Root/drivers/base/bus.c

1/*
2 * bus.c - bus driver management
3 *
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
6 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
7 * Copyright (c) 2007 Novell Inc.
8 *
9 * This file is released under the GPLv2
10 *
11 */
12
13#include <linux/device.h>
14#include <linux/module.h>
15#include <linux/errno.h>
16#include <linux/slab.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/mutex.h>
20#include "base.h"
21#include "power/power.h"
22
23/* /sys/devices/system */
24static struct kset *system_kset;
25
26#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
27
28/*
29 * sysfs bindings for drivers
30 */
31
32#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
33
34
35static int __must_check bus_rescan_devices_helper(struct device *dev,
36                        void *data);
37
38static struct bus_type *bus_get(struct bus_type *bus)
39{
40    if (bus) {
41        kset_get(&bus->p->subsys);
42        return bus;
43    }
44    return NULL;
45}
46
47static void bus_put(struct bus_type *bus)
48{
49    if (bus)
50        kset_put(&bus->p->subsys);
51}
52
53static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
54                 char *buf)
55{
56    struct driver_attribute *drv_attr = to_drv_attr(attr);
57    struct driver_private *drv_priv = to_driver(kobj);
58    ssize_t ret = -EIO;
59
60    if (drv_attr->show)
61        ret = drv_attr->show(drv_priv->driver, buf);
62    return ret;
63}
64
65static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
66                  const char *buf, size_t count)
67{
68    struct driver_attribute *drv_attr = to_drv_attr(attr);
69    struct driver_private *drv_priv = to_driver(kobj);
70    ssize_t ret = -EIO;
71
72    if (drv_attr->store)
73        ret = drv_attr->store(drv_priv->driver, buf, count);
74    return ret;
75}
76
77static const struct sysfs_ops driver_sysfs_ops = {
78    .show = drv_attr_show,
79    .store = drv_attr_store,
80};
81
82static void driver_release(struct kobject *kobj)
83{
84    struct driver_private *drv_priv = to_driver(kobj);
85
86    pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
87    kfree(drv_priv);
88}
89
90static struct kobj_type driver_ktype = {
91    .sysfs_ops = &driver_sysfs_ops,
92    .release = driver_release,
93};
94
95/*
96 * sysfs bindings for buses
97 */
98static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
99                 char *buf)
100{
101    struct bus_attribute *bus_attr = to_bus_attr(attr);
102    struct subsys_private *subsys_priv = to_subsys_private(kobj);
103    ssize_t ret = 0;
104
105    if (bus_attr->show)
106        ret = bus_attr->show(subsys_priv->bus, buf);
107    return ret;
108}
109
110static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
111                  const char *buf, size_t count)
112{
113    struct bus_attribute *bus_attr = to_bus_attr(attr);
114    struct subsys_private *subsys_priv = to_subsys_private(kobj);
115    ssize_t ret = 0;
116
117    if (bus_attr->store)
118        ret = bus_attr->store(subsys_priv->bus, buf, count);
119    return ret;
120}
121
122static const struct sysfs_ops bus_sysfs_ops = {
123    .show = bus_attr_show,
124    .store = bus_attr_store,
125};
126
127int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
128{
129    int error;
130    if (bus_get(bus)) {
131        error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
132        bus_put(bus);
133    } else
134        error = -EINVAL;
135    return error;
136}
137EXPORT_SYMBOL_GPL(bus_create_file);
138
139void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
140{
141    if (bus_get(bus)) {
142        sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
143        bus_put(bus);
144    }
145}
146EXPORT_SYMBOL_GPL(bus_remove_file);
147
148static struct kobj_type bus_ktype = {
149    .sysfs_ops = &bus_sysfs_ops,
150};
151
152static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
153{
154    struct kobj_type *ktype = get_ktype(kobj);
155
156    if (ktype == &bus_ktype)
157        return 1;
158    return 0;
159}
160
161static const struct kset_uevent_ops bus_uevent_ops = {
162    .filter = bus_uevent_filter,
163};
164
165static struct kset *bus_kset;
166
167/* Manually detach a device from its associated driver. */
168static ssize_t driver_unbind(struct device_driver *drv,
169                 const char *buf, size_t count)
170{
171    struct bus_type *bus = bus_get(drv->bus);
172    struct device *dev;
173    int err = -ENODEV;
174
175    dev = bus_find_device_by_name(bus, NULL, buf);
176    if (dev && dev->driver == drv) {
177        if (dev->parent) /* Needed for USB */
178            device_lock(dev->parent);
179        device_release_driver(dev);
180        if (dev->parent)
181            device_unlock(dev->parent);
182        err = count;
183    }
184    put_device(dev);
185    bus_put(bus);
186    return err;
187}
188static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
189
190/*
191 * Manually attach a device to a driver.
192 * Note: the driver must want to bind to the device,
193 * it is not possible to override the driver's id table.
194 */
195static ssize_t driver_bind(struct device_driver *drv,
196               const char *buf, size_t count)
197{
198    struct bus_type *bus = bus_get(drv->bus);
199    struct device *dev;
200    int err = -ENODEV;
201
202    dev = bus_find_device_by_name(bus, NULL, buf);
203    if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
204        if (dev->parent) /* Needed for USB */
205            device_lock(dev->parent);
206        device_lock(dev);
207        err = driver_probe_device(drv, dev);
208        device_unlock(dev);
209        if (dev->parent)
210            device_unlock(dev->parent);
211
212        if (err > 0) {
213            /* success */
214            err = count;
215        } else if (err == 0) {
216            /* driver didn't accept device */
217            err = -ENODEV;
218        }
219    }
220    put_device(dev);
221    bus_put(bus);
222    return err;
223}
224static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
225
226static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
227{
228    return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
229}
230
231static ssize_t store_drivers_autoprobe(struct bus_type *bus,
232                       const char *buf, size_t count)
233{
234    if (buf[0] == '0')
235        bus->p->drivers_autoprobe = 0;
236    else
237        bus->p->drivers_autoprobe = 1;
238    return count;
239}
240
241static ssize_t store_drivers_probe(struct bus_type *bus,
242                   const char *buf, size_t count)
243{
244    struct device *dev;
245
246    dev = bus_find_device_by_name(bus, NULL, buf);
247    if (!dev)
248        return -ENODEV;
249    if (bus_rescan_devices_helper(dev, NULL) != 0)
250        return -EINVAL;
251    return count;
252}
253
254static struct device *next_device(struct klist_iter *i)
255{
256    struct klist_node *n = klist_next(i);
257    struct device *dev = NULL;
258    struct device_private *dev_prv;
259
260    if (n) {
261        dev_prv = to_device_private_bus(n);
262        dev = dev_prv->device;
263    }
264    return dev;
265}
266
267/**
268 * bus_for_each_dev - device iterator.
269 * @bus: bus type.
270 * @start: device to start iterating from.
271 * @data: data for the callback.
272 * @fn: function to be called for each device.
273 *
274 * Iterate over @bus's list of devices, and call @fn for each,
275 * passing it @data. If @start is not NULL, we use that device to
276 * begin iterating from.
277 *
278 * We check the return of @fn each time. If it returns anything
279 * other than 0, we break out and return that value.
280 *
281 * NOTE: The device that returns a non-zero value is not retained
282 * in any way, nor is its refcount incremented. If the caller needs
283 * to retain this data, it should do so, and increment the reference
284 * count in the supplied callback.
285 */
286int bus_for_each_dev(struct bus_type *bus, struct device *start,
287             void *data, int (*fn)(struct device *, void *))
288{
289    struct klist_iter i;
290    struct device *dev;
291    int error = 0;
292
293    if (!bus || !bus->p)
294        return -EINVAL;
295
296    klist_iter_init_node(&bus->p->klist_devices, &i,
297                 (start ? &start->p->knode_bus : NULL));
298    while ((dev = next_device(&i)) && !error)
299        error = fn(dev, data);
300    klist_iter_exit(&i);
301    return error;
302}
303EXPORT_SYMBOL_GPL(bus_for_each_dev);
304
305/**
306 * bus_find_device - device iterator for locating a particular device.
307 * @bus: bus type
308 * @start: Device to begin with
309 * @data: Data to pass to match function
310 * @match: Callback function to check device
311 *
312 * This is similar to the bus_for_each_dev() function above, but it
313 * returns a reference to a device that is 'found' for later use, as
314 * determined by the @match callback.
315 *
316 * The callback should return 0 if the device doesn't match and non-zero
317 * if it does. If the callback returns non-zero, this function will
318 * return to the caller and not iterate over any more devices.
319 */
320struct device *bus_find_device(struct bus_type *bus,
321                   struct device *start, void *data,
322                   int (*match)(struct device *dev, void *data))
323{
324    struct klist_iter i;
325    struct device *dev;
326
327    if (!bus || !bus->p)
328        return NULL;
329
330    klist_iter_init_node(&bus->p->klist_devices, &i,
331                 (start ? &start->p->knode_bus : NULL));
332    while ((dev = next_device(&i)))
333        if (match(dev, data) && get_device(dev))
334            break;
335    klist_iter_exit(&i);
336    return dev;
337}
338EXPORT_SYMBOL_GPL(bus_find_device);
339
340static int match_name(struct device *dev, void *data)
341{
342    const char *name = data;
343
344    return sysfs_streq(name, dev_name(dev));
345}
346
347/**
348 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
349 * @bus: bus type
350 * @start: Device to begin with
351 * @name: name of the device to match
352 *
353 * This is similar to the bus_find_device() function above, but it handles
354 * searching by a name automatically, no need to write another strcmp matching
355 * function.
356 */
357struct device *bus_find_device_by_name(struct bus_type *bus,
358                       struct device *start, const char *name)
359{
360    return bus_find_device(bus, start, (void *)name, match_name);
361}
362EXPORT_SYMBOL_GPL(bus_find_device_by_name);
363
364/**
365 * subsys_find_device_by_id - find a device with a specific enumeration number
366 * @subsys: subsystem
367 * @id: index 'id' in struct device
368 * @hint: device to check first
369 *
370 * Check the hint's next object and if it is a match return it directly,
371 * otherwise, fall back to a full list search. Either way a reference for
372 * the returned object is taken.
373 */
374struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
375                    struct device *hint)
376{
377    struct klist_iter i;
378    struct device *dev;
379
380    if (!subsys)
381        return NULL;
382
383    if (hint) {
384        klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
385        dev = next_device(&i);
386        if (dev && dev->id == id && get_device(dev)) {
387            klist_iter_exit(&i);
388            return dev;
389        }
390        klist_iter_exit(&i);
391    }
392
393    klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
394    while ((dev = next_device(&i))) {
395        if (dev->id == id && get_device(dev)) {
396            klist_iter_exit(&i);
397            return dev;
398        }
399    }
400    klist_iter_exit(&i);
401    return NULL;
402}
403EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
404
405static struct device_driver *next_driver(struct klist_iter *i)
406{
407    struct klist_node *n = klist_next(i);
408    struct driver_private *drv_priv;
409
410    if (n) {
411        drv_priv = container_of(n, struct driver_private, knode_bus);
412        return drv_priv->driver;
413    }
414    return NULL;
415}
416
417/**
418 * bus_for_each_drv - driver iterator
419 * @bus: bus we're dealing with.
420 * @start: driver to start iterating on.
421 * @data: data to pass to the callback.
422 * @fn: function to call for each driver.
423 *
424 * This is nearly identical to the device iterator above.
425 * We iterate over each driver that belongs to @bus, and call
426 * @fn for each. If @fn returns anything but 0, we break out
427 * and return it. If @start is not NULL, we use it as the head
428 * of the list.
429 *
430 * NOTE: we don't return the driver that returns a non-zero
431 * value, nor do we leave the reference count incremented for that
432 * driver. If the caller needs to know that info, it must set it
433 * in the callback. It must also be sure to increment the refcount
434 * so it doesn't disappear before returning to the caller.
435 */
436int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
437             void *data, int (*fn)(struct device_driver *, void *))
438{
439    struct klist_iter i;
440    struct device_driver *drv;
441    int error = 0;
442
443    if (!bus)
444        return -EINVAL;
445
446    klist_iter_init_node(&bus->p->klist_drivers, &i,
447                 start ? &start->p->knode_bus : NULL);
448    while ((drv = next_driver(&i)) && !error)
449        error = fn(drv, data);
450    klist_iter_exit(&i);
451    return error;
452}
453EXPORT_SYMBOL_GPL(bus_for_each_drv);
454
455static int device_add_attrs(struct bus_type *bus, struct device *dev)
456{
457    int error = 0;
458    int i;
459
460    if (!bus->dev_attrs)
461        return 0;
462
463    for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
464        error = device_create_file(dev, &bus->dev_attrs[i]);
465        if (error) {
466            while (--i >= 0)
467                device_remove_file(dev, &bus->dev_attrs[i]);
468            break;
469        }
470    }
471    return error;
472}
473
474static void device_remove_attrs(struct bus_type *bus, struct device *dev)
475{
476    int i;
477
478    if (bus->dev_attrs) {
479        for (i = 0; attr_name(bus->dev_attrs[i]); i++)
480            device_remove_file(dev, &bus->dev_attrs[i]);
481    }
482}
483
484/**
485 * bus_add_device - add device to bus
486 * @dev: device being added
487 *
488 * - Add device's bus attributes.
489 * - Create links to device's bus.
490 * - Add the device to its bus's list of devices.
491 */
492int bus_add_device(struct device *dev)
493{
494    struct bus_type *bus = bus_get(dev->bus);
495    int error = 0;
496
497    if (bus) {
498        pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
499        error = device_add_attrs(bus, dev);
500        if (error)
501            goto out_put;
502        error = sysfs_create_link(&bus->p->devices_kset->kobj,
503                        &dev->kobj, dev_name(dev));
504        if (error)
505            goto out_id;
506        error = sysfs_create_link(&dev->kobj,
507                &dev->bus->p->subsys.kobj, "subsystem");
508        if (error)
509            goto out_subsys;
510        klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
511    }
512    return 0;
513
514out_subsys:
515    sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
516out_id:
517    device_remove_attrs(bus, dev);
518out_put:
519    bus_put(dev->bus);
520    return error;
521}
522
523/**
524 * bus_probe_device - probe drivers for a new device
525 * @dev: device to probe
526 *
527 * - Automatically probe for a driver if the bus allows it.
528 */
529void bus_probe_device(struct device *dev)
530{
531    struct bus_type *bus = dev->bus;
532    struct subsys_interface *sif;
533    int ret;
534
535    if (!bus)
536        return;
537
538    if (bus->p->drivers_autoprobe) {
539        ret = device_attach(dev);
540        WARN_ON(ret < 0);
541    }
542
543    mutex_lock(&bus->p->mutex);
544    list_for_each_entry(sif, &bus->p->interfaces, node)
545        if (sif->add_dev)
546            sif->add_dev(dev, sif);
547    mutex_unlock(&bus->p->mutex);
548}
549
550/**
551 * bus_remove_device - remove device from bus
552 * @dev: device to be removed
553 *
554 * - Remove device from all interfaces.
555 * - Remove symlink from bus' directory.
556 * - Delete device from bus's list.
557 * - Detach from its driver.
558 * - Drop reference taken in bus_add_device().
559 */
560void bus_remove_device(struct device *dev)
561{
562    struct bus_type *bus = dev->bus;
563    struct subsys_interface *sif;
564
565    if (!bus)
566        return;
567
568    mutex_lock(&bus->p->mutex);
569    list_for_each_entry(sif, &bus->p->interfaces, node)
570        if (sif->remove_dev)
571            sif->remove_dev(dev, sif);
572    mutex_unlock(&bus->p->mutex);
573
574    sysfs_remove_link(&dev->kobj, "subsystem");
575    sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
576              dev_name(dev));
577    device_remove_attrs(dev->bus, dev);
578    if (klist_node_attached(&dev->p->knode_bus))
579        klist_del(&dev->p->knode_bus);
580
581    pr_debug("bus: '%s': remove device %s\n",
582         dev->bus->name, dev_name(dev));
583    device_release_driver(dev);
584    bus_put(dev->bus);
585}
586
587static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
588{
589    int error = 0;
590    int i;
591
592    if (bus->drv_attrs) {
593        for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
594            error = driver_create_file(drv, &bus->drv_attrs[i]);
595            if (error)
596                goto err;
597        }
598    }
599done:
600    return error;
601err:
602    while (--i >= 0)
603        driver_remove_file(drv, &bus->drv_attrs[i]);
604    goto done;
605}
606
607static void driver_remove_attrs(struct bus_type *bus,
608                struct device_driver *drv)
609{
610    int i;
611
612    if (bus->drv_attrs) {
613        for (i = 0; attr_name(bus->drv_attrs[i]); i++)
614            driver_remove_file(drv, &bus->drv_attrs[i]);
615    }
616}
617
618static int __must_check add_bind_files(struct device_driver *drv)
619{
620    int ret;
621
622    ret = driver_create_file(drv, &driver_attr_unbind);
623    if (ret == 0) {
624        ret = driver_create_file(drv, &driver_attr_bind);
625        if (ret)
626            driver_remove_file(drv, &driver_attr_unbind);
627    }
628    return ret;
629}
630
631static void remove_bind_files(struct device_driver *drv)
632{
633    driver_remove_file(drv, &driver_attr_bind);
634    driver_remove_file(drv, &driver_attr_unbind);
635}
636
637static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
638static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
639        show_drivers_autoprobe, store_drivers_autoprobe);
640
641static int add_probe_files(struct bus_type *bus)
642{
643    int retval;
644
645    retval = bus_create_file(bus, &bus_attr_drivers_probe);
646    if (retval)
647        goto out;
648
649    retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
650    if (retval)
651        bus_remove_file(bus, &bus_attr_drivers_probe);
652out:
653    return retval;
654}
655
656static void remove_probe_files(struct bus_type *bus)
657{
658    bus_remove_file(bus, &bus_attr_drivers_autoprobe);
659    bus_remove_file(bus, &bus_attr_drivers_probe);
660}
661
662static ssize_t driver_uevent_store(struct device_driver *drv,
663                   const char *buf, size_t count)
664{
665    enum kobject_action action;
666
667    if (kobject_action_type(buf, count, &action) == 0)
668        kobject_uevent(&drv->p->kobj, action);
669    return count;
670}
671static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
672
673/**
674 * bus_add_driver - Add a driver to the bus.
675 * @drv: driver.
676 */
677int bus_add_driver(struct device_driver *drv)
678{
679    struct bus_type *bus;
680    struct driver_private *priv;
681    int error = 0;
682
683    bus = bus_get(drv->bus);
684    if (!bus)
685        return -EINVAL;
686
687    pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
688
689    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
690    if (!priv) {
691        error = -ENOMEM;
692        goto out_put_bus;
693    }
694    klist_init(&priv->klist_devices, NULL, NULL);
695    priv->driver = drv;
696    drv->p = priv;
697    priv->kobj.kset = bus->p->drivers_kset;
698    error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
699                     "%s", drv->name);
700    if (error)
701        goto out_unregister;
702
703    klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
704    if (drv->bus->p->drivers_autoprobe) {
705        error = driver_attach(drv);
706        if (error)
707            goto out_unregister;
708    }
709    module_add_driver(drv->owner, drv);
710
711    error = driver_create_file(drv, &driver_attr_uevent);
712    if (error) {
713        printk(KERN_ERR "%s: uevent attr (%s) failed\n",
714            __func__, drv->name);
715    }
716    error = driver_add_attrs(bus, drv);
717    if (error) {
718        /* How the hell do we get out of this pickle? Give up */
719        printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
720            __func__, drv->name);
721    }
722
723    if (!drv->suppress_bind_attrs) {
724        error = add_bind_files(drv);
725        if (error) {
726            /* Ditto */
727            printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
728                __func__, drv->name);
729        }
730    }
731
732    return 0;
733
734out_unregister:
735    kobject_put(&priv->kobj);
736    kfree(drv->p);
737    drv->p = NULL;
738out_put_bus:
739    bus_put(bus);
740    return error;
741}
742
743/**
744 * bus_remove_driver - delete driver from bus's knowledge.
745 * @drv: driver.
746 *
747 * Detach the driver from the devices it controls, and remove
748 * it from its bus's list of drivers. Finally, we drop the reference
749 * to the bus we took in bus_add_driver().
750 */
751void bus_remove_driver(struct device_driver *drv)
752{
753    if (!drv->bus)
754        return;
755
756    if (!drv->suppress_bind_attrs)
757        remove_bind_files(drv);
758    driver_remove_attrs(drv->bus, drv);
759    driver_remove_file(drv, &driver_attr_uevent);
760    klist_remove(&drv->p->knode_bus);
761    pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
762    driver_detach(drv);
763    module_remove_driver(drv);
764    kobject_put(&drv->p->kobj);
765    bus_put(drv->bus);
766}
767
768/* Helper for bus_rescan_devices's iter */
769static int __must_check bus_rescan_devices_helper(struct device *dev,
770                          void *data)
771{
772    int ret = 0;
773
774    if (!dev->driver) {
775        if (dev->parent) /* Needed for USB */
776            device_lock(dev->parent);
777        ret = device_attach(dev);
778        if (dev->parent)
779            device_unlock(dev->parent);
780    }
781    return ret < 0 ? ret : 0;
782}
783
784/**
785 * bus_rescan_devices - rescan devices on the bus for possible drivers
786 * @bus: the bus to scan.
787 *
788 * This function will look for devices on the bus with no driver
789 * attached and rescan it against existing drivers to see if it matches
790 * any by calling device_attach() for the unbound devices.
791 */
792int bus_rescan_devices(struct bus_type *bus)
793{
794    return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
795}
796EXPORT_SYMBOL_GPL(bus_rescan_devices);
797
798/**
799 * device_reprobe - remove driver for a device and probe for a new driver
800 * @dev: the device to reprobe
801 *
802 * This function detaches the attached driver (if any) for the given
803 * device and restarts the driver probing process. It is intended
804 * to use if probing criteria changed during a devices lifetime and
805 * driver attachment should change accordingly.
806 */
807int device_reprobe(struct device *dev)
808{
809    if (dev->driver) {
810        if (dev->parent) /* Needed for USB */
811            device_lock(dev->parent);
812        device_release_driver(dev);
813        if (dev->parent)
814            device_unlock(dev->parent);
815    }
816    return bus_rescan_devices_helper(dev, NULL);
817}
818EXPORT_SYMBOL_GPL(device_reprobe);
819
820/**
821 * find_bus - locate bus by name.
822 * @name: name of bus.
823 *
824 * Call kset_find_obj() to iterate over list of buses to
825 * find a bus by name. Return bus if found.
826 *
827 * Note that kset_find_obj increments bus' reference count.
828 */
829#if 0
830struct bus_type *find_bus(char *name)
831{
832    struct kobject *k = kset_find_obj(bus_kset, name);
833    return k ? to_bus(k) : NULL;
834}
835#endif /* 0 */
836
837
838/**
839 * bus_add_attrs - Add default attributes for this bus.
840 * @bus: Bus that has just been registered.
841 */
842
843static int bus_add_attrs(struct bus_type *bus)
844{
845    int error = 0;
846    int i;
847
848    if (bus->bus_attrs) {
849        for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
850            error = bus_create_file(bus, &bus->bus_attrs[i]);
851            if (error)
852                goto err;
853        }
854    }
855done:
856    return error;
857err:
858    while (--i >= 0)
859        bus_remove_file(bus, &bus->bus_attrs[i]);
860    goto done;
861}
862
863static void bus_remove_attrs(struct bus_type *bus)
864{
865    int i;
866
867    if (bus->bus_attrs) {
868        for (i = 0; attr_name(bus->bus_attrs[i]); i++)
869            bus_remove_file(bus, &bus->bus_attrs[i]);
870    }
871}
872
873static void klist_devices_get(struct klist_node *n)
874{
875    struct device_private *dev_prv = to_device_private_bus(n);
876    struct device *dev = dev_prv->device;
877
878    get_device(dev);
879}
880
881static void klist_devices_put(struct klist_node *n)
882{
883    struct device_private *dev_prv = to_device_private_bus(n);
884    struct device *dev = dev_prv->device;
885
886    put_device(dev);
887}
888
889static ssize_t bus_uevent_store(struct bus_type *bus,
890                const char *buf, size_t count)
891{
892    enum kobject_action action;
893
894    if (kobject_action_type(buf, count, &action) == 0)
895        kobject_uevent(&bus->p->subsys.kobj, action);
896    return count;
897}
898static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
899
900/**
901 * __bus_register - register a driver-core subsystem
902 * @bus: bus to register
903 * @key: lockdep class key
904 *
905 * Once we have that, we register the bus with the kobject
906 * infrastructure, then register the children subsystems it has:
907 * the devices and drivers that belong to the subsystem.
908 */
909int __bus_register(struct bus_type *bus, struct lock_class_key *key)
910{
911    int retval;
912    struct subsys_private *priv;
913
914    priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
915    if (!priv)
916        return -ENOMEM;
917
918    priv->bus = bus;
919    bus->p = priv;
920
921    BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
922
923    retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
924    if (retval)
925        goto out;
926
927    priv->subsys.kobj.kset = bus_kset;
928    priv->subsys.kobj.ktype = &bus_ktype;
929    priv->drivers_autoprobe = 1;
930
931    retval = kset_register(&priv->subsys);
932    if (retval)
933        goto out;
934
935    retval = bus_create_file(bus, &bus_attr_uevent);
936    if (retval)
937        goto bus_uevent_fail;
938
939    priv->devices_kset = kset_create_and_add("devices", NULL,
940                         &priv->subsys.kobj);
941    if (!priv->devices_kset) {
942        retval = -ENOMEM;
943        goto bus_devices_fail;
944    }
945
946    priv->drivers_kset = kset_create_and_add("drivers", NULL,
947                         &priv->subsys.kobj);
948    if (!priv->drivers_kset) {
949        retval = -ENOMEM;
950        goto bus_drivers_fail;
951    }
952
953    INIT_LIST_HEAD(&priv->interfaces);
954    __mutex_init(&priv->mutex, "subsys mutex", key);
955    klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
956    klist_init(&priv->klist_drivers, NULL, NULL);
957
958    retval = add_probe_files(bus);
959    if (retval)
960        goto bus_probe_files_fail;
961
962    retval = bus_add_attrs(bus);
963    if (retval)
964        goto bus_attrs_fail;
965
966    pr_debug("bus: '%s': registered\n", bus->name);
967    return 0;
968
969bus_attrs_fail:
970    remove_probe_files(bus);
971bus_probe_files_fail:
972    kset_unregister(bus->p->drivers_kset);
973bus_drivers_fail:
974    kset_unregister(bus->p->devices_kset);
975bus_devices_fail:
976    bus_remove_file(bus, &bus_attr_uevent);
977bus_uevent_fail:
978    kset_unregister(&bus->p->subsys);
979out:
980    kfree(bus->p);
981    bus->p = NULL;
982    return retval;
983}
984EXPORT_SYMBOL_GPL(__bus_register);
985
986/**
987 * bus_unregister - remove a bus from the system
988 * @bus: bus.
989 *
990 * Unregister the child subsystems and the bus itself.
991 * Finally, we call bus_put() to release the refcount
992 */
993void bus_unregister(struct bus_type *bus)
994{
995    pr_debug("bus: '%s': unregistering\n", bus->name);
996    if (bus->dev_root)
997        device_unregister(bus->dev_root);
998    bus_remove_attrs(bus);
999    remove_probe_files(bus);
1000    kset_unregister(bus->p->drivers_kset);
1001    kset_unregister(bus->p->devices_kset);
1002    bus_remove_file(bus, &bus_attr_uevent);
1003    kset_unregister(&bus->p->subsys);
1004    kfree(bus->p);
1005    bus->p = NULL;
1006}
1007EXPORT_SYMBOL_GPL(bus_unregister);
1008
1009int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
1010{
1011    return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
1012}
1013EXPORT_SYMBOL_GPL(bus_register_notifier);
1014
1015int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
1016{
1017    return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
1018}
1019EXPORT_SYMBOL_GPL(bus_unregister_notifier);
1020
1021struct kset *bus_get_kset(struct bus_type *bus)
1022{
1023    return &bus->p->subsys;
1024}
1025EXPORT_SYMBOL_GPL(bus_get_kset);
1026
1027struct klist *bus_get_device_klist(struct bus_type *bus)
1028{
1029    return &bus->p->klist_devices;
1030}
1031EXPORT_SYMBOL_GPL(bus_get_device_klist);
1032
1033/*
1034 * Yes, this forcibly breaks the klist abstraction temporarily. It
1035 * just wants to sort the klist, not change reference counts and
1036 * take/drop locks rapidly in the process. It does all this while
1037 * holding the lock for the list, so objects can't otherwise be
1038 * added/removed while we're swizzling.
1039 */
1040static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1041                    int (*compare)(const struct device *a,
1042                            const struct device *b))
1043{
1044    struct list_head *pos;
1045    struct klist_node *n;
1046    struct device_private *dev_prv;
1047    struct device *b;
1048
1049    list_for_each(pos, list) {
1050        n = container_of(pos, struct klist_node, n_node);
1051        dev_prv = to_device_private_bus(n);
1052        b = dev_prv->device;
1053        if (compare(a, b) <= 0) {
1054            list_move_tail(&a->p->knode_bus.n_node,
1055                       &b->p->knode_bus.n_node);
1056            return;
1057        }
1058    }
1059    list_move_tail(&a->p->knode_bus.n_node, list);
1060}
1061
1062void bus_sort_breadthfirst(struct bus_type *bus,
1063               int (*compare)(const struct device *a,
1064                      const struct device *b))
1065{
1066    LIST_HEAD(sorted_devices);
1067    struct list_head *pos, *tmp;
1068    struct klist_node *n;
1069    struct device_private *dev_prv;
1070    struct device *dev;
1071    struct klist *device_klist;
1072
1073    device_klist = bus_get_device_klist(bus);
1074
1075    spin_lock(&device_klist->k_lock);
1076    list_for_each_safe(pos, tmp, &device_klist->k_list) {
1077        n = container_of(pos, struct klist_node, n_node);
1078        dev_prv = to_device_private_bus(n);
1079        dev = dev_prv->device;
1080        device_insertion_sort_klist(dev, &sorted_devices, compare);
1081    }
1082    list_splice(&sorted_devices, &device_klist->k_list);
1083    spin_unlock(&device_klist->k_lock);
1084}
1085EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1086
1087/**
1088 * subsys_dev_iter_init - initialize subsys device iterator
1089 * @iter: subsys iterator to initialize
1090 * @subsys: the subsys we wanna iterate over
1091 * @start: the device to start iterating from, if any
1092 * @type: device_type of the devices to iterate over, NULL for all
1093 *
1094 * Initialize subsys iterator @iter such that it iterates over devices
1095 * of @subsys. If @start is set, the list iteration will start there,
1096 * otherwise if it is NULL, the iteration starts at the beginning of
1097 * the list.
1098 */
1099void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
1100              struct device *start, const struct device_type *type)
1101{
1102    struct klist_node *start_knode = NULL;
1103
1104    if (start)
1105        start_knode = &start->p->knode_bus;
1106    klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
1107    iter->type = type;
1108}
1109EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
1110
1111/**
1112 * subsys_dev_iter_next - iterate to the next device
1113 * @iter: subsys iterator to proceed
1114 *
1115 * Proceed @iter to the next device and return it. Returns NULL if
1116 * iteration is complete.
1117 *
1118 * The returned device is referenced and won't be released till
1119 * iterator is proceed to the next device or exited. The caller is
1120 * free to do whatever it wants to do with the device including
1121 * calling back into subsys code.
1122 */
1123struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
1124{
1125    struct klist_node *knode;
1126    struct device *dev;
1127
1128    for (;;) {
1129        knode = klist_next(&iter->ki);
1130        if (!knode)
1131            return NULL;
1132        dev = container_of(knode, struct device_private, knode_bus)->device;
1133        if (!iter->type || iter->type == dev->type)
1134            return dev;
1135    }
1136}
1137EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1138
1139/**
1140 * subsys_dev_iter_exit - finish iteration
1141 * @iter: subsys iterator to finish
1142 *
1143 * Finish an iteration. Always call this function after iteration is
1144 * complete whether the iteration ran till the end or not.
1145 */
1146void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1147{
1148    klist_iter_exit(&iter->ki);
1149}
1150EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1151
1152int subsys_interface_register(struct subsys_interface *sif)
1153{
1154    struct bus_type *subsys;
1155    struct subsys_dev_iter iter;
1156    struct device *dev;
1157
1158    if (!sif || !sif->subsys)
1159        return -ENODEV;
1160
1161    subsys = bus_get(sif->subsys);
1162    if (!subsys)
1163        return -EINVAL;
1164
1165    mutex_lock(&subsys->p->mutex);
1166    list_add_tail(&sif->node, &subsys->p->interfaces);
1167    if (sif->add_dev) {
1168        subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1169        while ((dev = subsys_dev_iter_next(&iter)))
1170            sif->add_dev(dev, sif);
1171        subsys_dev_iter_exit(&iter);
1172    }
1173    mutex_unlock(&subsys->p->mutex);
1174
1175    return 0;
1176}
1177EXPORT_SYMBOL_GPL(subsys_interface_register);
1178
1179void subsys_interface_unregister(struct subsys_interface *sif)
1180{
1181    struct bus_type *subsys;
1182    struct subsys_dev_iter iter;
1183    struct device *dev;
1184
1185    if (!sif || !sif->subsys)
1186        return;
1187
1188    subsys = sif->subsys;
1189
1190    mutex_lock(&subsys->p->mutex);
1191    list_del_init(&sif->node);
1192    if (sif->remove_dev) {
1193        subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1194        while ((dev = subsys_dev_iter_next(&iter)))
1195            sif->remove_dev(dev, sif);
1196        subsys_dev_iter_exit(&iter);
1197    }
1198    mutex_unlock(&subsys->p->mutex);
1199
1200    bus_put(subsys);
1201}
1202EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1203
1204static void system_root_device_release(struct device *dev)
1205{
1206    kfree(dev);
1207}
1208/**
1209 * subsys_system_register - register a subsystem at /sys/devices/system/
1210 * @subsys: system subsystem
1211 * @groups: default attributes for the root device
1212 *
1213 * All 'system' subsystems have a /sys/devices/system/<name> root device
1214 * with the name of the subsystem. The root device can carry subsystem-
1215 * wide attributes. All registered devices are below this single root
1216 * device and are named after the subsystem with a simple enumeration
1217 * number appended. The registered devices are not explicitely named;
1218 * only 'id' in the device needs to be set.
1219 *
1220 * Do not use this interface for anything new, it exists for compatibility
1221 * with bad ideas only. New subsystems should use plain subsystems; and
1222 * add the subsystem-wide attributes should be added to the subsystem
1223 * directory itself and not some create fake root-device placed in
1224 * /sys/devices/system/<name>.
1225 */
1226int subsys_system_register(struct bus_type *subsys,
1227               const struct attribute_group **groups)
1228{
1229    struct device *dev;
1230    int err;
1231
1232    err = bus_register(subsys);
1233    if (err < 0)
1234        return err;
1235
1236    dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1237    if (!dev) {
1238        err = -ENOMEM;
1239        goto err_dev;
1240    }
1241
1242    err = dev_set_name(dev, "%s", subsys->name);
1243    if (err < 0)
1244        goto err_name;
1245
1246    dev->kobj.parent = &system_kset->kobj;
1247    dev->groups = groups;
1248    dev->release = system_root_device_release;
1249
1250    err = device_register(dev);
1251    if (err < 0)
1252        goto err_dev_reg;
1253
1254    subsys->dev_root = dev;
1255    return 0;
1256
1257err_dev_reg:
1258    put_device(dev);
1259    dev = NULL;
1260err_name:
1261    kfree(dev);
1262err_dev:
1263    bus_unregister(subsys);
1264    return err;
1265}
1266EXPORT_SYMBOL_GPL(subsys_system_register);
1267
1268int __init buses_init(void)
1269{
1270    bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1271    if (!bus_kset)
1272        return -ENOMEM;
1273
1274    system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1275    if (!system_kset)
1276        return -ENOMEM;
1277
1278    return 0;
1279}
1280

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