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