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 * bus_attach_device - add device to bus
393 * @dev: device tried to attach to a driver
395 * - Try to attach to driver.
397 int bus_attach_device(struct device * dev)
399 struct bus_type *bus = dev->bus;
403 ret = device_attach(dev);
405 klist_add_tail(&dev->knode_bus, &bus->klist_devices);
413 * bus_remove_device - remove device from bus
414 * @dev: device to be removed
416 * - Remove symlink from bus's directory.
417 * - Delete device from bus's list.
418 * - Detach from its driver.
419 * - Drop reference taken in bus_add_device().
421 void bus_remove_device(struct device * dev)
424 sysfs_remove_link(&dev->kobj, "subsystem");
425 sysfs_remove_link(&dev->kobj, "bus");
426 sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
427 device_remove_attrs(dev->bus, dev);
428 klist_remove(&dev->knode_bus);
429 pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
430 device_release_driver(dev);
435 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
440 if (bus->drv_attrs) {
441 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
442 error = driver_create_file(drv, &bus->drv_attrs[i]);
451 driver_remove_file(drv, &bus->drv_attrs[i]);
456 static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
460 if (bus->drv_attrs) {
461 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
462 driver_remove_file(drv, &bus->drv_attrs[i]);
466 #ifdef CONFIG_HOTPLUG
468 * Thanks to drivers making their tables __devinit, we can't allow manual
469 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
471 static int __must_check add_bind_files(struct device_driver *drv)
475 ret = driver_create_file(drv, &driver_attr_unbind);
477 ret = driver_create_file(drv, &driver_attr_bind);
479 driver_remove_file(drv, &driver_attr_unbind);
484 static void remove_bind_files(struct device_driver *drv)
486 driver_remove_file(drv, &driver_attr_bind);
487 driver_remove_file(drv, &driver_attr_unbind);
490 static inline int add_bind_files(struct device_driver *drv) { return 0; }
491 static inline void remove_bind_files(struct device_driver *drv) {}
495 * bus_add_driver - Add a driver to the bus.
499 int bus_add_driver(struct device_driver *drv)
501 struct bus_type * bus = get_bus(drv->bus);
505 pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
506 error = kobject_set_name(&drv->kobj, "%s", drv->name);
509 drv->kobj.kset = &bus->drivers;
510 if ((error = kobject_register(&drv->kobj)))
513 error = driver_attach(drv);
516 klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
517 module_add_driver(drv->owner, drv);
519 error = driver_add_attrs(bus, drv);
521 /* How the hell do we get out of this pickle? Give up */
522 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
523 __FUNCTION__, drv->name);
525 error = add_bind_files(drv);
528 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
529 __FUNCTION__, drv->name);
534 kobject_unregister(&drv->kobj);
541 * bus_remove_driver - delete driver from bus's knowledge.
544 * Detach the driver from the devices it controls, and remove
545 * it from its bus's list of drivers. Finally, we drop the reference
546 * to the bus we took in bus_add_driver().
549 void bus_remove_driver(struct device_driver * drv)
552 remove_bind_files(drv);
553 driver_remove_attrs(drv->bus, drv);
554 klist_remove(&drv->knode_bus);
555 pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
557 module_remove_driver(drv);
558 kobject_unregister(&drv->kobj);
564 /* Helper for bus_rescan_devices's iter */
565 static int __must_check bus_rescan_devices_helper(struct device *dev,
571 if (dev->parent) /* Needed for USB */
572 down(&dev->parent->sem);
573 ret = device_attach(dev);
575 up(&dev->parent->sem);
579 return ret < 0 ? ret : 0;
583 * bus_rescan_devices - rescan devices on the bus for possible drivers
584 * @bus: the bus to scan.
586 * This function will look for devices on the bus with no driver
587 * attached and rescan it against existing drivers to see if it matches
588 * any by calling device_attach() for the unbound devices.
590 int bus_rescan_devices(struct bus_type * bus)
592 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
596 * device_reprobe - remove driver for a device and probe for a new driver
597 * @dev: the device to reprobe
599 * This function detaches the attached driver (if any) for the given
600 * device and restarts the driver probing process. It is intended
601 * to use if probing criteria changed during a devices lifetime and
602 * driver attachment should change accordingly.
604 int device_reprobe(struct device *dev)
607 if (dev->parent) /* Needed for USB */
608 down(&dev->parent->sem);
609 device_release_driver(dev);
611 up(&dev->parent->sem);
613 return bus_rescan_devices_helper(dev, NULL);
615 EXPORT_SYMBOL_GPL(device_reprobe);
617 struct bus_type *get_bus(struct bus_type *bus)
619 return bus ? container_of(subsys_get(&bus->subsys),
620 struct bus_type, subsys) : NULL;
623 void put_bus(struct bus_type * bus)
625 subsys_put(&bus->subsys);
630 * find_bus - locate bus by name.
631 * @name: name of bus.
633 * Call kset_find_obj() to iterate over list of buses to
634 * find a bus by name. Return bus if found.
636 * Note that kset_find_obj increments bus' reference count.
639 struct bus_type * find_bus(char * name)
641 struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
642 return k ? to_bus(k) : NULL;
648 * bus_add_attrs - Add default attributes for this bus.
649 * @bus: Bus that has just been registered.
652 static int bus_add_attrs(struct bus_type * bus)
657 if (bus->bus_attrs) {
658 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
659 if ((error = bus_create_file(bus,&bus->bus_attrs[i])))
667 bus_remove_file(bus,&bus->bus_attrs[i]);
671 static void bus_remove_attrs(struct bus_type * bus)
675 if (bus->bus_attrs) {
676 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
677 bus_remove_file(bus,&bus->bus_attrs[i]);
681 static void klist_devices_get(struct klist_node *n)
683 struct device *dev = container_of(n, struct device, knode_bus);
688 static void klist_devices_put(struct klist_node *n)
690 struct device *dev = container_of(n, struct device, knode_bus);
695 static void klist_drivers_get(struct klist_node *n)
697 struct device_driver *drv = container_of(n, struct device_driver,
703 static void klist_drivers_put(struct klist_node *n)
705 struct device_driver *drv = container_of(n, struct device_driver,
712 * bus_register - register a bus with the system.
715 * Once we have that, we registered the bus with the kobject
716 * infrastructure, then register the children subsystems it has:
717 * the devices and drivers that belong to the bus.
719 int bus_register(struct bus_type * bus)
723 retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name);
727 subsys_set_kset(bus, bus_subsys);
728 retval = subsystem_register(&bus->subsys);
732 kobject_set_name(&bus->devices.kobj, "devices");
733 bus->devices.subsys = &bus->subsys;
734 retval = kset_register(&bus->devices);
736 goto bus_devices_fail;
738 kobject_set_name(&bus->drivers.kobj, "drivers");
739 bus->drivers.subsys = &bus->subsys;
740 bus->drivers.ktype = &ktype_driver;
741 retval = kset_register(&bus->drivers);
743 goto bus_drivers_fail;
745 klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
746 klist_init(&bus->klist_drivers, klist_drivers_get, klist_drivers_put);
749 pr_debug("bus type '%s' registered\n", bus->name);
753 kset_unregister(&bus->devices);
755 subsystem_unregister(&bus->subsys);
762 * bus_unregister - remove a bus from the system
765 * Unregister the child subsystems and the bus itself.
766 * Finally, we call put_bus() to release the refcount
768 void bus_unregister(struct bus_type * bus)
770 pr_debug("bus %s: unregistering\n", bus->name);
771 bus_remove_attrs(bus);
772 kset_unregister(&bus->drivers);
773 kset_unregister(&bus->devices);
774 subsystem_unregister(&bus->subsys);
777 int __init buses_init(void)
779 return subsystem_register(&bus_subsys);
783 EXPORT_SYMBOL_GPL(bus_for_each_dev);
784 EXPORT_SYMBOL_GPL(bus_find_device);
785 EXPORT_SYMBOL_GPL(bus_for_each_drv);
787 EXPORT_SYMBOL_GPL(bus_register);
788 EXPORT_SYMBOL_GPL(bus_unregister);
789 EXPORT_SYMBOL_GPL(bus_rescan_devices);
791 EXPORT_SYMBOL_GPL(bus_create_file);
792 EXPORT_SYMBOL_GPL(bus_remove_file);