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