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 * 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 module_add_driver(drv->owner, drv);
678
679 error = driver_create_file(drv, &driver_attr_uevent);
680 if (error) {
681 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
682 __func__, drv->name);
683 }
684 error = driver_add_groups(drv, sp->bus->drv_groups);
685 if (error) {
686 /* How the hell do we get out of this pickle? Give up */
687 printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
688 __func__, drv->name);
689 }
690
691 if (!drv->suppress_bind_attrs) {
692 error = add_bind_files(drv);
693 if (error) {
694 /* Ditto */
695 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
696 __func__, drv->name);
697 }
698 }
699
700 return 0;
701
702out_del_list:
703 klist_del(&priv->knode_bus);
704out_unregister:
705 kobject_put(&priv->kobj);
706 /* drv->p is freed in driver_release() */
707 drv->p = NULL;
708out_put_bus:
709 subsys_put(sp);
710 return error;
711}
712
713/**
714 * bus_remove_driver - delete driver from bus's knowledge.
715 * @drv: driver.
716 *
717 * Detach the driver from the devices it controls, and remove
718 * it from its bus's list of drivers. Finally, we drop the reference
719 * to the bus we took in bus_add_driver().
720 */
721void bus_remove_driver(struct device_driver *drv)
722{
723 struct subsys_private *sp = bus_to_subsys(drv->bus);
724
725 if (!sp)
726 return;
727
728 pr_debug("bus: '%s': remove driver %s\n", sp->bus->name, drv->name);
729
730 if (!drv->suppress_bind_attrs)
731 remove_bind_files(drv);
732 driver_remove_groups(drv, sp->bus->drv_groups);
733 driver_remove_file(drv, &driver_attr_uevent);
734 klist_remove(&drv->p->knode_bus);
735 driver_detach(drv);
736 module_remove_driver(drv);
737 kobject_put(&drv->p->kobj);
738
739 /*
740 * Decrement the reference count twice, once for the bus_to_subsys()
741 * call in the start of this function, and the second one from the
742 * reference increment in bus_add_driver()
743 */
744 subsys_put(sp);
745 subsys_put(sp);
746}
747
748/* Helper for bus_rescan_devices's iter */
749static int __must_check bus_rescan_devices_helper(struct device *dev,
750 void *data)
751{
752 int ret = 0;
753
754 if (!dev->driver) {
755 if (dev->parent && dev->bus->need_parent_lock)
756 device_lock(dev->parent);
757 ret = device_attach(dev);
758 if (dev->parent && dev->bus->need_parent_lock)
759 device_unlock(dev->parent);
760 }
761 return ret < 0 ? ret : 0;
762}
763
764/**
765 * bus_rescan_devices - rescan devices on the bus for possible drivers
766 * @bus: the bus to scan.
767 *
768 * This function will look for devices on the bus with no driver
769 * attached and rescan it against existing drivers to see if it matches
770 * any by calling device_attach() for the unbound devices.
771 */
772int bus_rescan_devices(const struct bus_type *bus)
773{
774 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
775}
776EXPORT_SYMBOL_GPL(bus_rescan_devices);
777
778/**
779 * device_reprobe - remove driver for a device and probe for a new driver
780 * @dev: the device to reprobe
781 *
782 * This function detaches the attached driver (if any) for the given
783 * device and restarts the driver probing process. It is intended
784 * to use if probing criteria changed during a devices lifetime and
785 * driver attachment should change accordingly.
786 */
787int device_reprobe(struct device *dev)
788{
789 if (dev->driver)
790 device_driver_detach(dev);
791 return bus_rescan_devices_helper(dev, NULL);
792}
793EXPORT_SYMBOL_GPL(device_reprobe);
794
795static void klist_devices_get(struct klist_node *n)
796{
797 struct device_private *dev_prv = to_device_private_bus(n);
798 struct device *dev = dev_prv->device;
799
800 get_device(dev);
801}
802
803static void klist_devices_put(struct klist_node *n)
804{
805 struct device_private *dev_prv = to_device_private_bus(n);
806 struct device *dev = dev_prv->device;
807
808 put_device(dev);
809}
810
811static ssize_t bus_uevent_store(const struct bus_type *bus,
812 const char *buf, size_t count)
813{
814 struct subsys_private *sp = bus_to_subsys(bus);
815 int ret;
816
817 if (!sp)
818 return -EINVAL;
819
820 ret = kobject_synth_uevent(&sp->subsys.kobj, buf, count);
821 subsys_put(sp);
822
823 if (ret)
824 return ret;
825 return count;
826}
827/*
828 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
829 * here, but can not use it as earlier in the file we have
830 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
831 * function name.
832 */
833static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
834 bus_uevent_store);
835
836/**
837 * bus_register - register a driver-core subsystem
838 * @bus: bus to register
839 *
840 * Once we have that, we register the bus with the kobject
841 * infrastructure, then register the children subsystems it has:
842 * the devices and drivers that belong to the subsystem.
843 */
844int bus_register(const struct bus_type *bus)
845{
846 int retval;
847 struct subsys_private *priv;
848 struct kobject *bus_kobj;
849 struct lock_class_key *key;
850
851 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
852 if (!priv)
853 return -ENOMEM;
854
855 priv->bus = bus;
856
857 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
858
859 bus_kobj = &priv->subsys.kobj;
860 retval = kobject_set_name(bus_kobj, "%s", bus->name);
861 if (retval)
862 goto out;
863
864 bus_kobj->kset = bus_kset;
865 bus_kobj->ktype = &bus_ktype;
866 priv->drivers_autoprobe = 1;
867
868 retval = kset_register(&priv->subsys);
869 if (retval)
870 goto out;
871
872 retval = bus_create_file(bus, &bus_attr_uevent);
873 if (retval)
874 goto bus_uevent_fail;
875
876 priv->devices_kset = kset_create_and_add("devices", NULL, bus_kobj);
877 if (!priv->devices_kset) {
878 retval = -ENOMEM;
879 goto bus_devices_fail;
880 }
881
882 priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj);
883 if (!priv->drivers_kset) {
884 retval = -ENOMEM;
885 goto bus_drivers_fail;
886 }
887
888 INIT_LIST_HEAD(&priv->interfaces);
889 key = &priv->lock_key;
890 lockdep_register_key(key);
891 __mutex_init(&priv->mutex, "subsys mutex", key);
892 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
893 klist_init(&priv->klist_drivers, NULL, NULL);
894
895 retval = add_probe_files(bus);
896 if (retval)
897 goto bus_probe_files_fail;
898
899 retval = sysfs_create_groups(bus_kobj, bus->bus_groups);
900 if (retval)
901 goto bus_groups_fail;
902
903 pr_debug("bus: '%s': registered\n", bus->name);
904 return 0;
905
906bus_groups_fail:
907 remove_probe_files(bus);
908bus_probe_files_fail:
909 kset_unregister(priv->drivers_kset);
910bus_drivers_fail:
911 kset_unregister(priv->devices_kset);
912bus_devices_fail:
913 bus_remove_file(bus, &bus_attr_uevent);
914bus_uevent_fail:
915 kset_unregister(&priv->subsys);
916out:
917 kfree(priv);
918 return retval;
919}
920EXPORT_SYMBOL_GPL(bus_register);
921
922/**
923 * bus_unregister - remove a bus from the system
924 * @bus: bus.
925 *
926 * Unregister the child subsystems and the bus itself.
927 * Finally, we call bus_put() to release the refcount
928 */
929void bus_unregister(const struct bus_type *bus)
930{
931 struct subsys_private *sp = bus_to_subsys(bus);
932 struct kobject *bus_kobj;
933
934 if (!sp)
935 return;
936
937 pr_debug("bus: '%s': unregistering\n", bus->name);
938 if (sp->dev_root)
939 device_unregister(sp->dev_root);
940
941 bus_kobj = &sp->subsys.kobj;
942 sysfs_remove_groups(bus_kobj, bus->bus_groups);
943 remove_probe_files(bus);
944 bus_remove_file(bus, &bus_attr_uevent);
945
946 kset_unregister(sp->drivers_kset);
947 kset_unregister(sp->devices_kset);
948 kset_unregister(&sp->subsys);
949 subsys_put(sp);
950}
951EXPORT_SYMBOL_GPL(bus_unregister);
952
953int bus_register_notifier(const struct bus_type *bus, struct notifier_block *nb)
954{
955 struct subsys_private *sp = bus_to_subsys(bus);
956 int retval;
957
958 if (!sp)
959 return -EINVAL;
960
961 retval = blocking_notifier_chain_register(&sp->bus_notifier, nb);
962 subsys_put(sp);
963 return retval;
964}
965EXPORT_SYMBOL_GPL(bus_register_notifier);
966
967int bus_unregister_notifier(const struct bus_type *bus, struct notifier_block *nb)
968{
969 struct subsys_private *sp = bus_to_subsys(bus);
970 int retval;
971
972 if (!sp)
973 return -EINVAL;
974 retval = blocking_notifier_chain_unregister(&sp->bus_notifier, nb);
975 subsys_put(sp);
976 return retval;
977}
978EXPORT_SYMBOL_GPL(bus_unregister_notifier);
979
980void bus_notify(struct device *dev, enum bus_notifier_event value)
981{
982 struct subsys_private *sp = bus_to_subsys(dev->bus);
983
984 if (!sp)
985 return;
986
987 blocking_notifier_call_chain(&sp->bus_notifier, value, dev);
988 subsys_put(sp);
989}
990
991struct kset *bus_get_kset(const struct bus_type *bus)
992{
993 struct subsys_private *sp = bus_to_subsys(bus);
994 struct kset *kset;
995
996 if (!sp)
997 return NULL;
998
999 kset = &sp->subsys;
1000 subsys_put(sp);
1001
1002 return kset;
1003}
1004EXPORT_SYMBOL_GPL(bus_get_kset);
1005
1006/*
1007 * Yes, this forcibly breaks the klist abstraction temporarily. It
1008 * just wants to sort the klist, not change reference counts and
1009 * take/drop locks rapidly in the process. It does all this while
1010 * holding the lock for the list, so objects can't otherwise be
1011 * added/removed while we're swizzling.
1012 */
1013static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1014 int (*compare)(const struct device *a,
1015 const struct device *b))
1016{
1017 struct klist_node *n;
1018 struct device_private *dev_prv;
1019 struct device *b;
1020
1021 list_for_each_entry(n, list, n_node) {
1022 dev_prv = to_device_private_bus(n);
1023 b = dev_prv->device;
1024 if (compare(a, b) <= 0) {
1025 list_move_tail(&a->p->knode_bus.n_node,
1026 &b->p->knode_bus.n_node);
1027 return;
1028 }
1029 }
1030 list_move_tail(&a->p->knode_bus.n_node, list);
1031}
1032
1033void bus_sort_breadthfirst(const struct bus_type *bus,
1034 int (*compare)(const struct device *a,
1035 const struct device *b))
1036{
1037 struct subsys_private *sp = bus_to_subsys(bus);
1038 LIST_HEAD(sorted_devices);
1039 struct klist_node *n, *tmp;
1040 struct device_private *dev_prv;
1041 struct device *dev;
1042 struct klist *device_klist;
1043
1044 if (!sp)
1045 return;
1046 device_klist = &sp->klist_devices;
1047
1048 spin_lock(&device_klist->k_lock);
1049 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1050 dev_prv = to_device_private_bus(n);
1051 dev = dev_prv->device;
1052 device_insertion_sort_klist(dev, &sorted_devices, compare);
1053 }
1054 list_splice(&sorted_devices, &device_klist->k_list);
1055 spin_unlock(&device_klist->k_lock);
1056 subsys_put(sp);
1057}
1058EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1059
1060struct subsys_dev_iter {
1061 struct klist_iter ki;
1062 const struct device_type *type;
1063};
1064
1065/**
1066 * subsys_dev_iter_init - initialize subsys device iterator
1067 * @iter: subsys iterator to initialize
1068 * @sp: the subsys private (i.e. bus) we wanna iterate over
1069 * @start: the device to start iterating from, if any
1070 * @type: device_type of the devices to iterate over, NULL for all
1071 *
1072 * Initialize subsys iterator @iter such that it iterates over devices
1073 * of @subsys. If @start is set, the list iteration will start there,
1074 * otherwise if it is NULL, the iteration starts at the beginning of
1075 * the list.
1076 */
1077static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct subsys_private *sp,
1078 struct device *start, const struct device_type *type)
1079{
1080 struct klist_node *start_knode = NULL;
1081
1082 if (start)
1083 start_knode = &start->p->knode_bus;
1084 klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
1085 iter->type = type;
1086}
1087
1088/**
1089 * subsys_dev_iter_next - iterate to the next device
1090 * @iter: subsys iterator to proceed
1091 *
1092 * Proceed @iter to the next device and return it. Returns NULL if
1093 * iteration is complete.
1094 *
1095 * The returned device is referenced and won't be released till
1096 * iterator is proceed to the next device or exited. The caller is
1097 * free to do whatever it wants to do with the device including
1098 * calling back into subsys code.
1099 */
1100static struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1101{
1102 struct klist_node *knode;
1103 struct device *dev;
1104
1105 for (;;) {
1106 knode = klist_next(&iter->ki);
1107 if (!knode)
1108 return NULL;
1109 dev = to_device_private_bus(knode)->device;
1110 if (!iter->type || iter->type == dev->type)
1111 return dev;
1112 }
1113}
1114
1115/**
1116 * subsys_dev_iter_exit - finish iteration
1117 * @iter: subsys iterator to finish
1118 *
1119 * Finish an iteration. Always call this function after iteration is
1120 * complete whether the iteration ran till the end or not.
1121 */
1122static void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1123{
1124 klist_iter_exit(&iter->ki);
1125}
1126
1127int subsys_interface_register(struct subsys_interface *sif)
1128{
1129 struct subsys_private *sp;
1130 struct subsys_dev_iter iter;
1131 struct device *dev;
1132
1133 if (!sif || !sif->subsys)
1134 return -ENODEV;
1135
1136 sp = bus_to_subsys(sif->subsys);
1137 if (!sp)
1138 return -EINVAL;
1139
1140 /*
1141 * Reference in sp is now incremented and will be dropped when
1142 * the interface is removed from the bus
1143 */
1144
1145 mutex_lock(&sp->mutex);
1146 list_add_tail(&sif->node, &sp->interfaces);
1147 if (sif->add_dev) {
1148 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1149 while ((dev = subsys_dev_iter_next(&iter)))
1150 sif->add_dev(dev, sif);
1151 subsys_dev_iter_exit(&iter);
1152 }
1153 mutex_unlock(&sp->mutex);
1154
1155 return 0;
1156}
1157EXPORT_SYMBOL_GPL(subsys_interface_register);
1158
1159void subsys_interface_unregister(struct subsys_interface *sif)
1160{
1161 struct subsys_private *sp;
1162 struct subsys_dev_iter iter;
1163 struct device *dev;
1164
1165 if (!sif || !sif->subsys)
1166 return;
1167
1168 sp = bus_to_subsys(sif->subsys);
1169 if (!sp)
1170 return;
1171
1172 mutex_lock(&sp->mutex);
1173 list_del_init(&sif->node);
1174 if (sif->remove_dev) {
1175 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1176 while ((dev = subsys_dev_iter_next(&iter)))
1177 sif->remove_dev(dev, sif);
1178 subsys_dev_iter_exit(&iter);
1179 }
1180 mutex_unlock(&sp->mutex);
1181
1182 /*
1183 * Decrement the reference count twice, once for the bus_to_subsys()
1184 * call in the start of this function, and the second one from the
1185 * reference increment in subsys_interface_register()
1186 */
1187 subsys_put(sp);
1188 subsys_put(sp);
1189}
1190EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1191
1192static void system_root_device_release(struct device *dev)
1193{
1194 kfree(dev);
1195}
1196
1197static int subsys_register(const struct bus_type *subsys,
1198 const struct attribute_group **groups,
1199 struct kobject *parent_of_root)
1200{
1201 struct subsys_private *sp;
1202 struct device *dev;
1203 int err;
1204
1205 err = bus_register(subsys);
1206 if (err < 0)
1207 return err;
1208
1209 sp = bus_to_subsys(subsys);
1210 if (!sp) {
1211 err = -EINVAL;
1212 goto err_sp;
1213 }
1214
1215 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1216 if (!dev) {
1217 err = -ENOMEM;
1218 goto err_dev;
1219 }
1220
1221 err = dev_set_name(dev, "%s", subsys->name);
1222 if (err < 0)
1223 goto err_name;
1224
1225 dev->kobj.parent = parent_of_root;
1226 dev->groups = groups;
1227 dev->release = system_root_device_release;
1228
1229 err = device_register(dev);
1230 if (err < 0)
1231 goto err_dev_reg;
1232
1233 sp->dev_root = dev;
1234 subsys_put(sp);
1235 return 0;
1236
1237err_dev_reg:
1238 put_device(dev);
1239 dev = NULL;
1240err_name:
1241 kfree(dev);
1242err_dev:
1243 subsys_put(sp);
1244err_sp:
1245 bus_unregister(subsys);
1246 return err;
1247}
1248
1249/**
1250 * subsys_system_register - register a subsystem at /sys/devices/system/
1251 * @subsys: system subsystem
1252 * @groups: default attributes for the root device
1253 *
1254 * All 'system' subsystems have a /sys/devices/system/<name> root device
1255 * with the name of the subsystem. The root device can carry subsystem-
1256 * wide attributes. All registered devices are below this single root
1257 * device and are named after the subsystem with a simple enumeration
1258 * number appended. The registered devices are not explicitly named;
1259 * only 'id' in the device needs to be set.
1260 *
1261 * Do not use this interface for anything new, it exists for compatibility
1262 * with bad ideas only. New subsystems should use plain subsystems; and
1263 * add the subsystem-wide attributes should be added to the subsystem
1264 * directory itself and not some create fake root-device placed in
1265 * /sys/devices/system/<name>.
1266 */
1267int subsys_system_register(const struct bus_type *subsys,
1268 const struct attribute_group **groups)
1269{
1270 return subsys_register(subsys, groups, &system_kset->kobj);
1271}
1272EXPORT_SYMBOL_GPL(subsys_system_register);
1273
1274/**
1275 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1276 * @subsys: virtual subsystem
1277 * @groups: default attributes for the root device
1278 *
1279 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1280 * with the name of the subystem. The root device can carry subsystem-wide
1281 * attributes. All registered devices are below this single root device.
1282 * There's no restriction on device naming. This is for kernel software
1283 * constructs which need sysfs interface.
1284 */
1285int subsys_virtual_register(const struct bus_type *subsys,
1286 const struct attribute_group **groups)
1287{
1288 struct kobject *virtual_dir;
1289
1290 virtual_dir = virtual_device_parent(NULL);
1291 if (!virtual_dir)
1292 return -ENOMEM;
1293
1294 return subsys_register(subsys, groups, virtual_dir);
1295}
1296EXPORT_SYMBOL_GPL(subsys_virtual_register);
1297
1298/**
1299 * driver_find - locate driver on a bus by its name.
1300 * @name: name of the driver.
1301 * @bus: bus to scan for the driver.
1302 *
1303 * Call kset_find_obj() to iterate over list of drivers on
1304 * a bus to find driver by name. Return driver if found.
1305 *
1306 * This routine provides no locking to prevent the driver it returns
1307 * from being unregistered or unloaded while the caller is using it.
1308 * The caller is responsible for preventing this.
1309 */
1310struct device_driver *driver_find(const char *name, const struct bus_type *bus)
1311{
1312 struct subsys_private *sp = bus_to_subsys(bus);
1313 struct kobject *k;
1314 struct driver_private *priv;
1315
1316 if (!sp)
1317 return NULL;
1318
1319 k = kset_find_obj(sp->drivers_kset, name);
1320 subsys_put(sp);
1321 if (!k)
1322 return NULL;
1323
1324 priv = to_driver(k);
1325
1326 /* Drop reference added by kset_find_obj() */
1327 kobject_put(k);
1328 return priv->driver;
1329}
1330EXPORT_SYMBOL_GPL(driver_find);
1331
1332/*
1333 * Warning, the value could go to "removed" instantly after calling this function, so be very
1334 * careful when calling it...
1335 */
1336bool bus_is_registered(const struct bus_type *bus)
1337{
1338 struct subsys_private *sp = bus_to_subsys(bus);
1339 bool is_initialized = false;
1340
1341 if (sp) {
1342 is_initialized = true;
1343 subsys_put(sp);
1344 }
1345 return is_initialized;
1346}
1347
1348/**
1349 * bus_get_dev_root - return a pointer to the "device root" of a bus
1350 * @bus: bus to return the device root of.
1351 *
1352 * If a bus has a "device root" structure, return it, WITH THE REFERENCE
1353 * COUNT INCREMENTED.
1354 *
1355 * Note, when finished with the device, a call to put_device() is required.
1356 *
1357 * If the device root is not present (or bus is not a valid pointer), NULL
1358 * will be returned.
1359 */
1360struct device *bus_get_dev_root(const struct bus_type *bus)
1361{
1362 struct subsys_private *sp = bus_to_subsys(bus);
1363 struct device *dev_root;
1364
1365 if (!sp)
1366 return NULL;
1367
1368 dev_root = get_device(sp->dev_root);
1369 subsys_put(sp);
1370 return dev_root;
1371}
1372EXPORT_SYMBOL_GPL(bus_get_dev_root);
1373
1374int __init buses_init(void)
1375{
1376 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1377 if (!bus_kset)
1378 return -ENOMEM;
1379
1380 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1381 if (!system_kset)
1382 return -ENOMEM;
1383
1384 return 0;
1385}
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 /* return -EIO for reading a bus attribute without show() */
156 ssize_t ret = -EIO;
157
158 if (bus_attr->show)
159 ret = bus_attr->show(subsys_priv->bus, buf);
160 return ret;
161}
162
163static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
164 const char *buf, size_t count)
165{
166 struct bus_attribute *bus_attr = to_bus_attr(attr);
167 struct subsys_private *subsys_priv = to_subsys_private(kobj);
168 /* return -EIO for writing a bus attribute without store() */
169 ssize_t ret = -EIO;
170
171 if (bus_attr->store)
172 ret = bus_attr->store(subsys_priv->bus, buf, count);
173 return ret;
174}
175
176static const struct sysfs_ops bus_sysfs_ops = {
177 .show = bus_attr_show,
178 .store = bus_attr_store,
179};
180
181int bus_create_file(const struct bus_type *bus, struct bus_attribute *attr)
182{
183 struct subsys_private *sp = bus_to_subsys(bus);
184 int error;
185
186 if (!sp)
187 return -EINVAL;
188
189 error = sysfs_create_file(&sp->subsys.kobj, &attr->attr);
190
191 subsys_put(sp);
192 return error;
193}
194EXPORT_SYMBOL_GPL(bus_create_file);
195
196void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr)
197{
198 struct subsys_private *sp = bus_to_subsys(bus);
199
200 if (!sp)
201 return;
202
203 sysfs_remove_file(&sp->subsys.kobj, &attr->attr);
204 subsys_put(sp);
205}
206EXPORT_SYMBOL_GPL(bus_remove_file);
207
208static void bus_release(struct kobject *kobj)
209{
210 struct subsys_private *priv = to_subsys_private(kobj);
211
212 lockdep_unregister_key(&priv->lock_key);
213 kfree(priv);
214}
215
216static const struct kobj_type bus_ktype = {
217 .sysfs_ops = &bus_sysfs_ops,
218 .release = bus_release,
219};
220
221static int bus_uevent_filter(const struct kobject *kobj)
222{
223 const struct kobj_type *ktype = get_ktype(kobj);
224
225 if (ktype == &bus_ktype)
226 return 1;
227 return 0;
228}
229
230static const struct kset_uevent_ops bus_uevent_ops = {
231 .filter = bus_uevent_filter,
232};
233
234/* Manually detach a device from its associated driver. */
235static ssize_t unbind_store(struct device_driver *drv, const char *buf,
236 size_t count)
237{
238 const struct bus_type *bus = bus_get(drv->bus);
239 struct device *dev;
240 int err = -ENODEV;
241
242 dev = bus_find_device_by_name(bus, NULL, buf);
243 if (dev && dev->driver == drv) {
244 device_driver_detach(dev);
245 err = count;
246 }
247 put_device(dev);
248 bus_put(bus);
249 return err;
250}
251static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
252
253/*
254 * Manually attach a device to a driver.
255 * Note: the driver must want to bind to the device,
256 * it is not possible to override the driver's id table.
257 */
258static ssize_t bind_store(struct device_driver *drv, const char *buf,
259 size_t count)
260{
261 const struct bus_type *bus = bus_get(drv->bus);
262 struct device *dev;
263 int err = -ENODEV;
264
265 dev = bus_find_device_by_name(bus, NULL, buf);
266 if (dev && driver_match_device(drv, dev)) {
267 err = device_driver_attach(drv, dev);
268 if (!err) {
269 /* success */
270 err = count;
271 }
272 }
273 put_device(dev);
274 bus_put(bus);
275 return err;
276}
277static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
278
279static ssize_t drivers_autoprobe_show(const struct bus_type *bus, char *buf)
280{
281 struct subsys_private *sp = bus_to_subsys(bus);
282 int ret;
283
284 if (!sp)
285 return -EINVAL;
286
287 ret = sysfs_emit(buf, "%d\n", sp->drivers_autoprobe);
288 subsys_put(sp);
289 return ret;
290}
291
292static ssize_t drivers_autoprobe_store(const struct bus_type *bus,
293 const char *buf, size_t count)
294{
295 struct subsys_private *sp = bus_to_subsys(bus);
296
297 if (!sp)
298 return -EINVAL;
299
300 if (buf[0] == '0')
301 sp->drivers_autoprobe = 0;
302 else
303 sp->drivers_autoprobe = 1;
304
305 subsys_put(sp);
306 return count;
307}
308
309static ssize_t drivers_probe_store(const struct bus_type *bus,
310 const char *buf, size_t count)
311{
312 struct device *dev;
313 int err = -EINVAL;
314
315 dev = bus_find_device_by_name(bus, NULL, buf);
316 if (!dev)
317 return -ENODEV;
318 if (bus_rescan_devices_helper(dev, NULL) == 0)
319 err = count;
320 put_device(dev);
321 return err;
322}
323
324static struct device *next_device(struct klist_iter *i)
325{
326 struct klist_node *n = klist_next(i);
327 struct device *dev = NULL;
328 struct device_private *dev_prv;
329
330 if (n) {
331 dev_prv = to_device_private_bus(n);
332 dev = dev_prv->device;
333 }
334 return dev;
335}
336
337/**
338 * bus_for_each_dev - device iterator.
339 * @bus: bus type.
340 * @start: device to start iterating from.
341 * @data: data for the callback.
342 * @fn: function to be called for each device.
343 *
344 * Iterate over @bus's list of devices, and call @fn for each,
345 * passing it @data. If @start is not NULL, we use that device to
346 * begin iterating from.
347 *
348 * We check the return of @fn each time. If it returns anything
349 * other than 0, we break out and return that value.
350 *
351 * NOTE: The device that returns a non-zero value is not retained
352 * in any way, nor is its refcount incremented. If the caller needs
353 * to retain this data, it should do so, and increment the reference
354 * count in the supplied callback.
355 */
356int bus_for_each_dev(const struct bus_type *bus, struct device *start,
357 void *data, int (*fn)(struct device *, void *))
358{
359 struct subsys_private *sp = bus_to_subsys(bus);
360 struct klist_iter i;
361 struct device *dev;
362 int error = 0;
363
364 if (!sp)
365 return -EINVAL;
366
367 klist_iter_init_node(&sp->klist_devices, &i,
368 (start ? &start->p->knode_bus : NULL));
369 while (!error && (dev = next_device(&i)))
370 error = fn(dev, data);
371 klist_iter_exit(&i);
372 subsys_put(sp);
373 return error;
374}
375EXPORT_SYMBOL_GPL(bus_for_each_dev);
376
377/**
378 * bus_find_device - device iterator for locating a particular device.
379 * @bus: bus type
380 * @start: Device to begin with
381 * @data: Data to pass to match function
382 * @match: Callback function to check device
383 *
384 * This is similar to the bus_for_each_dev() function above, but it
385 * returns a reference to a device that is 'found' for later use, as
386 * determined by the @match callback.
387 *
388 * The callback should return 0 if the device doesn't match and non-zero
389 * if it does. If the callback returns non-zero, this function will
390 * return to the caller and not iterate over any more devices.
391 */
392struct device *bus_find_device(const struct bus_type *bus,
393 struct device *start, const void *data,
394 device_match_t match)
395{
396 struct subsys_private *sp = bus_to_subsys(bus);
397 struct klist_iter i;
398 struct device *dev;
399
400 if (!sp)
401 return NULL;
402
403 klist_iter_init_node(&sp->klist_devices, &i,
404 (start ? &start->p->knode_bus : NULL));
405 while ((dev = next_device(&i)))
406 if (match(dev, data) && get_device(dev))
407 break;
408 klist_iter_exit(&i);
409 subsys_put(sp);
410 return dev;
411}
412EXPORT_SYMBOL_GPL(bus_find_device);
413
414static struct device_driver *next_driver(struct klist_iter *i)
415{
416 struct klist_node *n = klist_next(i);
417 struct driver_private *drv_priv;
418
419 if (n) {
420 drv_priv = container_of(n, struct driver_private, knode_bus);
421 return drv_priv->driver;
422 }
423 return NULL;
424}
425
426/**
427 * bus_for_each_drv - driver iterator
428 * @bus: bus we're dealing with.
429 * @start: driver to start iterating on.
430 * @data: data to pass to the callback.
431 * @fn: function to call for each driver.
432 *
433 * This is nearly identical to the device iterator above.
434 * We iterate over each driver that belongs to @bus, and call
435 * @fn for each. If @fn returns anything but 0, we break out
436 * and return it. If @start is not NULL, we use it as the head
437 * of the list.
438 *
439 * NOTE: we don't return the driver that returns a non-zero
440 * value, nor do we leave the reference count incremented for that
441 * driver. If the caller needs to know that info, it must set it
442 * in the callback. It must also be sure to increment the refcount
443 * so it doesn't disappear before returning to the caller.
444 */
445int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start,
446 void *data, int (*fn)(struct device_driver *, void *))
447{
448 struct subsys_private *sp = bus_to_subsys(bus);
449 struct klist_iter i;
450 struct device_driver *drv;
451 int error = 0;
452
453 if (!sp)
454 return -EINVAL;
455
456 klist_iter_init_node(&sp->klist_drivers, &i,
457 start ? &start->p->knode_bus : NULL);
458 while ((drv = next_driver(&i)) && !error)
459 error = fn(drv, data);
460 klist_iter_exit(&i);
461 subsys_put(sp);
462 return error;
463}
464EXPORT_SYMBOL_GPL(bus_for_each_drv);
465
466/**
467 * bus_add_device - add device to bus
468 * @dev: device being added
469 *
470 * - Add device's bus attributes.
471 * - Create links to device's bus.
472 * - Add the device to its bus's list of devices.
473 */
474int bus_add_device(struct device *dev)
475{
476 struct subsys_private *sp = bus_to_subsys(dev->bus);
477 int error;
478
479 if (!sp) {
480 /*
481 * This is a normal operation for many devices that do not
482 * have a bus assigned to them, just say that all went
483 * well.
484 */
485 return 0;
486 }
487
488 /*
489 * Reference in sp is now incremented and will be dropped when
490 * the device is removed from the bus
491 */
492
493 pr_debug("bus: '%s': add device %s\n", sp->bus->name, dev_name(dev));
494
495 error = device_add_groups(dev, sp->bus->dev_groups);
496 if (error)
497 goto out_put;
498
499 error = sysfs_create_link(&sp->devices_kset->kobj, &dev->kobj, dev_name(dev));
500 if (error)
501 goto out_groups;
502
503 error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
504 if (error)
505 goto out_subsys;
506
507 klist_add_tail(&dev->p->knode_bus, &sp->klist_devices);
508 return 0;
509
510out_subsys:
511 sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
512out_groups:
513 device_remove_groups(dev, sp->bus->dev_groups);
514out_put:
515 subsys_put(sp);
516 return error;
517}
518
519/**
520 * bus_probe_device - probe drivers for a new device
521 * @dev: device to probe
522 *
523 * - Automatically probe for a driver if the bus allows it.
524 */
525void bus_probe_device(struct device *dev)
526{
527 struct subsys_private *sp = bus_to_subsys(dev->bus);
528 struct subsys_interface *sif;
529
530 if (!sp)
531 return;
532
533 if (sp->drivers_autoprobe)
534 device_initial_probe(dev);
535
536 mutex_lock(&sp->mutex);
537 list_for_each_entry(sif, &sp->interfaces, node)
538 if (sif->add_dev)
539 sif->add_dev(dev, sif);
540 mutex_unlock(&sp->mutex);
541 subsys_put(sp);
542}
543
544/**
545 * bus_remove_device - remove device from bus
546 * @dev: device to be removed
547 *
548 * - Remove device from all interfaces.
549 * - Remove symlink from bus' directory.
550 * - Delete device from bus's list.
551 * - Detach from its driver.
552 * - Drop reference taken in bus_add_device().
553 */
554void bus_remove_device(struct device *dev)
555{
556 struct subsys_private *sp = bus_to_subsys(dev->bus);
557 struct subsys_interface *sif;
558
559 if (!sp)
560 return;
561
562 mutex_lock(&sp->mutex);
563 list_for_each_entry(sif, &sp->interfaces, node)
564 if (sif->remove_dev)
565 sif->remove_dev(dev, sif);
566 mutex_unlock(&sp->mutex);
567
568 sysfs_remove_link(&dev->kobj, "subsystem");
569 sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
570 device_remove_groups(dev, dev->bus->dev_groups);
571 if (klist_node_attached(&dev->p->knode_bus))
572 klist_del(&dev->p->knode_bus);
573
574 pr_debug("bus: '%s': remove device %s\n",
575 dev->bus->name, dev_name(dev));
576 device_release_driver(dev);
577
578 /*
579 * Decrement the reference count twice, once for the bus_to_subsys()
580 * call in the start of this function, and the second one from the
581 * reference increment in bus_add_device()
582 */
583 subsys_put(sp);
584 subsys_put(sp);
585}
586
587static int __must_check add_bind_files(struct device_driver *drv)
588{
589 int ret;
590
591 ret = driver_create_file(drv, &driver_attr_unbind);
592 if (ret == 0) {
593 ret = driver_create_file(drv, &driver_attr_bind);
594 if (ret)
595 driver_remove_file(drv, &driver_attr_unbind);
596 }
597 return ret;
598}
599
600static void remove_bind_files(struct device_driver *drv)
601{
602 driver_remove_file(drv, &driver_attr_bind);
603 driver_remove_file(drv, &driver_attr_unbind);
604}
605
606static BUS_ATTR_WO(drivers_probe);
607static BUS_ATTR_RW(drivers_autoprobe);
608
609static int add_probe_files(const struct bus_type *bus)
610{
611 int retval;
612
613 retval = bus_create_file(bus, &bus_attr_drivers_probe);
614 if (retval)
615 goto out;
616
617 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
618 if (retval)
619 bus_remove_file(bus, &bus_attr_drivers_probe);
620out:
621 return retval;
622}
623
624static void remove_probe_files(const struct bus_type *bus)
625{
626 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
627 bus_remove_file(bus, &bus_attr_drivers_probe);
628}
629
630static ssize_t uevent_store(struct device_driver *drv, const char *buf,
631 size_t count)
632{
633 int rc;
634
635 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
636 return rc ? rc : count;
637}
638static DRIVER_ATTR_WO(uevent);
639
640/**
641 * bus_add_driver - Add a driver to the bus.
642 * @drv: driver.
643 */
644int bus_add_driver(struct device_driver *drv)
645{
646 struct subsys_private *sp = bus_to_subsys(drv->bus);
647 struct driver_private *priv;
648 int error = 0;
649
650 if (!sp)
651 return -EINVAL;
652
653 /*
654 * Reference in sp is now incremented and will be dropped when
655 * the driver is removed from the bus
656 */
657 pr_debug("bus: '%s': add driver %s\n", sp->bus->name, drv->name);
658
659 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
660 if (!priv) {
661 error = -ENOMEM;
662 goto out_put_bus;
663 }
664 klist_init(&priv->klist_devices, NULL, NULL);
665 priv->driver = drv;
666 drv->p = priv;
667 priv->kobj.kset = sp->drivers_kset;
668 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
669 "%s", drv->name);
670 if (error)
671 goto out_unregister;
672
673 klist_add_tail(&priv->knode_bus, &sp->klist_drivers);
674 if (sp->drivers_autoprobe) {
675 error = driver_attach(drv);
676 if (error)
677 goto out_del_list;
678 }
679 error = module_add_driver(drv->owner, drv);
680 if (error) {
681 printk(KERN_ERR "%s: failed to create module links for %s\n",
682 __func__, drv->name);
683 goto out_detach;
684 }
685
686 error = driver_create_file(drv, &driver_attr_uevent);
687 if (error) {
688 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
689 __func__, drv->name);
690 }
691 error = driver_add_groups(drv, sp->bus->drv_groups);
692 if (error) {
693 /* How the hell do we get out of this pickle? Give up */
694 printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
695 __func__, drv->name);
696 }
697
698 if (!drv->suppress_bind_attrs) {
699 error = add_bind_files(drv);
700 if (error) {
701 /* Ditto */
702 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
703 __func__, drv->name);
704 }
705 }
706
707 return 0;
708
709out_detach:
710 driver_detach(drv);
711out_del_list:
712 klist_del(&priv->knode_bus);
713out_unregister:
714 kobject_put(&priv->kobj);
715 /* drv->p is freed in driver_release() */
716 drv->p = NULL;
717out_put_bus:
718 subsys_put(sp);
719 return error;
720}
721
722/**
723 * bus_remove_driver - delete driver from bus's knowledge.
724 * @drv: driver.
725 *
726 * Detach the driver from the devices it controls, and remove
727 * it from its bus's list of drivers. Finally, we drop the reference
728 * to the bus we took in bus_add_driver().
729 */
730void bus_remove_driver(struct device_driver *drv)
731{
732 struct subsys_private *sp = bus_to_subsys(drv->bus);
733
734 if (!sp)
735 return;
736
737 pr_debug("bus: '%s': remove driver %s\n", sp->bus->name, drv->name);
738
739 if (!drv->suppress_bind_attrs)
740 remove_bind_files(drv);
741 driver_remove_groups(drv, sp->bus->drv_groups);
742 driver_remove_file(drv, &driver_attr_uevent);
743 klist_remove(&drv->p->knode_bus);
744 driver_detach(drv);
745 module_remove_driver(drv);
746 kobject_put(&drv->p->kobj);
747
748 /*
749 * Decrement the reference count twice, once for the bus_to_subsys()
750 * call in the start of this function, and the second one from the
751 * reference increment in bus_add_driver()
752 */
753 subsys_put(sp);
754 subsys_put(sp);
755}
756
757/* Helper for bus_rescan_devices's iter */
758static int __must_check bus_rescan_devices_helper(struct device *dev,
759 void *data)
760{
761 int ret = 0;
762
763 if (!dev->driver) {
764 if (dev->parent && dev->bus->need_parent_lock)
765 device_lock(dev->parent);
766 ret = device_attach(dev);
767 if (dev->parent && dev->bus->need_parent_lock)
768 device_unlock(dev->parent);
769 }
770 return ret < 0 ? ret : 0;
771}
772
773/**
774 * bus_rescan_devices - rescan devices on the bus for possible drivers
775 * @bus: the bus to scan.
776 *
777 * This function will look for devices on the bus with no driver
778 * attached and rescan it against existing drivers to see if it matches
779 * any by calling device_attach() for the unbound devices.
780 */
781int bus_rescan_devices(const struct bus_type *bus)
782{
783 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
784}
785EXPORT_SYMBOL_GPL(bus_rescan_devices);
786
787/**
788 * device_reprobe - remove driver for a device and probe for a new driver
789 * @dev: the device to reprobe
790 *
791 * This function detaches the attached driver (if any) for the given
792 * device and restarts the driver probing process. It is intended
793 * to use if probing criteria changed during a devices lifetime and
794 * driver attachment should change accordingly.
795 */
796int device_reprobe(struct device *dev)
797{
798 if (dev->driver)
799 device_driver_detach(dev);
800 return bus_rescan_devices_helper(dev, NULL);
801}
802EXPORT_SYMBOL_GPL(device_reprobe);
803
804static void klist_devices_get(struct klist_node *n)
805{
806 struct device_private *dev_prv = to_device_private_bus(n);
807 struct device *dev = dev_prv->device;
808
809 get_device(dev);
810}
811
812static void klist_devices_put(struct klist_node *n)
813{
814 struct device_private *dev_prv = to_device_private_bus(n);
815 struct device *dev = dev_prv->device;
816
817 put_device(dev);
818}
819
820static ssize_t bus_uevent_store(const struct bus_type *bus,
821 const char *buf, size_t count)
822{
823 struct subsys_private *sp = bus_to_subsys(bus);
824 int ret;
825
826 if (!sp)
827 return -EINVAL;
828
829 ret = kobject_synth_uevent(&sp->subsys.kobj, buf, count);
830 subsys_put(sp);
831
832 if (ret)
833 return ret;
834 return count;
835}
836/*
837 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
838 * here, but can not use it as earlier in the file we have
839 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
840 * function name.
841 */
842static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
843 bus_uevent_store);
844
845/**
846 * bus_register - register a driver-core subsystem
847 * @bus: bus to register
848 *
849 * Once we have that, we register the bus with the kobject
850 * infrastructure, then register the children subsystems it has:
851 * the devices and drivers that belong to the subsystem.
852 */
853int bus_register(const struct bus_type *bus)
854{
855 int retval;
856 struct subsys_private *priv;
857 struct kobject *bus_kobj;
858 struct lock_class_key *key;
859
860 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
861 if (!priv)
862 return -ENOMEM;
863
864 priv->bus = bus;
865
866 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
867
868 bus_kobj = &priv->subsys.kobj;
869 retval = kobject_set_name(bus_kobj, "%s", bus->name);
870 if (retval)
871 goto out;
872
873 bus_kobj->kset = bus_kset;
874 bus_kobj->ktype = &bus_ktype;
875 priv->drivers_autoprobe = 1;
876
877 retval = kset_register(&priv->subsys);
878 if (retval)
879 goto out;
880
881 retval = bus_create_file(bus, &bus_attr_uevent);
882 if (retval)
883 goto bus_uevent_fail;
884
885 priv->devices_kset = kset_create_and_add("devices", NULL, bus_kobj);
886 if (!priv->devices_kset) {
887 retval = -ENOMEM;
888 goto bus_devices_fail;
889 }
890
891 priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj);
892 if (!priv->drivers_kset) {
893 retval = -ENOMEM;
894 goto bus_drivers_fail;
895 }
896
897 INIT_LIST_HEAD(&priv->interfaces);
898 key = &priv->lock_key;
899 lockdep_register_key(key);
900 __mutex_init(&priv->mutex, "subsys mutex", key);
901 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
902 klist_init(&priv->klist_drivers, NULL, NULL);
903
904 retval = add_probe_files(bus);
905 if (retval)
906 goto bus_probe_files_fail;
907
908 retval = sysfs_create_groups(bus_kobj, bus->bus_groups);
909 if (retval)
910 goto bus_groups_fail;
911
912 pr_debug("bus: '%s': registered\n", bus->name);
913 return 0;
914
915bus_groups_fail:
916 remove_probe_files(bus);
917bus_probe_files_fail:
918 kset_unregister(priv->drivers_kset);
919bus_drivers_fail:
920 kset_unregister(priv->devices_kset);
921bus_devices_fail:
922 bus_remove_file(bus, &bus_attr_uevent);
923bus_uevent_fail:
924 kset_unregister(&priv->subsys);
925 /* Above kset_unregister() will kfree @priv */
926 priv = NULL;
927out:
928 kfree(priv);
929 return retval;
930}
931EXPORT_SYMBOL_GPL(bus_register);
932
933/**
934 * bus_unregister - remove a bus from the system
935 * @bus: bus.
936 *
937 * Unregister the child subsystems and the bus itself.
938 * Finally, we call bus_put() to release the refcount
939 */
940void bus_unregister(const struct bus_type *bus)
941{
942 struct subsys_private *sp = bus_to_subsys(bus);
943 struct kobject *bus_kobj;
944
945 if (!sp)
946 return;
947
948 pr_debug("bus: '%s': unregistering\n", bus->name);
949 if (sp->dev_root)
950 device_unregister(sp->dev_root);
951
952 bus_kobj = &sp->subsys.kobj;
953 sysfs_remove_groups(bus_kobj, bus->bus_groups);
954 remove_probe_files(bus);
955 bus_remove_file(bus, &bus_attr_uevent);
956
957 kset_unregister(sp->drivers_kset);
958 kset_unregister(sp->devices_kset);
959 kset_unregister(&sp->subsys);
960 subsys_put(sp);
961}
962EXPORT_SYMBOL_GPL(bus_unregister);
963
964int bus_register_notifier(const struct bus_type *bus, struct notifier_block *nb)
965{
966 struct subsys_private *sp = bus_to_subsys(bus);
967 int retval;
968
969 if (!sp)
970 return -EINVAL;
971
972 retval = blocking_notifier_chain_register(&sp->bus_notifier, nb);
973 subsys_put(sp);
974 return retval;
975}
976EXPORT_SYMBOL_GPL(bus_register_notifier);
977
978int bus_unregister_notifier(const struct bus_type *bus, struct notifier_block *nb)
979{
980 struct subsys_private *sp = bus_to_subsys(bus);
981 int retval;
982
983 if (!sp)
984 return -EINVAL;
985 retval = blocking_notifier_chain_unregister(&sp->bus_notifier, nb);
986 subsys_put(sp);
987 return retval;
988}
989EXPORT_SYMBOL_GPL(bus_unregister_notifier);
990
991void bus_notify(struct device *dev, enum bus_notifier_event value)
992{
993 struct subsys_private *sp = bus_to_subsys(dev->bus);
994
995 if (!sp)
996 return;
997
998 blocking_notifier_call_chain(&sp->bus_notifier, value, dev);
999 subsys_put(sp);
1000}
1001
1002struct kset *bus_get_kset(const struct bus_type *bus)
1003{
1004 struct subsys_private *sp = bus_to_subsys(bus);
1005 struct kset *kset;
1006
1007 if (!sp)
1008 return NULL;
1009
1010 kset = &sp->subsys;
1011 subsys_put(sp);
1012
1013 return kset;
1014}
1015EXPORT_SYMBOL_GPL(bus_get_kset);
1016
1017/*
1018 * Yes, this forcibly breaks the klist abstraction temporarily. It
1019 * just wants to sort the klist, not change reference counts and
1020 * take/drop locks rapidly in the process. It does all this while
1021 * holding the lock for the list, so objects can't otherwise be
1022 * added/removed while we're swizzling.
1023 */
1024static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1025 int (*compare)(const struct device *a,
1026 const struct device *b))
1027{
1028 struct klist_node *n;
1029 struct device_private *dev_prv;
1030 struct device *b;
1031
1032 list_for_each_entry(n, list, n_node) {
1033 dev_prv = to_device_private_bus(n);
1034 b = dev_prv->device;
1035 if (compare(a, b) <= 0) {
1036 list_move_tail(&a->p->knode_bus.n_node,
1037 &b->p->knode_bus.n_node);
1038 return;
1039 }
1040 }
1041 list_move_tail(&a->p->knode_bus.n_node, list);
1042}
1043
1044void bus_sort_breadthfirst(const struct bus_type *bus,
1045 int (*compare)(const struct device *a,
1046 const struct device *b))
1047{
1048 struct subsys_private *sp = bus_to_subsys(bus);
1049 LIST_HEAD(sorted_devices);
1050 struct klist_node *n, *tmp;
1051 struct device_private *dev_prv;
1052 struct device *dev;
1053 struct klist *device_klist;
1054
1055 if (!sp)
1056 return;
1057 device_klist = &sp->klist_devices;
1058
1059 spin_lock(&device_klist->k_lock);
1060 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1061 dev_prv = to_device_private_bus(n);
1062 dev = dev_prv->device;
1063 device_insertion_sort_klist(dev, &sorted_devices, compare);
1064 }
1065 list_splice(&sorted_devices, &device_klist->k_list);
1066 spin_unlock(&device_klist->k_lock);
1067 subsys_put(sp);
1068}
1069EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1070
1071struct subsys_dev_iter {
1072 struct klist_iter ki;
1073 const struct device_type *type;
1074};
1075
1076/**
1077 * subsys_dev_iter_init - initialize subsys device iterator
1078 * @iter: subsys iterator to initialize
1079 * @sp: the subsys private (i.e. bus) we wanna iterate over
1080 * @start: the device to start iterating from, if any
1081 * @type: device_type of the devices to iterate over, NULL for all
1082 *
1083 * Initialize subsys iterator @iter such that it iterates over devices
1084 * of @subsys. If @start is set, the list iteration will start there,
1085 * otherwise if it is NULL, the iteration starts at the beginning of
1086 * the list.
1087 */
1088static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct subsys_private *sp,
1089 struct device *start, const struct device_type *type)
1090{
1091 struct klist_node *start_knode = NULL;
1092
1093 if (start)
1094 start_knode = &start->p->knode_bus;
1095 klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
1096 iter->type = type;
1097}
1098
1099/**
1100 * subsys_dev_iter_next - iterate to the next device
1101 * @iter: subsys iterator to proceed
1102 *
1103 * Proceed @iter to the next device and return it. Returns NULL if
1104 * iteration is complete.
1105 *
1106 * The returned device is referenced and won't be released till
1107 * iterator is proceed to the next device or exited. The caller is
1108 * free to do whatever it wants to do with the device including
1109 * calling back into subsys code.
1110 */
1111static struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1112{
1113 struct klist_node *knode;
1114 struct device *dev;
1115
1116 for (;;) {
1117 knode = klist_next(&iter->ki);
1118 if (!knode)
1119 return NULL;
1120 dev = to_device_private_bus(knode)->device;
1121 if (!iter->type || iter->type == dev->type)
1122 return dev;
1123 }
1124}
1125
1126/**
1127 * subsys_dev_iter_exit - finish iteration
1128 * @iter: subsys iterator to finish
1129 *
1130 * Finish an iteration. Always call this function after iteration is
1131 * complete whether the iteration ran till the end or not.
1132 */
1133static void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1134{
1135 klist_iter_exit(&iter->ki);
1136}
1137
1138int subsys_interface_register(struct subsys_interface *sif)
1139{
1140 struct subsys_private *sp;
1141 struct subsys_dev_iter iter;
1142 struct device *dev;
1143
1144 if (!sif || !sif->subsys)
1145 return -ENODEV;
1146
1147 sp = bus_to_subsys(sif->subsys);
1148 if (!sp)
1149 return -EINVAL;
1150
1151 /*
1152 * Reference in sp is now incremented and will be dropped when
1153 * the interface is removed from the bus
1154 */
1155
1156 mutex_lock(&sp->mutex);
1157 list_add_tail(&sif->node, &sp->interfaces);
1158 if (sif->add_dev) {
1159 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1160 while ((dev = subsys_dev_iter_next(&iter)))
1161 sif->add_dev(dev, sif);
1162 subsys_dev_iter_exit(&iter);
1163 }
1164 mutex_unlock(&sp->mutex);
1165
1166 return 0;
1167}
1168EXPORT_SYMBOL_GPL(subsys_interface_register);
1169
1170void subsys_interface_unregister(struct subsys_interface *sif)
1171{
1172 struct subsys_private *sp;
1173 struct subsys_dev_iter iter;
1174 struct device *dev;
1175
1176 if (!sif || !sif->subsys)
1177 return;
1178
1179 sp = bus_to_subsys(sif->subsys);
1180 if (!sp)
1181 return;
1182
1183 mutex_lock(&sp->mutex);
1184 list_del_init(&sif->node);
1185 if (sif->remove_dev) {
1186 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1187 while ((dev = subsys_dev_iter_next(&iter)))
1188 sif->remove_dev(dev, sif);
1189 subsys_dev_iter_exit(&iter);
1190 }
1191 mutex_unlock(&sp->mutex);
1192
1193 /*
1194 * Decrement the reference count twice, once for the bus_to_subsys()
1195 * call in the start of this function, and the second one from the
1196 * reference increment in subsys_interface_register()
1197 */
1198 subsys_put(sp);
1199 subsys_put(sp);
1200}
1201EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1202
1203static void system_root_device_release(struct device *dev)
1204{
1205 kfree(dev);
1206}
1207
1208static int subsys_register(const struct bus_type *subsys,
1209 const struct attribute_group **groups,
1210 struct kobject *parent_of_root)
1211{
1212 struct subsys_private *sp;
1213 struct device *dev;
1214 int err;
1215
1216 err = bus_register(subsys);
1217 if (err < 0)
1218 return err;
1219
1220 sp = bus_to_subsys(subsys);
1221 if (!sp) {
1222 err = -EINVAL;
1223 goto err_sp;
1224 }
1225
1226 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1227 if (!dev) {
1228 err = -ENOMEM;
1229 goto err_dev;
1230 }
1231
1232 err = dev_set_name(dev, "%s", subsys->name);
1233 if (err < 0)
1234 goto err_name;
1235
1236 dev->kobj.parent = parent_of_root;
1237 dev->groups = groups;
1238 dev->release = system_root_device_release;
1239
1240 err = device_register(dev);
1241 if (err < 0)
1242 goto err_dev_reg;
1243
1244 sp->dev_root = dev;
1245 subsys_put(sp);
1246 return 0;
1247
1248err_dev_reg:
1249 put_device(dev);
1250 dev = NULL;
1251err_name:
1252 kfree(dev);
1253err_dev:
1254 subsys_put(sp);
1255err_sp:
1256 bus_unregister(subsys);
1257 return err;
1258}
1259
1260/**
1261 * subsys_system_register - register a subsystem at /sys/devices/system/
1262 * @subsys: system subsystem
1263 * @groups: default attributes for the root device
1264 *
1265 * All 'system' subsystems have a /sys/devices/system/<name> root device
1266 * with the name of the subsystem. The root device can carry subsystem-
1267 * wide attributes. All registered devices are below this single root
1268 * device and are named after the subsystem with a simple enumeration
1269 * number appended. The registered devices are not explicitly named;
1270 * only 'id' in the device needs to be set.
1271 *
1272 * Do not use this interface for anything new, it exists for compatibility
1273 * with bad ideas only. New subsystems should use plain subsystems; and
1274 * add the subsystem-wide attributes should be added to the subsystem
1275 * directory itself and not some create fake root-device placed in
1276 * /sys/devices/system/<name>.
1277 */
1278int subsys_system_register(const struct bus_type *subsys,
1279 const struct attribute_group **groups)
1280{
1281 return subsys_register(subsys, groups, &system_kset->kobj);
1282}
1283EXPORT_SYMBOL_GPL(subsys_system_register);
1284
1285/**
1286 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1287 * @subsys: virtual subsystem
1288 * @groups: default attributes for the root device
1289 *
1290 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1291 * with the name of the subystem. The root device can carry subsystem-wide
1292 * attributes. All registered devices are below this single root device.
1293 * There's no restriction on device naming. This is for kernel software
1294 * constructs which need sysfs interface.
1295 */
1296int subsys_virtual_register(const struct bus_type *subsys,
1297 const struct attribute_group **groups)
1298{
1299 struct kobject *virtual_dir;
1300
1301 virtual_dir = virtual_device_parent();
1302 if (!virtual_dir)
1303 return -ENOMEM;
1304
1305 return subsys_register(subsys, groups, virtual_dir);
1306}
1307EXPORT_SYMBOL_GPL(subsys_virtual_register);
1308
1309/**
1310 * driver_find - locate driver on a bus by its name.
1311 * @name: name of the driver.
1312 * @bus: bus to scan for the driver.
1313 *
1314 * Call kset_find_obj() to iterate over list of drivers on
1315 * a bus to find driver by name. Return driver if found.
1316 *
1317 * This routine provides no locking to prevent the driver it returns
1318 * from being unregistered or unloaded while the caller is using it.
1319 * The caller is responsible for preventing this.
1320 */
1321struct device_driver *driver_find(const char *name, const struct bus_type *bus)
1322{
1323 struct subsys_private *sp = bus_to_subsys(bus);
1324 struct kobject *k;
1325 struct driver_private *priv;
1326
1327 if (!sp)
1328 return NULL;
1329
1330 k = kset_find_obj(sp->drivers_kset, name);
1331 subsys_put(sp);
1332 if (!k)
1333 return NULL;
1334
1335 priv = to_driver(k);
1336
1337 /* Drop reference added by kset_find_obj() */
1338 kobject_put(k);
1339 return priv->driver;
1340}
1341EXPORT_SYMBOL_GPL(driver_find);
1342
1343/*
1344 * Warning, the value could go to "removed" instantly after calling this function, so be very
1345 * careful when calling it...
1346 */
1347bool bus_is_registered(const struct bus_type *bus)
1348{
1349 struct subsys_private *sp = bus_to_subsys(bus);
1350 bool is_initialized = false;
1351
1352 if (sp) {
1353 is_initialized = true;
1354 subsys_put(sp);
1355 }
1356 return is_initialized;
1357}
1358
1359/**
1360 * bus_get_dev_root - return a pointer to the "device root" of a bus
1361 * @bus: bus to return the device root of.
1362 *
1363 * If a bus has a "device root" structure, return it, WITH THE REFERENCE
1364 * COUNT INCREMENTED.
1365 *
1366 * Note, when finished with the device, a call to put_device() is required.
1367 *
1368 * If the device root is not present (or bus is not a valid pointer), NULL
1369 * will be returned.
1370 */
1371struct device *bus_get_dev_root(const struct bus_type *bus)
1372{
1373 struct subsys_private *sp = bus_to_subsys(bus);
1374 struct device *dev_root;
1375
1376 if (!sp)
1377 return NULL;
1378
1379 dev_root = get_device(sp->dev_root);
1380 subsys_put(sp);
1381 return dev_root;
1382}
1383EXPORT_SYMBOL_GPL(bus_get_dev_root);
1384
1385int __init buses_init(void)
1386{
1387 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1388 if (!bus_kset)
1389 return -ENOMEM;
1390
1391 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1392 if (!system_kset) {
1393 /* Do error handling here as devices_init() do */
1394 kset_unregister(bus_kset);
1395 bus_kset = NULL;
1396 pr_err("%s: failed to create and add kset 'bus'\n", __func__);
1397 return -ENOMEM;
1398 }
1399
1400 return 0;
1401}