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