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>
19 #include <asm/semaphore.h>
22 #include "power/power.h"
24 int (*platform_notify)(struct device * dev) = NULL;
25 int (*platform_notify_remove)(struct device * dev) = NULL;
28 * sysfs bindings for devices.
31 #define to_dev(obj) container_of(obj, struct device, kobj)
32 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
35 dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
37 struct device_attribute * dev_attr = to_dev_attr(attr);
38 struct device * dev = to_dev(kobj);
42 ret = dev_attr->show(dev, buf);
47 dev_attr_store(struct kobject * kobj, struct attribute * attr,
48 const char * buf, size_t count)
50 struct device_attribute * dev_attr = to_dev_attr(attr);
51 struct device * dev = to_dev(kobj);
55 ret = dev_attr->store(dev, buf, count);
59 static struct sysfs_ops dev_sysfs_ops = {
60 .show = dev_attr_show,
61 .store = dev_attr_store,
66 * device_release - free device structure.
67 * @kobj: device's kobject.
69 * This is called once the reference count for the object
70 * reaches 0. We forward the call to the device's release
71 * method, which should handle actually freeing the structure.
73 static void device_release(struct kobject * kobj)
75 struct device * dev = to_dev(kobj);
80 printk(KERN_ERR "Device '%s' does not have a release() function, "
81 "it is broken and must be fixed.\n",
87 static struct kobj_type ktype_device = {
88 .release = device_release,
89 .sysfs_ops = &dev_sysfs_ops,
93 static int dev_hotplug_filter(struct kset *kset, struct kobject *kobj)
95 struct kobj_type *ktype = get_ktype(kobj);
97 if (ktype == &ktype_device) {
98 struct device *dev = to_dev(kobj);
105 static const char *dev_hotplug_name(struct kset *kset, struct kobject *kobj)
107 struct device *dev = to_dev(kobj);
109 return dev->bus->name;
112 static int dev_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
113 int num_envp, char *buffer, int buffer_size)
115 struct device *dev = to_dev(kobj);
120 /* add bus name of physical device */
122 add_hotplug_env_var(envp, num_envp, &i,
123 buffer, buffer_size, &length,
124 "PHYSDEVBUS=%s", dev->bus->name);
126 /* add driver name of physical device */
128 add_hotplug_env_var(envp, num_envp, &i,
129 buffer, buffer_size, &length,
130 "PHYSDEVDRIVER=%s", dev->driver->name);
132 /* terminate, set to next free slot, shrink available space */
136 buffer = &buffer[length];
137 buffer_size -= length;
139 if (dev->bus && dev->bus->hotplug) {
140 /* have the bus specific function add its stuff */
141 retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size);
143 pr_debug ("%s - hotplug() returned %d\n",
144 __FUNCTION__, retval);
151 static struct kset_hotplug_ops device_hotplug_ops = {
152 .filter = dev_hotplug_filter,
153 .name = dev_hotplug_name,
154 .hotplug = dev_hotplug,
158 * device_subsys - structure to be registered with kobject core.
161 decl_subsys(devices, &ktype_device, &device_hotplug_ops);
165 * device_create_file - create sysfs attribute file for device.
167 * @attr: device attribute descriptor.
170 int device_create_file(struct device * dev, struct device_attribute * attr)
173 if (get_device(dev)) {
174 error = sysfs_create_file(&dev->kobj, &attr->attr);
181 * device_remove_file - remove sysfs attribute file.
183 * @attr: device attribute descriptor.
186 void device_remove_file(struct device * dev, struct device_attribute * attr)
188 if (get_device(dev)) {
189 sysfs_remove_file(&dev->kobj, &attr->attr);
196 * device_initialize - init device structure.
199 * This prepares the device for use by other layers,
200 * including adding it to the device hierarchy.
201 * It is the first half of device_register(), if called by
202 * that, though it can also be called separately, so one
203 * may use @dev's fields (e.g. the refcount).
206 void device_initialize(struct device *dev)
208 kobj_set_kset_s(dev, devices_subsys);
209 kobject_init(&dev->kobj);
210 INIT_LIST_HEAD(&dev->node);
211 INIT_LIST_HEAD(&dev->children);
212 INIT_LIST_HEAD(&dev->driver_list);
213 INIT_LIST_HEAD(&dev->bus_list);
214 INIT_LIST_HEAD(&dev->dma_pools);
215 init_MUTEX(&dev->sem);
219 * device_add - add device to device hierarchy.
222 * This is part 2 of device_register(), though may be called
223 * separately _iff_ device_initialize() has been called separately.
225 * This adds it to the kobject hierarchy via kobject_add(), adds it
226 * to the global and sibling lists for the device, then
227 * adds it to the other relevant subsystems of the driver model.
229 int device_add(struct device *dev)
231 struct device *parent = NULL;
234 dev = get_device(dev);
235 if (!dev || !strlen(dev->bus_id))
238 parent = get_device(dev->parent);
240 pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
242 /* first, register with generic layer. */
243 kobject_set_name(&dev->kobj, "%s", dev->bus_id);
245 dev->kobj.parent = &parent->kobj;
247 if ((error = kobject_add(&dev->kobj)))
249 kobject_hotplug(&dev->kobj, KOBJ_ADD);
250 if ((error = device_pm_add(dev)))
252 if ((error = bus_add_device(dev)))
254 down_write(&devices_subsys.rwsem);
256 list_add_tail(&dev->node, &parent->children);
257 up_write(&devices_subsys.rwsem);
259 /* notify platform of device entry */
261 platform_notify(dev);
266 device_pm_remove(dev);
268 kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
269 kobject_del(&dev->kobj);
278 * device_register - register a device with the system.
279 * @dev: pointer to the device structure
281 * This happens in two clean steps - initialize the device
282 * and add it to the system. The two steps can be called
283 * separately, but this is the easiest and most common.
284 * I.e. you should only call the two helpers separately if
285 * have a clearly defined need to use and refcount the device
286 * before it is added to the hierarchy.
289 int device_register(struct device *dev)
291 device_initialize(dev);
292 return device_add(dev);
297 * get_device - increment reference count for device.
300 * This simply forwards the call to kobject_get(), though
301 * we do take care to provide for the case that we get a NULL
305 struct device * get_device(struct device * dev)
307 return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
312 * put_device - decrement reference count.
313 * @dev: device in question.
315 void put_device(struct device * dev)
318 kobject_put(&dev->kobj);
323 * device_del - delete device from system.
326 * This is the first part of the device unregistration
327 * sequence. This removes the device from the lists we control
328 * from here, has it removed from the other driver model
329 * subsystems it was added to in device_add(), and removes it
330 * from the kobject hierarchy.
332 * NOTE: this should be called manually _iff_ device_add() was
333 * also called manually.
336 void device_del(struct device * dev)
338 struct device * parent = dev->parent;
340 down_write(&devices_subsys.rwsem);
342 list_del_init(&dev->node);
343 up_write(&devices_subsys.rwsem);
345 /* Notify the platform of the removal, in case they
346 * need to do anything...
348 if (platform_notify_remove)
349 platform_notify_remove(dev);
350 bus_remove_device(dev);
351 device_pm_remove(dev);
352 kobject_hotplug(&dev->kobj, KOBJ_REMOVE);
353 kobject_del(&dev->kobj);
359 * device_unregister - unregister device from system.
360 * @dev: device going away.
362 * We do this in two parts, like we do device_register(). First,
363 * we remove it from all the subsystems with device_del(), then
364 * we decrement the reference count via put_device(). If that
365 * is the final reference count, the device will be cleaned up
366 * via device_release() above. Otherwise, the structure will
367 * stick around until the final reference to the device is dropped.
369 void device_unregister(struct device * dev)
371 pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
378 * device_for_each_child - device child iterator.
379 * @dev: parent struct device.
380 * @data: data for the callback.
381 * @fn: function to be called for each device.
383 * Iterate over @dev's child devices, and call @fn for each,
386 * We check the return of @fn each time. If it returns anything
387 * other than 0, we break out and return that value.
389 int device_for_each_child(struct device * dev, void * data,
390 int (*fn)(struct device *, void *))
392 struct device * child;
395 down_read(&devices_subsys.rwsem);
396 list_for_each_entry(child, &dev->children, node) {
397 if((error = fn(child, data)))
400 up_read(&devices_subsys.rwsem);
405 * device_find - locate device on a bus by name.
406 * @name: name of the device.
407 * @bus: bus to scan for the device.
409 * Call kset_find_obj() to iterate over list of devices on
410 * a bus to find device by name. Return device if found.
412 * Note that kset_find_obj increments device's reference count.
414 struct device *device_find(const char *name, struct bus_type *bus)
416 struct kobject *k = kset_find_obj(&bus->devices, name);
422 int __init devices_init(void)
424 return subsystem_register(&devices_subsys);
427 EXPORT_SYMBOL_GPL(device_for_each_child);
429 EXPORT_SYMBOL_GPL(device_initialize);
430 EXPORT_SYMBOL_GPL(device_add);
431 EXPORT_SYMBOL_GPL(device_register);
433 EXPORT_SYMBOL_GPL(device_del);
434 EXPORT_SYMBOL_GPL(device_unregister);
435 EXPORT_SYMBOL_GPL(get_device);
436 EXPORT_SYMBOL_GPL(put_device);
437 EXPORT_SYMBOL_GPL(device_find);
439 EXPORT_SYMBOL_GPL(device_create_file);
440 EXPORT_SYMBOL_GPL(device_remove_file);