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 */
25 static 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
39 static int __must_check bus_rescan_devices_helper(struct device *dev,
40 void *data);
41
bus_get(struct bus_type * bus)42 static 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
bus_put(struct bus_type * bus)51 static void bus_put(struct bus_type *bus)
52 {
53 if (bus)
54 kset_put(&bus->p->subsys);
55 }
56
drv_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)57 static 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
drv_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t count)69 static 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
81 static const struct sysfs_ops driver_sysfs_ops = {
82 .show = drv_attr_show,
83 .store = drv_attr_store,
84 };
85
driver_release(struct kobject * kobj)86 static 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
94 static struct kobj_type driver_ktype = {
95 .sysfs_ops = &driver_sysfs_ops,
96 .release = driver_release,
97 };
98
99 /*
100 * sysfs bindings for buses
101 */
bus_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)102 static 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
bus_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t count)114 static 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
126 static const struct sysfs_ops bus_sysfs_ops = {
127 .show = bus_attr_show,
128 .store = bus_attr_store,
129 };
130
bus_create_file(struct bus_type * bus,struct bus_attribute * attr)131 int 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 }
141 EXPORT_SYMBOL_GPL(bus_create_file);
142
bus_remove_file(struct bus_type * bus,struct bus_attribute * attr)143 void 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 }
150 EXPORT_SYMBOL_GPL(bus_remove_file);
151
bus_release(struct kobject * kobj)152 static 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
161 static struct kobj_type bus_ktype = {
162 .sysfs_ops = &bus_sysfs_ops,
163 .release = bus_release,
164 };
165
bus_uevent_filter(struct kset * kset,struct kobject * kobj)166 static 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
175 static const struct kset_uevent_ops bus_uevent_ops = {
176 .filter = bus_uevent_filter,
177 };
178
179 static struct kset *bus_kset;
180
181 /* Manually detach a device from its associated driver. */
unbind_store(struct device_driver * drv,const char * buf,size_t count)182 static 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 }
198 static 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 */
bind_store(struct device_driver * drv,const char * buf,size_t count)205 static 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 }
228 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
229
drivers_autoprobe_show(struct bus_type * bus,char * buf)230 static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
231 {
232 return sysfs_emit(buf, "%d\n", bus->p->drivers_autoprobe);
233 }
234
drivers_autoprobe_store(struct bus_type * bus,const char * buf,size_t count)235 static 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
drivers_probe_store(struct bus_type * bus,const char * buf,size_t count)245 static 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
next_device(struct klist_iter * i)260 static 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 */
bus_for_each_dev(struct bus_type * bus,struct device * start,void * data,int (* fn)(struct device *,void *))292 int 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 }
309 EXPORT_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 */
bus_find_device(struct bus_type * bus,struct device * start,const void * data,int (* match)(struct device * dev,const void * data))326 struct 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 }
344 EXPORT_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 */
subsys_find_device_by_id(struct bus_type * subsys,unsigned int id,struct device * hint)356 struct 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 }
385 EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
386
next_driver(struct klist_iter * i)387 static 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 */
bus_for_each_drv(struct bus_type * bus,struct device_driver * start,void * data,int (* fn)(struct device_driver *,void *))418 int 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 }
435 EXPORT_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 */
bus_add_device(struct device * dev)445 int 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
467 out_subsys:
468 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
469 out_groups:
470 device_remove_groups(dev, bus->dev_groups);
471 out_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 */
bus_probe_device(struct device * dev)482 void 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 */
bus_remove_device(struct device * dev)510 void 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
add_bind_files(struct device_driver * drv)537 static 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
remove_bind_files(struct device_driver * drv)550 static 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
556 static BUS_ATTR_WO(drivers_probe);
557 static BUS_ATTR_RW(drivers_autoprobe);
558
add_probe_files(struct bus_type * bus)559 static 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);
570 out:
571 return retval;
572 }
573
remove_probe_files(struct bus_type * bus)574 static 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
uevent_store(struct device_driver * drv,const char * buf,size_t count)580 static 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 }
588 static DRIVER_ATTR_WO(uevent);
589
590 /**
591 * bus_add_driver - Add a driver to the bus.
592 * @drv: driver.
593 */
bus_add_driver(struct device_driver * drv)594 int 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_add_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
651 out_unregister:
652 kobject_put(&priv->kobj);
653 /* drv->p is freed in driver_release() */
654 drv->p = NULL;
655 out_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 */
bus_remove_driver(struct device_driver * drv)668 void 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 */
bus_rescan_devices_helper(struct device * dev,void * data)686 static 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 */
bus_rescan_devices(struct bus_type * bus)709 int bus_rescan_devices(struct bus_type *bus)
710 {
711 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
712 }
713 EXPORT_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 */
device_reprobe(struct device * dev)724 int device_reprobe(struct device *dev)
725 {
726 if (dev->driver)
727 device_driver_detach(dev);
728 return bus_rescan_devices_helper(dev, NULL);
729 }
730 EXPORT_SYMBOL_GPL(device_reprobe);
731
bus_add_groups(struct bus_type * bus,const struct attribute_group ** groups)732 static int bus_add_groups(struct bus_type *bus,
733 const struct attribute_group **groups)
734 {
735 return sysfs_create_groups(&bus->p->subsys.kobj, groups);
736 }
737
bus_remove_groups(struct bus_type * bus,const struct attribute_group ** groups)738 static void bus_remove_groups(struct bus_type *bus,
739 const struct attribute_group **groups)
740 {
741 sysfs_remove_groups(&bus->p->subsys.kobj, groups);
742 }
743
klist_devices_get(struct klist_node * n)744 static void klist_devices_get(struct klist_node *n)
745 {
746 struct device_private *dev_prv = to_device_private_bus(n);
747 struct device *dev = dev_prv->device;
748
749 get_device(dev);
750 }
751
klist_devices_put(struct klist_node * n)752 static void klist_devices_put(struct klist_node *n)
753 {
754 struct device_private *dev_prv = to_device_private_bus(n);
755 struct device *dev = dev_prv->device;
756
757 put_device(dev);
758 }
759
bus_uevent_store(struct bus_type * bus,const char * buf,size_t count)760 static ssize_t bus_uevent_store(struct bus_type *bus,
761 const char *buf, size_t count)
762 {
763 int rc;
764
765 rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
766 return rc ? rc : count;
767 }
768 /*
769 * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
770 * here, but can not use it as earlier in the file we have
771 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
772 * function name.
773 */
774 static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
775 bus_uevent_store);
776
777 /**
778 * bus_register - register a driver-core subsystem
779 * @bus: bus to register
780 *
781 * Once we have that, we register the bus with the kobject
782 * infrastructure, then register the children subsystems it has:
783 * the devices and drivers that belong to the subsystem.
784 */
bus_register(struct bus_type * bus)785 int bus_register(struct bus_type *bus)
786 {
787 int retval;
788 struct subsys_private *priv;
789 struct lock_class_key *key = &bus->lock_key;
790
791 priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
792 if (!priv)
793 return -ENOMEM;
794
795 priv->bus = bus;
796 bus->p = priv;
797
798 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
799
800 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
801 if (retval)
802 goto out;
803
804 priv->subsys.kobj.kset = bus_kset;
805 priv->subsys.kobj.ktype = &bus_ktype;
806 priv->drivers_autoprobe = 1;
807
808 retval = kset_register(&priv->subsys);
809 if (retval)
810 goto out;
811
812 retval = bus_create_file(bus, &bus_attr_uevent);
813 if (retval)
814 goto bus_uevent_fail;
815
816 priv->devices_kset = kset_create_and_add("devices", NULL,
817 &priv->subsys.kobj);
818 if (!priv->devices_kset) {
819 retval = -ENOMEM;
820 goto bus_devices_fail;
821 }
822
823 priv->drivers_kset = kset_create_and_add("drivers", NULL,
824 &priv->subsys.kobj);
825 if (!priv->drivers_kset) {
826 retval = -ENOMEM;
827 goto bus_drivers_fail;
828 }
829
830 INIT_LIST_HEAD(&priv->interfaces);
831 __mutex_init(&priv->mutex, "subsys mutex", key);
832 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
833 klist_init(&priv->klist_drivers, NULL, NULL);
834
835 retval = add_probe_files(bus);
836 if (retval)
837 goto bus_probe_files_fail;
838
839 retval = bus_add_groups(bus, bus->bus_groups);
840 if (retval)
841 goto bus_groups_fail;
842
843 pr_debug("bus: '%s': registered\n", bus->name);
844 return 0;
845
846 bus_groups_fail:
847 remove_probe_files(bus);
848 bus_probe_files_fail:
849 kset_unregister(bus->p->drivers_kset);
850 bus_drivers_fail:
851 kset_unregister(bus->p->devices_kset);
852 bus_devices_fail:
853 bus_remove_file(bus, &bus_attr_uevent);
854 bus_uevent_fail:
855 kset_unregister(&bus->p->subsys);
856 out:
857 kfree(bus->p);
858 bus->p = NULL;
859 return retval;
860 }
861 EXPORT_SYMBOL_GPL(bus_register);
862
863 /**
864 * bus_unregister - remove a bus from the system
865 * @bus: bus.
866 *
867 * Unregister the child subsystems and the bus itself.
868 * Finally, we call bus_put() to release the refcount
869 */
bus_unregister(struct bus_type * bus)870 void bus_unregister(struct bus_type *bus)
871 {
872 pr_debug("bus: '%s': unregistering\n", bus->name);
873 if (bus->dev_root)
874 device_unregister(bus->dev_root);
875 bus_remove_groups(bus, bus->bus_groups);
876 remove_probe_files(bus);
877 kset_unregister(bus->p->drivers_kset);
878 kset_unregister(bus->p->devices_kset);
879 bus_remove_file(bus, &bus_attr_uevent);
880 kset_unregister(&bus->p->subsys);
881 }
882 EXPORT_SYMBOL_GPL(bus_unregister);
883
bus_register_notifier(struct bus_type * bus,struct notifier_block * nb)884 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
885 {
886 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
887 }
888 EXPORT_SYMBOL_GPL(bus_register_notifier);
889
bus_unregister_notifier(struct bus_type * bus,struct notifier_block * nb)890 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
891 {
892 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
893 }
894 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
895
bus_get_kset(struct bus_type * bus)896 struct kset *bus_get_kset(struct bus_type *bus)
897 {
898 return &bus->p->subsys;
899 }
900 EXPORT_SYMBOL_GPL(bus_get_kset);
901
bus_get_device_klist(struct bus_type * bus)902 struct klist *bus_get_device_klist(struct bus_type *bus)
903 {
904 return &bus->p->klist_devices;
905 }
906 EXPORT_SYMBOL_GPL(bus_get_device_klist);
907
908 /*
909 * Yes, this forcibly breaks the klist abstraction temporarily. It
910 * just wants to sort the klist, not change reference counts and
911 * take/drop locks rapidly in the process. It does all this while
912 * holding the lock for the list, so objects can't otherwise be
913 * added/removed while we're swizzling.
914 */
device_insertion_sort_klist(struct device * a,struct list_head * list,int (* compare)(const struct device * a,const struct device * b))915 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
916 int (*compare)(const struct device *a,
917 const struct device *b))
918 {
919 struct klist_node *n;
920 struct device_private *dev_prv;
921 struct device *b;
922
923 list_for_each_entry(n, list, n_node) {
924 dev_prv = to_device_private_bus(n);
925 b = dev_prv->device;
926 if (compare(a, b) <= 0) {
927 list_move_tail(&a->p->knode_bus.n_node,
928 &b->p->knode_bus.n_node);
929 return;
930 }
931 }
932 list_move_tail(&a->p->knode_bus.n_node, list);
933 }
934
bus_sort_breadthfirst(struct bus_type * bus,int (* compare)(const struct device * a,const struct device * b))935 void bus_sort_breadthfirst(struct bus_type *bus,
936 int (*compare)(const struct device *a,
937 const struct device *b))
938 {
939 LIST_HEAD(sorted_devices);
940 struct klist_node *n, *tmp;
941 struct device_private *dev_prv;
942 struct device *dev;
943 struct klist *device_klist;
944
945 device_klist = bus_get_device_klist(bus);
946
947 spin_lock(&device_klist->k_lock);
948 list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
949 dev_prv = to_device_private_bus(n);
950 dev = dev_prv->device;
951 device_insertion_sort_klist(dev, &sorted_devices, compare);
952 }
953 list_splice(&sorted_devices, &device_klist->k_list);
954 spin_unlock(&device_klist->k_lock);
955 }
956 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
957
958 /**
959 * subsys_dev_iter_init - initialize subsys device iterator
960 * @iter: subsys iterator to initialize
961 * @subsys: the subsys we wanna iterate over
962 * @start: the device to start iterating from, if any
963 * @type: device_type of the devices to iterate over, NULL for all
964 *
965 * Initialize subsys iterator @iter such that it iterates over devices
966 * of @subsys. If @start is set, the list iteration will start there,
967 * otherwise if it is NULL, the iteration starts at the beginning of
968 * the list.
969 */
subsys_dev_iter_init(struct subsys_dev_iter * iter,struct bus_type * subsys,struct device * start,const struct device_type * type)970 void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
971 struct device *start, const struct device_type *type)
972 {
973 struct klist_node *start_knode = NULL;
974
975 if (start)
976 start_knode = &start->p->knode_bus;
977 klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
978 iter->type = type;
979 }
980 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
981
982 /**
983 * subsys_dev_iter_next - iterate to the next device
984 * @iter: subsys iterator to proceed
985 *
986 * Proceed @iter to the next device and return it. Returns NULL if
987 * iteration is complete.
988 *
989 * The returned device is referenced and won't be released till
990 * iterator is proceed to the next device or exited. The caller is
991 * free to do whatever it wants to do with the device including
992 * calling back into subsys code.
993 */
subsys_dev_iter_next(struct subsys_dev_iter * iter)994 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
995 {
996 struct klist_node *knode;
997 struct device *dev;
998
999 for (;;) {
1000 knode = klist_next(&iter->ki);
1001 if (!knode)
1002 return NULL;
1003 dev = to_device_private_bus(knode)->device;
1004 if (!iter->type || iter->type == dev->type)
1005 return dev;
1006 }
1007 }
1008 EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1009
1010 /**
1011 * subsys_dev_iter_exit - finish iteration
1012 * @iter: subsys iterator to finish
1013 *
1014 * Finish an iteration. Always call this function after iteration is
1015 * complete whether the iteration ran till the end or not.
1016 */
subsys_dev_iter_exit(struct subsys_dev_iter * iter)1017 void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1018 {
1019 klist_iter_exit(&iter->ki);
1020 }
1021 EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1022
subsys_interface_register(struct subsys_interface * sif)1023 int subsys_interface_register(struct subsys_interface *sif)
1024 {
1025 struct bus_type *subsys;
1026 struct subsys_dev_iter iter;
1027 struct device *dev;
1028
1029 if (!sif || !sif->subsys)
1030 return -ENODEV;
1031
1032 subsys = bus_get(sif->subsys);
1033 if (!subsys)
1034 return -EINVAL;
1035
1036 mutex_lock(&subsys->p->mutex);
1037 list_add_tail(&sif->node, &subsys->p->interfaces);
1038 if (sif->add_dev) {
1039 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1040 while ((dev = subsys_dev_iter_next(&iter)))
1041 sif->add_dev(dev, sif);
1042 subsys_dev_iter_exit(&iter);
1043 }
1044 mutex_unlock(&subsys->p->mutex);
1045
1046 return 0;
1047 }
1048 EXPORT_SYMBOL_GPL(subsys_interface_register);
1049
subsys_interface_unregister(struct subsys_interface * sif)1050 void subsys_interface_unregister(struct subsys_interface *sif)
1051 {
1052 struct bus_type *subsys;
1053 struct subsys_dev_iter iter;
1054 struct device *dev;
1055
1056 if (!sif || !sif->subsys)
1057 return;
1058
1059 subsys = sif->subsys;
1060
1061 mutex_lock(&subsys->p->mutex);
1062 list_del_init(&sif->node);
1063 if (sif->remove_dev) {
1064 subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1065 while ((dev = subsys_dev_iter_next(&iter)))
1066 sif->remove_dev(dev, sif);
1067 subsys_dev_iter_exit(&iter);
1068 }
1069 mutex_unlock(&subsys->p->mutex);
1070
1071 bus_put(subsys);
1072 }
1073 EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1074
system_root_device_release(struct device * dev)1075 static void system_root_device_release(struct device *dev)
1076 {
1077 kfree(dev);
1078 }
1079
subsys_register(struct bus_type * subsys,const struct attribute_group ** groups,struct kobject * parent_of_root)1080 static int subsys_register(struct bus_type *subsys,
1081 const struct attribute_group **groups,
1082 struct kobject *parent_of_root)
1083 {
1084 struct device *dev;
1085 int err;
1086
1087 err = bus_register(subsys);
1088 if (err < 0)
1089 return err;
1090
1091 dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1092 if (!dev) {
1093 err = -ENOMEM;
1094 goto err_dev;
1095 }
1096
1097 err = dev_set_name(dev, "%s", subsys->name);
1098 if (err < 0)
1099 goto err_name;
1100
1101 dev->kobj.parent = parent_of_root;
1102 dev->groups = groups;
1103 dev->release = system_root_device_release;
1104
1105 err = device_register(dev);
1106 if (err < 0)
1107 goto err_dev_reg;
1108
1109 subsys->dev_root = dev;
1110 return 0;
1111
1112 err_dev_reg:
1113 put_device(dev);
1114 dev = NULL;
1115 err_name:
1116 kfree(dev);
1117 err_dev:
1118 bus_unregister(subsys);
1119 return err;
1120 }
1121
1122 /**
1123 * subsys_system_register - register a subsystem at /sys/devices/system/
1124 * @subsys: system subsystem
1125 * @groups: default attributes for the root device
1126 *
1127 * All 'system' subsystems have a /sys/devices/system/<name> root device
1128 * with the name of the subsystem. The root device can carry subsystem-
1129 * wide attributes. All registered devices are below this single root
1130 * device and are named after the subsystem with a simple enumeration
1131 * number appended. The registered devices are not explicitly named;
1132 * only 'id' in the device needs to be set.
1133 *
1134 * Do not use this interface for anything new, it exists for compatibility
1135 * with bad ideas only. New subsystems should use plain subsystems; and
1136 * add the subsystem-wide attributes should be added to the subsystem
1137 * directory itself and not some create fake root-device placed in
1138 * /sys/devices/system/<name>.
1139 */
subsys_system_register(struct bus_type * subsys,const struct attribute_group ** groups)1140 int subsys_system_register(struct bus_type *subsys,
1141 const struct attribute_group **groups)
1142 {
1143 return subsys_register(subsys, groups, &system_kset->kobj);
1144 }
1145 EXPORT_SYMBOL_GPL(subsys_system_register);
1146
1147 /**
1148 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1149 * @subsys: virtual subsystem
1150 * @groups: default attributes for the root device
1151 *
1152 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1153 * with the name of the subystem. The root device can carry subsystem-wide
1154 * attributes. All registered devices are below this single root device.
1155 * There's no restriction on device naming. This is for kernel software
1156 * constructs which need sysfs interface.
1157 */
subsys_virtual_register(struct bus_type * subsys,const struct attribute_group ** groups)1158 int subsys_virtual_register(struct bus_type *subsys,
1159 const struct attribute_group **groups)
1160 {
1161 struct kobject *virtual_dir;
1162
1163 virtual_dir = virtual_device_parent(NULL);
1164 if (!virtual_dir)
1165 return -ENOMEM;
1166
1167 return subsys_register(subsys, groups, virtual_dir);
1168 }
1169 EXPORT_SYMBOL_GPL(subsys_virtual_register);
1170
buses_init(void)1171 int __init buses_init(void)
1172 {
1173 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1174 if (!bus_kset)
1175 return -ENOMEM;
1176
1177 system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1178 if (!system_kset)
1179 return -ENOMEM;
1180
1181 return 0;
1182 }
1183