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/init.h>
17 #include <linux/string.h>
19 #include "power/power.h"
21 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
22 #define to_bus(obj) container_of(obj, struct bus_type_private, subsys.kobj)
25 * sysfs bindings for drivers
28 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
31 static int __must_check bus_rescan_devices_helper(struct device *dev,
34 static struct bus_type *bus_get(struct bus_type *bus)
37 kset_get(&bus->p->subsys);
43 static void bus_put(struct bus_type *bus)
46 kset_put(&bus->p->subsys);
50 drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
52 struct driver_attribute * drv_attr = to_drv_attr(attr);
53 struct driver_private *drv_priv = to_driver(kobj);
57 ret = drv_attr->show(drv_priv->driver, buf);
62 drv_attr_store(struct kobject * kobj, struct attribute * attr,
63 const char * buf, size_t count)
65 struct driver_attribute * drv_attr = to_drv_attr(attr);
66 struct driver_private *drv_priv = to_driver(kobj);
70 ret = drv_attr->store(drv_priv->driver, buf, count);
74 static struct sysfs_ops driver_sysfs_ops = {
75 .show = drv_attr_show,
76 .store = drv_attr_store,
79 static void driver_release(struct kobject *kobj)
81 struct driver_private *drv_priv = to_driver(kobj);
83 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __FUNCTION__);
87 static struct kobj_type driver_ktype = {
88 .sysfs_ops = &driver_sysfs_ops,
89 .release = driver_release,
94 * sysfs bindings for buses
99 bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
101 struct bus_attribute * bus_attr = to_bus_attr(attr);
102 struct bus_type_private *bus_priv = to_bus(kobj);
106 ret = bus_attr->show(bus_priv->bus, buf);
111 bus_attr_store(struct kobject * kobj, struct attribute * attr,
112 const char * buf, size_t count)
114 struct bus_attribute * bus_attr = to_bus_attr(attr);
115 struct bus_type_private *bus_priv = to_bus(kobj);
119 ret = bus_attr->store(bus_priv->bus, buf, count);
123 static struct sysfs_ops bus_sysfs_ops = {
124 .show = bus_attr_show,
125 .store = bus_attr_store,
128 int bus_create_file(struct bus_type * bus, struct bus_attribute * attr)
132 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
139 void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
142 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
147 static struct kobj_type bus_ktype = {
148 .sysfs_ops = &bus_sysfs_ops,
151 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
153 struct kobj_type *ktype = get_ktype(kobj);
155 if (ktype == &bus_ktype)
160 static struct kset_uevent_ops bus_uevent_ops = {
161 .filter = bus_uevent_filter,
164 static struct kset *bus_kset;
167 #ifdef CONFIG_HOTPLUG
168 /* Manually detach a device from its associated driver. */
169 static int driver_helper(struct device *dev, void *data)
171 const char *name = data;
173 if (strcmp(name, dev->bus_id) == 0)
178 static ssize_t driver_unbind(struct device_driver *drv,
179 const char *buf, size_t count)
181 struct bus_type *bus = bus_get(drv->bus);
185 dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
186 if (dev && dev->driver == drv) {
187 if (dev->parent) /* Needed for USB */
188 down(&dev->parent->sem);
189 device_release_driver(dev);
191 up(&dev->parent->sem);
198 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
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 driver_bind(struct device_driver *drv,
206 const char *buf, size_t count)
208 struct bus_type *bus = bus_get(drv->bus);
212 dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
213 if (dev && dev->driver == NULL) {
214 if (dev->parent) /* Needed for USB */
215 down(&dev->parent->sem);
217 err = driver_probe_device(drv, dev);
220 up(&dev->parent->sem);
222 if (err > 0) /* success */
224 else if (err == 0) /* driver didn't accept device */
231 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
233 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
235 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
238 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
239 const char *buf, size_t count)
242 bus->p->drivers_autoprobe = 0;
244 bus->p->drivers_autoprobe = 1;
248 static ssize_t store_drivers_probe(struct bus_type *bus,
249 const char *buf, size_t count)
253 dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
256 if (bus_rescan_devices_helper(dev, NULL) != 0)
262 static struct device * next_device(struct klist_iter * i)
264 struct klist_node * n = klist_next(i);
265 return n ? container_of(n, struct device, knode_bus) : NULL;
269 * bus_for_each_dev - device iterator.
271 * @start: device to start iterating from.
272 * @data: data for the callback.
273 * @fn: function to be called for each device.
275 * Iterate over @bus's list of devices, and call @fn for each,
276 * passing it @data. If @start is not NULL, we use that device to
277 * begin iterating from.
279 * We check the return of @fn each time. If it returns anything
280 * other than 0, we break out and return that value.
282 * NOTE: The device that returns a non-zero value is not retained
283 * in any way, nor is its refcount incremented. If the caller needs
284 * to retain this data, it should do, and increment the reference
285 * 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->knode_bus : NULL));
300 while ((dev = next_device(&i)) && !error)
301 error = fn(dev, data);
307 * bus_find_device - device iterator for locating a particular device.
309 * @start: Device to begin with
310 * @data: Data to pass to match function
311 * @match: Callback function to check device
313 * This is similar to the bus_for_each_dev() function above, but it
314 * returns a reference to a device that is 'found' for later use, as
315 * determined by the @match callback.
317 * The callback should return 0 if the device doesn't match and non-zero
318 * if it does. If the callback returns non-zero, this function will
319 * return to the caller and not iterate over any more devices.
321 struct device * bus_find_device(struct bus_type *bus,
322 struct device *start, void *data,
323 int (*match)(struct device *, void *))
331 klist_iter_init_node(&bus->p->klist_devices, &i,
332 (start ? &start->knode_bus : NULL));
333 while ((dev = next_device(&i)))
334 if (match(dev, data) && get_device(dev))
341 static struct device_driver * next_driver(struct klist_iter * i)
343 struct klist_node * n = klist_next(i);
344 struct driver_private *drv_priv;
347 drv_priv = container_of(n, struct driver_private, knode_bus);
348 return drv_priv->driver;
354 * bus_for_each_drv - driver iterator
355 * @bus: bus we're dealing with.
356 * @start: driver to start iterating on.
357 * @data: data to pass to the callback.
358 * @fn: function to call for each driver.
360 * This is nearly identical to the device iterator above.
361 * We iterate over each driver that belongs to @bus, and call
362 * @fn for each. If @fn returns anything but 0, we break out
363 * and return it. If @start is not NULL, we use it as the head
366 * NOTE: we don't return the driver that returns a non-zero
367 * value, nor do we leave the reference count incremented for that
368 * driver. If the caller needs to know that info, it must set it
369 * in the callback. It must also be sure to increment the refcount
370 * so it doesn't disappear before returning to the caller.
373 int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
374 void * data, int (*fn)(struct device_driver *, void *))
377 struct device_driver * drv;
383 klist_iter_init_node(&bus->p->klist_drivers, &i,
384 start ? &start->p->knode_bus : NULL);
385 while ((drv = next_driver(&i)) && !error)
386 error = fn(drv, data);
391 static int device_add_attrs(struct bus_type *bus, struct device *dev)
399 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
400 error = device_create_file(dev,&bus->dev_attrs[i]);
403 device_remove_file(dev, &bus->dev_attrs[i]);
410 static void device_remove_attrs(struct bus_type * bus, struct device * dev)
414 if (bus->dev_attrs) {
415 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
416 device_remove_file(dev,&bus->dev_attrs[i]);
420 #ifdef CONFIG_SYSFS_DEPRECATED
421 static int make_deprecated_bus_links(struct device *dev)
423 return sysfs_create_link(&dev->kobj,
424 &dev->bus->p->subsys.kobj, "bus");
427 static void remove_deprecated_bus_links(struct device *dev)
429 sysfs_remove_link(&dev->kobj, "bus");
432 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
433 static inline void remove_deprecated_bus_links(struct device *dev) { }
437 * bus_add_device - add device to bus
438 * @dev: device being added
440 * - Add the device to its bus's list of devices.
441 * - Create link to device's bus.
443 int bus_add_device(struct device * dev)
445 struct bus_type * bus = bus_get(dev->bus);
449 pr_debug("bus: '%s': add device %s\n", bus->name, dev->bus_id);
450 error = device_add_attrs(bus, dev);
453 error = sysfs_create_link(&bus->p->devices_kset->kobj,
454 &dev->kobj, dev->bus_id);
457 error = sysfs_create_link(&dev->kobj,
458 &dev->bus->p->subsys.kobj, "subsystem");
461 error = make_deprecated_bus_links(dev);
468 sysfs_remove_link(&dev->kobj, "subsystem");
470 sysfs_remove_link(&bus->p->devices_kset->kobj, dev->bus_id);
472 device_remove_attrs(bus, dev);
479 * bus_attach_device - add device to bus
480 * @dev: device tried to attach to a driver
482 * - Add device to bus's list of devices.
483 * - Try to attach to driver.
485 void bus_attach_device(struct device * dev)
487 struct bus_type *bus = dev->bus;
491 dev->is_registered = 1;
492 if (bus->p->drivers_autoprobe)
493 ret = device_attach(dev);
496 klist_add_tail(&dev->knode_bus, &bus->p->klist_devices);
498 dev->is_registered = 0;
503 * bus_remove_device - remove device from bus
504 * @dev: device to be removed
506 * - Remove symlink from bus's directory.
507 * - Delete device from bus's list.
508 * - Detach from its driver.
509 * - Drop reference taken in bus_add_device().
511 void bus_remove_device(struct device * dev)
514 sysfs_remove_link(&dev->kobj, "subsystem");
515 remove_deprecated_bus_links(dev);
516 sysfs_remove_link(&dev->bus->p->devices_kset->kobj, dev->bus_id);
517 device_remove_attrs(dev->bus, dev);
518 if (dev->is_registered) {
519 dev->is_registered = 0;
520 klist_del(&dev->knode_bus);
522 pr_debug("bus: '%s': remove device %s\n", dev->bus->name, dev->bus_id);
523 device_release_driver(dev);
528 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
533 if (bus->drv_attrs) {
534 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
535 error = driver_create_file(drv, &bus->drv_attrs[i]);
544 driver_remove_file(drv, &bus->drv_attrs[i]);
549 static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
553 if (bus->drv_attrs) {
554 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
555 driver_remove_file(drv, &bus->drv_attrs[i]);
559 #ifdef CONFIG_HOTPLUG
561 * Thanks to drivers making their tables __devinit, we can't allow manual
562 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
564 static int __must_check add_bind_files(struct device_driver *drv)
568 ret = driver_create_file(drv, &driver_attr_unbind);
570 ret = driver_create_file(drv, &driver_attr_bind);
572 driver_remove_file(drv, &driver_attr_unbind);
577 static void remove_bind_files(struct device_driver *drv)
579 driver_remove_file(drv, &driver_attr_bind);
580 driver_remove_file(drv, &driver_attr_unbind);
583 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
584 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
585 show_drivers_autoprobe, store_drivers_autoprobe);
587 static int add_probe_files(struct bus_type *bus)
591 retval = bus_create_file(bus, &bus_attr_drivers_probe);
595 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
597 bus_remove_file(bus, &bus_attr_drivers_probe);
602 static void remove_probe_files(struct bus_type *bus)
604 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
605 bus_remove_file(bus, &bus_attr_drivers_probe);
608 static inline int add_bind_files(struct device_driver *drv) { return 0; }
609 static inline void remove_bind_files(struct device_driver *drv) {}
610 static inline int add_probe_files(struct bus_type *bus) { return 0; }
611 static inline void remove_probe_files(struct bus_type *bus) {}
614 static ssize_t driver_uevent_store(struct device_driver *drv,
615 const char *buf, size_t count)
617 enum kobject_action action;
619 if (kobject_action_type(buf, count, &action) == 0)
620 kobject_uevent(&drv->p->kobj, action);
623 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
626 * bus_add_driver - Add a driver to the bus.
630 int bus_add_driver(struct device_driver *drv)
632 struct bus_type *bus;
633 struct driver_private *priv;
636 bus = bus_get(drv->bus);
640 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
642 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
646 error = kobject_set_name(&priv->kobj, "%s", drv->name);
649 priv->kobj.kset = bus->p->drivers_kset;
650 priv->kobj.ktype = &driver_ktype;
651 klist_init(&priv->klist_devices, NULL, NULL);
654 error = kobject_register(&priv->kobj);
658 if (drv->bus->p->drivers_autoprobe) {
659 error = driver_attach(drv);
663 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
664 module_add_driver(drv->owner, drv);
666 error = driver_create_file(drv, &driver_attr_uevent);
668 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
669 __FUNCTION__, drv->name);
671 error = driver_add_attrs(bus, drv);
673 /* How the hell do we get out of this pickle? Give up */
674 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
675 __FUNCTION__, drv->name);
677 error = add_bind_files(drv);
680 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
681 __FUNCTION__, drv->name);
686 kobject_unregister(&priv->kobj);
693 * bus_remove_driver - delete driver from bus's knowledge.
696 * Detach the driver from the devices it controls, and remove
697 * it from its bus's list of drivers. Finally, we drop the reference
698 * to the bus we took in bus_add_driver().
701 void bus_remove_driver(struct device_driver * drv)
706 remove_bind_files(drv);
707 driver_remove_attrs(drv->bus, drv);
708 driver_remove_file(drv, &driver_attr_uevent);
709 klist_remove(&drv->p->knode_bus);
710 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
712 module_remove_driver(drv);
713 kobject_unregister(&drv->p->kobj);
718 /* Helper for bus_rescan_devices's iter */
719 static int __must_check bus_rescan_devices_helper(struct device *dev,
725 if (dev->parent) /* Needed for USB */
726 down(&dev->parent->sem);
727 ret = device_attach(dev);
729 up(&dev->parent->sem);
731 return ret < 0 ? ret : 0;
735 * bus_rescan_devices - rescan devices on the bus for possible drivers
736 * @bus: the bus to scan.
738 * This function will look for devices on the bus with no driver
739 * attached and rescan it against existing drivers to see if it matches
740 * any by calling device_attach() for the unbound devices.
742 int bus_rescan_devices(struct bus_type * bus)
744 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
748 * device_reprobe - remove driver for a device and probe for a new driver
749 * @dev: the device to reprobe
751 * This function detaches the attached driver (if any) for the given
752 * device and restarts the driver probing process. It is intended
753 * to use if probing criteria changed during a devices lifetime and
754 * driver attachment should change accordingly.
756 int device_reprobe(struct device *dev)
759 if (dev->parent) /* Needed for USB */
760 down(&dev->parent->sem);
761 device_release_driver(dev);
763 up(&dev->parent->sem);
765 return bus_rescan_devices_helper(dev, NULL);
767 EXPORT_SYMBOL_GPL(device_reprobe);
770 * find_bus - locate bus by name.
771 * @name: name of bus.
773 * Call kset_find_obj() to iterate over list of buses to
774 * find a bus by name. Return bus if found.
776 * Note that kset_find_obj increments bus' reference count.
779 struct bus_type * find_bus(char * name)
781 struct kobject * k = kset_find_obj(bus_kset, name);
782 return k ? to_bus(k) : NULL;
788 * bus_add_attrs - Add default attributes for this bus.
789 * @bus: Bus that has just been registered.
792 static int bus_add_attrs(struct bus_type * bus)
797 if (bus->bus_attrs) {
798 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
799 error = bus_create_file(bus,&bus->bus_attrs[i]);
808 bus_remove_file(bus,&bus->bus_attrs[i]);
812 static void bus_remove_attrs(struct bus_type * bus)
816 if (bus->bus_attrs) {
817 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
818 bus_remove_file(bus,&bus->bus_attrs[i]);
822 static void klist_devices_get(struct klist_node *n)
824 struct device *dev = container_of(n, struct device, knode_bus);
829 static void klist_devices_put(struct klist_node *n)
831 struct device *dev = container_of(n, struct device, knode_bus);
836 static ssize_t bus_uevent_store(struct bus_type *bus,
837 const char *buf, size_t count)
839 enum kobject_action action;
841 if (kobject_action_type(buf, count, &action) == 0)
842 kobject_uevent(&bus->p->subsys.kobj, action);
845 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
848 * bus_register - register a bus with the system.
851 * Once we have that, we registered the bus with the kobject
852 * infrastructure, then register the children subsystems it has:
853 * the devices and drivers that belong to the bus.
855 int bus_register(struct bus_type * bus)
858 struct bus_type_private *priv;
860 priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
867 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
869 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
873 priv->subsys.kobj.kset = bus_kset;
874 priv->subsys.kobj.ktype = &bus_ktype;
875 priv->drivers_autoprobe = 1;
877 retval = kset_register(&priv->subsys);
881 retval = bus_create_file(bus, &bus_attr_uevent);
883 goto bus_uevent_fail;
885 priv->devices_kset = kset_create_and_add("devices", NULL,
887 if (!priv->devices_kset) {
889 goto bus_devices_fail;
892 priv->drivers_kset = kset_create_and_add("drivers", NULL,
894 if (!priv->drivers_kset) {
896 goto bus_drivers_fail;
899 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
900 klist_init(&priv->klist_drivers, NULL, NULL);
902 retval = add_probe_files(bus);
904 goto bus_probe_files_fail;
906 retval = bus_add_attrs(bus);
910 pr_debug("bus: '%s': registered\n", bus->name);
914 remove_probe_files(bus);
915 bus_probe_files_fail:
916 kset_unregister(bus->p->drivers_kset);
918 kset_unregister(bus->p->devices_kset);
920 bus_remove_file(bus, &bus_attr_uevent);
922 kset_unregister(&bus->p->subsys);
929 * bus_unregister - remove a bus from the system
932 * Unregister the child subsystems and the bus itself.
933 * Finally, we call bus_put() to release the refcount
935 void bus_unregister(struct bus_type * bus)
937 pr_debug("bus: '%s': unregistering\n", bus->name);
938 bus_remove_attrs(bus);
939 remove_probe_files(bus);
940 kset_unregister(bus->p->drivers_kset);
941 kset_unregister(bus->p->devices_kset);
942 bus_remove_file(bus, &bus_attr_uevent);
943 kset_unregister(&bus->p->subsys);
947 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
949 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
951 EXPORT_SYMBOL_GPL(bus_register_notifier);
953 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
955 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
957 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
959 struct kset *bus_get_kset(struct bus_type *bus)
961 return &bus->p->subsys;
963 EXPORT_SYMBOL_GPL(bus_get_kset);
965 struct klist *bus_get_device_klist(struct bus_type *bus)
967 return &bus->p->klist_devices;
969 EXPORT_SYMBOL_GPL(bus_get_device_klist);
971 int __init buses_init(void)
973 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
980 EXPORT_SYMBOL_GPL(bus_for_each_dev);
981 EXPORT_SYMBOL_GPL(bus_find_device);
982 EXPORT_SYMBOL_GPL(bus_for_each_drv);
984 EXPORT_SYMBOL_GPL(bus_register);
985 EXPORT_SYMBOL_GPL(bus_unregister);
986 EXPORT_SYMBOL_GPL(bus_rescan_devices);
988 EXPORT_SYMBOL_GPL(bus_create_file);
989 EXPORT_SYMBOL_GPL(bus_remove_file);