Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * bus.c - bus driver management
4 *
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
8 * Copyright (c) 2007 Novell Inc.
9 */
10
11#include <linux/async.h>
12#include <linux/device/bus.h>
13#include <linux/device.h>
14#include <linux/module.h>
15#include <linux/errno.h>
16#include <linux/slab.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/mutex.h>
20#include <linux/sysfs.h>
21#include "base.h"
22#include "power/power.h"
23
24/* /sys/devices/system */
25static struct kset *system_kset;
26
27#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
28
29/*
30 * sysfs bindings for drivers
31 */
32
33#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
34
35#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
36 struct driver_attribute driver_attr_##_name = \
37 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
38
39static int __must_check bus_rescan_devices_helper(struct device *dev,
40 void *data);
41
42static struct bus_type *bus_get(struct bus_type *bus)
43{
44 if (bus) {
45 kset_get(&bus->p->subsys);
46 return bus;
47 }
48 return NULL;
49}
50
51static void bus_put(struct bus_type *bus)
52{
53 if (bus)
54 kset_put(&bus->p->subsys);
55}
56
57static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
58 char *buf)
59{
60 struct driver_attribute *drv_attr = to_drv_attr(attr);
61 struct driver_private *drv_priv = to_driver(kobj);
62 ssize_t ret = -EIO;
63
64 if (drv_attr->show)
65 ret = drv_attr->show(drv_priv->driver, buf);
66 return ret;
67}
68
69static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
70 const char *buf, size_t count)
71{
72 struct driver_attribute *drv_attr = to_drv_attr(attr);
73 struct driver_private *drv_priv = to_driver(kobj);
74 ssize_t ret = -EIO;
75
76 if (drv_attr->store)
77 ret = drv_attr->store(drv_priv->driver, buf, count);
78 return ret;
79}
80
81static const struct sysfs_ops driver_sysfs_ops = {
82 .show = drv_attr_show,
83 .store = drv_attr_store,
84};
85
86static void driver_release(struct kobject *kobj)
87{
88 struct driver_private *drv_priv = to_driver(kobj);
89
90 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
91 kfree(drv_priv);
92}
93
94static struct kobj_type driver_ktype = {
95 .sysfs_ops = &driver_sysfs_ops,
96 .release = driver_release,
97};
98
99/*
100 * sysfs bindings for buses
101 */
102static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
103 char *buf)
104{
105 struct bus_attribute *bus_attr = to_bus_attr(attr);
106 struct subsys_private *subsys_priv = to_subsys_private(kobj);
107 ssize_t ret = 0;
108
109 if (bus_attr->show)
110 ret = bus_attr->show(subsys_priv->bus, buf);
111 return ret;
112}
113
114static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
115 const char *buf, size_t count)
116{
117 struct bus_attribute *bus_attr = to_bus_attr(attr);
118 struct subsys_private *subsys_priv = to_subsys_private(kobj);
119 ssize_t ret = 0;
120
121 if (bus_attr->store)
122 ret = bus_attr->store(subsys_priv->bus, buf, count);
123 return ret;
124}
125
126static const struct sysfs_ops bus_sysfs_ops = {
127 .show = bus_attr_show,
128 .store = bus_attr_store,
129};
130
131int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
132{
133 int error;
134 if (bus_get(bus)) {
135 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
136 bus_put(bus);
137 } else
138 error = -EINVAL;
139 return error;
140}
141EXPORT_SYMBOL_GPL(bus_create_file);
142
143void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
144{
145 if (bus_get(bus)) {
146 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
147 bus_put(bus);
148 }
149}
150EXPORT_SYMBOL_GPL(bus_remove_file);
151
152static void bus_release(struct kobject *kobj)
153{
154 struct subsys_private *priv = to_subsys_private(kobj);
155 struct bus_type *bus = priv->bus;
156
157 kfree(priv);
158 bus->p = NULL;
159}
160
161static struct kobj_type bus_ktype = {
162 .sysfs_ops = &bus_sysfs_ops,
163 .release = bus_release,
164};
165
166static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
167{
168 struct kobj_type *ktype = get_ktype(kobj);
169
170 if (ktype == &bus_ktype)
171 return 1;
172 return 0;
173}
174
175static const struct kset_uevent_ops bus_uevent_ops = {
176 .filter = bus_uevent_filter,
177};
178
179static struct kset *bus_kset;
180
181/* Manually detach a device from its associated driver. */
182static ssize_t unbind_store(struct device_driver *drv, const char *buf,
183 size_t count)
184{
185 struct bus_type *bus = bus_get(drv->bus);
186 struct device *dev;
187 int err = -ENODEV;
188
189 dev = bus_find_device_by_name(bus, NULL, buf);
190 if (dev && dev->driver == drv) {
191 device_driver_detach(dev);
192 err = count;
193 }
194 put_device(dev);
195 bus_put(bus);
196 return err;
197}
198static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
199
200/*
201 * Manually attach a device to a driver.
202 * Note: the driver must want to bind to the device,
203 * it is not possible to override the driver's id table.
204 */
205static ssize_t bind_store(struct device_driver *drv, const char *buf,
206 size_t count)
207{
208 struct bus_type *bus = bus_get(drv->bus);
209 struct device *dev;
210 int err = -ENODEV;
211
212 dev = bus_find_device_by_name(bus, NULL, buf);
213 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
214 err = device_driver_attach(drv, dev);
215
216 if (err > 0) {
217 /* success */
218 err = count;
219 } else if (err == 0) {
220 /* driver didn't accept device */
221 err = -ENODEV;
222 }
223 }
224 put_device(dev);
225 bus_put(bus);
226 return err;
227}
228static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
229
230static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
231{
232 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
233}
234
235static ssize_t drivers_autoprobe_store(struct bus_type *bus,
236 const char *buf, size_t count)
237{
238 if (buf[0] == '0')
239 bus->p->drivers_autoprobe = 0;
240 else
241 bus->p->drivers_autoprobe = 1;
242 return count;
243}
244
245static ssize_t drivers_probe_store(struct bus_type *bus,
246 const char *buf, size_t count)
247{
248 struct device *dev;
249 int err = -EINVAL;
250
251 dev = bus_find_device_by_name(bus, NULL, buf);
252 if (!dev)
253 return -ENODEV;
254 if (bus_rescan_devices_helper(dev, NULL) == 0)
255 err = count;
256 put_device(dev);
257 return err;
258}
259
260static struct device *next_device(struct klist_iter *i)
261{
262 struct klist_node *n = klist_next(i);
263 struct device *dev = NULL;
264 struct device_private *dev_prv;
265
266 if (n) {
267 dev_prv = to_device_private_bus(n);
268 dev = dev_prv->device;
269 }
270 return dev;
271}
272
273/**
274 * bus_for_each_dev - device iterator.
275 * @bus: bus type.
276 * @start: device to start iterating from.
277 * @data: data for the callback.
278 * @fn: function to be called for each device.
279 *
280 * Iterate over @bus's list of devices, and call @fn for each,
281 * passing it @data. If @start is not NULL, we use that device to
282 * begin iterating from.
283 *
284 * We check the return of @fn each time. If it returns anything
285 * other than 0, we break out and return that value.
286 *
287 * NOTE: The device that returns a non-zero value is not retained
288 * in any way, nor is its refcount incremented. If the caller needs
289 * to retain this data, it should do so, and increment the reference
290 * count in the supplied callback.
291 */
292int bus_for_each_dev(struct bus_type *bus, struct device *start,
293 void *data, int (*fn)(struct device *, void *))
294{
295 struct klist_iter i;
296 struct device *dev;
297 int error = 0;
298
299 if (!bus || !bus->p)
300 return -EINVAL;
301
302 klist_iter_init_node(&bus->p->klist_devices, &i,
303 (start ? &start->p->knode_bus : NULL));
304 while (!error && (dev = next_device(&i)))
305 error = fn(dev, data);
306 klist_iter_exit(&i);
307 return error;
308}
309EXPORT_SYMBOL_GPL(bus_for_each_dev);
310
311/**
312 * bus_find_device - device iterator for locating a particular device.
313 * @bus: bus type
314 * @start: Device to begin with
315 * @data: Data to pass to match function
316 * @match: Callback function to check device
317 *
318 * This is similar to the bus_for_each_dev() function above, but it
319 * returns a reference to a device that is 'found' for later use, as
320 * determined by the @match callback.
321 *
322 * The callback should return 0 if the device doesn't match and non-zero
323 * if it does. If the callback returns non-zero, this function will
324 * return to the caller and not iterate over any more devices.
325 */
326struct device *bus_find_device(struct bus_type *bus,
327 struct device *start, const void *data,
328 int (*match)(struct device *dev, const void *data))
329{
330 struct klist_iter i;
331 struct device *dev;
332
333 if (!bus || !bus->p)
334 return NULL;
335
336 klist_iter_init_node(&bus->p->klist_devices, &i,
337 (start ? &start->p->knode_bus : NULL));
338 while ((dev = next_device(&i)))
339 if (match(dev, data) && get_device(dev))
340 break;
341 klist_iter_exit(&i);
342 return dev;
343}
344EXPORT_SYMBOL_GPL(bus_find_device);
345
346/**
347 * subsys_find_device_by_id - find a device with a specific enumeration number
348 * @subsys: subsystem
349 * @id: index 'id' in struct device
350 * @hint: device to check first
351 *
352 * Check the hint's next object and if it is a match return it directly,
353 * otherwise, fall back to a full list search. Either way a reference for
354 * the returned object is taken.
355 */
356struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
357 struct device *hint)
358{
359 struct klist_iter i;
360 struct device *dev;
361
362 if (!subsys)
363 return NULL;
364
365 if (hint) {
366 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
367 dev = next_device(&i);
368 if (dev && dev->id == id && get_device(dev)) {
369 klist_iter_exit(&i);
370 return dev;
371 }
372 klist_iter_exit(&i);
373 }
374
375 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
376 while ((dev = next_device(&i))) {
377 if (dev->id == id && get_device(dev)) {
378 klist_iter_exit(&i);
379 return dev;
380 }
381 }
382 klist_iter_exit(&i);
383 return NULL;
384}
385EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
386
387static struct device_driver *next_driver(struct klist_iter *i)
388{
389 struct klist_node *n = klist_next(i);
390 struct driver_private *drv_priv;
391
392 if (n) {
393 drv_priv = container_of(n, struct driver_private, knode_bus);
394 return drv_priv->driver;
395 }
396 return NULL;
397}
398
399/**
400 * bus_for_each_drv - driver iterator
401 * @bus: bus we're dealing with.
402 * @start: driver to start iterating on.
403 * @data: data to pass to the callback.
404 * @fn: function to call for each driver.
405 *
406 * This is nearly identical to the device iterator above.
407 * We iterate over each driver that belongs to @bus, and call
408 * @fn for each. If @fn returns anything but 0, we break out
409 * and return it. If @start is not NULL, we use it as the head
410 * of the list.
411 *
412 * NOTE: we don't return the driver that returns a non-zero
413 * value, nor do we leave the reference count incremented for that
414 * driver. If the caller needs to know that info, it must set it
415 * in the callback. It must also be sure to increment the refcount
416 * so it doesn't disappear before returning to the caller.
417 */
418int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
419 void *data, int (*fn)(struct device_driver *, void *))
420{
421 struct klist_iter i;
422 struct device_driver *drv;
423 int error = 0;
424
425 if (!bus)
426 return -EINVAL;
427
428 klist_iter_init_node(&bus->p->klist_drivers, &i,
429 start ? &start->p->knode_bus : NULL);
430 while ((drv = next_driver(&i)) && !error)
431 error = fn(drv, data);
432 klist_iter_exit(&i);
433 return error;
434}
435EXPORT_SYMBOL_GPL(bus_for_each_drv);
436
437/**
438 * bus_add_device - add device to bus
439 * @dev: device being added
440 *
441 * - Add device's bus attributes.
442 * - Create links to device's bus.
443 * - Add the device to its bus's list of devices.
444 */
445int bus_add_device(struct device *dev)
446{
447 struct bus_type *bus = bus_get(dev->bus);
448 int error = 0;
449
450 if (bus) {
451 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
452 error = device_add_groups(dev, bus->dev_groups);
453 if (error)
454 goto out_put;
455 error = sysfs_create_link(&bus->p->devices_kset->kobj,
456 &dev->kobj, dev_name(dev));
457 if (error)
458 goto out_groups;
459 error = sysfs_create_link(&dev->kobj,
460 &dev->bus->p->subsys.kobj, "subsystem");
461 if (error)
462 goto out_subsys;
463 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
464 }
465 return 0;
466
467out_subsys:
468 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
469out_groups:
470 device_remove_groups(dev, bus->dev_groups);
471out_put:
472 bus_put(dev->bus);
473 return error;
474}
475
476/**
477 * bus_probe_device - probe drivers for a new device
478 * @dev: device to probe
479 *
480 * - Automatically probe for a driver if the bus allows it.
481 */
482void bus_probe_device(struct device *dev)
483{
484 struct bus_type *bus = dev->bus;
485 struct subsys_interface *sif;
486
487 if (!bus)
488 return;
489
490 if (bus->p->drivers_autoprobe)
491 device_initial_probe(dev);
492
493 mutex_lock(&bus->p->mutex);
494 list_for_each_entry(sif, &bus->p->interfaces, node)
495 if (sif->add_dev)
496 sif->add_dev(dev, sif);
497 mutex_unlock(&bus->p->mutex);
498}
499
500/**
501 * bus_remove_device - remove device from bus
502 * @dev: device to be removed
503 *
504 * - Remove device from all interfaces.
505 * - Remove symlink from bus' directory.
506 * - Delete device from bus's list.
507 * - Detach from its driver.
508 * - Drop reference taken in bus_add_device().
509 */
510void bus_remove_device(struct device *dev)
511{
512 struct bus_type *bus = dev->bus;
513 struct subsys_interface *sif;
514
515 if (!bus)
516 return;
517
518 mutex_lock(&bus->p->mutex);
519 list_for_each_entry(sif, &bus->p->interfaces, node)
520 if (sif->remove_dev)
521 sif->remove_dev(dev, sif);
522 mutex_unlock(&bus->p->mutex);
523
524 sysfs_remove_link(&dev->kobj, "subsystem");
525 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
526 dev_name(dev));
527 device_remove_groups(dev, dev->bus->dev_groups);
528 if (klist_node_attached(&dev->p->knode_bus))
529 klist_del(&dev->p->knode_bus);
530
531 pr_debug("bus: '%s': remove device %s\n",
532 dev->bus->name, dev_name(dev));
533 device_release_driver(dev);
534 bus_put(dev->bus);
535}
536
537static int __must_check add_bind_files(struct device_driver *drv)
538{
539 int ret;
540
541 ret = driver_create_file(drv, &driver_attr_unbind);
542 if (ret == 0) {
543 ret = driver_create_file(drv, &driver_attr_bind);
544 if (ret)
545 driver_remove_file(drv, &driver_attr_unbind);
546 }
547 return ret;
548}
549
550static void remove_bind_files(struct device_driver *drv)
551{
552 driver_remove_file(drv, &driver_attr_bind);
553 driver_remove_file(drv, &driver_attr_unbind);
554}
555
556static BUS_ATTR_WO(drivers_probe);
557static BUS_ATTR_RW(drivers_autoprobe);
558
559static int add_probe_files(struct bus_type *bus)
560{
561 int retval;
562
563 retval = bus_create_file(bus, &bus_attr_drivers_probe);
564 if (retval)
565 goto out;
566
567 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
568 if (retval)
569 bus_remove_file(bus, &bus_attr_drivers_probe);
570out:
571 return retval;
572}
573
574static void remove_probe_files(struct bus_type *bus)
575{
576 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
577 bus_remove_file(bus, &bus_attr_drivers_probe);
578}
579
580static ssize_t uevent_store(struct device_driver *drv, const char *buf,
581 size_t count)
582{
583 int rc;
584
585 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
586 return rc ? rc : count;
587}
588static DRIVER_ATTR_WO(uevent);
589
590/**
591 * bus_add_driver - Add a driver to the bus.
592 * @drv: driver.
593 */
594int bus_add_driver(struct device_driver *drv)
595{
596 struct bus_type *bus;
597 struct driver_private *priv;
598 int error = 0;
599
600 bus = bus_get(drv->bus);
601 if (!bus)
602 return -EINVAL;
603
604 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
605
606 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
607 if (!priv) {
608 error = -ENOMEM;
609 goto out_put_bus;
610 }
611 klist_init(&priv->klist_devices, NULL, NULL);
612 priv->driver = drv;
613 drv->p = priv;
614 priv->kobj.kset = bus->p->drivers_kset;
615 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
616 "%s", drv->name);
617 if (error)
618 goto out_unregister;
619
620 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
621 if (drv->bus->p->drivers_autoprobe) {
622 error = driver_attach(drv);
623 if (error)
624 goto out_unregister;
625 }
626 module_add_driver(drv->owner, drv);
627
628 error = driver_create_file(drv, &driver_attr_uevent);
629 if (error) {
630 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
631 __func__, drv->name);
632 }
633 error = driver_add_groups(drv, bus->drv_groups);
634 if (error) {
635 /* How the hell do we get out of this pickle? Give up */
636 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
637 __func__, drv->name);
638 }
639
640 if (!drv->suppress_bind_attrs) {
641 error = add_bind_files(drv);
642 if (error) {
643 /* Ditto */
644 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
645 __func__, drv->name);
646 }
647 }
648
649 return 0;
650
651out_unregister:
652 kobject_put(&priv->kobj);
653 /* drv->p is freed in driver_release() */
654 drv->p = NULL;
655out_put_bus:
656 bus_put(bus);
657 return error;
658}
659
660/**
661 * bus_remove_driver - delete driver from bus's knowledge.
662 * @drv: driver.
663 *
664 * Detach the driver from the devices it controls, and remove
665 * it from its bus's list of drivers. Finally, we drop the reference
666 * to the bus we took in bus_add_driver().
667 */
668void bus_remove_driver(struct device_driver *drv)
669{
670 if (!drv->bus)
671 return;
672
673 if (!drv->suppress_bind_attrs)
674 remove_bind_files(drv);
675 driver_remove_groups(drv, drv->bus->drv_groups);
676 driver_remove_file(drv, &driver_attr_uevent);
677 klist_remove(&drv->p->knode_bus);
678 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
679 driver_detach(drv);
680 module_remove_driver(drv);
681 kobject_put(&drv->p->kobj);
682 bus_put(drv->bus);
683}
684
685/* Helper for bus_rescan_devices's iter */
686static int __must_check bus_rescan_devices_helper(struct device *dev,
687 void *data)
688{
689 int ret = 0;
690
691 if (!dev->driver) {
692 if (dev->parent && dev->bus->need_parent_lock)
693 device_lock(dev->parent);
694 ret = device_attach(dev);
695 if (dev->parent && dev->bus->need_parent_lock)
696 device_unlock(dev->parent);
697 }
698 return ret < 0 ? ret : 0;
699}
700
701/**
702 * bus_rescan_devices - rescan devices on the bus for possible drivers
703 * @bus: the bus to scan.
704 *
705 * This function will look for devices on the bus with no driver
706 * attached and rescan it against existing drivers to see if it matches
707 * any by calling device_attach() for the unbound devices.
708 */
709int bus_rescan_devices(struct bus_type *bus)
710{
711 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
712}
713EXPORT_SYMBOL_GPL(bus_rescan_devices);
714
715/**
716 * device_reprobe - remove driver for a device and probe for a new driver
717 * @dev: the device to reprobe
718 *
719 * This function detaches the attached driver (if any) for the given
720 * device and restarts the driver probing process. It is intended
721 * to use if probing criteria changed during a devices lifetime and
722 * driver attachment should change accordingly.
723 */
724int device_reprobe(struct device *dev)
725{
726 if (dev->driver)
727 device_driver_detach(dev);
728 return bus_rescan_devices_helper(dev, NULL);
729}
730EXPORT_SYMBOL_GPL(device_reprobe);
731
732/**
733 * find_bus - locate bus by name.
734 * @name: name of bus.
735 *
736 * Call kset_find_obj() to iterate over list of buses to
737 * find a bus by name. Return bus if found.
738 *
739 * Note that kset_find_obj increments bus' reference count.
740 */
741#if 0
742struct bus_type *find_bus(char *name)
743{
744 struct kobject *k = kset_find_obj(bus_kset, name);
745 return k ? to_bus(k) : NULL;
746}
747#endif /* 0 */
748
749static int bus_add_groups(struct bus_type *bus,
750 const struct attribute_group **groups)
751{
752 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
753}
754
755static void bus_remove_groups(struct bus_type *bus,
756 const struct attribute_group **groups)
757{
758 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
759}
760
761static void klist_devices_get(struct klist_node *n)
762{
763 struct device_private *dev_prv = to_device_private_bus(n);
764 struct device *dev = dev_prv->device;
765
766 get_device(dev);
767}
768
769static void klist_devices_put(struct klist_node *n)
770{
771 struct device_private *dev_prv = to_device_private_bus(n);
772 struct device *dev = dev_prv->device;
773
774 put_device(dev);
775}
776
777static ssize_t bus_uevent_store(struct bus_type *bus,
778 const char *buf, size_t count)
779{
780 int rc;
781
782 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
783 return rc ? rc : count;
784}
785/*
786 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
787 * here, but can not use it as earlier in the file we have
788 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
789 * function name.
790 */
791static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
792 bus_uevent_store);
793
794/**
795 * bus_register - register a driver-core subsystem
796 * @bus: bus to register
797 *
798 * Once we have that, we register the bus with the kobject
799 * infrastructure, then register the children subsystems it has:
800 * the devices and drivers that belong to the subsystem.
801 */
802int bus_register(struct bus_type *bus)
803{
804 int retval;
805 struct subsys_private *priv;
806 struct lock_class_key *key = &bus->lock_key;
807
808 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
809 if (!priv)
810 return -ENOMEM;
811
812 priv->bus = bus;
813 bus->p = priv;
814
815 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
816
817 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
818 if (retval)
819 goto out;
820
821 priv->subsys.kobj.kset = bus_kset;
822 priv->subsys.kobj.ktype = &bus_ktype;
823 priv->drivers_autoprobe = 1;
824
825 retval = kset_register(&priv->subsys);
826 if (retval)
827 goto out;
828
829 retval = bus_create_file(bus, &bus_attr_uevent);
830 if (retval)
831 goto bus_uevent_fail;
832
833 priv->devices_kset = kset_create_and_add("devices", NULL,
834 &priv->subsys.kobj);
835 if (!priv->devices_kset) {
836 retval = -ENOMEM;
837 goto bus_devices_fail;
838 }
839
840 priv->drivers_kset = kset_create_and_add("drivers", NULL,
841 &priv->subsys.kobj);
842 if (!priv->drivers_kset) {
843 retval = -ENOMEM;
844 goto bus_drivers_fail;
845 }
846
847 INIT_LIST_HEAD(&priv->interfaces);
848 __mutex_init(&priv->mutex, "subsys mutex", key);
849 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
850 klist_init(&priv->klist_drivers, NULL, NULL);
851
852 retval = add_probe_files(bus);
853 if (retval)
854 goto bus_probe_files_fail;
855
856 retval = bus_add_groups(bus, bus->bus_groups);
857 if (retval)
858 goto bus_groups_fail;
859
860 pr_debug("bus: '%s': registered\n", bus->name);
861 return 0;
862
863bus_groups_fail:
864 remove_probe_files(bus);
865bus_probe_files_fail:
866 kset_unregister(bus->p->drivers_kset);
867bus_drivers_fail:
868 kset_unregister(bus->p->devices_kset);
869bus_devices_fail:
870 bus_remove_file(bus, &bus_attr_uevent);
871bus_uevent_fail:
872 kset_unregister(&bus->p->subsys);
873out:
874 kfree(bus->p);
875 bus->p = NULL;
876 return retval;
877}
878EXPORT_SYMBOL_GPL(bus_register);
879
880/**
881 * bus_unregister - remove a bus from the system
882 * @bus: bus.
883 *
884 * Unregister the child subsystems and the bus itself.
885 * Finally, we call bus_put() to release the refcount
886 */
887void bus_unregister(struct bus_type *bus)
888{
889 pr_debug("bus: '%s': unregistering\n", bus->name);
890 if (bus->dev_root)
891 device_unregister(bus->dev_root);
892 bus_remove_groups(bus, bus->bus_groups);
893 remove_probe_files(bus);
894 kset_unregister(bus->p->drivers_kset);
895 kset_unregister(bus->p->devices_kset);
896 bus_remove_file(bus, &bus_attr_uevent);
897 kset_unregister(&bus->p->subsys);
898}
899EXPORT_SYMBOL_GPL(bus_unregister);
900
901int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
902{
903 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
904}
905EXPORT_SYMBOL_GPL(bus_register_notifier);
906
907int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
908{
909 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
910}
911EXPORT_SYMBOL_GPL(bus_unregister_notifier);
912
913struct kset *bus_get_kset(struct bus_type *bus)
914{
915 return &bus->p->subsys;
916}
917EXPORT_SYMBOL_GPL(bus_get_kset);
918
919struct klist *bus_get_device_klist(struct bus_type *bus)
920{
921 return &bus->p->klist_devices;
922}
923EXPORT_SYMBOL_GPL(bus_get_device_klist);
924
925/*
926 * Yes, this forcibly breaks the klist abstraction temporarily. It
927 * just wants to sort the klist, not change reference counts and
928 * take/drop locks rapidly in the process. It does all this while
929 * holding the lock for the list, so objects can't otherwise be
930 * added/removed while we're swizzling.
931 */
932static void device_insertion_sort_klist(struct device *a, struct list_head *list,
933 int (*compare)(const struct device *a,
934 const struct device *b))
935{
936 struct klist_node *n;
937 struct device_private *dev_prv;
938 struct device *b;
939
940 list_for_each_entry(n, list, n_node) {
941 dev_prv = to_device_private_bus(n);
942 b = dev_prv->device;
943 if (compare(a, b) <= 0) {
944 list_move_tail(&a->p->knode_bus.n_node,
945 &b->p->knode_bus.n_node);
946 return;
947 }
948 }
949 list_move_tail(&a->p->knode_bus.n_node, list);
950}
951
952void bus_sort_breadthfirst(struct bus_type *bus,
953 int (*compare)(const struct device *a,
954 const struct device *b))
955{
956 LIST_HEAD(sorted_devices);
957 struct klist_node *n, *tmp;
958 struct device_private *dev_prv;
959 struct device *dev;
960 struct klist *device_klist;
961
962 device_klist = bus_get_device_klist(bus);
963
964 spin_lock(&device_klist->k_lock);
965 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
966 dev_prv = to_device_private_bus(n);
967 dev = dev_prv->device;
968 device_insertion_sort_klist(dev, &sorted_devices, compare);
969 }
970 list_splice(&sorted_devices, &device_klist->k_list);
971 spin_unlock(&device_klist->k_lock);
972}
973EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
974
975/**
976 * subsys_dev_iter_init - initialize subsys device iterator
977 * @iter: subsys iterator to initialize
978 * @subsys: the subsys we wanna iterate over
979 * @start: the device to start iterating from, if any
980 * @type: device_type of the devices to iterate over, NULL for all
981 *
982 * Initialize subsys iterator @iter such that it iterates over devices
983 * of @subsys. If @start is set, the list iteration will start there,
984 * otherwise if it is NULL, the iteration starts at the beginning of
985 * the list.
986 */
987void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
988 struct device *start, const struct device_type *type)
989{
990 struct klist_node *start_knode = NULL;
991
992 if (start)
993 start_knode = &start->p->knode_bus;
994 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
995 iter->type = type;
996}
997EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
998
999/**
1000 * subsys_dev_iter_next - iterate to the next device
1001 * @iter: subsys iterator to proceed
1002 *
1003 * Proceed @iter to the next device and return it. Returns NULL if
1004 * iteration is complete.
1005 *
1006 * The returned device is referenced and won't be released till
1007 * iterator is proceed to the next device or exited. The caller is
1008 * free to do whatever it wants to do with the device including
1009 * calling back into subsys code.
1010 */
1011struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1012{
1013 struct klist_node *knode;
1014 struct device *dev;
1015
1016 for (;;) {
1017 knode = klist_next(&iter->ki);
1018 if (!knode)
1019 return NULL;
1020 dev = to_device_private_bus(knode)->device;
1021 if (!iter->type || iter->type == dev->type)
1022 return dev;
1023 }
1024}
1025EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1026
1027/**
1028 * subsys_dev_iter_exit - finish iteration
1029 * @iter: subsys iterator to finish
1030 *
1031 * Finish an iteration. Always call this function after iteration is
1032 * complete whether the iteration ran till the end or not.
1033 */
1034void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1035{
1036 klist_iter_exit(&iter->ki);
1037}
1038EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1039
1040int subsys_interface_register(struct subsys_interface *sif)
1041{
1042 struct bus_type *subsys;
1043 struct subsys_dev_iter iter;
1044 struct device *dev;
1045
1046 if (!sif || !sif->subsys)
1047 return -ENODEV;
1048
1049 subsys = bus_get(sif->subsys);
1050 if (!subsys)
1051 return -EINVAL;
1052
1053 mutex_lock(&subsys->p->mutex);
1054 list_add_tail(&sif->node, &subsys->p->interfaces);
1055 if (sif->add_dev) {
1056 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1057 while ((dev = subsys_dev_iter_next(&iter)))
1058 sif->add_dev(dev, sif);
1059 subsys_dev_iter_exit(&iter);
1060 }
1061 mutex_unlock(&subsys->p->mutex);
1062
1063 return 0;
1064}
1065EXPORT_SYMBOL_GPL(subsys_interface_register);
1066
1067void subsys_interface_unregister(struct subsys_interface *sif)
1068{
1069 struct bus_type *subsys;
1070 struct subsys_dev_iter iter;
1071 struct device *dev;
1072
1073 if (!sif || !sif->subsys)
1074 return;
1075
1076 subsys = sif->subsys;
1077
1078 mutex_lock(&subsys->p->mutex);
1079 list_del_init(&sif->node);
1080 if (sif->remove_dev) {
1081 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1082 while ((dev = subsys_dev_iter_next(&iter)))
1083 sif->remove_dev(dev, sif);
1084 subsys_dev_iter_exit(&iter);
1085 }
1086 mutex_unlock(&subsys->p->mutex);
1087
1088 bus_put(subsys);
1089}
1090EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1091
1092static void system_root_device_release(struct device *dev)
1093{
1094 kfree(dev);
1095}
1096
1097static int subsys_register(struct bus_type *subsys,
1098 const struct attribute_group **groups,
1099 struct kobject *parent_of_root)
1100{
1101 struct device *dev;
1102 int err;
1103
1104 err = bus_register(subsys);
1105 if (err < 0)
1106 return err;
1107
1108 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1109 if (!dev) {
1110 err = -ENOMEM;
1111 goto err_dev;
1112 }
1113
1114 err = dev_set_name(dev, "%s", subsys->name);
1115 if (err < 0)
1116 goto err_name;
1117
1118 dev->kobj.parent = parent_of_root;
1119 dev->groups = groups;
1120 dev->release = system_root_device_release;
1121
1122 err = device_register(dev);
1123 if (err < 0)
1124 goto err_dev_reg;
1125
1126 subsys->dev_root = dev;
1127 return 0;
1128
1129err_dev_reg:
1130 put_device(dev);
1131 dev = NULL;
1132err_name:
1133 kfree(dev);
1134err_dev:
1135 bus_unregister(subsys);
1136 return err;
1137}
1138
1139/**
1140 * subsys_system_register - register a subsystem at /sys/devices/system/
1141 * @subsys: system subsystem
1142 * @groups: default attributes for the root device
1143 *
1144 * All 'system' subsystems have a /sys/devices/system/<name> root device
1145 * with the name of the subsystem. The root device can carry subsystem-
1146 * wide attributes. All registered devices are below this single root
1147 * device and are named after the subsystem with a simple enumeration
1148 * number appended. The registered devices are not explicitly named;
1149 * only 'id' in the device needs to be set.
1150 *
1151 * Do not use this interface for anything new, it exists for compatibility
1152 * with bad ideas only. New subsystems should use plain subsystems; and
1153 * add the subsystem-wide attributes should be added to the subsystem
1154 * directory itself and not some create fake root-device placed in
1155 * /sys/devices/system/<name>.
1156 */
1157int subsys_system_register(struct bus_type *subsys,
1158 const struct attribute_group **groups)
1159{
1160 return subsys_register(subsys, groups, &system_kset->kobj);
1161}
1162EXPORT_SYMBOL_GPL(subsys_system_register);
1163
1164/**
1165 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1166 * @subsys: virtual subsystem
1167 * @groups: default attributes for the root device
1168 *
1169 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1170 * with the name of the subystem. The root device can carry subsystem-wide
1171 * attributes. All registered devices are below this single root device.
1172 * There's no restriction on device naming. This is for kernel software
1173 * constructs which need sysfs interface.
1174 */
1175int subsys_virtual_register(struct bus_type *subsys,
1176 const struct attribute_group **groups)
1177{
1178 struct kobject *virtual_dir;
1179
1180 virtual_dir = virtual_device_parent(NULL);
1181 if (!virtual_dir)
1182 return -ENOMEM;
1183
1184 return subsys_register(subsys, groups, virtual_dir);
1185}
1186EXPORT_SYMBOL_GPL(subsys_virtual_register);
1187
1188int __init buses_init(void)
1189{
1190 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1191 if (!bus_kset)
1192 return -ENOMEM;
1193
1194 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1195 if (!system_kset)
1196 return -ENOMEM;
1197
1198 return 0;
1199}
1/*
2 * bus.c - bus driver management
3 *
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
6 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
7 * Copyright (c) 2007 Novell Inc.
8 *
9 * This file is released under the GPLv2
10 *
11 */
12
13#include <linux/device.h>
14#include <linux/module.h>
15#include <linux/errno.h>
16#include <linux/slab.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/mutex.h>
20#include "base.h"
21#include "power/power.h"
22
23/* /sys/devices/system */
24static struct kset *system_kset;
25
26#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
27
28/*
29 * sysfs bindings for drivers
30 */
31
32#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
33
34
35static int __must_check bus_rescan_devices_helper(struct device *dev,
36 void *data);
37
38static struct bus_type *bus_get(struct bus_type *bus)
39{
40 if (bus) {
41 kset_get(&bus->p->subsys);
42 return bus;
43 }
44 return NULL;
45}
46
47static void bus_put(struct bus_type *bus)
48{
49 if (bus)
50 kset_put(&bus->p->subsys);
51}
52
53static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
54 char *buf)
55{
56 struct driver_attribute *drv_attr = to_drv_attr(attr);
57 struct driver_private *drv_priv = to_driver(kobj);
58 ssize_t ret = -EIO;
59
60 if (drv_attr->show)
61 ret = drv_attr->show(drv_priv->driver, buf);
62 return ret;
63}
64
65static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
66 const char *buf, size_t count)
67{
68 struct driver_attribute *drv_attr = to_drv_attr(attr);
69 struct driver_private *drv_priv = to_driver(kobj);
70 ssize_t ret = -EIO;
71
72 if (drv_attr->store)
73 ret = drv_attr->store(drv_priv->driver, buf, count);
74 return ret;
75}
76
77static const struct sysfs_ops driver_sysfs_ops = {
78 .show = drv_attr_show,
79 .store = drv_attr_store,
80};
81
82static void driver_release(struct kobject *kobj)
83{
84 struct driver_private *drv_priv = to_driver(kobj);
85
86 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
87 kfree(drv_priv);
88}
89
90static struct kobj_type driver_ktype = {
91 .sysfs_ops = &driver_sysfs_ops,
92 .release = driver_release,
93};
94
95/*
96 * sysfs bindings for buses
97 */
98static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
99 char *buf)
100{
101 struct bus_attribute *bus_attr = to_bus_attr(attr);
102 struct subsys_private *subsys_priv = to_subsys_private(kobj);
103 ssize_t ret = 0;
104
105 if (bus_attr->show)
106 ret = bus_attr->show(subsys_priv->bus, buf);
107 return ret;
108}
109
110static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
111 const char *buf, size_t count)
112{
113 struct bus_attribute *bus_attr = to_bus_attr(attr);
114 struct subsys_private *subsys_priv = to_subsys_private(kobj);
115 ssize_t ret = 0;
116
117 if (bus_attr->store)
118 ret = bus_attr->store(subsys_priv->bus, buf, count);
119 return ret;
120}
121
122static const struct sysfs_ops bus_sysfs_ops = {
123 .show = bus_attr_show,
124 .store = bus_attr_store,
125};
126
127int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
128{
129 int error;
130 if (bus_get(bus)) {
131 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
132 bus_put(bus);
133 } else
134 error = -EINVAL;
135 return error;
136}
137EXPORT_SYMBOL_GPL(bus_create_file);
138
139void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
140{
141 if (bus_get(bus)) {
142 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
143 bus_put(bus);
144 }
145}
146EXPORT_SYMBOL_GPL(bus_remove_file);
147
148static struct kobj_type bus_ktype = {
149 .sysfs_ops = &bus_sysfs_ops,
150};
151
152static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
153{
154 struct kobj_type *ktype = get_ktype(kobj);
155
156 if (ktype == &bus_ktype)
157 return 1;
158 return 0;
159}
160
161static const struct kset_uevent_ops bus_uevent_ops = {
162 .filter = bus_uevent_filter,
163};
164
165static struct kset *bus_kset;
166
167
168#ifdef CONFIG_HOTPLUG
169/* Manually detach a device from its associated driver. */
170static ssize_t driver_unbind(struct device_driver *drv,
171 const char *buf, size_t count)
172{
173 struct bus_type *bus = bus_get(drv->bus);
174 struct device *dev;
175 int err = -ENODEV;
176
177 dev = bus_find_device_by_name(bus, NULL, buf);
178 if (dev && dev->driver == drv) {
179 if (dev->parent) /* Needed for USB */
180 device_lock(dev->parent);
181 device_release_driver(dev);
182 if (dev->parent)
183 device_unlock(dev->parent);
184 err = count;
185 }
186 put_device(dev);
187 bus_put(bus);
188 return err;
189}
190static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
191
192/*
193 * Manually attach a device to a driver.
194 * Note: the driver must want to bind to the device,
195 * it is not possible to override the driver's id table.
196 */
197static ssize_t driver_bind(struct device_driver *drv,
198 const char *buf, size_t count)
199{
200 struct bus_type *bus = bus_get(drv->bus);
201 struct device *dev;
202 int err = -ENODEV;
203
204 dev = bus_find_device_by_name(bus, NULL, buf);
205 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
206 if (dev->parent) /* Needed for USB */
207 device_lock(dev->parent);
208 device_lock(dev);
209 err = driver_probe_device(drv, dev);
210 device_unlock(dev);
211 if (dev->parent)
212 device_unlock(dev->parent);
213
214 if (err > 0) {
215 /* success */
216 err = count;
217 } else if (err == 0) {
218 /* driver didn't accept device */
219 err = -ENODEV;
220 }
221 }
222 put_device(dev);
223 bus_put(bus);
224 return err;
225}
226static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
227
228static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
229{
230 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
231}
232
233static ssize_t store_drivers_autoprobe(struct bus_type *bus,
234 const char *buf, size_t count)
235{
236 if (buf[0] == '0')
237 bus->p->drivers_autoprobe = 0;
238 else
239 bus->p->drivers_autoprobe = 1;
240 return count;
241}
242
243static ssize_t store_drivers_probe(struct bus_type *bus,
244 const char *buf, size_t count)
245{
246 struct device *dev;
247
248 dev = bus_find_device_by_name(bus, NULL, buf);
249 if (!dev)
250 return -ENODEV;
251 if (bus_rescan_devices_helper(dev, NULL) != 0)
252 return -EINVAL;
253 return count;
254}
255#endif
256
257static struct device *next_device(struct klist_iter *i)
258{
259 struct klist_node *n = klist_next(i);
260 struct device *dev = NULL;
261 struct device_private *dev_prv;
262
263 if (n) {
264 dev_prv = to_device_private_bus(n);
265 dev = dev_prv->device;
266 }
267 return dev;
268}
269
270/**
271 * bus_for_each_dev - device iterator.
272 * @bus: bus type.
273 * @start: device to start iterating from.
274 * @data: data for the callback.
275 * @fn: function to be called for each device.
276 *
277 * Iterate over @bus's list of devices, and call @fn for each,
278 * passing it @data. If @start is not NULL, we use that device to
279 * begin iterating from.
280 *
281 * We check the return of @fn each time. If it returns anything
282 * other than 0, we break out and return that value.
283 *
284 * NOTE: The device that returns a non-zero value is not retained
285 * in any way, nor is its refcount incremented. If the caller needs
286 * to retain this data, it should do so, and increment the reference
287 * count in the supplied callback.
288 */
289int bus_for_each_dev(struct bus_type *bus, struct device *start,
290 void *data, int (*fn)(struct device *, void *))
291{
292 struct klist_iter i;
293 struct device *dev;
294 int error = 0;
295
296 if (!bus)
297 return -EINVAL;
298
299 klist_iter_init_node(&bus->p->klist_devices, &i,
300 (start ? &start->p->knode_bus : NULL));
301 while ((dev = next_device(&i)) && !error)
302 error = fn(dev, data);
303 klist_iter_exit(&i);
304 return error;
305}
306EXPORT_SYMBOL_GPL(bus_for_each_dev);
307
308/**
309 * bus_find_device - device iterator for locating a particular device.
310 * @bus: bus type
311 * @start: Device to begin with
312 * @data: Data to pass to match function
313 * @match: Callback function to check device
314 *
315 * This is similar to the bus_for_each_dev() function above, but it
316 * returns a reference to a device that is 'found' for later use, as
317 * determined by the @match callback.
318 *
319 * The callback should return 0 if the device doesn't match and non-zero
320 * if it does. If the callback returns non-zero, this function will
321 * return to the caller and not iterate over any more devices.
322 */
323struct device *bus_find_device(struct bus_type *bus,
324 struct device *start, void *data,
325 int (*match)(struct device *dev, void *data))
326{
327 struct klist_iter i;
328 struct device *dev;
329
330 if (!bus)
331 return NULL;
332
333 klist_iter_init_node(&bus->p->klist_devices, &i,
334 (start ? &start->p->knode_bus : NULL));
335 while ((dev = next_device(&i)))
336 if (match(dev, data) && get_device(dev))
337 break;
338 klist_iter_exit(&i);
339 return dev;
340}
341EXPORT_SYMBOL_GPL(bus_find_device);
342
343static int match_name(struct device *dev, void *data)
344{
345 const char *name = data;
346
347 return sysfs_streq(name, dev_name(dev));
348}
349
350/**
351 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
352 * @bus: bus type
353 * @start: Device to begin with
354 * @name: name of the device to match
355 *
356 * This is similar to the bus_find_device() function above, but it handles
357 * searching by a name automatically, no need to write another strcmp matching
358 * function.
359 */
360struct device *bus_find_device_by_name(struct bus_type *bus,
361 struct device *start, const char *name)
362{
363 return bus_find_device(bus, start, (void *)name, match_name);
364}
365EXPORT_SYMBOL_GPL(bus_find_device_by_name);
366
367/**
368 * subsys_find_device_by_id - find a device with a specific enumeration number
369 * @subsys: subsystem
370 * @id: index 'id' in struct device
371 * @hint: device to check first
372 *
373 * Check the hint's next object and if it is a match return it directly,
374 * otherwise, fall back to a full list search. Either way a reference for
375 * the returned object is taken.
376 */
377struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
378 struct device *hint)
379{
380 struct klist_iter i;
381 struct device *dev;
382
383 if (!subsys)
384 return NULL;
385
386 if (hint) {
387 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
388 dev = next_device(&i);
389 if (dev && dev->id == id && get_device(dev)) {
390 klist_iter_exit(&i);
391 return dev;
392 }
393 klist_iter_exit(&i);
394 }
395
396 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
397 while ((dev = next_device(&i))) {
398 if (dev->id == id && get_device(dev)) {
399 klist_iter_exit(&i);
400 return dev;
401 }
402 }
403 klist_iter_exit(&i);
404 return NULL;
405}
406EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
407
408static struct device_driver *next_driver(struct klist_iter *i)
409{
410 struct klist_node *n = klist_next(i);
411 struct driver_private *drv_priv;
412
413 if (n) {
414 drv_priv = container_of(n, struct driver_private, knode_bus);
415 return drv_priv->driver;
416 }
417 return NULL;
418}
419
420/**
421 * bus_for_each_drv - driver iterator
422 * @bus: bus we're dealing with.
423 * @start: driver to start iterating on.
424 * @data: data to pass to the callback.
425 * @fn: function to call for each driver.
426 *
427 * This is nearly identical to the device iterator above.
428 * We iterate over each driver that belongs to @bus, and call
429 * @fn for each. If @fn returns anything but 0, we break out
430 * and return it. If @start is not NULL, we use it as the head
431 * of the list.
432 *
433 * NOTE: we don't return the driver that returns a non-zero
434 * value, nor do we leave the reference count incremented for that
435 * driver. If the caller needs to know that info, it must set it
436 * in the callback. It must also be sure to increment the refcount
437 * so it doesn't disappear before returning to the caller.
438 */
439int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
440 void *data, int (*fn)(struct device_driver *, void *))
441{
442 struct klist_iter i;
443 struct device_driver *drv;
444 int error = 0;
445
446 if (!bus)
447 return -EINVAL;
448
449 klist_iter_init_node(&bus->p->klist_drivers, &i,
450 start ? &start->p->knode_bus : NULL);
451 while ((drv = next_driver(&i)) && !error)
452 error = fn(drv, data);
453 klist_iter_exit(&i);
454 return error;
455}
456EXPORT_SYMBOL_GPL(bus_for_each_drv);
457
458static int device_add_attrs(struct bus_type *bus, struct device *dev)
459{
460 int error = 0;
461 int i;
462
463 if (!bus->dev_attrs)
464 return 0;
465
466 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
467 error = device_create_file(dev, &bus->dev_attrs[i]);
468 if (error) {
469 while (--i >= 0)
470 device_remove_file(dev, &bus->dev_attrs[i]);
471 break;
472 }
473 }
474 return error;
475}
476
477static void device_remove_attrs(struct bus_type *bus, struct device *dev)
478{
479 int i;
480
481 if (bus->dev_attrs) {
482 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
483 device_remove_file(dev, &bus->dev_attrs[i]);
484 }
485}
486
487/**
488 * bus_add_device - add device to bus
489 * @dev: device being added
490 *
491 * - Add device's bus attributes.
492 * - Create links to device's bus.
493 * - Add the device to its bus's list of devices.
494 */
495int bus_add_device(struct device *dev)
496{
497 struct bus_type *bus = bus_get(dev->bus);
498 int error = 0;
499
500 if (bus) {
501 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
502 error = device_add_attrs(bus, dev);
503 if (error)
504 goto out_put;
505 error = sysfs_create_link(&bus->p->devices_kset->kobj,
506 &dev->kobj, dev_name(dev));
507 if (error)
508 goto out_id;
509 error = sysfs_create_link(&dev->kobj,
510 &dev->bus->p->subsys.kobj, "subsystem");
511 if (error)
512 goto out_subsys;
513 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
514 }
515 return 0;
516
517out_subsys:
518 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
519out_id:
520 device_remove_attrs(bus, dev);
521out_put:
522 bus_put(dev->bus);
523 return error;
524}
525
526/**
527 * bus_probe_device - probe drivers for a new device
528 * @dev: device to probe
529 *
530 * - Automatically probe for a driver if the bus allows it.
531 */
532void bus_probe_device(struct device *dev)
533{
534 struct bus_type *bus = dev->bus;
535 struct subsys_interface *sif;
536 int ret;
537
538 if (!bus)
539 return;
540
541 if (bus->p->drivers_autoprobe) {
542 ret = device_attach(dev);
543 WARN_ON(ret < 0);
544 }
545
546 mutex_lock(&bus->p->mutex);
547 list_for_each_entry(sif, &bus->p->interfaces, node)
548 if (sif->add_dev)
549 sif->add_dev(dev, sif);
550 mutex_unlock(&bus->p->mutex);
551}
552
553/**
554 * bus_remove_device - remove device from bus
555 * @dev: device to be removed
556 *
557 * - Remove device from all interfaces.
558 * - Remove symlink from bus' directory.
559 * - Delete device from bus's list.
560 * - Detach from its driver.
561 * - Drop reference taken in bus_add_device().
562 */
563void bus_remove_device(struct device *dev)
564{
565 struct bus_type *bus = dev->bus;
566 struct subsys_interface *sif;
567
568 if (!bus)
569 return;
570
571 mutex_lock(&bus->p->mutex);
572 list_for_each_entry(sif, &bus->p->interfaces, node)
573 if (sif->remove_dev)
574 sif->remove_dev(dev, sif);
575 mutex_unlock(&bus->p->mutex);
576
577 sysfs_remove_link(&dev->kobj, "subsystem");
578 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
579 dev_name(dev));
580 device_remove_attrs(dev->bus, dev);
581 if (klist_node_attached(&dev->p->knode_bus))
582 klist_del(&dev->p->knode_bus);
583
584 pr_debug("bus: '%s': remove device %s\n",
585 dev->bus->name, dev_name(dev));
586 device_release_driver(dev);
587 bus_put(dev->bus);
588}
589
590static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
591{
592 int error = 0;
593 int i;
594
595 if (bus->drv_attrs) {
596 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
597 error = driver_create_file(drv, &bus->drv_attrs[i]);
598 if (error)
599 goto err;
600 }
601 }
602done:
603 return error;
604err:
605 while (--i >= 0)
606 driver_remove_file(drv, &bus->drv_attrs[i]);
607 goto done;
608}
609
610static void driver_remove_attrs(struct bus_type *bus,
611 struct device_driver *drv)
612{
613 int i;
614
615 if (bus->drv_attrs) {
616 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
617 driver_remove_file(drv, &bus->drv_attrs[i]);
618 }
619}
620
621#ifdef CONFIG_HOTPLUG
622/*
623 * Thanks to drivers making their tables __devinit, we can't allow manual
624 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
625 */
626static int __must_check add_bind_files(struct device_driver *drv)
627{
628 int ret;
629
630 ret = driver_create_file(drv, &driver_attr_unbind);
631 if (ret == 0) {
632 ret = driver_create_file(drv, &driver_attr_bind);
633 if (ret)
634 driver_remove_file(drv, &driver_attr_unbind);
635 }
636 return ret;
637}
638
639static void remove_bind_files(struct device_driver *drv)
640{
641 driver_remove_file(drv, &driver_attr_bind);
642 driver_remove_file(drv, &driver_attr_unbind);
643}
644
645static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
646static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
647 show_drivers_autoprobe, store_drivers_autoprobe);
648
649static int add_probe_files(struct bus_type *bus)
650{
651 int retval;
652
653 retval = bus_create_file(bus, &bus_attr_drivers_probe);
654 if (retval)
655 goto out;
656
657 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
658 if (retval)
659 bus_remove_file(bus, &bus_attr_drivers_probe);
660out:
661 return retval;
662}
663
664static void remove_probe_files(struct bus_type *bus)
665{
666 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
667 bus_remove_file(bus, &bus_attr_drivers_probe);
668}
669#else
670static inline int add_bind_files(struct device_driver *drv) { return 0; }
671static inline void remove_bind_files(struct device_driver *drv) {}
672static inline int add_probe_files(struct bus_type *bus) { return 0; }
673static inline void remove_probe_files(struct bus_type *bus) {}
674#endif
675
676static ssize_t driver_uevent_store(struct device_driver *drv,
677 const char *buf, size_t count)
678{
679 enum kobject_action action;
680
681 if (kobject_action_type(buf, count, &action) == 0)
682 kobject_uevent(&drv->p->kobj, action);
683 return count;
684}
685static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
686
687/**
688 * bus_add_driver - Add a driver to the bus.
689 * @drv: driver.
690 */
691int bus_add_driver(struct device_driver *drv)
692{
693 struct bus_type *bus;
694 struct driver_private *priv;
695 int error = 0;
696
697 bus = bus_get(drv->bus);
698 if (!bus)
699 return -EINVAL;
700
701 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
702
703 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
704 if (!priv) {
705 error = -ENOMEM;
706 goto out_put_bus;
707 }
708 klist_init(&priv->klist_devices, NULL, NULL);
709 priv->driver = drv;
710 drv->p = priv;
711 priv->kobj.kset = bus->p->drivers_kset;
712 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
713 "%s", drv->name);
714 if (error)
715 goto out_unregister;
716
717 if (drv->bus->p->drivers_autoprobe) {
718 error = driver_attach(drv);
719 if (error)
720 goto out_unregister;
721 }
722 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
723 module_add_driver(drv->owner, drv);
724
725 error = driver_create_file(drv, &driver_attr_uevent);
726 if (error) {
727 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
728 __func__, drv->name);
729 }
730 error = driver_add_attrs(bus, drv);
731 if (error) {
732 /* How the hell do we get out of this pickle? Give up */
733 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
734 __func__, drv->name);
735 }
736
737 if (!drv->suppress_bind_attrs) {
738 error = add_bind_files(drv);
739 if (error) {
740 /* Ditto */
741 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
742 __func__, drv->name);
743 }
744 }
745
746 kobject_uevent(&priv->kobj, KOBJ_ADD);
747 return 0;
748
749out_unregister:
750 kobject_put(&priv->kobj);
751 kfree(drv->p);
752 drv->p = NULL;
753out_put_bus:
754 bus_put(bus);
755 return error;
756}
757
758/**
759 * bus_remove_driver - delete driver from bus's knowledge.
760 * @drv: driver.
761 *
762 * Detach the driver from the devices it controls, and remove
763 * it from its bus's list of drivers. Finally, we drop the reference
764 * to the bus we took in bus_add_driver().
765 */
766void bus_remove_driver(struct device_driver *drv)
767{
768 if (!drv->bus)
769 return;
770
771 if (!drv->suppress_bind_attrs)
772 remove_bind_files(drv);
773 driver_remove_attrs(drv->bus, drv);
774 driver_remove_file(drv, &driver_attr_uevent);
775 klist_remove(&drv->p->knode_bus);
776 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
777 driver_detach(drv);
778 module_remove_driver(drv);
779 kobject_put(&drv->p->kobj);
780 bus_put(drv->bus);
781}
782
783/* Helper for bus_rescan_devices's iter */
784static int __must_check bus_rescan_devices_helper(struct device *dev,
785 void *data)
786{
787 int ret = 0;
788
789 if (!dev->driver) {
790 if (dev->parent) /* Needed for USB */
791 device_lock(dev->parent);
792 ret = device_attach(dev);
793 if (dev->parent)
794 device_unlock(dev->parent);
795 }
796 return ret < 0 ? ret : 0;
797}
798
799/**
800 * bus_rescan_devices - rescan devices on the bus for possible drivers
801 * @bus: the bus to scan.
802 *
803 * This function will look for devices on the bus with no driver
804 * attached and rescan it against existing drivers to see if it matches
805 * any by calling device_attach() for the unbound devices.
806 */
807int bus_rescan_devices(struct bus_type *bus)
808{
809 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
810}
811EXPORT_SYMBOL_GPL(bus_rescan_devices);
812
813/**
814 * device_reprobe - remove driver for a device and probe for a new driver
815 * @dev: the device to reprobe
816 *
817 * This function detaches the attached driver (if any) for the given
818 * device and restarts the driver probing process. It is intended
819 * to use if probing criteria changed during a devices lifetime and
820 * driver attachment should change accordingly.
821 */
822int device_reprobe(struct device *dev)
823{
824 if (dev->driver) {
825 if (dev->parent) /* Needed for USB */
826 device_lock(dev->parent);
827 device_release_driver(dev);
828 if (dev->parent)
829 device_unlock(dev->parent);
830 }
831 return bus_rescan_devices_helper(dev, NULL);
832}
833EXPORT_SYMBOL_GPL(device_reprobe);
834
835/**
836 * find_bus - locate bus by name.
837 * @name: name of bus.
838 *
839 * Call kset_find_obj() to iterate over list of buses to
840 * find a bus by name. Return bus if found.
841 *
842 * Note that kset_find_obj increments bus' reference count.
843 */
844#if 0
845struct bus_type *find_bus(char *name)
846{
847 struct kobject *k = kset_find_obj(bus_kset, name);
848 return k ? to_bus(k) : NULL;
849}
850#endif /* 0 */
851
852
853/**
854 * bus_add_attrs - Add default attributes for this bus.
855 * @bus: Bus that has just been registered.
856 */
857
858static int bus_add_attrs(struct bus_type *bus)
859{
860 int error = 0;
861 int i;
862
863 if (bus->bus_attrs) {
864 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
865 error = bus_create_file(bus, &bus->bus_attrs[i]);
866 if (error)
867 goto err;
868 }
869 }
870done:
871 return error;
872err:
873 while (--i >= 0)
874 bus_remove_file(bus, &bus->bus_attrs[i]);
875 goto done;
876}
877
878static void bus_remove_attrs(struct bus_type *bus)
879{
880 int i;
881
882 if (bus->bus_attrs) {
883 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
884 bus_remove_file(bus, &bus->bus_attrs[i]);
885 }
886}
887
888static void klist_devices_get(struct klist_node *n)
889{
890 struct device_private *dev_prv = to_device_private_bus(n);
891 struct device *dev = dev_prv->device;
892
893 get_device(dev);
894}
895
896static void klist_devices_put(struct klist_node *n)
897{
898 struct device_private *dev_prv = to_device_private_bus(n);
899 struct device *dev = dev_prv->device;
900
901 put_device(dev);
902}
903
904static ssize_t bus_uevent_store(struct bus_type *bus,
905 const char *buf, size_t count)
906{
907 enum kobject_action action;
908
909 if (kobject_action_type(buf, count, &action) == 0)
910 kobject_uevent(&bus->p->subsys.kobj, action);
911 return count;
912}
913static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
914
915/**
916 * __bus_register - register a driver-core subsystem
917 * @bus: bus to register
918 * @key: lockdep class key
919 *
920 * Once we have that, we register the bus with the kobject
921 * infrastructure, then register the children subsystems it has:
922 * the devices and drivers that belong to the subsystem.
923 */
924int __bus_register(struct bus_type *bus, struct lock_class_key *key)
925{
926 int retval;
927 struct subsys_private *priv;
928
929 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
930 if (!priv)
931 return -ENOMEM;
932
933 priv->bus = bus;
934 bus->p = priv;
935
936 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
937
938 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
939 if (retval)
940 goto out;
941
942 priv->subsys.kobj.kset = bus_kset;
943 priv->subsys.kobj.ktype = &bus_ktype;
944 priv->drivers_autoprobe = 1;
945
946 retval = kset_register(&priv->subsys);
947 if (retval)
948 goto out;
949
950 retval = bus_create_file(bus, &bus_attr_uevent);
951 if (retval)
952 goto bus_uevent_fail;
953
954 priv->devices_kset = kset_create_and_add("devices", NULL,
955 &priv->subsys.kobj);
956 if (!priv->devices_kset) {
957 retval = -ENOMEM;
958 goto bus_devices_fail;
959 }
960
961 priv->drivers_kset = kset_create_and_add("drivers", NULL,
962 &priv->subsys.kobj);
963 if (!priv->drivers_kset) {
964 retval = -ENOMEM;
965 goto bus_drivers_fail;
966 }
967
968 INIT_LIST_HEAD(&priv->interfaces);
969 __mutex_init(&priv->mutex, "subsys mutex", key);
970 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
971 klist_init(&priv->klist_drivers, NULL, NULL);
972
973 retval = add_probe_files(bus);
974 if (retval)
975 goto bus_probe_files_fail;
976
977 retval = bus_add_attrs(bus);
978 if (retval)
979 goto bus_attrs_fail;
980
981 pr_debug("bus: '%s': registered\n", bus->name);
982 return 0;
983
984bus_attrs_fail:
985 remove_probe_files(bus);
986bus_probe_files_fail:
987 kset_unregister(bus->p->drivers_kset);
988bus_drivers_fail:
989 kset_unregister(bus->p->devices_kset);
990bus_devices_fail:
991 bus_remove_file(bus, &bus_attr_uevent);
992bus_uevent_fail:
993 kset_unregister(&bus->p->subsys);
994out:
995 kfree(bus->p);
996 bus->p = NULL;
997 return retval;
998}
999EXPORT_SYMBOL_GPL(__bus_register);
1000
1001/**
1002 * bus_unregister - remove a bus from the system
1003 * @bus: bus.
1004 *
1005 * Unregister the child subsystems and the bus itself.
1006 * Finally, we call bus_put() to release the refcount
1007 */
1008void bus_unregister(struct bus_type *bus)
1009{
1010 pr_debug("bus: '%s': unregistering\n", bus->name);
1011 if (bus->dev_root)
1012 device_unregister(bus->dev_root);
1013 bus_remove_attrs(bus);
1014 remove_probe_files(bus);
1015 kset_unregister(bus->p->drivers_kset);
1016 kset_unregister(bus->p->devices_kset);
1017 bus_remove_file(bus, &bus_attr_uevent);
1018 kset_unregister(&bus->p->subsys);
1019 kfree(bus->p);
1020 bus->p = NULL;
1021}
1022EXPORT_SYMBOL_GPL(bus_unregister);
1023
1024int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
1025{
1026 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
1027}
1028EXPORT_SYMBOL_GPL(bus_register_notifier);
1029
1030int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
1031{
1032 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
1033}
1034EXPORT_SYMBOL_GPL(bus_unregister_notifier);
1035
1036struct kset *bus_get_kset(struct bus_type *bus)
1037{
1038 return &bus->p->subsys;
1039}
1040EXPORT_SYMBOL_GPL(bus_get_kset);
1041
1042struct klist *bus_get_device_klist(struct bus_type *bus)
1043{
1044 return &bus->p->klist_devices;
1045}
1046EXPORT_SYMBOL_GPL(bus_get_device_klist);
1047
1048/*
1049 * Yes, this forcibly breaks the klist abstraction temporarily. It
1050 * just wants to sort the klist, not change reference counts and
1051 * take/drop locks rapidly in the process. It does all this while
1052 * holding the lock for the list, so objects can't otherwise be
1053 * added/removed while we're swizzling.
1054 */
1055static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1056 int (*compare)(const struct device *a,
1057 const struct device *b))
1058{
1059 struct list_head *pos;
1060 struct klist_node *n;
1061 struct device_private *dev_prv;
1062 struct device *b;
1063
1064 list_for_each(pos, list) {
1065 n = container_of(pos, struct klist_node, n_node);
1066 dev_prv = to_device_private_bus(n);
1067 b = dev_prv->device;
1068 if (compare(a, b) <= 0) {
1069 list_move_tail(&a->p->knode_bus.n_node,
1070 &b->p->knode_bus.n_node);
1071 return;
1072 }
1073 }
1074 list_move_tail(&a->p->knode_bus.n_node, list);
1075}
1076
1077void bus_sort_breadthfirst(struct bus_type *bus,
1078 int (*compare)(const struct device *a,
1079 const struct device *b))
1080{
1081 LIST_HEAD(sorted_devices);
1082 struct list_head *pos, *tmp;
1083 struct klist_node *n;
1084 struct device_private *dev_prv;
1085 struct device *dev;
1086 struct klist *device_klist;
1087
1088 device_klist = bus_get_device_klist(bus);
1089
1090 spin_lock(&device_klist->k_lock);
1091 list_for_each_safe(pos, tmp, &device_klist->k_list) {
1092 n = container_of(pos, struct klist_node, n_node);
1093 dev_prv = to_device_private_bus(n);
1094 dev = dev_prv->device;
1095 device_insertion_sort_klist(dev, &sorted_devices, compare);
1096 }
1097 list_splice(&sorted_devices, &device_klist->k_list);
1098 spin_unlock(&device_klist->k_lock);
1099}
1100EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1101
1102/**
1103 * subsys_dev_iter_init - initialize subsys device iterator
1104 * @iter: subsys iterator to initialize
1105 * @subsys: the subsys we wanna iterate over
1106 * @start: the device to start iterating from, if any
1107 * @type: device_type of the devices to iterate over, NULL for all
1108 *
1109 * Initialize subsys iterator @iter such that it iterates over devices
1110 * of @subsys. If @start is set, the list iteration will start there,
1111 * otherwise if it is NULL, the iteration starts at the beginning of
1112 * the list.
1113 */
1114void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1115 struct device *start, const struct device_type *type)
1116{
1117 struct klist_node *start_knode = NULL;
1118
1119 if (start)
1120 start_knode = &start->p->knode_bus;
1121 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1122 iter->type = type;
1123}
1124EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1125
1126/**
1127 * subsys_dev_iter_next - iterate to the next device
1128 * @iter: subsys iterator to proceed
1129 *
1130 * Proceed @iter to the next device and return it. Returns NULL if
1131 * iteration is complete.
1132 *
1133 * The returned device is referenced and won't be released till
1134 * iterator is proceed to the next device or exited. The caller is
1135 * free to do whatever it wants to do with the device including
1136 * calling back into subsys code.
1137 */
1138struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1139{
1140 struct klist_node *knode;
1141 struct device *dev;
1142
1143 for (;;) {
1144 knode = klist_next(&iter->ki);
1145 if (!knode)
1146 return NULL;
1147 dev = container_of(knode, struct device_private, knode_bus)->device;
1148 if (!iter->type || iter->type == dev->type)
1149 return dev;
1150 }
1151}
1152EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1153
1154/**
1155 * subsys_dev_iter_exit - finish iteration
1156 * @iter: subsys iterator to finish
1157 *
1158 * Finish an iteration. Always call this function after iteration is
1159 * complete whether the iteration ran till the end or not.
1160 */
1161void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1162{
1163 klist_iter_exit(&iter->ki);
1164}
1165EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1166
1167int subsys_interface_register(struct subsys_interface *sif)
1168{
1169 struct bus_type *subsys;
1170 struct subsys_dev_iter iter;
1171 struct device *dev;
1172
1173 if (!sif || !sif->subsys)
1174 return -ENODEV;
1175
1176 subsys = bus_get(sif->subsys);
1177 if (!subsys)
1178 return -EINVAL;
1179
1180 mutex_lock(&subsys->p->mutex);
1181 list_add_tail(&sif->node, &subsys->p->interfaces);
1182 if (sif->add_dev) {
1183 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1184 while ((dev = subsys_dev_iter_next(&iter)))
1185 sif->add_dev(dev, sif);
1186 subsys_dev_iter_exit(&iter);
1187 }
1188 mutex_unlock(&subsys->p->mutex);
1189
1190 return 0;
1191}
1192EXPORT_SYMBOL_GPL(subsys_interface_register);
1193
1194void subsys_interface_unregister(struct subsys_interface *sif)
1195{
1196 struct bus_type *subsys;
1197 struct subsys_dev_iter iter;
1198 struct device *dev;
1199
1200 if (!sif || !sif->subsys)
1201 return;
1202
1203 subsys = sif->subsys;
1204
1205 mutex_lock(&subsys->p->mutex);
1206 list_del_init(&sif->node);
1207 if (sif->remove_dev) {
1208 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1209 while ((dev = subsys_dev_iter_next(&iter)))
1210 sif->remove_dev(dev, sif);
1211 subsys_dev_iter_exit(&iter);
1212 }
1213 mutex_unlock(&subsys->p->mutex);
1214
1215 bus_put(subsys);
1216}
1217EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1218
1219static void system_root_device_release(struct device *dev)
1220{
1221 kfree(dev);
1222}
1223/**
1224 * subsys_system_register - register a subsystem at /sys/devices/system/
1225 * @subsys: system subsystem
1226 * @groups: default attributes for the root device
1227 *
1228 * All 'system' subsystems have a /sys/devices/system/<name> root device
1229 * with the name of the subsystem. The root device can carry subsystem-
1230 * wide attributes. All registered devices are below this single root
1231 * device and are named after the subsystem with a simple enumeration
1232 * number appended. The registered devices are not explicitely named;
1233 * only 'id' in the device needs to be set.
1234 *
1235 * Do not use this interface for anything new, it exists for compatibility
1236 * with bad ideas only. New subsystems should use plain subsystems; and
1237 * add the subsystem-wide attributes should be added to the subsystem
1238 * directory itself and not some create fake root-device placed in
1239 * /sys/devices/system/<name>.
1240 */
1241int subsys_system_register(struct bus_type *subsys,
1242 const struct attribute_group **groups)
1243{
1244 struct device *dev;
1245 int err;
1246
1247 err = bus_register(subsys);
1248 if (err < 0)
1249 return err;
1250
1251 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1252 if (!dev) {
1253 err = -ENOMEM;
1254 goto err_dev;
1255 }
1256
1257 err = dev_set_name(dev, "%s", subsys->name);
1258 if (err < 0)
1259 goto err_name;
1260
1261 dev->kobj.parent = &system_kset->kobj;
1262 dev->groups = groups;
1263 dev->release = system_root_device_release;
1264
1265 err = device_register(dev);
1266 if (err < 0)
1267 goto err_dev_reg;
1268
1269 subsys->dev_root = dev;
1270 return 0;
1271
1272err_dev_reg:
1273 put_device(dev);
1274 dev = NULL;
1275err_name:
1276 kfree(dev);
1277err_dev:
1278 bus_unregister(subsys);
1279 return err;
1280}
1281EXPORT_SYMBOL_GPL(subsys_system_register);
1282
1283int __init buses_init(void)
1284{
1285 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1286 if (!bus_kset)
1287 return -ENOMEM;
1288
1289 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1290 if (!system_kset)
1291 return -ENOMEM;
1292
1293 return 0;
1294}