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.h>
13 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/string.h>
18 #include <linux/mutex.h>
19 #include <linux/sysfs.h>
21 #include "power/power.h"
23 /* /sys/devices/system */
24 static struct kset *system_kset;
26 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
29 * sysfs bindings for drivers
32 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
34 #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
35 struct driver_attribute driver_attr_##_name = \
36 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
38 static int __must_check bus_rescan_devices_helper(struct device *dev,
41 static struct bus_type *bus_get(struct bus_type *bus)
44 kset_get(&bus->p->subsys);
50 static void bus_put(struct bus_type *bus)
53 kset_put(&bus->p->subsys);
56 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
59 struct driver_attribute *drv_attr = to_drv_attr(attr);
60 struct driver_private *drv_priv = to_driver(kobj);
64 ret = drv_attr->show(drv_priv->driver, buf);
68 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
69 const char *buf, size_t count)
71 struct driver_attribute *drv_attr = to_drv_attr(attr);
72 struct driver_private *drv_priv = to_driver(kobj);
76 ret = drv_attr->store(drv_priv->driver, buf, count);
80 static const struct sysfs_ops driver_sysfs_ops = {
81 .show = drv_attr_show,
82 .store = drv_attr_store,
85 static void driver_release(struct kobject *kobj)
87 struct driver_private *drv_priv = to_driver(kobj);
89 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
93 static struct kobj_type driver_ktype = {
94 .sysfs_ops = &driver_sysfs_ops,
95 .release = driver_release,
99 * sysfs bindings for buses
101 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
104 struct bus_attribute *bus_attr = to_bus_attr(attr);
105 struct subsys_private *subsys_priv = to_subsys_private(kobj);
109 ret = bus_attr->show(subsys_priv->bus, buf);
113 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
114 const char *buf, size_t count)
116 struct bus_attribute *bus_attr = to_bus_attr(attr);
117 struct subsys_private *subsys_priv = to_subsys_private(kobj);
121 ret = bus_attr->store(subsys_priv->bus, buf, count);
125 static const struct sysfs_ops bus_sysfs_ops = {
126 .show = bus_attr_show,
127 .store = bus_attr_store,
130 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
134 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
140 EXPORT_SYMBOL_GPL(bus_create_file);
142 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
145 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
149 EXPORT_SYMBOL_GPL(bus_remove_file);
151 static void bus_release(struct kobject *kobj)
153 struct subsys_private *priv = to_subsys_private(kobj);
154 struct bus_type *bus = priv->bus;
160 static struct kobj_type bus_ktype = {
161 .sysfs_ops = &bus_sysfs_ops,
162 .release = bus_release,
165 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
167 struct kobj_type *ktype = get_ktype(kobj);
169 if (ktype == &bus_ktype)
174 static const struct kset_uevent_ops bus_uevent_ops = {
175 .filter = bus_uevent_filter,
178 static struct kset *bus_kset;
180 /* Manually detach a device from its associated driver. */
181 static ssize_t unbind_store(struct device_driver *drv, const char *buf,
184 struct bus_type *bus = bus_get(drv->bus);
188 dev = bus_find_device_by_name(bus, NULL, buf);
189 if (dev && dev->driver == drv) {
190 device_driver_detach(dev);
197 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
200 * Manually attach a device to a driver.
201 * Note: the driver must want to bind to the device,
202 * it is not possible to override the driver's id table.
204 static ssize_t bind_store(struct device_driver *drv, const char *buf,
207 struct bus_type *bus = bus_get(drv->bus);
211 dev = bus_find_device_by_name(bus, NULL, buf);
212 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
213 err = device_driver_attach(drv, dev);
218 } else if (err == 0) {
219 /* driver didn't accept device */
227 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
229 static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
231 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
234 static ssize_t drivers_autoprobe_store(struct bus_type *bus,
235 const char *buf, size_t count)
238 bus->p->drivers_autoprobe = 0;
240 bus->p->drivers_autoprobe = 1;
244 static ssize_t drivers_probe_store(struct bus_type *bus,
245 const char *buf, size_t count)
250 dev = bus_find_device_by_name(bus, NULL, buf);
253 if (bus_rescan_devices_helper(dev, NULL) == 0)
259 static struct device *next_device(struct klist_iter *i)
261 struct klist_node *n = klist_next(i);
262 struct device *dev = NULL;
263 struct device_private *dev_prv;
266 dev_prv = to_device_private_bus(n);
267 dev = dev_prv->device;
273 * bus_for_each_dev - device iterator.
275 * @start: device to start iterating from.
276 * @data: data for the callback.
277 * @fn: function to be called for each device.
279 * Iterate over @bus's list of devices, and call @fn for each,
280 * passing it @data. If @start is not NULL, we use that device to
281 * begin iterating from.
283 * We check the return of @fn each time. If it returns anything
284 * other than 0, we break out and return that value.
286 * NOTE: The device that returns a non-zero value is not retained
287 * in any way, nor is its refcount incremented. If the caller needs
288 * to retain this data, it should do so, and increment the reference
289 * count in the supplied callback.
291 int bus_for_each_dev(struct bus_type *bus, struct device *start,
292 void *data, int (*fn)(struct device *, void *))
301 klist_iter_init_node(&bus->p->klist_devices, &i,
302 (start ? &start->p->knode_bus : NULL));
303 while (!error && (dev = next_device(&i)))
304 error = fn(dev, data);
308 EXPORT_SYMBOL_GPL(bus_for_each_dev);
311 * bus_find_device - device iterator for locating a particular device.
313 * @start: Device to begin with
314 * @data: Data to pass to match function
315 * @match: Callback function to check device
317 * This is similar to the bus_for_each_dev() function above, but it
318 * returns a reference to a device that is 'found' for later use, as
319 * determined by the @match callback.
321 * The callback should return 0 if the device doesn't match and non-zero
322 * if it does. If the callback returns non-zero, this function will
323 * return to the caller and not iterate over any more devices.
325 struct device *bus_find_device(struct bus_type *bus,
326 struct device *start, const void *data,
327 int (*match)(struct device *dev, const void *data))
335 klist_iter_init_node(&bus->p->klist_devices, &i,
336 (start ? &start->p->knode_bus : NULL));
337 while ((dev = next_device(&i)))
338 if (match(dev, data) && get_device(dev))
343 EXPORT_SYMBOL_GPL(bus_find_device);
346 * subsys_find_device_by_id - find a device with a specific enumeration number
348 * @id: index 'id' in struct device
349 * @hint: device to check first
351 * Check the hint's next object and if it is a match return it directly,
352 * otherwise, fall back to a full list search. Either way a reference for
353 * the returned object is taken.
355 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
365 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
366 dev = next_device(&i);
367 if (dev && dev->id == id && get_device(dev)) {
374 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
375 while ((dev = next_device(&i))) {
376 if (dev->id == id && get_device(dev)) {
384 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
386 static struct device_driver *next_driver(struct klist_iter *i)
388 struct klist_node *n = klist_next(i);
389 struct driver_private *drv_priv;
392 drv_priv = container_of(n, struct driver_private, knode_bus);
393 return drv_priv->driver;
399 * bus_for_each_drv - driver iterator
400 * @bus: bus we're dealing with.
401 * @start: driver to start iterating on.
402 * @data: data to pass to the callback.
403 * @fn: function to call for each driver.
405 * This is nearly identical to the device iterator above.
406 * We iterate over each driver that belongs to @bus, and call
407 * @fn for each. If @fn returns anything but 0, we break out
408 * and return it. If @start is not NULL, we use it as the head
411 * NOTE: we don't return the driver that returns a non-zero
412 * value, nor do we leave the reference count incremented for that
413 * driver. If the caller needs to know that info, it must set it
414 * in the callback. It must also be sure to increment the refcount
415 * so it doesn't disappear before returning to the caller.
417 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
418 void *data, int (*fn)(struct device_driver *, void *))
421 struct device_driver *drv;
427 klist_iter_init_node(&bus->p->klist_drivers, &i,
428 start ? &start->p->knode_bus : NULL);
429 while ((drv = next_driver(&i)) && !error)
430 error = fn(drv, data);
434 EXPORT_SYMBOL_GPL(bus_for_each_drv);
437 * bus_add_device - add device to bus
438 * @dev: device being added
440 * - Add device's bus attributes.
441 * - Create links to device's bus.
442 * - Add the device to its bus's list of devices.
444 int bus_add_device(struct device *dev)
446 struct bus_type *bus = bus_get(dev->bus);
450 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
451 error = device_add_groups(dev, bus->dev_groups);
454 error = sysfs_create_link(&bus->p->devices_kset->kobj,
455 &dev->kobj, dev_name(dev));
458 error = sysfs_create_link(&dev->kobj,
459 &dev->bus->p->subsys.kobj, "subsystem");
462 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
467 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
469 device_remove_groups(dev, bus->dev_groups);
476 * bus_probe_device - probe drivers for a new device
477 * @dev: device to probe
479 * - Automatically probe for a driver if the bus allows it.
481 void bus_probe_device(struct device *dev)
483 struct bus_type *bus = dev->bus;
484 struct subsys_interface *sif;
489 if (bus->p->drivers_autoprobe)
490 device_initial_probe(dev);
492 mutex_lock(&bus->p->mutex);
493 list_for_each_entry(sif, &bus->p->interfaces, node)
495 sif->add_dev(dev, sif);
496 mutex_unlock(&bus->p->mutex);
500 * bus_remove_device - remove device from bus
501 * @dev: device to be removed
503 * - Remove device from all interfaces.
504 * - Remove symlink from bus' directory.
505 * - Delete device from bus's list.
506 * - Detach from its driver.
507 * - Drop reference taken in bus_add_device().
509 void bus_remove_device(struct device *dev)
511 struct bus_type *bus = dev->bus;
512 struct subsys_interface *sif;
517 mutex_lock(&bus->p->mutex);
518 list_for_each_entry(sif, &bus->p->interfaces, node)
520 sif->remove_dev(dev, sif);
521 mutex_unlock(&bus->p->mutex);
523 sysfs_remove_link(&dev->kobj, "subsystem");
524 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
526 device_remove_groups(dev, dev->bus->dev_groups);
527 if (klist_node_attached(&dev->p->knode_bus))
528 klist_del(&dev->p->knode_bus);
530 pr_debug("bus: '%s': remove device %s\n",
531 dev->bus->name, dev_name(dev));
532 device_release_driver(dev);
536 static int __must_check add_bind_files(struct device_driver *drv)
540 ret = driver_create_file(drv, &driver_attr_unbind);
542 ret = driver_create_file(drv, &driver_attr_bind);
544 driver_remove_file(drv, &driver_attr_unbind);
549 static void remove_bind_files(struct device_driver *drv)
551 driver_remove_file(drv, &driver_attr_bind);
552 driver_remove_file(drv, &driver_attr_unbind);
555 static BUS_ATTR_WO(drivers_probe);
556 static BUS_ATTR_RW(drivers_autoprobe);
558 static int add_probe_files(struct bus_type *bus)
562 retval = bus_create_file(bus, &bus_attr_drivers_probe);
566 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
568 bus_remove_file(bus, &bus_attr_drivers_probe);
573 static void remove_probe_files(struct bus_type *bus)
575 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
576 bus_remove_file(bus, &bus_attr_drivers_probe);
579 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
584 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
585 return rc ? rc : count;
587 static DRIVER_ATTR_WO(uevent);
590 * bus_add_driver - Add a driver to the bus.
593 int bus_add_driver(struct device_driver *drv)
595 struct bus_type *bus;
596 struct driver_private *priv;
599 bus = bus_get(drv->bus);
603 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
605 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
610 klist_init(&priv->klist_devices, NULL, NULL);
613 priv->kobj.kset = bus->p->drivers_kset;
614 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
619 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
620 if (drv->bus->p->drivers_autoprobe) {
621 error = driver_attach(drv);
625 module_add_driver(drv->owner, drv);
627 error = driver_create_file(drv, &driver_attr_uevent);
629 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
630 __func__, drv->name);
632 error = driver_add_groups(drv, bus->drv_groups);
634 /* How the hell do we get out of this pickle? Give up */
635 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
636 __func__, drv->name);
639 if (!drv->suppress_bind_attrs) {
640 error = add_bind_files(drv);
643 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
644 __func__, drv->name);
651 klist_del(&priv->knode_bus);
653 kobject_put(&priv->kobj);
654 /* drv->p is freed in driver_release() */
662 * bus_remove_driver - delete driver from bus's knowledge.
665 * Detach the driver from the devices it controls, and remove
666 * it from its bus's list of drivers. Finally, we drop the reference
667 * to the bus we took in bus_add_driver().
669 void bus_remove_driver(struct device_driver *drv)
674 if (!drv->suppress_bind_attrs)
675 remove_bind_files(drv);
676 driver_remove_groups(drv, drv->bus->drv_groups);
677 driver_remove_file(drv, &driver_attr_uevent);
678 klist_remove(&drv->p->knode_bus);
679 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
681 module_remove_driver(drv);
682 kobject_put(&drv->p->kobj);
686 /* Helper for bus_rescan_devices's iter */
687 static int __must_check bus_rescan_devices_helper(struct device *dev,
693 if (dev->parent && dev->bus->need_parent_lock)
694 device_lock(dev->parent);
695 ret = device_attach(dev);
696 if (dev->parent && dev->bus->need_parent_lock)
697 device_unlock(dev->parent);
699 return ret < 0 ? ret : 0;
703 * bus_rescan_devices - rescan devices on the bus for possible drivers
704 * @bus: the bus to scan.
706 * This function will look for devices on the bus with no driver
707 * attached and rescan it against existing drivers to see if it matches
708 * any by calling device_attach() for the unbound devices.
710 int bus_rescan_devices(struct bus_type *bus)
712 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
714 EXPORT_SYMBOL_GPL(bus_rescan_devices);
717 * device_reprobe - remove driver for a device and probe for a new driver
718 * @dev: the device to reprobe
720 * This function detaches the attached driver (if any) for the given
721 * device and restarts the driver probing process. It is intended
722 * to use if probing criteria changed during a devices lifetime and
723 * driver attachment should change accordingly.
725 int device_reprobe(struct device *dev)
728 device_driver_detach(dev);
729 return bus_rescan_devices_helper(dev, NULL);
731 EXPORT_SYMBOL_GPL(device_reprobe);
734 * find_bus - locate bus by name.
735 * @name: name of bus.
737 * Call kset_find_obj() to iterate over list of buses to
738 * find a bus by name. Return bus if found.
740 * Note that kset_find_obj increments bus' reference count.
743 struct bus_type *find_bus(char *name)
745 struct kobject *k = kset_find_obj(bus_kset, name);
746 return k ? to_bus(k) : NULL;
750 static int bus_add_groups(struct bus_type *bus,
751 const struct attribute_group **groups)
753 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
756 static void bus_remove_groups(struct bus_type *bus,
757 const struct attribute_group **groups)
759 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
762 static void klist_devices_get(struct klist_node *n)
764 struct device_private *dev_prv = to_device_private_bus(n);
765 struct device *dev = dev_prv->device;
770 static void klist_devices_put(struct klist_node *n)
772 struct device_private *dev_prv = to_device_private_bus(n);
773 struct device *dev = dev_prv->device;
778 static ssize_t bus_uevent_store(struct bus_type *bus,
779 const char *buf, size_t count)
783 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
784 return rc ? rc : count;
787 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
788 * here, but can not use it as earlier in the file we have
789 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
792 static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
796 * bus_register - register a driver-core subsystem
797 * @bus: bus to register
799 * Once we have that, we register the bus with the kobject
800 * infrastructure, then register the children subsystems it has:
801 * the devices and drivers that belong to the subsystem.
803 int bus_register(struct bus_type *bus)
806 struct subsys_private *priv;
807 struct lock_class_key *key = &bus->lock_key;
809 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
816 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
818 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
822 priv->subsys.kobj.kset = bus_kset;
823 priv->subsys.kobj.ktype = &bus_ktype;
824 priv->drivers_autoprobe = 1;
826 retval = kset_register(&priv->subsys);
830 retval = bus_create_file(bus, &bus_attr_uevent);
832 goto bus_uevent_fail;
834 priv->devices_kset = kset_create_and_add("devices", NULL,
836 if (!priv->devices_kset) {
838 goto bus_devices_fail;
841 priv->drivers_kset = kset_create_and_add("drivers", NULL,
843 if (!priv->drivers_kset) {
845 goto bus_drivers_fail;
848 INIT_LIST_HEAD(&priv->interfaces);
849 __mutex_init(&priv->mutex, "subsys mutex", key);
850 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
851 klist_init(&priv->klist_drivers, NULL, NULL);
853 retval = add_probe_files(bus);
855 goto bus_probe_files_fail;
857 retval = bus_add_groups(bus, bus->bus_groups);
859 goto bus_groups_fail;
861 pr_debug("bus: '%s': registered\n", bus->name);
865 remove_probe_files(bus);
866 bus_probe_files_fail:
867 kset_unregister(bus->p->drivers_kset);
869 kset_unregister(bus->p->devices_kset);
871 bus_remove_file(bus, &bus_attr_uevent);
873 kset_unregister(&bus->p->subsys);
879 EXPORT_SYMBOL_GPL(bus_register);
882 * bus_unregister - remove a bus from the system
885 * Unregister the child subsystems and the bus itself.
886 * Finally, we call bus_put() to release the refcount
888 void bus_unregister(struct bus_type *bus)
890 pr_debug("bus: '%s': unregistering\n", bus->name);
892 device_unregister(bus->dev_root);
893 bus_remove_groups(bus, bus->bus_groups);
894 remove_probe_files(bus);
895 kset_unregister(bus->p->drivers_kset);
896 kset_unregister(bus->p->devices_kset);
897 bus_remove_file(bus, &bus_attr_uevent);
898 kset_unregister(&bus->p->subsys);
900 EXPORT_SYMBOL_GPL(bus_unregister);
902 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
904 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
906 EXPORT_SYMBOL_GPL(bus_register_notifier);
908 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
910 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
912 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
914 struct kset *bus_get_kset(struct bus_type *bus)
916 return &bus->p->subsys;
918 EXPORT_SYMBOL_GPL(bus_get_kset);
920 struct klist *bus_get_device_klist(struct bus_type *bus)
922 return &bus->p->klist_devices;
924 EXPORT_SYMBOL_GPL(bus_get_device_klist);
927 * Yes, this forcibly breaks the klist abstraction temporarily. It
928 * just wants to sort the klist, not change reference counts and
929 * take/drop locks rapidly in the process. It does all this while
930 * holding the lock for the list, so objects can't otherwise be
931 * added/removed while we're swizzling.
933 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
934 int (*compare)(const struct device *a,
935 const struct device *b))
937 struct klist_node *n;
938 struct device_private *dev_prv;
941 list_for_each_entry(n, list, n_node) {
942 dev_prv = to_device_private_bus(n);
944 if (compare(a, b) <= 0) {
945 list_move_tail(&a->p->knode_bus.n_node,
946 &b->p->knode_bus.n_node);
950 list_move_tail(&a->p->knode_bus.n_node, list);
953 void bus_sort_breadthfirst(struct bus_type *bus,
954 int (*compare)(const struct device *a,
955 const struct device *b))
957 LIST_HEAD(sorted_devices);
958 struct klist_node *n, *tmp;
959 struct device_private *dev_prv;
961 struct klist *device_klist;
963 device_klist = bus_get_device_klist(bus);
965 spin_lock(&device_klist->k_lock);
966 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
967 dev_prv = to_device_private_bus(n);
968 dev = dev_prv->device;
969 device_insertion_sort_klist(dev, &sorted_devices, compare);
971 list_splice(&sorted_devices, &device_klist->k_list);
972 spin_unlock(&device_klist->k_lock);
974 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
977 * subsys_dev_iter_init - initialize subsys device iterator
978 * @iter: subsys iterator to initialize
979 * @subsys: the subsys we wanna iterate over
980 * @start: the device to start iterating from, if any
981 * @type: device_type of the devices to iterate over, NULL for all
983 * Initialize subsys iterator @iter such that it iterates over devices
984 * of @subsys. If @start is set, the list iteration will start there,
985 * otherwise if it is NULL, the iteration starts at the beginning of
988 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
989 struct device *start, const struct device_type *type)
991 struct klist_node *start_knode = NULL;
994 start_knode = &start->p->knode_bus;
995 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
998 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1001 * subsys_dev_iter_next - iterate to the next device
1002 * @iter: subsys iterator to proceed
1004 * Proceed @iter to the next device and return it. Returns NULL if
1005 * iteration is complete.
1007 * The returned device is referenced and won't be released till
1008 * iterator is proceed to the next device or exited. The caller is
1009 * free to do whatever it wants to do with the device including
1010 * calling back into subsys code.
1012 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1014 struct klist_node *knode;
1018 knode = klist_next(&iter->ki);
1021 dev = to_device_private_bus(knode)->device;
1022 if (!iter->type || iter->type == dev->type)
1026 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1029 * subsys_dev_iter_exit - finish iteration
1030 * @iter: subsys iterator to finish
1032 * Finish an iteration. Always call this function after iteration is
1033 * complete whether the iteration ran till the end or not.
1035 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1037 klist_iter_exit(&iter->ki);
1039 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1041 int subsys_interface_register(struct subsys_interface *sif)
1043 struct bus_type *subsys;
1044 struct subsys_dev_iter iter;
1047 if (!sif || !sif->subsys)
1050 subsys = bus_get(sif->subsys);
1054 mutex_lock(&subsys->p->mutex);
1055 list_add_tail(&sif->node, &subsys->p->interfaces);
1057 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1058 while ((dev = subsys_dev_iter_next(&iter)))
1059 sif->add_dev(dev, sif);
1060 subsys_dev_iter_exit(&iter);
1062 mutex_unlock(&subsys->p->mutex);
1066 EXPORT_SYMBOL_GPL(subsys_interface_register);
1068 void subsys_interface_unregister(struct subsys_interface *sif)
1070 struct bus_type *subsys;
1071 struct subsys_dev_iter iter;
1074 if (!sif || !sif->subsys)
1077 subsys = sif->subsys;
1079 mutex_lock(&subsys->p->mutex);
1080 list_del_init(&sif->node);
1081 if (sif->remove_dev) {
1082 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1083 while ((dev = subsys_dev_iter_next(&iter)))
1084 sif->remove_dev(dev, sif);
1085 subsys_dev_iter_exit(&iter);
1087 mutex_unlock(&subsys->p->mutex);
1091 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1093 static void system_root_device_release(struct device *dev)
1098 static int subsys_register(struct bus_type *subsys,
1099 const struct attribute_group **groups,
1100 struct kobject *parent_of_root)
1105 err = bus_register(subsys);
1109 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1115 err = dev_set_name(dev, "%s", subsys->name);
1119 dev->kobj.parent = parent_of_root;
1120 dev->groups = groups;
1121 dev->release = system_root_device_release;
1123 err = device_register(dev);
1127 subsys->dev_root = dev;
1136 bus_unregister(subsys);
1141 * subsys_system_register - register a subsystem at /sys/devices/system/
1142 * @subsys: system subsystem
1143 * @groups: default attributes for the root device
1145 * All 'system' subsystems have a /sys/devices/system/<name> root device
1146 * with the name of the subsystem. The root device can carry subsystem-
1147 * wide attributes. All registered devices are below this single root
1148 * device and are named after the subsystem with a simple enumeration
1149 * number appended. The registered devices are not explicitly named;
1150 * only 'id' in the device needs to be set.
1152 * Do not use this interface for anything new, it exists for compatibility
1153 * with bad ideas only. New subsystems should use plain subsystems; and
1154 * add the subsystem-wide attributes should be added to the subsystem
1155 * directory itself and not some create fake root-device placed in
1156 * /sys/devices/system/<name>.
1158 int subsys_system_register(struct bus_type *subsys,
1159 const struct attribute_group **groups)
1161 return subsys_register(subsys, groups, &system_kset->kobj);
1163 EXPORT_SYMBOL_GPL(subsys_system_register);
1166 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1167 * @subsys: virtual subsystem
1168 * @groups: default attributes for the root device
1170 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1171 * with the name of the subystem. The root device can carry subsystem-wide
1172 * attributes. All registered devices are below this single root device.
1173 * There's no restriction on device naming. This is for kernel software
1174 * constructs which need sysfs interface.
1176 int subsys_virtual_register(struct bus_type *subsys,
1177 const struct attribute_group **groups)
1179 struct kobject *virtual_dir;
1181 virtual_dir = virtual_device_parent(NULL);
1185 return subsys_register(subsys, groups, virtual_dir);
1187 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1189 int __init buses_init(void)
1191 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1195 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);