1 // SPDX-License-Identifier: GPL-2.0
3 * bus.c - bus driver management
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.
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>
22 #include "power/power.h"
24 /* /sys/devices/system */
25 static struct kset *system_kset;
27 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
30 * sysfs bindings for drivers
33 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
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)
39 static int __must_check bus_rescan_devices_helper(struct device *dev,
42 static struct bus_type *bus_get(struct bus_type *bus)
45 kset_get(&bus->p->subsys);
51 static void bus_put(struct bus_type *bus)
54 kset_put(&bus->p->subsys);
57 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
60 struct driver_attribute *drv_attr = to_drv_attr(attr);
61 struct driver_private *drv_priv = to_driver(kobj);
65 ret = drv_attr->show(drv_priv->driver, buf);
69 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
70 const char *buf, size_t count)
72 struct driver_attribute *drv_attr = to_drv_attr(attr);
73 struct driver_private *drv_priv = to_driver(kobj);
77 ret = drv_attr->store(drv_priv->driver, buf, count);
81 static const struct sysfs_ops driver_sysfs_ops = {
82 .show = drv_attr_show,
83 .store = drv_attr_store,
86 static void driver_release(struct kobject *kobj)
88 struct driver_private *drv_priv = to_driver(kobj);
90 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
94 static struct kobj_type driver_ktype = {
95 .sysfs_ops = &driver_sysfs_ops,
96 .release = driver_release,
100 * sysfs bindings for buses
102 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
105 struct bus_attribute *bus_attr = to_bus_attr(attr);
106 struct subsys_private *subsys_priv = to_subsys_private(kobj);
110 ret = bus_attr->show(subsys_priv->bus, buf);
114 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
115 const char *buf, size_t count)
117 struct bus_attribute *bus_attr = to_bus_attr(attr);
118 struct subsys_private *subsys_priv = to_subsys_private(kobj);
122 ret = bus_attr->store(subsys_priv->bus, buf, count);
126 static const struct sysfs_ops bus_sysfs_ops = {
127 .show = bus_attr_show,
128 .store = bus_attr_store,
131 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
135 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
141 EXPORT_SYMBOL_GPL(bus_create_file);
143 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
146 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
150 EXPORT_SYMBOL_GPL(bus_remove_file);
152 static void bus_release(struct kobject *kobj)
154 struct subsys_private *priv = to_subsys_private(kobj);
155 struct bus_type *bus = priv->bus;
161 static struct kobj_type bus_ktype = {
162 .sysfs_ops = &bus_sysfs_ops,
163 .release = bus_release,
166 static int bus_uevent_filter(const struct kobject *kobj)
168 const struct kobj_type *ktype = get_ktype(kobj);
170 if (ktype == &bus_ktype)
175 static const struct kset_uevent_ops bus_uevent_ops = {
176 .filter = bus_uevent_filter,
179 static struct kset *bus_kset;
181 /* Manually detach a device from its associated driver. */
182 static ssize_t unbind_store(struct device_driver *drv, const char *buf,
185 struct bus_type *bus = bus_get(drv->bus);
189 dev = bus_find_device_by_name(bus, NULL, buf);
190 if (dev && dev->driver == drv) {
191 device_driver_detach(dev);
198 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
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.
205 static ssize_t bind_store(struct device_driver *drv, const char *buf,
208 struct bus_type *bus = bus_get(drv->bus);
212 dev = bus_find_device_by_name(bus, NULL, buf);
213 if (dev && driver_match_device(drv, dev)) {
214 err = device_driver_attach(drv, dev);
224 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
226 static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
228 return sysfs_emit(buf, "%d\n", bus->p->drivers_autoprobe);
231 static ssize_t drivers_autoprobe_store(struct bus_type *bus,
232 const char *buf, size_t count)
235 bus->p->drivers_autoprobe = 0;
237 bus->p->drivers_autoprobe = 1;
241 static ssize_t drivers_probe_store(struct bus_type *bus,
242 const char *buf, size_t count)
247 dev = bus_find_device_by_name(bus, NULL, buf);
250 if (bus_rescan_devices_helper(dev, NULL) == 0)
256 static struct device *next_device(struct klist_iter *i)
258 struct klist_node *n = klist_next(i);
259 struct device *dev = NULL;
260 struct device_private *dev_prv;
263 dev_prv = to_device_private_bus(n);
264 dev = dev_prv->device;
270 * bus_for_each_dev - device iterator.
272 * @start: device to start iterating from.
273 * @data: data for the callback.
274 * @fn: function to be called for each device.
276 * Iterate over @bus's list of devices, and call @fn for each,
277 * passing it @data. If @start is not NULL, we use that device to
278 * begin iterating from.
280 * We check the return of @fn each time. If it returns anything
281 * other than 0, we break out and return that value.
283 * NOTE: The device that returns a non-zero value is not retained
284 * in any way, nor is its refcount incremented. If the caller needs
285 * to retain this data, it should do so, and increment the reference
286 * count in the supplied callback.
288 int bus_for_each_dev(struct bus_type *bus, struct device *start,
289 void *data, int (*fn)(struct device *, void *))
298 klist_iter_init_node(&bus->p->klist_devices, &i,
299 (start ? &start->p->knode_bus : NULL));
300 while (!error && (dev = next_device(&i)))
301 error = fn(dev, data);
305 EXPORT_SYMBOL_GPL(bus_for_each_dev);
308 * bus_find_device - device iterator for locating a particular device.
310 * @start: Device to begin with
311 * @data: Data to pass to match function
312 * @match: Callback function to check device
314 * This is similar to the bus_for_each_dev() function above, but it
315 * returns a reference to a device that is 'found' for later use, as
316 * determined by the @match callback.
318 * The callback should return 0 if the device doesn't match and non-zero
319 * if it does. If the callback returns non-zero, this function will
320 * return to the caller and not iterate over any more devices.
322 struct device *bus_find_device(struct bus_type *bus,
323 struct device *start, const void *data,
324 int (*match)(struct device *dev, const void *data))
332 klist_iter_init_node(&bus->p->klist_devices, &i,
333 (start ? &start->p->knode_bus : NULL));
334 while ((dev = next_device(&i)))
335 if (match(dev, data) && get_device(dev))
340 EXPORT_SYMBOL_GPL(bus_find_device);
342 static struct device_driver *next_driver(struct klist_iter *i)
344 struct klist_node *n = klist_next(i);
345 struct driver_private *drv_priv;
348 drv_priv = container_of(n, struct driver_private, knode_bus);
349 return drv_priv->driver;
355 * bus_for_each_drv - driver iterator
356 * @bus: bus we're dealing with.
357 * @start: driver to start iterating on.
358 * @data: data to pass to the callback.
359 * @fn: function to call for each driver.
361 * This is nearly identical to the device iterator above.
362 * We iterate over each driver that belongs to @bus, and call
363 * @fn for each. If @fn returns anything but 0, we break out
364 * and return it. If @start is not NULL, we use it as the head
367 * NOTE: we don't return the driver that returns a non-zero
368 * value, nor do we leave the reference count incremented for that
369 * driver. If the caller needs to know that info, it must set it
370 * in the callback. It must also be sure to increment the refcount
371 * so it doesn't disappear before returning to the caller.
373 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
374 void *data, int (*fn)(struct device_driver *, void *))
377 struct device_driver *drv;
383 klist_iter_init_node(&bus->p->klist_drivers, &i,
384 start ? &start->p->knode_bus : NULL);
385 while ((drv = next_driver(&i)) && !error)
386 error = fn(drv, data);
390 EXPORT_SYMBOL_GPL(bus_for_each_drv);
393 * bus_add_device - add device to bus
394 * @dev: device being added
396 * - Add device's bus attributes.
397 * - Create links to device's bus.
398 * - Add the device to its bus's list of devices.
400 int bus_add_device(struct device *dev)
402 struct bus_type *bus = bus_get(dev->bus);
406 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
407 error = device_add_groups(dev, bus->dev_groups);
410 error = sysfs_create_link(&bus->p->devices_kset->kobj,
411 &dev->kobj, dev_name(dev));
414 error = sysfs_create_link(&dev->kobj,
415 &dev->bus->p->subsys.kobj, "subsystem");
418 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
423 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
425 device_remove_groups(dev, bus->dev_groups);
432 * bus_probe_device - probe drivers for a new device
433 * @dev: device to probe
435 * - Automatically probe for a driver if the bus allows it.
437 void bus_probe_device(struct device *dev)
439 struct bus_type *bus = dev->bus;
440 struct subsys_interface *sif;
445 if (bus->p->drivers_autoprobe)
446 device_initial_probe(dev);
448 mutex_lock(&bus->p->mutex);
449 list_for_each_entry(sif, &bus->p->interfaces, node)
451 sif->add_dev(dev, sif);
452 mutex_unlock(&bus->p->mutex);
456 * bus_remove_device - remove device from bus
457 * @dev: device to be removed
459 * - Remove device from all interfaces.
460 * - Remove symlink from bus' directory.
461 * - Delete device from bus's list.
462 * - Detach from its driver.
463 * - Drop reference taken in bus_add_device().
465 void bus_remove_device(struct device *dev)
467 struct bus_type *bus = dev->bus;
468 struct subsys_interface *sif;
473 mutex_lock(&bus->p->mutex);
474 list_for_each_entry(sif, &bus->p->interfaces, node)
476 sif->remove_dev(dev, sif);
477 mutex_unlock(&bus->p->mutex);
479 sysfs_remove_link(&dev->kobj, "subsystem");
480 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
482 device_remove_groups(dev, dev->bus->dev_groups);
483 if (klist_node_attached(&dev->p->knode_bus))
484 klist_del(&dev->p->knode_bus);
486 pr_debug("bus: '%s': remove device %s\n",
487 dev->bus->name, dev_name(dev));
488 device_release_driver(dev);
492 static int __must_check add_bind_files(struct device_driver *drv)
496 ret = driver_create_file(drv, &driver_attr_unbind);
498 ret = driver_create_file(drv, &driver_attr_bind);
500 driver_remove_file(drv, &driver_attr_unbind);
505 static void remove_bind_files(struct device_driver *drv)
507 driver_remove_file(drv, &driver_attr_bind);
508 driver_remove_file(drv, &driver_attr_unbind);
511 static BUS_ATTR_WO(drivers_probe);
512 static BUS_ATTR_RW(drivers_autoprobe);
514 static int add_probe_files(struct bus_type *bus)
518 retval = bus_create_file(bus, &bus_attr_drivers_probe);
522 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
524 bus_remove_file(bus, &bus_attr_drivers_probe);
529 static void remove_probe_files(struct bus_type *bus)
531 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
532 bus_remove_file(bus, &bus_attr_drivers_probe);
535 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
540 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
541 return rc ? rc : count;
543 static DRIVER_ATTR_WO(uevent);
546 * bus_add_driver - Add a driver to the bus.
549 int bus_add_driver(struct device_driver *drv)
551 struct bus_type *bus;
552 struct driver_private *priv;
555 bus = bus_get(drv->bus);
559 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
561 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
566 klist_init(&priv->klist_devices, NULL, NULL);
569 priv->kobj.kset = bus->p->drivers_kset;
570 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
575 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
576 if (drv->bus->p->drivers_autoprobe) {
577 error = driver_attach(drv);
581 module_add_driver(drv->owner, drv);
583 error = driver_create_file(drv, &driver_attr_uevent);
585 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
586 __func__, drv->name);
588 error = driver_add_groups(drv, bus->drv_groups);
590 /* How the hell do we get out of this pickle? Give up */
591 printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
592 __func__, drv->name);
595 if (!drv->suppress_bind_attrs) {
596 error = add_bind_files(drv);
599 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
600 __func__, drv->name);
607 klist_del(&priv->knode_bus);
609 kobject_put(&priv->kobj);
610 /* drv->p is freed in driver_release() */
618 * bus_remove_driver - delete driver from bus's knowledge.
621 * Detach the driver from the devices it controls, and remove
622 * it from its bus's list of drivers. Finally, we drop the reference
623 * to the bus we took in bus_add_driver().
625 void bus_remove_driver(struct device_driver *drv)
630 if (!drv->suppress_bind_attrs)
631 remove_bind_files(drv);
632 driver_remove_groups(drv, drv->bus->drv_groups);
633 driver_remove_file(drv, &driver_attr_uevent);
634 klist_remove(&drv->p->knode_bus);
635 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
637 module_remove_driver(drv);
638 kobject_put(&drv->p->kobj);
642 /* Helper for bus_rescan_devices's iter */
643 static int __must_check bus_rescan_devices_helper(struct device *dev,
649 if (dev->parent && dev->bus->need_parent_lock)
650 device_lock(dev->parent);
651 ret = device_attach(dev);
652 if (dev->parent && dev->bus->need_parent_lock)
653 device_unlock(dev->parent);
655 return ret < 0 ? ret : 0;
659 * bus_rescan_devices - rescan devices on the bus for possible drivers
660 * @bus: the bus to scan.
662 * This function will look for devices on the bus with no driver
663 * attached and rescan it against existing drivers to see if it matches
664 * any by calling device_attach() for the unbound devices.
666 int bus_rescan_devices(struct bus_type *bus)
668 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
670 EXPORT_SYMBOL_GPL(bus_rescan_devices);
673 * device_reprobe - remove driver for a device and probe for a new driver
674 * @dev: the device to reprobe
676 * This function detaches the attached driver (if any) for the given
677 * device and restarts the driver probing process. It is intended
678 * to use if probing criteria changed during a devices lifetime and
679 * driver attachment should change accordingly.
681 int device_reprobe(struct device *dev)
684 device_driver_detach(dev);
685 return bus_rescan_devices_helper(dev, NULL);
687 EXPORT_SYMBOL_GPL(device_reprobe);
689 static int bus_add_groups(struct bus_type *bus,
690 const struct attribute_group **groups)
692 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
695 static void bus_remove_groups(struct bus_type *bus,
696 const struct attribute_group **groups)
698 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
701 static void klist_devices_get(struct klist_node *n)
703 struct device_private *dev_prv = to_device_private_bus(n);
704 struct device *dev = dev_prv->device;
709 static void klist_devices_put(struct klist_node *n)
711 struct device_private *dev_prv = to_device_private_bus(n);
712 struct device *dev = dev_prv->device;
717 static ssize_t bus_uevent_store(struct bus_type *bus,
718 const char *buf, size_t count)
722 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
723 return rc ? rc : count;
726 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
727 * here, but can not use it as earlier in the file we have
728 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
731 static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
735 * bus_register - register a driver-core subsystem
736 * @bus: bus to register
738 * Once we have that, we register the bus with the kobject
739 * infrastructure, then register the children subsystems it has:
740 * the devices and drivers that belong to the subsystem.
742 int bus_register(struct bus_type *bus)
745 struct subsys_private *priv;
746 struct lock_class_key *key = &bus->lock_key;
748 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
755 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
757 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
761 priv->subsys.kobj.kset = bus_kset;
762 priv->subsys.kobj.ktype = &bus_ktype;
763 priv->drivers_autoprobe = 1;
765 retval = kset_register(&priv->subsys);
769 retval = bus_create_file(bus, &bus_attr_uevent);
771 goto bus_uevent_fail;
773 priv->devices_kset = kset_create_and_add("devices", NULL,
775 if (!priv->devices_kset) {
777 goto bus_devices_fail;
780 priv->drivers_kset = kset_create_and_add("drivers", NULL,
782 if (!priv->drivers_kset) {
784 goto bus_drivers_fail;
787 INIT_LIST_HEAD(&priv->interfaces);
788 __mutex_init(&priv->mutex, "subsys mutex", key);
789 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
790 klist_init(&priv->klist_drivers, NULL, NULL);
792 retval = add_probe_files(bus);
794 goto bus_probe_files_fail;
796 retval = bus_add_groups(bus, bus->bus_groups);
798 goto bus_groups_fail;
800 pr_debug("bus: '%s': registered\n", bus->name);
804 remove_probe_files(bus);
805 bus_probe_files_fail:
806 kset_unregister(bus->p->drivers_kset);
808 kset_unregister(bus->p->devices_kset);
810 bus_remove_file(bus, &bus_attr_uevent);
812 kset_unregister(&bus->p->subsys);
818 EXPORT_SYMBOL_GPL(bus_register);
821 * bus_unregister - remove a bus from the system
824 * Unregister the child subsystems and the bus itself.
825 * Finally, we call bus_put() to release the refcount
827 void bus_unregister(struct bus_type *bus)
829 pr_debug("bus: '%s': unregistering\n", bus->name);
831 device_unregister(bus->dev_root);
832 bus_remove_groups(bus, bus->bus_groups);
833 remove_probe_files(bus);
834 kset_unregister(bus->p->drivers_kset);
835 kset_unregister(bus->p->devices_kset);
836 bus_remove_file(bus, &bus_attr_uevent);
837 kset_unregister(&bus->p->subsys);
839 EXPORT_SYMBOL_GPL(bus_unregister);
841 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
843 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
845 EXPORT_SYMBOL_GPL(bus_register_notifier);
847 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
849 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
851 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
853 struct kset *bus_get_kset(struct bus_type *bus)
855 return &bus->p->subsys;
857 EXPORT_SYMBOL_GPL(bus_get_kset);
859 static struct klist *bus_get_device_klist(struct bus_type *bus)
861 return &bus->p->klist_devices;
865 * Yes, this forcibly breaks the klist abstraction temporarily. It
866 * just wants to sort the klist, not change reference counts and
867 * take/drop locks rapidly in the process. It does all this while
868 * holding the lock for the list, so objects can't otherwise be
869 * added/removed while we're swizzling.
871 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
872 int (*compare)(const struct device *a,
873 const struct device *b))
875 struct klist_node *n;
876 struct device_private *dev_prv;
879 list_for_each_entry(n, list, n_node) {
880 dev_prv = to_device_private_bus(n);
882 if (compare(a, b) <= 0) {
883 list_move_tail(&a->p->knode_bus.n_node,
884 &b->p->knode_bus.n_node);
888 list_move_tail(&a->p->knode_bus.n_node, list);
891 void bus_sort_breadthfirst(struct bus_type *bus,
892 int (*compare)(const struct device *a,
893 const struct device *b))
895 LIST_HEAD(sorted_devices);
896 struct klist_node *n, *tmp;
897 struct device_private *dev_prv;
899 struct klist *device_klist;
901 device_klist = bus_get_device_klist(bus);
903 spin_lock(&device_klist->k_lock);
904 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
905 dev_prv = to_device_private_bus(n);
906 dev = dev_prv->device;
907 device_insertion_sort_klist(dev, &sorted_devices, compare);
909 list_splice(&sorted_devices, &device_klist->k_list);
910 spin_unlock(&device_klist->k_lock);
912 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
915 * subsys_dev_iter_init - initialize subsys device iterator
916 * @iter: subsys iterator to initialize
917 * @subsys: the subsys we wanna iterate over
918 * @start: the device to start iterating from, if any
919 * @type: device_type of the devices to iterate over, NULL for all
921 * Initialize subsys iterator @iter such that it iterates over devices
922 * of @subsys. If @start is set, the list iteration will start there,
923 * otherwise if it is NULL, the iteration starts at the beginning of
926 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
927 struct device *start, const struct device_type *type)
929 struct klist_node *start_knode = NULL;
932 start_knode = &start->p->knode_bus;
933 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
936 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
939 * subsys_dev_iter_next - iterate to the next device
940 * @iter: subsys iterator to proceed
942 * Proceed @iter to the next device and return it. Returns NULL if
943 * iteration is complete.
945 * The returned device is referenced and won't be released till
946 * iterator is proceed to the next device or exited. The caller is
947 * free to do whatever it wants to do with the device including
948 * calling back into subsys code.
950 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
952 struct klist_node *knode;
956 knode = klist_next(&iter->ki);
959 dev = to_device_private_bus(knode)->device;
960 if (!iter->type || iter->type == dev->type)
964 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
967 * subsys_dev_iter_exit - finish iteration
968 * @iter: subsys iterator to finish
970 * Finish an iteration. Always call this function after iteration is
971 * complete whether the iteration ran till the end or not.
973 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
975 klist_iter_exit(&iter->ki);
977 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
979 int subsys_interface_register(struct subsys_interface *sif)
981 struct bus_type *subsys;
982 struct subsys_dev_iter iter;
985 if (!sif || !sif->subsys)
988 subsys = bus_get(sif->subsys);
992 mutex_lock(&subsys->p->mutex);
993 list_add_tail(&sif->node, &subsys->p->interfaces);
995 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
996 while ((dev = subsys_dev_iter_next(&iter)))
997 sif->add_dev(dev, sif);
998 subsys_dev_iter_exit(&iter);
1000 mutex_unlock(&subsys->p->mutex);
1004 EXPORT_SYMBOL_GPL(subsys_interface_register);
1006 void subsys_interface_unregister(struct subsys_interface *sif)
1008 struct bus_type *subsys;
1009 struct subsys_dev_iter iter;
1012 if (!sif || !sif->subsys)
1015 subsys = sif->subsys;
1017 mutex_lock(&subsys->p->mutex);
1018 list_del_init(&sif->node);
1019 if (sif->remove_dev) {
1020 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1021 while ((dev = subsys_dev_iter_next(&iter)))
1022 sif->remove_dev(dev, sif);
1023 subsys_dev_iter_exit(&iter);
1025 mutex_unlock(&subsys->p->mutex);
1029 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1031 static void system_root_device_release(struct device *dev)
1036 static int subsys_register(struct bus_type *subsys,
1037 const struct attribute_group **groups,
1038 struct kobject *parent_of_root)
1043 err = bus_register(subsys);
1047 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1053 err = dev_set_name(dev, "%s", subsys->name);
1057 dev->kobj.parent = parent_of_root;
1058 dev->groups = groups;
1059 dev->release = system_root_device_release;
1061 err = device_register(dev);
1065 subsys->dev_root = dev;
1074 bus_unregister(subsys);
1079 * subsys_system_register - register a subsystem at /sys/devices/system/
1080 * @subsys: system subsystem
1081 * @groups: default attributes for the root device
1083 * All 'system' subsystems have a /sys/devices/system/<name> root device
1084 * with the name of the subsystem. The root device can carry subsystem-
1085 * wide attributes. All registered devices are below this single root
1086 * device and are named after the subsystem with a simple enumeration
1087 * number appended. The registered devices are not explicitly named;
1088 * only 'id' in the device needs to be set.
1090 * Do not use this interface for anything new, it exists for compatibility
1091 * with bad ideas only. New subsystems should use plain subsystems; and
1092 * add the subsystem-wide attributes should be added to the subsystem
1093 * directory itself and not some create fake root-device placed in
1094 * /sys/devices/system/<name>.
1096 int subsys_system_register(struct bus_type *subsys,
1097 const struct attribute_group **groups)
1099 return subsys_register(subsys, groups, &system_kset->kobj);
1101 EXPORT_SYMBOL_GPL(subsys_system_register);
1104 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1105 * @subsys: virtual subsystem
1106 * @groups: default attributes for the root device
1108 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1109 * with the name of the subystem. The root device can carry subsystem-wide
1110 * attributes. All registered devices are below this single root device.
1111 * There's no restriction on device naming. This is for kernel software
1112 * constructs which need sysfs interface.
1114 int subsys_virtual_register(struct bus_type *subsys,
1115 const struct attribute_group **groups)
1117 struct kobject *virtual_dir;
1119 virtual_dir = virtual_device_parent(NULL);
1123 return subsys_register(subsys, groups, virtual_dir);
1125 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1127 int __init buses_init(void)
1129 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1133 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);