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;
167 /* Manually detach a device from its associated driver. */
168 static ssize_t driver_unbind(struct device_driver *drv,
169 const char *buf, size_t count)
171 struct bus_type *bus = bus_get(drv->bus);
175 dev = bus_find_device_by_name(bus, NULL, buf);
176 if (dev && dev->driver == drv) {
177 if (dev->parent) /* Needed for USB */
178 device_lock(dev->parent);
179 device_release_driver(dev);
181 device_unlock(dev->parent);
188 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
191 * Manually attach a device to a driver.
192 * Note: the driver must want to bind to the device,
193 * it is not possible to override the driver's id table.
195 static ssize_t driver_bind(struct device_driver *drv,
196 const char *buf, size_t count)
198 struct bus_type *bus = bus_get(drv->bus);
202 dev = bus_find_device_by_name(bus, NULL, buf);
203 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
204 if (dev->parent) /* Needed for USB */
205 device_lock(dev->parent);
207 err = driver_probe_device(drv, dev);
210 device_unlock(dev->parent);
215 } else if (err == 0) {
216 /* driver didn't accept device */
224 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
226 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
228 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
231 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
232 const char *buf, size_t count)
235 bus->p->drivers_autoprobe = 0;
237 bus->p->drivers_autoprobe = 1;
241 static ssize_t store_drivers_probe(struct bus_type *bus,
242 const char *buf, size_t count)
247 dev = bus_find_device_by_name(bus, NULL, buf);
250 if (bus_rescan_devices_helper(dev, NULL) == 0)
256 static struct device *next_device(struct klist_iter *i)
258 struct klist_node *n = klist_next(i);
259 struct device *dev = NULL;
260 struct device_private *dev_prv;
263 dev_prv = to_device_private_bus(n);
264 dev = dev_prv->device;
270 * bus_for_each_dev - device iterator.
272 * @start: device to start iterating from.
273 * @data: data for the callback.
274 * @fn: function to be called for each device.
276 * Iterate over @bus's list of devices, and call @fn for each,
277 * passing it @data. If @start is not NULL, we use that device to
278 * begin iterating from.
280 * We check the return of @fn each time. If it returns anything
281 * other than 0, we break out and return that value.
283 * NOTE: The device that returns a non-zero value is not retained
284 * in any way, nor is its refcount incremented. If the caller needs
285 * to retain this data, it should do so, and increment the reference
286 * count in the supplied callback.
288 int bus_for_each_dev(struct bus_type *bus, struct device *start,
289 void *data, int (*fn)(struct device *, void *))
298 klist_iter_init_node(&bus->p->klist_devices, &i,
299 (start ? &start->p->knode_bus : NULL));
300 while ((dev = next_device(&i)) && !error)
301 error = fn(dev, data);
305 EXPORT_SYMBOL_GPL(bus_for_each_dev);
308 * bus_find_device - device iterator for locating a particular device.
310 * @start: Device to begin with
311 * @data: Data to pass to match function
312 * @match: Callback function to check device
314 * This is similar to the bus_for_each_dev() function above, but it
315 * returns a reference to a device that is 'found' for later use, as
316 * determined by the @match callback.
318 * The callback should return 0 if the device doesn't match and non-zero
319 * if it does. If the callback returns non-zero, this function will
320 * return to the caller and not iterate over any more devices.
322 struct device *bus_find_device(struct bus_type *bus,
323 struct device *start, void *data,
324 int (*match)(struct device *dev, void *data))
332 klist_iter_init_node(&bus->p->klist_devices, &i,
333 (start ? &start->p->knode_bus : NULL));
334 while ((dev = next_device(&i)))
335 if (match(dev, data) && get_device(dev))
340 EXPORT_SYMBOL_GPL(bus_find_device);
342 static int match_name(struct device *dev, void *data)
344 const char *name = data;
346 return sysfs_streq(name, dev_name(dev));
350 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
352 * @start: Device to begin with
353 * @name: name of the device to match
355 * This is similar to the bus_find_device() function above, but it handles
356 * searching by a name automatically, no need to write another strcmp matching
359 struct device *bus_find_device_by_name(struct bus_type *bus,
360 struct device *start, const char *name)
362 return bus_find_device(bus, start, (void *)name, match_name);
364 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
367 * subsys_find_device_by_id - find a device with a specific enumeration number
369 * @id: index 'id' in struct device
370 * @hint: device to check first
372 * Check the hint's next object and if it is a match return it directly,
373 * otherwise, fall back to a full list search. Either way a reference for
374 * the returned object is taken.
376 struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
386 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
387 dev = next_device(&i);
388 if (dev && dev->id == id && get_device(dev)) {
395 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
396 while ((dev = next_device(&i))) {
397 if (dev->id == id && get_device(dev)) {
405 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
407 static struct device_driver *next_driver(struct klist_iter *i)
409 struct klist_node *n = klist_next(i);
410 struct driver_private *drv_priv;
413 drv_priv = container_of(n, struct driver_private, knode_bus);
414 return drv_priv->driver;
420 * bus_for_each_drv - driver iterator
421 * @bus: bus we're dealing with.
422 * @start: driver to start iterating on.
423 * @data: data to pass to the callback.
424 * @fn: function to call for each driver.
426 * This is nearly identical to the device iterator above.
427 * We iterate over each driver that belongs to @bus, and call
428 * @fn for each. If @fn returns anything but 0, we break out
429 * and return it. If @start is not NULL, we use it as the head
432 * NOTE: we don't return the driver that returns a non-zero
433 * value, nor do we leave the reference count incremented for that
434 * driver. If the caller needs to know that info, it must set it
435 * in the callback. It must also be sure to increment the refcount
436 * so it doesn't disappear before returning to the caller.
438 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
439 void *data, int (*fn)(struct device_driver *, void *))
442 struct device_driver *drv;
448 klist_iter_init_node(&bus->p->klist_drivers, &i,
449 start ? &start->p->knode_bus : NULL);
450 while ((drv = next_driver(&i)) && !error)
451 error = fn(drv, data);
455 EXPORT_SYMBOL_GPL(bus_for_each_drv);
457 static int device_add_attrs(struct bus_type *bus, struct device *dev)
465 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
466 error = device_create_file(dev, &bus->dev_attrs[i]);
469 device_remove_file(dev, &bus->dev_attrs[i]);
476 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
480 if (bus->dev_attrs) {
481 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
482 device_remove_file(dev, &bus->dev_attrs[i]);
487 * bus_add_device - add device to bus
488 * @dev: device being added
490 * - Add device's bus attributes.
491 * - Create links to device's bus.
492 * - Add the device to its bus's list of devices.
494 int bus_add_device(struct device *dev)
496 struct bus_type *bus = bus_get(dev->bus);
500 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
501 error = device_add_attrs(bus, dev);
504 error = sysfs_create_link(&bus->p->devices_kset->kobj,
505 &dev->kobj, dev_name(dev));
508 error = sysfs_create_link(&dev->kobj,
509 &dev->bus->p->subsys.kobj, "subsystem");
512 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
517 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
519 device_remove_attrs(bus, dev);
526 * bus_probe_device - probe drivers for a new device
527 * @dev: device to probe
529 * - Automatically probe for a driver if the bus allows it.
531 void bus_probe_device(struct device *dev)
533 struct bus_type *bus = dev->bus;
534 struct subsys_interface *sif;
540 if (bus->p->drivers_autoprobe) {
541 ret = device_attach(dev);
545 mutex_lock(&bus->p->mutex);
546 list_for_each_entry(sif, &bus->p->interfaces, node)
548 sif->add_dev(dev, sif);
549 mutex_unlock(&bus->p->mutex);
553 * bus_remove_device - remove device from bus
554 * @dev: device to be removed
556 * - Remove device from all interfaces.
557 * - Remove symlink from bus' directory.
558 * - Delete device from bus's list.
559 * - Detach from its driver.
560 * - Drop reference taken in bus_add_device().
562 void bus_remove_device(struct device *dev)
564 struct bus_type *bus = dev->bus;
565 struct subsys_interface *sif;
570 mutex_lock(&bus->p->mutex);
571 list_for_each_entry(sif, &bus->p->interfaces, node)
573 sif->remove_dev(dev, sif);
574 mutex_unlock(&bus->p->mutex);
576 sysfs_remove_link(&dev->kobj, "subsystem");
577 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
579 device_remove_attrs(dev->bus, dev);
580 if (klist_node_attached(&dev->p->knode_bus))
581 klist_del(&dev->p->knode_bus);
583 pr_debug("bus: '%s': remove device %s\n",
584 dev->bus->name, dev_name(dev));
585 device_release_driver(dev);
589 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
594 if (bus->drv_attrs) {
595 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
596 error = driver_create_file(drv, &bus->drv_attrs[i]);
605 driver_remove_file(drv, &bus->drv_attrs[i]);
609 static void driver_remove_attrs(struct bus_type *bus,
610 struct device_driver *drv)
614 if (bus->drv_attrs) {
615 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
616 driver_remove_file(drv, &bus->drv_attrs[i]);
620 static int __must_check add_bind_files(struct device_driver *drv)
624 ret = driver_create_file(drv, &driver_attr_unbind);
626 ret = driver_create_file(drv, &driver_attr_bind);
628 driver_remove_file(drv, &driver_attr_unbind);
633 static void remove_bind_files(struct device_driver *drv)
635 driver_remove_file(drv, &driver_attr_bind);
636 driver_remove_file(drv, &driver_attr_unbind);
639 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
640 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
641 show_drivers_autoprobe, store_drivers_autoprobe);
643 static int add_probe_files(struct bus_type *bus)
647 retval = bus_create_file(bus, &bus_attr_drivers_probe);
651 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
653 bus_remove_file(bus, &bus_attr_drivers_probe);
658 static void remove_probe_files(struct bus_type *bus)
660 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
661 bus_remove_file(bus, &bus_attr_drivers_probe);
664 static ssize_t driver_uevent_store(struct device_driver *drv,
665 const char *buf, size_t count)
667 enum kobject_action action;
669 if (kobject_action_type(buf, count, &action) == 0)
670 kobject_uevent(&drv->p->kobj, action);
673 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
676 * bus_add_driver - Add a driver to the bus.
679 int bus_add_driver(struct device_driver *drv)
681 struct bus_type *bus;
682 struct driver_private *priv;
685 bus = bus_get(drv->bus);
689 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
691 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
696 klist_init(&priv->klist_devices, NULL, NULL);
699 priv->kobj.kset = bus->p->drivers_kset;
700 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
705 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
706 if (drv->bus->p->drivers_autoprobe) {
707 error = driver_attach(drv);
711 module_add_driver(drv->owner, drv);
713 error = driver_create_file(drv, &driver_attr_uevent);
715 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
716 __func__, drv->name);
718 error = driver_add_attrs(bus, drv);
720 /* How the hell do we get out of this pickle? Give up */
721 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
722 __func__, drv->name);
725 if (!drv->suppress_bind_attrs) {
726 error = add_bind_files(drv);
729 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
730 __func__, drv->name);
737 kobject_put(&priv->kobj);
746 * bus_remove_driver - delete driver from bus's knowledge.
749 * Detach the driver from the devices it controls, and remove
750 * it from its bus's list of drivers. Finally, we drop the reference
751 * to the bus we took in bus_add_driver().
753 void bus_remove_driver(struct device_driver *drv)
758 if (!drv->suppress_bind_attrs)
759 remove_bind_files(drv);
760 driver_remove_attrs(drv->bus, drv);
761 driver_remove_file(drv, &driver_attr_uevent);
762 klist_remove(&drv->p->knode_bus);
763 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
765 module_remove_driver(drv);
766 kobject_put(&drv->p->kobj);
770 /* Helper for bus_rescan_devices's iter */
771 static int __must_check bus_rescan_devices_helper(struct device *dev,
777 if (dev->parent) /* Needed for USB */
778 device_lock(dev->parent);
779 ret = device_attach(dev);
781 device_unlock(dev->parent);
783 return ret < 0 ? ret : 0;
787 * bus_rescan_devices - rescan devices on the bus for possible drivers
788 * @bus: the bus to scan.
790 * This function will look for devices on the bus with no driver
791 * attached and rescan it against existing drivers to see if it matches
792 * any by calling device_attach() for the unbound devices.
794 int bus_rescan_devices(struct bus_type *bus)
796 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
798 EXPORT_SYMBOL_GPL(bus_rescan_devices);
801 * device_reprobe - remove driver for a device and probe for a new driver
802 * @dev: the device to reprobe
804 * This function detaches the attached driver (if any) for the given
805 * device and restarts the driver probing process. It is intended
806 * to use if probing criteria changed during a devices lifetime and
807 * driver attachment should change accordingly.
809 int device_reprobe(struct device *dev)
812 if (dev->parent) /* Needed for USB */
813 device_lock(dev->parent);
814 device_release_driver(dev);
816 device_unlock(dev->parent);
818 return bus_rescan_devices_helper(dev, NULL);
820 EXPORT_SYMBOL_GPL(device_reprobe);
823 * find_bus - locate bus by name.
824 * @name: name of bus.
826 * Call kset_find_obj() to iterate over list of buses to
827 * find a bus by name. Return bus if found.
829 * Note that kset_find_obj increments bus' reference count.
832 struct bus_type *find_bus(char *name)
834 struct kobject *k = kset_find_obj(bus_kset, name);
835 return k ? to_bus(k) : NULL;
841 * bus_add_attrs - Add default attributes for this bus.
842 * @bus: Bus that has just been registered.
845 static int bus_add_attrs(struct bus_type *bus)
850 if (bus->bus_attrs) {
851 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
852 error = bus_create_file(bus, &bus->bus_attrs[i]);
861 bus_remove_file(bus, &bus->bus_attrs[i]);
865 static void bus_remove_attrs(struct bus_type *bus)
869 if (bus->bus_attrs) {
870 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
871 bus_remove_file(bus, &bus->bus_attrs[i]);
875 static void klist_devices_get(struct klist_node *n)
877 struct device_private *dev_prv = to_device_private_bus(n);
878 struct device *dev = dev_prv->device;
883 static void klist_devices_put(struct klist_node *n)
885 struct device_private *dev_prv = to_device_private_bus(n);
886 struct device *dev = dev_prv->device;
891 static ssize_t bus_uevent_store(struct bus_type *bus,
892 const char *buf, size_t count)
894 enum kobject_action action;
896 if (kobject_action_type(buf, count, &action) == 0)
897 kobject_uevent(&bus->p->subsys.kobj, action);
900 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
903 * bus_register - register a driver-core subsystem
904 * @bus: bus to register
906 * Once we have that, we register the bus with the kobject
907 * infrastructure, then register the children subsystems it has:
908 * the devices and drivers that belong to the subsystem.
910 int bus_register(struct bus_type *bus)
913 struct subsys_private *priv;
914 struct lock_class_key *key = &bus->lock_key;
916 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
923 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
925 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
929 priv->subsys.kobj.kset = bus_kset;
930 priv->subsys.kobj.ktype = &bus_ktype;
931 priv->drivers_autoprobe = 1;
933 retval = kset_register(&priv->subsys);
937 retval = bus_create_file(bus, &bus_attr_uevent);
939 goto bus_uevent_fail;
941 priv->devices_kset = kset_create_and_add("devices", NULL,
943 if (!priv->devices_kset) {
945 goto bus_devices_fail;
948 priv->drivers_kset = kset_create_and_add("drivers", NULL,
950 if (!priv->drivers_kset) {
952 goto bus_drivers_fail;
955 INIT_LIST_HEAD(&priv->interfaces);
956 __mutex_init(&priv->mutex, "subsys mutex", key);
957 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
958 klist_init(&priv->klist_drivers, NULL, NULL);
960 retval = add_probe_files(bus);
962 goto bus_probe_files_fail;
964 retval = bus_add_attrs(bus);
968 pr_debug("bus: '%s': registered\n", bus->name);
972 remove_probe_files(bus);
973 bus_probe_files_fail:
974 kset_unregister(bus->p->drivers_kset);
976 kset_unregister(bus->p->devices_kset);
978 bus_remove_file(bus, &bus_attr_uevent);
980 kset_unregister(&bus->p->subsys);
986 EXPORT_SYMBOL_GPL(bus_register);
989 * bus_unregister - remove a bus from the system
992 * Unregister the child subsystems and the bus itself.
993 * Finally, we call bus_put() to release the refcount
995 void bus_unregister(struct bus_type *bus)
997 pr_debug("bus: '%s': unregistering\n", bus->name);
999 device_unregister(bus->dev_root);
1000 bus_remove_attrs(bus);
1001 remove_probe_files(bus);
1002 kset_unregister(bus->p->drivers_kset);
1003 kset_unregister(bus->p->devices_kset);
1004 bus_remove_file(bus, &bus_attr_uevent);
1005 kset_unregister(&bus->p->subsys);
1009 EXPORT_SYMBOL_GPL(bus_unregister);
1011 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
1013 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
1015 EXPORT_SYMBOL_GPL(bus_register_notifier);
1017 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
1019 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
1021 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
1023 struct kset *bus_get_kset(struct bus_type *bus)
1025 return &bus->p->subsys;
1027 EXPORT_SYMBOL_GPL(bus_get_kset);
1029 struct klist *bus_get_device_klist(struct bus_type *bus)
1031 return &bus->p->klist_devices;
1033 EXPORT_SYMBOL_GPL(bus_get_device_klist);
1036 * Yes, this forcibly breaks the klist abstraction temporarily. It
1037 * just wants to sort the klist, not change reference counts and
1038 * take/drop locks rapidly in the process. It does all this while
1039 * holding the lock for the list, so objects can't otherwise be
1040 * added/removed while we're swizzling.
1042 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1043 int (*compare)(const struct device *a,
1044 const struct device *b))
1046 struct list_head *pos;
1047 struct klist_node *n;
1048 struct device_private *dev_prv;
1051 list_for_each(pos, list) {
1052 n = container_of(pos, struct klist_node, n_node);
1053 dev_prv = to_device_private_bus(n);
1054 b = dev_prv->device;
1055 if (compare(a, b) <= 0) {
1056 list_move_tail(&a->p->knode_bus.n_node,
1057 &b->p->knode_bus.n_node);
1061 list_move_tail(&a->p->knode_bus.n_node, list);
1064 void bus_sort_breadthfirst(struct bus_type *bus,
1065 int (*compare)(const struct device *a,
1066 const struct device *b))
1068 LIST_HEAD(sorted_devices);
1069 struct list_head *pos, *tmp;
1070 struct klist_node *n;
1071 struct device_private *dev_prv;
1073 struct klist *device_klist;
1075 device_klist = bus_get_device_klist(bus);
1077 spin_lock(&device_klist->k_lock);
1078 list_for_each_safe(pos, tmp, &device_klist->k_list) {
1079 n = container_of(pos, struct klist_node, n_node);
1080 dev_prv = to_device_private_bus(n);
1081 dev = dev_prv->device;
1082 device_insertion_sort_klist(dev, &sorted_devices, compare);
1084 list_splice(&sorted_devices, &device_klist->k_list);
1085 spin_unlock(&device_klist->k_lock);
1087 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1090 * subsys_dev_iter_init - initialize subsys device iterator
1091 * @iter: subsys iterator to initialize
1092 * @subsys: the subsys we wanna iterate over
1093 * @start: the device to start iterating from, if any
1094 * @type: device_type of the devices to iterate over, NULL for all
1096 * Initialize subsys iterator @iter such that it iterates over devices
1097 * of @subsys. If @start is set, the list iteration will start there,
1098 * otherwise if it is NULL, the iteration starts at the beginning of
1101 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1102 struct device *start, const struct device_type *type)
1104 struct klist_node *start_knode = NULL;
1107 start_knode = &start->p->knode_bus;
1108 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1111 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1114 * subsys_dev_iter_next - iterate to the next device
1115 * @iter: subsys iterator to proceed
1117 * Proceed @iter to the next device and return it. Returns NULL if
1118 * iteration is complete.
1120 * The returned device is referenced and won't be released till
1121 * iterator is proceed to the next device or exited. The caller is
1122 * free to do whatever it wants to do with the device including
1123 * calling back into subsys code.
1125 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1127 struct klist_node *knode;
1131 knode = klist_next(&iter->ki);
1134 dev = container_of(knode, struct device_private, knode_bus)->device;
1135 if (!iter->type || iter->type == dev->type)
1139 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1142 * subsys_dev_iter_exit - finish iteration
1143 * @iter: subsys iterator to finish
1145 * Finish an iteration. Always call this function after iteration is
1146 * complete whether the iteration ran till the end or not.
1148 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1150 klist_iter_exit(&iter->ki);
1152 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1154 int subsys_interface_register(struct subsys_interface *sif)
1156 struct bus_type *subsys;
1157 struct subsys_dev_iter iter;
1160 if (!sif || !sif->subsys)
1163 subsys = bus_get(sif->subsys);
1167 mutex_lock(&subsys->p->mutex);
1168 list_add_tail(&sif->node, &subsys->p->interfaces);
1170 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1171 while ((dev = subsys_dev_iter_next(&iter)))
1172 sif->add_dev(dev, sif);
1173 subsys_dev_iter_exit(&iter);
1175 mutex_unlock(&subsys->p->mutex);
1179 EXPORT_SYMBOL_GPL(subsys_interface_register);
1181 void subsys_interface_unregister(struct subsys_interface *sif)
1183 struct bus_type *subsys;
1184 struct subsys_dev_iter iter;
1187 if (!sif || !sif->subsys)
1190 subsys = sif->subsys;
1192 mutex_lock(&subsys->p->mutex);
1193 list_del_init(&sif->node);
1194 if (sif->remove_dev) {
1195 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1196 while ((dev = subsys_dev_iter_next(&iter)))
1197 sif->remove_dev(dev, sif);
1198 subsys_dev_iter_exit(&iter);
1200 mutex_unlock(&subsys->p->mutex);
1204 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1206 static void system_root_device_release(struct device *dev)
1211 static int subsys_register(struct bus_type *subsys,
1212 const struct attribute_group **groups,
1213 struct kobject *parent_of_root)
1218 err = bus_register(subsys);
1222 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1228 err = dev_set_name(dev, "%s", subsys->name);
1232 dev->kobj.parent = parent_of_root;
1233 dev->groups = groups;
1234 dev->release = system_root_device_release;
1236 err = device_register(dev);
1240 subsys->dev_root = dev;
1249 bus_unregister(subsys);
1254 * subsys_system_register - register a subsystem at /sys/devices/system/
1255 * @subsys: system subsystem
1256 * @groups: default attributes for the root device
1258 * All 'system' subsystems have a /sys/devices/system/<name> root device
1259 * with the name of the subsystem. The root device can carry subsystem-
1260 * wide attributes. All registered devices are below this single root
1261 * device and are named after the subsystem with a simple enumeration
1262 * number appended. The registered devices are not explicitely named;
1263 * only 'id' in the device needs to be set.
1265 * Do not use this interface for anything new, it exists for compatibility
1266 * with bad ideas only. New subsystems should use plain subsystems; and
1267 * add the subsystem-wide attributes should be added to the subsystem
1268 * directory itself and not some create fake root-device placed in
1269 * /sys/devices/system/<name>.
1271 int subsys_system_register(struct bus_type *subsys,
1272 const struct attribute_group **groups)
1274 return subsys_register(subsys, groups, &system_kset->kobj);
1276 EXPORT_SYMBOL_GPL(subsys_system_register);
1279 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1280 * @subsys: virtual subsystem
1281 * @groups: default attributes for the root device
1283 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1284 * with the name of the subystem. The root device can carry subsystem-wide
1285 * attributes. All registered devices are below this single root device.
1286 * There's no restriction on device naming. This is for kernel software
1287 * constructs which need sysfs interface.
1289 int subsys_virtual_register(struct bus_type *subsys,
1290 const struct attribute_group **groups)
1292 struct kobject *virtual_dir;
1294 virtual_dir = virtual_device_parent(NULL);
1298 return subsys_register(subsys, groups, virtual_dir);
1300 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1302 int __init buses_init(void)
1304 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1308 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);