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/*

 * 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;

}