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)
30 static int __must_check bus_rescan_devices_helper(struct device *dev,
34 drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
36 struct driver_attribute * drv_attr = to_drv_attr(attr);
37 struct device_driver * drv = to_driver(kobj);
41 ret = drv_attr->show(drv, buf);
46 drv_attr_store(struct kobject * kobj, struct attribute * attr,
47 const char * buf, size_t count)
49 struct driver_attribute * drv_attr = to_drv_attr(attr);
50 struct device_driver * drv = to_driver(kobj);
54 ret = drv_attr->store(drv, buf, count);
58 static struct sysfs_ops driver_sysfs_ops = {
59 .show = drv_attr_show,
60 .store = drv_attr_store,
64 static void driver_release(struct kobject * kobj)
66 struct device_driver * drv = to_driver(kobj);
67 complete(&drv->unloaded);
70 static struct kobj_type ktype_driver = {
71 .sysfs_ops = &driver_sysfs_ops,
72 .release = driver_release,
77 * sysfs bindings for buses
82 bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
84 struct bus_attribute * bus_attr = to_bus_attr(attr);
85 struct bus_type * bus = to_bus(kobj);
89 ret = bus_attr->show(bus, buf);
94 bus_attr_store(struct kobject * kobj, struct attribute * attr,
95 const char * buf, size_t count)
97 struct bus_attribute * bus_attr = to_bus_attr(attr);
98 struct bus_type * bus = to_bus(kobj);
102 ret = bus_attr->store(bus, buf, count);
106 static struct sysfs_ops bus_sysfs_ops = {
107 .show = bus_attr_show,
108 .store = bus_attr_store,
111 int bus_create_file(struct bus_type * bus, struct bus_attribute * attr)
115 error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr);
122 void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
125 sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr);
130 static struct kobj_type ktype_bus = {
131 .sysfs_ops = &bus_sysfs_ops,
135 static decl_subsys(bus, &ktype_bus, NULL);
138 #ifdef CONFIG_HOTPLUG
139 /* Manually detach a device from its associated driver. */
140 static int driver_helper(struct device *dev, void *data)
142 const char *name = data;
144 if (strcmp(name, dev->bus_id) == 0)
149 static ssize_t driver_unbind(struct device_driver *drv,
150 const char *buf, size_t count)
152 struct bus_type *bus = get_bus(drv->bus);
156 dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
157 if (dev && dev->driver == drv) {
158 if (dev->parent) /* Needed for USB */
159 down(&dev->parent->sem);
160 device_release_driver(dev);
162 up(&dev->parent->sem);
169 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
172 * Manually attach a device to a driver.
173 * Note: the driver must want to bind to the device,
174 * it is not possible to override the driver's id table.
176 static ssize_t driver_bind(struct device_driver *drv,
177 const char *buf, size_t count)
179 struct bus_type *bus = get_bus(drv->bus);
183 dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
184 if (dev && dev->driver == NULL) {
185 if (dev->parent) /* Needed for USB */
186 down(&dev->parent->sem);
188 err = driver_probe_device(drv, dev);
191 up(&dev->parent->sem);
193 if (err > 0) /* success */
195 else if (err == 0) /* driver didn't accept device */
202 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
204 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
206 return sprintf(buf, "%d\n", bus->drivers_autoprobe);
209 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
210 const char *buf, size_t count)
213 bus->drivers_autoprobe = 0;
215 bus->drivers_autoprobe = 1;
219 static ssize_t store_drivers_probe(struct bus_type *bus,
220 const char *buf, size_t count)
224 dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
227 if (bus_rescan_devices_helper(dev, NULL) != 0)
233 static struct device * next_device(struct klist_iter * i)
235 struct klist_node * n = klist_next(i);
236 return n ? container_of(n, struct device, knode_bus) : NULL;
240 * bus_for_each_dev - device iterator.
242 * @start: device to start iterating from.
243 * @data: data for the callback.
244 * @fn: function to be called for each device.
246 * Iterate over @bus's list of devices, and call @fn for each,
247 * passing it @data. If @start is not NULL, we use that device to
248 * begin iterating from.
250 * We check the return of @fn each time. If it returns anything
251 * other than 0, we break out and return that value.
253 * NOTE: The device that returns a non-zero value is not retained
254 * in any way, nor is its refcount incremented. If the caller needs
255 * to retain this data, it should do, and increment the reference
256 * count in the supplied callback.
259 int bus_for_each_dev(struct bus_type * bus, struct device * start,
260 void * data, int (*fn)(struct device *, void *))
269 klist_iter_init_node(&bus->klist_devices, &i,
270 (start ? &start->knode_bus : NULL));
271 while ((dev = next_device(&i)) && !error)
272 error = fn(dev, data);
278 * bus_find_device - device iterator for locating a particular device.
280 * @start: Device to begin with
281 * @data: Data to pass to match function
282 * @match: Callback function to check device
284 * This is similar to the bus_for_each_dev() function above, but it
285 * returns a reference to a device that is 'found' for later use, as
286 * determined by the @match callback.
288 * The callback should return 0 if the device doesn't match and non-zero
289 * if it does. If the callback returns non-zero, this function will
290 * return to the caller and not iterate over any more devices.
292 struct device * bus_find_device(struct bus_type *bus,
293 struct device *start, void *data,
294 int (*match)(struct device *, void *))
302 klist_iter_init_node(&bus->klist_devices, &i,
303 (start ? &start->knode_bus : NULL));
304 while ((dev = next_device(&i)))
305 if (match(dev, data) && get_device(dev))
312 static struct device_driver * next_driver(struct klist_iter * i)
314 struct klist_node * n = klist_next(i);
315 return n ? container_of(n, struct device_driver, knode_bus) : NULL;
319 * bus_for_each_drv - driver iterator
320 * @bus: bus we're dealing with.
321 * @start: driver to start iterating on.
322 * @data: data to pass to the callback.
323 * @fn: function to call for each driver.
325 * This is nearly identical to the device iterator above.
326 * We iterate over each driver that belongs to @bus, and call
327 * @fn for each. If @fn returns anything but 0, we break out
328 * and return it. If @start is not NULL, we use it as the head
331 * NOTE: we don't return the driver that returns a non-zero
332 * value, nor do we leave the reference count incremented for that
333 * driver. If the caller needs to know that info, it must set it
334 * in the callback. It must also be sure to increment the refcount
335 * so it doesn't disappear before returning to the caller.
338 int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
339 void * data, int (*fn)(struct device_driver *, void *))
342 struct device_driver * drv;
348 klist_iter_init_node(&bus->klist_drivers, &i,
349 start ? &start->knode_bus : NULL);
350 while ((drv = next_driver(&i)) && !error)
351 error = fn(drv, data);
356 static int device_add_attrs(struct bus_type *bus, struct device *dev)
364 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
365 error = device_create_file(dev,&bus->dev_attrs[i]);
368 device_remove_file(dev, &bus->dev_attrs[i]);
375 static void device_remove_attrs(struct bus_type * bus, struct device * dev)
379 if (bus->dev_attrs) {
380 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
381 device_remove_file(dev,&bus->dev_attrs[i]);
385 #ifdef CONFIG_SYSFS_DEPRECATED
386 static int make_deprecated_bus_links(struct device *dev)
388 return sysfs_create_link(&dev->kobj,
389 &dev->bus->subsys.kset.kobj, "bus");
392 static void remove_deprecated_bus_links(struct device *dev)
394 sysfs_remove_link(&dev->kobj, "bus");
397 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
398 static inline void remove_deprecated_bus_links(struct device *dev) { }
402 * bus_add_device - add device to bus
403 * @dev: device being added
405 * - Add the device to its bus's list of devices.
406 * - Create link to device's bus.
408 int bus_add_device(struct device * dev)
410 struct bus_type * bus = get_bus(dev->bus);
414 pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
415 error = device_add_attrs(bus, dev);
418 error = sysfs_create_link(&bus->devices.kobj,
419 &dev->kobj, dev->bus_id);
422 error = sysfs_create_link(&dev->kobj,
423 &dev->bus->subsys.kset.kobj, "subsystem");
426 error = make_deprecated_bus_links(dev);
433 sysfs_remove_link(&dev->kobj, "subsystem");
435 sysfs_remove_link(&bus->devices.kobj, dev->bus_id);
437 device_remove_attrs(bus, dev);
444 * bus_attach_device - add device to bus
445 * @dev: device tried to attach to a driver
447 * - Add device to bus's list of devices.
448 * - Try to attach to driver.
450 void bus_attach_device(struct device * dev)
452 struct bus_type *bus = dev->bus;
456 dev->is_registered = 1;
457 if (bus->drivers_autoprobe)
458 ret = device_attach(dev);
461 klist_add_tail(&dev->knode_bus, &bus->klist_devices);
463 dev->is_registered = 0;
468 * bus_remove_device - remove device from bus
469 * @dev: device to be removed
471 * - Remove symlink from bus's directory.
472 * - Delete device from bus's list.
473 * - Detach from its driver.
474 * - Drop reference taken in bus_add_device().
476 void bus_remove_device(struct device * dev)
479 sysfs_remove_link(&dev->kobj, "subsystem");
480 remove_deprecated_bus_links(dev);
481 sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
482 device_remove_attrs(dev->bus, dev);
483 if (dev->is_registered) {
484 dev->is_registered = 0;
485 klist_del(&dev->knode_bus);
487 pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
488 device_release_driver(dev);
493 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
498 if (bus->drv_attrs) {
499 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
500 error = driver_create_file(drv, &bus->drv_attrs[i]);
509 driver_remove_file(drv, &bus->drv_attrs[i]);
514 static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
518 if (bus->drv_attrs) {
519 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
520 driver_remove_file(drv, &bus->drv_attrs[i]);
524 #ifdef CONFIG_HOTPLUG
526 * Thanks to drivers making their tables __devinit, we can't allow manual
527 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
529 static int __must_check add_bind_files(struct device_driver *drv)
533 ret = driver_create_file(drv, &driver_attr_unbind);
535 ret = driver_create_file(drv, &driver_attr_bind);
537 driver_remove_file(drv, &driver_attr_unbind);
542 static void remove_bind_files(struct device_driver *drv)
544 driver_remove_file(drv, &driver_attr_bind);
545 driver_remove_file(drv, &driver_attr_unbind);
548 static int add_probe_files(struct bus_type *bus)
552 bus->drivers_probe_attr.attr.name = "drivers_probe";
553 bus->drivers_probe_attr.attr.mode = S_IWUSR;
554 bus->drivers_probe_attr.attr.owner = bus->owner;
555 bus->drivers_probe_attr.store = store_drivers_probe;
556 retval = bus_create_file(bus, &bus->drivers_probe_attr);
560 bus->drivers_autoprobe_attr.attr.name = "drivers_autoprobe";
561 bus->drivers_autoprobe_attr.attr.mode = S_IWUSR | S_IRUGO;
562 bus->drivers_autoprobe_attr.attr.owner = bus->owner;
563 bus->drivers_autoprobe_attr.show = show_drivers_autoprobe;
564 bus->drivers_autoprobe_attr.store = store_drivers_autoprobe;
565 retval = bus_create_file(bus, &bus->drivers_autoprobe_attr);
567 bus_remove_file(bus, &bus->drivers_probe_attr);
572 static void remove_probe_files(struct bus_type *bus)
574 bus_remove_file(bus, &bus->drivers_autoprobe_attr);
575 bus_remove_file(bus, &bus->drivers_probe_attr);
578 static inline int add_bind_files(struct device_driver *drv) { return 0; }
579 static inline void remove_bind_files(struct device_driver *drv) {}
580 static inline int add_probe_files(struct bus_type *bus) { return 0; }
581 static inline void remove_probe_files(struct bus_type *bus) {}
585 * bus_add_driver - Add a driver to the bus.
589 int bus_add_driver(struct device_driver *drv)
591 struct bus_type * bus = get_bus(drv->bus);
597 pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
598 error = kobject_set_name(&drv->kobj, "%s", drv->name);
601 drv->kobj.kset = &bus->drivers;
602 if ((error = kobject_register(&drv->kobj)))
605 if (drv->bus->drivers_autoprobe) {
606 error = driver_attach(drv);
610 klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
611 module_add_driver(drv->owner, drv);
613 error = driver_add_attrs(bus, drv);
615 /* How the hell do we get out of this pickle? Give up */
616 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
617 __FUNCTION__, drv->name);
619 error = add_bind_files(drv);
622 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
623 __FUNCTION__, drv->name);
628 kobject_unregister(&drv->kobj);
635 * bus_remove_driver - delete driver from bus's knowledge.
638 * Detach the driver from the devices it controls, and remove
639 * it from its bus's list of drivers. Finally, we drop the reference
640 * to the bus we took in bus_add_driver().
643 void bus_remove_driver(struct device_driver * drv)
648 remove_bind_files(drv);
649 driver_remove_attrs(drv->bus, drv);
650 klist_remove(&drv->knode_bus);
651 pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
653 module_remove_driver(drv);
654 kobject_unregister(&drv->kobj);
659 /* Helper for bus_rescan_devices's iter */
660 static int __must_check bus_rescan_devices_helper(struct device *dev,
666 if (dev->parent) /* Needed for USB */
667 down(&dev->parent->sem);
668 ret = device_attach(dev);
670 up(&dev->parent->sem);
672 return ret < 0 ? ret : 0;
676 * bus_rescan_devices - rescan devices on the bus for possible drivers
677 * @bus: the bus to scan.
679 * This function will look for devices on the bus with no driver
680 * attached and rescan it against existing drivers to see if it matches
681 * any by calling device_attach() for the unbound devices.
683 int bus_rescan_devices(struct bus_type * bus)
685 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
689 * device_reprobe - remove driver for a device and probe for a new driver
690 * @dev: the device to reprobe
692 * This function detaches the attached driver (if any) for the given
693 * device and restarts the driver probing process. It is intended
694 * to use if probing criteria changed during a devices lifetime and
695 * driver attachment should change accordingly.
697 int device_reprobe(struct device *dev)
700 if (dev->parent) /* Needed for USB */
701 down(&dev->parent->sem);
702 device_release_driver(dev);
704 up(&dev->parent->sem);
706 return bus_rescan_devices_helper(dev, NULL);
708 EXPORT_SYMBOL_GPL(device_reprobe);
710 struct bus_type *get_bus(struct bus_type *bus)
712 return bus ? container_of(subsys_get(&bus->subsys),
713 struct bus_type, subsys) : NULL;
716 void put_bus(struct bus_type * bus)
718 subsys_put(&bus->subsys);
723 * find_bus - locate bus by name.
724 * @name: name of bus.
726 * Call kset_find_obj() to iterate over list of buses to
727 * find a bus by name. Return bus if found.
729 * Note that kset_find_obj increments bus' reference count.
732 struct bus_type * find_bus(char * name)
734 struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
735 return k ? to_bus(k) : NULL;
741 * bus_add_attrs - Add default attributes for this bus.
742 * @bus: Bus that has just been registered.
745 static int bus_add_attrs(struct bus_type * bus)
750 if (bus->bus_attrs) {
751 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
752 if ((error = bus_create_file(bus,&bus->bus_attrs[i])))
760 bus_remove_file(bus,&bus->bus_attrs[i]);
764 static void bus_remove_attrs(struct bus_type * bus)
768 if (bus->bus_attrs) {
769 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
770 bus_remove_file(bus,&bus->bus_attrs[i]);
774 static void klist_devices_get(struct klist_node *n)
776 struct device *dev = container_of(n, struct device, knode_bus);
781 static void klist_devices_put(struct klist_node *n)
783 struct device *dev = container_of(n, struct device, knode_bus);
789 * bus_register - register a bus with the system.
792 * Once we have that, we registered the bus with the kobject
793 * infrastructure, then register the children subsystems it has:
794 * the devices and drivers that belong to the bus.
796 int bus_register(struct bus_type * bus)
800 BLOCKING_INIT_NOTIFIER_HEAD(&bus->bus_notifier);
802 retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name);
806 subsys_set_kset(bus, bus_subsys);
807 retval = subsystem_register(&bus->subsys);
811 kobject_set_name(&bus->devices.kobj, "devices");
812 bus->devices.subsys = &bus->subsys;
813 retval = kset_register(&bus->devices);
815 goto bus_devices_fail;
817 kobject_set_name(&bus->drivers.kobj, "drivers");
818 bus->drivers.subsys = &bus->subsys;
819 bus->drivers.ktype = &ktype_driver;
820 retval = kset_register(&bus->drivers);
822 goto bus_drivers_fail;
824 klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
825 klist_init(&bus->klist_drivers, NULL, NULL);
827 bus->drivers_autoprobe = 1;
828 retval = add_probe_files(bus);
830 goto bus_probe_files_fail;
832 retval = bus_add_attrs(bus);
836 pr_debug("bus type '%s' registered\n", bus->name);
840 remove_probe_files(bus);
841 bus_probe_files_fail:
842 kset_unregister(&bus->drivers);
844 kset_unregister(&bus->devices);
846 subsystem_unregister(&bus->subsys);
852 * bus_unregister - remove a bus from the system
855 * Unregister the child subsystems and the bus itself.
856 * Finally, we call put_bus() to release the refcount
858 void bus_unregister(struct bus_type * bus)
860 pr_debug("bus %s: unregistering\n", bus->name);
861 bus_remove_attrs(bus);
862 remove_probe_files(bus);
863 kset_unregister(&bus->drivers);
864 kset_unregister(&bus->devices);
865 subsystem_unregister(&bus->subsys);
868 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
870 return blocking_notifier_chain_register(&bus->bus_notifier, nb);
872 EXPORT_SYMBOL_GPL(bus_register_notifier);
874 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
876 return blocking_notifier_chain_unregister(&bus->bus_notifier, nb);
878 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
880 int __init buses_init(void)
882 return subsystem_register(&bus_subsys);
886 EXPORT_SYMBOL_GPL(bus_for_each_dev);
887 EXPORT_SYMBOL_GPL(bus_find_device);
888 EXPORT_SYMBOL_GPL(bus_for_each_drv);
890 EXPORT_SYMBOL_GPL(bus_register);
891 EXPORT_SYMBOL_GPL(bus_unregister);
892 EXPORT_SYMBOL_GPL(bus_rescan_devices);
894 EXPORT_SYMBOL_GPL(bus_create_file);
895 EXPORT_SYMBOL_GPL(bus_remove_file);