (err > 0) {
226 			/* success */
227 			err = count;
228 		} else if (err == 0) {
229 			/* driver didn't accept device */
230 			err = -ENODEV;
231 		}
232 	}
233 	put_device(dev);
234 	bus_put(bus);
235 	return err;
236 }
237 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
238 
show_drivers_autoprobe(struct bus_type * bus,char * buf)239 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
240 {
241 	return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
242 }
243 
store_drivers_autoprobe(struct bus_type * bus,const char * buf,size_t count)244 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
245 				       const char *buf, size_t count)
246 {
247 	if (buf[0] == '0')
248 		bus->p->drivers_autoprobe = 0;
249 	else
250 		bus->p->drivers_autoprobe = 1;
251 	return count;
252 }
253 
store_drivers_probe(struct bus_type * bus,const char * buf,size_t count)254 static ssize_t store_drivers_probe(struct bus_type *bus,
255 				   const char *buf, size_t count)
256 {
257 	struct device *dev;
258 	int err = -EINVAL;
259 
260 	dev = bus_find_device_by_name(bus, NULL, buf);
261 	if (!dev)
262 		return -ENODEV;
263 	if (bus_rescan_devices_helper(dev, NULL) == 0)
264 		err = count;
265 	put_device(dev);
266 	return err;
267 }
268 
next_device(struct klist_iter * i)269 static struct device *next_device(struct klist_iter *i)
270 {
271 	struct klist_node *n = klist_next(i);
272 	struct device *dev = NULL;
273 	struct device_private *dev_prv;
274 
275 	if (n) {
276 		dev_prv = to_device_private_bus(n);
277 		dev = dev_prv->device;
278 	}
279 	return dev;
280 }
281 
282 /**
283  * bus_for_each_dev - device iterator.
284  * @bus: bus type.
285  * @start: device to start iterating from.
286  * @data: data for the callback.
287  * @fn: function to be called for each device.
288  *
289  * Iterate over @bus's list of devices, and call @fn for each,
290  * passing it @data. If @start is not NULL, we use that device to
291  * begin iterating from.
292  *
293  * We check the return of @fn each time. If it returns anything
294  * other than 0, we break out and return that value.
295  *
296  * NOTE: The device that returns a non-zero value is not retained
297  * in any way, nor is its refcount incremented. If the caller needs
298  * to retain this data, it should do so, and increment the reference
299  * count in the supplied callback.
300  */
bus_for_each_dev(struct bus_type * bus,struct device * start,void * data,int (* fn)(struct device *,void *))301 int bus_for_each_dev(struct bus_type *bus, struct device *start,
302 		     void *data, int (*fn)(struct device *, void *))
303 {
304 	struct klist_iter i;
305 	struct device *dev;
306 	int error = 0;
307 
308 	if (!bus || !bus->p)
309 		return -EINVAL;
310 
311 	klist_iter_init_node(&bus->p->klist_devices, &i,
312 			     (start ? &start->p->knode_bus : NULL));
313 	while (!error && (dev = next_device(&i)))
314 		error = fn(dev, data);
315 	klist_iter_exit(&i);
316 	return error;
317 }
318 EXPORT_SYMBOL_GPL(bus_for_each_dev);
319 
320 /**
321  * bus_find_device - device iterator for locating a particular device.
322  * @bus: bus type
323  * @start: Device to begin with
324  * @data: Data to pass to match function
325  * @match: Callback function to check device
326  *
327  * This is similar to the bus_for_each_dev() function above, but it
328  * returns a reference to a device that is 'found' for later use, as
329  * determined by the @match callback.
330  *
331  * The callback should return 0 if the device doesn't match and non-zero
332  * if it does.  If the callback returns non-zero, this function will
333  * return to the caller and not iterate over any more devices.
334  */
bus_find_device(struct bus_type * bus,struct device * start,void * data,int (* match)(struct device * dev,void * data))335 struct device *bus_find_device(struct bus_type *bus,
336 			       struct device *start, void *data,
337 			       int (*match)(struct device *dev, void *data))
338 {
339 	struct klist_iter i;
340 	struct device *dev;
341 
342 	if (!bus || !bus->p)
343 		return NULL;
344 
345 	klist_iter_init_node(&bus->p->klist_devices, &i,
346 			     (start ? &start->p->knode_bus : NULL));
347 	while ((dev = next_device(&i)))
348 		if (match(dev, data) && get_device(dev))
349 			break;
350 	klist_iter_exit(&i);
351 	return dev;
352 }
353 EXPORT_SYMBOL_GPL(bus_find_device);
354 
match_name(struct device * dev,void * data)355 static int match_name(struct device *dev, void *data)
356 {
357 	const char *name = data;
358 
359 	return sysfs_streq(name, dev_name(dev));
360 }
361 
362 /**
363  * bus_find_device_by_name - device iterator for locating a particular device of a specific name
364  * @bus: bus type
365  * @start: Device to begin with
366  * @name: name of the device to match
367  *
368  * This is similar to the bus_find_device() function above, but it handles
369  * searching by a name automatically, no need to write another strcmp matching
370  * function.
371  */
bus_find_device_by_name(struct bus_type * bus,struct device * start,const char * name)372 struct device *bus_find_device_by_name(struct bus_type *bus,
373 				       struct device *start, const char *name)
374 {
375 	return bus_find_device(bus, start, (void *)name, match_name);
376 }
377 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
378 
379 /**
380  * subsys_find_device_by_id - find a device with a specific enumeration number
381  * @subsys: subsystem
382  * @id: index 'id' in struct device
383  * @hint: device to check first
384  *
385  * Check the hint's next object and if it is a match return it directly,
386  * otherwise, fall back to a full list search. Either way a reference for
387  * the returned object is taken.
388  */
subsys_find_device_by_id(struct bus_type * subsys,unsigned int id,struct device * hint)389 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
390 					struct device *hint)
391 {
392 	struct klist_iter i;
393 	struct device *dev;
394 
395 	if (!subsys)
396 		return NULL;
397 
398 	if (hint) {
399 		klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
400 		dev = next_device(&i);
401 		if (dev && dev->id == id && get_device(dev)) {
402 			klist_iter_exit(&i);
403 			return dev;
404 		}
405 		klist_iter_exit(&i);
406 	}
407 
408 	klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
409 	while ((dev = next_device(&i))) {
410 		if (dev->id == id && get_device(dev)) {
411 			klist_iter_exit(&i);
412 			return dev;
413 		}
414 	}
415 	klist_iter_exit(&i);
416 	return NULL;
417 }
418 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
419 
next_driver(struct klist_iter * i)420 static struct device_driver *next_driver(struct klist_iter *i)
421 {
422 	struct klist_node *n = klist_next(i);
423 	struct driver_private *drv_priv;
424 
425 	if (n) {
426 		drv_priv = container_of(n, struct driver_private, knode_bus);
427 		return drv_priv->driver;
428 	}
429 	return NULL;
430 }
431 
432 /**
433  * bus_for_each_drv - driver iterator
434  * @bus: bus we're dealing with.
435  * @start: driver to start iterating on.
436  * @data: data to pass to the callback.
437  * @fn: function to call for each driver.
438  *
439  * This is nearly identical to the device iterator above.
440  * We iterate over each driver that belongs to @bus, and call
441  * @fn for each. If @fn returns anything but 0, we break out
442  * and return it. If @start is not NULL, we use it as the head
443  * of the list.
444  *
445  * NOTE: we don't return the driver that returns a non-zero
446  * value, nor do we leave the reference count incremented for that
447  * driver. If the caller needs to know that info, it must set it
448  * in the callback. It must also be sure to increment the refcount
449  * so it doesn't disappear before returning to the caller.
450  */
bus_for_each_drv(struct bus_type * bus,struct device_driver * start,void * data,int (* fn)(struct device_driver *,void *))451 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
452 		     void *data, int (*fn)(struct device_driver *, void *))
453 {
454 	struct klist_iter i;
455 	struct device_driver *drv;
456 	int error = 0;
457 
458 	if (!bus)
459 		return -EINVAL;
460 
461 	klist_iter_init_node(&bus->p->klist_drivers, &i,
462 			     start ? &start->p->knode_bus : NULL);
463 	while ((drv = next_driver(&i)) && !error)
464 		error = fn(drv, data);
465 	klist_iter_exit(&i);
466 	return error;
467 }
468 EXPORT_SYMBOL_GPL(bus_for_each_drv);
469 
470 /**
471  * bus_add_device - add device to bus
472  * @dev: device being added
473  *
474  * - Add device's bus attributes.
475  * - Create links to device's bus.
476  * - Add the device to its bus's list of devices.
477  */
bus_add_device(struct device * dev)478 int bus_add_device(struct device *dev)
479 {
480 	struct bus_type *bus = bus_get(dev->bus);
481 	int error = 0;
482 
483 	if (bus) {
484 		pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
485 		error = device_add_groups(dev, bus->dev_groups);
486 		if (error)
487 			goto out_put;
488 		error = sysfs_create_link(&bus->p->devices_kset->kobj,
489 						&dev->kobj, dev_name(dev));
490 		if (error)
491 			goto out_groups;
492 		error = sysfs_create_link(&dev->kobj,
493 				&dev->bus->p->subsys.kobj, "subsystem");
494 		if (error)
495 			goto out_subsys;
496 		klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
497 	}
498 	return 0;
499 
500 out_subsys:
501 	sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
502 out_groups:
503 	device_remove_groups(dev, bus->dev_groups);
504 out_put:
505 	bus_put(dev->bus);
506 	return error;
507 }
508 
509 /**
510  * bus_probe_device - probe drivers for a new device
511  * @dev: device to probe
512  *
513  * - Automatically probe for a driver if the bus allows it.
514  */
bus_probe_device(struct device * dev)515 void bus_probe_device(struct device *dev)
516 {
517 	struct bus_type *bus = dev->bus;
518 	struct subsys_interface *sif;
519 
520 	if (!bus)
521 		return;
522 
523 	if (bus->p->drivers_autoprobe)
524 		device_initial_probe(dev);
525 
526 	mutex_lock(&bus->p->mutex);
527 	list_for_each_entry(sif, &bus->p->interfaces, node)
528 		if (sif->add_dev)
529 			sif->add_dev(dev, sif);
530 	mutex_unlock(&bus->p->mutex);
531 }
532 
533 /**
534  * bus_remove_device - remove device from bus
535  * @dev: device to be removed
536  *
537  * - Remove device from all interfaces.
538  * - Remove symlink from bus' directory.
539  * - Delete device from bus's list.
540  * - Detach from its driver.
541  * - Drop reference taken in bus_add_device().
542  */
bus_remove_device(struct device * dev)543 void bus_remove_device(struct device *dev)
544 {
545 	struct bus_type *bus = dev->bus;
546 	struct subsys_interface *sif;
547 
548 	if (!bus)
549 		return;
550 
551 	mutex_lock(&bus->p->mutex);
552 	list_for_each_entry(sif, &bus->p->interfaces, node)
553 		if (sif->remove_dev)
554 			sif->remove_dev(dev, sif);
555 	mutex_unlock(&bus->p->mutex);
556 
557 	sysfs_remove_link(&dev->kobj, "subsystem");
558 	sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
559 			  dev_name(dev));
560 	device_remove_groups(dev, dev->bus->dev_groups);
561 	if (klist_node_attached(&dev->p->knode_bus))
562 		klist_del(&dev->p->knode_bus);
563 
564 	pr_debug("bus: '%s': remove device %s\n",
565 		 dev->bus->name, dev_name(dev));
566 	device_release_driver(dev);
567 	bus_put(dev->bus);
568 }
569 
add_bind_files(struct device_driver * drv)570 static int __must_check add_bind_files(struct device_driver *drv)
571 {
572 	int ret;
573 
574 	ret = driver_create_file(drv, &driver_attr_unbind);
575 	if (ret == 0) {
576 		ret = driver_create_file(drv, &driver_attr_bind);
577 		if (ret)
578 			driver_remove_file(drv, &driver_attr_unbind);
579 	}
580 	return ret;
581 }
582 
remove_bind_files(struct device_driver * drv)583 static void remove_bind_files(struct device_driver *drv)
584 {
585 	driver_remove_file(drv, &driver_attr_bind);
586 	driver_remove_file(drv, &driver_attr_unbind);
587 }
588 
589 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
590 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
591 		show_drivers_autoprobe, store_drivers_autoprobe);
592 
add_probe_files(struct bus_type * bus)593 static int add_probe_files(struct bus_type *bus)
594 {
595 	int retval;
596 
597 	retval = bus_create_file(bus, &bus_attr_drivers_probe);
598 	if (retval)
599 		goto out;
600 
601 	retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
602 	if (retval)
603 		bus_remove_file(bus, &bus_attr_drivers_probe);
604 out:
605 	return retval;
606 }
607 
remove_probe_files(struct bus_type * bus)608 static void remove_probe_files(struct bus_type *bus)
609 {
610 	bus_remove_file(bus, &bus_attr_drivers_autoprobe);
611 	bus_remove_file(bus, &bus_attr_drivers_probe);
612 }
613 
uevent_store(struct device_driver * drv,const char * buf,size_t count)614 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
615 			    size_t count)
616 {
617 	int rc;
618 
619 	rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
620 	return rc ? rc : count;
621 }
622 static DRIVER_ATTR_WO(uevent);
623 
driver_attach_async(void * _drv,async_cookie_t cookie)624 static void driver_attach_async(void *_drv, async_cookie_t cookie)
625 {
626 	struct device_driver *drv = _drv;
627 	int ret;
628 
629 	ret = driver_attach(drv);
630 
631 	pr_debug("bus: '%s': driver %s async attach completed: %d\n",
632 		 drv->bus->name, drv->name, ret);
633 }
634 
635 /**
636  * bus_add_driver - Add a driver to the bus.
637  * @drv: driver.
638  */
bus_add_driver(struct device_driver * drv)639 int bus_add_driver(struct device_driver *drv)
640 {
641 	struct bus_type *bus;
642 	struct driver_private *priv;
643 	int error = 0;
644 
645 	bus = bus_get(drv->bus);
646 	if (!bus)
647 		return -EINVAL;
648 
649 	pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
650 
651 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
652 	if (!priv) {
653 		error = -ENOMEM;
654 		goto out_put_bus;
655 	}
656 	klist_init(&priv->klist_devices, NULL, NULL);
657 	priv->driver = drv;
658 	drv->p = priv;
659 	priv->kobj.kset = bus->p->drivers_kset;
660 	error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
661 				     "%s", drv->name);
662 	if (error)
663 		goto out_unregister;
664 
665 	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
666 	if (drv->bus->p->drivers_autoprobe) {
667 		if (driver_allows_async_probing(drv)) {
668 			pr_debug("bus: '%s': probing driver %s asynchronously\n",
669 				drv->bus->name, drv->name);
670 			async_schedule(driver_attach_async, drv);
671 		} else {
672 			error = driver_attach(drv);
673 			if (error)
674 				goto out_unregister;
675 		}
676 	}
677 	module_add_driver(drv->owner, drv);
678 
679 	error = driver_create_file(drv, &driver_attr_uevent);
680 	if (error) {
681 		printk(KERN_ERR "%s: uevent attr (%s) failed\n",
682 			__func__, drv->name);
683 	}
684 	error = driver_add_groups(drv, bus->drv_groups);
685 	if (error) {
686 		/* How the hell do we get out of this pickle? Give up */
687 		printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
688 			__func__, drv->name);
689 	}
690 
691 	if (!drv->suppress_bind_attrs) {
692 		error = add_bind_files(drv);
693 		if (error) {
694 			/* Ditto */
695 			printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
696 				__func__, drv->name);
697 		}
698 	}
699 
700 	return 0;
701 
702 out_unregister:
703 	kobject_put(&priv->kobj);
704 	/* drv->p is freed in driver_release()  */
705 	drv->p = NULL;
706 out_put_bus:
707 	bus_put(bus);
708 	return error;
709 }
710 
711 /**
712  * bus_remove_driver - delete driver from bus's knowledge.
713  * @drv: driver.
714  *
715  * Detach the driver from the devices it controls, and remove
716  * it from its bus's list of drivers. Finally, we drop the reference
717  * to the bus we took in bus_add_driver().
718  */
bus_remove_driver(struct device_driver * drv)719 void bus_remove_driver(struct device_driver *drv)
720 {
721 	if (!drv->bus)
722 		return;
723 
724 	if (!drv->suppress_bind_attrs)
725 		remove_bind_files(drv);
726 	driver_remove_groups(drv, drv->bus->drv_groups);
727 	driver_remove_file(drv, &driver_attr_uevent);
728 	klist_remove(&drv->p->knode_bus);
729 	pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
730 	driver_detach(drv);
731 	module_remove_driver(drv);
732 	kobject_put(&drv->p->kobj);
733 	bus_put(drv->bus);
734 }
735 
736 /* Helper for bus_rescan_devices's iter */
bus_rescan_devices_helper(struct device * dev,void * data)737 static int __must_check bus_rescan_devices_helper(struct device *dev,
738 						  void *data)
739 {
740 	int ret = 0;
741 
742 	if (!dev->driver) {
743 		if (dev->parent && dev->bus->need_parent_lock)
744 			device_lock(dev->parent);
745 		ret = device_attach(dev);
746 		if (dev->parent && dev->bus->need_parent_lock)
747 			device_unlock(dev->parent);
748 	}
749 	return ret < 0 ? ret : 0;
750 }
751 
752 /**
753  * bus_rescan_devices - rescan devices on the bus for possible drivers
754  * @bus: the bus to scan.
755  *
756  * This function will look for devices on the bus with no driver
757  * attached and rescan it against existing drivers to see if it matches
758  * any by calling device_attach() for the unbound devices.
759  */
bus_rescan_devices(struct bus_type * bus)760 int bus_rescan_devices(struct bus_type *bus)
761 {
762 	return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
763 }
764 EXPORT_SYMBOL_GPL(bus_rescan_devices);
765 
766 /**
767  * device_reprobe - remove driver for a device and probe for a new driver
768  * @dev: the device to reprobe
769  *
770  * This function detaches the attached driver (if any) for the given
771  * device and restarts the driver probing process.  It is intended
772  * to use if probing criteria changed during a devices lifetime and
773  * driver attachment should change accordingly.
774  */
device_reprobe(struct device * dev)775 int device_reprobe(struct device *dev)
776 {
777 	if (dev->driver) {
778 		if (dev->parent && dev->bus->need_parent_lock)
779 			device_lock(dev->parent);
780 		device_release_driver(dev);
781 		if (dev->parent && dev->bus->need_parent_lock)
782 			device_unlock(dev->parent);
783 	}
784 	return bus_rescan_devices_helper(dev, NULL);
785 }
786 EXPORT_SYMBOL_GPL(device_reprobe);
787 
788 /**
789  * find_bus - locate bus by name.
790  * @name: name of bus.
791  *
792  * Call kset_find_obj() to iterate over list of buses to
793  * find a bus by name. Return bus if found.
794  *
795  * Note that kset_find_obj increments bus' reference count.
796  */
797 #if 0
798 struct bus_type *find_bus(char *name)
799 {
800 	struct kobject *k = kset_find_obj(bus_kset, name);
801 	return k ? to_bus(k) : NULL;
802 }
803 #endif  /*  0  */
804 
bus_add_groups(struct bus_type * bus,const struct attribute_group ** groups)805 static int bus_add_groups(struct bus_type *bus,
806 			  const struct attribute_group **groups)
807 {
808 	return sysfs_create_groups(&bus->p->subsys.kobj, groups);
809 }
810 
bus_remove_groups(struct bus_type * bus,const struct attribute_group ** groups)811 static void bus_remove_groups(struct bus_type *bus,
812 			      const struct attribute_group **groups)
813 {
814 	sysfs_remove_groups(&bus->p->subsys.kobj, groups);
815 }
816 
klist_devices_get(struct klist_node * n)817 static void klist_devices_get(struct klist_node *n)
818 {
819 	struct device_private *dev_prv = to_device_private_bus(n);
820 	struct device *dev = dev_prv->device;
821 
822 	get_device(dev);
823 }
824 
klist_devices_put(struct klist_node * n)825 static void klist_devices_put(struct klist_node *n)
826 {
827 	struct device_private *dev_prv = to_device_private_bus(n);
828 	struct device *dev = dev_prv->device;
829 
830 	put_device(dev);
831 }
832 
bus_uevent_store(struct bus_type * bus,const char * buf,size_t count)833 static ssize_t bus_uevent_store(struct bus_type *bus,
834 				const char *buf, size_t count)
835 {
836 	int rc;
837 
838 	rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
839 	return rc ? rc : count;
840 }
841 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
842 
843 /**
844  * bus_register - register a driver-core subsystem
845  * @bus: bus to register
846  *
847  * Once we have that, we register the bus with the kobject
848  * infrastructure, then register the children subsystems it has:
849  * the devices and drivers that belong to the subsystem.
850  */
bus_register(struct bus_type * bus)851 int bus_register(struct bus_type *bus)
852 {
853 	int retval;
854 	struct subsys_private *priv;
855 	struct lock_class_key *key = &bus->lock_key;
856 
857 	priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
858 	if (!priv)
859 		return -ENOMEM;
860 
861 	priv->bus = bus;
862 	bus->p = priv;
863 
864 	BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
865 
866 	retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
867 	if (retval)
868 		goto out;
869 
870 	priv->subsys.kobj.kset = bus_kset;
871 	priv->subsys.kobj.ktype = &bus_ktype;
872 	priv->drivers_autoprobe = 1;
873 
874 	retval = kset_register(&priv->subsys);
875 	if (retval)
876 		goto out;
877 
878 	retval = bus_create_file(bus, &bus_attr_uevent);
879 	if (retval)
880 		goto bus_uevent_fail;
881 
882 	priv->devices_kset = kset_create_and_add("devices", NULL,
883 						 &priv->subsys.kobj);
884 	if (!priv->devices_kset) {
885 		retval = -ENOMEM;
886 		goto bus_devices_fail;
887 	}
888 
889 	priv->drivers_kset = kset_create_and_add("drivers", NULL,
890 						 &priv->subsys.kobj);
891 	if (!priv->drivers_kset) {
892 		retval = -ENOMEM;
893 		goto bus_drivers_fail;
894 	}
895 
896 	INIT_LIST_HEAD(&priv->interfaces);
897 	__mutex_init(&priv->mutex, "subsys mutex", key);
898 	klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
899 	klist_init(&priv->klist_drivers, NULL, NULL);
900 
901 	retval = add_probe_files(bus);
902 	if (retval)
903 		goto bus_probe_files_fail;
904 
905 	retval = bus_add_groups(bus, bus->bus_groups);
906 	if (retval)
907 		goto bus_groups_fail;
908 
909 	pr_debug("bus: '%s': registered\n", bus->name);
910 	return 0;
911 
912 bus_groups_fail:
913 	remove_probe_files(bus);
914 bus_probe_files_fail:
915 	kset_unregister(bus->p->drivers_kset);
916 bus_drivers_fail:
917 	kset_unregister(bus->p->devices_kset);
918 bus_devices_fail:
919 	bus_remove_file(bus, &bus_attr_uevent);
920 bus_uevent_fail:
921 	kset_unregister(&bus->p->subsys);
922 out:
923 	kfree(bus->p);
924 	bus->p = NULL;
925 	return retval;
926 }
927 EXPORT_SYMBOL_GPL(bus_register);
928 
929 /**
930  * bus_unregister - remove a bus from the system
931  * @bus: bus.
932  *
933  * Unregister the child subsystems and the bus itself.
934  * Finally, we call bus_put() to release the refcount
935  */
bus_unregister(struct bus_type * bus)936 void bus_unregister(struct bus_type *bus)
937 {
938 	pr_debug("bus: '%s': unregistering\n", bus->name);
939 	if (bus->dev_root)
940 		device_unregister(bus->dev_root);
941 	bus_remove_groups(bus, bus->bus_groups);
942 	remove_probe_files(bus);
943 	kset_unregister(bus->p->drivers_kset);
944 	kset_unregister(bus->p->devices_kset);
945 	bus_remove_file(bus, &bus_attr_uevent);
946 	kset_unregister(&bus->p->subsys);
947 }
948 EXPORT_SYMBOL_GPL(bus_unregister);
949 
bus_register_notifier(struct bus_type * bus,struct notifier_block * nb)950 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
951 {
952 	return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
953 }
954 EXPORT_SYMBOL_GPL(bus_register_notifier);
955 
bus_unregister_notifier(struct bus_type * bus,struct notifier_block * nb)956 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
957 {
958 	return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
959 }
960 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
961 
bus_get_kset(struct bus_type * bus)962 struct kset *bus_get_kset(struct bus_type *bus)
963 {
964 	return &bus->p->subsys;
965 }
966 EXPORT_SYMBOL_GPL(bus_get_kset);
967 
bus_get_device_klist(struct bus_type * bus)968 struct klist *bus_get_device_klist(struct bus_type *bus)
969 {
970 	return &bus->p->klist_devices;
971 }
972 EXPORT_SYMBOL_GPL(bus_get_device_klist);
973 
974 /*
975  * Yes, this forcibly breaks the klist abstraction temporarily.  It
976  * just wants to sort the klist, not change reference counts and
977  * take/drop locks rapidly in the process.  It does all this while
978  * holding the lock for the list, so objects can't otherwise be
979  * added/removed while we're swizzling.
980  */
device_insertion_sort_klist(struct device * a,struct list_head * list,int (* compare)(const struct device * a,const struct device * b))981 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
982 					int (*compare)(const struct device *a,
983 							const struct device *b))
984 {
985 	struct klist_node *n;
986 	struct device_private *dev_prv;
987 	struct device *b;
988 
989 	list_for_each_entry(n, list, n_node) {
990 		dev_prv = to_device_private_bus(n);
991 		b = dev_prv->device;
992 		if (compare(a, b) <= 0) {
993 			list_move_tail(&a->p->knode_bus.n_node,
994 				       &b->p->knode_bus.n_node);
995 			return;
996 		}
997 	}
998 	list_move_tail(&a->p->knode_bus.n_node, list);
999 }
1000 
bus_sort_breadthfirst(struct bus_type * bus,int (* compare)(const struct device * a,const struct device * b))1001 void bus_sort_breadthfirst(struct bus_type *bus,
1002 			   int (*compare)(const struct device *a,
1003 					  const struct device *b))
1004 {
1005 	LIST_HEAD(sorted_devices);
1006 	struct klist_node *n, *tmp;
1007 	struct device_private *dev_prv;
1008 	struct device *dev;
1009 	struct klist *device_klist;
1010 
1011 	device_klist = bus_get_device_klist(bus);
1012 
1013 	spin_lock(&device_klist->k_lock);
1014 	list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1015 		dev_prv = to_device_private_bus(n);
1016 		dev = dev_prv->device;
1017 		device_insertion_sort_klist(dev, &sorted_devices, compare);
1018 	}
1019 	list_splice(&sorted_devices, &device_klist->k_list);
1020 	spin_unlock(&device_klist->k_lock);
1021 }
1022 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1023 
1024 /**
1025  * subsys_dev_iter_init - initialize subsys device iterator
1026  * @iter: subsys iterator to initialize
1027  * @subsys: the subsys we wanna iterate over
1028  * @start: the device to start iterating from, if any
1029  * @type: device_type of the devices to iterate over, NULL for all
1030  *
1031  * Initialize subsys iterator @iter such that it iterates over devices
1032  * of @subsys.  If @start is set, the list iteration will start there,
1033  * otherwise if it is NULL, the iteration starts at the beginning of
1034  * the list.
1035  */
subsys_dev_iter_init(struct subsys_dev_iter * iter,struct bus_type * subsys,struct device * start,const struct device_type * type)1036 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1037 			  struct device *start, const struct device_type *type)
1038 {
1039 	struct klist_node *start_knode = NULL;
1040 
1041 	if (start)
1042 		start_knode = &start->p->knode_bus;
1043 	klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1044 	iter->type = type;
1045 }
1046 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1047 
1048 /**
1049  * subsys_dev_iter_next - iterate to the next device
1050  * @iter: subsys iterator to proceed
1051  *
1052  * Proceed @iter to the next device and return it.  Returns NULL if
1053  * iteration is complete.
1054  *
1055  * The returned device is referenced and won't be released till
1056  * iterator is proceed to the next device or exited.  The caller is
1057  * free to do whatever it wants to do with the device including
1058  * calling back into subsys code.
1059  */
subsys_dev_iter_next(struct subsys_dev_iter * iter)1060 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1061 {
1062 	struct klist_node *knode;
1063 	struct device *dev;
1064 
1065 	for (;;) {
1066 		knode = klist_next(&iter->ki);
1067 		if (!knode)
1068 			return NULL;
1069 		dev = to_device_private_bus(knode)->device;
1070 		if (!iter->type || iter->type == dev->type)
1071 			return dev;
1072 	}
1073 }
1074 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1075 
1076 /**
1077  * subsys_dev_iter_exit - finish iteration
1078  * @iter: subsys iterator to finish
1079  *
1080  * Finish an iteration.  Always call this function after iteration is
1081  * complete whether the iteration ran till the end or not.
1082  */
subsys_dev_iter_exit(struct subsys_dev_iter * iter)1083 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1084 {
1085 	klist_iter_exit(&iter->ki);
1086 }
1087 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1088 
subsys_interface_register(struct subsys_interface * sif)1089 int subsys_interface_register(struct subsys_interface *sif)
1090 {
1091 	struct bus_type *subsys;
1092 	struct subsys_dev_iter iter;
1093 	struct device *dev;
1094 
1095 	if (!sif || !sif->subsys)
1096 		return -ENODEV;
1097 
1098 	subsys = bus_get(sif->subsys);
1099 	if (!subsys)
1100 		return -EINVAL;
1101 
1102 	mutex_lock(&subsys->p->mutex);
1103 	list_add_tail(&sif->node, &subsys->p->interfaces);
1104 	if (sif->add_dev) {
1105 		subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1106 		while ((dev = subsys_dev_iter_next(&iter)))
1107 			sif->add_dev(dev, sif);
1108 		subsys_dev_iter_exit(&iter);
1109 	}
1110 	mutex_unlock(&subsys->p->mutex);
1111 
1112 	return 0;
1113 }
1114 EXPORT_SYMBOL_GPL(subsys_interface_register);
1115 
subsys_interface_unregister(struct subsys_interface * sif)1116 void subsys_interface_unregister(struct subsys_interface *sif)
1117 {
1118 	struct bus_type *subsys;
1119 	struct subsys_dev_iter iter;
1120 	struct device *dev;
1121 
1122 	if (!sif || !sif->subsys)
1123 		return;
1124 
1125 	subsys = sif->subsys;
1126 
1127 	mutex_lock(&subsys->p->mutex);
1128 	list_del_init(&sif->node);
1129 	if (sif->remove_dev) {
1130 		subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1131 		while ((dev = subsys_dev_iter_next(&iter)))
1132 			sif->remove_dev(dev, sif);
1133 		subsys_dev_iter_exit(&iter);
1134 	}
1135 	mutex_unlock(&subsys->p->mutex);
1136 
1137 	bus_put(subsys);
1138 }
1139 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1140 
system_root_device_release(struct device * dev)1141 static void system_root_device_release(struct device *dev)
1142 {
1143 	kfree(dev);
1144 }
1145 
subsys_register(struct bus_type * subsys,const struct attribute_group ** groups,struct kobject * parent_of_root)1146 static int subsys_register(struct bus_type *subsys,
1147 			   const struct attribute_group **groups,
1148 			   struct kobject *parent_of_root)
1149 {
1150 	struct device *dev;
1151 	int err;
1152 
1153 	err = bus_register(subsys);
1154 	if (err < 0)
1155 		return err;
1156 
1157 	dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1158 	if (!dev) {
1159 		err = -ENOMEM;
1160 		goto err_dev;
1161 	}
1162 
1163 	err = dev_set_name(dev, "%s", subsys->name);
1164 	if (err < 0)
1165 		goto err_name;
1166 
1167 	dev->kobj.parent = parent_of_root;
1168 	dev->groups = groups;
1169 	dev->release = system_root_device_release;
1170 
1171 	err = device_register(dev);
1172 	if (err < 0)
1173 		goto err_dev_reg;
1174 
1175 	subsys->dev_root = dev;
1176 	return 0;
1177 
1178 err_dev_reg:
1179 	put_device(dev);
1180 	dev = NULL;
1181 err_name:
1182 	kfree(dev);
1183 err_dev:
1184 	bus_unregister(subsys);
1185 	return err;
1186 }
1187 
1188 /**
1189  * subsys_system_register - register a subsystem at /sys/devices/system/
1190  * @subsys: system subsystem
1191  * @groups: default attributes for the root device
1192  *
1193  * All 'system' subsystems have a /sys/devices/system/<name> root device
1194  * with the name of the subsystem. The root device can carry subsystem-
1195  * wide attributes. All registered devices are below this single root
1196  * device and are named after the subsystem with a simple enumeration
1197  * number appended. The registered devices are not explicitly named;
1198  * only 'id' in the device needs to be set.
1199  *
1200  * Do not use this interface for anything new, it exists for compatibility
1201  * with bad ideas only. New subsystems should use plain subsystems; and
1202  * add the subsystem-wide attributes should be added to the subsystem
1203  * directory itself and not some create fake root-device placed in
1204  * /sys/devices/system/<name>.
1205  */
subsys_system_register(struct bus_type * subsys,const struct attribute_group ** groups)1206 int subsys_system_register(struct bus_type *subsys,
1207 			   const struct attribute_group **groups)
1208 {
1209 	return subsys_register(subsys, groups, &system_kset->kobj);
1210 }
1211 EXPORT_SYMBOL_GPL(subsys_system_register);
1212 
1213 /**
1214  * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1215  * @subsys: virtual subsystem
1216  * @groups: default attributes for the root device
1217  *
1218  * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1219  * with the name of the subystem.  The root device can carry subsystem-wide
1220  * attributes.  All registered devices are below this single root device.
1221  * There's no restriction on device naming.  This is for kernel software
1222  * constructs which need sysfs interface.
1223  */
subsys_virtual_register(struct bus_type * subsys,const struct attribute_group ** groups)1224 int subsys_virtual_register(struct bus_type *subsys,
1225 			    const struct attribute_group **groups)
1226 {
1227 	struct kobject *virtual_dir;
1228 
1229 	virtual_dir = virtual_device_parent(NULL);
1230 	if (!virtual_dir)
1231 		return -ENOMEM;
1232 
1233 	return subsys_register(subsys, groups, virtual_dir);
1234 }
1235 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1236 
buses_init(void)1237 int __init buses_init(void)
1238 {
1239 	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1240 	if (!bus_kset)
1241 		return -ENOMEM;
1242 
1243 	system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1244 	if (!system_kset)
1245 		return -ENOMEM;
1246 
1247 	return 0;
1248 }
1249