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 <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);
}

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);

void class_destroy(struct class *cls)
{
    if ((cls == NULL) || (IS_ERR(cls)))
        return;

    class_unregister(cls);
}

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);

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);

void class_dev_iter_exit(struct class_dev_iter *iter)
{
    klist_iter_exit(&iter->ki);
}
EXPORT_SYMBOL_GPL(class_dev_iter_exit);

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);

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;
};

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);

void class_compat_unregister(struct class_compat *cls)
{
    kobject_put(cls->kobj);
    kfree(cls);
}
EXPORT_SYMBOL_GPL(class_compat_unregister);

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);

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);