2 * bus.c - bus driver management
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
7 * This file is released under the GPLv2
11 #include <linux/device.h>
12 #include <linux/module.h>
13 #include <linux/errno.h>
14 #include <linux/init.h>
15 #include <linux/string.h>
17 #include "power/power.h"
19 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
20 #define to_bus(obj) container_of(obj, struct bus_type, subsys.kset.kobj)
23 * sysfs bindings for drivers
26 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
27 #define to_driver(obj) container_of(obj, struct device_driver, kobj)
31 drv_attr_show(struct kobject
* kobj
, struct attribute
* attr
, char * buf
)
33 struct driver_attribute
* drv_attr
= to_drv_attr(attr
);
34 struct device_driver
* drv
= to_driver(kobj
);
38 ret
= drv_attr
->show(drv
, buf
);
43 drv_attr_store(struct kobject
* kobj
, struct attribute
* attr
,
44 const char * buf
, size_t count
)
46 struct driver_attribute
* drv_attr
= to_drv_attr(attr
);
47 struct device_driver
* drv
= to_driver(kobj
);
51 ret
= drv_attr
->store(drv
, buf
, count
);
55 static struct sysfs_ops driver_sysfs_ops
= {
56 .show
= drv_attr_show
,
57 .store
= drv_attr_store
,
61 static void driver_release(struct kobject
* kobj
)
63 struct device_driver
* drv
= to_driver(kobj
);
64 complete(&drv
->unloaded
);
67 static struct kobj_type ktype_driver
= {
68 .sysfs_ops
= &driver_sysfs_ops
,
69 .release
= driver_release
,
74 * sysfs bindings for buses
79 bus_attr_show(struct kobject
* kobj
, struct attribute
* attr
, char * buf
)
81 struct bus_attribute
* bus_attr
= to_bus_attr(attr
);
82 struct bus_type
* bus
= to_bus(kobj
);
86 ret
= bus_attr
->show(bus
, buf
);
91 bus_attr_store(struct kobject
* kobj
, struct attribute
* attr
,
92 const char * buf
, size_t count
)
94 struct bus_attribute
* bus_attr
= to_bus_attr(attr
);
95 struct bus_type
* bus
= to_bus(kobj
);
99 ret
= bus_attr
->store(bus
, buf
, count
);
103 static struct sysfs_ops bus_sysfs_ops
= {
104 .show
= bus_attr_show
,
105 .store
= bus_attr_store
,
108 int bus_create_file(struct bus_type
* bus
, struct bus_attribute
* attr
)
112 error
= sysfs_create_file(&bus
->subsys
.kset
.kobj
, &attr
->attr
);
119 void bus_remove_file(struct bus_type
* bus
, struct bus_attribute
* attr
)
122 sysfs_remove_file(&bus
->subsys
.kset
.kobj
, &attr
->attr
);
127 static struct kobj_type ktype_bus
= {
128 .sysfs_ops
= &bus_sysfs_ops
,
132 static decl_subsys(bus
, &ktype_bus
, NULL
);
135 #ifdef CONFIG_HOTPLUG
137 /* Manually detach a device from its associated driver. */
138 static int driver_helper(struct device
*dev
, void *data
)
140 const char *name
= data
;
142 if (strcmp(name
, dev
->bus_id
) == 0)
147 static ssize_t
driver_unbind(struct device_driver
*drv
,
148 const char *buf
, size_t count
)
150 struct bus_type
*bus
= get_bus(drv
->bus
);
154 dev
= bus_find_device(bus
, NULL
, (void *)buf
, driver_helper
);
155 if (dev
&& dev
->driver
== drv
) {
156 if (dev
->parent
) /* Needed for USB */
157 down(&dev
->parent
->sem
);
158 device_release_driver(dev
);
160 up(&dev
->parent
->sem
);
167 static DRIVER_ATTR(unbind
, S_IWUSR
, NULL
, driver_unbind
);
170 * Manually attach a device to a driver.
171 * Note: the driver must want to bind to the device,
172 * it is not possible to override the driver's id table.
174 static ssize_t
driver_bind(struct device_driver
*drv
,
175 const char *buf
, size_t count
)
177 struct bus_type
*bus
= get_bus(drv
->bus
);
181 dev
= bus_find_device(bus
, NULL
, (void *)buf
, driver_helper
);
182 if (dev
&& dev
->driver
== NULL
) {
183 if (dev
->parent
) /* Needed for USB */
184 down(&dev
->parent
->sem
);
186 err
= driver_probe_device(drv
, dev
);
189 up(&dev
->parent
->sem
);
191 if (err
> 0) /* success */
193 else if (err
== 0) /* driver didn't accept device */
200 static DRIVER_ATTR(bind
, S_IWUSR
, NULL
, driver_bind
);
204 static struct device
* next_device(struct klist_iter
* i
)
206 struct klist_node
* n
= klist_next(i
);
207 return n
? container_of(n
, struct device
, knode_bus
) : NULL
;
211 * bus_for_each_dev - device iterator.
213 * @start: device to start iterating from.
214 * @data: data for the callback.
215 * @fn: function to be called for each device.
217 * Iterate over @bus's list of devices, and call @fn for each,
218 * passing it @data. If @start is not NULL, we use that device to
219 * begin iterating from.
221 * We check the return of @fn each time. If it returns anything
222 * other than 0, we break out and return that value.
224 * NOTE: The device that returns a non-zero value is not retained
225 * in any way, nor is its refcount incremented. If the caller needs
226 * to retain this data, it should do, and increment the reference
227 * count in the supplied callback.
230 int bus_for_each_dev(struct bus_type
* bus
, struct device
* start
,
231 void * data
, int (*fn
)(struct device
*, void *))
240 klist_iter_init_node(&bus
->klist_devices
, &i
,
241 (start
? &start
->knode_bus
: NULL
));
242 while ((dev
= next_device(&i
)) && !error
)
243 error
= fn(dev
, data
);
249 * bus_find_device - device iterator for locating a particular device.
251 * @start: Device to begin with
252 * @data: Data to pass to match function
253 * @match: Callback function to check device
255 * This is similar to the bus_for_each_dev() function above, but it
256 * returns a reference to a device that is 'found' for later use, as
257 * determined by the @match callback.
259 * The callback should return 0 if the device doesn't match and non-zero
260 * if it does. If the callback returns non-zero, this function will
261 * return to the caller and not iterate over any more devices.
263 struct device
* bus_find_device(struct bus_type
*bus
,
264 struct device
*start
, void *data
,
265 int (*match
)(struct device
*, void *))
273 klist_iter_init_node(&bus
->klist_devices
, &i
,
274 (start
? &start
->knode_bus
: NULL
));
275 while ((dev
= next_device(&i
)))
276 if (match(dev
, data
) && get_device(dev
))
283 static struct device_driver
* next_driver(struct klist_iter
* i
)
285 struct klist_node
* n
= klist_next(i
);
286 return n
? container_of(n
, struct device_driver
, knode_bus
) : NULL
;
290 * bus_for_each_drv - driver iterator
291 * @bus: bus we're dealing with.
292 * @start: driver to start iterating on.
293 * @data: data to pass to the callback.
294 * @fn: function to call for each driver.
296 * This is nearly identical to the device iterator above.
297 * We iterate over each driver that belongs to @bus, and call
298 * @fn for each. If @fn returns anything but 0, we break out
299 * and return it. If @start is not NULL, we use it as the head
302 * NOTE: we don't return the driver that returns a non-zero
303 * value, nor do we leave the reference count incremented for that
304 * driver. If the caller needs to know that info, it must set it
305 * in the callback. It must also be sure to increment the refcount
306 * so it doesn't disappear before returning to the caller.
309 int bus_for_each_drv(struct bus_type
* bus
, struct device_driver
* start
,
310 void * data
, int (*fn
)(struct device_driver
*, void *))
313 struct device_driver
* drv
;
319 klist_iter_init_node(&bus
->klist_drivers
, &i
,
320 start
? &start
->knode_bus
: NULL
);
321 while ((drv
= next_driver(&i
)) && !error
)
322 error
= fn(drv
, data
);
327 static int device_add_attrs(struct bus_type
* bus
, struct device
* dev
)
332 if (bus
->dev_attrs
) {
333 for (i
= 0; attr_name(bus
->dev_attrs
[i
]); i
++) {
334 error
= device_create_file(dev
,&bus
->dev_attrs
[i
]);
343 device_remove_file(dev
,&bus
->dev_attrs
[i
]);
348 static void device_remove_attrs(struct bus_type
* bus
, struct device
* dev
)
352 if (bus
->dev_attrs
) {
353 for (i
= 0; attr_name(bus
->dev_attrs
[i
]); i
++)
354 device_remove_file(dev
,&bus
->dev_attrs
[i
]);
360 * bus_add_device - add device to bus
361 * @dev: device being added
363 * - Add the device to its bus's list of devices.
364 * - Create link to device's bus.
366 int bus_add_device(struct device
* dev
)
368 struct bus_type
* bus
= get_bus(dev
->bus
);
372 pr_debug("bus %s: add device %s\n", bus
->name
, dev
->bus_id
);
373 error
= device_add_attrs(bus
, dev
);
376 error
= sysfs_create_link(&bus
->devices
.kobj
,
377 &dev
->kobj
, dev
->bus_id
);
380 error
= sysfs_create_link(&dev
->kobj
,
381 &dev
->bus
->subsys
.kset
.kobj
, "subsystem");
384 error
= sysfs_create_link(&dev
->kobj
,
385 &dev
->bus
->subsys
.kset
.kobj
, "bus");
392 sysfs_remove_link(&dev
->kobj
, "subsystem");
394 sysfs_remove_link(&bus
->devices
.kobj
, dev
->bus_id
);
396 device_remove_attrs(bus
, dev
);
403 * bus_attach_device - add device to bus
404 * @dev: device tried to attach to a driver
406 * - Add device to bus's list of devices.
407 * - Try to attach to driver.
409 int bus_attach_device(struct device
* dev
)
411 struct bus_type
*bus
= dev
->bus
;
415 dev
->is_registered
= 1;
416 ret
= device_attach(dev
);
418 klist_add_tail(&dev
->knode_bus
, &bus
->klist_devices
);
421 dev
->is_registered
= 0;
427 * bus_remove_device - remove device from bus
428 * @dev: device to be removed
430 * - Remove symlink from bus's directory.
431 * - Delete device from bus's list.
432 * - Detach from its driver.
433 * - Drop reference taken in bus_add_device().
435 void bus_remove_device(struct device
* dev
)
438 sysfs_remove_link(&dev
->kobj
, "subsystem");
439 sysfs_remove_link(&dev
->kobj
, "bus");
440 sysfs_remove_link(&dev
->bus
->devices
.kobj
, dev
->bus_id
);
441 device_remove_attrs(dev
->bus
, dev
);
442 if (dev
->is_registered
) {
443 dev
->is_registered
= 0;
444 klist_del(&dev
->knode_bus
);
446 pr_debug("bus %s: remove device %s\n", dev
->bus
->name
, dev
->bus_id
);
447 device_release_driver(dev
);
452 static int driver_add_attrs(struct bus_type
* bus
, struct device_driver
* drv
)
457 if (bus
->drv_attrs
) {
458 for (i
= 0; attr_name(bus
->drv_attrs
[i
]); i
++) {
459 error
= driver_create_file(drv
, &bus
->drv_attrs
[i
]);
468 driver_remove_file(drv
, &bus
->drv_attrs
[i
]);
473 static void driver_remove_attrs(struct bus_type
* bus
, struct device_driver
* drv
)
477 if (bus
->drv_attrs
) {
478 for (i
= 0; attr_name(bus
->drv_attrs
[i
]); i
++)
479 driver_remove_file(drv
, &bus
->drv_attrs
[i
]);
483 #ifdef CONFIG_HOTPLUG
485 * Thanks to drivers making their tables __devinit, we can't allow manual
486 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
488 static int __must_check
add_bind_files(struct device_driver
*drv
)
492 ret
= driver_create_file(drv
, &driver_attr_unbind
);
494 ret
= driver_create_file(drv
, &driver_attr_bind
);
496 driver_remove_file(drv
, &driver_attr_unbind
);
501 static void remove_bind_files(struct device_driver
*drv
)
503 driver_remove_file(drv
, &driver_attr_bind
);
504 driver_remove_file(drv
, &driver_attr_unbind
);
507 static inline int add_bind_files(struct device_driver
*drv
) { return 0; }
508 static inline void remove_bind_files(struct device_driver
*drv
) {}
512 * bus_add_driver - Add a driver to the bus.
516 int bus_add_driver(struct device_driver
*drv
)
518 struct bus_type
* bus
= get_bus(drv
->bus
);
524 pr_debug("bus %s: add driver %s\n", bus
->name
, drv
->name
);
525 error
= kobject_set_name(&drv
->kobj
, "%s", drv
->name
);
528 drv
->kobj
.kset
= &bus
->drivers
;
529 if ((error
= kobject_register(&drv
->kobj
)))
532 error
= driver_attach(drv
);
535 klist_add_tail(&drv
->knode_bus
, &bus
->klist_drivers
);
536 module_add_driver(drv
->owner
, drv
);
538 error
= driver_add_attrs(bus
, drv
);
540 /* How the hell do we get out of this pickle? Give up */
541 printk(KERN_ERR
"%s: driver_add_attrs(%s) failed\n",
542 __FUNCTION__
, drv
->name
);
544 error
= add_bind_files(drv
);
547 printk(KERN_ERR
"%s: add_bind_files(%s) failed\n",
548 __FUNCTION__
, drv
->name
);
553 kobject_unregister(&drv
->kobj
);
560 * bus_remove_driver - delete driver from bus's knowledge.
563 * Detach the driver from the devices it controls, and remove
564 * it from its bus's list of drivers. Finally, we drop the reference
565 * to the bus we took in bus_add_driver().
568 void bus_remove_driver(struct device_driver
* drv
)
573 remove_bind_files(drv
);
574 driver_remove_attrs(drv
->bus
, drv
);
575 klist_remove(&drv
->knode_bus
);
576 pr_debug("bus %s: remove driver %s\n", drv
->bus
->name
, drv
->name
);
578 module_remove_driver(drv
);
579 kobject_unregister(&drv
->kobj
);
584 /* Helper for bus_rescan_devices's iter */
585 static int __must_check
bus_rescan_devices_helper(struct device
*dev
,
591 if (dev
->parent
) /* Needed for USB */
592 down(&dev
->parent
->sem
);
593 ret
= device_attach(dev
);
595 up(&dev
->parent
->sem
);
599 return ret
< 0 ? ret
: 0;
603 * bus_rescan_devices - rescan devices on the bus for possible drivers
604 * @bus: the bus to scan.
606 * This function will look for devices on the bus with no driver
607 * attached and rescan it against existing drivers to see if it matches
608 * any by calling device_attach() for the unbound devices.
610 int bus_rescan_devices(struct bus_type
* bus
)
612 return bus_for_each_dev(bus
, NULL
, NULL
, bus_rescan_devices_helper
);
616 * device_reprobe - remove driver for a device and probe for a new driver
617 * @dev: the device to reprobe
619 * This function detaches the attached driver (if any) for the given
620 * device and restarts the driver probing process. It is intended
621 * to use if probing criteria changed during a devices lifetime and
622 * driver attachment should change accordingly.
624 int device_reprobe(struct device
*dev
)
627 if (dev
->parent
) /* Needed for USB */
628 down(&dev
->parent
->sem
);
629 device_release_driver(dev
);
631 up(&dev
->parent
->sem
);
633 return bus_rescan_devices_helper(dev
, NULL
);
635 EXPORT_SYMBOL_GPL(device_reprobe
);
637 struct bus_type
*get_bus(struct bus_type
*bus
)
639 return bus
? container_of(subsys_get(&bus
->subsys
),
640 struct bus_type
, subsys
) : NULL
;
643 void put_bus(struct bus_type
* bus
)
645 subsys_put(&bus
->subsys
);
650 * find_bus - locate bus by name.
651 * @name: name of bus.
653 * Call kset_find_obj() to iterate over list of buses to
654 * find a bus by name. Return bus if found.
656 * Note that kset_find_obj increments bus' reference count.
659 struct bus_type
* find_bus(char * name
)
661 struct kobject
* k
= kset_find_obj(&bus_subsys
.kset
, name
);
662 return k
? to_bus(k
) : NULL
;
668 * bus_add_attrs - Add default attributes for this bus.
669 * @bus: Bus that has just been registered.
672 static int bus_add_attrs(struct bus_type
* bus
)
677 if (bus
->bus_attrs
) {
678 for (i
= 0; attr_name(bus
->bus_attrs
[i
]); i
++) {
679 if ((error
= bus_create_file(bus
,&bus
->bus_attrs
[i
])))
687 bus_remove_file(bus
,&bus
->bus_attrs
[i
]);
691 static void bus_remove_attrs(struct bus_type
* bus
)
695 if (bus
->bus_attrs
) {
696 for (i
= 0; attr_name(bus
->bus_attrs
[i
]); i
++)
697 bus_remove_file(bus
,&bus
->bus_attrs
[i
]);
701 static void klist_devices_get(struct klist_node
*n
)
703 struct device
*dev
= container_of(n
, struct device
, knode_bus
);
708 static void klist_devices_put(struct klist_node
*n
)
710 struct device
*dev
= container_of(n
, struct device
, knode_bus
);
716 * bus_register - register a bus with the system.
719 * Once we have that, we registered the bus with the kobject
720 * infrastructure, then register the children subsystems it has:
721 * the devices and drivers that belong to the bus.
723 int bus_register(struct bus_type
* bus
)
727 retval
= kobject_set_name(&bus
->subsys
.kset
.kobj
, "%s", bus
->name
);
731 subsys_set_kset(bus
, bus_subsys
);
732 retval
= subsystem_register(&bus
->subsys
);
736 kobject_set_name(&bus
->devices
.kobj
, "devices");
737 bus
->devices
.subsys
= &bus
->subsys
;
738 retval
= kset_register(&bus
->devices
);
740 goto bus_devices_fail
;
742 kobject_set_name(&bus
->drivers
.kobj
, "drivers");
743 bus
->drivers
.subsys
= &bus
->subsys
;
744 bus
->drivers
.ktype
= &ktype_driver
;
745 retval
= kset_register(&bus
->drivers
);
747 goto bus_drivers_fail
;
749 klist_init(&bus
->klist_devices
, klist_devices_get
, klist_devices_put
);
750 klist_init(&bus
->klist_drivers
, NULL
, NULL
);
751 retval
= bus_add_attrs(bus
);
755 pr_debug("bus type '%s' registered\n", bus
->name
);
759 kset_unregister(&bus
->drivers
);
761 kset_unregister(&bus
->devices
);
763 subsystem_unregister(&bus
->subsys
);
770 * bus_unregister - remove a bus from the system
773 * Unregister the child subsystems and the bus itself.
774 * Finally, we call put_bus() to release the refcount
776 void bus_unregister(struct bus_type
* bus
)
778 pr_debug("bus %s: unregistering\n", bus
->name
);
779 bus_remove_attrs(bus
);
780 kset_unregister(&bus
->drivers
);
781 kset_unregister(&bus
->devices
);
782 subsystem_unregister(&bus
->subsys
);
785 int __init
buses_init(void)
787 return subsystem_register(&bus_subsys
);
791 EXPORT_SYMBOL_GPL(bus_for_each_dev
);
792 EXPORT_SYMBOL_GPL(bus_find_device
);
793 EXPORT_SYMBOL_GPL(bus_for_each_drv
);
795 EXPORT_SYMBOL_GPL(bus_register
);
796 EXPORT_SYMBOL_GPL(bus_unregister
);
797 EXPORT_SYMBOL_GPL(bus_rescan_devices
);
799 EXPORT_SYMBOL_GPL(bus_create_file
);
800 EXPORT_SYMBOL_GPL(bus_remove_file
);