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
);
473 * bus_add_device - add device to bus
474 * @dev: device being added
476 * - Add device's bus attributes.
477 * - Create links to device's bus.
478 * - Add the device to its bus's list of devices.
480 int bus_add_device(struct device
*dev
)
482 struct bus_type
*bus
= bus_get(dev
->bus
);
486 pr_debug("bus: '%s': add device %s\n", bus
->name
, dev_name(dev
));
487 error
= device_add_groups(dev
, bus
->dev_groups
);
490 error
= sysfs_create_link(&bus
->p
->devices_kset
->kobj
,
491 &dev
->kobj
, dev_name(dev
));
494 error
= sysfs_create_link(&dev
->kobj
,
495 &dev
->bus
->p
->subsys
.kobj
, "subsystem");
498 klist_add_tail(&dev
->p
->knode_bus
, &bus
->p
->klist_devices
);
503 sysfs_remove_link(&bus
->p
->devices_kset
->kobj
, dev_name(dev
));
505 device_remove_groups(dev
, bus
->dev_groups
);
512 * bus_probe_device - probe drivers for a new device
513 * @dev: device to probe
515 * - Automatically probe for a driver if the bus allows it.
517 void bus_probe_device(struct device
*dev
)
519 struct bus_type
*bus
= dev
->bus
;
520 struct subsys_interface
*sif
;
525 if (bus
->p
->drivers_autoprobe
)
526 device_initial_probe(dev
);
528 mutex_lock(&bus
->p
->mutex
);
529 list_for_each_entry(sif
, &bus
->p
->interfaces
, node
)
531 sif
->add_dev(dev
, sif
);
532 mutex_unlock(&bus
->p
->mutex
);
536 * bus_remove_device - remove device from bus
537 * @dev: device to be removed
539 * - Remove device from all interfaces.
540 * - Remove symlink from bus' directory.
541 * - Delete device from bus's list.
542 * - Detach from its driver.
543 * - Drop reference taken in bus_add_device().
545 void bus_remove_device(struct device
*dev
)
547 struct bus_type
*bus
= dev
->bus
;
548 struct subsys_interface
*sif
;
553 mutex_lock(&bus
->p
->mutex
);
554 list_for_each_entry(sif
, &bus
->p
->interfaces
, node
)
556 sif
->remove_dev(dev
, sif
);
557 mutex_unlock(&bus
->p
->mutex
);
559 sysfs_remove_link(&dev
->kobj
, "subsystem");
560 sysfs_remove_link(&dev
->bus
->p
->devices_kset
->kobj
,
562 device_remove_groups(dev
, dev
->bus
->dev_groups
);
563 if (klist_node_attached(&dev
->p
->knode_bus
))
564 klist_del(&dev
->p
->knode_bus
);
566 pr_debug("bus: '%s': remove device %s\n",
567 dev
->bus
->name
, dev_name(dev
));
568 device_release_driver(dev
);
572 static int __must_check
add_bind_files(struct device_driver
*drv
)
576 ret
= driver_create_file(drv
, &driver_attr_unbind
);
578 ret
= driver_create_file(drv
, &driver_attr_bind
);
580 driver_remove_file(drv
, &driver_attr_unbind
);
585 static void remove_bind_files(struct device_driver
*drv
)
587 driver_remove_file(drv
, &driver_attr_bind
);
588 driver_remove_file(drv
, &driver_attr_unbind
);
591 static BUS_ATTR(drivers_probe
, S_IWUSR
, NULL
, store_drivers_probe
);
592 static BUS_ATTR(drivers_autoprobe
, S_IWUSR
| S_IRUGO
,
593 show_drivers_autoprobe
, store_drivers_autoprobe
);
595 static int add_probe_files(struct bus_type
*bus
)
599 retval
= bus_create_file(bus
, &bus_attr_drivers_probe
);
603 retval
= bus_create_file(bus
, &bus_attr_drivers_autoprobe
);
605 bus_remove_file(bus
, &bus_attr_drivers_probe
);
610 static void remove_probe_files(struct bus_type
*bus
)
612 bus_remove_file(bus
, &bus_attr_drivers_autoprobe
);
613 bus_remove_file(bus
, &bus_attr_drivers_probe
);
616 static ssize_t
uevent_store(struct device_driver
*drv
, const char *buf
,
621 rc
= kobject_synth_uevent(&drv
->p
->kobj
, buf
, count
);
622 return rc
? rc
: count
;
624 static DRIVER_ATTR_WO(uevent
);
626 static void driver_attach_async(void *_drv
, async_cookie_t cookie
)
628 struct device_driver
*drv
= _drv
;
631 ret
= driver_attach(drv
);
633 pr_debug("bus: '%s': driver %s async attach completed: %d\n",
634 drv
->bus
->name
, drv
->name
, ret
);
638 * bus_add_driver - Add a driver to the bus.
641 int bus_add_driver(struct device_driver
*drv
)
643 struct bus_type
*bus
;
644 struct driver_private
*priv
;
647 bus
= bus_get(drv
->bus
);
651 pr_debug("bus: '%s': add driver %s\n", bus
->name
, drv
->name
);
653 priv
= kzalloc(sizeof(*priv
), GFP_KERNEL
);
658 klist_init(&priv
->klist_devices
, NULL
, NULL
);
661 priv
->kobj
.kset
= bus
->p
->drivers_kset
;
662 error
= kobject_init_and_add(&priv
->kobj
, &driver_ktype
, NULL
,
667 klist_add_tail(&priv
->knode_bus
, &bus
->p
->klist_drivers
);
668 if (drv
->bus
->p
->drivers_autoprobe
) {
669 if (driver_allows_async_probing(drv
)) {
670 pr_debug("bus: '%s': probing driver %s asynchronously\n",
671 drv
->bus
->name
, drv
->name
);
672 async_schedule(driver_attach_async
, drv
);
674 error
= driver_attach(drv
);
679 module_add_driver(drv
->owner
, drv
);
681 error
= driver_create_file(drv
, &driver_attr_uevent
);
683 printk(KERN_ERR
"%s: uevent attr (%s) failed\n",
684 __func__
, drv
->name
);
686 error
= driver_add_groups(drv
, bus
->drv_groups
);
688 /* How the hell do we get out of this pickle? Give up */
689 printk(KERN_ERR
"%s: driver_create_groups(%s) failed\n",
690 __func__
, drv
->name
);
693 if (!drv
->suppress_bind_attrs
) {
694 error
= add_bind_files(drv
);
697 printk(KERN_ERR
"%s: add_bind_files(%s) failed\n",
698 __func__
, drv
->name
);
705 kobject_put(&priv
->kobj
);
706 /* drv->p is freed in driver_release() */
714 * bus_remove_driver - delete driver from bus's knowledge.
717 * Detach the driver from the devices it controls, and remove
718 * it from its bus's list of drivers. Finally, we drop the reference
719 * to the bus we took in bus_add_driver().
721 void bus_remove_driver(struct device_driver
*drv
)
726 if (!drv
->suppress_bind_attrs
)
727 remove_bind_files(drv
);
728 driver_remove_groups(drv
, drv
->bus
->drv_groups
);
729 driver_remove_file(drv
, &driver_attr_uevent
);
730 klist_remove(&drv
->p
->knode_bus
);
731 pr_debug("bus: '%s': remove driver %s\n", drv
->bus
->name
, drv
->name
);
733 module_remove_driver(drv
);
734 kobject_put(&drv
->p
->kobj
);
738 /* Helper for bus_rescan_devices's iter */
739 static int __must_check
bus_rescan_devices_helper(struct device
*dev
,
745 if (dev
->parent
) /* Needed for USB */
746 device_lock(dev
->parent
);
747 ret
= device_attach(dev
);
749 device_unlock(dev
->parent
);
751 return ret
< 0 ? ret
: 0;
755 * bus_rescan_devices - rescan devices on the bus for possible drivers
756 * @bus: the bus to scan.
758 * This function will look for devices on the bus with no driver
759 * attached and rescan it against existing drivers to see if it matches
760 * any by calling device_attach() for the unbound devices.
762 int bus_rescan_devices(struct bus_type
*bus
)
764 return bus_for_each_dev(bus
, NULL
, NULL
, bus_rescan_devices_helper
);
766 EXPORT_SYMBOL_GPL(bus_rescan_devices
);
769 * device_reprobe - remove driver for a device and probe for a new driver
770 * @dev: the device to reprobe
772 * This function detaches the attached driver (if any) for the given
773 * device and restarts the driver probing process. It is intended
774 * to use if probing criteria changed during a devices lifetime and
775 * driver attachment should change accordingly.
777 int device_reprobe(struct device
*dev
)
780 if (dev
->parent
) /* Needed for USB */
781 device_lock(dev
->parent
);
782 device_release_driver(dev
);
784 device_unlock(dev
->parent
);
786 return bus_rescan_devices_helper(dev
, NULL
);
788 EXPORT_SYMBOL_GPL(device_reprobe
);
791 * find_bus - locate bus by name.
792 * @name: name of bus.
794 * Call kset_find_obj() to iterate over list of buses to
795 * find a bus by name. Return bus if found.
797 * Note that kset_find_obj increments bus' reference count.
800 struct bus_type
*find_bus(char *name
)
802 struct kobject
*k
= kset_find_obj(bus_kset
, name
);
803 return k
? to_bus(k
) : NULL
;
807 static int bus_add_groups(struct bus_type
*bus
,
808 const struct attribute_group
**groups
)
810 return sysfs_create_groups(&bus
->p
->subsys
.kobj
, groups
);
813 static void bus_remove_groups(struct bus_type
*bus
,
814 const struct attribute_group
**groups
)
816 sysfs_remove_groups(&bus
->p
->subsys
.kobj
, groups
);
819 static void klist_devices_get(struct klist_node
*n
)
821 struct device_private
*dev_prv
= to_device_private_bus(n
);
822 struct device
*dev
= dev_prv
->device
;
827 static void klist_devices_put(struct klist_node
*n
)
829 struct device_private
*dev_prv
= to_device_private_bus(n
);
830 struct device
*dev
= dev_prv
->device
;
835 static ssize_t
bus_uevent_store(struct bus_type
*bus
,
836 const char *buf
, size_t count
)
840 rc
= kobject_synth_uevent(&bus
->p
->subsys
.kobj
, buf
, count
);
841 return rc
? rc
: count
;
843 static BUS_ATTR(uevent
, S_IWUSR
, NULL
, bus_uevent_store
);
846 * bus_register - register a driver-core subsystem
847 * @bus: bus to register
849 * Once we have that, we register the bus with the kobject
850 * infrastructure, then register the children subsystems it has:
851 * the devices and drivers that belong to the subsystem.
853 int bus_register(struct bus_type
*bus
)
856 struct subsys_private
*priv
;
857 struct lock_class_key
*key
= &bus
->lock_key
;
859 priv
= kzalloc(sizeof(struct subsys_private
), GFP_KERNEL
);
866 BLOCKING_INIT_NOTIFIER_HEAD(&priv
->bus_notifier
);
868 retval
= kobject_set_name(&priv
->subsys
.kobj
, "%s", bus
->name
);
872 priv
->subsys
.kobj
.kset
= bus_kset
;
873 priv
->subsys
.kobj
.ktype
= &bus_ktype
;
874 priv
->drivers_autoprobe
= 1;
876 retval
= kset_register(&priv
->subsys
);
880 retval
= bus_create_file(bus
, &bus_attr_uevent
);
882 goto bus_uevent_fail
;
884 priv
->devices_kset
= kset_create_and_add("devices", NULL
,
886 if (!priv
->devices_kset
) {
888 goto bus_devices_fail
;
891 priv
->drivers_kset
= kset_create_and_add("drivers", NULL
,
893 if (!priv
->drivers_kset
) {
895 goto bus_drivers_fail
;
898 INIT_LIST_HEAD(&priv
->interfaces
);
899 __mutex_init(&priv
->mutex
, "subsys mutex", key
);
900 klist_init(&priv
->klist_devices
, klist_devices_get
, klist_devices_put
);
901 klist_init(&priv
->klist_drivers
, NULL
, NULL
);
903 retval
= add_probe_files(bus
);
905 goto bus_probe_files_fail
;
907 retval
= bus_add_groups(bus
, bus
->bus_groups
);
909 goto bus_groups_fail
;
911 pr_debug("bus: '%s': registered\n", bus
->name
);
915 remove_probe_files(bus
);
916 bus_probe_files_fail
:
917 kset_unregister(bus
->p
->drivers_kset
);
919 kset_unregister(bus
->p
->devices_kset
);
921 bus_remove_file(bus
, &bus_attr_uevent
);
923 kset_unregister(&bus
->p
->subsys
);
929 EXPORT_SYMBOL_GPL(bus_register
);
932 * bus_unregister - remove a bus from the system
935 * Unregister the child subsystems and the bus itself.
936 * Finally, we call bus_put() to release the refcount
938 void bus_unregister(struct bus_type
*bus
)
940 pr_debug("bus: '%s': unregistering\n", bus
->name
);
942 device_unregister(bus
->dev_root
);
943 bus_remove_groups(bus
, bus
->bus_groups
);
944 remove_probe_files(bus
);
945 kset_unregister(bus
->p
->drivers_kset
);
946 kset_unregister(bus
->p
->devices_kset
);
947 bus_remove_file(bus
, &bus_attr_uevent
);
948 kset_unregister(&bus
->p
->subsys
);
950 EXPORT_SYMBOL_GPL(bus_unregister
);
952 int bus_register_notifier(struct bus_type
*bus
, struct notifier_block
*nb
)
954 return blocking_notifier_chain_register(&bus
->p
->bus_notifier
, nb
);
956 EXPORT_SYMBOL_GPL(bus_register_notifier
);
958 int bus_unregister_notifier(struct bus_type
*bus
, struct notifier_block
*nb
)
960 return blocking_notifier_chain_unregister(&bus
->p
->bus_notifier
, nb
);
962 EXPORT_SYMBOL_GPL(bus_unregister_notifier
);
964 struct kset
*bus_get_kset(struct bus_type
*bus
)
966 return &bus
->p
->subsys
;
968 EXPORT_SYMBOL_GPL(bus_get_kset
);
970 struct klist
*bus_get_device_klist(struct bus_type
*bus
)
972 return &bus
->p
->klist_devices
;
974 EXPORT_SYMBOL_GPL(bus_get_device_klist
);
977 * Yes, this forcibly breaks the klist abstraction temporarily. It
978 * just wants to sort the klist, not change reference counts and
979 * take/drop locks rapidly in the process. It does all this while
980 * holding the lock for the list, so objects can't otherwise be
981 * added/removed while we're swizzling.
983 static void device_insertion_sort_klist(struct device
*a
, struct list_head
*list
,
984 int (*compare
)(const struct device
*a
,
985 const struct device
*b
))
987 struct klist_node
*n
;
988 struct device_private
*dev_prv
;
991 list_for_each_entry(n
, list
, n_node
) {
992 dev_prv
= to_device_private_bus(n
);
994 if (compare(a
, b
) <= 0) {
995 list_move_tail(&a
->p
->knode_bus
.n_node
,
996 &b
->p
->knode_bus
.n_node
);
1000 list_move_tail(&a
->p
->knode_bus
.n_node
, list
);
1003 void bus_sort_breadthfirst(struct bus_type
*bus
,
1004 int (*compare
)(const struct device
*a
,
1005 const struct device
*b
))
1007 LIST_HEAD(sorted_devices
);
1008 struct klist_node
*n
, *tmp
;
1009 struct device_private
*dev_prv
;
1011 struct klist
*device_klist
;
1013 device_klist
= bus_get_device_klist(bus
);
1015 spin_lock(&device_klist
->k_lock
);
1016 list_for_each_entry_safe(n
, tmp
, &device_klist
->k_list
, n_node
) {
1017 dev_prv
= to_device_private_bus(n
);
1018 dev
= dev_prv
->device
;
1019 device_insertion_sort_klist(dev
, &sorted_devices
, compare
);
1021 list_splice(&sorted_devices
, &device_klist
->k_list
);
1022 spin_unlock(&device_klist
->k_lock
);
1024 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst
);
1027 * subsys_dev_iter_init - initialize subsys device iterator
1028 * @iter: subsys iterator to initialize
1029 * @subsys: the subsys we wanna iterate over
1030 * @start: the device to start iterating from, if any
1031 * @type: device_type of the devices to iterate over, NULL for all
1033 * Initialize subsys iterator @iter such that it iterates over devices
1034 * of @subsys. If @start is set, the list iteration will start there,
1035 * otherwise if it is NULL, the iteration starts at the beginning of
1038 void subsys_dev_iter_init(struct subsys_dev_iter
*iter
, struct bus_type
*subsys
,
1039 struct device
*start
, const struct device_type
*type
)
1041 struct klist_node
*start_knode
= NULL
;
1044 start_knode
= &start
->p
->knode_bus
;
1045 klist_iter_init_node(&subsys
->p
->klist_devices
, &iter
->ki
, start_knode
);
1048 EXPORT_SYMBOL_GPL(subsys_dev_iter_init
);
1051 * subsys_dev_iter_next - iterate to the next device
1052 * @iter: subsys iterator to proceed
1054 * Proceed @iter to the next device and return it. Returns NULL if
1055 * iteration is complete.
1057 * The returned device is referenced and won't be released till
1058 * iterator is proceed to the next device or exited. The caller is
1059 * free to do whatever it wants to do with the device including
1060 * calling back into subsys code.
1062 struct device
*subsys_dev_iter_next(struct subsys_dev_iter
*iter
)
1064 struct klist_node
*knode
;
1068 knode
= klist_next(&iter
->ki
);
1071 dev
= to_device_private_bus(knode
)->device
;
1072 if (!iter
->type
|| iter
->type
== dev
->type
)
1076 EXPORT_SYMBOL_GPL(subsys_dev_iter_next
);
1079 * subsys_dev_iter_exit - finish iteration
1080 * @iter: subsys iterator to finish
1082 * Finish an iteration. Always call this function after iteration is
1083 * complete whether the iteration ran till the end or not.
1085 void subsys_dev_iter_exit(struct subsys_dev_iter
*iter
)
1087 klist_iter_exit(&iter
->ki
);
1089 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit
);
1091 int subsys_interface_register(struct subsys_interface
*sif
)
1093 struct bus_type
*subsys
;
1094 struct subsys_dev_iter iter
;
1097 if (!sif
|| !sif
->subsys
)
1100 subsys
= bus_get(sif
->subsys
);
1104 mutex_lock(&subsys
->p
->mutex
);
1105 list_add_tail(&sif
->node
, &subsys
->p
->interfaces
);
1107 subsys_dev_iter_init(&iter
, subsys
, NULL
, NULL
);
1108 while ((dev
= subsys_dev_iter_next(&iter
)))
1109 sif
->add_dev(dev
, sif
);
1110 subsys_dev_iter_exit(&iter
);
1112 mutex_unlock(&subsys
->p
->mutex
);
1116 EXPORT_SYMBOL_GPL(subsys_interface_register
);
1118 void subsys_interface_unregister(struct subsys_interface
*sif
)
1120 struct bus_type
*subsys
;
1121 struct subsys_dev_iter iter
;
1124 if (!sif
|| !sif
->subsys
)
1127 subsys
= sif
->subsys
;
1129 mutex_lock(&subsys
->p
->mutex
);
1130 list_del_init(&sif
->node
);
1131 if (sif
->remove_dev
) {
1132 subsys_dev_iter_init(&iter
, subsys
, NULL
, NULL
);
1133 while ((dev
= subsys_dev_iter_next(&iter
)))
1134 sif
->remove_dev(dev
, sif
);
1135 subsys_dev_iter_exit(&iter
);
1137 mutex_unlock(&subsys
->p
->mutex
);
1141 EXPORT_SYMBOL_GPL(subsys_interface_unregister
);
1143 static void system_root_device_release(struct device
*dev
)
1148 static int subsys_register(struct bus_type
*subsys
,
1149 const struct attribute_group
**groups
,
1150 struct kobject
*parent_of_root
)
1155 err
= bus_register(subsys
);
1159 dev
= kzalloc(sizeof(struct device
), GFP_KERNEL
);
1165 err
= dev_set_name(dev
, "%s", subsys
->name
);
1169 dev
->kobj
.parent
= parent_of_root
;
1170 dev
->groups
= groups
;
1171 dev
->release
= system_root_device_release
;
1173 err
= device_register(dev
);
1177 subsys
->dev_root
= dev
;
1186 bus_unregister(subsys
);
1191 * subsys_system_register - register a subsystem at /sys/devices/system/
1192 * @subsys: system subsystem
1193 * @groups: default attributes for the root device
1195 * All 'system' subsystems have a /sys/devices/system/<name> root device
1196 * with the name of the subsystem. The root device can carry subsystem-
1197 * wide attributes. All registered devices are below this single root
1198 * device and are named after the subsystem with a simple enumeration
1199 * number appended. The registered devices are not explicitly named;
1200 * only 'id' in the device needs to be set.
1202 * Do not use this interface for anything new, it exists for compatibility
1203 * with bad ideas only. New subsystems should use plain subsystems; and
1204 * add the subsystem-wide attributes should be added to the subsystem
1205 * directory itself and not some create fake root-device placed in
1206 * /sys/devices/system/<name>.
1208 int subsys_system_register(struct bus_type
*subsys
,
1209 const struct attribute_group
**groups
)
1211 return subsys_register(subsys
, groups
, &system_kset
->kobj
);
1213 EXPORT_SYMBOL_GPL(subsys_system_register
);
1216 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1217 * @subsys: virtual subsystem
1218 * @groups: default attributes for the root device
1220 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1221 * with the name of the subystem. The root device can carry subsystem-wide
1222 * attributes. All registered devices are below this single root device.
1223 * There's no restriction on device naming. This is for kernel software
1224 * constructs which need sysfs interface.
1226 int subsys_virtual_register(struct bus_type
*subsys
,
1227 const struct attribute_group
**groups
)
1229 struct kobject
*virtual_dir
;
1231 virtual_dir
= virtual_device_parent(NULL
);
1235 return subsys_register(subsys
, groups
, virtual_dir
);
1237 EXPORT_SYMBOL_GPL(subsys_virtual_register
);
1239 int __init
buses_init(void)
1241 bus_kset
= kset_create_and_add("bus", &bus_uevent_ops
, NULL
);
1245 system_kset
= kset_create_and_add("system", NULL
, &devices_kset
->kobj
);