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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/bus.h>
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 <linux/sysfs.h>
21#include "base.h"
22#include "power/power.h"
23
24/* /sys/devices/system */
25static struct kset *system_kset;
26
27#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
28
29/*
30 * sysfs bindings for drivers
31 */
32
33#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
34
35#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
36 struct driver_attribute driver_attr_##_name = \
37 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
38
39static int __must_check bus_rescan_devices_helper(struct device *dev,
40 void *data);
41
42static struct bus_type *bus_get(struct bus_type *bus)
43{
44 if (bus) {
45 kset_get(&bus->p->subsys);
46 return bus;
47 }
48 return NULL;
49}
50
51static void bus_put(struct bus_type *bus)
52{
53 if (bus)
54 kset_put(&bus->p->subsys);
55}
56
57static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
58 char *buf)
59{
60 struct driver_attribute *drv_attr = to_drv_attr(attr);
61 struct driver_private *drv_priv = to_driver(kobj);
62 ssize_t ret = -EIO;
63
64 if (drv_attr->show)
65 ret = drv_attr->show(drv_priv->driver, buf);
66 return ret;
67}
68
69static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
70 const char *buf, size_t count)
71{
72 struct driver_attribute *drv_attr = to_drv_attr(attr);
73 struct driver_private *drv_priv = to_driver(kobj);
74 ssize_t ret = -EIO;
75
76 if (drv_attr->store)
77 ret = drv_attr->store(drv_priv->driver, buf, count);
78 return ret;
79}
80
81static const struct sysfs_ops driver_sysfs_ops = {
82 .show = drv_attr_show,
83 .store = drv_attr_store,
84};
85
86static void driver_release(struct kobject *kobj)
87{
88 struct driver_private *drv_priv = to_driver(kobj);
89
90 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
91 kfree(drv_priv);
92}
93
94static struct kobj_type driver_ktype = {
95 .sysfs_ops = &driver_sysfs_ops,
96 .release = driver_release,
97};
98
99/*
100 * sysfs bindings for buses
101 */
102static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
103 char *buf)
104{
105 struct bus_attribute *bus_attr = to_bus_attr(attr);
106 struct subsys_private *subsys_priv = to_subsys_private(kobj);
107 ssize_t ret = 0;
108
109 if (bus_attr->show)
110 ret = bus_attr->show(subsys_priv->bus, buf);
111 return ret;
112}
113
114static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
115 const char *buf, size_t count)
116{
117 struct bus_attribute *bus_attr = to_bus_attr(attr);
118 struct subsys_private *subsys_priv = to_subsys_private(kobj);
119 ssize_t ret = 0;
120
121 if (bus_attr->store)
122 ret = bus_attr->store(subsys_priv->bus, buf, count);
123 return ret;
124}
125
126static const struct sysfs_ops bus_sysfs_ops = {
127 .show = bus_attr_show,
128 .store = bus_attr_store,
129};
130
131int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
132{
133 int error;
134 if (bus_get(bus)) {
135 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
136 bus_put(bus);
137 } else
138 error = -EINVAL;
139 return error;
140}
141EXPORT_SYMBOL_GPL(bus_create_file);
142
143void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
144{
145 if (bus_get(bus)) {
146 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
147 bus_put(bus);
148 }
149}
150EXPORT_SYMBOL_GPL(bus_remove_file);
151
152static void bus_release(struct kobject *kobj)
153{
154 struct subsys_private *priv = to_subsys_private(kobj);
155 struct bus_type *bus = priv->bus;
156
157 kfree(priv);
158 bus->p = NULL;
159}
160
161static struct kobj_type bus_ktype = {
162 .sysfs_ops = &bus_sysfs_ops,
163 .release = bus_release,
164};
165
166static int bus_uevent_filter(const struct kobject *kobj)
167{
168 const struct kobj_type *ktype = get_ktype(kobj);
169
170 if (ktype == &bus_ktype)
171 return 1;
172 return 0;
173}
174
175static const struct kset_uevent_ops bus_uevent_ops = {
176 .filter = bus_uevent_filter,
177};
178
179static struct kset *bus_kset;
180
181/* Manually detach a device from its associated driver. */
182static ssize_t unbind_store(struct device_driver *drv, const char *buf,
183 size_t count)
184{
185 struct bus_type *bus = bus_get(drv->bus);
186 struct device *dev;
187 int err = -ENODEV;
188
189 dev = bus_find_device_by_name(bus, NULL, buf);
190 if (dev && dev->driver == drv) {
191 device_driver_detach(dev);
192 err = count;
193 }
194 put_device(dev);
195 bus_put(bus);
196 return err;
197}
198static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
199
200/*
201 * Manually attach a device to a driver.
202 * Note: the driver must want to bind to the device,
203 * it is not possible to override the driver's id table.
204 */
205static ssize_t bind_store(struct device_driver *drv, const char *buf,
206 size_t count)
207{
208 struct bus_type *bus = bus_get(drv->bus);
209 struct device *dev;
210 int err = -ENODEV;
211
212 dev = bus_find_device_by_name(bus, NULL, buf);
213 if (dev && driver_match_device(drv, dev)) {
214 err = device_driver_attach(drv, dev);
215 if (!err) {
216 /* success */
217 err = count;
218 }
219 }
220 put_device(dev);
221 bus_put(bus);
222 return err;
223}
224static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
225
226static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
227{
228 return sysfs_emit(buf, "%d\n", bus->p->drivers_autoprobe);
229}
230
231static ssize_t drivers_autoprobe_store(struct bus_type *bus,
232 const char *buf, size_t count)
233{
234 if (buf[0] == '0')
235 bus->p->drivers_autoprobe = 0;
236 else
237 bus->p->drivers_autoprobe = 1;
238 return count;
239}
240
241static ssize_t drivers_probe_store(struct bus_type *bus,
242 const char *buf, size_t count)
243{
244 struct device *dev;
245 int err = -EINVAL;
246
247 dev = bus_find_device_by_name(bus, NULL, buf);
248 if (!dev)
249 return -ENODEV;
250 if (bus_rescan_devices_helper(dev, NULL) == 0)
251 err = count;
252 put_device(dev);
253 return err;
254}
255
256static struct device *next_device(struct klist_iter *i)
257{
258 struct klist_node *n = klist_next(i);
259 struct device *dev = NULL;
260 struct device_private *dev_prv;
261
262 if (n) {
263 dev_prv = to_device_private_bus(n);
264 dev = dev_prv->device;
265 }
266 return dev;
267}
268
269/**
270 * bus_for_each_dev - device iterator.
271 * @bus: bus type.
272 * @start: device to start iterating from.
273 * @data: data for the callback.
274 * @fn: function to be called for each device.
275 *
276 * Iterate over @bus's list of devices, and call @fn for each,
277 * passing it @data. If @start is not NULL, we use that device to
278 * begin iterating from.
279 *
280 * We check the return of @fn each time. If it returns anything
281 * other than 0, we break out and return that value.
282 *
283 * NOTE: The device that returns a non-zero value is not retained
284 * in any way, nor is its refcount incremented. If the caller needs
285 * to retain this data, it should do so, and increment the reference
286 * count in the supplied callback.
287 */
288int bus_for_each_dev(struct bus_type *bus, struct device *start,
289 void *data, int (*fn)(struct device *, void *))
290{
291 struct klist_iter i;
292 struct device *dev;
293 int error = 0;
294
295 if (!bus || !bus->p)
296 return -EINVAL;
297
298 klist_iter_init_node(&bus->p->klist_devices, &i,
299 (start ? &start->p->knode_bus : NULL));
300 while (!error && (dev = next_device(&i)))
301 error = fn(dev, data);
302 klist_iter_exit(&i);
303 return error;
304}
305EXPORT_SYMBOL_GPL(bus_for_each_dev);
306
307/**
308 * bus_find_device - device iterator for locating a particular device.
309 * @bus: bus type
310 * @start: Device to begin with
311 * @data: Data to pass to match function
312 * @match: Callback function to check device
313 *
314 * This is similar to the bus_for_each_dev() function above, but it
315 * returns a reference to a device that is 'found' for later use, as
316 * determined by the @match callback.
317 *
318 * The callback should return 0 if the device doesn't match and non-zero
319 * if it does. If the callback returns non-zero, this function will
320 * return to the caller and not iterate over any more devices.
321 */
322struct device *bus_find_device(struct bus_type *bus,
323 struct device *start, const void *data,
324 int (*match)(struct device *dev, const void *data))
325{
326 struct klist_iter i;
327 struct device *dev;
328
329 if (!bus || !bus->p)
330 return NULL;
331
332 klist_iter_init_node(&bus->p->klist_devices, &i,
333 (start ? &start->p->knode_bus : NULL));
334 while ((dev = next_device(&i)))
335 if (match(dev, data) && get_device(dev))
336 break;
337 klist_iter_exit(&i);
338 return dev;
339}
340EXPORT_SYMBOL_GPL(bus_find_device);
341
342/**
343 * subsys_find_device_by_id - find a device with a specific enumeration number
344 * @subsys: subsystem
345 * @id: index 'id' in struct device
346 * @hint: device to check first
347 *
348 * Check the hint's next object and if it is a match return it directly,
349 * otherwise, fall back to a full list search. Either way a reference for
350 * the returned object is taken.
351 */
352struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
353 struct device *hint)
354{
355 struct klist_iter i;
356 struct device *dev;
357
358 if (!subsys)
359 return NULL;
360
361 if (hint) {
362 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
363 dev = next_device(&i);
364 if (dev && dev->id == id && get_device(dev)) {
365 klist_iter_exit(&i);
366 return dev;
367 }
368 klist_iter_exit(&i);
369 }
370
371 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
372 while ((dev = next_device(&i))) {
373 if (dev->id == id && get_device(dev)) {
374 klist_iter_exit(&i);
375 return dev;
376 }
377 }
378 klist_iter_exit(&i);
379 return NULL;
380}
381EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
382
383static struct device_driver *next_driver(struct klist_iter *i)
384{
385 struct klist_node *n = klist_next(i);
386 struct driver_private *drv_priv;
387
388 if (n) {
389 drv_priv = container_of(n, struct driver_private, knode_bus);
390 return drv_priv->driver;
391 }
392 return NULL;
393}
394
395/**
396 * bus_for_each_drv - driver iterator
397 * @bus: bus we're dealing with.
398 * @start: driver to start iterating on.
399 * @data: data to pass to the callback.
400 * @fn: function to call for each driver.
401 *
402 * This is nearly identical to the device iterator above.
403 * We iterate over each driver that belongs to @bus, and call
404 * @fn for each. If @fn returns anything but 0, we break out
405 * and return it. If @start is not NULL, we use it as the head
406 * of the list.
407 *
408 * NOTE: we don't return the driver that returns a non-zero
409 * value, nor do we leave the reference count incremented for that
410 * driver. If the caller needs to know that info, it must set it
411 * in the callback. It must also be sure to increment the refcount
412 * so it doesn't disappear before returning to the caller.
413 */
414int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
415 void *data, int (*fn)(struct device_driver *, void *))
416{
417 struct klist_iter i;
418 struct device_driver *drv;
419 int error = 0;
420
421 if (!bus)
422 return -EINVAL;
423
424 klist_iter_init_node(&bus->p->klist_drivers, &i,
425 start ? &start->p->knode_bus : NULL);
426 while ((drv = next_driver(&i)) && !error)
427 error = fn(drv, data);
428 klist_iter_exit(&i);
429 return error;
430}
431EXPORT_SYMBOL_GPL(bus_for_each_drv);
432
433/**
434 * bus_add_device - add device to bus
435 * @dev: device being added
436 *
437 * - Add device's bus attributes.
438 * - Create links to device's bus.
439 * - Add the device to its bus's list of devices.
440 */
441int bus_add_device(struct device *dev)
442{
443 struct bus_type *bus = bus_get(dev->bus);
444 int error = 0;
445
446 if (bus) {
447 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
448 error = device_add_groups(dev, bus->dev_groups);
449 if (error)
450 goto out_put;
451 error = sysfs_create_link(&bus->p->devices_kset->kobj,
452 &dev->kobj, dev_name(dev));
453 if (error)
454 goto out_groups;
455 error = sysfs_create_link(&dev->kobj,
456 &dev->bus->p->subsys.kobj, "subsystem");
457 if (error)
458 goto out_subsys;
459 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
460 }
461 return 0;
462
463out_subsys:
464 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
465out_groups:
466 device_remove_groups(dev, bus->dev_groups);
467out_put:
468 bus_put(dev->bus);
469 return error;
470}
471
472/**
473 * bus_probe_device - probe drivers for a new device
474 * @dev: device to probe
475 *
476 * - Automatically probe for a driver if the bus allows it.
477 */
478void bus_probe_device(struct device *dev)
479{
480 struct bus_type *bus = dev->bus;
481 struct subsys_interface *sif;
482
483 if (!bus)
484 return;
485
486 if (bus->p->drivers_autoprobe)
487 device_initial_probe(dev);
488
489 mutex_lock(&bus->p->mutex);
490 list_for_each_entry(sif, &bus->p->interfaces, node)
491 if (sif->add_dev)
492 sif->add_dev(dev, sif);
493 mutex_unlock(&bus->p->mutex);
494}
495
496/**
497 * bus_remove_device - remove device from bus
498 * @dev: device to be removed
499 *
500 * - Remove device from all interfaces.
501 * - Remove symlink from bus' directory.
502 * - Delete device from bus's list.
503 * - Detach from its driver.
504 * - Drop reference taken in bus_add_device().
505 */
506void bus_remove_device(struct device *dev)
507{
508 struct bus_type *bus = dev->bus;
509 struct subsys_interface *sif;
510
511 if (!bus)
512 return;
513
514 mutex_lock(&bus->p->mutex);
515 list_for_each_entry(sif, &bus->p->interfaces, node)
516 if (sif->remove_dev)
517 sif->remove_dev(dev, sif);
518 mutex_unlock(&bus->p->mutex);
519
520 sysfs_remove_link(&dev->kobj, "subsystem");
521 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
522 dev_name(dev));
523 device_remove_groups(dev, dev->bus->dev_groups);
524 if (klist_node_attached(&dev->p->knode_bus))
525 klist_del(&dev->p->knode_bus);
526
527 pr_debug("bus: '%s': remove device %s\n",
528 dev->bus->name, dev_name(dev));
529 device_release_driver(dev);
530 bus_put(dev->bus);
531}
532
533static int __must_check add_bind_files(struct device_driver *drv)
534{
535 int ret;
536
537 ret = driver_create_file(drv, &driver_attr_unbind);
538 if (ret == 0) {
539 ret = driver_create_file(drv, &driver_attr_bind);
540 if (ret)
541 driver_remove_file(drv, &driver_attr_unbind);
542 }
543 return ret;
544}
545
546static void remove_bind_files(struct device_driver *drv)
547{
548 driver_remove_file(drv, &driver_attr_bind);
549 driver_remove_file(drv, &driver_attr_unbind);
550}
551
552static BUS_ATTR_WO(drivers_probe);
553static BUS_ATTR_RW(drivers_autoprobe);
554
555static int add_probe_files(struct bus_type *bus)
556{
557 int retval;
558
559 retval = bus_create_file(bus, &bus_attr_drivers_probe);
560 if (retval)
561 goto out;
562
563 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
564 if (retval)
565 bus_remove_file(bus, &bus_attr_drivers_probe);
566out:
567 return retval;
568}
569
570static void remove_probe_files(struct bus_type *bus)
571{
572 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
573 bus_remove_file(bus, &bus_attr_drivers_probe);
574}
575
576static ssize_t uevent_store(struct device_driver *drv, const char *buf,
577 size_t count)
578{
579 int rc;
580
581 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
582 return rc ? rc : count;
583}
584static DRIVER_ATTR_WO(uevent);
585
586/**
587 * bus_add_driver - Add a driver to the bus.
588 * @drv: driver.
589 */
590int bus_add_driver(struct device_driver *drv)
591{
592 struct bus_type *bus;
593 struct driver_private *priv;
594 int error = 0;
595
596 bus = bus_get(drv->bus);
597 if (!bus)
598 return -EINVAL;
599
600 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
601
602 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
603 if (!priv) {
604 error = -ENOMEM;
605 goto out_put_bus;
606 }
607 klist_init(&priv->klist_devices, NULL, NULL);
608 priv->driver = drv;
609 drv->p = priv;
610 priv->kobj.kset = bus->p->drivers_kset;
611 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
612 "%s", drv->name);
613 if (error)
614 goto out_unregister;
615
616 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
617 if (drv->bus->p->drivers_autoprobe) {
618 error = driver_attach(drv);
619 if (error)
620 goto out_del_list;
621 }
622 module_add_driver(drv->owner, drv);
623
624 error = driver_create_file(drv, &driver_attr_uevent);
625 if (error) {
626 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
627 __func__, drv->name);
628 }
629 error = driver_add_groups(drv, bus->drv_groups);
630 if (error) {
631 /* How the hell do we get out of this pickle? Give up */
632 printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
633 __func__, drv->name);
634 }
635
636 if (!drv->suppress_bind_attrs) {
637 error = add_bind_files(drv);
638 if (error) {
639 /* Ditto */
640 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
641 __func__, drv->name);
642 }
643 }
644
645 return 0;
646
647out_del_list:
648 klist_del(&priv->knode_bus);
649out_unregister:
650 kobject_put(&priv->kobj);
651 /* drv->p is freed in driver_release() */
652 drv->p = NULL;
653out_put_bus:
654 bus_put(bus);
655 return error;
656}
657
658/**
659 * bus_remove_driver - delete driver from bus's knowledge.
660 * @drv: driver.
661 *
662 * Detach the driver from the devices it controls, and remove
663 * it from its bus's list of drivers. Finally, we drop the reference
664 * to the bus we took in bus_add_driver().
665 */
666void bus_remove_driver(struct device_driver *drv)
667{
668 if (!drv->bus)
669 return;
670
671 if (!drv->suppress_bind_attrs)
672 remove_bind_files(drv);
673 driver_remove_groups(drv, drv->bus->drv_groups);
674 driver_remove_file(drv, &driver_attr_uevent);
675 klist_remove(&drv->p->knode_bus);
676 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
677 driver_detach(drv);
678 module_remove_driver(drv);
679 kobject_put(&drv->p->kobj);
680 bus_put(drv->bus);
681}
682
683/* Helper for bus_rescan_devices's iter */
684static int __must_check bus_rescan_devices_helper(struct device *dev,
685 void *data)
686{
687 int ret = 0;
688
689 if (!dev->driver) {
690 if (dev->parent && dev->bus->need_parent_lock)
691 device_lock(dev->parent);
692 ret = device_attach(dev);
693 if (dev->parent && dev->bus->need_parent_lock)
694 device_unlock(dev->parent);
695 }
696 return ret < 0 ? ret : 0;
697}
698
699/**
700 * bus_rescan_devices - rescan devices on the bus for possible drivers
701 * @bus: the bus to scan.
702 *
703 * This function will look for devices on the bus with no driver
704 * attached and rescan it against existing drivers to see if it matches
705 * any by calling device_attach() for the unbound devices.
706 */
707int bus_rescan_devices(struct bus_type *bus)
708{
709 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
710}
711EXPORT_SYMBOL_GPL(bus_rescan_devices);
712
713/**
714 * device_reprobe - remove driver for a device and probe for a new driver
715 * @dev: the device to reprobe
716 *
717 * This function detaches the attached driver (if any) for the given
718 * device and restarts the driver probing process. It is intended
719 * to use if probing criteria changed during a devices lifetime and
720 * driver attachment should change accordingly.
721 */
722int device_reprobe(struct device *dev)
723{
724 if (dev->driver)
725 device_driver_detach(dev);
726 return bus_rescan_devices_helper(dev, NULL);
727}
728EXPORT_SYMBOL_GPL(device_reprobe);
729
730static int bus_add_groups(struct bus_type *bus,
731 const struct attribute_group **groups)
732{
733 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
734}
735
736static void bus_remove_groups(struct bus_type *bus,
737 const struct attribute_group **groups)
738{
739 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
740}
741
742static void klist_devices_get(struct klist_node *n)
743{
744 struct device_private *dev_prv = to_device_private_bus(n);
745 struct device *dev = dev_prv->device;
746
747 get_device(dev);
748}
749
750static void klist_devices_put(struct klist_node *n)
751{
752 struct device_private *dev_prv = to_device_private_bus(n);
753 struct device *dev = dev_prv->device;
754
755 put_device(dev);
756}
757
758static ssize_t bus_uevent_store(struct bus_type *bus,
759 const char *buf, size_t count)
760{
761 int rc;
762
763 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
764 return rc ? rc : count;
765}
766/*
767 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
768 * here, but can not use it as earlier in the file we have
769 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
770 * function name.
771 */
772static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
773 bus_uevent_store);
774
775/**
776 * bus_register - register a driver-core subsystem
777 * @bus: bus to register
778 *
779 * Once we have that, we register the bus with the kobject
780 * infrastructure, then register the children subsystems it has:
781 * the devices and drivers that belong to the subsystem.
782 */
783int bus_register(struct bus_type *bus)
784{
785 int retval;
786 struct subsys_private *priv;
787 struct lock_class_key *key = &bus->lock_key;
788
789 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
790 if (!priv)
791 return -ENOMEM;
792
793 priv->bus = bus;
794 bus->p = priv;
795
796 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
797
798 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
799 if (retval)
800 goto out;
801
802 priv->subsys.kobj.kset = bus_kset;
803 priv->subsys.kobj.ktype = &bus_ktype;
804 priv->drivers_autoprobe = 1;
805
806 retval = kset_register(&priv->subsys);
807 if (retval)
808 goto out;
809
810 retval = bus_create_file(bus, &bus_attr_uevent);
811 if (retval)
812 goto bus_uevent_fail;
813
814 priv->devices_kset = kset_create_and_add("devices", NULL,
815 &priv->subsys.kobj);
816 if (!priv->devices_kset) {
817 retval = -ENOMEM;
818 goto bus_devices_fail;
819 }
820
821 priv->drivers_kset = kset_create_and_add("drivers", NULL,
822 &priv->subsys.kobj);
823 if (!priv->drivers_kset) {
824 retval = -ENOMEM;
825 goto bus_drivers_fail;
826 }
827
828 INIT_LIST_HEAD(&priv->interfaces);
829 __mutex_init(&priv->mutex, "subsys mutex", key);
830 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
831 klist_init(&priv->klist_drivers, NULL, NULL);
832
833 retval = add_probe_files(bus);
834 if (retval)
835 goto bus_probe_files_fail;
836
837 retval = bus_add_groups(bus, bus->bus_groups);
838 if (retval)
839 goto bus_groups_fail;
840
841 pr_debug("bus: '%s': registered\n", bus->name);
842 return 0;
843
844bus_groups_fail:
845 remove_probe_files(bus);
846bus_probe_files_fail:
847 kset_unregister(bus->p->drivers_kset);
848bus_drivers_fail:
849 kset_unregister(bus->p->devices_kset);
850bus_devices_fail:
851 bus_remove_file(bus, &bus_attr_uevent);
852bus_uevent_fail:
853 kset_unregister(&bus->p->subsys);
854out:
855 kfree(bus->p);
856 bus->p = NULL;
857 return retval;
858}
859EXPORT_SYMBOL_GPL(bus_register);
860
861/**
862 * bus_unregister - remove a bus from the system
863 * @bus: bus.
864 *
865 * Unregister the child subsystems and the bus itself.
866 * Finally, we call bus_put() to release the refcount
867 */
868void bus_unregister(struct bus_type *bus)
869{
870 pr_debug("bus: '%s': unregistering\n", bus->name);
871 if (bus->dev_root)
872 device_unregister(bus->dev_root);
873 bus_remove_groups(bus, bus->bus_groups);
874 remove_probe_files(bus);
875 kset_unregister(bus->p->drivers_kset);
876 kset_unregister(bus->p->devices_kset);
877 bus_remove_file(bus, &bus_attr_uevent);
878 kset_unregister(&bus->p->subsys);
879}
880EXPORT_SYMBOL_GPL(bus_unregister);
881
882int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
883{
884 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
885}
886EXPORT_SYMBOL_GPL(bus_register_notifier);
887
888int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
889{
890 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
891}
892EXPORT_SYMBOL_GPL(bus_unregister_notifier);
893
894struct kset *bus_get_kset(struct bus_type *bus)
895{
896 return &bus->p->subsys;
897}
898EXPORT_SYMBOL_GPL(bus_get_kset);
899
900struct klist *bus_get_device_klist(struct bus_type *bus)
901{
902 return &bus->p->klist_devices;
903}
904EXPORT_SYMBOL_GPL(bus_get_device_klist);
905
906/*
907 * Yes, this forcibly breaks the klist abstraction temporarily. It
908 * just wants to sort the klist, not change reference counts and
909 * take/drop locks rapidly in the process. It does all this while
910 * holding the lock for the list, so objects can't otherwise be
911 * added/removed while we're swizzling.
912 */
913static void device_insertion_sort_klist(struct device *a, struct list_head *list,
914 int (*compare)(const struct device *a,
915 const struct device *b))
916{
917 struct klist_node *n;
918 struct device_private *dev_prv;
919 struct device *b;
920
921 list_for_each_entry(n, list, n_node) {
922 dev_prv = to_device_private_bus(n);
923 b = dev_prv->device;
924 if (compare(a, b) <= 0) {
925 list_move_tail(&a->p->knode_bus.n_node,
926 &b->p->knode_bus.n_node);
927 return;
928 }
929 }
930 list_move_tail(&a->p->knode_bus.n_node, list);
931}
932
933void bus_sort_breadthfirst(struct bus_type *bus,
934 int (*compare)(const struct device *a,
935 const struct device *b))
936{
937 LIST_HEAD(sorted_devices);
938 struct klist_node *n, *tmp;
939 struct device_private *dev_prv;
940 struct device *dev;
941 struct klist *device_klist;
942
943 device_klist = bus_get_device_klist(bus);
944
945 spin_lock(&device_klist->k_lock);
946 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
947 dev_prv = to_device_private_bus(n);
948 dev = dev_prv->device;
949 device_insertion_sort_klist(dev, &sorted_devices, compare);
950 }
951 list_splice(&sorted_devices, &device_klist->k_list);
952 spin_unlock(&device_klist->k_lock);
953}
954EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
955
956/**
957 * subsys_dev_iter_init - initialize subsys device iterator
958 * @iter: subsys iterator to initialize
959 * @subsys: the subsys we wanna iterate over
960 * @start: the device to start iterating from, if any
961 * @type: device_type of the devices to iterate over, NULL for all
962 *
963 * Initialize subsys iterator @iter such that it iterates over devices
964 * of @subsys. If @start is set, the list iteration will start there,
965 * otherwise if it is NULL, the iteration starts at the beginning of
966 * the list.
967 */
968void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
969 struct device *start, const struct device_type *type)
970{
971 struct klist_node *start_knode = NULL;
972
973 if (start)
974 start_knode = &start->p->knode_bus;
975 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
976 iter->type = type;
977}
978EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
979
980/**
981 * subsys_dev_iter_next - iterate to the next device
982 * @iter: subsys iterator to proceed
983 *
984 * Proceed @iter to the next device and return it. Returns NULL if
985 * iteration is complete.
986 *
987 * The returned device is referenced and won't be released till
988 * iterator is proceed to the next device or exited. The caller is
989 * free to do whatever it wants to do with the device including
990 * calling back into subsys code.
991 */
992struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
993{
994 struct klist_node *knode;
995 struct device *dev;
996
997 for (;;) {
998 knode = klist_next(&iter->ki);
999 if (!knode)
1000 return NULL;
1001 dev = to_device_private_bus(knode)->device;
1002 if (!iter->type || iter->type == dev->type)
1003 return dev;
1004 }
1005}
1006EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1007
1008/**
1009 * subsys_dev_iter_exit - finish iteration
1010 * @iter: subsys iterator to finish
1011 *
1012 * Finish an iteration. Always call this function after iteration is
1013 * complete whether the iteration ran till the end or not.
1014 */
1015void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1016{
1017 klist_iter_exit(&iter->ki);
1018}
1019EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1020
1021int subsys_interface_register(struct subsys_interface *sif)
1022{
1023 struct bus_type *subsys;
1024 struct subsys_dev_iter iter;
1025 struct device *dev;
1026
1027 if (!sif || !sif->subsys)
1028 return -ENODEV;
1029
1030 subsys = bus_get(sif->subsys);
1031 if (!subsys)
1032 return -EINVAL;
1033
1034 mutex_lock(&subsys->p->mutex);
1035 list_add_tail(&sif->node, &subsys->p->interfaces);
1036 if (sif->add_dev) {
1037 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1038 while ((dev = subsys_dev_iter_next(&iter)))
1039 sif->add_dev(dev, sif);
1040 subsys_dev_iter_exit(&iter);
1041 }
1042 mutex_unlock(&subsys->p->mutex);
1043
1044 return 0;
1045}
1046EXPORT_SYMBOL_GPL(subsys_interface_register);
1047
1048void subsys_interface_unregister(struct subsys_interface *sif)
1049{
1050 struct bus_type *subsys;
1051 struct subsys_dev_iter iter;
1052 struct device *dev;
1053
1054 if (!sif || !sif->subsys)
1055 return;
1056
1057 subsys = sif->subsys;
1058
1059 mutex_lock(&subsys->p->mutex);
1060 list_del_init(&sif->node);
1061 if (sif->remove_dev) {
1062 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1063 while ((dev = subsys_dev_iter_next(&iter)))
1064 sif->remove_dev(dev, sif);
1065 subsys_dev_iter_exit(&iter);
1066 }
1067 mutex_unlock(&subsys->p->mutex);
1068
1069 bus_put(subsys);
1070}
1071EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1072
1073static void system_root_device_release(struct device *dev)
1074{
1075 kfree(dev);
1076}
1077
1078static int subsys_register(struct bus_type *subsys,
1079 const struct attribute_group **groups,
1080 struct kobject *parent_of_root)
1081{
1082 struct device *dev;
1083 int err;
1084
1085 err = bus_register(subsys);
1086 if (err < 0)
1087 return err;
1088
1089 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1090 if (!dev) {
1091 err = -ENOMEM;
1092 goto err_dev;
1093 }
1094
1095 err = dev_set_name(dev, "%s", subsys->name);
1096 if (err < 0)
1097 goto err_name;
1098
1099 dev->kobj.parent = parent_of_root;
1100 dev->groups = groups;
1101 dev->release = system_root_device_release;
1102
1103 err = device_register(dev);
1104 if (err < 0)
1105 goto err_dev_reg;
1106
1107 subsys->dev_root = dev;
1108 return 0;
1109
1110err_dev_reg:
1111 put_device(dev);
1112 dev = NULL;
1113err_name:
1114 kfree(dev);
1115err_dev:
1116 bus_unregister(subsys);
1117 return err;
1118}
1119
1120/**
1121 * subsys_system_register - register a subsystem at /sys/devices/system/
1122 * @subsys: system subsystem
1123 * @groups: default attributes for the root device
1124 *
1125 * All 'system' subsystems have a /sys/devices/system/<name> root device
1126 * with the name of the subsystem. The root device can carry subsystem-
1127 * wide attributes. All registered devices are below this single root
1128 * device and are named after the subsystem with a simple enumeration
1129 * number appended. The registered devices are not explicitly named;
1130 * only 'id' in the device needs to be set.
1131 *
1132 * Do not use this interface for anything new, it exists for compatibility
1133 * with bad ideas only. New subsystems should use plain subsystems; and
1134 * add the subsystem-wide attributes should be added to the subsystem
1135 * directory itself and not some create fake root-device placed in
1136 * /sys/devices/system/<name>.
1137 */
1138int subsys_system_register(struct bus_type *subsys,
1139 const struct attribute_group **groups)
1140{
1141 return subsys_register(subsys, groups, &system_kset->kobj);
1142}
1143EXPORT_SYMBOL_GPL(subsys_system_register);
1144
1145/**
1146 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1147 * @subsys: virtual subsystem
1148 * @groups: default attributes for the root device
1149 *
1150 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1151 * with the name of the subystem. The root device can carry subsystem-wide
1152 * attributes. All registered devices are below this single root device.
1153 * There's no restriction on device naming. This is for kernel software
1154 * constructs which need sysfs interface.
1155 */
1156int subsys_virtual_register(struct bus_type *subsys,
1157 const struct attribute_group **groups)
1158{
1159 struct kobject *virtual_dir;
1160
1161 virtual_dir = virtual_device_parent(NULL);
1162 if (!virtual_dir)
1163 return -ENOMEM;
1164
1165 return subsys_register(subsys, groups, virtual_dir);
1166}
1167EXPORT_SYMBOL_GPL(subsys_virtual_register);
1168
1169int __init buses_init(void)
1170{
1171 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1172 if (!bus_kset)
1173 return -ENOMEM;
1174
1175 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1176 if (!system_kset)
1177 return -ENOMEM;
1178
1179 return 0;
1180}
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 */
24static 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
35static int __must_check bus_rescan_devices_helper(struct device *dev,
36 void *data);
37
38static 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
47static void bus_put(struct bus_type *bus)
48{
49 if (bus)
50 kset_put(&bus->p->subsys);
51}
52
53static 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
65static 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
77static const struct sysfs_ops driver_sysfs_ops = {
78 .show = drv_attr_show,
79 .store = drv_attr_store,
80};
81
82static 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
90static struct kobj_type driver_ktype = {
91 .sysfs_ops = &driver_sysfs_ops,
92 .release = driver_release,
93};
94
95/*
96 * sysfs bindings for buses
97 */
98static 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
110static 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
122static const struct sysfs_ops bus_sysfs_ops = {
123 .show = bus_attr_show,
124 .store = bus_attr_store,
125};
126
127int 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}
137EXPORT_SYMBOL_GPL(bus_create_file);
138
139void 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}
146EXPORT_SYMBOL_GPL(bus_remove_file);
147
148static void bus_release(struct kobject *kobj)
149{
150 struct subsys_private *priv = to_subsys_private(kobj);
151 struct bus_type *bus = priv->bus;
152
153 kfree(priv);
154 bus->p = NULL;
155}
156
157static struct kobj_type bus_ktype = {
158 .sysfs_ops = &bus_sysfs_ops,
159 .release = bus_release,
160};
161
162static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
163{
164 struct kobj_type *ktype = get_ktype(kobj);
165
166 if (ktype == &bus_ktype)
167 return 1;
168 return 0;
169}
170
171static const struct kset_uevent_ops bus_uevent_ops = {
172 .filter = bus_uevent_filter,
173};
174
175static struct kset *bus_kset;
176
177/* Manually detach a device from its associated driver. */
178static ssize_t unbind_store(struct device_driver *drv, const char *buf,
179 size_t count)
180{
181 struct bus_type *bus = bus_get(drv->bus);
182 struct device *dev;
183 int err = -ENODEV;
184
185 dev = bus_find_device_by_name(bus, NULL, buf);
186 if (dev && dev->driver == drv) {
187 if (dev->parent) /* Needed for USB */
188 device_lock(dev->parent);
189 device_release_driver(dev);
190 if (dev->parent)
191 device_unlock(dev->parent);
192 err = count;
193 }
194 put_device(dev);
195 bus_put(bus);
196 return err;
197}
198static DRIVER_ATTR_WO(unbind);
199
200/*
201 * Manually attach a device to a driver.
202 * Note: the driver must want to bind to the device,
203 * it is not possible to override the driver's id table.
204 */
205static ssize_t bind_store(struct device_driver *drv, const char *buf,
206 size_t count)
207{
208 struct bus_type *bus = bus_get(drv->bus);
209 struct device *dev;
210 int err = -ENODEV;
211
212 dev = bus_find_device_by_name(bus, NULL, buf);
213 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
214 if (dev->parent) /* Needed for USB */
215 device_lock(dev->parent);
216 device_lock(dev);
217 err = driver_probe_device(drv, dev);
218 device_unlock(dev);
219 if (dev->parent)
220 device_unlock(dev->parent);
221
222 if (err > 0) {
223 /* success */
224 err = count;
225 } else if (err == 0) {
226 /* driver didn't accept device */
227 err = -ENODEV;
228 }
229 }
230 put_device(dev);
231 bus_put(bus);
232 return err;
233}
234static DRIVER_ATTR_WO(bind);
235
236static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
237{
238 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
239}
240
241static ssize_t store_drivers_autoprobe(struct bus_type *bus,
242 const char *buf, size_t count)
243{
244 if (buf[0] == '0')
245 bus->p->drivers_autoprobe = 0;
246 else
247 bus->p->drivers_autoprobe = 1;
248 return count;
249}
250
251static ssize_t store_drivers_probe(struct bus_type *bus,
252 const char *buf, size_t count)
253{
254 struct device *dev;
255 int err = -EINVAL;
256
257 dev = bus_find_device_by_name(bus, NULL, buf);
258 if (!dev)
259 return -ENODEV;
260 if (bus_rescan_devices_helper(dev, NULL) == 0)
261 err = count;
262 put_device(dev);
263 return err;
264}
265
266static struct device *next_device(struct klist_iter *i)
267{
268 struct klist_node *n = klist_next(i);
269 struct device *dev = NULL;
270 struct device_private *dev_prv;
271
272 if (n) {
273 dev_prv = to_device_private_bus(n);
274 dev = dev_prv->device;
275 }
276 return dev;
277}
278
279/**
280 * bus_for_each_dev - device iterator.
281 * @bus: bus type.
282 * @start: device to start iterating from.
283 * @data: data for the callback.
284 * @fn: function to be called for each device.
285 *
286 * Iterate over @bus's list of devices, and call @fn for each,
287 * passing it @data. If @start is not NULL, we use that device to
288 * begin iterating from.
289 *
290 * We check the return of @fn each time. If it returns anything
291 * other than 0, we break out and return that value.
292 *
293 * NOTE: The device that returns a non-zero value is not retained
294 * in any way, nor is its refcount incremented. If the caller needs
295 * to retain this data, it should do so, and increment the reference
296 * count in the supplied callback.
297 */
298int bus_for_each_dev(struct bus_type *bus, struct device *start,
299 void *data, int (*fn)(struct device *, void *))
300{
301 struct klist_iter i;
302 struct device *dev;
303 int error = 0;
304
305 if (!bus || !bus->p)
306 return -EINVAL;
307
308 klist_iter_init_node(&bus->p->klist_devices, &i,
309 (start ? &start->p->knode_bus : NULL));
310 while (!error && (dev = next_device(&i)))
311 error = fn(dev, data);
312 klist_iter_exit(&i);
313 return error;
314}
315EXPORT_SYMBOL_GPL(bus_for_each_dev);
316
317/**
318 * bus_find_device - device iterator for locating a particular device.
319 * @bus: bus type
320 * @start: Device to begin with
321 * @data: Data to pass to match function
322 * @match: Callback function to check device
323 *
324 * This is similar to the bus_for_each_dev() function above, but it
325 * returns a reference to a device that is 'found' for later use, as
326 * determined by the @match callback.
327 *
328 * The callback should return 0 if the device doesn't match and non-zero
329 * if it does. If the callback returns non-zero, this function will
330 * return to the caller and not iterate over any more devices.
331 */
332struct device *bus_find_device(struct bus_type *bus,
333 struct device *start, void *data,
334 int (*match)(struct device *dev, void *data))
335{
336 struct klist_iter i;
337 struct device *dev;
338
339 if (!bus || !bus->p)
340 return NULL;
341
342 klist_iter_init_node(&bus->p->klist_devices, &i,
343 (start ? &start->p->knode_bus : NULL));
344 while ((dev = next_device(&i)))
345 if (match(dev, data) && get_device(dev))
346 break;
347 klist_iter_exit(&i);
348 return dev;
349}
350EXPORT_SYMBOL_GPL(bus_find_device);
351
352static int match_name(struct device *dev, void *data)
353{
354 const char *name = data;
355
356 return sysfs_streq(name, dev_name(dev));
357}
358
359/**
360 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
361 * @bus: bus type
362 * @start: Device to begin with
363 * @name: name of the device to match
364 *
365 * This is similar to the bus_find_device() function above, but it handles
366 * searching by a name automatically, no need to write another strcmp matching
367 * function.
368 */
369struct device *bus_find_device_by_name(struct bus_type *bus,
370 struct device *start, const char *name)
371{
372 return bus_find_device(bus, start, (void *)name, match_name);
373}
374EXPORT_SYMBOL_GPL(bus_find_device_by_name);
375
376/**
377 * subsys_find_device_by_id - find a device with a specific enumeration number
378 * @subsys: subsystem
379 * @id: index 'id' in struct device
380 * @hint: device to check first
381 *
382 * Check the hint's next object and if it is a match return it directly,
383 * otherwise, fall back to a full list search. Either way a reference for
384 * the returned object is taken.
385 */
386struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
387 struct device *hint)
388{
389 struct klist_iter i;
390 struct device *dev;
391
392 if (!subsys)
393 return NULL;
394
395 if (hint) {
396 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
397 dev = next_device(&i);
398 if (dev && dev->id == id && get_device(dev)) {
399 klist_iter_exit(&i);
400 return dev;
401 }
402 klist_iter_exit(&i);
403 }
404
405 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
406 while ((dev = next_device(&i))) {
407 if (dev->id == id && get_device(dev)) {
408 klist_iter_exit(&i);
409 return dev;
410 }
411 }
412 klist_iter_exit(&i);
413 return NULL;
414}
415EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
416
417static struct device_driver *next_driver(struct klist_iter *i)
418{
419 struct klist_node *n = klist_next(i);
420 struct driver_private *drv_priv;
421
422 if (n) {
423 drv_priv = container_of(n, struct driver_private, knode_bus);
424 return drv_priv->driver;
425 }
426 return NULL;
427}
428
429/**
430 * bus_for_each_drv - driver iterator
431 * @bus: bus we're dealing with.
432 * @start: driver to start iterating on.
433 * @data: data to pass to the callback.
434 * @fn: function to call for each driver.
435 *
436 * This is nearly identical to the device iterator above.
437 * We iterate over each driver that belongs to @bus, and call
438 * @fn for each. If @fn returns anything but 0, we break out
439 * and return it. If @start is not NULL, we use it as the head
440 * of the list.
441 *
442 * NOTE: we don't return the driver that returns a non-zero
443 * value, nor do we leave the reference count incremented for that
444 * driver. If the caller needs to know that info, it must set it
445 * in the callback. It must also be sure to increment the refcount
446 * so it doesn't disappear before returning to the caller.
447 */
448int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
449 void *data, int (*fn)(struct device_driver *, void *))
450{
451 struct klist_iter i;
452 struct device_driver *drv;
453 int error = 0;
454
455 if (!bus)
456 return -EINVAL;
457
458 klist_iter_init_node(&bus->p->klist_drivers, &i,
459 start ? &start->p->knode_bus : NULL);
460 while ((drv = next_driver(&i)) && !error)
461 error = fn(drv, data);
462 klist_iter_exit(&i);
463 return error;
464}
465EXPORT_SYMBOL_GPL(bus_for_each_drv);
466
467/**
468 * bus_add_device - add device to bus
469 * @dev: device being added
470 *
471 * - Add device's bus attributes.
472 * - Create links to device's bus.
473 * - Add the device to its bus's list of devices.
474 */
475int bus_add_device(struct device *dev)
476{
477 struct bus_type *bus = bus_get(dev->bus);
478 int error = 0;
479
480 if (bus) {
481 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
482 error = device_add_groups(dev, bus->dev_groups);
483 if (error)
484 goto out_put;
485 error = sysfs_create_link(&bus->p->devices_kset->kobj,
486 &dev->kobj, dev_name(dev));
487 if (error)
488 goto out_groups;
489 error = sysfs_create_link(&dev->kobj,
490 &dev->bus->p->subsys.kobj, "subsystem");
491 if (error)
492 goto out_subsys;
493 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
494 }
495 return 0;
496
497out_subsys:
498 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
499out_groups:
500 device_remove_groups(dev, bus->dev_groups);
501out_put:
502 bus_put(dev->bus);
503 return error;
504}
505
506/**
507 * bus_probe_device - probe drivers for a new device
508 * @dev: device to probe
509 *
510 * - Automatically probe for a driver if the bus allows it.
511 */
512void bus_probe_device(struct device *dev)
513{
514 struct bus_type *bus = dev->bus;
515 struct subsys_interface *sif;
516
517 if (!bus)
518 return;
519
520 if (bus->p->drivers_autoprobe)
521 device_initial_probe(dev);
522
523 mutex_lock(&bus->p->mutex);
524 list_for_each_entry(sif, &bus->p->interfaces, node)
525 if (sif->add_dev)
526 sif->add_dev(dev, sif);
527 mutex_unlock(&bus->p->mutex);
528}
529
530/**
531 * bus_remove_device - remove device from bus
532 * @dev: device to be removed
533 *
534 * - Remove device from all interfaces.
535 * - Remove symlink from bus' directory.
536 * - Delete device from bus's list.
537 * - Detach from its driver.
538 * - Drop reference taken in bus_add_device().
539 */
540void bus_remove_device(struct device *dev)
541{
542 struct bus_type *bus = dev->bus;
543 struct subsys_interface *sif;
544
545 if (!bus)
546 return;
547
548 mutex_lock(&bus->p->mutex);
549 list_for_each_entry(sif, &bus->p->interfaces, node)
550 if (sif->remove_dev)
551 sif->remove_dev(dev, sif);
552 mutex_unlock(&bus->p->mutex);
553
554 sysfs_remove_link(&dev->kobj, "subsystem");
555 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
556 dev_name(dev));
557 device_remove_groups(dev, dev->bus->dev_groups);
558 if (klist_node_attached(&dev->p->knode_bus))
559 klist_del(&dev->p->knode_bus);
560
561 pr_debug("bus: '%s': remove device %s\n",
562 dev->bus->name, dev_name(dev));
563 device_release_driver(dev);
564 bus_put(dev->bus);
565}
566
567static int __must_check add_bind_files(struct device_driver *drv)
568{
569 int ret;
570
571 ret = driver_create_file(drv, &driver_attr_unbind);
572 if (ret == 0) {
573 ret = driver_create_file(drv, &driver_attr_bind);
574 if (ret)
575 driver_remove_file(drv, &driver_attr_unbind);
576 }
577 return ret;
578}
579
580static void remove_bind_files(struct device_driver *drv)
581{
582 driver_remove_file(drv, &driver_attr_bind);
583 driver_remove_file(drv, &driver_attr_unbind);
584}
585
586static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
587static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
588 show_drivers_autoprobe, store_drivers_autoprobe);
589
590static int add_probe_files(struct bus_type *bus)
591{
592 int retval;
593
594 retval = bus_create_file(bus, &bus_attr_drivers_probe);
595 if (retval)
596 goto out;
597
598 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
599 if (retval)
600 bus_remove_file(bus, &bus_attr_drivers_probe);
601out:
602 return retval;
603}
604
605static void remove_probe_files(struct bus_type *bus)
606{
607 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
608 bus_remove_file(bus, &bus_attr_drivers_probe);
609}
610
611static ssize_t uevent_store(struct device_driver *drv, const char *buf,
612 size_t count)
613{
614 kobject_synth_uevent(&drv->p->kobj, buf, count);
615 return count;
616}
617static DRIVER_ATTR_WO(uevent);
618
619static void driver_attach_async(void *_drv, async_cookie_t cookie)
620{
621 struct device_driver *drv = _drv;
622 int ret;
623
624 ret = driver_attach(drv);
625
626 pr_debug("bus: '%s': driver %s async attach completed: %d\n",
627 drv->bus->name, drv->name, ret);
628}
629
630/**
631 * bus_add_driver - Add a driver to the bus.
632 * @drv: driver.
633 */
634int bus_add_driver(struct device_driver *drv)
635{
636 struct bus_type *bus;
637 struct driver_private *priv;
638 int error = 0;
639
640 bus = bus_get(drv->bus);
641 if (!bus)
642 return -EINVAL;
643
644 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
645
646 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
647 if (!priv) {
648 error = -ENOMEM;
649 goto out_put_bus;
650 }
651 klist_init(&priv->klist_devices, NULL, NULL);
652 priv->driver = drv;
653 drv->p = priv;
654 priv->kobj.kset = bus->p->drivers_kset;
655 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
656 "%s", drv->name);
657 if (error)
658 goto out_unregister;
659
660 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
661 if (drv->bus->p->drivers_autoprobe) {
662 if (driver_allows_async_probing(drv)) {
663 pr_debug("bus: '%s': probing driver %s asynchronously\n",
664 drv->bus->name, drv->name);
665 async_schedule(driver_attach_async, drv);
666 } else {
667 error = driver_attach(drv);
668 if (error)
669 goto out_unregister;
670 }
671 }
672 module_add_driver(drv->owner, drv);
673
674 error = driver_create_file(drv, &driver_attr_uevent);
675 if (error) {
676 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
677 __func__, drv->name);
678 }
679 error = driver_add_groups(drv, bus->drv_groups);
680 if (error) {
681 /* How the hell do we get out of this pickle? Give up */
682 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
683 __func__, drv->name);
684 }
685
686 if (!drv->suppress_bind_attrs) {
687 error = add_bind_files(drv);
688 if (error) {
689 /* Ditto */
690 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
691 __func__, drv->name);
692 }
693 }
694
695 return 0;
696
697out_unregister:
698 kobject_put(&priv->kobj);
699 /* drv->p is freed in driver_release() */
700 drv->p = NULL;
701out_put_bus:
702 bus_put(bus);
703 return error;
704}
705
706/**
707 * bus_remove_driver - delete driver from bus's knowledge.
708 * @drv: driver.
709 *
710 * Detach the driver from the devices it controls, and remove
711 * it from its bus's list of drivers. Finally, we drop the reference
712 * to the bus we took in bus_add_driver().
713 */
714void bus_remove_driver(struct device_driver *drv)
715{
716 if (!drv->bus)
717 return;
718
719 if (!drv->suppress_bind_attrs)
720 remove_bind_files(drv);
721 driver_remove_groups(drv, drv->bus->drv_groups);
722 driver_remove_file(drv, &driver_attr_uevent);
723 klist_remove(&drv->p->knode_bus);
724 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
725 driver_detach(drv);
726 module_remove_driver(drv);
727 kobject_put(&drv->p->kobj);
728 bus_put(drv->bus);
729}
730
731/* Helper for bus_rescan_devices's iter */
732static int __must_check bus_rescan_devices_helper(struct device *dev,
733 void *data)
734{
735 int ret = 0;
736
737 if (!dev->driver) {
738 if (dev->parent) /* Needed for USB */
739 device_lock(dev->parent);
740 ret = device_attach(dev);
741 if (dev->parent)
742 device_unlock(dev->parent);
743 }
744 return ret < 0 ? ret : 0;
745}
746
747/**
748 * bus_rescan_devices - rescan devices on the bus for possible drivers
749 * @bus: the bus to scan.
750 *
751 * This function will look for devices on the bus with no driver
752 * attached and rescan it against existing drivers to see if it matches
753 * any by calling device_attach() for the unbound devices.
754 */
755int bus_rescan_devices(struct bus_type *bus)
756{
757 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
758}
759EXPORT_SYMBOL_GPL(bus_rescan_devices);
760
761/**
762 * device_reprobe - remove driver for a device and probe for a new driver
763 * @dev: the device to reprobe
764 *
765 * This function detaches the attached driver (if any) for the given
766 * device and restarts the driver probing process. It is intended
767 * to use if probing criteria changed during a devices lifetime and
768 * driver attachment should change accordingly.
769 */
770int device_reprobe(struct device *dev)
771{
772 if (dev->driver) {
773 if (dev->parent) /* Needed for USB */
774 device_lock(dev->parent);
775 device_release_driver(dev);
776 if (dev->parent)
777 device_unlock(dev->parent);
778 }
779 return bus_rescan_devices_helper(dev, NULL);
780}
781EXPORT_SYMBOL_GPL(device_reprobe);
782
783/**
784 * find_bus - locate bus by name.
785 * @name: name of bus.
786 *
787 * Call kset_find_obj() to iterate over list of buses to
788 * find a bus by name. Return bus if found.
789 *
790 * Note that kset_find_obj increments bus' reference count.
791 */
792#if 0
793struct bus_type *find_bus(char *name)
794{
795 struct kobject *k = kset_find_obj(bus_kset, name);
796 return k ? to_bus(k) : NULL;
797}
798#endif /* 0 */
799
800static int bus_add_groups(struct bus_type *bus,
801 const struct attribute_group **groups)
802{
803 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
804}
805
806static void bus_remove_groups(struct bus_type *bus,
807 const struct attribute_group **groups)
808{
809 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
810}
811
812static void klist_devices_get(struct klist_node *n)
813{
814 struct device_private *dev_prv = to_device_private_bus(n);
815 struct device *dev = dev_prv->device;
816
817 get_device(dev);
818}
819
820static void klist_devices_put(struct klist_node *n)
821{
822 struct device_private *dev_prv = to_device_private_bus(n);
823 struct device *dev = dev_prv->device;
824
825 put_device(dev);
826}
827
828static ssize_t bus_uevent_store(struct bus_type *bus,
829 const char *buf, size_t count)
830{
831 kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
832 return count;
833}
834static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
835
836/**
837 * bus_register - register a driver-core subsystem
838 * @bus: bus to register
839 *
840 * Once we have that, we register the bus with the kobject
841 * infrastructure, then register the children subsystems it has:
842 * the devices and drivers that belong to the subsystem.
843 */
844int bus_register(struct bus_type *bus)
845{
846 int retval;
847 struct subsys_private *priv;
848 struct lock_class_key *key = &bus->lock_key;
849
850 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
851 if (!priv)
852 return -ENOMEM;
853
854 priv->bus = bus;
855 bus->p = priv;
856
857 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
858
859 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
860 if (retval)
861 goto out;
862
863 priv->subsys.kobj.kset = bus_kset;
864 priv->subsys.kobj.ktype = &bus_ktype;
865 priv->drivers_autoprobe = 1;
866
867 retval = kset_register(&priv->subsys);
868 if (retval)
869 goto out;
870
871 retval = bus_create_file(bus, &bus_attr_uevent);
872 if (retval)
873 goto bus_uevent_fail;
874
875 priv->devices_kset = kset_create_and_add("devices", NULL,
876 &priv->subsys.kobj);
877 if (!priv->devices_kset) {
878 retval = -ENOMEM;
879 goto bus_devices_fail;
880 }
881
882 priv->drivers_kset = kset_create_and_add("drivers", NULL,
883 &priv->subsys.kobj);
884 if (!priv->drivers_kset) {
885 retval = -ENOMEM;
886 goto bus_drivers_fail;
887 }
888
889 INIT_LIST_HEAD(&priv->interfaces);
890 __mutex_init(&priv->mutex, "subsys mutex", key);
891 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
892 klist_init(&priv->klist_drivers, NULL, NULL);
893
894 retval = add_probe_files(bus);
895 if (retval)
896 goto bus_probe_files_fail;
897
898 retval = bus_add_groups(bus, bus->bus_groups);
899 if (retval)
900 goto bus_groups_fail;
901
902 pr_debug("bus: '%s': registered\n", bus->name);
903 return 0;
904
905bus_groups_fail:
906 remove_probe_files(bus);
907bus_probe_files_fail:
908 kset_unregister(bus->p->drivers_kset);
909bus_drivers_fail:
910 kset_unregister(bus->p->devices_kset);
911bus_devices_fail:
912 bus_remove_file(bus, &bus_attr_uevent);
913bus_uevent_fail:
914 kset_unregister(&bus->p->subsys);
915out:
916 kfree(bus->p);
917 bus->p = NULL;
918 return retval;
919}
920EXPORT_SYMBOL_GPL(bus_register);
921
922/**
923 * bus_unregister - remove a bus from the system
924 * @bus: bus.
925 *
926 * Unregister the child subsystems and the bus itself.
927 * Finally, we call bus_put() to release the refcount
928 */
929void bus_unregister(struct bus_type *bus)
930{
931 pr_debug("bus: '%s': unregistering\n", bus->name);
932 if (bus->dev_root)
933 device_unregister(bus->dev_root);
934 bus_remove_groups(bus, bus->bus_groups);
935 remove_probe_files(bus);
936 kset_unregister(bus->p->drivers_kset);
937 kset_unregister(bus->p->devices_kset);
938 bus_remove_file(bus, &bus_attr_uevent);
939 kset_unregister(&bus->p->subsys);
940}
941EXPORT_SYMBOL_GPL(bus_unregister);
942
943int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
944{
945 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
946}
947EXPORT_SYMBOL_GPL(bus_register_notifier);
948
949int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
950{
951 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
952}
953EXPORT_SYMBOL_GPL(bus_unregister_notifier);
954
955struct kset *bus_get_kset(struct bus_type *bus)
956{
957 return &bus->p->subsys;
958}
959EXPORT_SYMBOL_GPL(bus_get_kset);
960
961struct klist *bus_get_device_klist(struct bus_type *bus)
962{
963 return &bus->p->klist_devices;
964}
965EXPORT_SYMBOL_GPL(bus_get_device_klist);
966
967/*
968 * Yes, this forcibly breaks the klist abstraction temporarily. It
969 * just wants to sort the klist, not change reference counts and
970 * take/drop locks rapidly in the process. It does all this while
971 * holding the lock for the list, so objects can't otherwise be
972 * added/removed while we're swizzling.
973 */
974static void device_insertion_sort_klist(struct device *a, struct list_head *list,
975 int (*compare)(const struct device *a,
976 const struct device *b))
977{
978 struct klist_node *n;
979 struct device_private *dev_prv;
980 struct device *b;
981
982 list_for_each_entry(n, list, n_node) {
983 dev_prv = to_device_private_bus(n);
984 b = dev_prv->device;
985 if (compare(a, b) <= 0) {
986 list_move_tail(&a->p->knode_bus.n_node,
987 &b->p->knode_bus.n_node);
988 return;
989 }
990 }
991 list_move_tail(&a->p->knode_bus.n_node, list);
992}
993
994void bus_sort_breadthfirst(struct bus_type *bus,
995 int (*compare)(const struct device *a,
996 const struct device *b))
997{
998 LIST_HEAD(sorted_devices);
999 struct klist_node *n, *tmp;
1000 struct device_private *dev_prv;
1001 struct device *dev;
1002 struct klist *device_klist;
1003
1004 device_klist = bus_get_device_klist(bus);
1005
1006 spin_lock(&device_klist->k_lock);
1007 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1008 dev_prv = to_device_private_bus(n);
1009 dev = dev_prv->device;
1010 device_insertion_sort_klist(dev, &sorted_devices, compare);
1011 }
1012 list_splice(&sorted_devices, &device_klist->k_list);
1013 spin_unlock(&device_klist->k_lock);
1014}
1015EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1016
1017/**
1018 * subsys_dev_iter_init - initialize subsys device iterator
1019 * @iter: subsys iterator to initialize
1020 * @subsys: the subsys we wanna iterate over
1021 * @start: the device to start iterating from, if any
1022 * @type: device_type of the devices to iterate over, NULL for all
1023 *
1024 * Initialize subsys iterator @iter such that it iterates over devices
1025 * of @subsys. If @start is set, the list iteration will start there,
1026 * otherwise if it is NULL, the iteration starts at the beginning of
1027 * the list.
1028 */
1029void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1030 struct device *start, const struct device_type *type)
1031{
1032 struct klist_node *start_knode = NULL;
1033
1034 if (start)
1035 start_knode = &start->p->knode_bus;
1036 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1037 iter->type = type;
1038}
1039EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1040
1041/**
1042 * subsys_dev_iter_next - iterate to the next device
1043 * @iter: subsys iterator to proceed
1044 *
1045 * Proceed @iter to the next device and return it. Returns NULL if
1046 * iteration is complete.
1047 *
1048 * The returned device is referenced and won't be released till
1049 * iterator is proceed to the next device or exited. The caller is
1050 * free to do whatever it wants to do with the device including
1051 * calling back into subsys code.
1052 */
1053struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1054{
1055 struct klist_node *knode;
1056 struct device *dev;
1057
1058 for (;;) {
1059 knode = klist_next(&iter->ki);
1060 if (!knode)
1061 return NULL;
1062 dev = to_device_private_bus(knode)->device;
1063 if (!iter->type || iter->type == dev->type)
1064 return dev;
1065 }
1066}
1067EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1068
1069/**
1070 * subsys_dev_iter_exit - finish iteration
1071 * @iter: subsys iterator to finish
1072 *
1073 * Finish an iteration. Always call this function after iteration is
1074 * complete whether the iteration ran till the end or not.
1075 */
1076void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1077{
1078 klist_iter_exit(&iter->ki);
1079}
1080EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1081
1082int subsys_interface_register(struct subsys_interface *sif)
1083{
1084 struct bus_type *subsys;
1085 struct subsys_dev_iter iter;
1086 struct device *dev;
1087
1088 if (!sif || !sif->subsys)
1089 return -ENODEV;
1090
1091 subsys = bus_get(sif->subsys);
1092 if (!subsys)
1093 return -EINVAL;
1094
1095 mutex_lock(&subsys->p->mutex);
1096 list_add_tail(&sif->node, &subsys->p->interfaces);
1097 if (sif->add_dev) {
1098 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1099 while ((dev = subsys_dev_iter_next(&iter)))
1100 sif->add_dev(dev, sif);
1101 subsys_dev_iter_exit(&iter);
1102 }
1103 mutex_unlock(&subsys->p->mutex);
1104
1105 return 0;
1106}
1107EXPORT_SYMBOL_GPL(subsys_interface_register);
1108
1109void subsys_interface_unregister(struct subsys_interface *sif)
1110{
1111 struct bus_type *subsys;
1112 struct subsys_dev_iter iter;
1113 struct device *dev;
1114
1115 if (!sif || !sif->subsys)
1116 return;
1117
1118 subsys = sif->subsys;
1119
1120 mutex_lock(&subsys->p->mutex);
1121 list_del_init(&sif->node);
1122 if (sif->remove_dev) {
1123 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1124 while ((dev = subsys_dev_iter_next(&iter)))
1125 sif->remove_dev(dev, sif);
1126 subsys_dev_iter_exit(&iter);
1127 }
1128 mutex_unlock(&subsys->p->mutex);
1129
1130 bus_put(subsys);
1131}
1132EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1133
1134static void system_root_device_release(struct device *dev)
1135{
1136 kfree(dev);
1137}
1138
1139static int subsys_register(struct bus_type *subsys,
1140 const struct attribute_group **groups,
1141 struct kobject *parent_of_root)
1142{
1143 struct device *dev;
1144 int err;
1145
1146 err = bus_register(subsys);
1147 if (err < 0)
1148 return err;
1149
1150 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1151 if (!dev) {
1152 err = -ENOMEM;
1153 goto err_dev;
1154 }
1155
1156 err = dev_set_name(dev, "%s", subsys->name);
1157 if (err < 0)
1158 goto err_name;
1159
1160 dev->kobj.parent = parent_of_root;
1161 dev->groups = groups;
1162 dev->release = system_root_device_release;
1163
1164 err = device_register(dev);
1165 if (err < 0)
1166 goto err_dev_reg;
1167
1168 subsys->dev_root = dev;
1169 return 0;
1170
1171err_dev_reg:
1172 put_device(dev);
1173 dev = NULL;
1174err_name:
1175 kfree(dev);
1176err_dev:
1177 bus_unregister(subsys);
1178 return err;
1179}
1180
1181/**
1182 * subsys_system_register - register a subsystem at /sys/devices/system/
1183 * @subsys: system subsystem
1184 * @groups: default attributes for the root device
1185 *
1186 * All 'system' subsystems have a /sys/devices/system/<name> root device
1187 * with the name of the subsystem. The root device can carry subsystem-
1188 * wide attributes. All registered devices are below this single root
1189 * device and are named after the subsystem with a simple enumeration
1190 * number appended. The registered devices are not explicitly named;
1191 * only 'id' in the device needs to be set.
1192 *
1193 * Do not use this interface for anything new, it exists for compatibility
1194 * with bad ideas only. New subsystems should use plain subsystems; and
1195 * add the subsystem-wide attributes should be added to the subsystem
1196 * directory itself and not some create fake root-device placed in
1197 * /sys/devices/system/<name>.
1198 */
1199int subsys_system_register(struct bus_type *subsys,
1200 const struct attribute_group **groups)
1201{
1202 return subsys_register(subsys, groups, &system_kset->kobj);
1203}
1204EXPORT_SYMBOL_GPL(subsys_system_register);
1205
1206/**
1207 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1208 * @subsys: virtual subsystem
1209 * @groups: default attributes for the root device
1210 *
1211 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1212 * with the name of the subystem. The root device can carry subsystem-wide
1213 * attributes. All registered devices are below this single root device.
1214 * There's no restriction on device naming. This is for kernel software
1215 * constructs which need sysfs interface.
1216 */
1217int subsys_virtual_register(struct bus_type *subsys,
1218 const struct attribute_group **groups)
1219{
1220 struct kobject *virtual_dir;
1221
1222 virtual_dir = virtual_device_parent(NULL);
1223 if (!virtual_dir)
1224 return -ENOMEM;
1225
1226 return subsys_register(subsys, groups, virtual_dir);
1227}
1228EXPORT_SYMBOL_GPL(subsys_virtual_register);
1229
1230int __init buses_init(void)
1231{
1232 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1233 if (!bus_kset)
1234 return -ENOMEM;
1235
1236 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1237 if (!system_kset)
1238 return -ENOMEM;
1239
1240 return 0;
1241}