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