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[hh.org.git] / drivers / base / bus.c
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1 /*
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
9 */
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>
16 #include "base.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 ssize_t
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);
35 ssize_t ret = -EIO;
37 if (drv_attr->show)
38 ret = drv_attr->show(drv, buf);
39 return ret;
42 static ssize_t
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);
48 ssize_t ret = -EIO;
50 if (drv_attr->store)
51 ret = drv_attr->store(drv, buf, count);
52 return ret;
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
78 static ssize_t
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);
83 ssize_t ret = 0;
85 if (bus_attr->show)
86 ret = bus_attr->show(bus, buf);
87 return ret;
90 static ssize_t
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);
96 ssize_t ret = 0;
98 if (bus_attr->store)
99 ret = bus_attr->store(bus, buf, count);
100 return ret;
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)
110 int error;
111 if (get_bus(bus)) {
112 error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr);
113 put_bus(bus);
114 } else
115 error = -EINVAL;
116 return error;
119 void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
121 if (get_bus(bus)) {
122 sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr);
123 put_bus(bus);
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)
143 return 1;
144 return 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);
151 struct device *dev;
152 int err = -ENODEV;
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);
159 if (dev->parent)
160 up(&dev->parent->sem);
161 err = count;
163 put_device(dev);
164 put_bus(bus);
165 return err;
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);
178 struct device *dev;
179 int err = -ENODEV;
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);
185 down(&dev->sem);
186 err = driver_probe_device(drv, dev);
187 up(&dev->sem);
188 if (dev->parent)
189 up(&dev->parent->sem);
191 if (err > 0) /* success */
192 err = count;
193 else if (err == 0) /* driver didn't accept device */
194 err = -ENODEV;
196 put_device(dev);
197 put_bus(bus);
198 return err;
200 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
202 #endif
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.
212 * @bus: bus type.
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 *))
233 struct klist_iter i;
234 struct device * dev;
235 int error = 0;
237 if (!bus)
238 return -EINVAL;
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);
244 klist_iter_exit(&i);
245 return error;
249 * bus_find_device - device iterator for locating a particular device.
250 * @bus: bus type
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 *))
267 struct klist_iter i;
268 struct device *dev;
270 if (!bus)
271 return NULL;
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))
277 break;
278 klist_iter_exit(&i);
279 return 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
300 * of the list.
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 *))
312 struct klist_iter i;
313 struct device_driver * drv;
314 int error = 0;
316 if (!bus)
317 return -EINVAL;
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);
323 klist_iter_exit(&i);
324 return error;
327 static int device_add_attrs(struct bus_type * bus, struct device * dev)
329 int error = 0;
330 int i;
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]);
335 if (error)
336 goto Err;
339 Done:
340 return error;
341 Err:
342 while (--i >= 0)
343 device_remove_file(dev,&bus->dev_attrs[i]);
344 goto Done;
348 static void device_remove_attrs(struct bus_type * bus, struct device * dev)
350 int i;
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]);
358 #ifdef CONFIG_SYSFS_DEPRECATED
359 static int make_deprecated_bus_links(struct device *dev)
361 return sysfs_create_link(&dev->kobj,
362 &dev->bus->subsys.kset.kobj, "bus");
365 static void remove_deprecated_bus_links(struct device *dev)
367 sysfs_remove_link(&dev->kobj, "bus");
369 #else
370 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
371 static inline void remove_deprecated_bus_links(struct device *dev) { }
372 #endif
375 * bus_add_device - add device to bus
376 * @dev: device being added
378 * - Add the device to its bus's list of devices.
379 * - Create link to device's bus.
381 int bus_add_device(struct device * dev)
383 struct bus_type * bus = get_bus(dev->bus);
384 int error = 0;
386 if (bus) {
387 pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
388 error = device_add_attrs(bus, dev);
389 if (error)
390 goto out_put;
391 error = sysfs_create_link(&bus->devices.kobj,
392 &dev->kobj, dev->bus_id);
393 if (error)
394 goto out_id;
395 error = sysfs_create_link(&dev->kobj,
396 &dev->bus->subsys.kset.kobj, "subsystem");
397 if (error)
398 goto out_subsys;
399 error = make_deprecated_bus_links(dev);
400 if (error)
401 goto out_deprecated;
403 return 0;
405 out_deprecated:
406 sysfs_remove_link(&dev->kobj, "subsystem");
407 out_subsys:
408 sysfs_remove_link(&bus->devices.kobj, dev->bus_id);
409 out_id:
410 device_remove_attrs(bus, dev);
411 out_put:
412 put_bus(dev->bus);
413 return error;
417 * bus_attach_device - add device to bus
418 * @dev: device tried to attach to a driver
420 * - Add device to bus's list of devices.
421 * - Try to attach to driver.
423 int bus_attach_device(struct device * dev)
425 struct bus_type *bus = dev->bus;
426 int ret = 0;
428 if (bus) {
429 dev->is_registered = 1;
430 ret = device_attach(dev);
431 if (ret >= 0) {
432 klist_add_tail(&dev->knode_bus, &bus->klist_devices);
433 ret = 0;
434 } else
435 dev->is_registered = 0;
437 return ret;
441 * bus_remove_device - remove device from bus
442 * @dev: device to be removed
444 * - Remove symlink from bus's directory.
445 * - Delete device from bus's list.
446 * - Detach from its driver.
447 * - Drop reference taken in bus_add_device().
449 void bus_remove_device(struct device * dev)
451 if (dev->bus) {
452 sysfs_remove_link(&dev->kobj, "subsystem");
453 remove_deprecated_bus_links(dev);
454 sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
455 device_remove_attrs(dev->bus, dev);
456 if (dev->is_registered) {
457 dev->is_registered = 0;
458 klist_del(&dev->knode_bus);
460 pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
461 device_release_driver(dev);
462 put_bus(dev->bus);
466 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
468 int error = 0;
469 int i;
471 if (bus->drv_attrs) {
472 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
473 error = driver_create_file(drv, &bus->drv_attrs[i]);
474 if (error)
475 goto Err;
478 Done:
479 return error;
480 Err:
481 while (--i >= 0)
482 driver_remove_file(drv, &bus->drv_attrs[i]);
483 goto Done;
487 static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
489 int i;
491 if (bus->drv_attrs) {
492 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
493 driver_remove_file(drv, &bus->drv_attrs[i]);
497 #ifdef CONFIG_HOTPLUG
499 * Thanks to drivers making their tables __devinit, we can't allow manual
500 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
502 static int __must_check add_bind_files(struct device_driver *drv)
504 int ret;
506 ret = driver_create_file(drv, &driver_attr_unbind);
507 if (ret == 0) {
508 ret = driver_create_file(drv, &driver_attr_bind);
509 if (ret)
510 driver_remove_file(drv, &driver_attr_unbind);
512 return ret;
515 static void remove_bind_files(struct device_driver *drv)
517 driver_remove_file(drv, &driver_attr_bind);
518 driver_remove_file(drv, &driver_attr_unbind);
520 #else
521 static inline int add_bind_files(struct device_driver *drv) { return 0; }
522 static inline void remove_bind_files(struct device_driver *drv) {}
523 #endif
526 * bus_add_driver - Add a driver to the bus.
527 * @drv: driver.
530 int bus_add_driver(struct device_driver *drv)
532 struct bus_type * bus = get_bus(drv->bus);
533 int error = 0;
535 if (!bus)
536 return 0;
538 pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
539 error = kobject_set_name(&drv->kobj, "%s", drv->name);
540 if (error)
541 goto out_put_bus;
542 drv->kobj.kset = &bus->drivers;
543 if ((error = kobject_register(&drv->kobj)))
544 goto out_put_bus;
546 error = driver_attach(drv);
547 if (error)
548 goto out_unregister;
549 klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
550 module_add_driver(drv->owner, drv);
552 error = driver_add_attrs(bus, drv);
553 if (error) {
554 /* How the hell do we get out of this pickle? Give up */
555 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
556 __FUNCTION__, drv->name);
558 error = add_bind_files(drv);
559 if (error) {
560 /* Ditto */
561 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
562 __FUNCTION__, drv->name);
565 return error;
566 out_unregister:
567 kobject_unregister(&drv->kobj);
568 out_put_bus:
569 put_bus(bus);
570 return error;
574 * bus_remove_driver - delete driver from bus's knowledge.
575 * @drv: driver.
577 * Detach the driver from the devices it controls, and remove
578 * it from its bus's list of drivers. Finally, we drop the reference
579 * to the bus we took in bus_add_driver().
582 void bus_remove_driver(struct device_driver * drv)
584 if (!drv->bus)
585 return;
587 remove_bind_files(drv);
588 driver_remove_attrs(drv->bus, drv);
589 klist_remove(&drv->knode_bus);
590 pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
591 driver_detach(drv);
592 module_remove_driver(drv);
593 kobject_unregister(&drv->kobj);
594 put_bus(drv->bus);
598 /* Helper for bus_rescan_devices's iter */
599 static int __must_check bus_rescan_devices_helper(struct device *dev,
600 void *data)
602 int ret = 0;
604 if (!dev->driver) {
605 if (dev->parent) /* Needed for USB */
606 down(&dev->parent->sem);
607 ret = device_attach(dev);
608 if (dev->parent)
609 up(&dev->parent->sem);
610 if (ret > 0)
611 ret = 0;
613 return ret < 0 ? ret : 0;
617 * bus_rescan_devices - rescan devices on the bus for possible drivers
618 * @bus: the bus to scan.
620 * This function will look for devices on the bus with no driver
621 * attached and rescan it against existing drivers to see if it matches
622 * any by calling device_attach() for the unbound devices.
624 int bus_rescan_devices(struct bus_type * bus)
626 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
630 * device_reprobe - remove driver for a device and probe for a new driver
631 * @dev: the device to reprobe
633 * This function detaches the attached driver (if any) for the given
634 * device and restarts the driver probing process. It is intended
635 * to use if probing criteria changed during a devices lifetime and
636 * driver attachment should change accordingly.
638 int device_reprobe(struct device *dev)
640 if (dev->driver) {
641 if (dev->parent) /* Needed for USB */
642 down(&dev->parent->sem);
643 device_release_driver(dev);
644 if (dev->parent)
645 up(&dev->parent->sem);
647 return bus_rescan_devices_helper(dev, NULL);
649 EXPORT_SYMBOL_GPL(device_reprobe);
651 struct bus_type *get_bus(struct bus_type *bus)
653 return bus ? container_of(subsys_get(&bus->subsys),
654 struct bus_type, subsys) : NULL;
657 void put_bus(struct bus_type * bus)
659 subsys_put(&bus->subsys);
664 * find_bus - locate bus by name.
665 * @name: name of bus.
667 * Call kset_find_obj() to iterate over list of buses to
668 * find a bus by name. Return bus if found.
670 * Note that kset_find_obj increments bus' reference count.
672 struct bus_type * find_bus(char * name)
674 struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
675 return k ? to_bus(k) : NULL;
680 * bus_add_attrs - Add default attributes for this bus.
681 * @bus: Bus that has just been registered.
684 static int bus_add_attrs(struct bus_type * bus)
686 int error = 0;
687 int i;
689 if (bus->bus_attrs) {
690 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
691 if ((error = bus_create_file(bus,&bus->bus_attrs[i])))
692 goto Err;
695 Done:
696 return error;
697 Err:
698 while (--i >= 0)
699 bus_remove_file(bus,&bus->bus_attrs[i]);
700 goto Done;
703 static void bus_remove_attrs(struct bus_type * bus)
705 int i;
707 if (bus->bus_attrs) {
708 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
709 bus_remove_file(bus,&bus->bus_attrs[i]);
713 static void klist_devices_get(struct klist_node *n)
715 struct device *dev = container_of(n, struct device, knode_bus);
717 get_device(dev);
720 static void klist_devices_put(struct klist_node *n)
722 struct device *dev = container_of(n, struct device, knode_bus);
724 put_device(dev);
728 * bus_register - register a bus with the system.
729 * @bus: bus.
731 * Once we have that, we registered the bus with the kobject
732 * infrastructure, then register the children subsystems it has:
733 * the devices and drivers that belong to the bus.
735 int bus_register(struct bus_type * bus)
737 int retval;
739 BLOCKING_INIT_NOTIFIER_HEAD(&bus->bus_notifier);
741 retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name);
742 if (retval)
743 goto out;
745 subsys_set_kset(bus, bus_subsys);
746 retval = subsystem_register(&bus->subsys);
747 if (retval)
748 goto out;
750 kobject_set_name(&bus->devices.kobj, "devices");
751 bus->devices.subsys = &bus->subsys;
752 retval = kset_register(&bus->devices);
753 if (retval)
754 goto bus_devices_fail;
756 kobject_set_name(&bus->drivers.kobj, "drivers");
757 bus->drivers.subsys = &bus->subsys;
758 bus->drivers.ktype = &ktype_driver;
759 retval = kset_register(&bus->drivers);
760 if (retval)
761 goto bus_drivers_fail;
763 klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
764 klist_init(&bus->klist_drivers, NULL, NULL);
765 retval = bus_add_attrs(bus);
766 if (retval)
767 goto bus_attrs_fail;
769 pr_debug("bus type '%s' registered\n", bus->name);
770 return 0;
772 bus_attrs_fail:
773 kset_unregister(&bus->drivers);
774 bus_drivers_fail:
775 kset_unregister(&bus->devices);
776 bus_devices_fail:
777 subsystem_unregister(&bus->subsys);
778 out:
779 return retval;
784 * bus_unregister - remove a bus from the system
785 * @bus: bus.
787 * Unregister the child subsystems and the bus itself.
788 * Finally, we call put_bus() to release the refcount
790 void bus_unregister(struct bus_type * bus)
792 pr_debug("bus %s: unregistering\n", bus->name);
793 bus_remove_attrs(bus);
794 kset_unregister(&bus->drivers);
795 kset_unregister(&bus->devices);
796 subsystem_unregister(&bus->subsys);
799 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
801 return blocking_notifier_chain_register(&bus->bus_notifier, nb);
803 EXPORT_SYMBOL_GPL(bus_register_notifier);
805 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
807 return blocking_notifier_chain_unregister(&bus->bus_notifier, nb);
809 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
811 int __init buses_init(void)
813 return subsystem_register(&bus_subsys);
817 EXPORT_SYMBOL_GPL(bus_for_each_dev);
818 EXPORT_SYMBOL_GPL(bus_find_device);
819 EXPORT_SYMBOL_GPL(bus_for_each_drv);
821 EXPORT_SYMBOL_GPL(bus_register);
822 EXPORT_SYMBOL_GPL(bus_unregister);
823 EXPORT_SYMBOL_GPL(bus_rescan_devices);
825 EXPORT_SYMBOL_GPL(bus_create_file);
826 EXPORT_SYMBOL_GPL(bus_remove_file);