2 * drivers/base/core.c - core driver model code (device registration, etc)
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
7 * This file is released under the GPLv2
11 #include <linux/config.h>
12 #include <linux/device.h>
13 #include <linux/err.h>
14 #include <linux/init.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/string.h>
18 #include <linux/kdev_t.h>
20 #include <asm/semaphore.h>
23 #include "power/power.h"
25 int (*platform_notify)(struct device * dev) = NULL;
26 int (*platform_notify_remove)(struct device * dev) = NULL;
29 * sysfs bindings for devices.
32 #define to_dev(obj) container_of(obj, struct device, kobj)
33 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
36 dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
38 struct device_attribute * dev_attr = to_dev_attr(attr);
39 struct device * dev = to_dev(kobj);
43 ret = dev_attr->show(dev, dev_attr, buf);
48 dev_attr_store(struct kobject * kobj, struct attribute * attr,
49 const char * buf, size_t count)
51 struct device_attribute * dev_attr = to_dev_attr(attr);
52 struct device * dev = to_dev(kobj);
56 ret = dev_attr->store(dev, dev_attr, buf, count);
60 static struct sysfs_ops dev_sysfs_ops = {
61 .show = dev_attr_show,
62 .store = dev_attr_store,
67 * device_release - free device structure.
68 * @kobj: device's kobject.
70 * This is called once the reference count for the object
71 * reaches 0. We forward the call to the device's release
72 * method, which should handle actually freeing the structure.
74 static void device_release(struct kobject * kobj)
76 struct device * dev = to_dev(kobj);
81 printk(KERN_ERR "Device '%s' does not have a release() function, "
82 "it is broken and must be fixed.\n",
88 static struct kobj_type ktype_device = {
89 .release = device_release,
90 .sysfs_ops = &dev_sysfs_ops,
94 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
96 struct kobj_type *ktype = get_ktype(kobj);
98 if (ktype == &ktype_device) {
99 struct device *dev = to_dev(kobj);
108 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
110 struct device *dev = to_dev(kobj);
113 return dev->bus->name;
115 return dev->class->name;
119 static int dev_uevent(struct kset *kset, struct kobject *kobj, char **envp,
120 int num_envp, char *buffer, int buffer_size)
122 struct device *dev = to_dev(kobj);
127 /* add the major/minor if present */
128 if (MAJOR(dev->devt)) {
129 add_uevent_var(envp, num_envp, &i,
130 buffer, buffer_size, &length,
131 "MAJOR=%u", MAJOR(dev->devt));
132 add_uevent_var(envp, num_envp, &i,
133 buffer, buffer_size, &length,
134 "MINOR=%u", MINOR(dev->devt));
137 /* add bus name of physical device */
139 add_uevent_var(envp, num_envp, &i,
140 buffer, buffer_size, &length,
141 "PHYSDEVBUS=%s", dev->bus->name);
143 /* add driver name of physical device */
145 add_uevent_var(envp, num_envp, &i,
146 buffer, buffer_size, &length,
147 "PHYSDEVDRIVER=%s", dev->driver->name);
149 /* terminate, set to next free slot, shrink available space */
153 buffer = &buffer[length];
154 buffer_size -= length;
156 if (dev->bus && dev->bus->uevent) {
157 /* have the bus specific function add its stuff */
158 retval = dev->bus->uevent(dev, envp, num_envp, buffer, buffer_size);
160 pr_debug ("%s - uevent() returned %d\n",
161 __FUNCTION__, retval);
168 static struct kset_uevent_ops device_uevent_ops = {
169 .filter = dev_uevent_filter,
170 .name = dev_uevent_name,
171 .uevent = dev_uevent,
174 static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
175 const char *buf, size_t count)
177 kobject_uevent(&dev->kobj, KOBJ_ADD);
181 static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
184 return print_dev_t(buf, dev->devt);
188 * devices_subsys - structure to be registered with kobject core.
191 decl_subsys(devices, &ktype_device, &device_uevent_ops);
195 * device_create_file - create sysfs attribute file for device.
197 * @attr: device attribute descriptor.
200 int device_create_file(struct device * dev, struct device_attribute * attr)
203 if (get_device(dev)) {
204 error = sysfs_create_file(&dev->kobj, &attr->attr);
211 * device_remove_file - remove sysfs attribute file.
213 * @attr: device attribute descriptor.
216 void device_remove_file(struct device * dev, struct device_attribute * attr)
218 if (get_device(dev)) {
219 sysfs_remove_file(&dev->kobj, &attr->attr);
224 static void klist_children_get(struct klist_node *n)
226 struct device *dev = container_of(n, struct device, knode_parent);
231 static void klist_children_put(struct klist_node *n)
233 struct device *dev = container_of(n, struct device, knode_parent);
240 * device_initialize - init device structure.
243 * This prepares the device for use by other layers,
244 * including adding it to the device hierarchy.
245 * It is the first half of device_register(), if called by
246 * that, though it can also be called separately, so one
247 * may use @dev's fields (e.g. the refcount).
250 void device_initialize(struct device *dev)
252 kobj_set_kset_s(dev, devices_subsys);
253 kobject_init(&dev->kobj);
254 klist_init(&dev->klist_children, klist_children_get,
256 INIT_LIST_HEAD(&dev->dma_pools);
257 INIT_LIST_HEAD(&dev->node);
258 init_MUTEX(&dev->sem);
259 device_init_wakeup(dev, 0);
263 * device_add - add device to device hierarchy.
266 * This is part 2 of device_register(), though may be called
267 * separately _iff_ device_initialize() has been called separately.
269 * This adds it to the kobject hierarchy via kobject_add(), adds it
270 * to the global and sibling lists for the device, then
271 * adds it to the other relevant subsystems of the driver model.
273 int device_add(struct device *dev)
275 struct device *parent = NULL;
278 dev = get_device(dev);
279 if (!dev || !strlen(dev->bus_id))
282 parent = get_device(dev->parent);
284 pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
286 /* first, register with generic layer. */
287 kobject_set_name(&dev->kobj, "%s", dev->bus_id);
289 dev->kobj.parent = &parent->kobj;
291 if ((error = kobject_add(&dev->kobj)))
294 dev->uevent_attr.attr.name = "uevent";
295 dev->uevent_attr.attr.mode = S_IWUSR;
297 dev->uevent_attr.attr.owner = dev->driver->owner;
298 dev->uevent_attr.store = store_uevent;
299 device_create_file(dev, &dev->uevent_attr);
301 if (MAJOR(dev->devt)) {
302 struct device_attribute *attr;
303 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
308 attr->attr.name = "dev";
309 attr->attr.mode = S_IRUGO;
311 attr->attr.owner = dev->driver->owner;
312 attr->show = show_dev;
313 error = device_create_file(dev, attr);
319 dev->devt_attr = attr;
323 sysfs_create_link(&dev->kobj, &dev->class->subsys.kset.kobj,
325 sysfs_create_link(&dev->class->subsys.kset.kobj, &dev->kobj,
329 if ((error = device_pm_add(dev)))
331 if ((error = bus_add_device(dev)))
333 kobject_uevent(&dev->kobj, KOBJ_ADD);
334 bus_attach_device(dev);
336 klist_add_tail(&dev->knode_parent, &parent->klist_children);
338 /* notify platform of device entry */
340 platform_notify(dev);
345 device_pm_remove(dev);
347 if (dev->devt_attr) {
348 device_remove_file(dev, dev->devt_attr);
349 kfree(dev->devt_attr);
352 kobject_uevent(&dev->kobj, KOBJ_REMOVE);
353 kobject_del(&dev->kobj);
362 * device_register - register a device with the system.
363 * @dev: pointer to the device structure
365 * This happens in two clean steps - initialize the device
366 * and add it to the system. The two steps can be called
367 * separately, but this is the easiest and most common.
368 * I.e. you should only call the two helpers separately if
369 * have a clearly defined need to use and refcount the device
370 * before it is added to the hierarchy.
373 int device_register(struct device *dev)
375 device_initialize(dev);
376 return device_add(dev);
381 * get_device - increment reference count for device.
384 * This simply forwards the call to kobject_get(), though
385 * we do take care to provide for the case that we get a NULL
389 struct device * get_device(struct device * dev)
391 return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
396 * put_device - decrement reference count.
397 * @dev: device in question.
399 void put_device(struct device * dev)
402 kobject_put(&dev->kobj);
407 * device_del - delete device from system.
410 * This is the first part of the device unregistration
411 * sequence. This removes the device from the lists we control
412 * from here, has it removed from the other driver model
413 * subsystems it was added to in device_add(), and removes it
414 * from the kobject hierarchy.
416 * NOTE: this should be called manually _iff_ device_add() was
417 * also called manually.
420 void device_del(struct device * dev)
422 struct device * parent = dev->parent;
425 klist_del(&dev->knode_parent);
427 device_remove_file(dev, dev->devt_attr);
429 sysfs_remove_link(&dev->kobj, "subsystem");
430 sysfs_remove_link(&dev->class->subsys.kset.kobj, dev->bus_id);
432 device_remove_file(dev, &dev->uevent_attr);
434 /* Notify the platform of the removal, in case they
435 * need to do anything...
437 if (platform_notify_remove)
438 platform_notify_remove(dev);
439 bus_remove_device(dev);
440 device_pm_remove(dev);
441 kobject_uevent(&dev->kobj, KOBJ_REMOVE);
442 kobject_del(&dev->kobj);
448 * device_unregister - unregister device from system.
449 * @dev: device going away.
451 * We do this in two parts, like we do device_register(). First,
452 * we remove it from all the subsystems with device_del(), then
453 * we decrement the reference count via put_device(). If that
454 * is the final reference count, the device will be cleaned up
455 * via device_release() above. Otherwise, the structure will
456 * stick around until the final reference to the device is dropped.
458 void device_unregister(struct device * dev)
460 pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
466 static struct device * next_device(struct klist_iter * i)
468 struct klist_node * n = klist_next(i);
469 return n ? container_of(n, struct device, knode_parent) : NULL;
473 * device_for_each_child - device child iterator.
474 * @parent: parent struct device.
475 * @data: data for the callback.
476 * @fn: function to be called for each device.
478 * Iterate over @parent's child devices, and call @fn for each,
481 * We check the return of @fn each time. If it returns anything
482 * other than 0, we break out and return that value.
484 int device_for_each_child(struct device * parent, void * data,
485 int (*fn)(struct device *, void *))
488 struct device * child;
491 klist_iter_init(&parent->klist_children, &i);
492 while ((child = next_device(&i)) && !error)
493 error = fn(child, data);
498 int __init devices_init(void)
500 return subsystem_register(&devices_subsys);
503 EXPORT_SYMBOL_GPL(device_for_each_child);
505 EXPORT_SYMBOL_GPL(device_initialize);
506 EXPORT_SYMBOL_GPL(device_add);
507 EXPORT_SYMBOL_GPL(device_register);
509 EXPORT_SYMBOL_GPL(device_del);
510 EXPORT_SYMBOL_GPL(device_unregister);
511 EXPORT_SYMBOL_GPL(get_device);
512 EXPORT_SYMBOL_GPL(put_device);
514 EXPORT_SYMBOL_GPL(device_create_file);
515 EXPORT_SYMBOL_GPL(device_remove_file);
518 static void device_create_release(struct device *dev)
520 pr_debug("%s called for %s\n", __FUNCTION__, dev->bus_id);
525 * device_create - creates a device and registers it with sysfs
526 * @cs: pointer to the struct class that this device should be registered to.
527 * @parent: pointer to the parent struct device of this new device, if any.
528 * @dev: the dev_t for the char device to be added.
529 * @fmt: string for the class device's name
531 * This function can be used by char device classes. A struct
532 * device will be created in sysfs, registered to the specified
534 * A "dev" file will be created, showing the dev_t for the device, if
535 * the dev_t is not 0,0.
536 * If a pointer to a parent struct device is passed in, the newly
537 * created struct device will be a child of that device in sysfs. The
538 * pointer to the struct device will be returned from the call. Any
539 * further sysfs files that might be required can be created using this
542 * Note: the struct class passed to this function must have previously
543 * been created with a call to class_create().
545 struct device *device_create(struct class *class, struct device *parent,
546 dev_t devt, char *fmt, ...)
549 struct device *dev = NULL;
550 int retval = -ENODEV;
552 if (class == NULL || IS_ERR(class))
554 if (parent == NULL) {
555 printk(KERN_WARNING "%s does not work yet for NULL parents\n", __FUNCTION__);
559 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
567 dev->parent = parent;
568 dev->release = device_create_release;
571 vsnprintf(dev->bus_id, BUS_ID_SIZE, fmt, args);
573 retval = device_register(dev);
577 /* tie the class to the device */
579 list_add_tail(&dev->node, &class->devices);
586 return ERR_PTR(retval);
588 EXPORT_SYMBOL_GPL(device_create);
591 * device_destroy - removes a device that was created with device_create()
592 * @class: the pointer to the struct class that this device was registered * with.
593 * @dev: the dev_t of the device that was previously registered.
595 * This call unregisters and cleans up a class device that was created with a
596 * call to class_device_create()
598 void device_destroy(struct class *class, dev_t devt)
600 struct device *dev = NULL;
601 struct device *dev_tmp;
604 list_for_each_entry(dev_tmp, &class->devices, node) {
605 if (dev_tmp->devt == devt) {
613 list_del_init(&dev->node);
614 device_unregister(dev);
617 EXPORT_SYMBOL_GPL(device_destroy);