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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 * Copyright (c) 2023 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
10 */
11
12#include <linux/async.h>
13#include <linux/device/bus.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/* /sys/bus */
29static struct kset *bus_kset;
30
31#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
32
33/*
34 * sysfs bindings for drivers
35 */
36
37#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
38
39#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
40 struct driver_attribute driver_attr_##_name = \
41 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
42
43static int __must_check bus_rescan_devices_helper(struct device *dev,
44 void *data);
45
46/**
47 * bus_to_subsys - Turn a struct bus_type into a struct subsys_private
48 *
49 * @bus: pointer to the struct bus_type to look up
50 *
51 * The driver core internals needs to work on the subsys_private structure, not
52 * the external struct bus_type pointer. This function walks the list of
53 * registered busses in the system and finds the matching one and returns the
54 * internal struct subsys_private that relates to that bus.
55 *
56 * Note, the reference count of the return value is INCREMENTED if it is not
57 * NULL. A call to subsys_put() must be done when finished with the pointer in
58 * order for it to be properly freed.
59 */
60static struct subsys_private *bus_to_subsys(const struct bus_type *bus)
61{
62 struct subsys_private *sp = NULL;
63 struct kobject *kobj;
64
65 if (!bus || !bus_kset)
66 return NULL;
67
68 spin_lock(&bus_kset->list_lock);
69
70 if (list_empty(&bus_kset->list))
71 goto done;
72
73 list_for_each_entry(kobj, &bus_kset->list, entry) {
74 struct kset *kset = container_of(kobj, struct kset, kobj);
75
76 sp = container_of_const(kset, struct subsys_private, subsys);
77 if (sp->bus == bus)
78 goto done;
79 }
80 sp = NULL;
81done:
82 sp = subsys_get(sp);
83 spin_unlock(&bus_kset->list_lock);
84 return sp;
85}
86
87static const struct bus_type *bus_get(const struct bus_type *bus)
88{
89 struct subsys_private *sp = bus_to_subsys(bus);
90
91 if (sp)
92 return bus;
93 return NULL;
94}
95
96static void bus_put(const struct bus_type *bus)
97{
98 struct subsys_private *sp = bus_to_subsys(bus);
99
100 /* two puts are required as the call to bus_to_subsys incremented it again */
101 subsys_put(sp);
102 subsys_put(sp);
103}
104
105static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
106 char *buf)
107{
108 struct driver_attribute *drv_attr = to_drv_attr(attr);
109 struct driver_private *drv_priv = to_driver(kobj);
110 ssize_t ret = -EIO;
111
112 if (drv_attr->show)
113 ret = drv_attr->show(drv_priv->driver, buf);
114 return ret;
115}
116
117static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
118 const char *buf, size_t count)
119{
120 struct driver_attribute *drv_attr = to_drv_attr(attr);
121 struct driver_private *drv_priv = to_driver(kobj);
122 ssize_t ret = -EIO;
123
124 if (drv_attr->store)
125 ret = drv_attr->store(drv_priv->driver, buf, count);
126 return ret;
127}
128
129static const struct sysfs_ops driver_sysfs_ops = {
130 .show = drv_attr_show,
131 .store = drv_attr_store,
132};
133
134static void driver_release(struct kobject *kobj)
135{
136 struct driver_private *drv_priv = to_driver(kobj);
137
138 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
139 kfree(drv_priv);
140}
141
142static const struct kobj_type driver_ktype = {
143 .sysfs_ops = &driver_sysfs_ops,
144 .release = driver_release,
145};
146
147/*
148 * sysfs bindings for buses
149 */
150static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
151 char *buf)
152{
153 struct bus_attribute *bus_attr = to_bus_attr(attr);
154 struct subsys_private *subsys_priv = to_subsys_private(kobj);
155 ssize_t ret = 0;
156
157 if (bus_attr->show)
158 ret = bus_attr->show(subsys_priv->bus, buf);
159 return ret;
160}
161
162static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
163 const char *buf, size_t count)
164{
165 struct bus_attribute *bus_attr = to_bus_attr(attr);
166 struct subsys_private *subsys_priv = to_subsys_private(kobj);
167 ssize_t ret = 0;
168
169 if (bus_attr->store)
170 ret = bus_attr->store(subsys_priv->bus, buf, count);
171 return ret;
172}
173
174static const struct sysfs_ops bus_sysfs_ops = {
175 .show = bus_attr_show,
176 .store = bus_attr_store,
177};
178
179int bus_create_file(const struct bus_type *bus, struct bus_attribute *attr)
180{
181 struct subsys_private *sp = bus_to_subsys(bus);
182 int error;
183
184 if (!sp)
185 return -EINVAL;
186
187 error = sysfs_create_file(&sp->subsys.kobj, &attr->attr);
188
189 subsys_put(sp);
190 return error;
191}
192EXPORT_SYMBOL_GPL(bus_create_file);
193
194void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr)
195{
196 struct subsys_private *sp = bus_to_subsys(bus);
197
198 if (!sp)
199 return;
200
201 sysfs_remove_file(&sp->subsys.kobj, &attr->attr);
202 subsys_put(sp);
203}
204EXPORT_SYMBOL_GPL(bus_remove_file);
205
206static void bus_release(struct kobject *kobj)
207{
208 struct subsys_private *priv = to_subsys_private(kobj);
209
210 lockdep_unregister_key(&priv->lock_key);
211 kfree(priv);
212}
213
214static const struct kobj_type bus_ktype = {
215 .sysfs_ops = &bus_sysfs_ops,
216 .release = bus_release,
217};
218
219static int bus_uevent_filter(const struct kobject *kobj)
220{
221 const struct kobj_type *ktype = get_ktype(kobj);
222
223 if (ktype == &bus_ktype)
224 return 1;
225 return 0;
226}
227
228static const struct kset_uevent_ops bus_uevent_ops = {
229 .filter = bus_uevent_filter,
230};
231
232/* Manually detach a device from its associated driver. */
233static ssize_t unbind_store(struct device_driver *drv, const char *buf,
234 size_t count)
235{
236 const struct bus_type *bus = bus_get(drv->bus);
237 struct device *dev;
238 int err = -ENODEV;
239
240 dev = bus_find_device_by_name(bus, NULL, buf);
241 if (dev && dev->driver == drv) {
242 device_driver_detach(dev);
243 err = count;
244 }
245 put_device(dev);
246 bus_put(bus);
247 return err;
248}
249static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
250
251/*
252 * Manually attach a device to a driver.
253 * Note: the driver must want to bind to the device,
254 * it is not possible to override the driver's id table.
255 */
256static ssize_t bind_store(struct device_driver *drv, const char *buf,
257 size_t count)
258{
259 const struct bus_type *bus = bus_get(drv->bus);
260 struct device *dev;
261 int err = -ENODEV;
262
263 dev = bus_find_device_by_name(bus, NULL, buf);
264 if (dev && driver_match_device(drv, dev)) {
265 err = device_driver_attach(drv, dev);
266 if (!err) {
267 /* success */
268 err = count;
269 }
270 }
271 put_device(dev);
272 bus_put(bus);
273 return err;
274}
275static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
276
277static ssize_t drivers_autoprobe_show(const struct bus_type *bus, char *buf)
278{
279 struct subsys_private *sp = bus_to_subsys(bus);
280 int ret;
281
282 if (!sp)
283 return -EINVAL;
284
285 ret = sysfs_emit(buf, "%d\n", sp->drivers_autoprobe);
286 subsys_put(sp);
287 return ret;
288}
289
290static ssize_t drivers_autoprobe_store(const struct bus_type *bus,
291 const char *buf, size_t count)
292{
293 struct subsys_private *sp = bus_to_subsys(bus);
294
295 if (!sp)
296 return -EINVAL;
297
298 if (buf[0] == '0')
299 sp->drivers_autoprobe = 0;
300 else
301 sp->drivers_autoprobe = 1;
302
303 subsys_put(sp);
304 return count;
305}
306
307static ssize_t drivers_probe_store(const struct bus_type *bus,
308 const char *buf, size_t count)
309{
310 struct device *dev;
311 int err = -EINVAL;
312
313 dev = bus_find_device_by_name(bus, NULL, buf);
314 if (!dev)
315 return -ENODEV;
316 if (bus_rescan_devices_helper(dev, NULL) == 0)
317 err = count;
318 put_device(dev);
319 return err;
320}
321
322static struct device *next_device(struct klist_iter *i)
323{
324 struct klist_node *n = klist_next(i);
325 struct device *dev = NULL;
326 struct device_private *dev_prv;
327
328 if (n) {
329 dev_prv = to_device_private_bus(n);
330 dev = dev_prv->device;
331 }
332 return dev;
333}
334
335/**
336 * bus_for_each_dev - device iterator.
337 * @bus: bus type.
338 * @start: device to start iterating from.
339 * @data: data for the callback.
340 * @fn: function to be called for each device.
341 *
342 * Iterate over @bus's list of devices, and call @fn for each,
343 * passing it @data. If @start is not NULL, we use that device to
344 * begin iterating from.
345 *
346 * We check the return of @fn each time. If it returns anything
347 * other than 0, we break out and return that value.
348 *
349 * NOTE: The device that returns a non-zero value is not retained
350 * in any way, nor is its refcount incremented. If the caller needs
351 * to retain this data, it should do so, and increment the reference
352 * count in the supplied callback.
353 */
354int bus_for_each_dev(const struct bus_type *bus, struct device *start,
355 void *data, int (*fn)(struct device *, void *))
356{
357 struct subsys_private *sp = bus_to_subsys(bus);
358 struct klist_iter i;
359 struct device *dev;
360 int error = 0;
361
362 if (!sp)
363 return -EINVAL;
364
365 klist_iter_init_node(&sp->klist_devices, &i,
366 (start ? &start->p->knode_bus : NULL));
367 while (!error && (dev = next_device(&i)))
368 error = fn(dev, data);
369 klist_iter_exit(&i);
370 subsys_put(sp);
371 return error;
372}
373EXPORT_SYMBOL_GPL(bus_for_each_dev);
374
375/**
376 * bus_find_device - device iterator for locating a particular device.
377 * @bus: bus type
378 * @start: Device to begin with
379 * @data: Data to pass to match function
380 * @match: Callback function to check device
381 *
382 * This is similar to the bus_for_each_dev() function above, but it
383 * returns a reference to a device that is 'found' for later use, as
384 * determined by the @match callback.
385 *
386 * The callback should return 0 if the device doesn't match and non-zero
387 * if it does. If the callback returns non-zero, this function will
388 * return to the caller and not iterate over any more devices.
389 */
390struct device *bus_find_device(const struct bus_type *bus,
391 struct device *start, const void *data,
392 int (*match)(struct device *dev, const void *data))
393{
394 struct subsys_private *sp = bus_to_subsys(bus);
395 struct klist_iter i;
396 struct device *dev;
397
398 if (!sp)
399 return NULL;
400
401 klist_iter_init_node(&sp->klist_devices, &i,
402 (start ? &start->p->knode_bus : NULL));
403 while ((dev = next_device(&i)))
404 if (match(dev, data) && get_device(dev))
405 break;
406 klist_iter_exit(&i);
407 subsys_put(sp);
408 return dev;
409}
410EXPORT_SYMBOL_GPL(bus_find_device);
411
412static struct device_driver *next_driver(struct klist_iter *i)
413{
414 struct klist_node *n = klist_next(i);
415 struct driver_private *drv_priv;
416
417 if (n) {
418 drv_priv = container_of(n, struct driver_private, knode_bus);
419 return drv_priv->driver;
420 }
421 return NULL;
422}
423
424/**
425 * bus_for_each_drv - driver iterator
426 * @bus: bus we're dealing with.
427 * @start: driver to start iterating on.
428 * @data: data to pass to the callback.
429 * @fn: function to call for each driver.
430 *
431 * This is nearly identical to the device iterator above.
432 * We iterate over each driver that belongs to @bus, and call
433 * @fn for each. If @fn returns anything but 0, we break out
434 * and return it. If @start is not NULL, we use it as the head
435 * of the list.
436 *
437 * NOTE: we don't return the driver that returns a non-zero
438 * value, nor do we leave the reference count incremented for that
439 * driver. If the caller needs to know that info, it must set it
440 * in the callback. It must also be sure to increment the refcount
441 * so it doesn't disappear before returning to the caller.
442 */
443int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start,
444 void *data, int (*fn)(struct device_driver *, void *))
445{
446 struct subsys_private *sp = bus_to_subsys(bus);
447 struct klist_iter i;
448 struct device_driver *drv;
449 int error = 0;
450
451 if (!sp)
452 return -EINVAL;
453
454 klist_iter_init_node(&sp->klist_drivers, &i,
455 start ? &start->p->knode_bus : NULL);
456 while ((drv = next_driver(&i)) && !error)
457 error = fn(drv, data);
458 klist_iter_exit(&i);
459 subsys_put(sp);
460 return error;
461}
462EXPORT_SYMBOL_GPL(bus_for_each_drv);
463
464/**
465 * bus_add_device - add device to bus
466 * @dev: device being added
467 *
468 * - Add device's bus attributes.
469 * - Create links to device's bus.
470 * - Add the device to its bus's list of devices.
471 */
472int bus_add_device(struct device *dev)
473{
474 struct subsys_private *sp = bus_to_subsys(dev->bus);
475 int error;
476
477 if (!sp) {
478 /*
479 * This is a normal operation for many devices that do not
480 * have a bus assigned to them, just say that all went
481 * well.
482 */
483 return 0;
484 }
485
486 /*
487 * Reference in sp is now incremented and will be dropped when
488 * the device is removed from the bus
489 */
490
491 pr_debug("bus: '%s': add device %s\n", sp->bus->name, dev_name(dev));
492
493 error = device_add_groups(dev, sp->bus->dev_groups);
494 if (error)
495 goto out_put;
496
497 error = sysfs_create_link(&sp->devices_kset->kobj, &dev->kobj, dev_name(dev));
498 if (error)
499 goto out_groups;
500
501 error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
502 if (error)
503 goto out_subsys;
504
505 klist_add_tail(&dev->p->knode_bus, &sp->klist_devices);
506 return 0;
507
508out_subsys:
509 sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
510out_groups:
511 device_remove_groups(dev, sp->bus->dev_groups);
512out_put:
513 subsys_put(sp);
514 return error;
515}
516
517/**
518 * bus_probe_device - probe drivers for a new device
519 * @dev: device to probe
520 *
521 * - Automatically probe for a driver if the bus allows it.
522 */
523void bus_probe_device(struct device *dev)
524{
525 struct subsys_private *sp = bus_to_subsys(dev->bus);
526 struct subsys_interface *sif;
527
528 if (!sp)
529 return;
530
531 if (sp->drivers_autoprobe)
532 device_initial_probe(dev);
533
534 mutex_lock(&sp->mutex);
535 list_for_each_entry(sif, &sp->interfaces, node)
536 if (sif->add_dev)
537 sif->add_dev(dev, sif);
538 mutex_unlock(&sp->mutex);
539 subsys_put(sp);
540}
541
542/**
543 * bus_remove_device - remove device from bus
544 * @dev: device to be removed
545 *
546 * - Remove device from all interfaces.
547 * - Remove symlink from bus' directory.
548 * - Delete device from bus's list.
549 * - Detach from its driver.
550 * - Drop reference taken in bus_add_device().
551 */
552void bus_remove_device(struct device *dev)
553{
554 struct subsys_private *sp = bus_to_subsys(dev->bus);
555 struct subsys_interface *sif;
556
557 if (!sp)
558 return;
559
560 mutex_lock(&sp->mutex);
561 list_for_each_entry(sif, &sp->interfaces, node)
562 if (sif->remove_dev)
563 sif->remove_dev(dev, sif);
564 mutex_unlock(&sp->mutex);
565
566 sysfs_remove_link(&dev->kobj, "subsystem");
567 sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
568 device_remove_groups(dev, dev->bus->dev_groups);
569 if (klist_node_attached(&dev->p->knode_bus))
570 klist_del(&dev->p->knode_bus);
571
572 pr_debug("bus: '%s': remove device %s\n",
573 dev->bus->name, dev_name(dev));
574 device_release_driver(dev);
575
576 /*
577 * Decrement the reference count twice, once for the bus_to_subsys()
578 * call in the start of this function, and the second one from the
579 * reference increment in bus_add_device()
580 */
581 subsys_put(sp);
582 subsys_put(sp);
583}
584
585static int __must_check add_bind_files(struct device_driver *drv)
586{
587 int ret;
588
589 ret = driver_create_file(drv, &driver_attr_unbind);
590 if (ret == 0) {
591 ret = driver_create_file(drv, &driver_attr_bind);
592 if (ret)
593 driver_remove_file(drv, &driver_attr_unbind);
594 }
595 return ret;
596}
597
598static void remove_bind_files(struct device_driver *drv)
599{
600 driver_remove_file(drv, &driver_attr_bind);
601 driver_remove_file(drv, &driver_attr_unbind);
602}
603
604static BUS_ATTR_WO(drivers_probe);
605static BUS_ATTR_RW(drivers_autoprobe);
606
607static int add_probe_files(const struct bus_type *bus)
608{
609 int retval;
610
611 retval = bus_create_file(bus, &bus_attr_drivers_probe);
612 if (retval)
613 goto out;
614
615 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
616 if (retval)
617 bus_remove_file(bus, &bus_attr_drivers_probe);
618out:
619 return retval;
620}
621
622static void remove_probe_files(const struct bus_type *bus)
623{
624 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
625 bus_remove_file(bus, &bus_attr_drivers_probe);
626}
627
628static ssize_t uevent_store(struct device_driver *drv, const char *buf,
629 size_t count)
630{
631 int rc;
632
633 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
634 return rc ? rc : count;
635}
636static DRIVER_ATTR_WO(uevent);
637
638/**
639 * bus_add_driver - Add a driver to the bus.
640 * @drv: driver.
641 */
642int bus_add_driver(struct device_driver *drv)
643{
644 struct subsys_private *sp = bus_to_subsys(drv->bus);
645 struct driver_private *priv;
646 int error = 0;
647
648 if (!sp)
649 return -EINVAL;
650
651 /*
652 * Reference in sp is now incremented and will be dropped when
653 * the driver is removed from the bus
654 */
655 pr_debug("bus: '%s': add driver %s\n", sp->bus->name, drv->name);
656
657 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
658 if (!priv) {
659 error = -ENOMEM;
660 goto out_put_bus;
661 }
662 klist_init(&priv->klist_devices, NULL, NULL);
663 priv->driver = drv;
664 drv->p = priv;
665 priv->kobj.kset = sp->drivers_kset;
666 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
667 "%s", drv->name);
668 if (error)
669 goto out_unregister;
670
671 klist_add_tail(&priv->knode_bus, &sp->klist_drivers);
672 if (sp->drivers_autoprobe) {
673 error = driver_attach(drv);
674 if (error)
675 goto out_del_list;
676 }
677 error = module_add_driver(drv->owner, drv);
678 if (error) {
679 printk(KERN_ERR "%s: failed to create module links for %s\n",
680 __func__, drv->name);
681 goto out_detach;
682 }
683
684 error = driver_create_file(drv, &driver_attr_uevent);
685 if (error) {
686 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
687 __func__, drv->name);
688 }
689 error = driver_add_groups(drv, sp->bus->drv_groups);
690 if (error) {
691 /* How the hell do we get out of this pickle? Give up */
692 printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
693 __func__, drv->name);
694 }
695
696 if (!drv->suppress_bind_attrs) {
697 error = add_bind_files(drv);
698 if (error) {
699 /* Ditto */
700 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
701 __func__, drv->name);
702 }
703 }
704
705 return 0;
706
707out_detach:
708 driver_detach(drv);
709out_del_list:
710 klist_del(&priv->knode_bus);
711out_unregister:
712 kobject_put(&priv->kobj);
713 /* drv->p is freed in driver_release() */
714 drv->p = NULL;
715out_put_bus:
716 subsys_put(sp);
717 return error;
718}
719
720/**
721 * bus_remove_driver - delete driver from bus's knowledge.
722 * @drv: driver.
723 *
724 * Detach the driver from the devices it controls, and remove
725 * it from its bus's list of drivers. Finally, we drop the reference
726 * to the bus we took in bus_add_driver().
727 */
728void bus_remove_driver(struct device_driver *drv)
729{
730 struct subsys_private *sp = bus_to_subsys(drv->bus);
731
732 if (!sp)
733 return;
734
735 pr_debug("bus: '%s': remove driver %s\n", sp->bus->name, drv->name);
736
737 if (!drv->suppress_bind_attrs)
738 remove_bind_files(drv);
739 driver_remove_groups(drv, sp->bus->drv_groups);
740 driver_remove_file(drv, &driver_attr_uevent);
741 klist_remove(&drv->p->knode_bus);
742 driver_detach(drv);
743 module_remove_driver(drv);
744 kobject_put(&drv->p->kobj);
745
746 /*
747 * Decrement the reference count twice, once for the bus_to_subsys()
748 * call in the start of this function, and the second one from the
749 * reference increment in bus_add_driver()
750 */
751 subsys_put(sp);
752 subsys_put(sp);
753}
754
755/* Helper for bus_rescan_devices's iter */
756static int __must_check bus_rescan_devices_helper(struct device *dev,
757 void *data)
758{
759 int ret = 0;
760
761 if (!dev->driver) {
762 if (dev->parent && dev->bus->need_parent_lock)
763 device_lock(dev->parent);
764 ret = device_attach(dev);
765 if (dev->parent && dev->bus->need_parent_lock)
766 device_unlock(dev->parent);
767 }
768 return ret < 0 ? ret : 0;
769}
770
771/**
772 * bus_rescan_devices - rescan devices on the bus for possible drivers
773 * @bus: the bus to scan.
774 *
775 * This function will look for devices on the bus with no driver
776 * attached and rescan it against existing drivers to see if it matches
777 * any by calling device_attach() for the unbound devices.
778 */
779int bus_rescan_devices(const struct bus_type *bus)
780{
781 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
782}
783EXPORT_SYMBOL_GPL(bus_rescan_devices);
784
785/**
786 * device_reprobe - remove driver for a device and probe for a new driver
787 * @dev: the device to reprobe
788 *
789 * This function detaches the attached driver (if any) for the given
790 * device and restarts the driver probing process. It is intended
791 * to use if probing criteria changed during a devices lifetime and
792 * driver attachment should change accordingly.
793 */
794int device_reprobe(struct device *dev)
795{
796 if (dev->driver)
797 device_driver_detach(dev);
798 return bus_rescan_devices_helper(dev, NULL);
799}
800EXPORT_SYMBOL_GPL(device_reprobe);
801
802static void klist_devices_get(struct klist_node *n)
803{
804 struct device_private *dev_prv = to_device_private_bus(n);
805 struct device *dev = dev_prv->device;
806
807 get_device(dev);
808}
809
810static void klist_devices_put(struct klist_node *n)
811{
812 struct device_private *dev_prv = to_device_private_bus(n);
813 struct device *dev = dev_prv->device;
814
815 put_device(dev);
816}
817
818static ssize_t bus_uevent_store(const struct bus_type *bus,
819 const char *buf, size_t count)
820{
821 struct subsys_private *sp = bus_to_subsys(bus);
822 int ret;
823
824 if (!sp)
825 return -EINVAL;
826
827 ret = kobject_synth_uevent(&sp->subsys.kobj, buf, count);
828 subsys_put(sp);
829
830 if (ret)
831 return ret;
832 return count;
833}
834/*
835 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
836 * here, but can not use it as earlier in the file we have
837 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
838 * function name.
839 */
840static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
841 bus_uevent_store);
842
843/**
844 * bus_register - register a driver-core subsystem
845 * @bus: bus to register
846 *
847 * Once we have that, we register the bus with the kobject
848 * infrastructure, then register the children subsystems it has:
849 * the devices and drivers that belong to the subsystem.
850 */
851int bus_register(const struct bus_type *bus)
852{
853 int retval;
854 struct subsys_private *priv;
855 struct kobject *bus_kobj;
856 struct lock_class_key *key;
857
858 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
859 if (!priv)
860 return -ENOMEM;
861
862 priv->bus = bus;
863
864 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
865
866 bus_kobj = &priv->subsys.kobj;
867 retval = kobject_set_name(bus_kobj, "%s", bus->name);
868 if (retval)
869 goto out;
870
871 bus_kobj->kset = bus_kset;
872 bus_kobj->ktype = &bus_ktype;
873 priv->drivers_autoprobe = 1;
874
875 retval = kset_register(&priv->subsys);
876 if (retval)
877 goto out;
878
879 retval = bus_create_file(bus, &bus_attr_uevent);
880 if (retval)
881 goto bus_uevent_fail;
882
883 priv->devices_kset = kset_create_and_add("devices", NULL, bus_kobj);
884 if (!priv->devices_kset) {
885 retval = -ENOMEM;
886 goto bus_devices_fail;
887 }
888
889 priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj);
890 if (!priv->drivers_kset) {
891 retval = -ENOMEM;
892 goto bus_drivers_fail;
893 }
894
895 INIT_LIST_HEAD(&priv->interfaces);
896 key = &priv->lock_key;
897 lockdep_register_key(key);
898 __mutex_init(&priv->mutex, "subsys mutex", key);
899 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
900 klist_init(&priv->klist_drivers, NULL, NULL);
901
902 retval = add_probe_files(bus);
903 if (retval)
904 goto bus_probe_files_fail;
905
906 retval = sysfs_create_groups(bus_kobj, bus->bus_groups);
907 if (retval)
908 goto bus_groups_fail;
909
910 pr_debug("bus: '%s': registered\n", bus->name);
911 return 0;
912
913bus_groups_fail:
914 remove_probe_files(bus);
915bus_probe_files_fail:
916 kset_unregister(priv->drivers_kset);
917bus_drivers_fail:
918 kset_unregister(priv->devices_kset);
919bus_devices_fail:
920 bus_remove_file(bus, &bus_attr_uevent);
921bus_uevent_fail:
922 kset_unregister(&priv->subsys);
923out:
924 kfree(priv);
925 return retval;
926}
927EXPORT_SYMBOL_GPL(bus_register);
928
929/**
930 * bus_unregister - remove a bus from the system
931 * @bus: bus.
932 *
933 * Unregister the child subsystems and the bus itself.
934 * Finally, we call bus_put() to release the refcount
935 */
936void bus_unregister(const struct bus_type *bus)
937{
938 struct subsys_private *sp = bus_to_subsys(bus);
939 struct kobject *bus_kobj;
940
941 if (!sp)
942 return;
943
944 pr_debug("bus: '%s': unregistering\n", bus->name);
945 if (sp->dev_root)
946 device_unregister(sp->dev_root);
947
948 bus_kobj = &sp->subsys.kobj;
949 sysfs_remove_groups(bus_kobj, bus->bus_groups);
950 remove_probe_files(bus);
951 bus_remove_file(bus, &bus_attr_uevent);
952
953 kset_unregister(sp->drivers_kset);
954 kset_unregister(sp->devices_kset);
955 kset_unregister(&sp->subsys);
956 subsys_put(sp);
957}
958EXPORT_SYMBOL_GPL(bus_unregister);
959
960int bus_register_notifier(const struct bus_type *bus, struct notifier_block *nb)
961{
962 struct subsys_private *sp = bus_to_subsys(bus);
963 int retval;
964
965 if (!sp)
966 return -EINVAL;
967
968 retval = blocking_notifier_chain_register(&sp->bus_notifier, nb);
969 subsys_put(sp);
970 return retval;
971}
972EXPORT_SYMBOL_GPL(bus_register_notifier);
973
974int bus_unregister_notifier(const struct bus_type *bus, struct notifier_block *nb)
975{
976 struct subsys_private *sp = bus_to_subsys(bus);
977 int retval;
978
979 if (!sp)
980 return -EINVAL;
981 retval = blocking_notifier_chain_unregister(&sp->bus_notifier, nb);
982 subsys_put(sp);
983 return retval;
984}
985EXPORT_SYMBOL_GPL(bus_unregister_notifier);
986
987void bus_notify(struct device *dev, enum bus_notifier_event value)
988{
989 struct subsys_private *sp = bus_to_subsys(dev->bus);
990
991 if (!sp)
992 return;
993
994 blocking_notifier_call_chain(&sp->bus_notifier, value, dev);
995 subsys_put(sp);
996}
997
998struct kset *bus_get_kset(const struct bus_type *bus)
999{
1000 struct subsys_private *sp = bus_to_subsys(bus);
1001 struct kset *kset;
1002
1003 if (!sp)
1004 return NULL;
1005
1006 kset = &sp->subsys;
1007 subsys_put(sp);
1008
1009 return kset;
1010}
1011EXPORT_SYMBOL_GPL(bus_get_kset);
1012
1013/*
1014 * Yes, this forcibly breaks the klist abstraction temporarily. It
1015 * just wants to sort the klist, not change reference counts and
1016 * take/drop locks rapidly in the process. It does all this while
1017 * holding the lock for the list, so objects can't otherwise be
1018 * added/removed while we're swizzling.
1019 */
1020static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1021 int (*compare)(const struct device *a,
1022 const struct device *b))
1023{
1024 struct klist_node *n;
1025 struct device_private *dev_prv;
1026 struct device *b;
1027
1028 list_for_each_entry(n, list, n_node) {
1029 dev_prv = to_device_private_bus(n);
1030 b = dev_prv->device;
1031 if (compare(a, b) <= 0) {
1032 list_move_tail(&a->p->knode_bus.n_node,
1033 &b->p->knode_bus.n_node);
1034 return;
1035 }
1036 }
1037 list_move_tail(&a->p->knode_bus.n_node, list);
1038}
1039
1040void bus_sort_breadthfirst(const struct bus_type *bus,
1041 int (*compare)(const struct device *a,
1042 const struct device *b))
1043{
1044 struct subsys_private *sp = bus_to_subsys(bus);
1045 LIST_HEAD(sorted_devices);
1046 struct klist_node *n, *tmp;
1047 struct device_private *dev_prv;
1048 struct device *dev;
1049 struct klist *device_klist;
1050
1051 if (!sp)
1052 return;
1053 device_klist = &sp->klist_devices;
1054
1055 spin_lock(&device_klist->k_lock);
1056 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1057 dev_prv = to_device_private_bus(n);
1058 dev = dev_prv->device;
1059 device_insertion_sort_klist(dev, &sorted_devices, compare);
1060 }
1061 list_splice(&sorted_devices, &device_klist->k_list);
1062 spin_unlock(&device_klist->k_lock);
1063 subsys_put(sp);
1064}
1065EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1066
1067struct subsys_dev_iter {
1068 struct klist_iter ki;
1069 const struct device_type *type;
1070};
1071
1072/**
1073 * subsys_dev_iter_init - initialize subsys device iterator
1074 * @iter: subsys iterator to initialize
1075 * @sp: the subsys private (i.e. bus) we wanna iterate over
1076 * @start: the device to start iterating from, if any
1077 * @type: device_type of the devices to iterate over, NULL for all
1078 *
1079 * Initialize subsys iterator @iter such that it iterates over devices
1080 * of @subsys. If @start is set, the list iteration will start there,
1081 * otherwise if it is NULL, the iteration starts at the beginning of
1082 * the list.
1083 */
1084static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct subsys_private *sp,
1085 struct device *start, const struct device_type *type)
1086{
1087 struct klist_node *start_knode = NULL;
1088
1089 if (start)
1090 start_knode = &start->p->knode_bus;
1091 klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
1092 iter->type = type;
1093}
1094
1095/**
1096 * subsys_dev_iter_next - iterate to the next device
1097 * @iter: subsys iterator to proceed
1098 *
1099 * Proceed @iter to the next device and return it. Returns NULL if
1100 * iteration is complete.
1101 *
1102 * The returned device is referenced and won't be released till
1103 * iterator is proceed to the next device or exited. The caller is
1104 * free to do whatever it wants to do with the device including
1105 * calling back into subsys code.
1106 */
1107static struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1108{
1109 struct klist_node *knode;
1110 struct device *dev;
1111
1112 for (;;) {
1113 knode = klist_next(&iter->ki);
1114 if (!knode)
1115 return NULL;
1116 dev = to_device_private_bus(knode)->device;
1117 if (!iter->type || iter->type == dev->type)
1118 return dev;
1119 }
1120}
1121
1122/**
1123 * subsys_dev_iter_exit - finish iteration
1124 * @iter: subsys iterator to finish
1125 *
1126 * Finish an iteration. Always call this function after iteration is
1127 * complete whether the iteration ran till the end or not.
1128 */
1129static void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1130{
1131 klist_iter_exit(&iter->ki);
1132}
1133
1134int subsys_interface_register(struct subsys_interface *sif)
1135{
1136 struct subsys_private *sp;
1137 struct subsys_dev_iter iter;
1138 struct device *dev;
1139
1140 if (!sif || !sif->subsys)
1141 return -ENODEV;
1142
1143 sp = bus_to_subsys(sif->subsys);
1144 if (!sp)
1145 return -EINVAL;
1146
1147 /*
1148 * Reference in sp is now incremented and will be dropped when
1149 * the interface is removed from the bus
1150 */
1151
1152 mutex_lock(&sp->mutex);
1153 list_add_tail(&sif->node, &sp->interfaces);
1154 if (sif->add_dev) {
1155 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1156 while ((dev = subsys_dev_iter_next(&iter)))
1157 sif->add_dev(dev, sif);
1158 subsys_dev_iter_exit(&iter);
1159 }
1160 mutex_unlock(&sp->mutex);
1161
1162 return 0;
1163}
1164EXPORT_SYMBOL_GPL(subsys_interface_register);
1165
1166void subsys_interface_unregister(struct subsys_interface *sif)
1167{
1168 struct subsys_private *sp;
1169 struct subsys_dev_iter iter;
1170 struct device *dev;
1171
1172 if (!sif || !sif->subsys)
1173 return;
1174
1175 sp = bus_to_subsys(sif->subsys);
1176 if (!sp)
1177 return;
1178
1179 mutex_lock(&sp->mutex);
1180 list_del_init(&sif->node);
1181 if (sif->remove_dev) {
1182 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1183 while ((dev = subsys_dev_iter_next(&iter)))
1184 sif->remove_dev(dev, sif);
1185 subsys_dev_iter_exit(&iter);
1186 }
1187 mutex_unlock(&sp->mutex);
1188
1189 /*
1190 * Decrement the reference count twice, once for the bus_to_subsys()
1191 * call in the start of this function, and the second one from the
1192 * reference increment in subsys_interface_register()
1193 */
1194 subsys_put(sp);
1195 subsys_put(sp);
1196}
1197EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1198
1199static void system_root_device_release(struct device *dev)
1200{
1201 kfree(dev);
1202}
1203
1204static int subsys_register(const struct bus_type *subsys,
1205 const struct attribute_group **groups,
1206 struct kobject *parent_of_root)
1207{
1208 struct subsys_private *sp;
1209 struct device *dev;
1210 int err;
1211
1212 err = bus_register(subsys);
1213 if (err < 0)
1214 return err;
1215
1216 sp = bus_to_subsys(subsys);
1217 if (!sp) {
1218 err = -EINVAL;
1219 goto err_sp;
1220 }
1221
1222 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1223 if (!dev) {
1224 err = -ENOMEM;
1225 goto err_dev;
1226 }
1227
1228 err = dev_set_name(dev, "%s", subsys->name);
1229 if (err < 0)
1230 goto err_name;
1231
1232 dev->kobj.parent = parent_of_root;
1233 dev->groups = groups;
1234 dev->release = system_root_device_release;
1235
1236 err = device_register(dev);
1237 if (err < 0)
1238 goto err_dev_reg;
1239
1240 sp->dev_root = dev;
1241 subsys_put(sp);
1242 return 0;
1243
1244err_dev_reg:
1245 put_device(dev);
1246 dev = NULL;
1247err_name:
1248 kfree(dev);
1249err_dev:
1250 subsys_put(sp);
1251err_sp:
1252 bus_unregister(subsys);
1253 return err;
1254}
1255
1256/**
1257 * subsys_system_register - register a subsystem at /sys/devices/system/
1258 * @subsys: system subsystem
1259 * @groups: default attributes for the root device
1260 *
1261 * All 'system' subsystems have a /sys/devices/system/<name> root device
1262 * with the name of the subsystem. The root device can carry subsystem-
1263 * wide attributes. All registered devices are below this single root
1264 * device and are named after the subsystem with a simple enumeration
1265 * number appended. The registered devices are not explicitly named;
1266 * only 'id' in the device needs to be set.
1267 *
1268 * Do not use this interface for anything new, it exists for compatibility
1269 * with bad ideas only. New subsystems should use plain subsystems; and
1270 * add the subsystem-wide attributes should be added to the subsystem
1271 * directory itself and not some create fake root-device placed in
1272 * /sys/devices/system/<name>.
1273 */
1274int subsys_system_register(const struct bus_type *subsys,
1275 const struct attribute_group **groups)
1276{
1277 return subsys_register(subsys, groups, &system_kset->kobj);
1278}
1279EXPORT_SYMBOL_GPL(subsys_system_register);
1280
1281/**
1282 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1283 * @subsys: virtual subsystem
1284 * @groups: default attributes for the root device
1285 *
1286 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1287 * with the name of the subystem. The root device can carry subsystem-wide
1288 * attributes. All registered devices are below this single root device.
1289 * There's no restriction on device naming. This is for kernel software
1290 * constructs which need sysfs interface.
1291 */
1292int subsys_virtual_register(const struct bus_type *subsys,
1293 const struct attribute_group **groups)
1294{
1295 struct kobject *virtual_dir;
1296
1297 virtual_dir = virtual_device_parent(NULL);
1298 if (!virtual_dir)
1299 return -ENOMEM;
1300
1301 return subsys_register(subsys, groups, virtual_dir);
1302}
1303EXPORT_SYMBOL_GPL(subsys_virtual_register);
1304
1305/**
1306 * driver_find - locate driver on a bus by its name.
1307 * @name: name of the driver.
1308 * @bus: bus to scan for the driver.
1309 *
1310 * Call kset_find_obj() to iterate over list of drivers on
1311 * a bus to find driver by name. Return driver if found.
1312 *
1313 * This routine provides no locking to prevent the driver it returns
1314 * from being unregistered or unloaded while the caller is using it.
1315 * The caller is responsible for preventing this.
1316 */
1317struct device_driver *driver_find(const char *name, const struct bus_type *bus)
1318{
1319 struct subsys_private *sp = bus_to_subsys(bus);
1320 struct kobject *k;
1321 struct driver_private *priv;
1322
1323 if (!sp)
1324 return NULL;
1325
1326 k = kset_find_obj(sp->drivers_kset, name);
1327 subsys_put(sp);
1328 if (!k)
1329 return NULL;
1330
1331 priv = to_driver(k);
1332
1333 /* Drop reference added by kset_find_obj() */
1334 kobject_put(k);
1335 return priv->driver;
1336}
1337EXPORT_SYMBOL_GPL(driver_find);
1338
1339/*
1340 * Warning, the value could go to "removed" instantly after calling this function, so be very
1341 * careful when calling it...
1342 */
1343bool bus_is_registered(const struct bus_type *bus)
1344{
1345 struct subsys_private *sp = bus_to_subsys(bus);
1346 bool is_initialized = false;
1347
1348 if (sp) {
1349 is_initialized = true;
1350 subsys_put(sp);
1351 }
1352 return is_initialized;
1353}
1354
1355/**
1356 * bus_get_dev_root - return a pointer to the "device root" of a bus
1357 * @bus: bus to return the device root of.
1358 *
1359 * If a bus has a "device root" structure, return it, WITH THE REFERENCE
1360 * COUNT INCREMENTED.
1361 *
1362 * Note, when finished with the device, a call to put_device() is required.
1363 *
1364 * If the device root is not present (or bus is not a valid pointer), NULL
1365 * will be returned.
1366 */
1367struct device *bus_get_dev_root(const struct bus_type *bus)
1368{
1369 struct subsys_private *sp = bus_to_subsys(bus);
1370 struct device *dev_root;
1371
1372 if (!sp)
1373 return NULL;
1374
1375 dev_root = get_device(sp->dev_root);
1376 subsys_put(sp);
1377 return dev_root;
1378}
1379EXPORT_SYMBOL_GPL(bus_get_dev_root);
1380
1381int __init buses_init(void)
1382{
1383 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1384 if (!bus_kset)
1385 return -ENOMEM;
1386
1387 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1388 if (!system_kset)
1389 return -ENOMEM;
1390
1391 return 0;
1392}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * bus.c - bus driver management
4 *
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
8 * Copyright (c) 2007 Novell Inc.
9 */
10
11#include <linux/async.h>
12#include <linux/device.h>
13#include <linux/module.h>
14#include <linux/errno.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/string.h>
18#include <linux/mutex.h>
19#include <linux/sysfs.h>
20#include "base.h"
21#include "power/power.h"
22
23/* /sys/devices/system */
24static struct kset *system_kset;
25
26#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
27
28/*
29 * sysfs bindings for drivers
30 */
31
32#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
33
34#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
35 struct driver_attribute driver_attr_##_name = \
36 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
37
38static int __must_check bus_rescan_devices_helper(struct device *dev,
39 void *data);
40
41static struct bus_type *bus_get(struct bus_type *bus)
42{
43 if (bus) {
44 kset_get(&bus->p->subsys);
45 return bus;
46 }
47 return NULL;
48}
49
50static void bus_put(struct bus_type *bus)
51{
52 if (bus)
53 kset_put(&bus->p->subsys);
54}
55
56static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
57 char *buf)
58{
59 struct driver_attribute *drv_attr = to_drv_attr(attr);
60 struct driver_private *drv_priv = to_driver(kobj);
61 ssize_t ret = -EIO;
62
63 if (drv_attr->show)
64 ret = drv_attr->show(drv_priv->driver, buf);
65 return ret;
66}
67
68static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
69 const char *buf, size_t count)
70{
71 struct driver_attribute *drv_attr = to_drv_attr(attr);
72 struct driver_private *drv_priv = to_driver(kobj);
73 ssize_t ret = -EIO;
74
75 if (drv_attr->store)
76 ret = drv_attr->store(drv_priv->driver, buf, count);
77 return ret;
78}
79
80static const struct sysfs_ops driver_sysfs_ops = {
81 .show = drv_attr_show,
82 .store = drv_attr_store,
83};
84
85static void driver_release(struct kobject *kobj)
86{
87 struct driver_private *drv_priv = to_driver(kobj);
88
89 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
90 kfree(drv_priv);
91}
92
93static struct kobj_type driver_ktype = {
94 .sysfs_ops = &driver_sysfs_ops,
95 .release = driver_release,
96};
97
98/*
99 * sysfs bindings for buses
100 */
101static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
102 char *buf)
103{
104 struct bus_attribute *bus_attr = to_bus_attr(attr);
105 struct subsys_private *subsys_priv = to_subsys_private(kobj);
106 ssize_t ret = 0;
107
108 if (bus_attr->show)
109 ret = bus_attr->show(subsys_priv->bus, buf);
110 return ret;
111}
112
113static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
114 const char *buf, size_t count)
115{
116 struct bus_attribute *bus_attr = to_bus_attr(attr);
117 struct subsys_private *subsys_priv = to_subsys_private(kobj);
118 ssize_t ret = 0;
119
120 if (bus_attr->store)
121 ret = bus_attr->store(subsys_priv->bus, buf, count);
122 return ret;
123}
124
125static const struct sysfs_ops bus_sysfs_ops = {
126 .show = bus_attr_show,
127 .store = bus_attr_store,
128};
129
130int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
131{
132 int error;
133 if (bus_get(bus)) {
134 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
135 bus_put(bus);
136 } else
137 error = -EINVAL;
138 return error;
139}
140EXPORT_SYMBOL_GPL(bus_create_file);
141
142void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
143{
144 if (bus_get(bus)) {
145 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
146 bus_put(bus);
147 }
148}
149EXPORT_SYMBOL_GPL(bus_remove_file);
150
151static void bus_release(struct kobject *kobj)
152{
153 struct subsys_private *priv = to_subsys_private(kobj);
154 struct bus_type *bus = priv->bus;
155
156 kfree(priv);
157 bus->p = NULL;
158}
159
160static struct kobj_type bus_ktype = {
161 .sysfs_ops = &bus_sysfs_ops,
162 .release = bus_release,
163};
164
165static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
166{
167 struct kobj_type *ktype = get_ktype(kobj);
168
169 if (ktype == &bus_ktype)
170 return 1;
171 return 0;
172}
173
174static const struct kset_uevent_ops bus_uevent_ops = {
175 .filter = bus_uevent_filter,
176};
177
178static struct kset *bus_kset;
179
180/* Manually detach a device from its associated driver. */
181static ssize_t unbind_store(struct device_driver *drv, const char *buf,
182 size_t count)
183{
184 struct bus_type *bus = bus_get(drv->bus);
185 struct device *dev;
186 int err = -ENODEV;
187
188 dev = bus_find_device_by_name(bus, NULL, buf);
189 if (dev && dev->driver == drv) {
190 device_driver_detach(dev);
191 err = count;
192 }
193 put_device(dev);
194 bus_put(bus);
195 return err;
196}
197static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
198
199/*
200 * Manually attach a device to a driver.
201 * Note: the driver must want to bind to the device,
202 * it is not possible to override the driver's id table.
203 */
204static ssize_t bind_store(struct device_driver *drv, const char *buf,
205 size_t count)
206{
207 struct bus_type *bus = bus_get(drv->bus);
208 struct device *dev;
209 int err = -ENODEV;
210
211 dev = bus_find_device_by_name(bus, NULL, buf);
212 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
213 err = device_driver_attach(drv, dev);
214
215 if (err > 0) {
216 /* success */
217 err = count;
218 } else if (err == 0) {
219 /* driver didn't accept device */
220 err = -ENODEV;
221 }
222 }
223 put_device(dev);
224 bus_put(bus);
225 return err;
226}
227static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
228
229static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
230{
231 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
232}
233
234static ssize_t drivers_autoprobe_store(struct bus_type *bus,
235 const char *buf, size_t count)
236{
237 if (buf[0] == '0')
238 bus->p->drivers_autoprobe = 0;
239 else
240 bus->p->drivers_autoprobe = 1;
241 return count;
242}
243
244static ssize_t drivers_probe_store(struct bus_type *bus,
245 const char *buf, size_t count)
246{
247 struct device *dev;
248 int err = -EINVAL;
249
250 dev = bus_find_device_by_name(bus, NULL, buf);
251 if (!dev)
252 return -ENODEV;
253 if (bus_rescan_devices_helper(dev, NULL) == 0)
254 err = count;
255 put_device(dev);
256 return err;
257}
258
259static struct device *next_device(struct klist_iter *i)
260{
261 struct klist_node *n = klist_next(i);
262 struct device *dev = NULL;
263 struct device_private *dev_prv;
264
265 if (n) {
266 dev_prv = to_device_private_bus(n);
267 dev = dev_prv->device;
268 }
269 return dev;
270}
271
272/**
273 * bus_for_each_dev - device iterator.
274 * @bus: bus type.
275 * @start: device to start iterating from.
276 * @data: data for the callback.
277 * @fn: function to be called for each device.
278 *
279 * Iterate over @bus's list of devices, and call @fn for each,
280 * passing it @data. If @start is not NULL, we use that device to
281 * begin iterating from.
282 *
283 * We check the return of @fn each time. If it returns anything
284 * other than 0, we break out and return that value.
285 *
286 * NOTE: The device that returns a non-zero value is not retained
287 * in any way, nor is its refcount incremented. If the caller needs
288 * to retain this data, it should do so, and increment the reference
289 * count in the supplied callback.
290 */
291int bus_for_each_dev(struct bus_type *bus, struct device *start,
292 void *data, int (*fn)(struct device *, void *))
293{
294 struct klist_iter i;
295 struct device *dev;
296 int error = 0;
297
298 if (!bus || !bus->p)
299 return -EINVAL;
300
301 klist_iter_init_node(&bus->p->klist_devices, &i,
302 (start ? &start->p->knode_bus : NULL));
303 while (!error && (dev = next_device(&i)))
304 error = fn(dev, data);
305 klist_iter_exit(&i);
306 return error;
307}
308EXPORT_SYMBOL_GPL(bus_for_each_dev);
309
310/**
311 * bus_find_device - device iterator for locating a particular device.
312 * @bus: bus type
313 * @start: Device to begin with
314 * @data: Data to pass to match function
315 * @match: Callback function to check device
316 *
317 * This is similar to the bus_for_each_dev() function above, but it
318 * returns a reference to a device that is 'found' for later use, as
319 * determined by the @match callback.
320 *
321 * The callback should return 0 if the device doesn't match and non-zero
322 * if it does. If the callback returns non-zero, this function will
323 * return to the caller and not iterate over any more devices.
324 */
325struct device *bus_find_device(struct bus_type *bus,
326 struct device *start, const void *data,
327 int (*match)(struct device *dev, const void *data))
328{
329 struct klist_iter i;
330 struct device *dev;
331
332 if (!bus || !bus->p)
333 return NULL;
334
335 klist_iter_init_node(&bus->p->klist_devices, &i,
336 (start ? &start->p->knode_bus : NULL));
337 while ((dev = next_device(&i)))
338 if (match(dev, data) && get_device(dev))
339 break;
340 klist_iter_exit(&i);
341 return dev;
342}
343EXPORT_SYMBOL_GPL(bus_find_device);
344
345/**
346 * subsys_find_device_by_id - find a device with a specific enumeration number
347 * @subsys: subsystem
348 * @id: index 'id' in struct device
349 * @hint: device to check first
350 *
351 * Check the hint's next object and if it is a match return it directly,
352 * otherwise, fall back to a full list search. Either way a reference for
353 * the returned object is taken.
354 */
355struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
356 struct device *hint)
357{
358 struct klist_iter i;
359 struct device *dev;
360
361 if (!subsys)
362 return NULL;
363
364 if (hint) {
365 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
366 dev = next_device(&i);
367 if (dev && dev->id == id && get_device(dev)) {
368 klist_iter_exit(&i);
369 return dev;
370 }
371 klist_iter_exit(&i);
372 }
373
374 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
375 while ((dev = next_device(&i))) {
376 if (dev->id == id && get_device(dev)) {
377 klist_iter_exit(&i);
378 return dev;
379 }
380 }
381 klist_iter_exit(&i);
382 return NULL;
383}
384EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
385
386static struct device_driver *next_driver(struct klist_iter *i)
387{
388 struct klist_node *n = klist_next(i);
389 struct driver_private *drv_priv;
390
391 if (n) {
392 drv_priv = container_of(n, struct driver_private, knode_bus);
393 return drv_priv->driver;
394 }
395 return NULL;
396}
397
398/**
399 * bus_for_each_drv - driver iterator
400 * @bus: bus we're dealing with.
401 * @start: driver to start iterating on.
402 * @data: data to pass to the callback.
403 * @fn: function to call for each driver.
404 *
405 * This is nearly identical to the device iterator above.
406 * We iterate over each driver that belongs to @bus, and call
407 * @fn for each. If @fn returns anything but 0, we break out
408 * and return it. If @start is not NULL, we use it as the head
409 * of the list.
410 *
411 * NOTE: we don't return the driver that returns a non-zero
412 * value, nor do we leave the reference count incremented for that
413 * driver. If the caller needs to know that info, it must set it
414 * in the callback. It must also be sure to increment the refcount
415 * so it doesn't disappear before returning to the caller.
416 */
417int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
418 void *data, int (*fn)(struct device_driver *, void *))
419{
420 struct klist_iter i;
421 struct device_driver *drv;
422 int error = 0;
423
424 if (!bus)
425 return -EINVAL;
426
427 klist_iter_init_node(&bus->p->klist_drivers, &i,
428 start ? &start->p->knode_bus : NULL);
429 while ((drv = next_driver(&i)) && !error)
430 error = fn(drv, data);
431 klist_iter_exit(&i);
432 return error;
433}
434EXPORT_SYMBOL_GPL(bus_for_each_drv);
435
436/**
437 * bus_add_device - add device to bus
438 * @dev: device being added
439 *
440 * - Add device's bus attributes.
441 * - Create links to device's bus.
442 * - Add the device to its bus's list of devices.
443 */
444int bus_add_device(struct device *dev)
445{
446 struct bus_type *bus = bus_get(dev->bus);
447 int error = 0;
448
449 if (bus) {
450 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
451 error = device_add_groups(dev, bus->dev_groups);
452 if (error)
453 goto out_put;
454 error = sysfs_create_link(&bus->p->devices_kset->kobj,
455 &dev->kobj, dev_name(dev));
456 if (error)
457 goto out_groups;
458 error = sysfs_create_link(&dev->kobj,
459 &dev->bus->p->subsys.kobj, "subsystem");
460 if (error)
461 goto out_subsys;
462 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
463 }
464 return 0;
465
466out_subsys:
467 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
468out_groups:
469 device_remove_groups(dev, bus->dev_groups);
470out_put:
471 bus_put(dev->bus);
472 return error;
473}
474
475/**
476 * bus_probe_device - probe drivers for a new device
477 * @dev: device to probe
478 *
479 * - Automatically probe for a driver if the bus allows it.
480 */
481void bus_probe_device(struct device *dev)
482{
483 struct bus_type *bus = dev->bus;
484 struct subsys_interface *sif;
485
486 if (!bus)
487 return;
488
489 if (bus->p->drivers_autoprobe)
490 device_initial_probe(dev);
491
492 mutex_lock(&bus->p->mutex);
493 list_for_each_entry(sif, &bus->p->interfaces, node)
494 if (sif->add_dev)
495 sif->add_dev(dev, sif);
496 mutex_unlock(&bus->p->mutex);
497}
498
499/**
500 * bus_remove_device - remove device from bus
501 * @dev: device to be removed
502 *
503 * - Remove device from all interfaces.
504 * - Remove symlink from bus' directory.
505 * - Delete device from bus's list.
506 * - Detach from its driver.
507 * - Drop reference taken in bus_add_device().
508 */
509void bus_remove_device(struct device *dev)
510{
511 struct bus_type *bus = dev->bus;
512 struct subsys_interface *sif;
513
514 if (!bus)
515 return;
516
517 mutex_lock(&bus->p->mutex);
518 list_for_each_entry(sif, &bus->p->interfaces, node)
519 if (sif->remove_dev)
520 sif->remove_dev(dev, sif);
521 mutex_unlock(&bus->p->mutex);
522
523 sysfs_remove_link(&dev->kobj, "subsystem");
524 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
525 dev_name(dev));
526 device_remove_groups(dev, dev->bus->dev_groups);
527 if (klist_node_attached(&dev->p->knode_bus))
528 klist_del(&dev->p->knode_bus);
529
530 pr_debug("bus: '%s': remove device %s\n",
531 dev->bus->name, dev_name(dev));
532 device_release_driver(dev);
533 bus_put(dev->bus);
534}
535
536static int __must_check add_bind_files(struct device_driver *drv)
537{
538 int ret;
539
540 ret = driver_create_file(drv, &driver_attr_unbind);
541 if (ret == 0) {
542 ret = driver_create_file(drv, &driver_attr_bind);
543 if (ret)
544 driver_remove_file(drv, &driver_attr_unbind);
545 }
546 return ret;
547}
548
549static void remove_bind_files(struct device_driver *drv)
550{
551 driver_remove_file(drv, &driver_attr_bind);
552 driver_remove_file(drv, &driver_attr_unbind);
553}
554
555static BUS_ATTR_WO(drivers_probe);
556static BUS_ATTR_RW(drivers_autoprobe);
557
558static int add_probe_files(struct bus_type *bus)
559{
560 int retval;
561
562 retval = bus_create_file(bus, &bus_attr_drivers_probe);
563 if (retval)
564 goto out;
565
566 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
567 if (retval)
568 bus_remove_file(bus, &bus_attr_drivers_probe);
569out:
570 return retval;
571}
572
573static void remove_probe_files(struct bus_type *bus)
574{
575 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
576 bus_remove_file(bus, &bus_attr_drivers_probe);
577}
578
579static ssize_t uevent_store(struct device_driver *drv, const char *buf,
580 size_t count)
581{
582 int rc;
583
584 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
585 return rc ? rc : count;
586}
587static DRIVER_ATTR_WO(uevent);
588
589/**
590 * bus_add_driver - Add a driver to the bus.
591 * @drv: driver.
592 */
593int bus_add_driver(struct device_driver *drv)
594{
595 struct bus_type *bus;
596 struct driver_private *priv;
597 int error = 0;
598
599 bus = bus_get(drv->bus);
600 if (!bus)
601 return -EINVAL;
602
603 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
604
605 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
606 if (!priv) {
607 error = -ENOMEM;
608 goto out_put_bus;
609 }
610 klist_init(&priv->klist_devices, NULL, NULL);
611 priv->driver = drv;
612 drv->p = priv;
613 priv->kobj.kset = bus->p->drivers_kset;
614 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
615 "%s", drv->name);
616 if (error)
617 goto out_unregister;
618
619 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
620 if (drv->bus->p->drivers_autoprobe) {
621 error = driver_attach(drv);
622 if (error)
623 goto out_unregister;
624 }
625 module_add_driver(drv->owner, drv);
626
627 error = driver_create_file(drv, &driver_attr_uevent);
628 if (error) {
629 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
630 __func__, drv->name);
631 }
632 error = driver_add_groups(drv, bus->drv_groups);
633 if (error) {
634 /* How the hell do we get out of this pickle? Give up */
635 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
636 __func__, drv->name);
637 }
638
639 if (!drv->suppress_bind_attrs) {
640 error = add_bind_files(drv);
641 if (error) {
642 /* Ditto */
643 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
644 __func__, drv->name);
645 }
646 }
647
648 return 0;
649
650out_unregister:
651 kobject_put(&priv->kobj);
652 /* drv->p is freed in driver_release() */
653 drv->p = NULL;
654out_put_bus:
655 bus_put(bus);
656 return error;
657}
658
659/**
660 * bus_remove_driver - delete driver from bus's knowledge.
661 * @drv: driver.
662 *
663 * Detach the driver from the devices it controls, and remove
664 * it from its bus's list of drivers. Finally, we drop the reference
665 * to the bus we took in bus_add_driver().
666 */
667void bus_remove_driver(struct device_driver *drv)
668{
669 if (!drv->bus)
670 return;
671
672 if (!drv->suppress_bind_attrs)
673 remove_bind_files(drv);
674 driver_remove_groups(drv, drv->bus->drv_groups);
675 driver_remove_file(drv, &driver_attr_uevent);
676 klist_remove(&drv->p->knode_bus);
677 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
678 driver_detach(drv);
679 module_remove_driver(drv);
680 kobject_put(&drv->p->kobj);
681 bus_put(drv->bus);
682}
683
684/* Helper for bus_rescan_devices's iter */
685static int __must_check bus_rescan_devices_helper(struct device *dev,
686 void *data)
687{
688 int ret = 0;
689
690 if (!dev->driver) {
691 if (dev->parent && dev->bus->need_parent_lock)
692 device_lock(dev->parent);
693 ret = device_attach(dev);
694 if (dev->parent && dev->bus->need_parent_lock)
695 device_unlock(dev->parent);
696 }
697 return ret < 0 ? ret : 0;
698}
699
700/**
701 * bus_rescan_devices - rescan devices on the bus for possible drivers
702 * @bus: the bus to scan.
703 *
704 * This function will look for devices on the bus with no driver
705 * attached and rescan it against existing drivers to see if it matches
706 * any by calling device_attach() for the unbound devices.
707 */
708int bus_rescan_devices(struct bus_type *bus)
709{
710 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
711}
712EXPORT_SYMBOL_GPL(bus_rescan_devices);
713
714/**
715 * device_reprobe - remove driver for a device and probe for a new driver
716 * @dev: the device to reprobe
717 *
718 * This function detaches the attached driver (if any) for the given
719 * device and restarts the driver probing process. It is intended
720 * to use if probing criteria changed during a devices lifetime and
721 * driver attachment should change accordingly.
722 */
723int device_reprobe(struct device *dev)
724{
725 if (dev->driver)
726 device_driver_detach(dev);
727 return bus_rescan_devices_helper(dev, NULL);
728}
729EXPORT_SYMBOL_GPL(device_reprobe);
730
731/**
732 * find_bus - locate bus by name.
733 * @name: name of bus.
734 *
735 * Call kset_find_obj() to iterate over list of buses to
736 * find a bus by name. Return bus if found.
737 *
738 * Note that kset_find_obj increments bus' reference count.
739 */
740#if 0
741struct bus_type *find_bus(char *name)
742{
743 struct kobject *k = kset_find_obj(bus_kset, name);
744 return k ? to_bus(k) : NULL;
745}
746#endif /* 0 */
747
748static int bus_add_groups(struct bus_type *bus,
749 const struct attribute_group **groups)
750{
751 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
752}
753
754static void bus_remove_groups(struct bus_type *bus,
755 const struct attribute_group **groups)
756{
757 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
758}
759
760static void klist_devices_get(struct klist_node *n)
761{
762 struct device_private *dev_prv = to_device_private_bus(n);
763 struct device *dev = dev_prv->device;
764
765 get_device(dev);
766}
767
768static void klist_devices_put(struct klist_node *n)
769{
770 struct device_private *dev_prv = to_device_private_bus(n);
771 struct device *dev = dev_prv->device;
772
773 put_device(dev);
774}
775
776static ssize_t bus_uevent_store(struct bus_type *bus,
777 const char *buf, size_t count)
778{
779 int rc;
780
781 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
782 return rc ? rc : count;
783}
784/*
785 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
786 * here, but can not use it as earlier in the file we have
787 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
788 * function name.
789 */
790static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
791 bus_uevent_store);
792
793/**
794 * bus_register - register a driver-core subsystem
795 * @bus: bus to register
796 *
797 * Once we have that, we register the bus with the kobject
798 * infrastructure, then register the children subsystems it has:
799 * the devices and drivers that belong to the subsystem.
800 */
801int bus_register(struct bus_type *bus)
802{
803 int retval;
804 struct subsys_private *priv;
805 struct lock_class_key *key = &bus->lock_key;
806
807 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
808 if (!priv)
809 return -ENOMEM;
810
811 priv->bus = bus;
812 bus->p = priv;
813
814 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
815
816 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
817 if (retval)
818 goto out;
819
820 priv->subsys.kobj.kset = bus_kset;
821 priv->subsys.kobj.ktype = &bus_ktype;
822 priv->drivers_autoprobe = 1;
823
824 retval = kset_register(&priv->subsys);
825 if (retval)
826 goto out;
827
828 retval = bus_create_file(bus, &bus_attr_uevent);
829 if (retval)
830 goto bus_uevent_fail;
831
832 priv->devices_kset = kset_create_and_add("devices", NULL,
833 &priv->subsys.kobj);
834 if (!priv->devices_kset) {
835 retval = -ENOMEM;
836 goto bus_devices_fail;
837 }
838
839 priv->drivers_kset = kset_create_and_add("drivers", NULL,
840 &priv->subsys.kobj);
841 if (!priv->drivers_kset) {
842 retval = -ENOMEM;
843 goto bus_drivers_fail;
844 }
845
846 INIT_LIST_HEAD(&priv->interfaces);
847 __mutex_init(&priv->mutex, "subsys mutex", key);
848 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
849 klist_init(&priv->klist_drivers, NULL, NULL);
850
851 retval = add_probe_files(bus);
852 if (retval)
853 goto bus_probe_files_fail;
854
855 retval = bus_add_groups(bus, bus->bus_groups);
856 if (retval)
857 goto bus_groups_fail;
858
859 pr_debug("bus: '%s': registered\n", bus->name);
860 return 0;
861
862bus_groups_fail:
863 remove_probe_files(bus);
864bus_probe_files_fail:
865 kset_unregister(bus->p->drivers_kset);
866bus_drivers_fail:
867 kset_unregister(bus->p->devices_kset);
868bus_devices_fail:
869 bus_remove_file(bus, &bus_attr_uevent);
870bus_uevent_fail:
871 kset_unregister(&bus->p->subsys);
872out:
873 kfree(bus->p);
874 bus->p = NULL;
875 return retval;
876}
877EXPORT_SYMBOL_GPL(bus_register);
878
879/**
880 * bus_unregister - remove a bus from the system
881 * @bus: bus.
882 *
883 * Unregister the child subsystems and the bus itself.
884 * Finally, we call bus_put() to release the refcount
885 */
886void bus_unregister(struct bus_type *bus)
887{
888 pr_debug("bus: '%s': unregistering\n", bus->name);
889 if (bus->dev_root)
890 device_unregister(bus->dev_root);
891 bus_remove_groups(bus, bus->bus_groups);
892 remove_probe_files(bus);
893 kset_unregister(bus->p->drivers_kset);
894 kset_unregister(bus->p->devices_kset);
895 bus_remove_file(bus, &bus_attr_uevent);
896 kset_unregister(&bus->p->subsys);
897}
898EXPORT_SYMBOL_GPL(bus_unregister);
899
900int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
901{
902 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
903}
904EXPORT_SYMBOL_GPL(bus_register_notifier);
905
906int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
907{
908 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
909}
910EXPORT_SYMBOL_GPL(bus_unregister_notifier);
911
912struct kset *bus_get_kset(struct bus_type *bus)
913{
914 return &bus->p->subsys;
915}
916EXPORT_SYMBOL_GPL(bus_get_kset);
917
918struct klist *bus_get_device_klist(struct bus_type *bus)
919{
920 return &bus->p->klist_devices;
921}
922EXPORT_SYMBOL_GPL(bus_get_device_klist);
923
924/*
925 * Yes, this forcibly breaks the klist abstraction temporarily. It
926 * just wants to sort the klist, not change reference counts and
927 * take/drop locks rapidly in the process. It does all this while
928 * holding the lock for the list, so objects can't otherwise be
929 * added/removed while we're swizzling.
930 */
931static void device_insertion_sort_klist(struct device *a, struct list_head *list,
932 int (*compare)(const struct device *a,
933 const struct device *b))
934{
935 struct klist_node *n;
936 struct device_private *dev_prv;
937 struct device *b;
938
939 list_for_each_entry(n, list, n_node) {
940 dev_prv = to_device_private_bus(n);
941 b = dev_prv->device;
942 if (compare(a, b) <= 0) {
943 list_move_tail(&a->p->knode_bus.n_node,
944 &b->p->knode_bus.n_node);
945 return;
946 }
947 }
948 list_move_tail(&a->p->knode_bus.n_node, list);
949}
950
951void bus_sort_breadthfirst(struct bus_type *bus,
952 int (*compare)(const struct device *a,
953 const struct device *b))
954{
955 LIST_HEAD(sorted_devices);
956 struct klist_node *n, *tmp;
957 struct device_private *dev_prv;
958 struct device *dev;
959 struct klist *device_klist;
960
961 device_klist = bus_get_device_klist(bus);
962
963 spin_lock(&device_klist->k_lock);
964 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
965 dev_prv = to_device_private_bus(n);
966 dev = dev_prv->device;
967 device_insertion_sort_klist(dev, &sorted_devices, compare);
968 }
969 list_splice(&sorted_devices, &device_klist->k_list);
970 spin_unlock(&device_klist->k_lock);
971}
972EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
973
974/**
975 * subsys_dev_iter_init - initialize subsys device iterator
976 * @iter: subsys iterator to initialize
977 * @subsys: the subsys we wanna iterate over
978 * @start: the device to start iterating from, if any
979 * @type: device_type of the devices to iterate over, NULL for all
980 *
981 * Initialize subsys iterator @iter such that it iterates over devices
982 * of @subsys. If @start is set, the list iteration will start there,
983 * otherwise if it is NULL, the iteration starts at the beginning of
984 * the list.
985 */
986void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
987 struct device *start, const struct device_type *type)
988{
989 struct klist_node *start_knode = NULL;
990
991 if (start)
992 start_knode = &start->p->knode_bus;
993 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
994 iter->type = type;
995}
996EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
997
998/**
999 * subsys_dev_iter_next - iterate to the next device
1000 * @iter: subsys iterator to proceed
1001 *
1002 * Proceed @iter to the next device and return it. Returns NULL if
1003 * iteration is complete.
1004 *
1005 * The returned device is referenced and won't be released till
1006 * iterator is proceed to the next device or exited. The caller is
1007 * free to do whatever it wants to do with the device including
1008 * calling back into subsys code.
1009 */
1010struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1011{
1012 struct klist_node *knode;
1013 struct device *dev;
1014
1015 for (;;) {
1016 knode = klist_next(&iter->ki);
1017 if (!knode)
1018 return NULL;
1019 dev = to_device_private_bus(knode)->device;
1020 if (!iter->type || iter->type == dev->type)
1021 return dev;
1022 }
1023}
1024EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1025
1026/**
1027 * subsys_dev_iter_exit - finish iteration
1028 * @iter: subsys iterator to finish
1029 *
1030 * Finish an iteration. Always call this function after iteration is
1031 * complete whether the iteration ran till the end or not.
1032 */
1033void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1034{
1035 klist_iter_exit(&iter->ki);
1036}
1037EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1038
1039int subsys_interface_register(struct subsys_interface *sif)
1040{
1041 struct bus_type *subsys;
1042 struct subsys_dev_iter iter;
1043 struct device *dev;
1044
1045 if (!sif || !sif->subsys)
1046 return -ENODEV;
1047
1048 subsys = bus_get(sif->subsys);
1049 if (!subsys)
1050 return -EINVAL;
1051
1052 mutex_lock(&subsys->p->mutex);
1053 list_add_tail(&sif->node, &subsys->p->interfaces);
1054 if (sif->add_dev) {
1055 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1056 while ((dev = subsys_dev_iter_next(&iter)))
1057 sif->add_dev(dev, sif);
1058 subsys_dev_iter_exit(&iter);
1059 }
1060 mutex_unlock(&subsys->p->mutex);
1061
1062 return 0;
1063}
1064EXPORT_SYMBOL_GPL(subsys_interface_register);
1065
1066void subsys_interface_unregister(struct subsys_interface *sif)
1067{
1068 struct bus_type *subsys;
1069 struct subsys_dev_iter iter;
1070 struct device *dev;
1071
1072 if (!sif || !sif->subsys)
1073 return;
1074
1075 subsys = sif->subsys;
1076
1077 mutex_lock(&subsys->p->mutex);
1078 list_del_init(&sif->node);
1079 if (sif->remove_dev) {
1080 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1081 while ((dev = subsys_dev_iter_next(&iter)))
1082 sif->remove_dev(dev, sif);
1083 subsys_dev_iter_exit(&iter);
1084 }
1085 mutex_unlock(&subsys->p->mutex);
1086
1087 bus_put(subsys);
1088}
1089EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1090
1091static void system_root_device_release(struct device *dev)
1092{
1093 kfree(dev);
1094}
1095
1096static int subsys_register(struct bus_type *subsys,
1097 const struct attribute_group **groups,
1098 struct kobject *parent_of_root)
1099{
1100 struct device *dev;
1101 int err;
1102
1103 err = bus_register(subsys);
1104 if (err < 0)
1105 return err;
1106
1107 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1108 if (!dev) {
1109 err = -ENOMEM;
1110 goto err_dev;
1111 }
1112
1113 err = dev_set_name(dev, "%s", subsys->name);
1114 if (err < 0)
1115 goto err_name;
1116
1117 dev->kobj.parent = parent_of_root;
1118 dev->groups = groups;
1119 dev->release = system_root_device_release;
1120
1121 err = device_register(dev);
1122 if (err < 0)
1123 goto err_dev_reg;
1124
1125 subsys->dev_root = dev;
1126 return 0;
1127
1128err_dev_reg:
1129 put_device(dev);
1130 dev = NULL;
1131err_name:
1132 kfree(dev);
1133err_dev:
1134 bus_unregister(subsys);
1135 return err;
1136}
1137
1138/**
1139 * subsys_system_register - register a subsystem at /sys/devices/system/
1140 * @subsys: system subsystem
1141 * @groups: default attributes for the root device
1142 *
1143 * All 'system' subsystems have a /sys/devices/system/<name> root device
1144 * with the name of the subsystem. The root device can carry subsystem-
1145 * wide attributes. All registered devices are below this single root
1146 * device and are named after the subsystem with a simple enumeration
1147 * number appended. The registered devices are not explicitly named;
1148 * only 'id' in the device needs to be set.
1149 *
1150 * Do not use this interface for anything new, it exists for compatibility
1151 * with bad ideas only. New subsystems should use plain subsystems; and
1152 * add the subsystem-wide attributes should be added to the subsystem
1153 * directory itself and not some create fake root-device placed in
1154 * /sys/devices/system/<name>.
1155 */
1156int subsys_system_register(struct bus_type *subsys,
1157 const struct attribute_group **groups)
1158{
1159 return subsys_register(subsys, groups, &system_kset->kobj);
1160}
1161EXPORT_SYMBOL_GPL(subsys_system_register);
1162
1163/**
1164 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1165 * @subsys: virtual subsystem
1166 * @groups: default attributes for the root device
1167 *
1168 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1169 * with the name of the subystem. The root device can carry subsystem-wide
1170 * attributes. All registered devices are below this single root device.
1171 * There's no restriction on device naming. This is for kernel software
1172 * constructs which need sysfs interface.
1173 */
1174int subsys_virtual_register(struct bus_type *subsys,
1175 const struct attribute_group **groups)
1176{
1177 struct kobject *virtual_dir;
1178
1179 virtual_dir = virtual_device_parent(NULL);
1180 if (!virtual_dir)
1181 return -ENOMEM;
1182
1183 return subsys_register(subsys, groups, virtual_dir);
1184}
1185EXPORT_SYMBOL_GPL(subsys_virtual_register);
1186
1187int __init buses_init(void)
1188{
1189 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1190 if (!bus_kset)
1191 return -ENOMEM;
1192
1193 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1194 if (!system_kset)
1195 return -ENOMEM;
1196
1197 return 0;
1198}