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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/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 && dev->driver == NULL && driver_match_device(drv, dev)) {
214 err = device_driver_attach(drv, dev);
215
216 if (err > 0) {
217 /* success */
218 err = count;
219 } else if (err == 0) {
220 /* driver didn't accept device */
221 err = -ENODEV;
222 }
223 }
224 put_device(dev);
225 bus_put(bus);
226 return err;
227}
228static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
229
230static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
231{
232 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
233}
234
235static ssize_t drivers_autoprobe_store(struct bus_type *bus,
236 const char *buf, size_t count)
237{
238 if (buf[0] == '0')
239 bus->p->drivers_autoprobe = 0;
240 else
241 bus->p->drivers_autoprobe = 1;
242 return count;
243}
244
245static ssize_t drivers_probe_store(struct bus_type *bus,
246 const char *buf, size_t count)
247{
248 struct device *dev;
249 int err = -EINVAL;
250
251 dev = bus_find_device_by_name(bus, NULL, buf);
252 if (!dev)
253 return -ENODEV;
254 if (bus_rescan_devices_helper(dev, NULL) == 0)
255 err = count;
256 put_device(dev);
257 return err;
258}
259
260static struct device *next_device(struct klist_iter *i)
261{
262 struct klist_node *n = klist_next(i);
263 struct device *dev = NULL;
264 struct device_private *dev_prv;
265
266 if (n) {
267 dev_prv = to_device_private_bus(n);
268 dev = dev_prv->device;
269 }
270 return dev;
271}
272
273/**
274 * bus_for_each_dev - device iterator.
275 * @bus: bus type.
276 * @start: device to start iterating from.
277 * @data: data for the callback.
278 * @fn: function to be called for each device.
279 *
280 * Iterate over @bus's list of devices, and call @fn for each,
281 * passing it @data. If @start is not NULL, we use that device to
282 * begin iterating from.
283 *
284 * We check the return of @fn each time. If it returns anything
285 * other than 0, we break out and return that value.
286 *
287 * NOTE: The device that returns a non-zero value is not retained
288 * in any way, nor is its refcount incremented. If the caller needs
289 * to retain this data, it should do so, and increment the reference
290 * count in the supplied callback.
291 */
292int bus_for_each_dev(struct bus_type *bus, struct device *start,
293 void *data, int (*fn)(struct device *, void *))
294{
295 struct klist_iter i;
296 struct device *dev;
297 int error = 0;
298
299 if (!bus || !bus->p)
300 return -EINVAL;
301
302 klist_iter_init_node(&bus->p->klist_devices, &i,
303 (start ? &start->p->knode_bus : NULL));
304 while (!error && (dev = next_device(&i)))
305 error = fn(dev, data);
306 klist_iter_exit(&i);
307 return error;
308}
309EXPORT_SYMBOL_GPL(bus_for_each_dev);
310
311/**
312 * bus_find_device - device iterator for locating a particular device.
313 * @bus: bus type
314 * @start: Device to begin with
315 * @data: Data to pass to match function
316 * @match: Callback function to check device
317 *
318 * This is similar to the bus_for_each_dev() function above, but it
319 * returns a reference to a device that is 'found' for later use, as
320 * determined by the @match callback.
321 *
322 * The callback should return 0 if the device doesn't match and non-zero
323 * if it does. If the callback returns non-zero, this function will
324 * return to the caller and not iterate over any more devices.
325 */
326struct device *bus_find_device(struct bus_type *bus,
327 struct device *start, const void *data,
328 int (*match)(struct device *dev, const void *data))
329{
330 struct klist_iter i;
331 struct device *dev;
332
333 if (!bus || !bus->p)
334 return NULL;
335
336 klist_iter_init_node(&bus->p->klist_devices, &i,
337 (start ? &start->p->knode_bus : NULL));
338 while ((dev = next_device(&i)))
339 if (match(dev, data) && get_device(dev))
340 break;
341 klist_iter_exit(&i);
342 return dev;
343}
344EXPORT_SYMBOL_GPL(bus_find_device);
345
346/**
347 * subsys_find_device_by_id - find a device with a specific enumeration number
348 * @subsys: subsystem
349 * @id: index 'id' in struct device
350 * @hint: device to check first
351 *
352 * Check the hint's next object and if it is a match return it directly,
353 * otherwise, fall back to a full list search. Either way a reference for
354 * the returned object is taken.
355 */
356struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
357 struct device *hint)
358{
359 struct klist_iter i;
360 struct device *dev;
361
362 if (!subsys)
363 return NULL;
364
365 if (hint) {
366 klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
367 dev = next_device(&i);
368 if (dev && dev->id == id && get_device(dev)) {
369 klist_iter_exit(&i);
370 return dev;
371 }
372 klist_iter_exit(&i);
373 }
374
375 klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
376 while ((dev = next_device(&i))) {
377 if (dev->id == id && get_device(dev)) {
378 klist_iter_exit(&i);
379 return dev;
380 }
381 }
382 klist_iter_exit(&i);
383 return NULL;
384}
385EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
386
387static struct device_driver *next_driver(struct klist_iter *i)
388{
389 struct klist_node *n = klist_next(i);
390 struct driver_private *drv_priv;
391
392 if (n) {
393 drv_priv = container_of(n, struct driver_private, knode_bus);
394 return drv_priv->driver;
395 }
396 return NULL;
397}
398
399/**
400 * bus_for_each_drv - driver iterator
401 * @bus: bus we're dealing with.
402 * @start: driver to start iterating on.
403 * @data: data to pass to the callback.
404 * @fn: function to call for each driver.
405 *
406 * This is nearly identical to the device iterator above.
407 * We iterate over each driver that belongs to @bus, and call
408 * @fn for each. If @fn returns anything but 0, we break out
409 * and return it. If @start is not NULL, we use it as the head
410 * of the list.
411 *
412 * NOTE: we don't return the driver that returns a non-zero
413 * value, nor do we leave the reference count incremented for that
414 * driver. If the caller needs to know that info, it must set it
415 * in the callback. It must also be sure to increment the refcount
416 * so it doesn't disappear before returning to the caller.
417 */
418int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
419 void *data, int (*fn)(struct device_driver *, void *))
420{
421 struct klist_iter i;
422 struct device_driver *drv;
423 int error = 0;
424
425 if (!bus)
426 return -EINVAL;
427
428 klist_iter_init_node(&bus->p->klist_drivers, &i,
429 start ? &start->p->knode_bus : NULL);
430 while ((drv = next_driver(&i)) && !error)
431 error = fn(drv, data);
432 klist_iter_exit(&i);
433 return error;
434}
435EXPORT_SYMBOL_GPL(bus_for_each_drv);
436
437/**
438 * bus_add_device - add device to bus
439 * @dev: device being added
440 *
441 * - Add device's bus attributes.
442 * - Create links to device's bus.
443 * - Add the device to its bus's list of devices.
444 */
445int bus_add_device(struct device *dev)
446{
447 struct bus_type *bus = bus_get(dev->bus);
448 int error = 0;
449
450 if (bus) {
451 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
452 error = device_add_groups(dev, bus->dev_groups);
453 if (error)
454 goto out_put;
455 error = sysfs_create_link(&bus->p->devices_kset->kobj,
456 &dev->kobj, dev_name(dev));
457 if (error)
458 goto out_groups;
459 error = sysfs_create_link(&dev->kobj,
460 &dev->bus->p->subsys.kobj, "subsystem");
461 if (error)
462 goto out_subsys;
463 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
464 }
465 return 0;
466
467out_subsys:
468 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
469out_groups:
470 device_remove_groups(dev, bus->dev_groups);
471out_put:
472 bus_put(dev->bus);
473 return error;
474}
475
476/**
477 * bus_probe_device - probe drivers for a new device
478 * @dev: device to probe
479 *
480 * - Automatically probe for a driver if the bus allows it.
481 */
482void bus_probe_device(struct device *dev)
483{
484 struct bus_type *bus = dev->bus;
485 struct subsys_interface *sif;
486
487 if (!bus)
488 return;
489
490 if (bus->p->drivers_autoprobe)
491 device_initial_probe(dev);
492
493 mutex_lock(&bus->p->mutex);
494 list_for_each_entry(sif, &bus->p->interfaces, node)
495 if (sif->add_dev)
496 sif->add_dev(dev, sif);
497 mutex_unlock(&bus->p->mutex);
498}
499
500/**
501 * bus_remove_device - remove device from bus
502 * @dev: device to be removed
503 *
504 * - Remove device from all interfaces.
505 * - Remove symlink from bus' directory.
506 * - Delete device from bus's list.
507 * - Detach from its driver.
508 * - Drop reference taken in bus_add_device().
509 */
510void bus_remove_device(struct device *dev)
511{
512 struct bus_type *bus = dev->bus;
513 struct subsys_interface *sif;
514
515 if (!bus)
516 return;
517
518 mutex_lock(&bus->p->mutex);
519 list_for_each_entry(sif, &bus->p->interfaces, node)
520 if (sif->remove_dev)
521 sif->remove_dev(dev, sif);
522 mutex_unlock(&bus->p->mutex);
523
524 sysfs_remove_link(&dev->kobj, "subsystem");
525 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
526 dev_name(dev));
527 device_remove_groups(dev, dev->bus->dev_groups);
528 if (klist_node_attached(&dev->p->knode_bus))
529 klist_del(&dev->p->knode_bus);
530
531 pr_debug("bus: '%s': remove device %s\n",
532 dev->bus->name, dev_name(dev));
533 device_release_driver(dev);
534 bus_put(dev->bus);
535}
536
537static int __must_check add_bind_files(struct device_driver *drv)
538{
539 int ret;
540
541 ret = driver_create_file(drv, &driver_attr_unbind);
542 if (ret == 0) {
543 ret = driver_create_file(drv, &driver_attr_bind);
544 if (ret)
545 driver_remove_file(drv, &driver_attr_unbind);
546 }
547 return ret;
548}
549
550static void remove_bind_files(struct device_driver *drv)
551{
552 driver_remove_file(drv, &driver_attr_bind);
553 driver_remove_file(drv, &driver_attr_unbind);
554}
555
556static BUS_ATTR_WO(drivers_probe);
557static BUS_ATTR_RW(drivers_autoprobe);
558
559static int add_probe_files(struct bus_type *bus)
560{
561 int retval;
562
563 retval = bus_create_file(bus, &bus_attr_drivers_probe);
564 if (retval)
565 goto out;
566
567 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
568 if (retval)
569 bus_remove_file(bus, &bus_attr_drivers_probe);
570out:
571 return retval;
572}
573
574static void remove_probe_files(struct bus_type *bus)
575{
576 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
577 bus_remove_file(bus, &bus_attr_drivers_probe);
578}
579
580static ssize_t uevent_store(struct device_driver *drv, const char *buf,
581 size_t count)
582{
583 int rc;
584
585 rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
586 return rc ? rc : count;
587}
588static DRIVER_ATTR_WO(uevent);
589
590/**
591 * bus_add_driver - Add a driver to the bus.
592 * @drv: driver.
593 */
594int bus_add_driver(struct device_driver *drv)
595{
596 struct bus_type *bus;
597 struct driver_private *priv;
598 int error = 0;
599
600 bus = bus_get(drv->bus);
601 if (!bus)
602 return -EINVAL;
603
604 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
605
606 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
607 if (!priv) {
608 error = -ENOMEM;
609 goto out_put_bus;
610 }
611 klist_init(&priv->klist_devices, NULL, NULL);
612 priv->driver = drv;
613 drv->p = priv;
614 priv->kobj.kset = bus->p->drivers_kset;
615 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
616 "%s", drv->name);
617 if (error)
618 goto out_unregister;
619
620 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
621 if (drv->bus->p->drivers_autoprobe) {
622 error = driver_attach(drv);
623 if (error)
624 goto out_unregister;
625 }
626 module_add_driver(drv->owner, drv);
627
628 error = driver_create_file(drv, &driver_attr_uevent);
629 if (error) {
630 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
631 __func__, drv->name);
632 }
633 error = driver_add_groups(drv, bus->drv_groups);
634 if (error) {
635 /* How the hell do we get out of this pickle? Give up */
636 printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
637 __func__, drv->name);
638 }
639
640 if (!drv->suppress_bind_attrs) {
641 error = add_bind_files(drv);
642 if (error) {
643 /* Ditto */
644 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
645 __func__, drv->name);
646 }
647 }
648
649 return 0;
650
651out_unregister:
652 kobject_put(&priv->kobj);
653 /* drv->p is freed in driver_release() */
654 drv->p = NULL;
655out_put_bus:
656 bus_put(bus);
657 return error;
658}
659
660/**
661 * bus_remove_driver - delete driver from bus's knowledge.
662 * @drv: driver.
663 *
664 * Detach the driver from the devices it controls, and remove
665 * it from its bus's list of drivers. Finally, we drop the reference
666 * to the bus we took in bus_add_driver().
667 */
668void bus_remove_driver(struct device_driver *drv)
669{
670 if (!drv->bus)
671 return;
672
673 if (!drv->suppress_bind_attrs)
674 remove_bind_files(drv);
675 driver_remove_groups(drv, drv->bus->drv_groups);
676 driver_remove_file(drv, &driver_attr_uevent);
677 klist_remove(&drv->p->knode_bus);
678 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
679 driver_detach(drv);
680 module_remove_driver(drv);
681 kobject_put(&drv->p->kobj);
682 bus_put(drv->bus);
683}
684
685/* Helper for bus_rescan_devices's iter */
686static int __must_check bus_rescan_devices_helper(struct device *dev,
687 void *data)
688{
689 int ret = 0;
690
691 if (!dev->driver) {
692 if (dev->parent && dev->bus->need_parent_lock)
693 device_lock(dev->parent);
694 ret = device_attach(dev);
695 if (dev->parent && dev->bus->need_parent_lock)
696 device_unlock(dev->parent);
697 }
698 return ret < 0 ? ret : 0;
699}
700
701/**
702 * bus_rescan_devices - rescan devices on the bus for possible drivers
703 * @bus: the bus to scan.
704 *
705 * This function will look for devices on the bus with no driver
706 * attached and rescan it against existing drivers to see if it matches
707 * any by calling device_attach() for the unbound devices.
708 */
709int bus_rescan_devices(struct bus_type *bus)
710{
711 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
712}
713EXPORT_SYMBOL_GPL(bus_rescan_devices);
714
715/**
716 * device_reprobe - remove driver for a device and probe for a new driver
717 * @dev: the device to reprobe
718 *
719 * This function detaches the attached driver (if any) for the given
720 * device and restarts the driver probing process. It is intended
721 * to use if probing criteria changed during a devices lifetime and
722 * driver attachment should change accordingly.
723 */
724int device_reprobe(struct device *dev)
725{
726 if (dev->driver)
727 device_driver_detach(dev);
728 return bus_rescan_devices_helper(dev, NULL);
729}
730EXPORT_SYMBOL_GPL(device_reprobe);
731
732/**
733 * find_bus - locate bus by name.
734 * @name: name of bus.
735 *
736 * Call kset_find_obj() to iterate over list of buses to
737 * find a bus by name. Return bus if found.
738 *
739 * Note that kset_find_obj increments bus' reference count.
740 */
741#if 0
742struct bus_type *find_bus(char *name)
743{
744 struct kobject *k = kset_find_obj(bus_kset, name);
745 return k ? to_bus(k) : NULL;
746}
747#endif /* 0 */
748
749static int bus_add_groups(struct bus_type *bus,
750 const struct attribute_group **groups)
751{
752 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
753}
754
755static void bus_remove_groups(struct bus_type *bus,
756 const struct attribute_group **groups)
757{
758 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
759}
760
761static void klist_devices_get(struct klist_node *n)
762{
763 struct device_private *dev_prv = to_device_private_bus(n);
764 struct device *dev = dev_prv->device;
765
766 get_device(dev);
767}
768
769static void klist_devices_put(struct klist_node *n)
770{
771 struct device_private *dev_prv = to_device_private_bus(n);
772 struct device *dev = dev_prv->device;
773
774 put_device(dev);
775}
776
777static ssize_t bus_uevent_store(struct bus_type *bus,
778 const char *buf, size_t count)
779{
780 int rc;
781
782 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
783 return rc ? rc : count;
784}
785/*
786 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
787 * here, but can not use it as earlier in the file we have
788 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
789 * function name.
790 */
791static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
792 bus_uevent_store);
793
794/**
795 * bus_register - register a driver-core subsystem
796 * @bus: bus to register
797 *
798 * Once we have that, we register the bus with the kobject
799 * infrastructure, then register the children subsystems it has:
800 * the devices and drivers that belong to the subsystem.
801 */
802int bus_register(struct bus_type *bus)
803{
804 int retval;
805 struct subsys_private *priv;
806 struct lock_class_key *key = &bus->lock_key;
807
808 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
809 if (!priv)
810 return -ENOMEM;
811
812 priv->bus = bus;
813 bus->p = priv;
814
815 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
816
817 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
818 if (retval)
819 goto out;
820
821 priv->subsys.kobj.kset = bus_kset;
822 priv->subsys.kobj.ktype = &bus_ktype;
823 priv->drivers_autoprobe = 1;
824
825 retval = kset_register(&priv->subsys);
826 if (retval)
827 goto out;
828
829 retval = bus_create_file(bus, &bus_attr_uevent);
830 if (retval)
831 goto bus_uevent_fail;
832
833 priv->devices_kset = kset_create_and_add("devices", NULL,
834 &priv->subsys.kobj);
835 if (!priv->devices_kset) {
836 retval = -ENOMEM;
837 goto bus_devices_fail;
838 }
839
840 priv->drivers_kset = kset_create_and_add("drivers", NULL,
841 &priv->subsys.kobj);
842 if (!priv->drivers_kset) {
843 retval = -ENOMEM;
844 goto bus_drivers_fail;
845 }
846
847 INIT_LIST_HEAD(&priv->interfaces);
848 __mutex_init(&priv->mutex, "subsys mutex", key);
849 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
850 klist_init(&priv->klist_drivers, NULL, NULL);
851
852 retval = add_probe_files(bus);
853 if (retval)
854 goto bus_probe_files_fail;
855
856 retval = bus_add_groups(bus, bus->bus_groups);
857 if (retval)
858 goto bus_groups_fail;
859
860 pr_debug("bus: '%s': registered\n", bus->name);
861 return 0;
862
863bus_groups_fail:
864 remove_probe_files(bus);
865bus_probe_files_fail:
866 kset_unregister(bus->p->drivers_kset);
867bus_drivers_fail:
868 kset_unregister(bus->p->devices_kset);
869bus_devices_fail:
870 bus_remove_file(bus, &bus_attr_uevent);
871bus_uevent_fail:
872 kset_unregister(&bus->p->subsys);
873out:
874 kfree(bus->p);
875 bus->p = NULL;
876 return retval;
877}
878EXPORT_SYMBOL_GPL(bus_register);
879
880/**
881 * bus_unregister - remove a bus from the system
882 * @bus: bus.
883 *
884 * Unregister the child subsystems and the bus itself.
885 * Finally, we call bus_put() to release the refcount
886 */
887void bus_unregister(struct bus_type *bus)
888{
889 pr_debug("bus: '%s': unregistering\n", bus->name);
890 if (bus->dev_root)
891 device_unregister(bus->dev_root);
892 bus_remove_groups(bus, bus->bus_groups);
893 remove_probe_files(bus);
894 kset_unregister(bus->p->drivers_kset);
895 kset_unregister(bus->p->devices_kset);
896 bus_remove_file(bus, &bus_attr_uevent);
897 kset_unregister(&bus->p->subsys);
898}
899EXPORT_SYMBOL_GPL(bus_unregister);
900
901int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
902{
903 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
904}
905EXPORT_SYMBOL_GPL(bus_register_notifier);
906
907int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
908{
909 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
910}
911EXPORT_SYMBOL_GPL(bus_unregister_notifier);
912
913struct kset *bus_get_kset(struct bus_type *bus)
914{
915 return &bus->p->subsys;
916}
917EXPORT_SYMBOL_GPL(bus_get_kset);
918
919struct klist *bus_get_device_klist(struct bus_type *bus)
920{
921 return &bus->p->klist_devices;
922}
923EXPORT_SYMBOL_GPL(bus_get_device_klist);
924
925/*
926 * Yes, this forcibly breaks the klist abstraction temporarily. It
927 * just wants to sort the klist, not change reference counts and
928 * take/drop locks rapidly in the process. It does all this while
929 * holding the lock for the list, so objects can't otherwise be
930 * added/removed while we're swizzling.
931 */
932static void device_insertion_sort_klist(struct device *a, struct list_head *list,
933 int (*compare)(const struct device *a,
934 const struct device *b))
935{
936 struct klist_node *n;
937 struct device_private *dev_prv;
938 struct device *b;
939
940 list_for_each_entry(n, list, n_node) {
941 dev_prv = to_device_private_bus(n);
942 b = dev_prv->device;
943 if (compare(a, b) <= 0) {
944 list_move_tail(&a->p->knode_bus.n_node,
945 &b->p->knode_bus.n_node);
946 return;
947 }
948 }
949 list_move_tail(&a->p->knode_bus.n_node, list);
950}
951
952void bus_sort_breadthfirst(struct bus_type *bus,
953 int (*compare)(const struct device *a,
954 const struct device *b))
955{
956 LIST_HEAD(sorted_devices);
957 struct klist_node *n, *tmp;
958 struct device_private *dev_prv;
959 struct device *dev;
960 struct klist *device_klist;
961
962 device_klist = bus_get_device_klist(bus);
963
964 spin_lock(&device_klist->k_lock);
965 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
966 dev_prv = to_device_private_bus(n);
967 dev = dev_prv->device;
968 device_insertion_sort_klist(dev, &sorted_devices, compare);
969 }
970 list_splice(&sorted_devices, &device_klist->k_list);
971 spin_unlock(&device_klist->k_lock);
972}
973EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
974
975/**
976 * subsys_dev_iter_init - initialize subsys device iterator
977 * @iter: subsys iterator to initialize
978 * @subsys: the subsys we wanna iterate over
979 * @start: the device to start iterating from, if any
980 * @type: device_type of the devices to iterate over, NULL for all
981 *
982 * Initialize subsys iterator @iter such that it iterates over devices
983 * of @subsys. If @start is set, the list iteration will start there,
984 * otherwise if it is NULL, the iteration starts at the beginning of
985 * the list.
986 */
987void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
988 struct device *start, const struct device_type *type)
989{
990 struct klist_node *start_knode = NULL;
991
992 if (start)
993 start_knode = &start->p->knode_bus;
994 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
995 iter->type = type;
996}
997EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
998
999/**
1000 * subsys_dev_iter_next - iterate to the next device
1001 * @iter: subsys iterator to proceed
1002 *
1003 * Proceed @iter to the next device and return it. Returns NULL if
1004 * iteration is complete.
1005 *
1006 * The returned device is referenced and won't be released till
1007 * iterator is proceed to the next device or exited. The caller is
1008 * free to do whatever it wants to do with the device including
1009 * calling back into subsys code.
1010 */
1011struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1012{
1013 struct klist_node *knode;
1014 struct device *dev;
1015
1016 for (;;) {
1017 knode = klist_next(&iter->ki);
1018 if (!knode)
1019 return NULL;
1020 dev = to_device_private_bus(knode)->device;
1021 if (!iter->type || iter->type == dev->type)
1022 return dev;
1023 }
1024}
1025EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1026
1027/**
1028 * subsys_dev_iter_exit - finish iteration
1029 * @iter: subsys iterator to finish
1030 *
1031 * Finish an iteration. Always call this function after iteration is
1032 * complete whether the iteration ran till the end or not.
1033 */
1034void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1035{
1036 klist_iter_exit(&iter->ki);
1037}
1038EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1039
1040int subsys_interface_register(struct subsys_interface *sif)
1041{
1042 struct bus_type *subsys;
1043 struct subsys_dev_iter iter;
1044 struct device *dev;
1045
1046 if (!sif || !sif->subsys)
1047 return -ENODEV;
1048
1049 subsys = bus_get(sif->subsys);
1050 if (!subsys)
1051 return -EINVAL;
1052
1053 mutex_lock(&subsys->p->mutex);
1054 list_add_tail(&sif->node, &subsys->p->interfaces);
1055 if (sif->add_dev) {
1056 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1057 while ((dev = subsys_dev_iter_next(&iter)))
1058 sif->add_dev(dev, sif);
1059 subsys_dev_iter_exit(&iter);
1060 }
1061 mutex_unlock(&subsys->p->mutex);
1062
1063 return 0;
1064}
1065EXPORT_SYMBOL_GPL(subsys_interface_register);
1066
1067void subsys_interface_unregister(struct subsys_interface *sif)
1068{
1069 struct bus_type *subsys;
1070 struct subsys_dev_iter iter;
1071 struct device *dev;
1072
1073 if (!sif || !sif->subsys)
1074 return;
1075
1076 subsys = sif->subsys;
1077
1078 mutex_lock(&subsys->p->mutex);
1079 list_del_init(&sif->node);
1080 if (sif->remove_dev) {
1081 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1082 while ((dev = subsys_dev_iter_next(&iter)))
1083 sif->remove_dev(dev, sif);
1084 subsys_dev_iter_exit(&iter);
1085 }
1086 mutex_unlock(&subsys->p->mutex);
1087
1088 bus_put(subsys);
1089}
1090EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1091
1092static void system_root_device_release(struct device *dev)
1093{
1094 kfree(dev);
1095}
1096
1097static int subsys_register(struct bus_type *subsys,
1098 const struct attribute_group **groups,
1099 struct kobject *parent_of_root)
1100{
1101 struct device *dev;
1102 int err;
1103
1104 err = bus_register(subsys);
1105 if (err < 0)
1106 return err;
1107
1108 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1109 if (!dev) {
1110 err = -ENOMEM;
1111 goto err_dev;
1112 }
1113
1114 err = dev_set_name(dev, "%s", subsys->name);
1115 if (err < 0)
1116 goto err_name;
1117
1118 dev->kobj.parent = parent_of_root;
1119 dev->groups = groups;
1120 dev->release = system_root_device_release;
1121
1122 err = device_register(dev);
1123 if (err < 0)
1124 goto err_dev_reg;
1125
1126 subsys->dev_root = dev;
1127 return 0;
1128
1129err_dev_reg:
1130 put_device(dev);
1131 dev = NULL;
1132err_name:
1133 kfree(dev);
1134err_dev:
1135 bus_unregister(subsys);
1136 return err;
1137}
1138
1139/**
1140 * subsys_system_register - register a subsystem at /sys/devices/system/
1141 * @subsys: system subsystem
1142 * @groups: default attributes for the root device
1143 *
1144 * All 'system' subsystems have a /sys/devices/system/<name> root device
1145 * with the name of the subsystem. The root device can carry subsystem-
1146 * wide attributes. All registered devices are below this single root
1147 * device and are named after the subsystem with a simple enumeration
1148 * number appended. The registered devices are not explicitly named;
1149 * only 'id' in the device needs to be set.
1150 *
1151 * Do not use this interface for anything new, it exists for compatibility
1152 * with bad ideas only. New subsystems should use plain subsystems; and
1153 * add the subsystem-wide attributes should be added to the subsystem
1154 * directory itself and not some create fake root-device placed in
1155 * /sys/devices/system/<name>.
1156 */
1157int subsys_system_register(struct bus_type *subsys,
1158 const struct attribute_group **groups)
1159{
1160 return subsys_register(subsys, groups, &system_kset->kobj);
1161}
1162EXPORT_SYMBOL_GPL(subsys_system_register);
1163
1164/**
1165 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1166 * @subsys: virtual subsystem
1167 * @groups: default attributes for the root device
1168 *
1169 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1170 * with the name of the subystem. The root device can carry subsystem-wide
1171 * attributes. All registered devices are below this single root device.
1172 * There's no restriction on device naming. This is for kernel software
1173 * constructs which need sysfs interface.
1174 */
1175int subsys_virtual_register(struct bus_type *subsys,
1176 const struct attribute_group **groups)
1177{
1178 struct kobject *virtual_dir;
1179
1180 virtual_dir = virtual_device_parent(NULL);
1181 if (!virtual_dir)
1182 return -ENOMEM;
1183
1184 return subsys_register(subsys, groups, virtual_dir);
1185}
1186EXPORT_SYMBOL_GPL(subsys_virtual_register);
1187
1188int __init buses_init(void)
1189{
1190 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1191 if (!bus_kset)
1192 return -ENOMEM;
1193
1194 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1195 if (!system_kset)
1196 return -ENOMEM;
1197
1198 return 0;
1199}