2 * bus.c - bus driver management
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.
9 * This file is released under the GPLv2
13 #include <linux/async.h>
14 #include <linux/device.h>
15 #include <linux/module.h>
16 #include <linux/errno.h>
17 #include <linux/slab.h>
18 #include <linux/init.h>
19 #include <linux/string.h>
20 #include <linux/mutex.h>
21 #include <linux/sysfs.h>
23 #include "power/power.h"
25 /* /sys/devices/system */
26 static struct kset *system_kset;
28 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
31 * sysfs bindings for drivers
34 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
36 #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
37 struct driver_attribute driver_attr_##_name = \
38 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
40 static int __must_check bus_rescan_devices_helper(struct device *dev,
43 static struct bus_type *bus_get(struct bus_type *bus)
46 kset_get(&bus->p->subsys);
52 static void bus_put(struct bus_type *bus)
55 kset_put(&bus->p->subsys);
58 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
61 struct driver_attribute *drv_attr = to_drv_attr(attr);
62 struct driver_private *drv_priv = to_driver(kobj);
66 ret = drv_attr->show(drv_priv->driver, buf);
70 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
71 const char *buf, size_t count)
73 struct driver_attribute *drv_attr = to_drv_attr(attr);
74 struct driver_private *drv_priv = to_driver(kobj);
78 ret = drv_attr->store(drv_priv->driver, buf, count);
82 static const struct sysfs_ops driver_sysfs_ops = {
83 .show = drv_attr_show,
84 .store = drv_attr_store,
87 static void driver_release(struct kobject *kobj)
89 struct driver_private *drv_priv = to_driver(kobj);
91 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
95 static struct kobj_type driver_ktype = {
96 .sysfs_ops = &driver_sysfs_ops,
97 .release = driver_release,
101 * sysfs bindings for buses
103 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
106 struct bus_attribute *bus_attr = to_bus_attr(attr);
107 struct subsys_private *subsys_priv = to_subsys_private(kobj);
111 ret = bus_attr->show(subsys_priv->bus, buf);
115 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
116 const char *buf, size_t count)
118 struct bus_attribute *bus_attr = to_bus_attr(attr);
119 struct subsys_private *subsys_priv = to_subsys_private(kobj);
123 ret = bus_attr->store(subsys_priv->bus, buf, count);
127 static const struct sysfs_ops bus_sysfs_ops = {
128 .show = bus_attr_show,
129 .store = bus_attr_store,
132 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
136 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
142 EXPORT_SYMBOL_GPL(bus_create_file);
144 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
147 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
151 EXPORT_SYMBOL_GPL(bus_remove_file);
153 static void bus_release(struct kobject *kobj)
155 struct subsys_private *priv = to_subsys_private(kobj);
156 struct bus_type *bus = priv->bus;
162 static struct kobj_type bus_ktype = {
163 .sysfs_ops = &bus_sysfs_ops,
164 .release = bus_release,
167 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
169 struct kobj_type *ktype = get_ktype(kobj);
171 if (ktype == &bus_ktype)
176 static const struct kset_uevent_ops bus_uevent_ops = {
177 .filter = bus_uevent_filter,
180 static struct kset *bus_kset;
182 /* Manually detach a device from its associated driver. */
183 static ssize_t unbind_store(struct device_driver *drv, const char *buf,
186 struct bus_type *bus = bus_get(drv->bus);
190 dev = bus_find_device_by_name(bus, NULL, buf);
191 if (dev && dev->driver == drv) {
192 if (dev->parent) /* Needed for USB */
193 device_lock(dev->parent);
194 device_release_driver(dev);
196 device_unlock(dev->parent);
203 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
206 * Manually attach a device to a driver.
207 * Note: the driver must want to bind to the device,
208 * it is not possible to override the driver's id table.
210 static ssize_t bind_store(struct device_driver *drv, const char *buf,
213 struct bus_type *bus = bus_get(drv->bus);
217 dev = bus_find_device_by_name(bus, NULL, buf);
218 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
219 if (dev->parent) /* Needed for USB */
220 device_lock(dev->parent);
222 err = driver_probe_device(drv, dev);
225 device_unlock(dev->parent);
230 } else if (err == 0) {
231 /* driver didn't accept device */
239 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
241 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
243 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
246 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
247 const char *buf, size_t count)
250 bus->p->drivers_autoprobe = 0;
252 bus->p->drivers_autoprobe = 1;
256 static ssize_t store_drivers_probe(struct bus_type *bus,
257 const char *buf, size_t count)
262 dev = bus_find_device_by_name(bus, NULL, buf);
265 if (bus_rescan_devices_helper(dev, NULL) == 0)
271 static struct device *next_device(struct klist_iter *i)
273 struct klist_node *n = klist_next(i);
274 struct device *dev = NULL;
275 struct device_private *dev_prv;
278 dev_prv = to_device_private_bus(n);
279 dev = dev_prv->device;
285 * bus_for_each_dev - device iterator.
287 * @start: device to start iterating from.
288 * @data: data for the callback.
289 * @fn: function to be called for each device.
291 * Iterate over @bus's list of devices, and call @fn for each,
292 * passing it @data. If @start is not NULL, we use that device to
293 * begin iterating from.
295 * We check the return of @fn each time. If it returns anything
296 * other than 0, we break out and return that value.
298 * NOTE: The device that returns a non-zero value is not retained
299 * in any way, nor is its refcount incremented. If the caller needs
300 * to retain this data, it should do so, and increment the reference
301 * count in the supplied callback.
303 int bus_for_each_dev(struct bus_type *bus, struct device *start,
304 void *data, int (*fn)(struct device *, void *))
313 klist_iter_init_node(&bus->p->klist_devices, &i,
314 (start ? &start->p->knode_bus : NULL));
315 while ((dev = next_device(&i)) && !error)
316 error = fn(dev, data);
320 EXPORT_SYMBOL_GPL(bus_for_each_dev);
323 * bus_find_device - device iterator for locating a particular device.
325 * @start: Device to begin with
326 * @data: Data to pass to match function
327 * @match: Callback function to check device
329 * This is similar to the bus_for_each_dev() function above, but it
330 * returns a reference to a device that is 'found' for later use, as
331 * determined by the @match callback.
333 * The callback should return 0 if the device doesn't match and non-zero
334 * if it does. If the callback returns non-zero, this function will
335 * return to the caller and not iterate over any more devices.
337 struct device *bus_find_device(struct bus_type *bus,
338 struct device *start, void *data,
339 int (*match)(struct device *dev, void *data))
347 klist_iter_init_node(&bus->p->klist_devices, &i,
348 (start ? &start->p->knode_bus : NULL));
349 while ((dev = next_device(&i)))
350 if (match(dev, data) && get_device(dev))
355 EXPORT_SYMBOL_GPL(bus_find_device);
357 static int match_name(struct device *dev, void *data)
359 const char *name = data;
361 return sysfs_streq(name, dev_name(dev));
365 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
367 * @start: Device to begin with
368 * @name: name of the device to match
370 * This is similar to the bus_find_device() function above, but it handles
371 * searching by a name automatically, no need to write another strcmp matching
374 struct device *bus_find_device_by_name(struct bus_type *bus,
375 struct device *start, const char *name)
377 return bus_find_device(bus, start, (void *)name, match_name);
379 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
382 * subsys_find_device_by_id - find a device with a specific enumeration number
384 * @id: index 'id' in struct device
385 * @hint: device to check first
387 * Check the hint's next object and if it is a match return it directly,
388 * otherwise, fall back to a full list search. Either way a reference for
389 * the returned object is taken.
391 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
401 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
402 dev = next_device(&i);
403 if (dev && dev->id == id && get_device(dev)) {
410 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
411 while ((dev = next_device(&i))) {
412 if (dev->id == id && get_device(dev)) {
420 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
422 static struct device_driver *next_driver(struct klist_iter *i)
424 struct klist_node *n = klist_next(i);
425 struct driver_private *drv_priv;
428 drv_priv = container_of(n, struct driver_private, knode_bus);
429 return drv_priv->driver;
435 * bus_for_each_drv - driver iterator
436 * @bus: bus we're dealing with.
437 * @start: driver to start iterating on.
438 * @data: data to pass to the callback.
439 * @fn: function to call for each driver.
441 * This is nearly identical to the device iterator above.
442 * We iterate over each driver that belongs to @bus, and call
443 * @fn for each. If @fn returns anything but 0, we break out
444 * and return it. If @start is not NULL, we use it as the head
447 * NOTE: we don't return the driver that returns a non-zero
448 * value, nor do we leave the reference count incremented for that
449 * driver. If the caller needs to know that info, it must set it
450 * in the callback. It must also be sure to increment the refcount
451 * so it doesn't disappear before returning to the caller.
453 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
454 void *data, int (*fn)(struct device_driver *, void *))
457 struct device_driver *drv;
463 klist_iter_init_node(&bus->p->klist_drivers, &i,
464 start ? &start->p->knode_bus : NULL);
465 while ((drv = next_driver(&i)) && !error)
466 error = fn(drv, data);
470 EXPORT_SYMBOL_GPL(bus_for_each_drv);
473 * bus_add_device - add device to bus
474 * @dev: device being added
476 * - Add device's bus attributes.
477 * - Create links to device's bus.
478 * - Add the device to its bus's list of devices.
480 int bus_add_device(struct device *dev)
482 struct bus_type *bus = bus_get(dev->bus);
486 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
487 error = device_add_groups(dev, bus->dev_groups);
490 error = sysfs_create_link(&bus->p->devices_kset->kobj,
491 &dev->kobj, dev_name(dev));
494 error = sysfs_create_link(&dev->kobj,
495 &dev->bus->p->subsys.kobj, "subsystem");
498 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
503 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
505 device_remove_groups(dev, bus->dev_groups);
512 * bus_probe_device - probe drivers for a new device
513 * @dev: device to probe
515 * - Automatically probe for a driver if the bus allows it.
517 void bus_probe_device(struct device *dev)
519 struct bus_type *bus = dev->bus;
520 struct subsys_interface *sif;
525 if (bus->p->drivers_autoprobe)
526 device_initial_probe(dev);
528 mutex_lock(&bus->p->mutex);
529 list_for_each_entry(sif, &bus->p->interfaces, node)
531 sif->add_dev(dev, sif);
532 mutex_unlock(&bus->p->mutex);
536 * bus_remove_device - remove device from bus
537 * @dev: device to be removed
539 * - Remove device from all interfaces.
540 * - Remove symlink from bus' directory.
541 * - Delete device from bus's list.
542 * - Detach from its driver.
543 * - Drop reference taken in bus_add_device().
545 void bus_remove_device(struct device *dev)
547 struct bus_type *bus = dev->bus;
548 struct subsys_interface *sif;
553 mutex_lock(&bus->p->mutex);
554 list_for_each_entry(sif, &bus->p->interfaces, node)
556 sif->remove_dev(dev, sif);
557 mutex_unlock(&bus->p->mutex);
559 sysfs_remove_link(&dev->kobj, "subsystem");
560 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
562 device_remove_groups(dev, dev->bus->dev_groups);
563 if (klist_node_attached(&dev->p->knode_bus))
564 klist_del(&dev->p->knode_bus);
566 pr_debug("bus: '%s': remove device %s\n",
567 dev->bus->name, dev_name(dev));
568 device_release_driver(dev);
572 static int __must_check add_bind_files(struct device_driver *drv)
576 ret = driver_create_file(drv, &driver_attr_unbind);
578 ret = driver_create_file(drv, &driver_attr_bind);
580 driver_remove_file(drv, &driver_attr_unbind);
585 static void remove_bind_files(struct device_driver *drv)
587 driver_remove_file(drv, &driver_attr_bind);
588 driver_remove_file(drv, &driver_attr_unbind);
591 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
592 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
593 show_drivers_autoprobe, store_drivers_autoprobe);
595 static int add_probe_files(struct bus_type *bus)
599 retval = bus_create_file(bus, &bus_attr_drivers_probe);
603 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
605 bus_remove_file(bus, &bus_attr_drivers_probe);
610 static void remove_probe_files(struct bus_type *bus)
612 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
613 bus_remove_file(bus, &bus_attr_drivers_probe);
616 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
621 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
622 return rc ? rc : count;
624 static DRIVER_ATTR_WO(uevent);
626 static void driver_attach_async(void *_drv, async_cookie_t cookie)
628 struct device_driver *drv = _drv;
631 ret = driver_attach(drv);
633 pr_debug("bus: '%s': driver %s async attach completed: %d\n",
634 drv->bus->name, drv->name, ret);
638 * bus_add_driver - Add a driver to the bus.
641 int bus_add_driver(struct device_driver *drv)
643 struct bus_type *bus;
644 struct driver_private *priv;
647 bus = bus_get(drv->bus);
651 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
653 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
658 klist_init(&priv->klist_devices, NULL, NULL);
661 priv->kobj.kset = bus->p->drivers_kset;
662 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
667 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
668 if (drv->bus->p->drivers_autoprobe) {
669 if (driver_allows_async_probing(drv)) {
670 pr_debug("bus: '%s': probing driver %s asynchronously\n",
671 drv->bus->name, drv->name);
672 async_schedule(driver_attach_async, drv);
674 error = driver_attach(drv);
679 module_add_driver(drv->owner, drv);
681 error = driver_create_file(drv, &driver_attr_uevent);
683 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
684 __func__, drv->name);
686 error = driver_add_groups(drv, bus->drv_groups);
688 /* How the hell do we get out of this pickle? Give up */
689 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
690 __func__, drv->name);
693 if (!drv->suppress_bind_attrs) {
694 error = add_bind_files(drv);
697 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
698 __func__, drv->name);
705 kobject_put(&priv->kobj);
706 /* drv->p is freed in driver_release() */
714 * bus_remove_driver - delete driver from bus's knowledge.
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().
721 void bus_remove_driver(struct device_driver *drv)
726 if (!drv->suppress_bind_attrs)
727 remove_bind_files(drv);
728 driver_remove_groups(drv, drv->bus->drv_groups);
729 driver_remove_file(drv, &driver_attr_uevent);
730 klist_remove(&drv->p->knode_bus);
731 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
733 module_remove_driver(drv);
734 kobject_put(&drv->p->kobj);
738 /* Helper for bus_rescan_devices's iter */
739 static int __must_check bus_rescan_devices_helper(struct device *dev,
745 if (dev->parent) /* Needed for USB */
746 device_lock(dev->parent);
747 ret = device_attach(dev);
749 device_unlock(dev->parent);
751 return ret < 0 ? ret : 0;
755 * bus_rescan_devices - rescan devices on the bus for possible drivers
756 * @bus: the bus to scan.
758 * This function will look for devices on the bus with no driver
759 * attached and rescan it against existing drivers to see if it matches
760 * any by calling device_attach() for the unbound devices.
762 int bus_rescan_devices(struct bus_type *bus)
764 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
766 EXPORT_SYMBOL_GPL(bus_rescan_devices);
769 * device_reprobe - remove driver for a device and probe for a new driver
770 * @dev: the device to reprobe
772 * This function detaches the attached driver (if any) for the given
773 * device and restarts the driver probing process. It is intended
774 * to use if probing criteria changed during a devices lifetime and
775 * driver attachment should change accordingly.
777 int device_reprobe(struct device *dev)
780 if (dev->parent) /* Needed for USB */
781 device_lock(dev->parent);
782 device_release_driver(dev);
784 device_unlock(dev->parent);
786 return bus_rescan_devices_helper(dev, NULL);
788 EXPORT_SYMBOL_GPL(device_reprobe);
791 * find_bus - locate bus by name.
792 * @name: name of bus.
794 * Call kset_find_obj() to iterate over list of buses to
795 * find a bus by name. Return bus if found.
797 * Note that kset_find_obj increments bus' reference count.
800 struct bus_type *find_bus(char *name)
802 struct kobject *k = kset_find_obj(bus_kset, name);
803 return k ? to_bus(k) : NULL;
807 static int bus_add_groups(struct bus_type *bus,
808 const struct attribute_group **groups)
810 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
813 static void bus_remove_groups(struct bus_type *bus,
814 const struct attribute_group **groups)
816 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
819 static void klist_devices_get(struct klist_node *n)
821 struct device_private *dev_prv = to_device_private_bus(n);
822 struct device *dev = dev_prv->device;
827 static void klist_devices_put(struct klist_node *n)
829 struct device_private *dev_prv = to_device_private_bus(n);
830 struct device *dev = dev_prv->device;
835 static ssize_t bus_uevent_store(struct bus_type *bus,
836 const char *buf, size_t count)
840 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
841 return rc ? rc : count;
843 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
846 * bus_register - register a driver-core subsystem
847 * @bus: bus to register
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.
853 int bus_register(struct bus_type *bus)
856 struct subsys_private *priv;
857 struct lock_class_key *key = &bus->lock_key;
859 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
866 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
868 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
872 priv->subsys.kobj.kset = bus_kset;
873 priv->subsys.kobj.ktype = &bus_ktype;
874 priv->drivers_autoprobe = 1;
876 retval = kset_register(&priv->subsys);
880 retval = bus_create_file(bus, &bus_attr_uevent);
882 goto bus_uevent_fail;
884 priv->devices_kset = kset_create_and_add("devices", NULL,
886 if (!priv->devices_kset) {
888 goto bus_devices_fail;
891 priv->drivers_kset = kset_create_and_add("drivers", NULL,
893 if (!priv->drivers_kset) {
895 goto bus_drivers_fail;
898 INIT_LIST_HEAD(&priv->interfaces);
899 __mutex_init(&priv->mutex, "subsys mutex", key);
900 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
901 klist_init(&priv->klist_drivers, NULL, NULL);
903 retval = add_probe_files(bus);
905 goto bus_probe_files_fail;
907 retval = bus_add_groups(bus, bus->bus_groups);
909 goto bus_groups_fail;
911 pr_debug("bus: '%s': registered\n", bus->name);
915 remove_probe_files(bus);
916 bus_probe_files_fail:
917 kset_unregister(bus->p->drivers_kset);
919 kset_unregister(bus->p->devices_kset);
921 bus_remove_file(bus, &bus_attr_uevent);
923 kset_unregister(&bus->p->subsys);
929 EXPORT_SYMBOL_GPL(bus_register);
932 * bus_unregister - remove a bus from the system
935 * Unregister the child subsystems and the bus itself.
936 * Finally, we call bus_put() to release the refcount
938 void bus_unregister(struct bus_type *bus)
940 pr_debug("bus: '%s': unregistering\n", bus->name);
942 device_unregister(bus->dev_root);
943 bus_remove_groups(bus, bus->bus_groups);
944 remove_probe_files(bus);
945 kset_unregister(bus->p->drivers_kset);
946 kset_unregister(bus->p->devices_kset);
947 bus_remove_file(bus, &bus_attr_uevent);
948 kset_unregister(&bus->p->subsys);
950 EXPORT_SYMBOL_GPL(bus_unregister);
952 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
954 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
956 EXPORT_SYMBOL_GPL(bus_register_notifier);
958 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
960 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
962 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
964 struct kset *bus_get_kset(struct bus_type *bus)
966 return &bus->p->subsys;
968 EXPORT_SYMBOL_GPL(bus_get_kset);
970 struct klist *bus_get_device_klist(struct bus_type *bus)
972 return &bus->p->klist_devices;
974 EXPORT_SYMBOL_GPL(bus_get_device_klist);
977 * Yes, this forcibly breaks the klist abstraction temporarily. It
978 * just wants to sort the klist, not change reference counts and
979 * take/drop locks rapidly in the process. It does all this while
980 * holding the lock for the list, so objects can't otherwise be
981 * added/removed while we're swizzling.
983 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
984 int (*compare)(const struct device *a,
985 const struct device *b))
987 struct klist_node *n;
988 struct device_private *dev_prv;
991 list_for_each_entry(n, list, n_node) {
992 dev_prv = to_device_private_bus(n);
994 if (compare(a, b) <= 0) {
995 list_move_tail(&a->p->knode_bus.n_node,
996 &b->p->knode_bus.n_node);
1000 list_move_tail(&a->p->knode_bus.n_node, list);
1003 void bus_sort_breadthfirst(struct bus_type *bus,
1004 int (*compare)(const struct device *a,
1005 const struct device *b))
1007 LIST_HEAD(sorted_devices);
1008 struct klist_node *n, *tmp;
1009 struct device_private *dev_prv;
1011 struct klist *device_klist;
1013 device_klist = bus_get_device_klist(bus);
1015 spin_lock(&device_klist->k_lock);
1016 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1017 dev_prv = to_device_private_bus(n);
1018 dev = dev_prv->device;
1019 device_insertion_sort_klist(dev, &sorted_devices, compare);
1021 list_splice(&sorted_devices, &device_klist->k_list);
1022 spin_unlock(&device_klist->k_lock);
1024 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1027 * subsys_dev_iter_init - initialize subsys device iterator
1028 * @iter: subsys iterator to initialize
1029 * @subsys: the subsys we wanna iterate over
1030 * @start: the device to start iterating from, if any
1031 * @type: device_type of the devices to iterate over, NULL for all
1033 * Initialize subsys iterator @iter such that it iterates over devices
1034 * of @subsys. If @start is set, the list iteration will start there,
1035 * otherwise if it is NULL, the iteration starts at the beginning of
1038 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1039 struct device *start, const struct device_type *type)
1041 struct klist_node *start_knode = NULL;
1044 start_knode = &start->p->knode_bus;
1045 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1048 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1051 * subsys_dev_iter_next - iterate to the next device
1052 * @iter: subsys iterator to proceed
1054 * Proceed @iter to the next device and return it. Returns NULL if
1055 * iteration is complete.
1057 * The returned device is referenced and won't be released till
1058 * iterator is proceed to the next device or exited. The caller is
1059 * free to do whatever it wants to do with the device including
1060 * calling back into subsys code.
1062 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1064 struct klist_node *knode;
1068 knode = klist_next(&iter->ki);
1071 dev = to_device_private_bus(knode)->device;
1072 if (!iter->type || iter->type == dev->type)
1076 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1079 * subsys_dev_iter_exit - finish iteration
1080 * @iter: subsys iterator to finish
1082 * Finish an iteration. Always call this function after iteration is
1083 * complete whether the iteration ran till the end or not.
1085 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1087 klist_iter_exit(&iter->ki);
1089 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1091 int subsys_interface_register(struct subsys_interface *sif)
1093 struct bus_type *subsys;
1094 struct subsys_dev_iter iter;
1097 if (!sif || !sif->subsys)
1100 subsys = bus_get(sif->subsys);
1104 mutex_lock(&subsys->p->mutex);
1105 list_add_tail(&sif->node, &subsys->p->interfaces);
1107 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1108 while ((dev = subsys_dev_iter_next(&iter)))
1109 sif->add_dev(dev, sif);
1110 subsys_dev_iter_exit(&iter);
1112 mutex_unlock(&subsys->p->mutex);
1116 EXPORT_SYMBOL_GPL(subsys_interface_register);
1118 void subsys_interface_unregister(struct subsys_interface *sif)
1120 struct bus_type *subsys;
1121 struct subsys_dev_iter iter;
1124 if (!sif || !sif->subsys)
1127 subsys = sif->subsys;
1129 mutex_lock(&subsys->p->mutex);
1130 list_del_init(&sif->node);
1131 if (sif->remove_dev) {
1132 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1133 while ((dev = subsys_dev_iter_next(&iter)))
1134 sif->remove_dev(dev, sif);
1135 subsys_dev_iter_exit(&iter);
1137 mutex_unlock(&subsys->p->mutex);
1141 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1143 static void system_root_device_release(struct device *dev)
1148 static int subsys_register(struct bus_type *subsys,
1149 const struct attribute_group **groups,
1150 struct kobject *parent_of_root)
1155 err = bus_register(subsys);
1159 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1165 err = dev_set_name(dev, "%s", subsys->name);
1169 dev->kobj.parent = parent_of_root;
1170 dev->groups = groups;
1171 dev->release = system_root_device_release;
1173 err = device_register(dev);
1177 subsys->dev_root = dev;
1186 bus_unregister(subsys);
1191 * subsys_system_register - register a subsystem at /sys/devices/system/
1192 * @subsys: system subsystem
1193 * @groups: default attributes for the root device
1195 * All 'system' subsystems have a /sys/devices/system/<name> root device
1196 * with the name of the subsystem. The root device can carry subsystem-
1197 * wide attributes. All registered devices are below this single root
1198 * device and are named after the subsystem with a simple enumeration
1199 * number appended. The registered devices are not explicitly named;
1200 * only 'id' in the device needs to be set.
1202 * Do not use this interface for anything new, it exists for compatibility
1203 * with bad ideas only. New subsystems should use plain subsystems; and
1204 * add the subsystem-wide attributes should be added to the subsystem
1205 * directory itself and not some create fake root-device placed in
1206 * /sys/devices/system/<name>.
1208 int subsys_system_register(struct bus_type *subsys,
1209 const struct attribute_group **groups)
1211 return subsys_register(subsys, groups, &system_kset->kobj);
1213 EXPORT_SYMBOL_GPL(subsys_system_register);
1216 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1217 * @subsys: virtual subsystem
1218 * @groups: default attributes for the root device
1220 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1221 * with the name of the subystem. The root device can carry subsystem-wide
1222 * attributes. All registered devices are below this single root device.
1223 * There's no restriction on device naming. This is for kernel software
1224 * constructs which need sysfs interface.
1226 int subsys_virtual_register(struct bus_type *subsys,
1227 const struct attribute_group **groups)
1229 struct kobject *virtual_dir;
1231 virtual_dir = virtual_device_parent(NULL);
1235 return subsys_register(subsys, groups, virtual_dir);
1237 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1239 int __init buses_init(void)
1241 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1245 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);