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);
472 static int device_add_attrs(struct bus_type *bus, struct device *dev)
480 for (i = 0; bus->dev_attrs[i].attr.name; i++) {
481 error = device_create_file(dev, &bus->dev_attrs[i]);
484 device_remove_file(dev, &bus->dev_attrs[i]);
491 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
495 if (bus->dev_attrs) {
496 for (i = 0; bus->dev_attrs[i].attr.name; i++)
497 device_remove_file(dev, &bus->dev_attrs[i]);
502 * bus_add_device - add device to bus
503 * @dev: device being added
505 * - Add device's bus attributes.
506 * - Create links to device's bus.
507 * - Add the device to its bus's list of devices.
509 int bus_add_device(struct device *dev)
511 struct bus_type *bus = bus_get(dev->bus);
515 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
516 error = device_add_attrs(bus, dev);
519 error = device_add_groups(dev, bus->dev_groups);
522 error = sysfs_create_link(&bus->p->devices_kset->kobj,
523 &dev->kobj, dev_name(dev));
526 error = sysfs_create_link(&dev->kobj,
527 &dev->bus->p->subsys.kobj, "subsystem");
530 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
535 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
537 device_remove_groups(dev, bus->dev_groups);
539 device_remove_attrs(bus, dev);
546 * bus_probe_device - probe drivers for a new device
547 * @dev: device to probe
549 * - Automatically probe for a driver if the bus allows it.
551 void bus_probe_device(struct device *dev)
553 struct bus_type *bus = dev->bus;
554 struct subsys_interface *sif;
559 if (bus->p->drivers_autoprobe)
560 device_initial_probe(dev);
562 mutex_lock(&bus->p->mutex);
563 list_for_each_entry(sif, &bus->p->interfaces, node)
565 sif->add_dev(dev, sif);
566 mutex_unlock(&bus->p->mutex);
570 * bus_remove_device - remove device from bus
571 * @dev: device to be removed
573 * - Remove device from all interfaces.
574 * - Remove symlink from bus' directory.
575 * - Delete device from bus's list.
576 * - Detach from its driver.
577 * - Drop reference taken in bus_add_device().
579 void bus_remove_device(struct device *dev)
581 struct bus_type *bus = dev->bus;
582 struct subsys_interface *sif;
587 mutex_lock(&bus->p->mutex);
588 list_for_each_entry(sif, &bus->p->interfaces, node)
590 sif->remove_dev(dev, sif);
591 mutex_unlock(&bus->p->mutex);
593 sysfs_remove_link(&dev->kobj, "subsystem");
594 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
596 device_remove_attrs(dev->bus, dev);
597 device_remove_groups(dev, dev->bus->dev_groups);
598 if (klist_node_attached(&dev->p->knode_bus))
599 klist_del(&dev->p->knode_bus);
601 pr_debug("bus: '%s': remove device %s\n",
602 dev->bus->name, dev_name(dev));
603 device_release_driver(dev);
607 static int __must_check add_bind_files(struct device_driver *drv)
611 ret = driver_create_file(drv, &driver_attr_unbind);
613 ret = driver_create_file(drv, &driver_attr_bind);
615 driver_remove_file(drv, &driver_attr_unbind);
620 static void remove_bind_files(struct device_driver *drv)
622 driver_remove_file(drv, &driver_attr_bind);
623 driver_remove_file(drv, &driver_attr_unbind);
626 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
627 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
628 show_drivers_autoprobe, store_drivers_autoprobe);
630 static int add_probe_files(struct bus_type *bus)
634 retval = bus_create_file(bus, &bus_attr_drivers_probe);
638 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
640 bus_remove_file(bus, &bus_attr_drivers_probe);
645 static void remove_probe_files(struct bus_type *bus)
647 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
648 bus_remove_file(bus, &bus_attr_drivers_probe);
651 static ssize_t uevent_store(struct device_driver *drv, const char *buf,
654 enum kobject_action action;
656 if (kobject_action_type(buf, count, &action) == 0)
657 kobject_uevent(&drv->p->kobj, action);
660 static DRIVER_ATTR_WO(uevent);
662 static void driver_attach_async(void *_drv, async_cookie_t cookie)
664 struct device_driver *drv = _drv;
667 ret = driver_attach(drv);
669 pr_debug("bus: '%s': driver %s async attach completed: %d\n",
670 drv->bus->name, drv->name, ret);
674 * bus_add_driver - Add a driver to the bus.
677 int bus_add_driver(struct device_driver *drv)
679 struct bus_type *bus;
680 struct driver_private *priv;
683 bus = bus_get(drv->bus);
687 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
689 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
694 klist_init(&priv->klist_devices, NULL, NULL);
697 priv->kobj.kset = bus->p->drivers_kset;
698 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
703 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
704 if (drv->bus->p->drivers_autoprobe) {
705 if (driver_allows_async_probing(drv)) {
706 pr_debug("bus: '%s': probing driver %s asynchronously\n",
707 drv->bus->name, drv->name);
708 async_schedule(driver_attach_async, drv);
710 error = driver_attach(drv);
715 module_add_driver(drv->owner, drv);
717 error = driver_create_file(drv, &driver_attr_uevent);
719 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
720 __func__, drv->name);
722 error = driver_add_groups(drv, bus->drv_groups);
724 /* How the hell do we get out of this pickle? Give up */
725 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
726 __func__, drv->name);
729 if (!drv->suppress_bind_attrs) {
730 error = add_bind_files(drv);
733 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
734 __func__, drv->name);
741 kobject_put(&priv->kobj);
742 /* drv->p is freed in driver_release() */
750 * bus_remove_driver - delete driver from bus's knowledge.
753 * Detach the driver from the devices it controls, and remove
754 * it from its bus's list of drivers. Finally, we drop the reference
755 * to the bus we took in bus_add_driver().
757 void bus_remove_driver(struct device_driver *drv)
762 if (!drv->suppress_bind_attrs)
763 remove_bind_files(drv);
764 driver_remove_groups(drv, drv->bus->drv_groups);
765 driver_remove_file(drv, &driver_attr_uevent);
766 klist_remove(&drv->p->knode_bus);
767 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
769 module_remove_driver(drv);
770 kobject_put(&drv->p->kobj);
774 /* Helper for bus_rescan_devices's iter */
775 static int __must_check bus_rescan_devices_helper(struct device *dev,
781 if (dev->parent) /* Needed for USB */
782 device_lock(dev->parent);
783 ret = device_attach(dev);
785 device_unlock(dev->parent);
787 return ret < 0 ? ret : 0;
791 * bus_rescan_devices - rescan devices on the bus for possible drivers
792 * @bus: the bus to scan.
794 * This function will look for devices on the bus with no driver
795 * attached and rescan it against existing drivers to see if it matches
796 * any by calling device_attach() for the unbound devices.
798 int bus_rescan_devices(struct bus_type *bus)
800 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
802 EXPORT_SYMBOL_GPL(bus_rescan_devices);
805 * device_reprobe - remove driver for a device and probe for a new driver
806 * @dev: the device to reprobe
808 * This function detaches the attached driver (if any) for the given
809 * device and restarts the driver probing process. It is intended
810 * to use if probing criteria changed during a devices lifetime and
811 * driver attachment should change accordingly.
813 int device_reprobe(struct device *dev)
816 if (dev->parent) /* Needed for USB */
817 device_lock(dev->parent);
818 device_release_driver(dev);
820 device_unlock(dev->parent);
822 return bus_rescan_devices_helper(dev, NULL);
824 EXPORT_SYMBOL_GPL(device_reprobe);
827 * find_bus - locate bus by name.
828 * @name: name of bus.
830 * Call kset_find_obj() to iterate over list of buses to
831 * find a bus by name. Return bus if found.
833 * Note that kset_find_obj increments bus' reference count.
836 struct bus_type *find_bus(char *name)
838 struct kobject *k = kset_find_obj(bus_kset, name);
839 return k ? to_bus(k) : NULL;
843 static int bus_add_groups(struct bus_type *bus,
844 const struct attribute_group **groups)
846 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
849 static void bus_remove_groups(struct bus_type *bus,
850 const struct attribute_group **groups)
852 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
855 static void klist_devices_get(struct klist_node *n)
857 struct device_private *dev_prv = to_device_private_bus(n);
858 struct device *dev = dev_prv->device;
863 static void klist_devices_put(struct klist_node *n)
865 struct device_private *dev_prv = to_device_private_bus(n);
866 struct device *dev = dev_prv->device;
871 static ssize_t bus_uevent_store(struct bus_type *bus,
872 const char *buf, size_t count)
874 enum kobject_action action;
876 if (kobject_action_type(buf, count, &action) == 0)
877 kobject_uevent(&bus->p->subsys.kobj, action);
880 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
883 * bus_register - register a driver-core subsystem
884 * @bus: bus to register
886 * Once we have that, we register the bus with the kobject
887 * infrastructure, then register the children subsystems it has:
888 * the devices and drivers that belong to the subsystem.
890 int bus_register(struct bus_type *bus)
893 struct subsys_private *priv;
894 struct lock_class_key *key = &bus->lock_key;
896 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
903 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
905 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
909 priv->subsys.kobj.kset = bus_kset;
910 priv->subsys.kobj.ktype = &bus_ktype;
911 priv->drivers_autoprobe = 1;
913 retval = kset_register(&priv->subsys);
917 retval = bus_create_file(bus, &bus_attr_uevent);
919 goto bus_uevent_fail;
921 priv->devices_kset = kset_create_and_add("devices", NULL,
923 if (!priv->devices_kset) {
925 goto bus_devices_fail;
928 priv->drivers_kset = kset_create_and_add("drivers", NULL,
930 if (!priv->drivers_kset) {
932 goto bus_drivers_fail;
935 INIT_LIST_HEAD(&priv->interfaces);
936 __mutex_init(&priv->mutex, "subsys mutex", key);
937 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
938 klist_init(&priv->klist_drivers, NULL, NULL);
940 retval = add_probe_files(bus);
942 goto bus_probe_files_fail;
944 retval = bus_add_groups(bus, bus->bus_groups);
946 goto bus_groups_fail;
948 pr_debug("bus: '%s': registered\n", bus->name);
952 remove_probe_files(bus);
953 bus_probe_files_fail:
954 kset_unregister(bus->p->drivers_kset);
956 kset_unregister(bus->p->devices_kset);
958 bus_remove_file(bus, &bus_attr_uevent);
960 kset_unregister(&bus->p->subsys);
966 EXPORT_SYMBOL_GPL(bus_register);
969 * bus_unregister - remove a bus from the system
972 * Unregister the child subsystems and the bus itself.
973 * Finally, we call bus_put() to release the refcount
975 void bus_unregister(struct bus_type *bus)
977 pr_debug("bus: '%s': unregistering\n", bus->name);
979 device_unregister(bus->dev_root);
980 bus_remove_groups(bus, bus->bus_groups);
981 remove_probe_files(bus);
982 kset_unregister(bus->p->drivers_kset);
983 kset_unregister(bus->p->devices_kset);
984 bus_remove_file(bus, &bus_attr_uevent);
985 kset_unregister(&bus->p->subsys);
987 EXPORT_SYMBOL_GPL(bus_unregister);
989 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
991 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
993 EXPORT_SYMBOL_GPL(bus_register_notifier);
995 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
997 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
999 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
1001 struct kset *bus_get_kset(struct bus_type *bus)
1003 return &bus->p->subsys;
1005 EXPORT_SYMBOL_GPL(bus_get_kset);
1007 struct klist *bus_get_device_klist(struct bus_type *bus)
1009 return &bus->p->klist_devices;
1011 EXPORT_SYMBOL_GPL(bus_get_device_klist);
1014 * Yes, this forcibly breaks the klist abstraction temporarily. It
1015 * just wants to sort the klist, not change reference counts and
1016 * take/drop locks rapidly in the process. It does all this while
1017 * holding the lock for the list, so objects can't otherwise be
1018 * added/removed while we're swizzling.
1020 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1021 int (*compare)(const struct device *a,
1022 const struct device *b))
1024 struct klist_node *n;
1025 struct device_private *dev_prv;
1028 list_for_each_entry(n, list, n_node) {
1029 dev_prv = to_device_private_bus(n);
1030 b = dev_prv->device;
1031 if (compare(a, b) <= 0) {
1032 list_move_tail(&a->p->knode_bus.n_node,
1033 &b->p->knode_bus.n_node);
1037 list_move_tail(&a->p->knode_bus.n_node, list);
1040 void bus_sort_breadthfirst(struct bus_type *bus,
1041 int (*compare)(const struct device *a,
1042 const struct device *b))
1044 LIST_HEAD(sorted_devices);
1045 struct klist_node *n, *tmp;
1046 struct device_private *dev_prv;
1048 struct klist *device_klist;
1050 device_klist = bus_get_device_klist(bus);
1052 spin_lock(&device_klist->k_lock);
1053 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1054 dev_prv = to_device_private_bus(n);
1055 dev = dev_prv->device;
1056 device_insertion_sort_klist(dev, &sorted_devices, compare);
1058 list_splice(&sorted_devices, &device_klist->k_list);
1059 spin_unlock(&device_klist->k_lock);
1061 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1064 * subsys_dev_iter_init - initialize subsys device iterator
1065 * @iter: subsys iterator to initialize
1066 * @subsys: the subsys we wanna iterate over
1067 * @start: the device to start iterating from, if any
1068 * @type: device_type of the devices to iterate over, NULL for all
1070 * Initialize subsys iterator @iter such that it iterates over devices
1071 * of @subsys. If @start is set, the list iteration will start there,
1072 * otherwise if it is NULL, the iteration starts at the beginning of
1075 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1076 struct device *start, const struct device_type *type)
1078 struct klist_node *start_knode = NULL;
1081 start_knode = &start->p->knode_bus;
1082 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1085 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1088 * subsys_dev_iter_next - iterate to the next device
1089 * @iter: subsys iterator to proceed
1091 * Proceed @iter to the next device and return it. Returns NULL if
1092 * iteration is complete.
1094 * The returned device is referenced and won't be released till
1095 * iterator is proceed to the next device or exited. The caller is
1096 * free to do whatever it wants to do with the device including
1097 * calling back into subsys code.
1099 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1101 struct klist_node *knode;
1105 knode = klist_next(&iter->ki);
1108 dev = to_device_private_bus(knode)->device;
1109 if (!iter->type || iter->type == dev->type)
1113 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1116 * subsys_dev_iter_exit - finish iteration
1117 * @iter: subsys iterator to finish
1119 * Finish an iteration. Always call this function after iteration is
1120 * complete whether the iteration ran till the end or not.
1122 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1124 klist_iter_exit(&iter->ki);
1126 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1128 int subsys_interface_register(struct subsys_interface *sif)
1130 struct bus_type *subsys;
1131 struct subsys_dev_iter iter;
1134 if (!sif || !sif->subsys)
1137 subsys = bus_get(sif->subsys);
1141 mutex_lock(&subsys->p->mutex);
1142 list_add_tail(&sif->node, &subsys->p->interfaces);
1144 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1145 while ((dev = subsys_dev_iter_next(&iter)))
1146 sif->add_dev(dev, sif);
1147 subsys_dev_iter_exit(&iter);
1149 mutex_unlock(&subsys->p->mutex);
1153 EXPORT_SYMBOL_GPL(subsys_interface_register);
1155 void subsys_interface_unregister(struct subsys_interface *sif)
1157 struct bus_type *subsys;
1158 struct subsys_dev_iter iter;
1161 if (!sif || !sif->subsys)
1164 subsys = sif->subsys;
1166 mutex_lock(&subsys->p->mutex);
1167 list_del_init(&sif->node);
1168 if (sif->remove_dev) {
1169 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1170 while ((dev = subsys_dev_iter_next(&iter)))
1171 sif->remove_dev(dev, sif);
1172 subsys_dev_iter_exit(&iter);
1174 mutex_unlock(&subsys->p->mutex);
1178 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1180 static void system_root_device_release(struct device *dev)
1185 static int subsys_register(struct bus_type *subsys,
1186 const struct attribute_group **groups,
1187 struct kobject *parent_of_root)
1192 err = bus_register(subsys);
1196 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1202 err = dev_set_name(dev, "%s", subsys->name);
1206 dev->kobj.parent = parent_of_root;
1207 dev->groups = groups;
1208 dev->release = system_root_device_release;
1210 err = device_register(dev);
1214 subsys->dev_root = dev;
1223 bus_unregister(subsys);
1228 * subsys_system_register - register a subsystem at /sys/devices/system/
1229 * @subsys: system subsystem
1230 * @groups: default attributes for the root device
1232 * All 'system' subsystems have a /sys/devices/system/<name> root device
1233 * with the name of the subsystem. The root device can carry subsystem-
1234 * wide attributes. All registered devices are below this single root
1235 * device and are named after the subsystem with a simple enumeration
1236 * number appended. The registered devices are not explicitly named;
1237 * only 'id' in the device needs to be set.
1239 * Do not use this interface for anything new, it exists for compatibility
1240 * with bad ideas only. New subsystems should use plain subsystems; and
1241 * add the subsystem-wide attributes should be added to the subsystem
1242 * directory itself and not some create fake root-device placed in
1243 * /sys/devices/system/<name>.
1245 int subsys_system_register(struct bus_type *subsys,
1246 const struct attribute_group **groups)
1248 return subsys_register(subsys, groups, &system_kset->kobj);
1250 EXPORT_SYMBOL_GPL(subsys_system_register);
1253 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1254 * @subsys: virtual subsystem
1255 * @groups: default attributes for the root device
1257 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1258 * with the name of the subystem. The root device can carry subsystem-wide
1259 * attributes. All registered devices are below this single root device.
1260 * There's no restriction on device naming. This is for kernel software
1261 * constructs which need sysfs interface.
1263 int subsys_virtual_register(struct bus_type *subsys,
1264 const struct attribute_group **groups)
1266 struct kobject *virtual_dir;
1268 virtual_dir = virtual_device_parent(NULL);
1272 return subsys_register(subsys, groups, virtual_dir);
1274 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1276 int __init buses_init(void)
1278 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1282 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);