1 // SPDX-License-Identifier: GPL-2.0
3 * bus.c - bus driver management
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
8 * Copyright (c) 2007 Novell Inc.
11 #include <linux/async.h>
12 #include <linux/device/bus.h>
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>
20 #include <linux/sysfs.h>
22 #include "power/power.h"
24 /* /sys/devices/system */
25 static struct kset
*system_kset
;
27 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
30 * sysfs bindings for drivers
33 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
35 #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
36 struct driver_attribute driver_attr_##_name = \
37 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
39 static int __must_check
bus_rescan_devices_helper(struct device
*dev
,
42 static struct bus_type
*bus_get(struct bus_type
*bus
)
45 kset_get(&bus
->p
->subsys
);
51 static void bus_put(struct bus_type
*bus
)
54 kset_put(&bus
->p
->subsys
);
57 static ssize_t
drv_attr_show(struct kobject
*kobj
, struct attribute
*attr
,
60 struct driver_attribute
*drv_attr
= to_drv_attr(attr
);
61 struct driver_private
*drv_priv
= to_driver(kobj
);
65 ret
= drv_attr
->show(drv_priv
->driver
, buf
);
69 static ssize_t
drv_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
70 const char *buf
, size_t count
)
72 struct driver_attribute
*drv_attr
= to_drv_attr(attr
);
73 struct driver_private
*drv_priv
= to_driver(kobj
);
77 ret
= drv_attr
->store(drv_priv
->driver
, buf
, count
);
81 static const struct sysfs_ops driver_sysfs_ops
= {
82 .show
= drv_attr_show
,
83 .store
= drv_attr_store
,
86 static void driver_release(struct kobject
*kobj
)
88 struct driver_private
*drv_priv
= to_driver(kobj
);
90 pr_debug("driver: '%s': %s\n", kobject_name(kobj
), __func__
);
94 static struct kobj_type driver_ktype
= {
95 .sysfs_ops
= &driver_sysfs_ops
,
96 .release
= driver_release
,
100 * sysfs bindings for buses
102 static ssize_t
bus_attr_show(struct kobject
*kobj
, struct attribute
*attr
,
105 struct bus_attribute
*bus_attr
= to_bus_attr(attr
);
106 struct subsys_private
*subsys_priv
= to_subsys_private(kobj
);
110 ret
= bus_attr
->show(subsys_priv
->bus
, buf
);
114 static ssize_t
bus_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
115 const char *buf
, size_t count
)
117 struct bus_attribute
*bus_attr
= to_bus_attr(attr
);
118 struct subsys_private
*subsys_priv
= to_subsys_private(kobj
);
122 ret
= bus_attr
->store(subsys_priv
->bus
, buf
, count
);
126 static const struct sysfs_ops bus_sysfs_ops
= {
127 .show
= bus_attr_show
,
128 .store
= bus_attr_store
,
131 int bus_create_file(struct bus_type
*bus
, struct bus_attribute
*attr
)
135 error
= sysfs_create_file(&bus
->p
->subsys
.kobj
, &attr
->attr
);
141 EXPORT_SYMBOL_GPL(bus_create_file
);
143 void bus_remove_file(struct bus_type
*bus
, struct bus_attribute
*attr
)
146 sysfs_remove_file(&bus
->p
->subsys
.kobj
, &attr
->attr
);
150 EXPORT_SYMBOL_GPL(bus_remove_file
);
152 static void bus_release(struct kobject
*kobj
)
154 struct subsys_private
*priv
= to_subsys_private(kobj
);
155 struct bus_type
*bus
= priv
->bus
;
161 static struct kobj_type bus_ktype
= {
162 .sysfs_ops
= &bus_sysfs_ops
,
163 .release
= bus_release
,
166 static int bus_uevent_filter(struct kset
*kset
, struct kobject
*kobj
)
168 struct kobj_type
*ktype
= get_ktype(kobj
);
170 if (ktype
== &bus_ktype
)
175 static const struct kset_uevent_ops bus_uevent_ops
= {
176 .filter
= bus_uevent_filter
,
179 static struct kset
*bus_kset
;
181 /* Manually detach a device from its associated driver. */
182 static ssize_t
unbind_store(struct device_driver
*drv
, const char *buf
,
185 struct bus_type
*bus
= bus_get(drv
->bus
);
189 dev
= bus_find_device_by_name(bus
, NULL
, buf
);
190 if (dev
&& dev
->driver
== drv
) {
191 device_driver_detach(dev
);
198 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind
, 0200, NULL
, unbind_store
);
201 * Manually attach a device to a driver.
202 * Note: the driver must want to bind to the device,
203 * it is not possible to override the driver's id table.
205 static ssize_t
bind_store(struct device_driver
*drv
, const char *buf
,
208 struct bus_type
*bus
= bus_get(drv
->bus
);
212 dev
= bus_find_device_by_name(bus
, NULL
, buf
);
213 if (dev
&& driver_match_device(drv
, dev
)) {
214 err
= device_driver_attach(drv
, dev
);
224 static DRIVER_ATTR_IGNORE_LOCKDEP(bind
, 0200, NULL
, bind_store
);
226 static ssize_t
drivers_autoprobe_show(struct bus_type
*bus
, char *buf
)
228 return sysfs_emit(buf
, "%d\n", bus
->p
->drivers_autoprobe
);
231 static ssize_t
drivers_autoprobe_store(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
drivers_probe_store(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 (!error
&& (dev
= next_device(&i
)))
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
, const void *data
,
324 int (*match
)(struct device
*dev
, const 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
);
343 * subsys_find_device_by_id - find a device with a specific enumeration number
345 * @id: index 'id' in struct device
346 * @hint: device to check first
348 * Check the hint's next object and if it is a match return it directly,
349 * otherwise, fall back to a full list search. Either way a reference for
350 * the returned object is taken.
352 struct device
*subsys_find_device_by_id(struct bus_type
*subsys
, unsigned int id
,
362 klist_iter_init_node(&subsys
->p
->klist_devices
, &i
, &hint
->p
->knode_bus
);
363 dev
= next_device(&i
);
364 if (dev
&& dev
->id
== id
&& get_device(dev
)) {
371 klist_iter_init_node(&subsys
->p
->klist_devices
, &i
, NULL
);
372 while ((dev
= next_device(&i
))) {
373 if (dev
->id
== id
&& get_device(dev
)) {
381 EXPORT_SYMBOL_GPL(subsys_find_device_by_id
);
383 static struct device_driver
*next_driver(struct klist_iter
*i
)
385 struct klist_node
*n
= klist_next(i
);
386 struct driver_private
*drv_priv
;
389 drv_priv
= container_of(n
, struct driver_private
, knode_bus
);
390 return drv_priv
->driver
;
396 * bus_for_each_drv - driver iterator
397 * @bus: bus we're dealing with.
398 * @start: driver to start iterating on.
399 * @data: data to pass to the callback.
400 * @fn: function to call for each driver.
402 * This is nearly identical to the device iterator above.
403 * We iterate over each driver that belongs to @bus, and call
404 * @fn for each. If @fn returns anything but 0, we break out
405 * and return it. If @start is not NULL, we use it as the head
408 * NOTE: we don't return the driver that returns a non-zero
409 * value, nor do we leave the reference count incremented for that
410 * driver. If the caller needs to know that info, it must set it
411 * in the callback. It must also be sure to increment the refcount
412 * so it doesn't disappear before returning to the caller.
414 int bus_for_each_drv(struct bus_type
*bus
, struct device_driver
*start
,
415 void *data
, int (*fn
)(struct device_driver
*, void *))
418 struct device_driver
*drv
;
424 klist_iter_init_node(&bus
->p
->klist_drivers
, &i
,
425 start
? &start
->p
->knode_bus
: NULL
);
426 while ((drv
= next_driver(&i
)) && !error
)
427 error
= fn(drv
, data
);
431 EXPORT_SYMBOL_GPL(bus_for_each_drv
);
434 * bus_add_device - add device to bus
435 * @dev: device being added
437 * - Add device's bus attributes.
438 * - Create links to device's bus.
439 * - Add the device to its bus's list of devices.
441 int bus_add_device(struct device
*dev
)
443 struct bus_type
*bus
= bus_get(dev
->bus
);
447 pr_debug("bus: '%s': add device %s\n", bus
->name
, dev_name(dev
));
448 error
= device_add_groups(dev
, bus
->dev_groups
);
451 error
= sysfs_create_link(&bus
->p
->devices_kset
->kobj
,
452 &dev
->kobj
, dev_name(dev
));
455 error
= sysfs_create_link(&dev
->kobj
,
456 &dev
->bus
->p
->subsys
.kobj
, "subsystem");
459 klist_add_tail(&dev
->p
->knode_bus
, &bus
->p
->klist_devices
);
464 sysfs_remove_link(&bus
->p
->devices_kset
->kobj
, dev_name(dev
));
466 device_remove_groups(dev
, bus
->dev_groups
);
473 * bus_probe_device - probe drivers for a new device
474 * @dev: device to probe
476 * - Automatically probe for a driver if the bus allows it.
478 void bus_probe_device(struct device
*dev
)
480 struct bus_type
*bus
= dev
->bus
;
481 struct subsys_interface
*sif
;
486 if (bus
->p
->drivers_autoprobe
)
487 device_initial_probe(dev
);
489 mutex_lock(&bus
->p
->mutex
);
490 list_for_each_entry(sif
, &bus
->p
->interfaces
, node
)
492 sif
->add_dev(dev
, sif
);
493 mutex_unlock(&bus
->p
->mutex
);
497 * bus_remove_device - remove device from bus
498 * @dev: device to be removed
500 * - Remove device from all interfaces.
501 * - Remove symlink from bus' directory.
502 * - Delete device from bus's list.
503 * - Detach from its driver.
504 * - Drop reference taken in bus_add_device().
506 void bus_remove_device(struct device
*dev
)
508 struct bus_type
*bus
= dev
->bus
;
509 struct subsys_interface
*sif
;
514 mutex_lock(&bus
->p
->mutex
);
515 list_for_each_entry(sif
, &bus
->p
->interfaces
, node
)
517 sif
->remove_dev(dev
, sif
);
518 mutex_unlock(&bus
->p
->mutex
);
520 sysfs_remove_link(&dev
->kobj
, "subsystem");
521 sysfs_remove_link(&dev
->bus
->p
->devices_kset
->kobj
,
523 device_remove_groups(dev
, dev
->bus
->dev_groups
);
524 if (klist_node_attached(&dev
->p
->knode_bus
))
525 klist_del(&dev
->p
->knode_bus
);
527 pr_debug("bus: '%s': remove device %s\n",
528 dev
->bus
->name
, dev_name(dev
));
529 device_release_driver(dev
);
533 static int __must_check
add_bind_files(struct device_driver
*drv
)
537 ret
= driver_create_file(drv
, &driver_attr_unbind
);
539 ret
= driver_create_file(drv
, &driver_attr_bind
);
541 driver_remove_file(drv
, &driver_attr_unbind
);
546 static void remove_bind_files(struct device_driver
*drv
)
548 driver_remove_file(drv
, &driver_attr_bind
);
549 driver_remove_file(drv
, &driver_attr_unbind
);
552 static BUS_ATTR_WO(drivers_probe
);
553 static BUS_ATTR_RW(drivers_autoprobe
);
555 static int add_probe_files(struct bus_type
*bus
)
559 retval
= bus_create_file(bus
, &bus_attr_drivers_probe
);
563 retval
= bus_create_file(bus
, &bus_attr_drivers_autoprobe
);
565 bus_remove_file(bus
, &bus_attr_drivers_probe
);
570 static void remove_probe_files(struct bus_type
*bus
)
572 bus_remove_file(bus
, &bus_attr_drivers_autoprobe
);
573 bus_remove_file(bus
, &bus_attr_drivers_probe
);
576 static ssize_t
uevent_store(struct device_driver
*drv
, const char *buf
,
581 rc
= kobject_synth_uevent(&drv
->p
->kobj
, buf
, count
);
582 return rc
? rc
: count
;
584 static DRIVER_ATTR_WO(uevent
);
587 * bus_add_driver - Add a driver to the bus.
590 int bus_add_driver(struct device_driver
*drv
)
592 struct bus_type
*bus
;
593 struct driver_private
*priv
;
596 bus
= bus_get(drv
->bus
);
600 pr_debug("bus: '%s': add driver %s\n", bus
->name
, drv
->name
);
602 priv
= kzalloc(sizeof(*priv
), GFP_KERNEL
);
607 klist_init(&priv
->klist_devices
, NULL
, NULL
);
610 priv
->kobj
.kset
= bus
->p
->drivers_kset
;
611 error
= kobject_init_and_add(&priv
->kobj
, &driver_ktype
, NULL
,
616 klist_add_tail(&priv
->knode_bus
, &bus
->p
->klist_drivers
);
617 if (drv
->bus
->p
->drivers_autoprobe
) {
618 error
= driver_attach(drv
);
622 module_add_driver(drv
->owner
, drv
);
624 error
= driver_create_file(drv
, &driver_attr_uevent
);
626 printk(KERN_ERR
"%s: uevent attr (%s) failed\n",
627 __func__
, drv
->name
);
629 error
= driver_add_groups(drv
, bus
->drv_groups
);
631 /* How the hell do we get out of this pickle? Give up */
632 printk(KERN_ERR
"%s: driver_add_groups(%s) failed\n",
633 __func__
, drv
->name
);
636 if (!drv
->suppress_bind_attrs
) {
637 error
= add_bind_files(drv
);
640 printk(KERN_ERR
"%s: add_bind_files(%s) failed\n",
641 __func__
, drv
->name
);
648 kobject_put(&priv
->kobj
);
649 /* drv->p is freed in driver_release() */
657 * bus_remove_driver - delete driver from bus's knowledge.
660 * Detach the driver from the devices it controls, and remove
661 * it from its bus's list of drivers. Finally, we drop the reference
662 * to the bus we took in bus_add_driver().
664 void bus_remove_driver(struct device_driver
*drv
)
669 if (!drv
->suppress_bind_attrs
)
670 remove_bind_files(drv
);
671 driver_remove_groups(drv
, drv
->bus
->drv_groups
);
672 driver_remove_file(drv
, &driver_attr_uevent
);
673 klist_remove(&drv
->p
->knode_bus
);
674 pr_debug("bus: '%s': remove driver %s\n", drv
->bus
->name
, drv
->name
);
676 module_remove_driver(drv
);
677 kobject_put(&drv
->p
->kobj
);
681 /* Helper for bus_rescan_devices's iter */
682 static int __must_check
bus_rescan_devices_helper(struct device
*dev
,
688 if (dev
->parent
&& dev
->bus
->need_parent_lock
)
689 device_lock(dev
->parent
);
690 ret
= device_attach(dev
);
691 if (dev
->parent
&& dev
->bus
->need_parent_lock
)
692 device_unlock(dev
->parent
);
694 return ret
< 0 ? ret
: 0;
698 * bus_rescan_devices - rescan devices on the bus for possible drivers
699 * @bus: the bus to scan.
701 * This function will look for devices on the bus with no driver
702 * attached and rescan it against existing drivers to see if it matches
703 * any by calling device_attach() for the unbound devices.
705 int bus_rescan_devices(struct bus_type
*bus
)
707 return bus_for_each_dev(bus
, NULL
, NULL
, bus_rescan_devices_helper
);
709 EXPORT_SYMBOL_GPL(bus_rescan_devices
);
712 * device_reprobe - remove driver for a device and probe for a new driver
713 * @dev: the device to reprobe
715 * This function detaches the attached driver (if any) for the given
716 * device and restarts the driver probing process. It is intended
717 * to use if probing criteria changed during a devices lifetime and
718 * driver attachment should change accordingly.
720 int device_reprobe(struct device
*dev
)
723 device_driver_detach(dev
);
724 return bus_rescan_devices_helper(dev
, NULL
);
726 EXPORT_SYMBOL_GPL(device_reprobe
);
728 static int bus_add_groups(struct bus_type
*bus
,
729 const struct attribute_group
**groups
)
731 return sysfs_create_groups(&bus
->p
->subsys
.kobj
, groups
);
734 static void bus_remove_groups(struct bus_type
*bus
,
735 const struct attribute_group
**groups
)
737 sysfs_remove_groups(&bus
->p
->subsys
.kobj
, groups
);
740 static void klist_devices_get(struct klist_node
*n
)
742 struct device_private
*dev_prv
= to_device_private_bus(n
);
743 struct device
*dev
= dev_prv
->device
;
748 static void klist_devices_put(struct klist_node
*n
)
750 struct device_private
*dev_prv
= to_device_private_bus(n
);
751 struct device
*dev
= dev_prv
->device
;
756 static ssize_t
bus_uevent_store(struct bus_type
*bus
,
757 const char *buf
, size_t count
)
761 rc
= kobject_synth_uevent(&bus
->p
->subsys
.kobj
, buf
, count
);
762 return rc
? rc
: count
;
765 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
766 * here, but can not use it as earlier in the file we have
767 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
770 static struct bus_attribute bus_attr_uevent
= __ATTR(uevent
, 0200, NULL
,
774 * bus_register - register a driver-core subsystem
775 * @bus: bus to register
777 * Once we have that, we register the bus with the kobject
778 * infrastructure, then register the children subsystems it has:
779 * the devices and drivers that belong to the subsystem.
781 int bus_register(struct bus_type
*bus
)
784 struct subsys_private
*priv
;
785 struct lock_class_key
*key
= &bus
->lock_key
;
787 priv
= kzalloc(sizeof(struct subsys_private
), GFP_KERNEL
);
794 BLOCKING_INIT_NOTIFIER_HEAD(&priv
->bus_notifier
);
796 retval
= kobject_set_name(&priv
->subsys
.kobj
, "%s", bus
->name
);
800 priv
->subsys
.kobj
.kset
= bus_kset
;
801 priv
->subsys
.kobj
.ktype
= &bus_ktype
;
802 priv
->drivers_autoprobe
= 1;
804 retval
= kset_register(&priv
->subsys
);
808 retval
= bus_create_file(bus
, &bus_attr_uevent
);
810 goto bus_uevent_fail
;
812 priv
->devices_kset
= kset_create_and_add("devices", NULL
,
814 if (!priv
->devices_kset
) {
816 goto bus_devices_fail
;
819 priv
->drivers_kset
= kset_create_and_add("drivers", NULL
,
821 if (!priv
->drivers_kset
) {
823 goto bus_drivers_fail
;
826 INIT_LIST_HEAD(&priv
->interfaces
);
827 __mutex_init(&priv
->mutex
, "subsys mutex", key
);
828 klist_init(&priv
->klist_devices
, klist_devices_get
, klist_devices_put
);
829 klist_init(&priv
->klist_drivers
, NULL
, NULL
);
831 retval
= add_probe_files(bus
);
833 goto bus_probe_files_fail
;
835 retval
= bus_add_groups(bus
, bus
->bus_groups
);
837 goto bus_groups_fail
;
839 pr_debug("bus: '%s': registered\n", bus
->name
);
843 remove_probe_files(bus
);
844 bus_probe_files_fail
:
845 kset_unregister(bus
->p
->drivers_kset
);
847 kset_unregister(bus
->p
->devices_kset
);
849 bus_remove_file(bus
, &bus_attr_uevent
);
851 kset_unregister(&bus
->p
->subsys
);
857 EXPORT_SYMBOL_GPL(bus_register
);
860 * bus_unregister - remove a bus from the system
863 * Unregister the child subsystems and the bus itself.
864 * Finally, we call bus_put() to release the refcount
866 void bus_unregister(struct bus_type
*bus
)
868 pr_debug("bus: '%s': unregistering\n", bus
->name
);
870 device_unregister(bus
->dev_root
);
871 bus_remove_groups(bus
, bus
->bus_groups
);
872 remove_probe_files(bus
);
873 kset_unregister(bus
->p
->drivers_kset
);
874 kset_unregister(bus
->p
->devices_kset
);
875 bus_remove_file(bus
, &bus_attr_uevent
);
876 kset_unregister(&bus
->p
->subsys
);
878 EXPORT_SYMBOL_GPL(bus_unregister
);
880 int bus_register_notifier(struct bus_type
*bus
, struct notifier_block
*nb
)
882 return blocking_notifier_chain_register(&bus
->p
->bus_notifier
, nb
);
884 EXPORT_SYMBOL_GPL(bus_register_notifier
);
886 int bus_unregister_notifier(struct bus_type
*bus
, struct notifier_block
*nb
)
888 return blocking_notifier_chain_unregister(&bus
->p
->bus_notifier
, nb
);
890 EXPORT_SYMBOL_GPL(bus_unregister_notifier
);
892 struct kset
*bus_get_kset(struct bus_type
*bus
)
894 return &bus
->p
->subsys
;
896 EXPORT_SYMBOL_GPL(bus_get_kset
);
898 struct klist
*bus_get_device_klist(struct bus_type
*bus
)
900 return &bus
->p
->klist_devices
;
902 EXPORT_SYMBOL_GPL(bus_get_device_klist
);
905 * Yes, this forcibly breaks the klist abstraction temporarily. It
906 * just wants to sort the klist, not change reference counts and
907 * take/drop locks rapidly in the process. It does all this while
908 * holding the lock for the list, so objects can't otherwise be
909 * added/removed while we're swizzling.
911 static void device_insertion_sort_klist(struct device
*a
, struct list_head
*list
,
912 int (*compare
)(const struct device
*a
,
913 const struct device
*b
))
915 struct klist_node
*n
;
916 struct device_private
*dev_prv
;
919 list_for_each_entry(n
, list
, n_node
) {
920 dev_prv
= to_device_private_bus(n
);
922 if (compare(a
, b
) <= 0) {
923 list_move_tail(&a
->p
->knode_bus
.n_node
,
924 &b
->p
->knode_bus
.n_node
);
928 list_move_tail(&a
->p
->knode_bus
.n_node
, list
);
931 void bus_sort_breadthfirst(struct bus_type
*bus
,
932 int (*compare
)(const struct device
*a
,
933 const struct device
*b
))
935 LIST_HEAD(sorted_devices
);
936 struct klist_node
*n
, *tmp
;
937 struct device_private
*dev_prv
;
939 struct klist
*device_klist
;
941 device_klist
= bus_get_device_klist(bus
);
943 spin_lock(&device_klist
->k_lock
);
944 list_for_each_entry_safe(n
, tmp
, &device_klist
->k_list
, n_node
) {
945 dev_prv
= to_device_private_bus(n
);
946 dev
= dev_prv
->device
;
947 device_insertion_sort_klist(dev
, &sorted_devices
, compare
);
949 list_splice(&sorted_devices
, &device_klist
->k_list
);
950 spin_unlock(&device_klist
->k_lock
);
952 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst
);
955 * subsys_dev_iter_init - initialize subsys device iterator
956 * @iter: subsys iterator to initialize
957 * @subsys: the subsys we wanna iterate over
958 * @start: the device to start iterating from, if any
959 * @type: device_type of the devices to iterate over, NULL for all
961 * Initialize subsys iterator @iter such that it iterates over devices
962 * of @subsys. If @start is set, the list iteration will start there,
963 * otherwise if it is NULL, the iteration starts at the beginning of
966 void subsys_dev_iter_init(struct subsys_dev_iter
*iter
, struct bus_type
*subsys
,
967 struct device
*start
, const struct device_type
*type
)
969 struct klist_node
*start_knode
= NULL
;
972 start_knode
= &start
->p
->knode_bus
;
973 klist_iter_init_node(&subsys
->p
->klist_devices
, &iter
->ki
, start_knode
);
976 EXPORT_SYMBOL_GPL(subsys_dev_iter_init
);
979 * subsys_dev_iter_next - iterate to the next device
980 * @iter: subsys iterator to proceed
982 * Proceed @iter to the next device and return it. Returns NULL if
983 * iteration is complete.
985 * The returned device is referenced and won't be released till
986 * iterator is proceed to the next device or exited. The caller is
987 * free to do whatever it wants to do with the device including
988 * calling back into subsys code.
990 struct device
*subsys_dev_iter_next(struct subsys_dev_iter
*iter
)
992 struct klist_node
*knode
;
996 knode
= klist_next(&iter
->ki
);
999 dev
= to_device_private_bus(knode
)->device
;
1000 if (!iter
->type
|| iter
->type
== dev
->type
)
1004 EXPORT_SYMBOL_GPL(subsys_dev_iter_next
);
1007 * subsys_dev_iter_exit - finish iteration
1008 * @iter: subsys iterator to finish
1010 * Finish an iteration. Always call this function after iteration is
1011 * complete whether the iteration ran till the end or not.
1013 void subsys_dev_iter_exit(struct subsys_dev_iter
*iter
)
1015 klist_iter_exit(&iter
->ki
);
1017 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit
);
1019 int subsys_interface_register(struct subsys_interface
*sif
)
1021 struct bus_type
*subsys
;
1022 struct subsys_dev_iter iter
;
1025 if (!sif
|| !sif
->subsys
)
1028 subsys
= bus_get(sif
->subsys
);
1032 mutex_lock(&subsys
->p
->mutex
);
1033 list_add_tail(&sif
->node
, &subsys
->p
->interfaces
);
1035 subsys_dev_iter_init(&iter
, subsys
, NULL
, NULL
);
1036 while ((dev
= subsys_dev_iter_next(&iter
)))
1037 sif
->add_dev(dev
, sif
);
1038 subsys_dev_iter_exit(&iter
);
1040 mutex_unlock(&subsys
->p
->mutex
);
1044 EXPORT_SYMBOL_GPL(subsys_interface_register
);
1046 void subsys_interface_unregister(struct subsys_interface
*sif
)
1048 struct bus_type
*subsys
;
1049 struct subsys_dev_iter iter
;
1052 if (!sif
|| !sif
->subsys
)
1055 subsys
= sif
->subsys
;
1057 mutex_lock(&subsys
->p
->mutex
);
1058 list_del_init(&sif
->node
);
1059 if (sif
->remove_dev
) {
1060 subsys_dev_iter_init(&iter
, subsys
, NULL
, NULL
);
1061 while ((dev
= subsys_dev_iter_next(&iter
)))
1062 sif
->remove_dev(dev
, sif
);
1063 subsys_dev_iter_exit(&iter
);
1065 mutex_unlock(&subsys
->p
->mutex
);
1069 EXPORT_SYMBOL_GPL(subsys_interface_unregister
);
1071 static void system_root_device_release(struct device
*dev
)
1076 static int subsys_register(struct bus_type
*subsys
,
1077 const struct attribute_group
**groups
,
1078 struct kobject
*parent_of_root
)
1083 err
= bus_register(subsys
);
1087 dev
= kzalloc(sizeof(struct device
), GFP_KERNEL
);
1093 err
= dev_set_name(dev
, "%s", subsys
->name
);
1097 dev
->kobj
.parent
= parent_of_root
;
1098 dev
->groups
= groups
;
1099 dev
->release
= system_root_device_release
;
1101 err
= device_register(dev
);
1105 subsys
->dev_root
= dev
;
1114 bus_unregister(subsys
);
1119 * subsys_system_register - register a subsystem at /sys/devices/system/
1120 * @subsys: system subsystem
1121 * @groups: default attributes for the root device
1123 * All 'system' subsystems have a /sys/devices/system/<name> root device
1124 * with the name of the subsystem. The root device can carry subsystem-
1125 * wide attributes. All registered devices are below this single root
1126 * device and are named after the subsystem with a simple enumeration
1127 * number appended. The registered devices are not explicitly named;
1128 * only 'id' in the device needs to be set.
1130 * Do not use this interface for anything new, it exists for compatibility
1131 * with bad ideas only. New subsystems should use plain subsystems; and
1132 * add the subsystem-wide attributes should be added to the subsystem
1133 * directory itself and not some create fake root-device placed in
1134 * /sys/devices/system/<name>.
1136 int subsys_system_register(struct bus_type
*subsys
,
1137 const struct attribute_group
**groups
)
1139 return subsys_register(subsys
, groups
, &system_kset
->kobj
);
1141 EXPORT_SYMBOL_GPL(subsys_system_register
);
1144 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1145 * @subsys: virtual subsystem
1146 * @groups: default attributes for the root device
1148 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1149 * with the name of the subystem. The root device can carry subsystem-wide
1150 * attributes. All registered devices are below this single root device.
1151 * There's no restriction on device naming. This is for kernel software
1152 * constructs which need sysfs interface.
1154 int subsys_virtual_register(struct bus_type
*subsys
,
1155 const struct attribute_group
**groups
)
1157 struct kobject
*virtual_dir
;
1159 virtual_dir
= virtual_device_parent(NULL
);
1163 return subsys_register(subsys
, groups
, virtual_dir
);
1165 EXPORT_SYMBOL_GPL(subsys_virtual_register
);
1167 int __init
buses_init(void)
1169 bus_kset
= kset_create_and_add("bus", &bus_uevent_ops
, NULL
);
1173 system_kset
= kset_create_and_add("system", NULL
, &devices_kset
->kobj
);