/*
* attribute_container.c - implementation of a simple container for classes
*
* Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
*
* This file is licensed under GPLv2
*
* The basic idea here is to enable a device to be attached to an
* aritrary numer of classes without having to allocate storage for them.
* Instead, the contained classes select the devices they need to attach
* to via a matching function.
*/
#include <linux/attribute_container.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include "base.h"
/* This is a private structure used to tie the classdev and the
* container .. it should never be visible outside this file */
struct internal_container {
struct klist_node node;
struct attribute_container *cont;
struct class_device classdev;
};
static void internal_container_klist_get(struct klist_node *n)
{
struct internal_container *ic =
container_of(n, struct internal_container, node);
class_device_get(&ic->classdev);
}
static void internal_container_klist_put(struct klist_node *n)
{
struct internal_container *ic =
container_of(n, struct internal_container, node);
class_device_put(&ic->classdev);
}
/**
* attribute_container_classdev_to_container - given a classdev, return the container
*
* @classdev: the class device created by attribute_container_add_device.
*
* Returns the container associated with this classdev.
*/
struct attribute_container *
attribute_container_classdev_to_container(struct class_device *classdev)
{
struct internal_container *ic =
container_of(classdev, struct internal_container, classdev);
return ic->cont;
}
EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
static struct list_head attribute_container_list;
static DEFINE_MUTEX(attribute_container_mutex);
/**
* attribute_container_register - register an attribute container
*
* @cont: The container to register. This must be allocated by the
* callee and should also be zeroed by it.
*/
int
attribute_container_register(struct attribute_container *cont)
{
INIT_LIST_HEAD(&cont->node);
klist_init(&cont->containers,internal_container_klist_get,
internal_container_klist_put);
mutex_lock(&attribute_container_mutex);
list_add_tail(&cont->node, &attribute_container_list);
mutex_unlock(&attribute_container_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(attribute_container_register);
/**
* attribute_container_unregister - remove a container registration
*
* @cont: previously registered container to remove
*/
int
attribute_container_unregister(struct attribute_container *cont)
{
int retval = -EBUSY;
mutex_lock(&attribute_container_mutex);
spin_lock(&cont->containers.k_lock);
if (!list_empty(&cont->containers.k_list))
goto out;
retval = 0;
list_del(&cont->node);
out:
spin_unlock(&cont->containers.k_lock);
mutex_unlock(&attribute_container_mutex);
return retval;
}
EXPORT_SYMBOL_GPL(attribute_container_unregister);
/* private function used as class release */
static void attribute_container_release(struct class_device *classdev)
{
struct internal_container *ic
= container_of(classdev, struct internal_container, classdev);
struct device *dev = classdev->dev;
kfree(ic);
put_device(dev);
}
/**
* attribute_container_add_device - see if any container is interested in dev
*
* @dev: device to add attributes to
* @fn: function to trigger addition of class device.
*
* This function allocates storage for the class device(s) to be
* attached to dev (one for each matching attribute_container). If no
* fn is provided, the code will simply register the class device via
* class_device_add. If a function is provided, it is expected to add
* the class device at the appropriate time. One of the things that
* might be necessary is to allocate and initialise the classdev and
* then add it a later time. To do this, call this routine for
* allocation and initialisation and then use
* attribute_container_device_trigger() to call class_device_add() on
* it. Note: after this, the class device contains a reference to dev
* which is not relinquished until the release of the classdev.
*/
void
attribute_container_add_device(struct device *dev,
int (*fn)(struct attribute_container *,
struct device *,
struct class_device *))
{
struct attribute_container *cont;
mutex_lock(&attribute_container_mutex);
list_for_each_entry(cont, &attribute_container_list, node) {
struct internal_container *ic;
if (attribute_container_no_classdevs(cont))
continue;
if (!cont->match(cont, dev))
continue;
ic = kzalloc(sizeof(*ic), GFP_KERNEL);
if (!ic) {
dev_printk(KERN_ERR, dev, "failed to allocate class container\n");
continue;
}
ic->cont = cont;
class_device_initialize(&ic->classdev);
ic->classdev.dev = get_device(dev);
ic->classdev.class = cont->class;
cont->class->release = attribute_container_release;
strcpy(ic->classdev.class_id, dev->bus_id);
if (fn)
fn(cont, dev, &ic->classdev);
else
attribute_container_add_class_device(&ic->classdev);
klist_add_tail(&ic->node, &cont->containers);
}
mutex_unlock(&attribute_container_mutex);
}
/* FIXME: can't break out of this unless klist_iter_exit is also
* called before doing the break
*/
#define klist_for_each_entry(pos, head, member, iter) \
for (klist_iter_init(head, iter); (pos = ({ \
struct klist_node *n = klist_next(iter); \
n ? container_of(n, typeof(*pos), member) : \
({ klist_iter_exit(iter) ; NULL; }); \
}) ) != NULL; )
/**
* attribute_container_remove_device - make device eligible for removal.
*
* @dev: The generic device
* @fn: A function to call to remove the device
*
* This routine triggers device removal. If fn is NULL, then it is
* simply done via class_device_unregister (note that if something
* still has a reference to the classdev, then the memory occupied
* will not be freed until the classdev is released). If you want a
* two phase release: remove from visibility and then delete the
* device, then you should use this routine with a fn that calls
* class_device_del() and then use
* attribute_container_device_trigger() to do the final put on the
* classdev.
*/
void
attribute_container_remove_device(struct device *dev,
void (*fn)(struct attribute_container *,
struct device *,
struct class_device *))
{
struct attribute_container *cont;
mutex_lock(&attribute_container_mutex);
list_for_each_entry(cont, &attribute_container_list, node) {
struct internal_container *ic;
struct klist_iter iter;
if (attribute_container_no_classdevs(cont))
continue;
if (!cont->match(cont, dev))
continue;
klist_for_each_entry(ic, &cont->containers, node, &iter) {
if (dev != ic->classdev.dev)
continue;
klist_del(&ic->node);
if (fn)
fn(cont, dev, &ic->classdev);
else {
attribute_container_remove_attrs(&ic->classdev);
class_device_unregister(&ic->classdev);
}
}
}
mutex_unlock(&attribute_container_mutex);
}
/**
* attribute_container_device_trigger - execute a trigger for each matching classdev
*
* @dev: The generic device to run the trigger for
* @fn the function to execute for each classdev.
*
* This funcion is for executing a trigger when you need to know both
* the container and the classdev. If you only care about the
* container, then use attribute_container_trigger() instead.
*/
void
attribute_container_device_trigger(struct device *dev,
int (*fn)(struct attribute_container *,
struct device *,
struct class_device *))
{
struct attribute_container *cont;
mutex_lock(&attribute_container_mutex);
list_for_each_entry(cont, &attribute_container_list, node) {
struct internal_container *ic;
struct klist_iter iter;
if (!cont->match(cont, dev))
continue;
if (attribute_container_no_classdevs(cont)) {
fn(cont, dev, NULL);
continue;
}
klist_for_each_entry(ic, &cont->containers, node, &iter) {
if (dev == ic->classdev.dev)
fn(cont, dev, &ic->classdev);
}
}
mutex_unlock(&attribute_container_mutex);
}
/**
* attribute_container_trigger - trigger a function for each matching container
*
* @dev: The generic device to activate the trigger for
* @fn: the function to trigger
*
* This routine triggers a function that only needs to know the
* matching containers (not the classdev) associated with a device.
* It is more lightweight than attribute_container_device_trigger, so
* should be used in preference unless the triggering function
* actually needs to know the classdev.
*/
void
attribute_container_trigger(struct device *dev,
int (*fn)(struct attribute_container *,
struct device *))
{
struct attribute_container *cont;
mutex_lock(&attribute_container_mutex);
list_for_each_entry(cont, &attribute_container_list, node) {
if (cont->match(cont, dev))
fn(cont, dev);
}
mutex_unlock(&attribute_container_mutex);
}
/**
* attribute_container_add_attrs - add attributes
*
* @classdev: The class device
*
* This simply creates all the class device sysfs files from the
* attributes listed in the container
*/
int
attribute_container_add_attrs(struct class_device *classdev)
{
struct attribute_container *cont =
attribute_container_classdev_to_container(classdev);
struct class_device_attribute **attrs = cont->attrs;
int i, error;
if (!attrs)
return 0;
for (i = 0; attrs[i]; i++) {
error = class_device_create_file(classdev, attrs[i]);
if (error)
return error;
}
return 0;
}
/**
* attribute_container_add_class_device - same function as class_device_add
*
* @classdev: the class device to add
*
* This performs essentially the same function as class_device_add except for
* attribute containers, namely add the classdev to the system and then
* create the attribute files
*/
int
attribute_container_add_class_device(struct class_device *classdev)
{
int error = class_device_add(classdev);
if (error)
return error;
return attribute_container_add_attrs(classdev);
}
/**
* attribute_container_add_class_device_adapter - simple adapter for triggers
*
* This function is identical to attribute_container_add_class_device except
* that it is designed to be called from the triggers
*/
int
attribute_container_add_class_device_adapter(struct attribute_container *cont,
struct device *dev,
struct class_device *classdev)
{
return attribute_container_add_class_device(classdev);
}
/**
* attribute_container_remove_attrs - remove any attribute files
*
* @classdev: The class device to remove the files from
*
*/
void
attribute_container_remove_attrs(struct class_device *classdev)
{
struct attribute_container *cont =
attribute_container_classdev_to_container(classdev);
struct class_device_attribute **attrs = cont->attrs;
int i;
if (!attrs)
return;
for (i = 0; attrs[i]; i++)
class_device_remove_file(classdev, attrs[i]);
}
/**
* attribute_container_class_device_del - equivalent of class_device_del
*
* @classdev: the class device
*
* This function simply removes all the attribute files and then calls
* class_device_del.
*/
void
attribute_container_class_device_del(struct class_device *classdev)
{
attribute_container_remove_attrs(classdev);
class_device_del(classdev);
}
/**
* attribute_container_find_class_device - find the corresponding class_device
*
* @cont: the container
* @dev: the generic device
*
* Looks up the device in the container's list of class devices and returns
* the corresponding class_device.
*/
struct class_device *
attribute_container_find_class_device(struct attribute_container *cont,
struct device *dev)
{
struct class_device *cdev = NULL;
struct internal_container *ic;
struct klist_iter iter;
klist_for_each_entry(ic, &cont->containers, node, &iter) {
if (ic->classdev.dev == dev) {
cdev = &ic->classdev;
/* FIXME: must exit iterator then break */
klist_iter_exit(&iter);
break;
}
}
return cdev;
}
EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
int __init
attribute_container_init(void)
{
INIT_LIST_HEAD(&attribute_container_list);
return 0;
}
