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