Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/upstream-linus
[linux-btrfs-devel.git] / drivers / base / bus.c
blob000e7b2006f8f5dc96c269ac3615b8b4668bbd0d
1 /*
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/slab.h>
17 #include <linux/init.h>
18 #include <linux/string.h>
19 #include "base.h"
20 #include "power/power.h"
22 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
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,
32 void *data);
34 static struct bus_type *bus_get(struct bus_type *bus)
36 if (bus) {
37 kset_get(&bus->p->subsys);
38 return bus;
40 return NULL;
43 static void bus_put(struct bus_type *bus)
45 if (bus)
46 kset_put(&bus->p->subsys);
49 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
50 char *buf)
52 struct driver_attribute *drv_attr = to_drv_attr(attr);
53 struct driver_private *drv_priv = to_driver(kobj);
54 ssize_t ret = -EIO;
56 if (drv_attr->show)
57 ret = drv_attr->show(drv_priv->driver, buf);
58 return ret;
61 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
62 const char *buf, size_t count)
64 struct driver_attribute *drv_attr = to_drv_attr(attr);
65 struct driver_private *drv_priv = to_driver(kobj);
66 ssize_t ret = -EIO;
68 if (drv_attr->store)
69 ret = drv_attr->store(drv_priv->driver, buf, count);
70 return ret;
73 static const struct sysfs_ops driver_sysfs_ops = {
74 .show = drv_attr_show,
75 .store = drv_attr_store,
78 static void driver_release(struct kobject *kobj)
80 struct driver_private *drv_priv = to_driver(kobj);
82 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
83 kfree(drv_priv);
86 static struct kobj_type driver_ktype = {
87 .sysfs_ops = &driver_sysfs_ops,
88 .release = driver_release,
92 * sysfs bindings for buses
94 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
95 char *buf)
97 struct bus_attribute *bus_attr = to_bus_attr(attr);
98 struct subsys_private *subsys_priv = to_subsys_private(kobj);
99 ssize_t ret = 0;
101 if (bus_attr->show)
102 ret = bus_attr->show(subsys_priv->bus, buf);
103 return ret;
106 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
107 const char *buf, size_t count)
109 struct bus_attribute *bus_attr = to_bus_attr(attr);
110 struct subsys_private *subsys_priv = to_subsys_private(kobj);
111 ssize_t ret = 0;
113 if (bus_attr->store)
114 ret = bus_attr->store(subsys_priv->bus, buf, count);
115 return ret;
118 static const struct sysfs_ops bus_sysfs_ops = {
119 .show = bus_attr_show,
120 .store = bus_attr_store,
123 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
125 int error;
126 if (bus_get(bus)) {
127 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
128 bus_put(bus);
129 } else
130 error = -EINVAL;
131 return error;
133 EXPORT_SYMBOL_GPL(bus_create_file);
135 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
137 if (bus_get(bus)) {
138 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
139 bus_put(bus);
142 EXPORT_SYMBOL_GPL(bus_remove_file);
144 static struct kobj_type bus_ktype = {
145 .sysfs_ops = &bus_sysfs_ops,
148 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
150 struct kobj_type *ktype = get_ktype(kobj);
152 if (ktype == &bus_ktype)
153 return 1;
154 return 0;
157 static const struct kset_uevent_ops bus_uevent_ops = {
158 .filter = bus_uevent_filter,
161 static struct kset *bus_kset;
164 #ifdef CONFIG_HOTPLUG
165 /* Manually detach a device from its associated driver. */
166 static ssize_t driver_unbind(struct device_driver *drv,
167 const char *buf, size_t count)
169 struct bus_type *bus = bus_get(drv->bus);
170 struct device *dev;
171 int err = -ENODEV;
173 dev = bus_find_device_by_name(bus, NULL, buf);
174 if (dev && dev->driver == drv) {
175 if (dev->parent) /* Needed for USB */
176 device_lock(dev->parent);
177 device_release_driver(dev);
178 if (dev->parent)
179 device_unlock(dev->parent);
180 err = count;
182 put_device(dev);
183 bus_put(bus);
184 return err;
186 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
189 * Manually attach a device to a driver.
190 * Note: the driver must want to bind to the device,
191 * it is not possible to override the driver's id table.
193 static ssize_t driver_bind(struct device_driver *drv,
194 const char *buf, size_t count)
196 struct bus_type *bus = bus_get(drv->bus);
197 struct device *dev;
198 int err = -ENODEV;
200 dev = bus_find_device_by_name(bus, NULL, buf);
201 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
202 if (dev->parent) /* Needed for USB */
203 device_lock(dev->parent);
204 device_lock(dev);
205 err = driver_probe_device(drv, dev);
206 device_unlock(dev);
207 if (dev->parent)
208 device_unlock(dev->parent);
210 if (err > 0) {
211 /* success */
212 err = count;
213 } else if (err == 0) {
214 /* driver didn't accept device */
215 err = -ENODEV;
218 put_device(dev);
219 bus_put(bus);
220 return err;
222 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
224 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
226 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
229 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
230 const char *buf, size_t count)
232 if (buf[0] == '0')
233 bus->p->drivers_autoprobe = 0;
234 else
235 bus->p->drivers_autoprobe = 1;
236 return count;
239 static ssize_t store_drivers_probe(struct bus_type *bus,
240 const char *buf, size_t count)
242 struct device *dev;
244 dev = bus_find_device_by_name(bus, NULL, buf);
245 if (!dev)
246 return -ENODEV;
247 if (bus_rescan_devices_helper(dev, NULL) != 0)
248 return -EINVAL;
249 return count;
251 #endif
253 static struct device *next_device(struct klist_iter *i)
255 struct klist_node *n = klist_next(i);
256 struct device *dev = NULL;
257 struct device_private *dev_prv;
259 if (n) {
260 dev_prv = to_device_private_bus(n);
261 dev = dev_prv->device;
263 return dev;
267 * bus_for_each_dev - device iterator.
268 * @bus: bus type.
269 * @start: device to start iterating from.
270 * @data: data for the callback.
271 * @fn: function to be called for each device.
273 * Iterate over @bus's list of devices, and call @fn for each,
274 * passing it @data. If @start is not NULL, we use that device to
275 * begin iterating from.
277 * We check the return of @fn each time. If it returns anything
278 * other than 0, we break out and return that value.
280 * NOTE: The device that returns a non-zero value is not retained
281 * in any way, nor is its refcount incremented. If the caller needs
282 * to retain this data, it should do so, and increment the reference
283 * count in the supplied callback.
285 int bus_for_each_dev(struct bus_type *bus, struct device *start,
286 void *data, int (*fn)(struct device *, void *))
288 struct klist_iter i;
289 struct device *dev;
290 int error = 0;
292 if (!bus)
293 return -EINVAL;
295 klist_iter_init_node(&bus->p->klist_devices, &i,
296 (start ? &start->p->knode_bus : NULL));
297 while ((dev = next_device(&i)) && !error)
298 error = fn(dev, data);
299 klist_iter_exit(&i);
300 return error;
302 EXPORT_SYMBOL_GPL(bus_for_each_dev);
305 * bus_find_device - device iterator for locating a particular device.
306 * @bus: bus type
307 * @start: Device to begin with
308 * @data: Data to pass to match function
309 * @match: Callback function to check device
311 * This is similar to the bus_for_each_dev() function above, but it
312 * returns a reference to a device that is 'found' for later use, as
313 * determined by the @match callback.
315 * The callback should return 0 if the device doesn't match and non-zero
316 * if it does. If the callback returns non-zero, this function will
317 * return to the caller and not iterate over any more devices.
319 struct device *bus_find_device(struct bus_type *bus,
320 struct device *start, void *data,
321 int (*match)(struct device *dev, void *data))
323 struct klist_iter i;
324 struct device *dev;
326 if (!bus)
327 return NULL;
329 klist_iter_init_node(&bus->p->klist_devices, &i,
330 (start ? &start->p->knode_bus : NULL));
331 while ((dev = next_device(&i)))
332 if (match(dev, data) && get_device(dev))
333 break;
334 klist_iter_exit(&i);
335 return dev;
337 EXPORT_SYMBOL_GPL(bus_find_device);
339 static int match_name(struct device *dev, void *data)
341 const char *name = data;
343 return sysfs_streq(name, dev_name(dev));
347 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
348 * @bus: bus type
349 * @start: Device to begin with
350 * @name: name of the device to match
352 * This is similar to the bus_find_device() function above, but it handles
353 * searching by a name automatically, no need to write another strcmp matching
354 * function.
356 struct device *bus_find_device_by_name(struct bus_type *bus,
357 struct device *start, const char *name)
359 return bus_find_device(bus, start, (void *)name, match_name);
361 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
363 static struct device_driver *next_driver(struct klist_iter *i)
365 struct klist_node *n = klist_next(i);
366 struct driver_private *drv_priv;
368 if (n) {
369 drv_priv = container_of(n, struct driver_private, knode_bus);
370 return drv_priv->driver;
372 return NULL;
376 * bus_for_each_drv - driver iterator
377 * @bus: bus we're dealing with.
378 * @start: driver to start iterating on.
379 * @data: data to pass to the callback.
380 * @fn: function to call for each driver.
382 * This is nearly identical to the device iterator above.
383 * We iterate over each driver that belongs to @bus, and call
384 * @fn for each. If @fn returns anything but 0, we break out
385 * and return it. If @start is not NULL, we use it as the head
386 * of the list.
388 * NOTE: we don't return the driver that returns a non-zero
389 * value, nor do we leave the reference count incremented for that
390 * driver. If the caller needs to know that info, it must set it
391 * in the callback. It must also be sure to increment the refcount
392 * so it doesn't disappear before returning to the caller.
394 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
395 void *data, int (*fn)(struct device_driver *, void *))
397 struct klist_iter i;
398 struct device_driver *drv;
399 int error = 0;
401 if (!bus)
402 return -EINVAL;
404 klist_iter_init_node(&bus->p->klist_drivers, &i,
405 start ? &start->p->knode_bus : NULL);
406 while ((drv = next_driver(&i)) && !error)
407 error = fn(drv, data);
408 klist_iter_exit(&i);
409 return error;
411 EXPORT_SYMBOL_GPL(bus_for_each_drv);
413 static int device_add_attrs(struct bus_type *bus, struct device *dev)
415 int error = 0;
416 int i;
418 if (!bus->dev_attrs)
419 return 0;
421 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
422 error = device_create_file(dev, &bus->dev_attrs[i]);
423 if (error) {
424 while (--i >= 0)
425 device_remove_file(dev, &bus->dev_attrs[i]);
426 break;
429 return error;
432 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
434 int i;
436 if (bus->dev_attrs) {
437 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
438 device_remove_file(dev, &bus->dev_attrs[i]);
443 * bus_add_device - add device to bus
444 * @dev: device being added
446 * - Add device's bus attributes.
447 * - Create links to device's bus.
448 * - Add the device to its bus's list of devices.
450 int bus_add_device(struct device *dev)
452 struct bus_type *bus = bus_get(dev->bus);
453 int error = 0;
455 if (bus) {
456 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
457 error = device_add_attrs(bus, dev);
458 if (error)
459 goto out_put;
460 error = sysfs_create_link(&bus->p->devices_kset->kobj,
461 &dev->kobj, dev_name(dev));
462 if (error)
463 goto out_id;
464 error = sysfs_create_link(&dev->kobj,
465 &dev->bus->p->subsys.kobj, "subsystem");
466 if (error)
467 goto out_subsys;
468 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
470 return 0;
472 out_subsys:
473 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
474 out_id:
475 device_remove_attrs(bus, dev);
476 out_put:
477 bus_put(dev->bus);
478 return error;
482 * bus_probe_device - probe drivers for a new device
483 * @dev: device to probe
485 * - Automatically probe for a driver if the bus allows it.
487 void bus_probe_device(struct device *dev)
489 struct bus_type *bus = dev->bus;
490 int ret;
492 if (bus && bus->p->drivers_autoprobe) {
493 ret = device_attach(dev);
494 WARN_ON(ret < 0);
499 * bus_remove_device - remove device from bus
500 * @dev: device to be removed
502 * - Remove symlink from bus's directory.
503 * - Delete device from bus's list.
504 * - Detach from its driver.
505 * - Drop reference taken in bus_add_device().
507 void bus_remove_device(struct device *dev)
509 if (dev->bus) {
510 sysfs_remove_link(&dev->kobj, "subsystem");
511 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
512 dev_name(dev));
513 device_remove_attrs(dev->bus, dev);
514 if (klist_node_attached(&dev->p->knode_bus))
515 klist_del(&dev->p->knode_bus);
517 pr_debug("bus: '%s': remove device %s\n",
518 dev->bus->name, dev_name(dev));
519 device_release_driver(dev);
520 bus_put(dev->bus);
524 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
526 int error = 0;
527 int i;
529 if (bus->drv_attrs) {
530 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
531 error = driver_create_file(drv, &bus->drv_attrs[i]);
532 if (error)
533 goto err;
536 done:
537 return error;
538 err:
539 while (--i >= 0)
540 driver_remove_file(drv, &bus->drv_attrs[i]);
541 goto done;
544 static void driver_remove_attrs(struct bus_type *bus,
545 struct device_driver *drv)
547 int i;
549 if (bus->drv_attrs) {
550 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
551 driver_remove_file(drv, &bus->drv_attrs[i]);
555 #ifdef CONFIG_HOTPLUG
557 * Thanks to drivers making their tables __devinit, we can't allow manual
558 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
560 static int __must_check add_bind_files(struct device_driver *drv)
562 int ret;
564 ret = driver_create_file(drv, &driver_attr_unbind);
565 if (ret == 0) {
566 ret = driver_create_file(drv, &driver_attr_bind);
567 if (ret)
568 driver_remove_file(drv, &driver_attr_unbind);
570 return ret;
573 static void remove_bind_files(struct device_driver *drv)
575 driver_remove_file(drv, &driver_attr_bind);
576 driver_remove_file(drv, &driver_attr_unbind);
579 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
580 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
581 show_drivers_autoprobe, store_drivers_autoprobe);
583 static int add_probe_files(struct bus_type *bus)
585 int retval;
587 retval = bus_create_file(bus, &bus_attr_drivers_probe);
588 if (retval)
589 goto out;
591 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
592 if (retval)
593 bus_remove_file(bus, &bus_attr_drivers_probe);
594 out:
595 return retval;
598 static void remove_probe_files(struct bus_type *bus)
600 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
601 bus_remove_file(bus, &bus_attr_drivers_probe);
603 #else
604 static inline int add_bind_files(struct device_driver *drv) { return 0; }
605 static inline void remove_bind_files(struct device_driver *drv) {}
606 static inline int add_probe_files(struct bus_type *bus) { return 0; }
607 static inline void remove_probe_files(struct bus_type *bus) {}
608 #endif
610 static ssize_t driver_uevent_store(struct device_driver *drv,
611 const char *buf, size_t count)
613 enum kobject_action action;
615 if (kobject_action_type(buf, count, &action) == 0)
616 kobject_uevent(&drv->p->kobj, action);
617 return count;
619 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
622 * bus_add_driver - Add a driver to the bus.
623 * @drv: driver.
625 int bus_add_driver(struct device_driver *drv)
627 struct bus_type *bus;
628 struct driver_private *priv;
629 int error = 0;
631 bus = bus_get(drv->bus);
632 if (!bus)
633 return -EINVAL;
635 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
637 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
638 if (!priv) {
639 error = -ENOMEM;
640 goto out_put_bus;
642 klist_init(&priv->klist_devices, NULL, NULL);
643 priv->driver = drv;
644 drv->p = priv;
645 priv->kobj.kset = bus->p->drivers_kset;
646 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
647 "%s", drv->name);
648 if (error)
649 goto out_unregister;
651 if (drv->bus->p->drivers_autoprobe) {
652 error = driver_attach(drv);
653 if (error)
654 goto out_unregister;
656 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
657 module_add_driver(drv->owner, drv);
659 error = driver_create_file(drv, &driver_attr_uevent);
660 if (error) {
661 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
662 __func__, drv->name);
664 error = driver_add_attrs(bus, drv);
665 if (error) {
666 /* How the hell do we get out of this pickle? Give up */
667 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
668 __func__, drv->name);
671 if (!drv->suppress_bind_attrs) {
672 error = add_bind_files(drv);
673 if (error) {
674 /* Ditto */
675 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
676 __func__, drv->name);
680 kobject_uevent(&priv->kobj, KOBJ_ADD);
681 return 0;
683 out_unregister:
684 kobject_put(&priv->kobj);
685 kfree(drv->p);
686 drv->p = NULL;
687 out_put_bus:
688 bus_put(bus);
689 return error;
693 * bus_remove_driver - delete driver from bus's knowledge.
694 * @drv: driver.
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().
700 void bus_remove_driver(struct device_driver *drv)
702 if (!drv->bus)
703 return;
705 if (!drv->suppress_bind_attrs)
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);
711 driver_detach(drv);
712 module_remove_driver(drv);
713 kobject_put(&drv->p->kobj);
714 bus_put(drv->bus);
717 /* Helper for bus_rescan_devices's iter */
718 static int __must_check bus_rescan_devices_helper(struct device *dev,
719 void *data)
721 int ret = 0;
723 if (!dev->driver) {
724 if (dev->parent) /* Needed for USB */
725 device_lock(dev->parent);
726 ret = device_attach(dev);
727 if (dev->parent)
728 device_unlock(dev->parent);
730 return ret < 0 ? ret : 0;
734 * bus_rescan_devices - rescan devices on the bus for possible drivers
735 * @bus: the bus to scan.
737 * This function will look for devices on the bus with no driver
738 * attached and rescan it against existing drivers to see if it matches
739 * any by calling device_attach() for the unbound devices.
741 int bus_rescan_devices(struct bus_type *bus)
743 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
745 EXPORT_SYMBOL_GPL(bus_rescan_devices);
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)
758 if (dev->driver) {
759 if (dev->parent) /* Needed for USB */
760 device_lock(dev->parent);
761 device_release_driver(dev);
762 if (dev->parent)
763 device_unlock(dev->parent);
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.
778 #if 0
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;
784 #endif /* 0 */
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)
794 int error = 0;
795 int i;
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]);
800 if (error)
801 goto err;
804 done:
805 return error;
806 err:
807 while (--i >= 0)
808 bus_remove_file(bus, &bus->bus_attrs[i]);
809 goto done;
812 static void bus_remove_attrs(struct bus_type *bus)
814 int i;
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_private *dev_prv = to_device_private_bus(n);
825 struct device *dev = dev_prv->device;
827 get_device(dev);
830 static void klist_devices_put(struct klist_node *n)
832 struct device_private *dev_prv = to_device_private_bus(n);
833 struct device *dev = dev_prv->device;
835 put_device(dev);
838 static ssize_t bus_uevent_store(struct bus_type *bus,
839 const char *buf, size_t count)
841 enum kobject_action action;
843 if (kobject_action_type(buf, count, &action) == 0)
844 kobject_uevent(&bus->p->subsys.kobj, action);
845 return count;
847 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
850 * bus_register - register a bus with the system.
851 * @bus: bus.
853 * Once we have that, we registered the bus with the kobject
854 * infrastructure, then register the children subsystems it has:
855 * the devices and drivers that belong to the bus.
857 int bus_register(struct bus_type *bus)
859 int retval;
860 struct subsys_private *priv;
862 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
863 if (!priv)
864 return -ENOMEM;
866 priv->bus = bus;
867 bus->p = priv;
869 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
871 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
872 if (retval)
873 goto out;
875 priv->subsys.kobj.kset = bus_kset;
876 priv->subsys.kobj.ktype = &bus_ktype;
877 priv->drivers_autoprobe = 1;
879 retval = kset_register(&priv->subsys);
880 if (retval)
881 goto out;
883 retval = bus_create_file(bus, &bus_attr_uevent);
884 if (retval)
885 goto bus_uevent_fail;
887 priv->devices_kset = kset_create_and_add("devices", NULL,
888 &priv->subsys.kobj);
889 if (!priv->devices_kset) {
890 retval = -ENOMEM;
891 goto bus_devices_fail;
894 priv->drivers_kset = kset_create_and_add("drivers", NULL,
895 &priv->subsys.kobj);
896 if (!priv->drivers_kset) {
897 retval = -ENOMEM;
898 goto bus_drivers_fail;
901 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
902 klist_init(&priv->klist_drivers, NULL, NULL);
904 retval = add_probe_files(bus);
905 if (retval)
906 goto bus_probe_files_fail;
908 retval = bus_add_attrs(bus);
909 if (retval)
910 goto bus_attrs_fail;
912 pr_debug("bus: '%s': registered\n", bus->name);
913 return 0;
915 bus_attrs_fail:
916 remove_probe_files(bus);
917 bus_probe_files_fail:
918 kset_unregister(bus->p->drivers_kset);
919 bus_drivers_fail:
920 kset_unregister(bus->p->devices_kset);
921 bus_devices_fail:
922 bus_remove_file(bus, &bus_attr_uevent);
923 bus_uevent_fail:
924 kset_unregister(&bus->p->subsys);
925 out:
926 kfree(bus->p);
927 bus->p = NULL;
928 return retval;
930 EXPORT_SYMBOL_GPL(bus_register);
933 * bus_unregister - remove a bus from the system
934 * @bus: bus.
936 * Unregister the child subsystems and the bus itself.
937 * Finally, we call bus_put() to release the refcount
939 void bus_unregister(struct bus_type *bus)
941 pr_debug("bus: '%s': unregistering\n", bus->name);
942 bus_remove_attrs(bus);
943 remove_probe_files(bus);
944 kset_unregister(bus->p->drivers_kset);
945 kset_unregister(bus->p->devices_kset);
946 bus_remove_file(bus, &bus_attr_uevent);
947 kset_unregister(&bus->p->subsys);
948 kfree(bus->p);
949 bus->p = NULL;
951 EXPORT_SYMBOL_GPL(bus_unregister);
953 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
955 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
957 EXPORT_SYMBOL_GPL(bus_register_notifier);
959 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
961 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
963 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
965 struct kset *bus_get_kset(struct bus_type *bus)
967 return &bus->p->subsys;
969 EXPORT_SYMBOL_GPL(bus_get_kset);
971 struct klist *bus_get_device_klist(struct bus_type *bus)
973 return &bus->p->klist_devices;
975 EXPORT_SYMBOL_GPL(bus_get_device_klist);
978 * Yes, this forcibly breaks the klist abstraction temporarily. It
979 * just wants to sort the klist, not change reference counts and
980 * take/drop locks rapidly in the process. It does all this while
981 * holding the lock for the list, so objects can't otherwise be
982 * added/removed while we're swizzling.
984 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
985 int (*compare)(const struct device *a,
986 const struct device *b))
988 struct list_head *pos;
989 struct klist_node *n;
990 struct device_private *dev_prv;
991 struct device *b;
993 list_for_each(pos, list) {
994 n = container_of(pos, struct klist_node, n_node);
995 dev_prv = to_device_private_bus(n);
996 b = dev_prv->device;
997 if (compare(a, b) <= 0) {
998 list_move_tail(&a->p->knode_bus.n_node,
999 &b->p->knode_bus.n_node);
1000 return;
1003 list_move_tail(&a->p->knode_bus.n_node, list);
1006 void bus_sort_breadthfirst(struct bus_type *bus,
1007 int (*compare)(const struct device *a,
1008 const struct device *b))
1010 LIST_HEAD(sorted_devices);
1011 struct list_head *pos, *tmp;
1012 struct klist_node *n;
1013 struct device_private *dev_prv;
1014 struct device *dev;
1015 struct klist *device_klist;
1017 device_klist = bus_get_device_klist(bus);
1019 spin_lock(&device_klist->k_lock);
1020 list_for_each_safe(pos, tmp, &device_klist->k_list) {
1021 n = container_of(pos, struct klist_node, n_node);
1022 dev_prv = to_device_private_bus(n);
1023 dev = dev_prv->device;
1024 device_insertion_sort_klist(dev, &sorted_devices, compare);
1026 list_splice(&sorted_devices, &device_klist->k_list);
1027 spin_unlock(&device_klist->k_lock);
1029 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1031 int __init buses_init(void)
1033 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1034 if (!bus_kset)
1035 return -ENOMEM;
1036 return 0;