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1/*
2 * bus.c - bus driver management
3 *
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.
8 *
9 * This file is released under the GPLv2
10 *
11 */
12
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 <linux/mutex.h>
20#include <linux/sysfs.h>
21#include "base.h"
22#include "power/power.h"
23
24/* /sys/devices/system */
25static struct kset *system_kset;
26
27#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
28
29/*
30 * sysfs bindings for drivers
31 */
32
33#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
34
35
36static int __must_check bus_rescan_devices_helper(struct device *dev,
37 void *data);
38
39static struct bus_type *bus_get(struct bus_type *bus)
40{
41 if (bus) {
42 kset_get(&bus->p->subsys);
43 return bus;
44 }
45 return NULL;
46}
47
48static void bus_put(struct bus_type *bus)
49{
50 if (bus)
51 kset_put(&bus->p->subsys);
52}
53
54static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
55 char *buf)
56{
57 struct driver_attribute *drv_attr = to_drv_attr(attr);
58 struct driver_private *drv_priv = to_driver(kobj);
59 ssize_t ret = -EIO;
60
61 if (drv_attr->show)
62 ret = drv_attr->show(drv_priv->driver, buf);
63 return ret;
64}
65
66static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
67 const char *buf, size_t count)
68{
69 struct driver_attribute *drv_attr = to_drv_attr(attr);
70 struct driver_private *drv_priv = to_driver(kobj);
71 ssize_t ret = -EIO;
72
73 if (drv_attr->store)
74 ret = drv_attr->store(drv_priv->driver, buf, count);
75 return ret;
76}
77
78static const struct sysfs_ops driver_sysfs_ops = {
79 .show = drv_attr_show,
80 .store = drv_attr_store,
81};
82
83static void driver_release(struct kobject *kobj)
84{
85 struct driver_private *drv_priv = to_driver(kobj);
86
87 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
88 kfree(drv_priv);
89}
90
91static struct kobj_type driver_ktype = {
92 .sysfs_ops = &driver_sysfs_ops,
93 .release = driver_release,
94};
95
96/*
97 * sysfs bindings for buses
98 */
99static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
100 char *buf)
101{
102 struct bus_attribute *bus_attr = to_bus_attr(attr);
103 struct subsys_private *subsys_priv = to_subsys_private(kobj);
104 ssize_t ret = 0;
105
106 if (bus_attr->show)
107 ret = bus_attr->show(subsys_priv->bus, buf);
108 return ret;
109}
110
111static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
112 const char *buf, size_t count)
113{
114 struct bus_attribute *bus_attr = to_bus_attr(attr);
115 struct subsys_private *subsys_priv = to_subsys_private(kobj);
116 ssize_t ret = 0;
117
118 if (bus_attr->store)
119 ret = bus_attr->store(subsys_priv->bus, buf, count);
120 return ret;
121}
122
123static const struct sysfs_ops bus_sysfs_ops = {
124 .show = bus_attr_show,
125 .store = bus_attr_store,
126};
127
128int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
129{
130 int error;
131 if (bus_get(bus)) {
132 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
133 bus_put(bus);
134 } else
135 error = -EINVAL;
136 return error;
137}
138EXPORT_SYMBOL_GPL(bus_create_file);
139
140void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
141{
142 if (bus_get(bus)) {
143 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
144 bus_put(bus);
145 }
146}
147EXPORT_SYMBOL_GPL(bus_remove_file);
148
149static void bus_release(struct kobject *kobj)
150{
151 struct subsys_private *priv =
152 container_of(kobj, typeof(*priv), subsys.kobj);
153 struct bus_type *bus = priv->bus;
154
155 kfree(priv);
156 bus->p = NULL;
157}
158
159static struct kobj_type bus_ktype = {
160 .sysfs_ops = &bus_sysfs_ops,
161 .release = bus_release,
162};
163
164static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
165{
166 struct kobj_type *ktype = get_ktype(kobj);
167
168 if (ktype == &bus_ktype)
169 return 1;
170 return 0;
171}
172
173static const struct kset_uevent_ops bus_uevent_ops = {
174 .filter = bus_uevent_filter,
175};
176
177static struct kset *bus_kset;
178
179/* Manually detach a device from its associated driver. */
180static ssize_t unbind_store(struct device_driver *drv, const char *buf,
181 size_t count)
182{
183 struct bus_type *bus = bus_get(drv->bus);
184 struct device *dev;
185 int err = -ENODEV;
186
187 dev = bus_find_device_by_name(bus, NULL, buf);
188 if (dev && dev->driver == drv) {
189 if (dev->parent) /* Needed for USB */
190 device_lock(dev->parent);
191 device_release_driver(dev);
192 if (dev->parent)
193 device_unlock(dev->parent);
194 err = count;
195 }
196 put_device(dev);
197 bus_put(bus);
198 return err;
199}
200static DRIVER_ATTR_WO(unbind);
201
202/*
203 * Manually attach a device to a driver.
204 * Note: the driver must want to bind to the device,
205 * it is not possible to override the driver's id table.
206 */
207static ssize_t bind_store(struct device_driver *drv, const char *buf,
208 size_t count)
209{
210 struct bus_type *bus = bus_get(drv->bus);
211 struct device *dev;
212 int err = -ENODEV;
213
214 dev = bus_find_device_by_name(bus, NULL, buf);
215 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
216 if (dev->parent) /* Needed for USB */
217 device_lock(dev->parent);
218 device_lock(dev);
219 err = driver_probe_device(drv, dev);
220 device_unlock(dev);
221 if (dev->parent)
222 device_unlock(dev->parent);
223
224 if (err > 0) {
225 /* success */
226 err = count;
227 } else if (err == 0) {
228 /* driver didn't accept device */
229 err = -ENODEV;
230 }
231 }
232 put_device(dev);
233 bus_put(bus);
234 return err;
235}
236static DRIVER_ATTR_WO(bind);
237
238static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
239{
240 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
241}
242
243static ssize_t store_drivers_autoprobe(struct bus_type *bus,
244 const char *buf, size_t count)
245{
246 if (buf[0] == '0')
247 bus->p->drivers_autoprobe = 0;
248 else
249 bus->p->drivers_autoprobe = 1;
250 return count;
251}
252
253static ssize_t store_drivers_probe(struct bus_type *bus,
254 const char *buf, size_t count)
255{
256 struct device *dev;
257
258 dev = bus_find_device_by_name(bus, NULL, buf);
259 if (!dev)
260 return -ENODEV;
261 if (bus_rescan_devices_helper(dev, NULL) != 0)
262 return -EINVAL;
263 return count;
264}
265
266static struct device *next_device(struct klist_iter *i)
267{
268 struct klist_node *n = klist_next(i);
269 struct device *dev = NULL;
270 struct device_private *dev_prv;
271
272 if (n) {
273 dev_prv = to_device_private_bus(n);
274 dev = dev_prv->device;
275 }
276 return dev;
277}
278
279/**
280 * bus_for_each_dev - device iterator.
281 * @bus: bus type.
282 * @start: device to start iterating from.
283 * @data: data for the callback.
284 * @fn: function to be called for each device.
285 *
286 * Iterate over @bus's list of devices, and call @fn for each,
287 * passing it @data. If @start is not NULL, we use that device to
288 * begin iterating from.
289 *
290 * We check the return of @fn each time. If it returns anything
291 * other than 0, we break out and return that value.
292 *
293 * NOTE: The device that returns a non-zero value is not retained
294 * in any way, nor is its refcount incremented. If the caller needs
295 * to retain this data, it should do so, and increment the reference
296 * count in the supplied callback.
297 */
298int bus_for_each_dev(struct bus_type *bus, struct device *start,
299 void *data, int (*fn)(struct device *, void *))
300{
301 struct klist_iter i;
302 struct device *dev;
303 int error = 0;
304
305 if (!bus || !bus->p)
306 return -EINVAL;
307
308 klist_iter_init_node(&bus->p->klist_devices, &i,
309 (start ? &start->p->knode_bus : NULL));
310 while ((dev = next_device(&i)) && !error)
311 error = fn(dev, data);
312 klist_iter_exit(&i);
313 return error;
314}
315EXPORT_SYMBOL_GPL(bus_for_each_dev);
316
317/**
318 * bus_find_device - device iterator for locating a particular device.
319 * @bus: bus type
320 * @start: Device to begin with
321 * @data: Data to pass to match function
322 * @match: Callback function to check device
323 *
324 * This is similar to the bus_for_each_dev() function above, but it
325 * returns a reference to a device that is 'found' for later use, as
326 * determined by the @match callback.
327 *
328 * The callback should return 0 if the device doesn't match and non-zero
329 * if it does. If the callback returns non-zero, this function will
330 * return to the caller and not iterate over any more devices.
331 */
332struct device *bus_find_device(struct bus_type *bus,
333 struct device *start, void *data,
334 int (*match)(struct device *dev, void *data))
335{
336 struct klist_iter i;
337 struct device *dev;
338
339 if (!bus || !bus->p)
340 return NULL;
341
342 klist_iter_init_node(&bus->p->klist_devices, &i,
343 (start ? &start->p->knode_bus : NULL));
344 while ((dev = next_device(&i)))
345 if (match(dev, data) && get_device(dev))
346 break;
347 klist_iter_exit(&i);
348 return dev;
349}
350EXPORT_SYMBOL_GPL(bus_find_device);
351
352static int match_name(struct device *dev, void *data)
353{
354 const char *name = data;
355
356 return sysfs_streq(name, dev_name(dev));
357}
358
359/**
360 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
361 * @bus: bus type
362 * @start: Device to begin with
363 * @name: name of the device to match
364 *
365 * This is similar to the bus_find_device() function above, but it handles
366 * searching by a name automatically, no need to write another strcmp matching
367 * function.
368 */
369struct device *bus_find_device_by_name(struct bus_type *bus,
370 struct device *start, const char *name)
371{
372 return bus_find_device(bus, start, (void *)name, match_name);
373}
374EXPORT_SYMBOL_GPL(bus_find_device_by_name);
375
376/**
377 * subsys_find_device_by_id - find a device with a specific enumeration number
378 * @subsys: subsystem
379 * @id: index 'id' in struct device
380 * @hint: device to check first
381 *
382 * Check the hint's next object and if it is a match return it directly,
383 * otherwise, fall back to a full list search. Either way a reference for
384 * the returned object is taken.
385 */
386struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
387 struct device *hint)
388{
389 struct klist_iter i;
390 struct device *dev;
391
392 if (!subsys)
393 return NULL;
394
395 if (hint) {
396 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
397 dev = next_device(&i);
398 if (dev && dev->id == id && get_device(dev)) {
399 klist_iter_exit(&i);
400 return dev;
401 }
402 klist_iter_exit(&i);
403 }
404
405 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
406 while ((dev = next_device(&i))) {
407 if (dev->id == id && get_device(dev)) {
408 klist_iter_exit(&i);
409 return dev;
410 }
411 }
412 klist_iter_exit(&i);
413 return NULL;
414}
415EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
416
417static struct device_driver *next_driver(struct klist_iter *i)
418{
419 struct klist_node *n = klist_next(i);
420 struct driver_private *drv_priv;
421
422 if (n) {
423 drv_priv = container_of(n, struct driver_private, knode_bus);
424 return drv_priv->driver;
425 }
426 return NULL;
427}
428
429/**
430 * bus_for_each_drv - driver iterator
431 * @bus: bus we're dealing with.
432 * @start: driver to start iterating on.
433 * @data: data to pass to the callback.
434 * @fn: function to call for each driver.
435 *
436 * This is nearly identical to the device iterator above.
437 * We iterate over each driver that belongs to @bus, and call
438 * @fn for each. If @fn returns anything but 0, we break out
439 * and return it. If @start is not NULL, we use it as the head
440 * of the list.
441 *
442 * NOTE: we don't return the driver that returns a non-zero
443 * value, nor do we leave the reference count incremented for that
444 * driver. If the caller needs to know that info, it must set it
445 * in the callback. It must also be sure to increment the refcount
446 * so it doesn't disappear before returning to the caller.
447 */
448int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
449 void *data, int (*fn)(struct device_driver *, void *))
450{
451 struct klist_iter i;
452 struct device_driver *drv;
453 int error = 0;
454
455 if (!bus)
456 return -EINVAL;
457
458 klist_iter_init_node(&bus->p->klist_drivers, &i,
459 start ? &start->p->knode_bus : NULL);
460 while ((drv = next_driver(&i)) && !error)
461 error = fn(drv, data);
462 klist_iter_exit(&i);
463 return error;
464}
465EXPORT_SYMBOL_GPL(bus_for_each_drv);
466
467static int device_add_attrs(struct bus_type *bus, struct device *dev)
468{
469 int error = 0;
470 int i;
471
472 if (!bus->dev_attrs)
473 return 0;
474
475 for (i = 0; bus->dev_attrs[i].attr.name; i++) {
476 error = device_create_file(dev, &bus->dev_attrs[i]);
477 if (error) {
478 while (--i >= 0)
479 device_remove_file(dev, &bus->dev_attrs[i]);
480 break;
481 }
482 }
483 return error;
484}
485
486static void device_remove_attrs(struct bus_type *bus, struct device *dev)
487{
488 int i;
489
490 if (bus->dev_attrs) {
491 for (i = 0; bus->dev_attrs[i].attr.name; i++)
492 device_remove_file(dev, &bus->dev_attrs[i]);
493 }
494}
495
496/**
497 * bus_add_device - add device to bus
498 * @dev: device being added
499 *
500 * - Add device's bus attributes.
501 * - Create links to device's bus.
502 * - Add the device to its bus's list of devices.
503 */
504int bus_add_device(struct device *dev)
505{
506 struct bus_type *bus = bus_get(dev->bus);
507 int error = 0;
508
509 if (bus) {
510 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
511 error = device_add_attrs(bus, dev);
512 if (error)
513 goto out_put;
514 error = device_add_groups(dev, bus->dev_groups);
515 if (error)
516 goto out_groups;
517 error = sysfs_create_link(&bus->p->devices_kset->kobj,
518 &dev->kobj, dev_name(dev));
519 if (error)
520 goto out_id;
521 error = sysfs_create_link(&dev->kobj,
522 &dev->bus->p->subsys.kobj, "subsystem");
523 if (error)
524 goto out_subsys;
525 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
526 }
527 return 0;
528
529out_subsys:
530 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
531out_groups:
532 device_remove_groups(dev, bus->dev_groups);
533out_id:
534 device_remove_attrs(bus, dev);
535out_put:
536 bus_put(dev->bus);
537 return error;
538}
539
540/**
541 * bus_probe_device - probe drivers for a new device
542 * @dev: device to probe
543 *
544 * - Automatically probe for a driver if the bus allows it.
545 */
546void bus_probe_device(struct device *dev)
547{
548 struct bus_type *bus = dev->bus;
549 struct subsys_interface *sif;
550 int ret;
551
552 if (!bus)
553 return;
554
555 if (bus->p->drivers_autoprobe) {
556 ret = device_attach(dev);
557 WARN_ON(ret < 0);
558 }
559
560 mutex_lock(&bus->p->mutex);
561 list_for_each_entry(sif, &bus->p->interfaces, node)
562 if (sif->add_dev)
563 sif->add_dev(dev, sif);
564 mutex_unlock(&bus->p->mutex);
565}
566
567/**
568 * bus_remove_device - remove device from bus
569 * @dev: device to be removed
570 *
571 * - Remove device from all interfaces.
572 * - Remove symlink from bus' directory.
573 * - Delete device from bus's list.
574 * - Detach from its driver.
575 * - Drop reference taken in bus_add_device().
576 */
577void bus_remove_device(struct device *dev)
578{
579 struct bus_type *bus = dev->bus;
580 struct subsys_interface *sif;
581
582 if (!bus)
583 return;
584
585 mutex_lock(&bus->p->mutex);
586 list_for_each_entry(sif, &bus->p->interfaces, node)
587 if (sif->remove_dev)
588 sif->remove_dev(dev, sif);
589 mutex_unlock(&bus->p->mutex);
590
591 sysfs_remove_link(&dev->kobj, "subsystem");
592 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
593 dev_name(dev));
594 device_remove_attrs(dev->bus, dev);
595 device_remove_groups(dev, dev->bus->dev_groups);
596 if (klist_node_attached(&dev->p->knode_bus))
597 klist_del(&dev->p->knode_bus);
598
599 pr_debug("bus: '%s': remove device %s\n",
600 dev->bus->name, dev_name(dev));
601 device_release_driver(dev);
602 bus_put(dev->bus);
603}
604
605static int __must_check add_bind_files(struct device_driver *drv)
606{
607 int ret;
608
609 ret = driver_create_file(drv, &driver_attr_unbind);
610 if (ret == 0) {
611 ret = driver_create_file(drv, &driver_attr_bind);
612 if (ret)
613 driver_remove_file(drv, &driver_attr_unbind);
614 }
615 return ret;
616}
617
618static void remove_bind_files(struct device_driver *drv)
619{
620 driver_remove_file(drv, &driver_attr_bind);
621 driver_remove_file(drv, &driver_attr_unbind);
622}
623
624static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
625static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
626 show_drivers_autoprobe, store_drivers_autoprobe);
627
628static int add_probe_files(struct bus_type *bus)
629{
630 int retval;
631
632 retval = bus_create_file(bus, &bus_attr_drivers_probe);
633 if (retval)
634 goto out;
635
636 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
637 if (retval)
638 bus_remove_file(bus, &bus_attr_drivers_probe);
639out:
640 return retval;
641}
642
643static void remove_probe_files(struct bus_type *bus)
644{
645 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
646 bus_remove_file(bus, &bus_attr_drivers_probe);
647}
648
649static ssize_t uevent_store(struct device_driver *drv, const char *buf,
650 size_t count)
651{
652 enum kobject_action action;
653
654 if (kobject_action_type(buf, count, &action) == 0)
655 kobject_uevent(&drv->p->kobj, action);
656 return count;
657}
658static DRIVER_ATTR_WO(uevent);
659
660/**
661 * bus_add_driver - Add a driver to the bus.
662 * @drv: driver.
663 */
664int bus_add_driver(struct device_driver *drv)
665{
666 struct bus_type *bus;
667 struct driver_private *priv;
668 int error = 0;
669
670 bus = bus_get(drv->bus);
671 if (!bus)
672 return -EINVAL;
673
674 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
675
676 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
677 if (!priv) {
678 error = -ENOMEM;
679 goto out_put_bus;
680 }
681 klist_init(&priv->klist_devices, NULL, NULL);
682 priv->driver = drv;
683 drv->p = priv;
684 priv->kobj.kset = bus->p->drivers_kset;
685 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
686 "%s", drv->name);
687 if (error)
688 goto out_unregister;
689
690 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
691 if (drv->bus->p->drivers_autoprobe) {
692 error = driver_attach(drv);
693 if (error)
694 goto out_unregister;
695 }
696 module_add_driver(drv->owner, drv);
697
698 error = driver_create_file(drv, &driver_attr_uevent);
699 if (error) {
700 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
701 __func__, drv->name);
702 }
703 error = driver_add_groups(drv, bus->drv_groups);
704 if (error) {
705 /* How the hell do we get out of this pickle? Give up */
706 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
707 __func__, drv->name);
708 }
709
710 if (!drv->suppress_bind_attrs) {
711 error = add_bind_files(drv);
712 if (error) {
713 /* Ditto */
714 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
715 __func__, drv->name);
716 }
717 }
718
719 return 0;
720
721out_unregister:
722 kobject_put(&priv->kobj);
723 kfree(drv->p);
724 drv->p = NULL;
725out_put_bus:
726 bus_put(bus);
727 return error;
728}
729
730/**
731 * bus_remove_driver - delete driver from bus's knowledge.
732 * @drv: driver.
733 *
734 * Detach the driver from the devices it controls, and remove
735 * it from its bus's list of drivers. Finally, we drop the reference
736 * to the bus we took in bus_add_driver().
737 */
738void bus_remove_driver(struct device_driver *drv)
739{
740 if (!drv->bus)
741 return;
742
743 if (!drv->suppress_bind_attrs)
744 remove_bind_files(drv);
745 driver_remove_groups(drv, drv->bus->drv_groups);
746 driver_remove_file(drv, &driver_attr_uevent);
747 klist_remove(&drv->p->knode_bus);
748 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
749 driver_detach(drv);
750 module_remove_driver(drv);
751 kobject_put(&drv->p->kobj);
752 bus_put(drv->bus);
753}
754
755/* Helper for bus_rescan_devices's iter */
756static int __must_check bus_rescan_devices_helper(struct device *dev,
757 void *data)
758{
759 int ret = 0;
760
761 if (!dev->driver) {
762 if (dev->parent) /* Needed for USB */
763 device_lock(dev->parent);
764 ret = device_attach(dev);
765 if (dev->parent)
766 device_unlock(dev->parent);
767 }
768 return ret < 0 ? ret : 0;
769}
770
771/**
772 * bus_rescan_devices - rescan devices on the bus for possible drivers
773 * @bus: the bus to scan.
774 *
775 * This function will look for devices on the bus with no driver
776 * attached and rescan it against existing drivers to see if it matches
777 * any by calling device_attach() for the unbound devices.
778 */
779int bus_rescan_devices(struct bus_type *bus)
780{
781 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
782}
783EXPORT_SYMBOL_GPL(bus_rescan_devices);
784
785/**
786 * device_reprobe - remove driver for a device and probe for a new driver
787 * @dev: the device to reprobe
788 *
789 * This function detaches the attached driver (if any) for the given
790 * device and restarts the driver probing process. It is intended
791 * to use if probing criteria changed during a devices lifetime and
792 * driver attachment should change accordingly.
793 */
794int device_reprobe(struct device *dev)
795{
796 if (dev->driver) {
797 if (dev->parent) /* Needed for USB */
798 device_lock(dev->parent);
799 device_release_driver(dev);
800 if (dev->parent)
801 device_unlock(dev->parent);
802 }
803 return bus_rescan_devices_helper(dev, NULL);
804}
805EXPORT_SYMBOL_GPL(device_reprobe);
806
807/**
808 * find_bus - locate bus by name.
809 * @name: name of bus.
810 *
811 * Call kset_find_obj() to iterate over list of buses to
812 * find a bus by name. Return bus if found.
813 *
814 * Note that kset_find_obj increments bus' reference count.
815 */
816#if 0
817struct bus_type *find_bus(char *name)
818{
819 struct kobject *k = kset_find_obj(bus_kset, name);
820 return k ? to_bus(k) : NULL;
821}
822#endif /* 0 */
823
824static int bus_add_groups(struct bus_type *bus,
825 const struct attribute_group **groups)
826{
827 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
828}
829
830static void bus_remove_groups(struct bus_type *bus,
831 const struct attribute_group **groups)
832{
833 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
834}
835
836static void klist_devices_get(struct klist_node *n)
837{
838 struct device_private *dev_prv = to_device_private_bus(n);
839 struct device *dev = dev_prv->device;
840
841 get_device(dev);
842}
843
844static void klist_devices_put(struct klist_node *n)
845{
846 struct device_private *dev_prv = to_device_private_bus(n);
847 struct device *dev = dev_prv->device;
848
849 put_device(dev);
850}
851
852static ssize_t bus_uevent_store(struct bus_type *bus,
853 const char *buf, size_t count)
854{
855 enum kobject_action action;
856
857 if (kobject_action_type(buf, count, &action) == 0)
858 kobject_uevent(&bus->p->subsys.kobj, action);
859 return count;
860}
861static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
862
863/**
864 * bus_register - register a driver-core subsystem
865 * @bus: bus to register
866 *
867 * Once we have that, we register the bus with the kobject
868 * infrastructure, then register the children subsystems it has:
869 * the devices and drivers that belong to the subsystem.
870 */
871int bus_register(struct bus_type *bus)
872{
873 int retval;
874 struct subsys_private *priv;
875 struct lock_class_key *key = &bus->lock_key;
876
877 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
878 if (!priv)
879 return -ENOMEM;
880
881 priv->bus = bus;
882 bus->p = priv;
883
884 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
885
886 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
887 if (retval)
888 goto out;
889
890 priv->subsys.kobj.kset = bus_kset;
891 priv->subsys.kobj.ktype = &bus_ktype;
892 priv->drivers_autoprobe = 1;
893
894 retval = kset_register(&priv->subsys);
895 if (retval)
896 goto out;
897
898 retval = bus_create_file(bus, &bus_attr_uevent);
899 if (retval)
900 goto bus_uevent_fail;
901
902 priv->devices_kset = kset_create_and_add("devices", NULL,
903 &priv->subsys.kobj);
904 if (!priv->devices_kset) {
905 retval = -ENOMEM;
906 goto bus_devices_fail;
907 }
908
909 priv->drivers_kset = kset_create_and_add("drivers", NULL,
910 &priv->subsys.kobj);
911 if (!priv->drivers_kset) {
912 retval = -ENOMEM;
913 goto bus_drivers_fail;
914 }
915
916 INIT_LIST_HEAD(&priv->interfaces);
917 __mutex_init(&priv->mutex, "subsys mutex", key);
918 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
919 klist_init(&priv->klist_drivers, NULL, NULL);
920
921 retval = add_probe_files(bus);
922 if (retval)
923 goto bus_probe_files_fail;
924
925 retval = bus_add_groups(bus, bus->bus_groups);
926 if (retval)
927 goto bus_groups_fail;
928
929 pr_debug("bus: '%s': registered\n", bus->name);
930 return 0;
931
932bus_groups_fail:
933 remove_probe_files(bus);
934bus_probe_files_fail:
935 kset_unregister(bus->p->drivers_kset);
936bus_drivers_fail:
937 kset_unregister(bus->p->devices_kset);
938bus_devices_fail:
939 bus_remove_file(bus, &bus_attr_uevent);
940bus_uevent_fail:
941 kset_unregister(&bus->p->subsys);
942out:
943 kfree(bus->p);
944 bus->p = NULL;
945 return retval;
946}
947EXPORT_SYMBOL_GPL(bus_register);
948
949/**
950 * bus_unregister - remove a bus from the system
951 * @bus: bus.
952 *
953 * Unregister the child subsystems and the bus itself.
954 * Finally, we call bus_put() to release the refcount
955 */
956void bus_unregister(struct bus_type *bus)
957{
958 pr_debug("bus: '%s': unregistering\n", bus->name);
959 if (bus->dev_root)
960 device_unregister(bus->dev_root);
961 bus_remove_groups(bus, bus->bus_groups);
962 remove_probe_files(bus);
963 kset_unregister(bus->p->drivers_kset);
964 kset_unregister(bus->p->devices_kset);
965 bus_remove_file(bus, &bus_attr_uevent);
966 kset_unregister(&bus->p->subsys);
967}
968EXPORT_SYMBOL_GPL(bus_unregister);
969
970int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
971{
972 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
973}
974EXPORT_SYMBOL_GPL(bus_register_notifier);
975
976int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
977{
978 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
979}
980EXPORT_SYMBOL_GPL(bus_unregister_notifier);
981
982struct kset *bus_get_kset(struct bus_type *bus)
983{
984 return &bus->p->subsys;
985}
986EXPORT_SYMBOL_GPL(bus_get_kset);
987
988struct klist *bus_get_device_klist(struct bus_type *bus)
989{
990 return &bus->p->klist_devices;
991}
992EXPORT_SYMBOL_GPL(bus_get_device_klist);
993
994/*
995 * Yes, this forcibly breaks the klist abstraction temporarily. It
996 * just wants to sort the klist, not change reference counts and
997 * take/drop locks rapidly in the process. It does all this while
998 * holding the lock for the list, so objects can't otherwise be
999 * added/removed while we're swizzling.
1000 */
1001static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1002 int (*compare)(const struct device *a,
1003 const struct device *b))
1004{
1005 struct list_head *pos;
1006 struct klist_node *n;
1007 struct device_private *dev_prv;
1008 struct device *b;
1009
1010 list_for_each(pos, list) {
1011 n = container_of(pos, struct klist_node, n_node);
1012 dev_prv = to_device_private_bus(n);
1013 b = dev_prv->device;
1014 if (compare(a, b) <= 0) {
1015 list_move_tail(&a->p->knode_bus.n_node,
1016 &b->p->knode_bus.n_node);
1017 return;
1018 }
1019 }
1020 list_move_tail(&a->p->knode_bus.n_node, list);
1021}
1022
1023void bus_sort_breadthfirst(struct bus_type *bus,
1024 int (*compare)(const struct device *a,
1025 const struct device *b))
1026{
1027 LIST_HEAD(sorted_devices);
1028 struct list_head *pos, *tmp;
1029 struct klist_node *n;
1030 struct device_private *dev_prv;
1031 struct device *dev;
1032 struct klist *device_klist;
1033
1034 device_klist = bus_get_device_klist(bus);
1035
1036 spin_lock(&device_klist->k_lock);
1037 list_for_each_safe(pos, tmp, &device_klist->k_list) {
1038 n = container_of(pos, struct klist_node, n_node);
1039 dev_prv = to_device_private_bus(n);
1040 dev = dev_prv->device;
1041 device_insertion_sort_klist(dev, &sorted_devices, compare);
1042 }
1043 list_splice(&sorted_devices, &device_klist->k_list);
1044 spin_unlock(&device_klist->k_lock);
1045}
1046EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1047
1048/**
1049 * subsys_dev_iter_init - initialize subsys device iterator
1050 * @iter: subsys iterator to initialize
1051 * @subsys: the subsys we wanna iterate over
1052 * @start: the device to start iterating from, if any
1053 * @type: device_type of the devices to iterate over, NULL for all
1054 *
1055 * Initialize subsys iterator @iter such that it iterates over devices
1056 * of @subsys. If @start is set, the list iteration will start there,
1057 * otherwise if it is NULL, the iteration starts at the beginning of
1058 * the list.
1059 */
1060void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1061 struct device *start, const struct device_type *type)
1062{
1063 struct klist_node *start_knode = NULL;
1064
1065 if (start)
1066 start_knode = &start->p->knode_bus;
1067 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1068 iter->type = type;
1069}
1070EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1071
1072/**
1073 * subsys_dev_iter_next - iterate to the next device
1074 * @iter: subsys iterator to proceed
1075 *
1076 * Proceed @iter to the next device and return it. Returns NULL if
1077 * iteration is complete.
1078 *
1079 * The returned device is referenced and won't be released till
1080 * iterator is proceed to the next device or exited. The caller is
1081 * free to do whatever it wants to do with the device including
1082 * calling back into subsys code.
1083 */
1084struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1085{
1086 struct klist_node *knode;
1087 struct device *dev;
1088
1089 for (;;) {
1090 knode = klist_next(&iter->ki);
1091 if (!knode)
1092 return NULL;
1093 dev = container_of(knode, struct device_private, knode_bus)->device;
1094 if (!iter->type || iter->type == dev->type)
1095 return dev;
1096 }
1097}
1098EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1099
1100/**
1101 * subsys_dev_iter_exit - finish iteration
1102 * @iter: subsys iterator to finish
1103 *
1104 * Finish an iteration. Always call this function after iteration is
1105 * complete whether the iteration ran till the end or not.
1106 */
1107void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1108{
1109 klist_iter_exit(&iter->ki);
1110}
1111EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1112
1113int subsys_interface_register(struct subsys_interface *sif)
1114{
1115 struct bus_type *subsys;
1116 struct subsys_dev_iter iter;
1117 struct device *dev;
1118
1119 if (!sif || !sif->subsys)
1120 return -ENODEV;
1121
1122 subsys = bus_get(sif->subsys);
1123 if (!subsys)
1124 return -EINVAL;
1125
1126 mutex_lock(&subsys->p->mutex);
1127 list_add_tail(&sif->node, &subsys->p->interfaces);
1128 if (sif->add_dev) {
1129 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1130 while ((dev = subsys_dev_iter_next(&iter)))
1131 sif->add_dev(dev, sif);
1132 subsys_dev_iter_exit(&iter);
1133 }
1134 mutex_unlock(&subsys->p->mutex);
1135
1136 return 0;
1137}
1138EXPORT_SYMBOL_GPL(subsys_interface_register);
1139
1140void subsys_interface_unregister(struct subsys_interface *sif)
1141{
1142 struct bus_type *subsys;
1143 struct subsys_dev_iter iter;
1144 struct device *dev;
1145
1146 if (!sif || !sif->subsys)
1147 return;
1148
1149 subsys = sif->subsys;
1150
1151 mutex_lock(&subsys->p->mutex);
1152 list_del_init(&sif->node);
1153 if (sif->remove_dev) {
1154 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1155 while ((dev = subsys_dev_iter_next(&iter)))
1156 sif->remove_dev(dev, sif);
1157 subsys_dev_iter_exit(&iter);
1158 }
1159 mutex_unlock(&subsys->p->mutex);
1160
1161 bus_put(subsys);
1162}
1163EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1164
1165static void system_root_device_release(struct device *dev)
1166{
1167 kfree(dev);
1168}
1169
1170static int subsys_register(struct bus_type *subsys,
1171 const struct attribute_group **groups,
1172 struct kobject *parent_of_root)
1173{
1174 struct device *dev;
1175 int err;
1176
1177 err = bus_register(subsys);
1178 if (err < 0)
1179 return err;
1180
1181 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1182 if (!dev) {
1183 err = -ENOMEM;
1184 goto err_dev;
1185 }
1186
1187 err = dev_set_name(dev, "%s", subsys->name);
1188 if (err < 0)
1189 goto err_name;
1190
1191 dev->kobj.parent = parent_of_root;
1192 dev->groups = groups;
1193 dev->release = system_root_device_release;
1194
1195 err = device_register(dev);
1196 if (err < 0)
1197 goto err_dev_reg;
1198
1199 subsys->dev_root = dev;
1200 return 0;
1201
1202err_dev_reg:
1203 put_device(dev);
1204 dev = NULL;
1205err_name:
1206 kfree(dev);
1207err_dev:
1208 bus_unregister(subsys);
1209 return err;
1210}
1211
1212/**
1213 * subsys_system_register - register a subsystem at /sys/devices/system/
1214 * @subsys: system subsystem
1215 * @groups: default attributes for the root device
1216 *
1217 * All 'system' subsystems have a /sys/devices/system/<name> root device
1218 * with the name of the subsystem. The root device can carry subsystem-
1219 * wide attributes. All registered devices are below this single root
1220 * device and are named after the subsystem with a simple enumeration
1221 * number appended. The registered devices are not explicitly named;
1222 * only 'id' in the device needs to be set.
1223 *
1224 * Do not use this interface for anything new, it exists for compatibility
1225 * with bad ideas only. New subsystems should use plain subsystems; and
1226 * add the subsystem-wide attributes should be added to the subsystem
1227 * directory itself and not some create fake root-device placed in
1228 * /sys/devices/system/<name>.
1229 */
1230int subsys_system_register(struct bus_type *subsys,
1231 const struct attribute_group **groups)
1232{
1233 return subsys_register(subsys, groups, &system_kset->kobj);
1234}
1235EXPORT_SYMBOL_GPL(subsys_system_register);
1236
1237/**
1238 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1239 * @subsys: virtual subsystem
1240 * @groups: default attributes for the root device
1241 *
1242 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1243 * with the name of the subystem. The root device can carry subsystem-wide
1244 * attributes. All registered devices are below this single root device.
1245 * There's no restriction on device naming. This is for kernel software
1246 * constructs which need sysfs interface.
1247 */
1248int subsys_virtual_register(struct bus_type *subsys,
1249 const struct attribute_group **groups)
1250{
1251 struct kobject *virtual_dir;
1252
1253 virtual_dir = virtual_device_parent(NULL);
1254 if (!virtual_dir)
1255 return -ENOMEM;
1256
1257 return subsys_register(subsys, groups, virtual_dir);
1258}
1259EXPORT_SYMBOL_GPL(subsys_virtual_register);
1260
1261int __init buses_init(void)
1262{
1263 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1264 if (!bus_kset)
1265 return -ENOMEM;
1266
1267 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1268 if (!system_kset)
1269 return -ENOMEM;
1270
1271 return 0;
1272}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * bus.c - bus driver management
4 *
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
8 * Copyright (c) 2007 Novell Inc.
9 * Copyright (c) 2023 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
10 */
11
12#include <linux/async.h>
13#include <linux/device/bus.h>
14#include <linux/device.h>
15#include <linux/module.h>
16#include <linux/errno.h>
17#include <linux/slab.h>
18#include <linux/init.h>
19#include <linux/string.h>
20#include <linux/mutex.h>
21#include <linux/sysfs.h>
22#include "base.h"
23#include "power/power.h"
24
25/* /sys/devices/system */
26static struct kset *system_kset;
27
28/* /sys/bus */
29static struct kset *bus_kset;
30
31#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
32
33/*
34 * sysfs bindings for drivers
35 */
36
37#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
38
39#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
40 struct driver_attribute driver_attr_##_name = \
41 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
42
43static int __must_check bus_rescan_devices_helper(struct device *dev,
44 void *data);
45
46/**
47 * bus_to_subsys - Turn a struct bus_type into a struct subsys_private
48 *
49 * @bus: pointer to the struct bus_type to look up
50 *
51 * The driver core internals needs to work on the subsys_private structure, not
52 * the external struct bus_type pointer. This function walks the list of
53 * registered busses in the system and finds the matching one and returns the
54 * internal struct subsys_private that relates to that bus.
55 *
56 * Note, the reference count of the return value is INCREMENTED if it is not
57 * NULL. A call to subsys_put() must be done when finished with the pointer in
58 * order for it to be properly freed.
59 */
60static struct subsys_private *bus_to_subsys(const struct bus_type *bus)
61{
62 struct subsys_private *sp = NULL;
63 struct kobject *kobj;
64
65 if (!bus || !bus_kset)
66 return NULL;
67
68 spin_lock(&bus_kset->list_lock);
69
70 if (list_empty(&bus_kset->list))
71 goto done;
72
73 list_for_each_entry(kobj, &bus_kset->list, entry) {
74 struct kset *kset = container_of(kobj, struct kset, kobj);
75
76 sp = container_of_const(kset, struct subsys_private, subsys);
77 if (sp->bus == bus)
78 goto done;
79 }
80 sp = NULL;
81done:
82 sp = subsys_get(sp);
83 spin_unlock(&bus_kset->list_lock);
84 return sp;
85}
86
87static const struct bus_type *bus_get(const struct bus_type *bus)
88{
89 struct subsys_private *sp = bus_to_subsys(bus);
90
91 if (sp)
92 return bus;
93 return NULL;
94}
95
96static void bus_put(const struct bus_type *bus)
97{
98 struct subsys_private *sp = bus_to_subsys(bus);
99
100 /* two puts are required as the call to bus_to_subsys incremented it again */
101 subsys_put(sp);
102 subsys_put(sp);
103}
104
105static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
106 char *buf)
107{
108 struct driver_attribute *drv_attr = to_drv_attr(attr);
109 struct driver_private *drv_priv = to_driver(kobj);
110 ssize_t ret = -EIO;
111
112 if (drv_attr->show)
113 ret = drv_attr->show(drv_priv->driver, buf);
114 return ret;
115}
116
117static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
118 const char *buf, size_t count)
119{
120 struct driver_attribute *drv_attr = to_drv_attr(attr);
121 struct driver_private *drv_priv = to_driver(kobj);
122 ssize_t ret = -EIO;
123
124 if (drv_attr->store)
125 ret = drv_attr->store(drv_priv->driver, buf, count);
126 return ret;
127}
128
129static const struct sysfs_ops driver_sysfs_ops = {
130 .show = drv_attr_show,
131 .store = drv_attr_store,
132};
133
134static void driver_release(struct kobject *kobj)
135{
136 struct driver_private *drv_priv = to_driver(kobj);
137
138 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
139 kfree(drv_priv);
140}
141
142static const struct kobj_type driver_ktype = {
143 .sysfs_ops = &driver_sysfs_ops,
144 .release = driver_release,
145};
146
147/*
148 * sysfs bindings for buses
149 */
150static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
151 char *buf)
152{
153 struct bus_attribute *bus_attr = to_bus_attr(attr);
154 struct subsys_private *subsys_priv = to_subsys_private(kobj);
155 /* return -EIO for reading a bus attribute without show() */
156 ssize_t ret = -EIO;
157
158 if (bus_attr->show)
159 ret = bus_attr->show(subsys_priv->bus, buf);
160 return ret;
161}
162
163static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
164 const char *buf, size_t count)
165{
166 struct bus_attribute *bus_attr = to_bus_attr(attr);
167 struct subsys_private *subsys_priv = to_subsys_private(kobj);
168 /* return -EIO for writing a bus attribute without store() */
169 ssize_t ret = -EIO;
170
171 if (bus_attr->store)
172 ret = bus_attr->store(subsys_priv->bus, buf, count);
173 return ret;
174}
175
176static const struct sysfs_ops bus_sysfs_ops = {
177 .show = bus_attr_show,
178 .store = bus_attr_store,
179};
180
181int bus_create_file(const struct bus_type *bus, struct bus_attribute *attr)
182{
183 struct subsys_private *sp = bus_to_subsys(bus);
184 int error;
185
186 if (!sp)
187 return -EINVAL;
188
189 error = sysfs_create_file(&sp->subsys.kobj, &attr->attr);
190
191 subsys_put(sp);
192 return error;
193}
194EXPORT_SYMBOL_GPL(bus_create_file);
195
196void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr)
197{
198 struct subsys_private *sp = bus_to_subsys(bus);
199
200 if (!sp)
201 return;
202
203 sysfs_remove_file(&sp->subsys.kobj, &attr->attr);
204 subsys_put(sp);
205}
206EXPORT_SYMBOL_GPL(bus_remove_file);
207
208static void bus_release(struct kobject *kobj)
209{
210 struct subsys_private *priv = to_subsys_private(kobj);
211
212 lockdep_unregister_key(&priv->lock_key);
213 kfree(priv);
214}
215
216static const struct kobj_type bus_ktype = {
217 .sysfs_ops = &bus_sysfs_ops,
218 .release = bus_release,
219};
220
221static int bus_uevent_filter(const struct kobject *kobj)
222{
223 const struct kobj_type *ktype = get_ktype(kobj);
224
225 if (ktype == &bus_ktype)
226 return 1;
227 return 0;
228}
229
230static const struct kset_uevent_ops bus_uevent_ops = {
231 .filter = bus_uevent_filter,
232};
233
234/* Manually detach a device from its associated driver. */
235static ssize_t unbind_store(struct device_driver *drv, const char *buf,
236 size_t count)
237{
238 const struct bus_type *bus = bus_get(drv->bus);
239 struct device *dev;
240 int err = -ENODEV;
241
242 dev = bus_find_device_by_name(bus, NULL, buf);
243 if (dev && dev->driver == drv) {
244 device_driver_detach(dev);
245 err = count;
246 }
247 put_device(dev);
248 bus_put(bus);
249 return err;
250}
251static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
252
253/*
254 * Manually attach a device to a driver.
255 * Note: the driver must want to bind to the device,
256 * it is not possible to override the driver's id table.
257 */
258static ssize_t bind_store(struct device_driver *drv, const char *buf,
259 size_t count)
260{
261 const struct bus_type *bus = bus_get(drv->bus);
262 struct device *dev;
263 int err = -ENODEV;
264
265 dev = bus_find_device_by_name(bus, NULL, buf);
266 if (dev && driver_match_device(drv, dev)) {
267 err = device_driver_attach(drv, dev);
268 if (!err) {
269 /* success */
270 err = count;
271 }
272 }
273 put_device(dev);
274 bus_put(bus);
275 return err;
276}
277static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
278
279static ssize_t drivers_autoprobe_show(const struct bus_type *bus, char *buf)
280{
281 struct subsys_private *sp = bus_to_subsys(bus);
282 int ret;
283
284 if (!sp)
285 return -EINVAL;
286
287 ret = sysfs_emit(buf, "%d\n", sp->drivers_autoprobe);
288 subsys_put(sp);
289 return ret;
290}
291
292static ssize_t drivers_autoprobe_store(const struct bus_type *bus,
293 const char *buf, size_t count)
294{
295 struct subsys_private *sp = bus_to_subsys(bus);
296
297 if (!sp)
298 return -EINVAL;
299
300 if (buf[0] == '0')
301 sp->drivers_autoprobe = 0;
302 else
303 sp->drivers_autoprobe = 1;
304
305 subsys_put(sp);
306 return count;
307}
308
309static ssize_t drivers_probe_store(const struct bus_type *bus,
310 const char *buf, size_t count)
311{
312 struct device *dev;
313 int err = -EINVAL;
314
315 dev = bus_find_device_by_name(bus, NULL, buf);
316 if (!dev)
317 return -ENODEV;
318 if (bus_rescan_devices_helper(dev, NULL) == 0)
319 err = count;
320 put_device(dev);
321 return err;
322}
323
324static struct device *next_device(struct klist_iter *i)
325{
326 struct klist_node *n = klist_next(i);
327 struct device *dev = NULL;
328 struct device_private *dev_prv;
329
330 if (n) {
331 dev_prv = to_device_private_bus(n);
332 dev = dev_prv->device;
333 }
334 return dev;
335}
336
337/**
338 * bus_for_each_dev - device iterator.
339 * @bus: bus type.
340 * @start: device to start iterating from.
341 * @data: data for the callback.
342 * @fn: function to be called for each device.
343 *
344 * Iterate over @bus's list of devices, and call @fn for each,
345 * passing it @data. If @start is not NULL, we use that device to
346 * begin iterating from.
347 *
348 * We check the return of @fn each time. If it returns anything
349 * other than 0, we break out and return that value.
350 *
351 * NOTE: The device that returns a non-zero value is not retained
352 * in any way, nor is its refcount incremented. If the caller needs
353 * to retain this data, it should do so, and increment the reference
354 * count in the supplied callback.
355 */
356int bus_for_each_dev(const struct bus_type *bus, struct device *start,
357 void *data, int (*fn)(struct device *, void *))
358{
359 struct subsys_private *sp = bus_to_subsys(bus);
360 struct klist_iter i;
361 struct device *dev;
362 int error = 0;
363
364 if (!sp)
365 return -EINVAL;
366
367 klist_iter_init_node(&sp->klist_devices, &i,
368 (start ? &start->p->knode_bus : NULL));
369 while (!error && (dev = next_device(&i)))
370 error = fn(dev, data);
371 klist_iter_exit(&i);
372 subsys_put(sp);
373 return error;
374}
375EXPORT_SYMBOL_GPL(bus_for_each_dev);
376
377/**
378 * bus_find_device - device iterator for locating a particular device.
379 * @bus: bus type
380 * @start: Device to begin with
381 * @data: Data to pass to match function
382 * @match: Callback function to check device
383 *
384 * This is similar to the bus_for_each_dev() function above, but it
385 * returns a reference to a device that is 'found' for later use, as
386 * determined by the @match callback.
387 *
388 * The callback should return 0 if the device doesn't match and non-zero
389 * if it does. If the callback returns non-zero, this function will
390 * return to the caller and not iterate over any more devices.
391 */
392struct device *bus_find_device(const struct bus_type *bus,
393 struct device *start, const void *data,
394 device_match_t match)
395{
396 struct subsys_private *sp = bus_to_subsys(bus);
397 struct klist_iter i;
398 struct device *dev;
399
400 if (!sp)
401 return NULL;
402
403 klist_iter_init_node(&sp->klist_devices, &i,
404 (start ? &start->p->knode_bus : NULL));
405 while ((dev = next_device(&i)))
406 if (match(dev, data) && get_device(dev))
407 break;
408 klist_iter_exit(&i);
409 subsys_put(sp);
410 return dev;
411}
412EXPORT_SYMBOL_GPL(bus_find_device);
413
414static struct device_driver *next_driver(struct klist_iter *i)
415{
416 struct klist_node *n = klist_next(i);
417 struct driver_private *drv_priv;
418
419 if (n) {
420 drv_priv = container_of(n, struct driver_private, knode_bus);
421 return drv_priv->driver;
422 }
423 return NULL;
424}
425
426/**
427 * bus_for_each_drv - driver iterator
428 * @bus: bus we're dealing with.
429 * @start: driver to start iterating on.
430 * @data: data to pass to the callback.
431 * @fn: function to call for each driver.
432 *
433 * This is nearly identical to the device iterator above.
434 * We iterate over each driver that belongs to @bus, and call
435 * @fn for each. If @fn returns anything but 0, we break out
436 * and return it. If @start is not NULL, we use it as the head
437 * of the list.
438 *
439 * NOTE: we don't return the driver that returns a non-zero
440 * value, nor do we leave the reference count incremented for that
441 * driver. If the caller needs to know that info, it must set it
442 * in the callback. It must also be sure to increment the refcount
443 * so it doesn't disappear before returning to the caller.
444 */
445int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start,
446 void *data, int (*fn)(struct device_driver *, void *))
447{
448 struct subsys_private *sp = bus_to_subsys(bus);
449 struct klist_iter i;
450 struct device_driver *drv;
451 int error = 0;
452
453 if (!sp)
454 return -EINVAL;
455
456 klist_iter_init_node(&sp->klist_drivers, &i,
457 start ? &start->p->knode_bus : NULL);
458 while ((drv = next_driver(&i)) && !error)
459 error = fn(drv, data);
460 klist_iter_exit(&i);
461 subsys_put(sp);
462 return error;
463}
464EXPORT_SYMBOL_GPL(bus_for_each_drv);
465
466/**
467 * bus_add_device - add device to bus
468 * @dev: device being added
469 *
470 * - Add device's bus attributes.
471 * - Create links to device's bus.
472 * - Add the device to its bus's list of devices.
473 */
474int bus_add_device(struct device *dev)
475{
476 struct subsys_private *sp = bus_to_subsys(dev->bus);
477 int error;
478
479 if (!sp) {
480 /*
481 * This is a normal operation for many devices that do not
482 * have a bus assigned to them, just say that all went
483 * well.
484 */
485 return 0;
486 }
487
488 /*
489 * Reference in sp is now incremented and will be dropped when
490 * the device is removed from the bus
491 */
492
493 pr_debug("bus: '%s': add device %s\n", sp->bus->name, dev_name(dev));
494
495 error = device_add_groups(dev, sp->bus->dev_groups);
496 if (error)
497 goto out_put;
498
499 error = sysfs_create_link(&sp->devices_kset->kobj, &dev->kobj, dev_name(dev));
500 if (error)
501 goto out_groups;
502
503 error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
504 if (error)
505 goto out_subsys;
506
507 klist_add_tail(&dev->p->knode_bus, &sp->klist_devices);
508 return 0;
509
510out_subsys:
511 sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
512out_groups:
513 device_remove_groups(dev, sp->bus->dev_groups);
514out_put:
515 subsys_put(sp);
516 return error;
517}
518
519/**
520 * bus_probe_device - probe drivers for a new device
521 * @dev: device to probe
522 *
523 * - Automatically probe for a driver if the bus allows it.
524 */
525void bus_probe_device(struct device *dev)
526{
527 struct subsys_private *sp = bus_to_subsys(dev->bus);
528 struct subsys_interface *sif;
529
530 if (!sp)
531 return;
532
533 if (sp->drivers_autoprobe)
534 device_initial_probe(dev);
535
536 mutex_lock(&sp->mutex);
537 list_for_each_entry(sif, &sp->interfaces, node)
538 if (sif->add_dev)
539 sif->add_dev(dev, sif);
540 mutex_unlock(&sp->mutex);
541 subsys_put(sp);
542}
543
544/**
545 * bus_remove_device - remove device from bus
546 * @dev: device to be removed
547 *
548 * - Remove device from all interfaces.
549 * - Remove symlink from bus' directory.
550 * - Delete device from bus's list.
551 * - Detach from its driver.
552 * - Drop reference taken in bus_add_device().
553 */
554void bus_remove_device(struct device *dev)
555{
556 struct subsys_private *sp = bus_to_subsys(dev->bus);
557 struct subsys_interface *sif;
558
559 if (!sp)
560 return;
561
562 mutex_lock(&sp->mutex);
563 list_for_each_entry(sif, &sp->interfaces, node)
564 if (sif->remove_dev)
565 sif->remove_dev(dev, sif);
566 mutex_unlock(&sp->mutex);
567
568 sysfs_remove_link(&dev->kobj, "subsystem");
569 sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
570 device_remove_groups(dev, dev->bus->dev_groups);
571 if (klist_node_attached(&dev->p->knode_bus))
572 klist_del(&dev->p->knode_bus);
573
574 pr_debug("bus: '%s': remove device %s\n",
575 dev->bus->name, dev_name(dev));
576 device_release_driver(dev);
577
578 /*
579 * Decrement the reference count twice, once for the bus_to_subsys()
580 * call in the start of this function, and the second one from the
581 * reference increment in bus_add_device()
582 */
583 subsys_put(sp);
584 subsys_put(sp);
585}
586
587static int __must_check add_bind_files(struct device_driver *drv)
588{
589 int ret;
590
591 ret = driver_create_file(drv, &driver_attr_unbind);
592 if (ret == 0) {
593 ret = driver_create_file(drv, &driver_attr_bind);
594 if (ret)
595 driver_remove_file(drv, &driver_attr_unbind);
596 }
597 return ret;
598}
599
600static void remove_bind_files(struct device_driver *drv)
601{
602 driver_remove_file(drv, &driver_attr_bind);
603 driver_remove_file(drv, &driver_attr_unbind);
604}
605
606static BUS_ATTR_WO(drivers_probe);
607static BUS_ATTR_RW(drivers_autoprobe);
608
609static int add_probe_files(const struct bus_type *bus)
610{
611 int retval;
612
613 retval = bus_create_file(bus, &bus_attr_drivers_probe);
614 if (retval)
615 goto out;
616
617 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
618 if (retval)
619 bus_remove_file(bus, &bus_attr_drivers_probe);
620out:
621 return retval;
622}
623
624static void remove_probe_files(const struct bus_type *bus)
625{
626 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
627 bus_remove_file(bus, &bus_attr_drivers_probe);
628}
629
630static ssize_t uevent_store(struct device_driver *drv, const char *buf,
631 size_t count)
632{
633 int rc;
634
635 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
636 return rc ? rc : count;
637}
638static DRIVER_ATTR_WO(uevent);
639
640/**
641 * bus_add_driver - Add a driver to the bus.
642 * @drv: driver.
643 */
644int bus_add_driver(struct device_driver *drv)
645{
646 struct subsys_private *sp = bus_to_subsys(drv->bus);
647 struct driver_private *priv;
648 int error = 0;
649
650 if (!sp)
651 return -EINVAL;
652
653 /*
654 * Reference in sp is now incremented and will be dropped when
655 * the driver is removed from the bus
656 */
657 pr_debug("bus: '%s': add driver %s\n", sp->bus->name, drv->name);
658
659 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
660 if (!priv) {
661 error = -ENOMEM;
662 goto out_put_bus;
663 }
664 klist_init(&priv->klist_devices, NULL, NULL);
665 priv->driver = drv;
666 drv->p = priv;
667 priv->kobj.kset = sp->drivers_kset;
668 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
669 "%s", drv->name);
670 if (error)
671 goto out_unregister;
672
673 klist_add_tail(&priv->knode_bus, &sp->klist_drivers);
674 if (sp->drivers_autoprobe) {
675 error = driver_attach(drv);
676 if (error)
677 goto out_del_list;
678 }
679 error = module_add_driver(drv->owner, drv);
680 if (error) {
681 printk(KERN_ERR "%s: failed to create module links for %s\n",
682 __func__, drv->name);
683 goto out_detach;
684 }
685
686 error = driver_create_file(drv, &driver_attr_uevent);
687 if (error) {
688 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
689 __func__, drv->name);
690 }
691 error = driver_add_groups(drv, sp->bus->drv_groups);
692 if (error) {
693 /* How the hell do we get out of this pickle? Give up */
694 printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
695 __func__, drv->name);
696 }
697
698 if (!drv->suppress_bind_attrs) {
699 error = add_bind_files(drv);
700 if (error) {
701 /* Ditto */
702 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
703 __func__, drv->name);
704 }
705 }
706
707 return 0;
708
709out_detach:
710 driver_detach(drv);
711out_del_list:
712 klist_del(&priv->knode_bus);
713out_unregister:
714 kobject_put(&priv->kobj);
715 /* drv->p is freed in driver_release() */
716 drv->p = NULL;
717out_put_bus:
718 subsys_put(sp);
719 return error;
720}
721
722/**
723 * bus_remove_driver - delete driver from bus's knowledge.
724 * @drv: driver.
725 *
726 * Detach the driver from the devices it controls, and remove
727 * it from its bus's list of drivers. Finally, we drop the reference
728 * to the bus we took in bus_add_driver().
729 */
730void bus_remove_driver(struct device_driver *drv)
731{
732 struct subsys_private *sp = bus_to_subsys(drv->bus);
733
734 if (!sp)
735 return;
736
737 pr_debug("bus: '%s': remove driver %s\n", sp->bus->name, drv->name);
738
739 if (!drv->suppress_bind_attrs)
740 remove_bind_files(drv);
741 driver_remove_groups(drv, sp->bus->drv_groups);
742 driver_remove_file(drv, &driver_attr_uevent);
743 klist_remove(&drv->p->knode_bus);
744 driver_detach(drv);
745 module_remove_driver(drv);
746 kobject_put(&drv->p->kobj);
747
748 /*
749 * Decrement the reference count twice, once for the bus_to_subsys()
750 * call in the start of this function, and the second one from the
751 * reference increment in bus_add_driver()
752 */
753 subsys_put(sp);
754 subsys_put(sp);
755}
756
757/* Helper for bus_rescan_devices's iter */
758static int __must_check bus_rescan_devices_helper(struct device *dev,
759 void *data)
760{
761 int ret = 0;
762
763 if (!dev->driver) {
764 if (dev->parent && dev->bus->need_parent_lock)
765 device_lock(dev->parent);
766 ret = device_attach(dev);
767 if (dev->parent && dev->bus->need_parent_lock)
768 device_unlock(dev->parent);
769 }
770 return ret < 0 ? ret : 0;
771}
772
773/**
774 * bus_rescan_devices - rescan devices on the bus for possible drivers
775 * @bus: the bus to scan.
776 *
777 * This function will look for devices on the bus with no driver
778 * attached and rescan it against existing drivers to see if it matches
779 * any by calling device_attach() for the unbound devices.
780 */
781int bus_rescan_devices(const struct bus_type *bus)
782{
783 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
784}
785EXPORT_SYMBOL_GPL(bus_rescan_devices);
786
787/**
788 * device_reprobe - remove driver for a device and probe for a new driver
789 * @dev: the device to reprobe
790 *
791 * This function detaches the attached driver (if any) for the given
792 * device and restarts the driver probing process. It is intended
793 * to use if probing criteria changed during a devices lifetime and
794 * driver attachment should change accordingly.
795 */
796int device_reprobe(struct device *dev)
797{
798 if (dev->driver)
799 device_driver_detach(dev);
800 return bus_rescan_devices_helper(dev, NULL);
801}
802EXPORT_SYMBOL_GPL(device_reprobe);
803
804static void klist_devices_get(struct klist_node *n)
805{
806 struct device_private *dev_prv = to_device_private_bus(n);
807 struct device *dev = dev_prv->device;
808
809 get_device(dev);
810}
811
812static void klist_devices_put(struct klist_node *n)
813{
814 struct device_private *dev_prv = to_device_private_bus(n);
815 struct device *dev = dev_prv->device;
816
817 put_device(dev);
818}
819
820static ssize_t bus_uevent_store(const struct bus_type *bus,
821 const char *buf, size_t count)
822{
823 struct subsys_private *sp = bus_to_subsys(bus);
824 int ret;
825
826 if (!sp)
827 return -EINVAL;
828
829 ret = kobject_synth_uevent(&sp->subsys.kobj, buf, count);
830 subsys_put(sp);
831
832 if (ret)
833 return ret;
834 return count;
835}
836/*
837 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
838 * here, but can not use it as earlier in the file we have
839 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
840 * function name.
841 */
842static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
843 bus_uevent_store);
844
845/**
846 * bus_register - register a driver-core subsystem
847 * @bus: bus to register
848 *
849 * Once we have that, we register the bus with the kobject
850 * infrastructure, then register the children subsystems it has:
851 * the devices and drivers that belong to the subsystem.
852 */
853int bus_register(const struct bus_type *bus)
854{
855 int retval;
856 struct subsys_private *priv;
857 struct kobject *bus_kobj;
858 struct lock_class_key *key;
859
860 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
861 if (!priv)
862 return -ENOMEM;
863
864 priv->bus = bus;
865
866 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
867
868 bus_kobj = &priv->subsys.kobj;
869 retval = kobject_set_name(bus_kobj, "%s", bus->name);
870 if (retval)
871 goto out;
872
873 bus_kobj->kset = bus_kset;
874 bus_kobj->ktype = &bus_ktype;
875 priv->drivers_autoprobe = 1;
876
877 retval = kset_register(&priv->subsys);
878 if (retval)
879 goto out;
880
881 retval = bus_create_file(bus, &bus_attr_uevent);
882 if (retval)
883 goto bus_uevent_fail;
884
885 priv->devices_kset = kset_create_and_add("devices", NULL, bus_kobj);
886 if (!priv->devices_kset) {
887 retval = -ENOMEM;
888 goto bus_devices_fail;
889 }
890
891 priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj);
892 if (!priv->drivers_kset) {
893 retval = -ENOMEM;
894 goto bus_drivers_fail;
895 }
896
897 INIT_LIST_HEAD(&priv->interfaces);
898 key = &priv->lock_key;
899 lockdep_register_key(key);
900 __mutex_init(&priv->mutex, "subsys mutex", key);
901 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
902 klist_init(&priv->klist_drivers, NULL, NULL);
903
904 retval = add_probe_files(bus);
905 if (retval)
906 goto bus_probe_files_fail;
907
908 retval = sysfs_create_groups(bus_kobj, bus->bus_groups);
909 if (retval)
910 goto bus_groups_fail;
911
912 pr_debug("bus: '%s': registered\n", bus->name);
913 return 0;
914
915bus_groups_fail:
916 remove_probe_files(bus);
917bus_probe_files_fail:
918 kset_unregister(priv->drivers_kset);
919bus_drivers_fail:
920 kset_unregister(priv->devices_kset);
921bus_devices_fail:
922 bus_remove_file(bus, &bus_attr_uevent);
923bus_uevent_fail:
924 kset_unregister(&priv->subsys);
925 /* Above kset_unregister() will kfree @priv */
926 priv = NULL;
927out:
928 kfree(priv);
929 return retval;
930}
931EXPORT_SYMBOL_GPL(bus_register);
932
933/**
934 * bus_unregister - remove a bus from the system
935 * @bus: bus.
936 *
937 * Unregister the child subsystems and the bus itself.
938 * Finally, we call bus_put() to release the refcount
939 */
940void bus_unregister(const struct bus_type *bus)
941{
942 struct subsys_private *sp = bus_to_subsys(bus);
943 struct kobject *bus_kobj;
944
945 if (!sp)
946 return;
947
948 pr_debug("bus: '%s': unregistering\n", bus->name);
949 if (sp->dev_root)
950 device_unregister(sp->dev_root);
951
952 bus_kobj = &sp->subsys.kobj;
953 sysfs_remove_groups(bus_kobj, bus->bus_groups);
954 remove_probe_files(bus);
955 bus_remove_file(bus, &bus_attr_uevent);
956
957 kset_unregister(sp->drivers_kset);
958 kset_unregister(sp->devices_kset);
959 kset_unregister(&sp->subsys);
960 subsys_put(sp);
961}
962EXPORT_SYMBOL_GPL(bus_unregister);
963
964int bus_register_notifier(const struct bus_type *bus, struct notifier_block *nb)
965{
966 struct subsys_private *sp = bus_to_subsys(bus);
967 int retval;
968
969 if (!sp)
970 return -EINVAL;
971
972 retval = blocking_notifier_chain_register(&sp->bus_notifier, nb);
973 subsys_put(sp);
974 return retval;
975}
976EXPORT_SYMBOL_GPL(bus_register_notifier);
977
978int bus_unregister_notifier(const struct bus_type *bus, struct notifier_block *nb)
979{
980 struct subsys_private *sp = bus_to_subsys(bus);
981 int retval;
982
983 if (!sp)
984 return -EINVAL;
985 retval = blocking_notifier_chain_unregister(&sp->bus_notifier, nb);
986 subsys_put(sp);
987 return retval;
988}
989EXPORT_SYMBOL_GPL(bus_unregister_notifier);
990
991void bus_notify(struct device *dev, enum bus_notifier_event value)
992{
993 struct subsys_private *sp = bus_to_subsys(dev->bus);
994
995 if (!sp)
996 return;
997
998 blocking_notifier_call_chain(&sp->bus_notifier, value, dev);
999 subsys_put(sp);
1000}
1001
1002struct kset *bus_get_kset(const struct bus_type *bus)
1003{
1004 struct subsys_private *sp = bus_to_subsys(bus);
1005 struct kset *kset;
1006
1007 if (!sp)
1008 return NULL;
1009
1010 kset = &sp->subsys;
1011 subsys_put(sp);
1012
1013 return kset;
1014}
1015EXPORT_SYMBOL_GPL(bus_get_kset);
1016
1017/*
1018 * Yes, this forcibly breaks the klist abstraction temporarily. It
1019 * just wants to sort the klist, not change reference counts and
1020 * take/drop locks rapidly in the process. It does all this while
1021 * holding the lock for the list, so objects can't otherwise be
1022 * added/removed while we're swizzling.
1023 */
1024static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1025 int (*compare)(const struct device *a,
1026 const struct device *b))
1027{
1028 struct klist_node *n;
1029 struct device_private *dev_prv;
1030 struct device *b;
1031
1032 list_for_each_entry(n, list, n_node) {
1033 dev_prv = to_device_private_bus(n);
1034 b = dev_prv->device;
1035 if (compare(a, b) <= 0) {
1036 list_move_tail(&a->p->knode_bus.n_node,
1037 &b->p->knode_bus.n_node);
1038 return;
1039 }
1040 }
1041 list_move_tail(&a->p->knode_bus.n_node, list);
1042}
1043
1044void bus_sort_breadthfirst(const struct bus_type *bus,
1045 int (*compare)(const struct device *a,
1046 const struct device *b))
1047{
1048 struct subsys_private *sp = bus_to_subsys(bus);
1049 LIST_HEAD(sorted_devices);
1050 struct klist_node *n, *tmp;
1051 struct device_private *dev_prv;
1052 struct device *dev;
1053 struct klist *device_klist;
1054
1055 if (!sp)
1056 return;
1057 device_klist = &sp->klist_devices;
1058
1059 spin_lock(&device_klist->k_lock);
1060 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
1061 dev_prv = to_device_private_bus(n);
1062 dev = dev_prv->device;
1063 device_insertion_sort_klist(dev, &sorted_devices, compare);
1064 }
1065 list_splice(&sorted_devices, &device_klist->k_list);
1066 spin_unlock(&device_klist->k_lock);
1067 subsys_put(sp);
1068}
1069EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1070
1071struct subsys_dev_iter {
1072 struct klist_iter ki;
1073 const struct device_type *type;
1074};
1075
1076/**
1077 * subsys_dev_iter_init - initialize subsys device iterator
1078 * @iter: subsys iterator to initialize
1079 * @sp: the subsys private (i.e. bus) we wanna iterate over
1080 * @start: the device to start iterating from, if any
1081 * @type: device_type of the devices to iterate over, NULL for all
1082 *
1083 * Initialize subsys iterator @iter such that it iterates over devices
1084 * of @subsys. If @start is set, the list iteration will start there,
1085 * otherwise if it is NULL, the iteration starts at the beginning of
1086 * the list.
1087 */
1088static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct subsys_private *sp,
1089 struct device *start, const struct device_type *type)
1090{
1091 struct klist_node *start_knode = NULL;
1092
1093 if (start)
1094 start_knode = &start->p->knode_bus;
1095 klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
1096 iter->type = type;
1097}
1098
1099/**
1100 * subsys_dev_iter_next - iterate to the next device
1101 * @iter: subsys iterator to proceed
1102 *
1103 * Proceed @iter to the next device and return it. Returns NULL if
1104 * iteration is complete.
1105 *
1106 * The returned device is referenced and won't be released till
1107 * iterator is proceed to the next device or exited. The caller is
1108 * free to do whatever it wants to do with the device including
1109 * calling back into subsys code.
1110 */
1111static struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1112{
1113 struct klist_node *knode;
1114 struct device *dev;
1115
1116 for (;;) {
1117 knode = klist_next(&iter->ki);
1118 if (!knode)
1119 return NULL;
1120 dev = to_device_private_bus(knode)->device;
1121 if (!iter->type || iter->type == dev->type)
1122 return dev;
1123 }
1124}
1125
1126/**
1127 * subsys_dev_iter_exit - finish iteration
1128 * @iter: subsys iterator to finish
1129 *
1130 * Finish an iteration. Always call this function after iteration is
1131 * complete whether the iteration ran till the end or not.
1132 */
1133static void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1134{
1135 klist_iter_exit(&iter->ki);
1136}
1137
1138int subsys_interface_register(struct subsys_interface *sif)
1139{
1140 struct subsys_private *sp;
1141 struct subsys_dev_iter iter;
1142 struct device *dev;
1143
1144 if (!sif || !sif->subsys)
1145 return -ENODEV;
1146
1147 sp = bus_to_subsys(sif->subsys);
1148 if (!sp)
1149 return -EINVAL;
1150
1151 /*
1152 * Reference in sp is now incremented and will be dropped when
1153 * the interface is removed from the bus
1154 */
1155
1156 mutex_lock(&sp->mutex);
1157 list_add_tail(&sif->node, &sp->interfaces);
1158 if (sif->add_dev) {
1159 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1160 while ((dev = subsys_dev_iter_next(&iter)))
1161 sif->add_dev(dev, sif);
1162 subsys_dev_iter_exit(&iter);
1163 }
1164 mutex_unlock(&sp->mutex);
1165
1166 return 0;
1167}
1168EXPORT_SYMBOL_GPL(subsys_interface_register);
1169
1170void subsys_interface_unregister(struct subsys_interface *sif)
1171{
1172 struct subsys_private *sp;
1173 struct subsys_dev_iter iter;
1174 struct device *dev;
1175
1176 if (!sif || !sif->subsys)
1177 return;
1178
1179 sp = bus_to_subsys(sif->subsys);
1180 if (!sp)
1181 return;
1182
1183 mutex_lock(&sp->mutex);
1184 list_del_init(&sif->node);
1185 if (sif->remove_dev) {
1186 subsys_dev_iter_init(&iter, sp, NULL, NULL);
1187 while ((dev = subsys_dev_iter_next(&iter)))
1188 sif->remove_dev(dev, sif);
1189 subsys_dev_iter_exit(&iter);
1190 }
1191 mutex_unlock(&sp->mutex);
1192
1193 /*
1194 * Decrement the reference count twice, once for the bus_to_subsys()
1195 * call in the start of this function, and the second one from the
1196 * reference increment in subsys_interface_register()
1197 */
1198 subsys_put(sp);
1199 subsys_put(sp);
1200}
1201EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1202
1203static void system_root_device_release(struct device *dev)
1204{
1205 kfree(dev);
1206}
1207
1208static int subsys_register(const struct bus_type *subsys,
1209 const struct attribute_group **groups,
1210 struct kobject *parent_of_root)
1211{
1212 struct subsys_private *sp;
1213 struct device *dev;
1214 int err;
1215
1216 err = bus_register(subsys);
1217 if (err < 0)
1218 return err;
1219
1220 sp = bus_to_subsys(subsys);
1221 if (!sp) {
1222 err = -EINVAL;
1223 goto err_sp;
1224 }
1225
1226 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1227 if (!dev) {
1228 err = -ENOMEM;
1229 goto err_dev;
1230 }
1231
1232 err = dev_set_name(dev, "%s", subsys->name);
1233 if (err < 0)
1234 goto err_name;
1235
1236 dev->kobj.parent = parent_of_root;
1237 dev->groups = groups;
1238 dev->release = system_root_device_release;
1239
1240 err = device_register(dev);
1241 if (err < 0)
1242 goto err_dev_reg;
1243
1244 sp->dev_root = dev;
1245 subsys_put(sp);
1246 return 0;
1247
1248err_dev_reg:
1249 put_device(dev);
1250 dev = NULL;
1251err_name:
1252 kfree(dev);
1253err_dev:
1254 subsys_put(sp);
1255err_sp:
1256 bus_unregister(subsys);
1257 return err;
1258}
1259
1260/**
1261 * subsys_system_register - register a subsystem at /sys/devices/system/
1262 * @subsys: system subsystem
1263 * @groups: default attributes for the root device
1264 *
1265 * All 'system' subsystems have a /sys/devices/system/<name> root device
1266 * with the name of the subsystem. The root device can carry subsystem-
1267 * wide attributes. All registered devices are below this single root
1268 * device and are named after the subsystem with a simple enumeration
1269 * number appended. The registered devices are not explicitly named;
1270 * only 'id' in the device needs to be set.
1271 *
1272 * Do not use this interface for anything new, it exists for compatibility
1273 * with bad ideas only. New subsystems should use plain subsystems; and
1274 * add the subsystem-wide attributes should be added to the subsystem
1275 * directory itself and not some create fake root-device placed in
1276 * /sys/devices/system/<name>.
1277 */
1278int subsys_system_register(const struct bus_type *subsys,
1279 const struct attribute_group **groups)
1280{
1281 return subsys_register(subsys, groups, &system_kset->kobj);
1282}
1283EXPORT_SYMBOL_GPL(subsys_system_register);
1284
1285/**
1286 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1287 * @subsys: virtual subsystem
1288 * @groups: default attributes for the root device
1289 *
1290 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1291 * with the name of the subystem. The root device can carry subsystem-wide
1292 * attributes. All registered devices are below this single root device.
1293 * There's no restriction on device naming. This is for kernel software
1294 * constructs which need sysfs interface.
1295 */
1296int subsys_virtual_register(const struct bus_type *subsys,
1297 const struct attribute_group **groups)
1298{
1299 struct kobject *virtual_dir;
1300
1301 virtual_dir = virtual_device_parent();
1302 if (!virtual_dir)
1303 return -ENOMEM;
1304
1305 return subsys_register(subsys, groups, virtual_dir);
1306}
1307EXPORT_SYMBOL_GPL(subsys_virtual_register);
1308
1309/**
1310 * driver_find - locate driver on a bus by its name.
1311 * @name: name of the driver.
1312 * @bus: bus to scan for the driver.
1313 *
1314 * Call kset_find_obj() to iterate over list of drivers on
1315 * a bus to find driver by name. Return driver if found.
1316 *
1317 * This routine provides no locking to prevent the driver it returns
1318 * from being unregistered or unloaded while the caller is using it.
1319 * The caller is responsible for preventing this.
1320 */
1321struct device_driver *driver_find(const char *name, const struct bus_type *bus)
1322{
1323 struct subsys_private *sp = bus_to_subsys(bus);
1324 struct kobject *k;
1325 struct driver_private *priv;
1326
1327 if (!sp)
1328 return NULL;
1329
1330 k = kset_find_obj(sp->drivers_kset, name);
1331 subsys_put(sp);
1332 if (!k)
1333 return NULL;
1334
1335 priv = to_driver(k);
1336
1337 /* Drop reference added by kset_find_obj() */
1338 kobject_put(k);
1339 return priv->driver;
1340}
1341EXPORT_SYMBOL_GPL(driver_find);
1342
1343/*
1344 * Warning, the value could go to "removed" instantly after calling this function, so be very
1345 * careful when calling it...
1346 */
1347bool bus_is_registered(const struct bus_type *bus)
1348{
1349 struct subsys_private *sp = bus_to_subsys(bus);
1350 bool is_initialized = false;
1351
1352 if (sp) {
1353 is_initialized = true;
1354 subsys_put(sp);
1355 }
1356 return is_initialized;
1357}
1358
1359/**
1360 * bus_get_dev_root - return a pointer to the "device root" of a bus
1361 * @bus: bus to return the device root of.
1362 *
1363 * If a bus has a "device root" structure, return it, WITH THE REFERENCE
1364 * COUNT INCREMENTED.
1365 *
1366 * Note, when finished with the device, a call to put_device() is required.
1367 *
1368 * If the device root is not present (or bus is not a valid pointer), NULL
1369 * will be returned.
1370 */
1371struct device *bus_get_dev_root(const struct bus_type *bus)
1372{
1373 struct subsys_private *sp = bus_to_subsys(bus);
1374 struct device *dev_root;
1375
1376 if (!sp)
1377 return NULL;
1378
1379 dev_root = get_device(sp->dev_root);
1380 subsys_put(sp);
1381 return dev_root;
1382}
1383EXPORT_SYMBOL_GPL(bus_get_dev_root);
1384
1385int __init buses_init(void)
1386{
1387 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1388 if (!bus_kset)
1389 return -ENOMEM;
1390
1391 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1392 if (!system_kset) {
1393 /* Do error handling here as devices_init() do */
1394 kset_unregister(bus_kset);
1395 bus_kset = NULL;
1396 pr_err("%s: failed to create and add kset 'bus'\n", __func__);
1397 return -ENOMEM;
1398 }
1399
1400 return 0;
1401}