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 if (dev->parent && dev->bus->need_parent_lock)
191 device_lock(dev->parent);
192 device_release_driver(dev);
193 if (dev->parent && dev->bus->need_parent_lock)
194 device_unlock(dev->parent);
201 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, S_IWUSR, NULL, unbind_store);
204 * Manually attach a device to a driver.
205 * Note: the driver must want to bind to the device,
206 * it is not possible to override the driver's id table.
208 static ssize_t bind_store(struct device_driver *drv, const char *buf,
211 struct bus_type *bus = bus_get(drv->bus);
215 dev = bus_find_device_by_name(bus, NULL, buf);
216 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
217 if (dev->parent && bus->need_parent_lock)
218 device_lock(dev->parent);
220 err = driver_probe_device(drv, dev);
222 if (dev->parent && bus->need_parent_lock)
223 device_unlock(dev->parent);
228 } else if (err == 0) {
229 /* driver didn't accept device */
237 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
239 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
241 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
244 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
245 const char *buf, size_t count)
248 bus->p->drivers_autoprobe = 0;
250 bus->p->drivers_autoprobe = 1;
254 static ssize_t store_drivers_probe(struct bus_type *bus,
255 const char *buf, size_t count)
260 dev = bus_find_device_by_name(bus, NULL, buf);
263 if (bus_rescan_devices_helper(dev, NULL) == 0)
269 static struct device *next_device(struct klist_iter *i)
271 struct klist_node *n = klist_next(i);
272 struct device *dev = NULL;
273 struct device_private *dev_prv;
276 dev_prv = to_device_private_bus(n);
277 dev = dev_prv->device;
283 * bus_for_each_dev - device iterator.
285 * @start: device to start iterating from.
286 * @data: data for the callback.
287 * @fn: function to be called for each device.
289 * Iterate over @bus's list of devices, and call @fn for each,
290 * passing it @data. If @start is not NULL, we use that device to
291 * begin iterating from.
293 * We check the return of @fn each time. If it returns anything
294 * other than 0, we break out and return that value.
296 * NOTE: The device that returns a non-zero value is not retained
297 * in any way, nor is its refcount incremented. If the caller needs
298 * to retain this data, it should do so, and increment the reference
299 * count in the supplied callback.
301 int bus_for_each_dev(struct bus_type *bus, struct device *start,
302 void *data, int (*fn)(struct device *, void *))
311 klist_iter_init_node(&bus->p->klist_devices, &i,
312 (start ? &start->p->knode_bus : NULL));
313 while (!error && (dev = next_device(&i)))
314 error = fn(dev, data);
318 EXPORT_SYMBOL_GPL(bus_for_each_dev);
321 * bus_find_device - device iterator for locating a particular device.
323 * @start: Device to begin with
324 * @data: Data to pass to match function
325 * @match: Callback function to check device
327 * This is similar to the bus_for_each_dev() function above, but it
328 * returns a reference to a device that is 'found' for later use, as
329 * determined by the @match callback.
331 * The callback should return 0 if the device doesn't match and non-zero
332 * if it does. If the callback returns non-zero, this function will
333 * return to the caller and not iterate over any more devices.
335 struct device *bus_find_device(struct bus_type *bus,
336 struct device *start, void *data,
337 int (*match)(struct device *dev, void *data))
345 klist_iter_init_node(&bus->p->klist_devices, &i,
346 (start ? &start->p->knode_bus : NULL));
347 while ((dev = next_device(&i)))
348 if (match(dev, data) && get_device(dev))
353 EXPORT_SYMBOL_GPL(bus_find_device);
355 static int match_name(struct device *dev, void *data)
357 const char *name = data;
359 return sysfs_streq(name, dev_name(dev));
363 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
365 * @start: Device to begin with
366 * @name: name of the device to match
368 * This is similar to the bus_find_device() function above, but it handles
369 * searching by a name automatically, no need to write another strcmp matching
372 struct device *bus_find_device_by_name(struct bus_type *bus,
373 struct device *start, const char *name)
375 return bus_find_device(bus, start, (void *)name, match_name);
377 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
380 * subsys_find_device_by_id - find a device with a specific enumeration number
382 * @id: index 'id' in struct device
383 * @hint: device to check first
385 * Check the hint's next object and if it is a match return it directly,
386 * otherwise, fall back to a full list search. Either way a reference for
387 * the returned object is taken.
389 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
399 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
400 dev = next_device(&i);
401 if (dev && dev->id == id && get_device(dev)) {
408 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
409 while ((dev = next_device(&i))) {
410 if (dev->id == id && get_device(dev)) {
418 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
420 static struct device_driver *next_driver(struct klist_iter *i)
422 struct klist_node *n = klist_next(i);
423 struct driver_private *drv_priv;
426 drv_priv = container_of(n, struct driver_private, knode_bus);
427 return drv_priv->driver;
433 * bus_for_each_drv - driver iterator
434 * @bus: bus we're dealing with.
435 * @start: driver to start iterating on.
436 * @data: data to pass to the callback.
437 * @fn: function to call for each driver.
439 * This is nearly identical to the device iterator above.
440 * We iterate over each driver that belongs to @bus, and call
441 * @fn for each. If @fn returns anything but 0, we break out
442 * and return it. If @start is not NULL, we use it as the head
445 * NOTE: we don't return the driver that returns a non-zero
446 * value, nor do we leave the reference count incremented for that
447 * driver. If the caller needs to know that info, it must set it
448 * in the callback. It must also be sure to increment the refcount
449 * so it doesn't disappear before returning to the caller.
451 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
452 void *data, int (*fn)(struct device_driver *, void *))
455 struct device_driver *drv;
461 klist_iter_init_node(&bus->p->klist_drivers, &i,
462 start ? &start->p->knode_bus : NULL);
463 while ((drv = next_driver(&i)) && !error)
464 error = fn(drv, data);
468 EXPORT_SYMBOL_GPL(bus_for_each_drv);
471 * bus_add_device - add device to bus
472 * @dev: device being added
474 * - Add device's bus attributes.
475 * - Create links to device's bus.
476 * - Add the device to its bus's list of devices.
478 int bus_add_device(struct device *dev)
480 struct bus_type *bus = bus_get(dev->bus);
484 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
485 error = device_add_groups(dev, bus->dev_groups);
488 error = sysfs_create_link(&bus->p->devices_kset->kobj,
489 &dev->kobj, dev_name(dev));
492 error = sysfs_create_link(&dev->kobj,
493 &dev->bus->p->subsys.kobj, "subsystem");
496 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
501 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
503 device_remove_groups(dev, bus->dev_groups);
510 * bus_probe_device - probe drivers for a new device
511 * @dev: device to probe
513 * - Automatically probe for a driver if the bus allows it.
515 void bus_probe_device(struct device *dev)
517 struct bus_type *bus = dev->bus;
518 struct subsys_interface *sif;
523 if (bus->p->drivers_autoprobe)
524 device_initial_probe(dev);
526 mutex_lock(&bus->p->mutex);
527 list_for_each_entry(sif, &bus->p->interfaces, node)
529 sif->add_dev(dev, sif);
530 mutex_unlock(&bus->p->mutex);
534 * bus_remove_device - remove device from bus
535 * @dev: device to be removed
537 * - Remove device from all interfaces.
538 * - Remove symlink from bus' directory.
539 * - Delete device from bus's list.
540 * - Detach from its driver.
541 * - Drop reference taken in bus_add_device().
543 void bus_remove_device(struct device *dev)
545 struct bus_type *bus = dev->bus;
546 struct subsys_interface *sif;
551 mutex_lock(&bus->p->mutex);
552 list_for_each_entry(sif, &bus->p->interfaces, node)
554 sif->remove_dev(dev, sif);
555 mutex_unlock(&bus->p->mutex);
557 sysfs_remove_link(&dev->kobj, "subsystem");
558 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
560 device_remove_groups(dev, dev->bus->dev_groups);
561 if (klist_node_attached(&dev->p->knode_bus))
562 klist_del(&dev->p->knode_bus);
564 pr_debug("bus: '%s': remove device %s\n",
565 dev->bus->name, dev_name(dev));
566 device_release_driver(dev);
570 static int __must_check add_bind_files(struct device_driver *drv)
574 ret = driver_create_file(drv, &driver_attr_unbind);
576 ret = driver_create_file(drv, &driver_attr_bind);
578 driver_remove_file(drv, &driver_attr_unbind);
583 static void remove_bind_files(struct device_driver *drv)
585 driver_remove_file(drv, &driver_attr_bind);
586 driver_remove_file(drv, &driver_attr_unbind);
589 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
590 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
591 show_drivers_autoprobe, store_drivers_autoprobe);
593 static int add_probe_files(struct bus_type *bus)
597 retval = bus_create_file(bus, &bus_attr_drivers_probe);
601 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
603 bus_remove_file(bus, &bus_attr_drivers_probe);
608 static void remove_probe_files(struct bus_type *bus)
610 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
611 bus_remove_file(bus, &bus_attr_drivers_probe);
614 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
619 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
620 return rc ? rc : count;
622 static DRIVER_ATTR_WO(uevent);
624 static void driver_attach_async(void *_drv, async_cookie_t cookie)
626 struct device_driver *drv = _drv;
629 ret = driver_attach(drv);
631 pr_debug("bus: '%s': driver %s async attach completed: %d\n",
632 drv->bus->name, drv->name, ret);
636 * bus_add_driver - Add a driver to the bus.
639 int bus_add_driver(struct device_driver *drv)
641 struct bus_type *bus;
642 struct driver_private *priv;
645 bus = bus_get(drv->bus);
649 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
651 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
656 klist_init(&priv->klist_devices, NULL, NULL);
659 priv->kobj.kset = bus->p->drivers_kset;
660 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
665 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
666 if (drv->bus->p->drivers_autoprobe) {
667 if (driver_allows_async_probing(drv)) {
668 pr_debug("bus: '%s': probing driver %s asynchronously\n",
669 drv->bus->name, drv->name);
670 async_schedule(driver_attach_async, drv);
672 error = driver_attach(drv);
677 module_add_driver(drv->owner, drv);
679 error = driver_create_file(drv, &driver_attr_uevent);
681 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
682 __func__, drv->name);
684 error = driver_add_groups(drv, bus->drv_groups);
686 /* How the hell do we get out of this pickle? Give up */
687 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
688 __func__, drv->name);
691 if (!drv->suppress_bind_attrs) {
692 error = add_bind_files(drv);
695 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
696 __func__, drv->name);
703 kobject_put(&priv->kobj);
704 /* drv->p is freed in driver_release() */
712 * bus_remove_driver - delete driver from bus's knowledge.
715 * Detach the driver from the devices it controls, and remove
716 * it from its bus's list of drivers. Finally, we drop the reference
717 * to the bus we took in bus_add_driver().
719 void bus_remove_driver(struct device_driver *drv)
724 if (!drv->suppress_bind_attrs)
725 remove_bind_files(drv);
726 driver_remove_groups(drv, drv->bus->drv_groups);
727 driver_remove_file(drv, &driver_attr_uevent);
728 klist_remove(&drv->p->knode_bus);
729 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
731 module_remove_driver(drv);
732 kobject_put(&drv->p->kobj);
736 /* Helper for bus_rescan_devices's iter */
737 static int __must_check bus_rescan_devices_helper(struct device *dev,
743 if (dev->parent && dev->bus->need_parent_lock)
744 device_lock(dev->parent);
745 ret = device_attach(dev);
746 if (dev->parent && dev->bus->need_parent_lock)
747 device_unlock(dev->parent);
749 return ret < 0 ? ret : 0;
753 * bus_rescan_devices - rescan devices on the bus for possible drivers
754 * @bus: the bus to scan.
756 * This function will look for devices on the bus with no driver
757 * attached and rescan it against existing drivers to see if it matches
758 * any by calling device_attach() for the unbound devices.
760 int bus_rescan_devices(struct bus_type *bus)
762 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
764 EXPORT_SYMBOL_GPL(bus_rescan_devices);
767 * device_reprobe - remove driver for a device and probe for a new driver
768 * @dev: the device to reprobe
770 * This function detaches the attached driver (if any) for the given
771 * device and restarts the driver probing process. It is intended
772 * to use if probing criteria changed during a devices lifetime and
773 * driver attachment should change accordingly.
775 int device_reprobe(struct device *dev)
778 if (dev->parent && dev->bus->need_parent_lock)
779 device_lock(dev->parent);
780 device_release_driver(dev);
781 if (dev->parent && dev->bus->need_parent_lock)
782 device_unlock(dev->parent);
784 return bus_rescan_devices_helper(dev, NULL);
786 EXPORT_SYMBOL_GPL(device_reprobe);
789 * find_bus - locate bus by name.
790 * @name: name of bus.
792 * Call kset_find_obj() to iterate over list of buses to
793 * find a bus by name. Return bus if found.
795 * Note that kset_find_obj increments bus' reference count.
798 struct bus_type *find_bus(char *name)
800 struct kobject *k = kset_find_obj(bus_kset, name);
801 return k ? to_bus(k) : NULL;
805 static int bus_add_groups(struct bus_type *bus,
806 const struct attribute_group **groups)
808 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
811 static void bus_remove_groups(struct bus_type *bus,
812 const struct attribute_group **groups)
814 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
817 static void klist_devices_get(struct klist_node *n)
819 struct device_private *dev_prv = to_device_private_bus(n);
820 struct device *dev = dev_prv->device;
825 static void klist_devices_put(struct klist_node *n)
827 struct device_private *dev_prv = to_device_private_bus(n);
828 struct device *dev = dev_prv->device;
833 static ssize_t bus_uevent_store(struct bus_type *bus,
834 const char *buf, size_t count)
838 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
839 return rc ? rc : count;
841 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
844 * bus_register - register a driver-core subsystem
845 * @bus: bus to register
847 * Once we have that, we register the bus with the kobject
848 * infrastructure, then register the children subsystems it has:
849 * the devices and drivers that belong to the subsystem.
851 int bus_register(struct bus_type *bus)
854 struct subsys_private *priv;
855 struct lock_class_key *key = &bus->lock_key;
857 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
864 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
866 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
870 priv->subsys.kobj.kset = bus_kset;
871 priv->subsys.kobj.ktype = &bus_ktype;
872 priv->drivers_autoprobe = 1;
874 retval = kset_register(&priv->subsys);
878 retval = bus_create_file(bus, &bus_attr_uevent);
880 goto bus_uevent_fail;
882 priv->devices_kset = kset_create_and_add("devices", NULL,
884 if (!priv->devices_kset) {
886 goto bus_devices_fail;
889 priv->drivers_kset = kset_create_and_add("drivers", NULL,
891 if (!priv->drivers_kset) {
893 goto bus_drivers_fail;
896 INIT_LIST_HEAD(&priv->interfaces);
897 __mutex_init(&priv->mutex, "subsys mutex", key);
898 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
899 klist_init(&priv->klist_drivers, NULL, NULL);
901 retval = add_probe_files(bus);
903 goto bus_probe_files_fail;
905 retval = bus_add_groups(bus, bus->bus_groups);
907 goto bus_groups_fail;
909 pr_debug("bus: '%s': registered\n", bus->name);
913 remove_probe_files(bus);
914 bus_probe_files_fail:
915 kset_unregister(bus->p->drivers_kset);
917 kset_unregister(bus->p->devices_kset);
919 bus_remove_file(bus, &bus_attr_uevent);
921 kset_unregister(&bus->p->subsys);
927 EXPORT_SYMBOL_GPL(bus_register);
930 * bus_unregister - remove a bus from the system
933 * Unregister the child subsystems and the bus itself.
934 * Finally, we call bus_put() to release the refcount
936 void bus_unregister(struct bus_type *bus)
938 pr_debug("bus: '%s': unregistering\n", bus->name);
940 device_unregister(bus->dev_root);
941 bus_remove_groups(bus, bus->bus_groups);
942 remove_probe_files(bus);
943 kset_unregister(bus->p->drivers_kset);
944 kset_unregister(bus->p->devices_kset);
945 bus_remove_file(bus, &bus_attr_uevent);
946 kset_unregister(&bus->p->subsys);
948 EXPORT_SYMBOL_GPL(bus_unregister);
950 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
952 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
954 EXPORT_SYMBOL_GPL(bus_register_notifier);
956 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
958 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
960 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
962 struct kset *bus_get_kset(struct bus_type *bus)
964 return &bus->p->subsys;
966 EXPORT_SYMBOL_GPL(bus_get_kset);
968 struct klist *bus_get_device_klist(struct bus_type *bus)
970 return &bus->p->klist_devices;
972 EXPORT_SYMBOL_GPL(bus_get_device_klist);
975 * Yes, this forcibly breaks the klist abstraction temporarily. It
976 * just wants to sort the klist, not change reference counts and
977 * take/drop locks rapidly in the process. It does all this while
978 * holding the lock for the list, so objects can't otherwise be
979 * added/removed while we're swizzling.
981 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
982 int (*compare)(const struct device *a,
983 const struct device *b))
985 struct klist_node *n;
986 struct device_private *dev_prv;
989 list_for_each_entry(n, list, n_node) {
990 dev_prv = to_device_private_bus(n);
992 if (compare(a, b) <= 0) {
993 list_move_tail(&a->p->knode_bus.n_node,
994 &b->p->knode_bus.n_node);
998 list_move_tail(&a->p->knode_bus.n_node, list);
1001 void bus_sort_breadthfirst(struct bus_type *bus,
1002 int (*compare)(const struct device *a,
1003 const struct device *b))
1005 LIST_HEAD(sorted_devices);
1006 struct klist_node *n, *tmp;
1007 struct device_private *dev_prv;
1009 struct klist *device_klist;
1011 device_klist = bus_get_device_klist(bus);
1013 spin_lock(&device_klist->k_lock);
1014 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1015 dev_prv = to_device_private_bus(n);
1016 dev = dev_prv->device;
1017 device_insertion_sort_klist(dev, &sorted_devices, compare);
1019 list_splice(&sorted_devices, &device_klist->k_list);
1020 spin_unlock(&device_klist->k_lock);
1022 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1025 * subsys_dev_iter_init - initialize subsys device iterator
1026 * @iter: subsys iterator to initialize
1027 * @subsys: the subsys we wanna iterate over
1028 * @start: the device to start iterating from, if any
1029 * @type: device_type of the devices to iterate over, NULL for all
1031 * Initialize subsys iterator @iter such that it iterates over devices
1032 * of @subsys. If @start is set, the list iteration will start there,
1033 * otherwise if it is NULL, the iteration starts at the beginning of
1036 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1037 struct device *start, const struct device_type *type)
1039 struct klist_node *start_knode = NULL;
1042 start_knode = &start->p->knode_bus;
1043 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1046 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1049 * subsys_dev_iter_next - iterate to the next device
1050 * @iter: subsys iterator to proceed
1052 * Proceed @iter to the next device and return it. Returns NULL if
1053 * iteration is complete.
1055 * The returned device is referenced and won't be released till
1056 * iterator is proceed to the next device or exited. The caller is
1057 * free to do whatever it wants to do with the device including
1058 * calling back into subsys code.
1060 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1062 struct klist_node *knode;
1066 knode = klist_next(&iter->ki);
1069 dev = to_device_private_bus(knode)->device;
1070 if (!iter->type || iter->type == dev->type)
1074 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1077 * subsys_dev_iter_exit - finish iteration
1078 * @iter: subsys iterator to finish
1080 * Finish an iteration. Always call this function after iteration is
1081 * complete whether the iteration ran till the end or not.
1083 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1085 klist_iter_exit(&iter->ki);
1087 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1089 int subsys_interface_register(struct subsys_interface *sif)
1091 struct bus_type *subsys;
1092 struct subsys_dev_iter iter;
1095 if (!sif || !sif->subsys)
1098 subsys = bus_get(sif->subsys);
1102 mutex_lock(&subsys->p->mutex);
1103 list_add_tail(&sif->node, &subsys->p->interfaces);
1105 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1106 while ((dev = subsys_dev_iter_next(&iter)))
1107 sif->add_dev(dev, sif);
1108 subsys_dev_iter_exit(&iter);
1110 mutex_unlock(&subsys->p->mutex);
1114 EXPORT_SYMBOL_GPL(subsys_interface_register);
1116 void subsys_interface_unregister(struct subsys_interface *sif)
1118 struct bus_type *subsys;
1119 struct subsys_dev_iter iter;
1122 if (!sif || !sif->subsys)
1125 subsys = sif->subsys;
1127 mutex_lock(&subsys->p->mutex);
1128 list_del_init(&sif->node);
1129 if (sif->remove_dev) {
1130 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1131 while ((dev = subsys_dev_iter_next(&iter)))
1132 sif->remove_dev(dev, sif);
1133 subsys_dev_iter_exit(&iter);
1135 mutex_unlock(&subsys->p->mutex);
1139 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1141 static void system_root_device_release(struct device *dev)
1146 static int subsys_register(struct bus_type *subsys,
1147 const struct attribute_group **groups,
1148 struct kobject *parent_of_root)
1153 err = bus_register(subsys);
1157 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1163 err = dev_set_name(dev, "%s", subsys->name);
1167 dev->kobj.parent = parent_of_root;
1168 dev->groups = groups;
1169 dev->release = system_root_device_release;
1171 err = device_register(dev);
1175 subsys->dev_root = dev;
1184 bus_unregister(subsys);
1189 * subsys_system_register - register a subsystem at /sys/devices/system/
1190 * @subsys: system subsystem
1191 * @groups: default attributes for the root device
1193 * All 'system' subsystems have a /sys/devices/system/<name> root device
1194 * with the name of the subsystem. The root device can carry subsystem-
1195 * wide attributes. All registered devices are below this single root
1196 * device and are named after the subsystem with a simple enumeration
1197 * number appended. The registered devices are not explicitly named;
1198 * only 'id' in the device needs to be set.
1200 * Do not use this interface for anything new, it exists for compatibility
1201 * with bad ideas only. New subsystems should use plain subsystems; and
1202 * add the subsystem-wide attributes should be added to the subsystem
1203 * directory itself and not some create fake root-device placed in
1204 * /sys/devices/system/<name>.
1206 int subsys_system_register(struct bus_type *subsys,
1207 const struct attribute_group **groups)
1209 return subsys_register(subsys, groups, &system_kset->kobj);
1211 EXPORT_SYMBOL_GPL(subsys_system_register);
1214 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1215 * @subsys: virtual subsystem
1216 * @groups: default attributes for the root device
1218 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1219 * with the name of the subystem. The root device can carry subsystem-wide
1220 * attributes. All registered devices are below this single root device.
1221 * There's no restriction on device naming. This is for kernel software
1222 * constructs which need sysfs interface.
1224 int subsys_virtual_register(struct bus_type *subsys,
1225 const struct attribute_group **groups)
1227 struct kobject *virtual_dir;
1229 virtual_dir = virtual_device_parent(NULL);
1233 return subsys_register(subsys, groups, virtual_dir);
1235 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1237 int __init buses_init(void)
1239 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1243 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);