- 根目录:
- drivers
- base
- class.c
/*
* class.c - basic device class management
*
* Copyright (c) 2002-3 Patrick Mochel
* Copyright (c) 2002-3 Open Source Development Labs
* Copyright (c) 2003-2004 Greg Kroah-Hartman
* Copyright (c) 2003-2004 IBM Corp.
*
* This file is released under the GPLv2
*
*/
#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/kdev_t.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/genhd.h>
#include <linux/mutex.h>
#include "base.h"
#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
char *buf)
{
struct class_attribute *class_attr = to_class_attr(attr);
struct subsys_private *cp = to_subsys_private(kobj);
ssize_t ret = -EIO;
if (class_attr->show)
ret = class_attr->show(cp->class, class_attr, buf);
return ret;
}
static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
const char *buf, size_t count)
{
struct class_attribute *class_attr = to_class_attr(attr);
struct subsys_private *cp = to_subsys_private(kobj);
ssize_t ret = -EIO;
if (class_attr->store)
ret = class_attr->store(cp->class, class_attr, buf, count);
return ret;
}
static const void *class_attr_namespace(struct kobject *kobj,
const struct attribute *attr)
{
struct class_attribute *class_attr = to_class_attr(attr);
struct subsys_private *cp = to_subsys_private(kobj);
const void *ns = NULL;
if (class_attr->namespace)
ns = class_attr->namespace(cp->class, class_attr);
return ns;
}
static void class_release(struct kobject *kobj)
{
struct subsys_private *cp = to_subsys_private(kobj);
struct class *class = cp->class;
pr_debug("class '%s': release.\n", class->name);
if (class->class_release)
class->class_release(class);
else
pr_debug("class '%s' does not have a release() function, "
"be careful\n", class->name);
kfree(cp);
}
static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
{
struct subsys_private *cp = to_subsys_private(kobj);
struct class *class = cp->class;
return class->ns_type;
}
static const struct sysfs_ops class_sysfs_ops = {
.show = class_attr_show,
.store = class_attr_store,
.namespace = class_attr_namespace,
};
static struct kobj_type class_ktype = {
.sysfs_ops = &class_sysfs_ops,
.release = class_release,
.child_ns_type = class_child_ns_type,
};
/* Hotplug events for classes go to the class subsys */
static struct kset *class_kset;
int class_create_file(struct class *cls, const struct class_attribute *attr)
{
int error;
if (cls)
error = sysfs_create_file(&cls->p->subsys.kobj,
&attr->attr);
else
error = -EINVAL;
return error;
}
void class_remove_file(struct class *cls, const struct class_attribute *attr)
{
if (cls)
sysfs_remove_file(&cls->p->subsys.kobj, &attr->attr);
}
static struct class *class_get(struct class *cls)
{
if (cls)
kset_get(&cls->p->subsys);
return cls;
}
static void class_put(struct class *cls)
{
if (cls)
kset_put(&cls->p->subsys);
}
static int add_class_attrs(struct class *cls)
{
int i;
int error = 0;
if (cls->class_attrs) {
for (i = 0; attr_name(cls->class_attrs[i]); i++) {
error = class_create_file(cls, &cls->class_attrs[i]);
if (error)
goto error;
}
}
done:
return error;
error:
while (--i >= 0)
class_remove_file(cls, &cls->class_attrs[i]);
goto done;
}
static void remove_class_attrs(struct class *cls)
{
int i;
if (cls->class_attrs) {
for (i = 0; attr_name(cls->class_attrs[i]); i++)
class_remove_file(cls, &cls->class_attrs[i]);
}
}
static void klist_class_dev_get(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_class);
get_device(dev);
}
static void klist_class_dev_put(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_class);
put_device(dev);
}
int __class_register(struct class *cls, struct lock_class_key *key)
{
struct subsys_private *cp;
int error;
pr_debug("device class '%s': registering\n", cls->name);
cp = kzalloc(sizeof(*cp), GFP_KERNEL);
if (!cp)
return -ENOMEM;
klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
INIT_LIST_HEAD(&cp->interfaces);
kset_init(&cp->glue_dirs);
__mutex_init(&cp->mutex, "subsys mutex", key);
error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
if (error) {
kfree(cp);
return error;
}
/* set the default /sys/dev directory for devices of this class */
if (!cls->dev_kobj)
cls->dev_kobj = sysfs_dev_char_kobj;
#if defined(CONFIG_BLOCK)
/* let the block class directory show up in the root of sysfs */
if (!sysfs_deprecated || cls != &block_class)
cp->subsys.kobj.kset = class_kset;
#else
cp->subsys.kobj.kset = class_kset;
#endif
cp->subsys.kobj.ktype = &class_ktype;
cp->class = cls;
cls->p = cp;
error = kset_register(&cp->subsys);
if (error) {
kfree(cp);
return error;
}
error = add_class_attrs(class_get(cls));
class_put(cls);
return error;
}
EXPORT_SYMBOL_GPL(__class_register);
void class_unregister(struct class *cls)
{
pr_debug("device class '%s': unregistering\n", cls->name);
remove_class_attrs(cls);
kset_unregister(&cls->p->subsys);
}
static void class_create_release(struct class *cls)
{
pr_debug("%s called for %s\n", __func__, cls->name);
kfree(cls);
}
/**
* class_create - create a struct class structure
* @owner: pointer to the module that is to "own" this struct class
* @name: pointer to a string for the name of this class.
* @key: the lock_class_key for this class; used by mutex lock debugging
*
* This is used to create a struct class pointer that can then be used
* in calls to device_create().
*
* Returns &struct class pointer on success, or ERR_PTR() on error.
*
* Note, the pointer created here is to be destroyed when finished by
* making a call to class_destroy().
*/
struct class *__class_create(struct module *owner, const char *name,
struct lock_class_key *key)
{
struct class *cls;
int retval;
cls = kzalloc(sizeof(*cls), GFP_KERNEL);
if (!cls) {
retval = -ENOMEM;
goto error;
}
cls->name = name;
cls->owner = owner;
cls->class_release = class_create_release;
retval = __class_register(cls, key);
if (retval)
goto error;
return cls;
error:
kfree(cls);
return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(__class_create);
/**
* class_destroy - destroys a struct class structure
* @cls: pointer to the struct class that is to be destroyed
*
* Note, the pointer to be destroyed must have been created with a call
* to class_create().
*/
void class_destroy(struct class *cls)
{
if ((cls == NULL) || (IS_ERR(cls)))
return;
class_unregister(cls);
}
/**
* class_dev_iter_init - initialize class device iterator
* @iter: class iterator to initialize
* @class: the class we wanna iterate over
* @start: the device to start iterating from, if any
* @type: device_type of the devices to iterate over, NULL for all
*
* Initialize class iterator @iter such that it iterates over devices
* of @class. If @start is set, the list iteration will start there,
* otherwise if it is NULL, the iteration starts at the beginning of
* the list.
*/
void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
struct device *start, const struct device_type *type)
{
struct klist_node *start_knode = NULL;
if (start)
start_knode = &start->knode_class;
klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
iter->type = type;
}
EXPORT_SYMBOL_GPL(class_dev_iter_init);
/**
* class_dev_iter_next - iterate to the next device
* @iter: class iterator to proceed
*
* Proceed @iter to the next device and return it. Returns NULL if
* iteration is complete.
*
* The returned device is referenced and won't be released till
* iterator is proceed to the next device or exited. The caller is
* free to do whatever it wants to do with the device including
* calling back into class code.
*/
struct device *class_dev_iter_next(struct class_dev_iter *iter)
{
struct klist_node *knode;
struct device *dev;
while (1) {
knode = klist_next(&iter->ki);
if (!knode)
return NULL;
dev = container_of(knode, struct device, knode_class);
if (!iter->type || iter->type == dev->type)
return dev;
}
}
EXPORT_SYMBOL_GPL(class_dev_iter_next);
/**
* class_dev_iter_exit - finish iteration
* @iter: class iterator to finish
*
* Finish an iteration. Always call this function after iteration is
* complete whether the iteration ran till the end or not.
*/
void class_dev_iter_exit(struct class_dev_iter *iter)
{
klist_iter_exit(&iter->ki);
}
EXPORT_SYMBOL_GPL(class_dev_iter_exit);
/**
* class_for_each_device - device iterator
* @class: the class we're iterating
* @start: the device to start with in the list, if any.
* @data: data for the callback
* @fn: function to be called for each device
*
* Iterate over @class's list of devices, and call @fn for each,
* passing it @data. If @start is set, the list iteration will start
* there, otherwise if it is NULL, the iteration starts at the
* beginning of the list.
*
* We check the return of @fn each time. If it returns anything
* other than 0, we break out and return that value.
*
* @fn is allowed to do anything including calling back into class
* code. There's no locking restriction.
*/
int class_for_each_device(struct class *class, struct device *start,
void *data, int (*fn)(struct device *, void *))
{
struct class_dev_iter iter;
struct device *dev;
int error = 0;
if (!class)
return -EINVAL;
if (!class->p) {
WARN(1, "%s called for class '%s' before it was initialized",
__func__, class->name);
return -EINVAL;
}
class_dev_iter_init(&iter, class, start, NULL);
while ((dev = class_dev_iter_next(&iter))) {
error = fn(dev, data);
if (error)
break;
}
class_dev_iter_exit(&iter);
return error;
}
EXPORT_SYMBOL_GPL(class_for_each_device);
/**
* class_find_device - device iterator for locating a particular device
* @class: the class we're iterating
* @start: Device to begin with
* @data: data for the match function
* @match: function to check device
*
* This is similar to the class_for_each_dev() function above, but it
* returns a reference to a device that is 'found' for later use, as
* determined by the @match callback.
*
* The callback should return 0 if the device doesn't match and non-zero
* if it does. If the callback returns non-zero, this function will
* return to the caller and not iterate over any more devices.
*
* Note, you will need to drop the reference with put_device() after use.
*
* @fn is allowed to do anything including calling back into class
* code. There's no locking restriction.
*/
struct device *class_find_device(struct class *class, struct device *start,
void *data,
int (*match)(struct device *, void *))
{
struct class_dev_iter iter;
struct device *dev;
if (!class)
return NULL;
if (!class->p) {
WARN(1, "%s called for class '%s' before it was initialized",
__func__, class->name);
return NULL;
}
class_dev_iter_init(&iter, class, start, NULL);
while ((dev = class_dev_iter_next(&iter))) {
if (match(dev, data)) {
get_device(dev);
break;
}
}
class_dev_iter_exit(&iter);
return dev;
}
EXPORT_SYMBOL_GPL(class_find_device);
int class_interface_register(struct class_interface *class_intf)
{
struct class *parent;
struct class_dev_iter iter;
struct device *dev;
if (!class_intf || !class_intf->class)
return -ENODEV;
parent = class_get(class_intf->class);
if (!parent)
return -EINVAL;
mutex_lock(&parent->p->mutex);
list_add_tail(&class_intf->node, &parent->p->interfaces);
if (class_intf->add_dev) {
class_dev_iter_init(&iter, parent, NULL, NULL);
while ((dev = class_dev_iter_next(&iter)))
class_intf->add_dev(dev, class_intf);
class_dev_iter_exit(&iter);
}
mutex_unlock(&parent->p->mutex);
return 0;
}
void class_interface_unregister(struct class_interface *class_intf)
{
struct class *parent = class_intf->class;
struct class_dev_iter iter;
struct device *dev;
if (!parent)
return;
mutex_lock(&parent->p->mutex);
list_del_init(&class_intf->node);
if (class_intf->remove_dev) {
class_dev_iter_init(&iter, parent, NULL, NULL);
while ((dev = class_dev_iter_next(&iter)))
class_intf->remove_dev(dev, class_intf);
class_dev_iter_exit(&iter);
}
mutex_unlock(&parent->p->mutex);
class_put(parent);
}
ssize_t show_class_attr_string(struct class *class,
struct class_attribute *attr, char *buf)
{
struct class_attribute_string *cs;
cs = container_of(attr, struct class_attribute_string, attr);
return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
}
EXPORT_SYMBOL_GPL(show_class_attr_string);
struct class_compat {
struct kobject *kobj;
};
/**
* class_compat_register - register a compatibility class
* @name: the name of the class
*
* Compatibility class are meant as a temporary user-space compatibility
* workaround when converting a family of class devices to a bus devices.
*/
struct class_compat *class_compat_register(const char *name)
{
struct class_compat *cls;
cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
if (!cls)
return NULL;
cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
if (!cls->kobj) {
kfree(cls);
return NULL;
}
return cls;
}
EXPORT_SYMBOL_GPL(class_compat_register);
/**
* class_compat_unregister - unregister a compatibility class
* @cls: the class to unregister
*/
void class_compat_unregister(struct class_compat *cls)
{
kobject_put(cls->kobj);
kfree(cls);
}
EXPORT_SYMBOL_GPL(class_compat_unregister);
/**
* class_compat_create_link - create a compatibility class device link to
* a bus device
* @cls: the compatibility class
* @dev: the target bus device
* @device_link: an optional device to which a "device" link should be created
*/
int class_compat_create_link(struct class_compat *cls, struct device *dev,
struct device *device_link)
{
int error;
error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
if (error)
return error;
/*
* Optionally add a "device" link (typically to the parent), as a
* class device would have one and we want to provide as much
* backwards compatibility as possible.
*/
if (device_link) {
error = sysfs_create_link(&dev->kobj, &device_link->kobj,
"device");
if (error)
sysfs_remove_link(cls->kobj, dev_name(dev));
}
return error;
}
EXPORT_SYMBOL_GPL(class_compat_create_link);
/**
* class_compat_remove_link - remove a compatibility class device link to
* a bus device
* @cls: the compatibility class
* @dev: the target bus device
* @device_link: an optional device to which a "device" link was previously
* created
*/
void class_compat_remove_link(struct class_compat *cls, struct device *dev,
struct device *device_link)
{
if (device_link)
sysfs_remove_link(&dev->kobj, "device");
sysfs_remove_link(cls->kobj, dev_name(dev));
}
EXPORT_SYMBOL_GPL(class_compat_remove_link);
int __init classes_init(void)
{
class_kset = kset_create_and_add("class", NULL, NULL);
if (!class_kset)
return -ENOMEM;
return 0;
}
EXPORT_SYMBOL_GPL(class_create_file);
EXPORT_SYMBOL_GPL(class_remove_file);
EXPORT_SYMBOL_GPL(class_unregister);
EXPORT_SYMBOL_GPL(class_destroy);
EXPORT_SYMBOL_GPL(class_interface_register);
EXPORT_SYMBOL_GPL(class_interface_unregister);