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/config.h>
12 #include <linux/device.h>
13 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/init.h>
16 #include <linux/string.h>
18 #include "power/power.h"
20 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
21 #define to_bus(obj) container_of(obj, struct bus_type, subsys.kset.kobj)
24 * sysfs bindings for drivers
27 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
28 #define to_driver(obj) container_of(obj, struct device_driver, kobj)
32 drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
34 struct driver_attribute * drv_attr = to_drv_attr(attr);
35 struct device_driver * drv = to_driver(kobj);
39 ret = drv_attr->show(drv, buf);
44 drv_attr_store(struct kobject * kobj, struct attribute * attr,
45 const char * buf, size_t count)
47 struct driver_attribute * drv_attr = to_drv_attr(attr);
48 struct device_driver * drv = to_driver(kobj);
52 ret = drv_attr->store(drv, buf, count);
56 static struct sysfs_ops driver_sysfs_ops = {
57 .show = drv_attr_show,
58 .store = drv_attr_store,
62 static void driver_release(struct kobject * kobj)
64 struct device_driver * drv = to_driver(kobj);
65 complete(&drv->unloaded);
68 static struct kobj_type ktype_driver = {
69 .sysfs_ops = &driver_sysfs_ops,
70 .release = driver_release,
75 * sysfs bindings for buses
80 bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
82 struct bus_attribute * bus_attr = to_bus_attr(attr);
83 struct bus_type * bus = to_bus(kobj);
87 ret = bus_attr->show(bus, buf);
92 bus_attr_store(struct kobject * kobj, struct attribute * attr,
93 const char * buf, size_t count)
95 struct bus_attribute * bus_attr = to_bus_attr(attr);
96 struct bus_type * bus = to_bus(kobj);
100 ret = bus_attr->store(bus, buf, count);
104 static struct sysfs_ops bus_sysfs_ops = {
105 .show = bus_attr_show,
106 .store = bus_attr_store,
109 int bus_create_file(struct bus_type * bus, struct bus_attribute * attr)
113 error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr);
120 void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
123 sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr);
128 static struct kobj_type ktype_bus = {
129 .sysfs_ops = &bus_sysfs_ops,
133 decl_subsys(bus, &ktype_bus, NULL);
136 static struct device * next_device(struct klist_iter * i)
138 struct klist_node * n = klist_next(i);
139 return n ? container_of(n, struct device, knode_bus) : NULL;
143 * bus_for_each_dev - device iterator.
145 * @start: device to start iterating from.
146 * @data: data for the callback.
147 * @fn: function to be called for each device.
149 * Iterate over @bus's list of devices, and call @fn for each,
150 * passing it @data. If @start is not NULL, we use that device to
151 * begin iterating from.
153 * We check the return of @fn each time. If it returns anything
154 * other than 0, we break out and return that value.
156 * NOTE: The device that returns a non-zero value is not retained
157 * in any way, nor is its refcount incremented. If the caller needs
158 * to retain this data, it should do, and increment the reference
159 * count in the supplied callback.
162 int bus_for_each_dev(struct bus_type * bus, struct device * start,
163 void * data, int (*fn)(struct device *, void *))
172 klist_iter_init_node(&bus->klist_devices, &i,
173 (start ? &start->knode_bus : NULL));
174 while ((dev = next_device(&i)) && !error)
175 error = fn(dev, data);
181 * bus_find_device - device iterator for locating a particular device.
183 * @start: Device to begin with
184 * @data: Data to pass to match function
185 * @match: Callback function to check device
187 * This is similar to the bus_for_each_dev() function above, but it
188 * returns a reference to a device that is 'found' for later use, as
189 * determined by the @match callback.
191 * The callback should return 0 if the device doesn't match and non-zero
192 * if it does. If the callback returns non-zero, this function will
193 * return to the caller and not iterate over any more devices.
195 struct device * bus_find_device(struct bus_type *bus,
196 struct device *start, void *data,
197 int (*match)(struct device *, void *))
205 klist_iter_init_node(&bus->klist_devices, &i,
206 (start ? &start->knode_bus : NULL));
207 while ((dev = next_device(&i)))
208 if (match(dev, data) && get_device(dev))
215 static struct device_driver * next_driver(struct klist_iter * i)
217 struct klist_node * n = klist_next(i);
218 return n ? container_of(n, struct device_driver, knode_bus) : NULL;
222 * bus_for_each_drv - driver iterator
223 * @bus: bus we're dealing with.
224 * @start: driver to start iterating on.
225 * @data: data to pass to the callback.
226 * @fn: function to call for each driver.
228 * This is nearly identical to the device iterator above.
229 * We iterate over each driver that belongs to @bus, and call
230 * @fn for each. If @fn returns anything but 0, we break out
231 * and return it. If @start is not NULL, we use it as the head
234 * NOTE: we don't return the driver that returns a non-zero
235 * value, nor do we leave the reference count incremented for that
236 * driver. If the caller needs to know that info, it must set it
237 * in the callback. It must also be sure to increment the refcount
238 * so it doesn't disappear before returning to the caller.
241 int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
242 void * data, int (*fn)(struct device_driver *, void *))
245 struct device_driver * drv;
251 klist_iter_init_node(&bus->klist_drivers, &i,
252 start ? &start->knode_bus : NULL);
253 while ((drv = next_driver(&i)) && !error)
254 error = fn(drv, data);
259 static int device_add_attrs(struct bus_type * bus, struct device * dev)
264 if (bus->dev_attrs) {
265 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
266 error = device_create_file(dev,&bus->dev_attrs[i]);
275 device_remove_file(dev,&bus->dev_attrs[i]);
280 static void device_remove_attrs(struct bus_type * bus, struct device * dev)
284 if (bus->dev_attrs) {
285 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
286 device_remove_file(dev,&bus->dev_attrs[i]);
292 * bus_add_device - add device to bus
293 * @dev: device being added
295 * - Add the device to its bus's list of devices.
296 * - Try to attach to driver.
297 * - Create link to device's physical location.
299 int bus_add_device(struct device * dev)
301 struct bus_type * bus = get_bus(dev->bus);
305 pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
307 klist_add_tail(&bus->klist_devices, &dev->knode_bus);
308 error = device_add_attrs(bus, dev);
310 sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id);
311 sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus");
318 * bus_remove_device - remove device from bus
319 * @dev: device to be removed
321 * - Remove symlink from bus's directory.
322 * - Delete device from bus's list.
323 * - Detach from its driver.
324 * - Drop reference taken in bus_add_device().
326 void bus_remove_device(struct device * dev)
329 sysfs_remove_link(&dev->kobj, "bus");
330 sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
331 device_remove_attrs(dev->bus, dev);
332 klist_remove(&dev->knode_bus);
333 pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
334 device_release_driver(dev);
339 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
344 if (bus->drv_attrs) {
345 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
346 error = driver_create_file(drv, &bus->drv_attrs[i]);
355 driver_remove_file(drv, &bus->drv_attrs[i]);
360 static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
364 if (bus->drv_attrs) {
365 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
366 driver_remove_file(drv, &bus->drv_attrs[i]);
372 * bus_add_driver - Add a driver to the bus.
376 int bus_add_driver(struct device_driver * drv)
378 struct bus_type * bus = get_bus(drv->bus);
382 pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
383 error = kobject_set_name(&drv->kobj, "%s", drv->name);
388 drv->kobj.kset = &bus->drivers;
389 if ((error = kobject_register(&drv->kobj))) {
395 klist_add_tail(&bus->klist_drivers, &drv->knode_bus);
396 module_add_driver(drv->owner, drv);
398 driver_add_attrs(bus, drv);
405 * bus_remove_driver - delete driver from bus's knowledge.
408 * Detach the driver from the devices it controls, and remove
409 * it from its bus's list of drivers. Finally, we drop the reference
410 * to the bus we took in bus_add_driver().
413 void bus_remove_driver(struct device_driver * drv)
416 driver_remove_attrs(drv->bus, drv);
417 klist_remove(&drv->knode_bus);
418 pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
420 module_remove_driver(drv);
421 kobject_unregister(&drv->kobj);
427 /* Helper for bus_rescan_devices's iter */
428 static int bus_rescan_devices_helper(struct device *dev, void *data)
432 if (!dev->driver && (device_attach(dev) > 0))
440 * bus_rescan_devices - rescan devices on the bus for possible drivers
441 * @bus: the bus to scan.
443 * This function will look for devices on the bus with no driver
444 * attached and rescan it against existing drivers to see if it
445 * matches any. Calls device_attach(). Returns the number of devices
446 * that were sucessfully bound to a driver.
448 int bus_rescan_devices(struct bus_type * bus)
452 bus_for_each_dev(bus, NULL, &count, bus_rescan_devices_helper);
458 struct bus_type * get_bus(struct bus_type * bus)
460 return bus ? container_of(subsys_get(&bus->subsys), struct bus_type, subsys) : NULL;
463 void put_bus(struct bus_type * bus)
465 subsys_put(&bus->subsys);
470 * find_bus - locate bus by name.
471 * @name: name of bus.
473 * Call kset_find_obj() to iterate over list of buses to
474 * find a bus by name. Return bus if found.
476 * Note that kset_find_obj increments bus' reference count.
479 struct bus_type * find_bus(char * name)
481 struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
482 return k ? to_bus(k) : NULL;
487 * bus_add_attrs - Add default attributes for this bus.
488 * @bus: Bus that has just been registered.
491 static int bus_add_attrs(struct bus_type * bus)
496 if (bus->bus_attrs) {
497 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
498 if ((error = bus_create_file(bus,&bus->bus_attrs[i])))
506 bus_remove_file(bus,&bus->bus_attrs[i]);
510 static void bus_remove_attrs(struct bus_type * bus)
514 if (bus->bus_attrs) {
515 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
516 bus_remove_file(bus,&bus->bus_attrs[i]);
521 * bus_register - register a bus with the system.
524 * Once we have that, we registered the bus with the kobject
525 * infrastructure, then register the children subsystems it has:
526 * the devices and drivers that belong to the bus.
528 int bus_register(struct bus_type * bus)
532 retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name);
536 subsys_set_kset(bus, bus_subsys);
537 retval = subsystem_register(&bus->subsys);
541 kobject_set_name(&bus->devices.kobj, "devices");
542 bus->devices.subsys = &bus->subsys;
543 retval = kset_register(&bus->devices);
545 goto bus_devices_fail;
547 kobject_set_name(&bus->drivers.kobj, "drivers");
548 bus->drivers.subsys = &bus->subsys;
549 bus->drivers.ktype = &ktype_driver;
550 retval = kset_register(&bus->drivers);
552 goto bus_drivers_fail;
554 klist_init(&bus->klist_devices);
555 klist_init(&bus->klist_drivers);
558 pr_debug("bus type '%s' registered\n", bus->name);
562 kset_unregister(&bus->devices);
564 subsystem_unregister(&bus->subsys);
571 * bus_unregister - remove a bus from the system
574 * Unregister the child subsystems and the bus itself.
575 * Finally, we call put_bus() to release the refcount
577 void bus_unregister(struct bus_type * bus)
579 pr_debug("bus %s: unregistering\n", bus->name);
580 bus_remove_attrs(bus);
581 kset_unregister(&bus->drivers);
582 kset_unregister(&bus->devices);
583 subsystem_unregister(&bus->subsys);
586 int __init buses_init(void)
588 return subsystem_register(&bus_subsys);
592 EXPORT_SYMBOL_GPL(bus_for_each_dev);
593 EXPORT_SYMBOL_GPL(bus_find_device);
594 EXPORT_SYMBOL_GPL(bus_for_each_drv);
596 EXPORT_SYMBOL_GPL(bus_add_device);
597 EXPORT_SYMBOL_GPL(bus_remove_device);
598 EXPORT_SYMBOL_GPL(bus_register);
599 EXPORT_SYMBOL_GPL(bus_unregister);
600 EXPORT_SYMBOL_GPL(bus_rescan_devices);
601 EXPORT_SYMBOL_GPL(get_bus);
602 EXPORT_SYMBOL_GPL(put_bus);
603 EXPORT_SYMBOL_GPL(find_bus);
605 EXPORT_SYMBOL_GPL(bus_create_file);
606 EXPORT_SYMBOL_GPL(bus_remove_file);