linux/drivers/base/class.c

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/*
* 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 "base.h"
#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
#define to_class(obj) container_of(obj, struct class, subsys.kobj)
static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
char *buf)
{
struct class_attribute *class_attr = to_class_attr(attr);
struct class *dc = to_class(kobj);
ssize_t ret = -EIO;
if (class_attr->show)
ret = class_attr->show(dc, 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 class *dc = to_class(kobj);
ssize_t ret = -EIO;
if (class_attr->store)
ret = class_attr->store(dc, buf, count);
return ret;
}
static void class_release(struct kobject *kobj)
{
struct class *class = to_class(kobj);
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);
}
static struct sysfs_ops class_sysfs_ops = {
.show = class_attr_show,
.store = class_attr_store,
};
static struct kobj_type class_ktype = {
.sysfs_ops = &class_sysfs_ops,
.release = class_release,
};
/* Hotplug events for classes go to the class_obj 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->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->subsys.kobj, &attr->attr);
}
static struct class *class_get(struct class *cls)
{
if (cls)
return container_of(kset_get(&cls->subsys),
struct class, subsys);
return NULL;
}
static void class_put(struct class *cls)
{
if (cls)
kset_put(&cls->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]);
}
}
int class_register(struct class *cls)
{
int error;
pr_debug("device class '%s': registering\n", cls->name);
INIT_LIST_HEAD(&cls->devices);
INIT_LIST_HEAD(&cls->interfaces);
kset_init(&cls->class_dirs);
init_MUTEX(&cls->sem);
error = kobject_set_name(&cls->subsys.kobj, "%s", cls->name);
if (error)
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_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
/* let the block class directory show up in the root of sysfs */
if (cls != &block_class)
cls->subsys.kobj.kset = class_kset;
#else
cls->subsys.kobj.kset = class_kset;
#endif
cls->subsys.kobj.ktype = &class_ktype;
error = kset_register(&cls->subsys);
if (!error) {
error = add_class_attrs(class_get(cls));
class_put(cls);
}
return error;
}
void class_unregister(struct class *cls)
{
pr_debug("device class '%s': unregistering\n", cls->name);
remove_class_attrs(cls);
kset_unregister(&cls->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.
*
* This is used to create a struct class pointer that can then be used
* in calls to device_create().
*
* 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 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);
if (retval)
goto error;
return cls;
error:
kfree(cls);
return ERR_PTR(retval);
}
/**
* 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);
}
#ifdef CONFIG_SYSFS_DEPRECATED
char *make_class_name(const char *name, struct kobject *kobj)
{
char *class_name;
int size;
size = strlen(name) + strlen(kobject_name(kobj)) + 2;
class_name = kmalloc(size, GFP_KERNEL);
if (!class_name)
return NULL;
strcpy(class_name, name);
strcat(class_name, ":");
strcat(class_name, kobject_name(kobj));
return class_name;
}
#endif
/**
* 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.
*
* Note, we hold class->sem in this function, so it can not be
* re-acquired in @fn, otherwise it will self-deadlocking. For
* example, calls to add or remove class members would be verboten.
*/
int class_for_each_device(struct class *class, struct device *start,
void *data, int (*fn)(struct device *, void *))
{
struct device *dev;
int error = 0;
if (!class)
return -EINVAL;
down(&class->sem);
list_for_each_entry(dev, &class->devices, node) {
if (start) {
if (start == dev)
start = NULL;
continue;
}
dev = get_device(dev);
error = fn(dev, data);
put_device(dev);
if (error)
break;
}
up(&class->sem);
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.
*
* We hold class->sem in this function, so it can not be
* re-acquired in @match, otherwise it will self-deadlocking. For
* example, calls to add or remove class members would be verboten.
*/
struct device *class_find_device(struct class *class, struct device *start,
void *data,
int (*match)(struct device *, void *))
{
struct device *dev;
int found = 0;
if (!class)
return NULL;
down(&class->sem);
list_for_each_entry(dev, &class->devices, node) {
if (start) {
if (start == dev)
start = NULL;
continue;
}
dev = get_device(dev);
if (match(dev, data)) {
found = 1;
break;
} else
put_device(dev);
}
up(&class->sem);
return found ? dev : NULL;
}
EXPORT_SYMBOL_GPL(class_find_device);
int class_interface_register(struct class_interface *class_intf)
{
struct class *parent;
struct device *dev;
if (!class_intf || !class_intf->class)
return -ENODEV;
parent = class_get(class_intf->class);
if (!parent)
return -EINVAL;
down(&parent->sem);
list_add_tail(&class_intf->node, &parent->interfaces);
if (class_intf->add_dev) {
list_for_each_entry(dev, &parent->devices, node)
class_intf->add_dev(dev, class_intf);
}
up(&parent->sem);
return 0;
}
void class_interface_unregister(struct class_interface *class_intf)
{
struct class *parent = class_intf->class;
struct device *dev;
if (!parent)
return;
down(&parent->sem);
list_del_init(&class_intf->node);
if (class_intf->remove_dev) {
list_for_each_entry(dev, &parent->devices, node)
class_intf->remove_dev(dev, class_intf);
}
up(&parent->sem);
class_put(parent);
}
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_register);
EXPORT_SYMBOL_GPL(class_unregister);
EXPORT_SYMBOL_GPL(class_create);
EXPORT_SYMBOL_GPL(class_destroy);
EXPORT_SYMBOL_GPL(class_interface_register);
EXPORT_SYMBOL_GPL(class_interface_unregister);