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/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>
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)
35 static int __must_check bus_rescan_devices_helper(struct device *dev,
38 static struct bus_type *bus_get(struct bus_type *bus)
41 kset_get(&bus->p->subsys);
47 static void bus_put(struct bus_type *bus)
50 kset_put(&bus->p->subsys);
53 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
56 struct driver_attribute *drv_attr = to_drv_attr(attr);
57 struct driver_private *drv_priv = to_driver(kobj);
61 ret = drv_attr->show(drv_priv->driver, buf);
65 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
66 const char *buf, size_t count)
68 struct driver_attribute *drv_attr = to_drv_attr(attr);
69 struct driver_private *drv_priv = to_driver(kobj);
73 ret = drv_attr->store(drv_priv->driver, buf, count);
77 static const struct sysfs_ops driver_sysfs_ops = {
78 .show = drv_attr_show,
79 .store = drv_attr_store,
82 static void driver_release(struct kobject *kobj)
84 struct driver_private *drv_priv = to_driver(kobj);
86 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
90 static struct kobj_type driver_ktype = {
91 .sysfs_ops = &driver_sysfs_ops,
92 .release = driver_release,
96 * sysfs bindings for buses
98 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
101 struct bus_attribute *bus_attr = to_bus_attr(attr);
102 struct subsys_private *subsys_priv = to_subsys_private(kobj);
106 ret = bus_attr->show(subsys_priv->bus, buf);
110 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
111 const char *buf, size_t count)
113 struct bus_attribute *bus_attr = to_bus_attr(attr);
114 struct subsys_private *subsys_priv = to_subsys_private(kobj);
118 ret = bus_attr->store(subsys_priv->bus, buf, count);
122 static const struct sysfs_ops bus_sysfs_ops = {
123 .show = bus_attr_show,
124 .store = bus_attr_store,
127 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
131 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
137 EXPORT_SYMBOL_GPL(bus_create_file);
139 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
142 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
146 EXPORT_SYMBOL_GPL(bus_remove_file);
148 static struct kobj_type bus_ktype = {
149 .sysfs_ops = &bus_sysfs_ops,
152 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
154 struct kobj_type *ktype = get_ktype(kobj);
156 if (ktype == &bus_ktype)
161 static const struct kset_uevent_ops bus_uevent_ops = {
162 .filter = bus_uevent_filter,
165 static struct kset *bus_kset;
168 #ifdef CONFIG_HOTPLUG
169 /* Manually detach a device from its associated driver. */
170 static ssize_t driver_unbind(struct device_driver *drv,
171 const char *buf, size_t count)
173 struct bus_type *bus = bus_get(drv->bus);
177 dev = bus_find_device_by_name(bus, NULL, buf);
178 if (dev && dev->driver == drv) {
179 if (dev->parent) /* Needed for USB */
180 device_lock(dev->parent);
181 device_release_driver(dev);
183 device_unlock(dev->parent);
190 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
193 * Manually attach a device to a driver.
194 * Note: the driver must want to bind to the device,
195 * it is not possible to override the driver's id table.
197 static ssize_t driver_bind(struct device_driver *drv,
198 const char *buf, size_t count)
200 struct bus_type *bus = bus_get(drv->bus);
204 dev = bus_find_device_by_name(bus, NULL, buf);
205 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
206 if (dev->parent) /* Needed for USB */
207 device_lock(dev->parent);
209 err = driver_probe_device(drv, dev);
212 device_unlock(dev->parent);
217 } else if (err == 0) {
218 /* driver didn't accept device */
226 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
228 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
230 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
233 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
234 const char *buf, size_t count)
237 bus->p->drivers_autoprobe = 0;
239 bus->p->drivers_autoprobe = 1;
243 static ssize_t store_drivers_probe(struct bus_type *bus,
244 const char *buf, size_t count)
248 dev = bus_find_device_by_name(bus, NULL, buf);
251 if (bus_rescan_devices_helper(dev, NULL) != 0)
257 static struct device *next_device(struct klist_iter *i)
259 struct klist_node *n = klist_next(i);
260 struct device *dev = NULL;
261 struct device_private *dev_prv;
264 dev_prv = to_device_private_bus(n);
265 dev = dev_prv->device;
271 * bus_for_each_dev - device iterator.
273 * @start: device to start iterating from.
274 * @data: data for the callback.
275 * @fn: function to be called for each device.
277 * Iterate over @bus's list of devices, and call @fn for each,
278 * passing it @data. If @start is not NULL, we use that device to
279 * begin iterating from.
281 * We check the return of @fn each time. If it returns anything
282 * other than 0, we break out and return that value.
284 * NOTE: The device that returns a non-zero value is not retained
285 * in any way, nor is its refcount incremented. If the caller needs
286 * to retain this data, it should do so, and increment the reference
287 * count in the supplied callback.
289 int bus_for_each_dev(struct bus_type *bus, struct device *start,
290 void *data, int (*fn)(struct device *, void *))
299 error = klist_iter_init_node(&bus->p->klist_devices, &i,
300 (start ? &start->p->knode_bus : NULL));
302 while ((dev = next_device(&i)) && !error)
303 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, void *data,
327 int (*match)(struct device *dev, void *data))
335 if (klist_iter_init_node(&bus->p->klist_devices, &i,
336 (start ? &start->p->knode_bus : NULL)) < 0)
339 while ((dev = next_device(&i)))
340 if (match(dev, data) && get_device(dev))
345 EXPORT_SYMBOL_GPL(bus_find_device);
347 static int match_name(struct device *dev, void *data)
349 const char *name = data;
351 return sysfs_streq(name, dev_name(dev));
355 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
357 * @start: Device to begin with
358 * @name: name of the device to match
360 * This is similar to the bus_find_device() function above, but it handles
361 * searching by a name automatically, no need to write another strcmp matching
364 struct device *bus_find_device_by_name(struct bus_type *bus,
365 struct device *start, const char *name)
367 return bus_find_device(bus, start, (void *)name, match_name);
369 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
372 * subsys_find_device_by_id - find a device with a specific enumeration number
374 * @id: index 'id' in struct device
375 * @hint: device to check first
377 * Check the hint's next object and if it is a match return it directly,
378 * otherwise, fall back to a full list search. Either way a reference for
379 * the returned object is taken.
381 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
391 if (klist_iter_init_node(&subsys->p->klist_devices, &i,
392 &hint->p->knode_bus) < 0)
394 dev = next_device(&i);
395 if (dev && dev->id == id && get_device(dev)) {
402 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
403 while ((dev = next_device(&i))) {
404 if (dev->id == id && get_device(dev)) {
412 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
414 static struct device_driver *next_driver(struct klist_iter *i)
416 struct klist_node *n = klist_next(i);
417 struct driver_private *drv_priv;
420 drv_priv = container_of(n, struct driver_private, knode_bus);
421 return drv_priv->driver;
427 * bus_for_each_drv - driver iterator
428 * @bus: bus we're dealing with.
429 * @start: driver to start iterating on.
430 * @data: data to pass to the callback.
431 * @fn: function to call for each driver.
433 * This is nearly identical to the device iterator above.
434 * We iterate over each driver that belongs to @bus, and call
435 * @fn for each. If @fn returns anything but 0, we break out
436 * and return it. If @start is not NULL, we use it as the head
439 * NOTE: we don't return the driver that returns a non-zero
440 * value, nor do we leave the reference count incremented for that
441 * driver. If the caller needs to know that info, it must set it
442 * in the callback. It must also be sure to increment the refcount
443 * so it doesn't disappear before returning to the caller.
445 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
446 void *data, int (*fn)(struct device_driver *, void *))
449 struct device_driver *drv;
455 error = klist_iter_init_node(&bus->p->klist_drivers, &i,
456 start ? &start->p->knode_bus : NULL);
458 while ((drv = next_driver(&i)) && !error)
459 error = fn(drv, data);
464 EXPORT_SYMBOL_GPL(bus_for_each_drv);
466 static int device_add_attrs(struct bus_type *bus, struct device *dev)
474 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
475 error = device_create_file(dev, &bus->dev_attrs[i]);
478 device_remove_file(dev, &bus->dev_attrs[i]);
485 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
489 if (bus->dev_attrs) {
490 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
491 device_remove_file(dev, &bus->dev_attrs[i]);
496 * bus_add_device - add device to bus
497 * @dev: device being added
499 * - Add device's bus attributes.
500 * - Create links to device's bus.
501 * - Add the device to its bus's list of devices.
503 int bus_add_device(struct device *dev)
505 struct bus_type *bus = bus_get(dev->bus);
509 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
510 error = device_add_attrs(bus, dev);
513 error = sysfs_create_link(&bus->p->devices_kset->kobj,
514 &dev->kobj, dev_name(dev));
517 error = sysfs_create_link(&dev->kobj,
518 &dev->bus->p->subsys.kobj, "subsystem");
521 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
526 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
528 device_remove_attrs(bus, dev);
535 * bus_probe_device - probe drivers for a new device
536 * @dev: device to probe
538 * - Automatically probe for a driver if the bus allows it.
540 void bus_probe_device(struct device *dev)
542 struct bus_type *bus = dev->bus;
543 struct subsys_interface *sif;
549 if (bus->p->drivers_autoprobe) {
550 ret = device_attach(dev);
554 mutex_lock(&bus->p->mutex);
555 list_for_each_entry(sif, &bus->p->interfaces, node)
557 sif->add_dev(dev, sif);
558 mutex_unlock(&bus->p->mutex);
562 * bus_remove_device - remove device from bus
563 * @dev: device to be removed
565 * - Remove device from all interfaces.
566 * - Remove symlink from bus' directory.
567 * - Delete device from bus's list.
568 * - Detach from its driver.
569 * - Drop reference taken in bus_add_device().
571 void bus_remove_device(struct device *dev)
573 struct bus_type *bus = dev->bus;
574 struct subsys_interface *sif;
579 mutex_lock(&bus->p->mutex);
580 list_for_each_entry(sif, &bus->p->interfaces, node)
582 sif->remove_dev(dev, sif);
583 mutex_unlock(&bus->p->mutex);
585 sysfs_remove_link(&dev->kobj, "subsystem");
586 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
588 device_remove_attrs(dev->bus, dev);
589 if (klist_node_attached(&dev->p->knode_bus))
590 klist_del(&dev->p->knode_bus);
592 pr_debug("bus: '%s': remove device %s\n",
593 dev->bus->name, dev_name(dev));
594 device_release_driver(dev);
598 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
603 if (bus->drv_attrs) {
604 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
605 error = driver_create_file(drv, &bus->drv_attrs[i]);
614 driver_remove_file(drv, &bus->drv_attrs[i]);
618 static void driver_remove_attrs(struct bus_type *bus,
619 struct device_driver *drv)
623 if (bus->drv_attrs) {
624 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
625 driver_remove_file(drv, &bus->drv_attrs[i]);
629 #ifdef CONFIG_HOTPLUG
631 * Thanks to drivers making their tables __devinit, we can't allow manual
632 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
634 static int __must_check add_bind_files(struct device_driver *drv)
638 ret = driver_create_file(drv, &driver_attr_unbind);
640 ret = driver_create_file(drv, &driver_attr_bind);
642 driver_remove_file(drv, &driver_attr_unbind);
647 static void remove_bind_files(struct device_driver *drv)
649 driver_remove_file(drv, &driver_attr_bind);
650 driver_remove_file(drv, &driver_attr_unbind);
653 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
654 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
655 show_drivers_autoprobe, store_drivers_autoprobe);
657 static int add_probe_files(struct bus_type *bus)
661 retval = bus_create_file(bus, &bus_attr_drivers_probe);
665 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
667 bus_remove_file(bus, &bus_attr_drivers_probe);
672 static void remove_probe_files(struct bus_type *bus)
674 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
675 bus_remove_file(bus, &bus_attr_drivers_probe);
678 static inline int add_bind_files(struct device_driver *drv) { return 0; }
679 static inline void remove_bind_files(struct device_driver *drv) {}
680 static inline int add_probe_files(struct bus_type *bus) { return 0; }
681 static inline void remove_probe_files(struct bus_type *bus) {}
684 static ssize_t driver_uevent_store(struct device_driver *drv,
685 const char *buf, size_t count)
687 enum kobject_action action;
689 if (kobject_action_type(buf, count, &action) == 0)
690 kobject_uevent(&drv->p->kobj, action);
693 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
696 * bus_add_driver - Add a driver to the bus.
699 int bus_add_driver(struct device_driver *drv)
701 struct bus_type *bus;
702 struct driver_private *priv;
705 bus = bus_get(drv->bus);
709 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
711 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
716 klist_init(&priv->klist_devices, NULL, NULL);
719 priv->kobj.kset = bus->p->drivers_kset;
720 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
725 if (drv->bus->p->drivers_autoprobe) {
726 error = driver_attach(drv);
730 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
731 module_add_driver(drv->owner, drv);
733 error = driver_create_file(drv, &driver_attr_uevent);
735 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
736 __func__, drv->name);
738 error = driver_add_attrs(bus, drv);
740 /* How the hell do we get out of this pickle? Give up */
741 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
742 __func__, drv->name);
745 if (!drv->suppress_bind_attrs) {
746 error = add_bind_files(drv);
749 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
750 __func__, drv->name);
754 kobject_uevent(&priv->kobj, KOBJ_ADD);
758 kobject_put(&priv->kobj);
767 * bus_remove_driver - delete driver from bus's knowledge.
770 * Detach the driver from the devices it controls, and remove
771 * it from its bus's list of drivers. Finally, we drop the reference
772 * to the bus we took in bus_add_driver().
774 void bus_remove_driver(struct device_driver *drv)
779 if (!drv->suppress_bind_attrs)
780 remove_bind_files(drv);
781 driver_remove_attrs(drv->bus, drv);
782 driver_remove_file(drv, &driver_attr_uevent);
783 klist_remove(&drv->p->knode_bus);
784 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
786 module_remove_driver(drv);
787 kobject_put(&drv->p->kobj);
791 /* Helper for bus_rescan_devices's iter */
792 static int __must_check bus_rescan_devices_helper(struct device *dev,
798 if (dev->parent) /* Needed for USB */
799 device_lock(dev->parent);
800 ret = device_attach(dev);
802 device_unlock(dev->parent);
804 return ret < 0 ? ret : 0;
808 * bus_rescan_devices - rescan devices on the bus for possible drivers
809 * @bus: the bus to scan.
811 * This function will look for devices on the bus with no driver
812 * attached and rescan it against existing drivers to see if it matches
813 * any by calling device_attach() for the unbound devices.
815 int bus_rescan_devices(struct bus_type *bus)
817 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
819 EXPORT_SYMBOL_GPL(bus_rescan_devices);
822 * device_reprobe - remove driver for a device and probe for a new driver
823 * @dev: the device to reprobe
825 * This function detaches the attached driver (if any) for the given
826 * device and restarts the driver probing process. It is intended
827 * to use if probing criteria changed during a devices lifetime and
828 * driver attachment should change accordingly.
830 int device_reprobe(struct device *dev)
833 if (dev->parent) /* Needed for USB */
834 device_lock(dev->parent);
835 device_release_driver(dev);
837 device_unlock(dev->parent);
839 return bus_rescan_devices_helper(dev, NULL);
841 EXPORT_SYMBOL_GPL(device_reprobe);
844 * find_bus - locate bus by name.
845 * @name: name of bus.
847 * Call kset_find_obj() to iterate over list of buses to
848 * find a bus by name. Return bus if found.
850 * Note that kset_find_obj increments bus' reference count.
853 struct bus_type *find_bus(char *name)
855 struct kobject *k = kset_find_obj(bus_kset, name);
856 return k ? to_bus(k) : NULL;
862 * bus_add_attrs - Add default attributes for this bus.
863 * @bus: Bus that has just been registered.
866 static int bus_add_attrs(struct bus_type *bus)
871 if (bus->bus_attrs) {
872 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
873 error = bus_create_file(bus, &bus->bus_attrs[i]);
882 bus_remove_file(bus, &bus->bus_attrs[i]);
886 static void bus_remove_attrs(struct bus_type *bus)
890 if (bus->bus_attrs) {
891 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
892 bus_remove_file(bus, &bus->bus_attrs[i]);
896 static void klist_devices_get(struct klist_node *n)
898 struct device_private *dev_prv = to_device_private_bus(n);
899 struct device *dev = dev_prv->device;
904 static void klist_devices_put(struct klist_node *n)
906 struct device_private *dev_prv = to_device_private_bus(n);
907 struct device *dev = dev_prv->device;
912 static ssize_t bus_uevent_store(struct bus_type *bus,
913 const char *buf, size_t count)
915 enum kobject_action action;
917 if (kobject_action_type(buf, count, &action) == 0)
918 kobject_uevent(&bus->p->subsys.kobj, action);
921 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
924 * __bus_register - register a driver-core subsystem
925 * @bus: bus to register
926 * @key: lockdep class key
928 * Once we have that, we register the bus with the kobject
929 * infrastructure, then register the children subsystems it has:
930 * the devices and drivers that belong to the subsystem.
932 int __bus_register(struct bus_type *bus, struct lock_class_key *key)
935 struct subsys_private *priv;
937 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
944 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
946 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
950 priv->subsys.kobj.kset = bus_kset;
951 priv->subsys.kobj.ktype = &bus_ktype;
952 priv->drivers_autoprobe = 1;
954 retval = kset_register(&priv->subsys);
958 retval = bus_create_file(bus, &bus_attr_uevent);
960 goto bus_uevent_fail;
962 priv->devices_kset = kset_create_and_add("devices", NULL,
964 if (!priv->devices_kset) {
966 goto bus_devices_fail;
969 priv->drivers_kset = kset_create_and_add("drivers", NULL,
971 if (!priv->drivers_kset) {
973 goto bus_drivers_fail;
976 INIT_LIST_HEAD(&priv->interfaces);
977 __mutex_init(&priv->mutex, "subsys mutex", key);
978 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
979 klist_init(&priv->klist_drivers, NULL, NULL);
981 retval = add_probe_files(bus);
983 goto bus_probe_files_fail;
985 retval = bus_add_attrs(bus);
989 pr_debug("bus: '%s': registered\n", bus->name);
993 remove_probe_files(bus);
994 bus_probe_files_fail:
995 kset_unregister(bus->p->drivers_kset);
997 kset_unregister(bus->p->devices_kset);
999 bus_remove_file(bus, &bus_attr_uevent);
1001 kset_unregister(&bus->p->subsys);
1007 EXPORT_SYMBOL_GPL(__bus_register);
1010 * bus_unregister - remove a bus from the system
1013 * Unregister the child subsystems and the bus itself.
1014 * Finally, we call bus_put() to release the refcount
1016 void bus_unregister(struct bus_type *bus)
1018 pr_debug("bus: '%s': unregistering\n", bus->name);
1020 device_unregister(bus->dev_root);
1021 bus_remove_attrs(bus);
1022 remove_probe_files(bus);
1023 kset_unregister(bus->p->drivers_kset);
1024 kset_unregister(bus->p->devices_kset);
1025 bus_remove_file(bus, &bus_attr_uevent);
1026 kset_unregister(&bus->p->subsys);
1030 EXPORT_SYMBOL_GPL(bus_unregister);
1032 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
1034 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
1036 EXPORT_SYMBOL_GPL(bus_register_notifier);
1038 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
1040 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
1042 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
1044 struct kset *bus_get_kset(struct bus_type *bus)
1046 return &bus->p->subsys;
1048 EXPORT_SYMBOL_GPL(bus_get_kset);
1050 struct klist *bus_get_device_klist(struct bus_type *bus)
1052 return &bus->p->klist_devices;
1054 EXPORT_SYMBOL_GPL(bus_get_device_klist);
1057 * Yes, this forcibly breaks the klist abstraction temporarily. It
1058 * just wants to sort the klist, not change reference counts and
1059 * take/drop locks rapidly in the process. It does all this while
1060 * holding the lock for the list, so objects can't otherwise be
1061 * added/removed while we're swizzling.
1063 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1064 int (*compare)(const struct device *a,
1065 const struct device *b))
1067 struct list_head *pos;
1068 struct klist_node *n;
1069 struct device_private *dev_prv;
1072 list_for_each(pos, list) {
1073 n = container_of(pos, struct klist_node, n_node);
1074 dev_prv = to_device_private_bus(n);
1075 b = dev_prv->device;
1076 if (compare(a, b) <= 0) {
1077 list_move_tail(&a->p->knode_bus.n_node,
1078 &b->p->knode_bus.n_node);
1082 list_move_tail(&a->p->knode_bus.n_node, list);
1085 void bus_sort_breadthfirst(struct bus_type *bus,
1086 int (*compare)(const struct device *a,
1087 const struct device *b))
1089 LIST_HEAD(sorted_devices);
1090 struct list_head *pos, *tmp;
1091 struct klist_node *n;
1092 struct device_private *dev_prv;
1094 struct klist *device_klist;
1096 device_klist = bus_get_device_klist(bus);
1098 spin_lock(&device_klist->k_lock);
1099 list_for_each_safe(pos, tmp, &device_klist->k_list) {
1100 n = container_of(pos, struct klist_node, n_node);
1101 dev_prv = to_device_private_bus(n);
1102 dev = dev_prv->device;
1103 device_insertion_sort_klist(dev, &sorted_devices, compare);
1105 list_splice(&sorted_devices, &device_klist->k_list);
1106 spin_unlock(&device_klist->k_lock);
1108 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1111 * subsys_dev_iter_init - initialize subsys device iterator
1112 * @iter: subsys iterator to initialize
1113 * @subsys: the subsys we wanna iterate over
1114 * @start: the device to start iterating from, if any
1115 * @type: device_type of the devices to iterate over, NULL for all
1117 * Initialize subsys iterator @iter such that it iterates over devices
1118 * of @subsys. If @start is set, the list iteration will start there,
1119 * otherwise if it is NULL, the iteration starts at the beginning of
1122 int subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1123 struct device *start, const struct device_type *type)
1125 struct klist_node *start_knode = NULL;
1129 start_knode = &start->p->knode_bus;
1130 error = klist_iter_init_node(&subsys->p->klist_devices, &iter->ki,
1136 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1139 * subsys_dev_iter_next - iterate to the next device
1140 * @iter: subsys iterator to proceed
1142 * Proceed @iter to the next device and return it. Returns NULL if
1143 * iteration is complete.
1145 * The returned device is referenced and won't be released till
1146 * iterator is proceed to the next device or exited. The caller is
1147 * free to do whatever it wants to do with the device including
1148 * calling back into subsys code.
1150 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1152 struct klist_node *knode;
1156 knode = klist_next(&iter->ki);
1159 dev = container_of(knode, struct device_private, knode_bus)->device;
1160 if (!iter->type || iter->type == dev->type)
1164 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1167 * subsys_dev_iter_exit - finish iteration
1168 * @iter: subsys iterator to finish
1170 * Finish an iteration. Always call this function after iteration is
1171 * complete whether the iteration ran till the end or not.
1173 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1175 klist_iter_exit(&iter->ki);
1177 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1179 int subsys_interface_register(struct subsys_interface *sif)
1181 struct bus_type *subsys;
1182 struct subsys_dev_iter iter;
1185 if (!sif || !sif->subsys)
1188 subsys = bus_get(sif->subsys);
1192 mutex_lock(&subsys->p->mutex);
1193 list_add_tail(&sif->node, &subsys->p->interfaces);
1195 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1196 while ((dev = subsys_dev_iter_next(&iter)))
1197 sif->add_dev(dev, sif);
1198 subsys_dev_iter_exit(&iter);
1200 mutex_unlock(&subsys->p->mutex);
1204 EXPORT_SYMBOL_GPL(subsys_interface_register);
1206 void subsys_interface_unregister(struct subsys_interface *sif)
1208 struct bus_type *subsys;
1209 struct subsys_dev_iter iter;
1212 if (!sif || !sif->subsys)
1215 subsys = sif->subsys;
1217 mutex_lock(&subsys->p->mutex);
1218 list_del_init(&sif->node);
1219 if (sif->remove_dev) {
1220 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1221 while ((dev = subsys_dev_iter_next(&iter)))
1222 sif->remove_dev(dev, sif);
1223 subsys_dev_iter_exit(&iter);
1225 mutex_unlock(&subsys->p->mutex);
1229 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1231 static void system_root_device_release(struct device *dev)
1236 * subsys_system_register - register a subsystem at /sys/devices/system/
1237 * @subsys: system subsystem
1238 * @groups: default attributes for the root device
1240 * All 'system' subsystems have a /sys/devices/system/<name> root device
1241 * with the name of the subsystem. The root device can carry subsystem-
1242 * wide attributes. All registered devices are below this single root
1243 * device and are named after the subsystem with a simple enumeration
1244 * number appended. The registered devices are not explicitely named;
1245 * only 'id' in the device needs to be set.
1247 * Do not use this interface for anything new, it exists for compatibility
1248 * with bad ideas only. New subsystems should use plain subsystems; and
1249 * add the subsystem-wide attributes should be added to the subsystem
1250 * directory itself and not some create fake root-device placed in
1251 * /sys/devices/system/<name>.
1253 int subsys_system_register(struct bus_type *subsys,
1254 const struct attribute_group **groups)
1259 err = bus_register(subsys);
1263 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1269 err = dev_set_name(dev, "%s", subsys->name);
1273 dev->kobj.parent = &system_kset->kobj;
1274 dev->groups = groups;
1275 dev->release = system_root_device_release;
1277 err = device_register(dev);
1281 subsys->dev_root = dev;
1290 bus_unregister(subsys);
1293 EXPORT_SYMBOL_GPL(subsys_system_register);
1295 int __init buses_init(void)
1297 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1301 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);