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 "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 decl_subsys(class, &class_ktype, NULL);


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 Err;
		}
	}
 Done:
	return error;
 Err:
	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->children);
	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;

	cls->subsys.kobj.kset = &class_subsys;

	error = subsystem_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);
	subsystem_unregister(&cls->subsys);
}

static void class_create_release(struct class *cls)
{
	pr_debug("%s called for %s\n", __FUNCTION__, cls->name);
	kfree(cls);
}

static void class_device_create_release(struct class_device *class_dev)
{
	pr_debug("%s called for %s\n", __FUNCTION__, class_dev->class_id);
	kfree(class_dev);
}

/* needed to allow these devices to have parent class devices */
static int class_device_create_uevent(struct class_device *class_dev,
				      struct kobj_uevent_env *env)
{
	pr_debug("%s called for %s\n", __FUNCTION__, class_dev->class_id);
	return 0;
}

/**
 * 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 class_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;
	cls->release = class_device_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);
}

/* Class Device Stuff */

int class_device_create_file(struct class_device * class_dev,
			     const struct class_device_attribute * attr)
{
	int error = -EINVAL;
	if (class_dev)
		error = sysfs_create_file(&class_dev->kobj, &attr->attr);
	return error;
}

void class_device_remove_file(struct class_device * class_dev,
			      const struct class_device_attribute * attr)
{
	if (class_dev)
		sysfs_remove_file(&class_dev->kobj, &attr->attr);
}

int class_device_create_bin_file(struct class_device *class_dev,
				 struct bin_attribute *attr)
{
	int error = -EINVAL;
	if (class_dev)
		error = sysfs_create_bin_file(&class_dev->kobj, attr);
	return error;
}

void class_device_remove_bin_file(struct class_device *class_dev,
				  struct bin_attribute *attr)
{
	if (class_dev)
		sysfs_remove_bin_file(&class_dev->kobj, attr);
}

static ssize_t
class_device_attr_show(struct kobject * kobj, struct attribute * attr,
		       char * buf)
{
	struct class_device_attribute * class_dev_attr = to_class_dev_attr(attr);
	struct class_device * cd = to_class_dev(kobj);
	ssize_t ret = 0;

	if (class_dev_attr->show)
		ret = class_dev_attr->show(cd, buf);
	return ret;
}

static ssize_t
class_device_attr_store(struct kobject * kobj, struct attribute * attr,
			const char * buf, size_t count)
{
	struct class_device_attribute * class_dev_attr = to_class_dev_attr(attr);
	struct class_device * cd = to_class_dev(kobj);
	ssize_t ret = 0;

	if (class_dev_attr->store)
		ret = class_dev_attr->store(cd, buf, count);
	return ret;
}

static struct sysfs_ops class_dev_sysfs_ops = {
	.show	= class_device_attr_show,
	.store	= class_device_attr_store,
};

static void class_dev_release(struct kobject * kobj)
{
	struct class_device *cd = to_class_dev(kobj);
	struct class * cls = cd->class;

	pr_debug("device class '%s': release.\n", cd->class_id);

	if (cd->release)
		cd->release(cd);
	else if (cls->release)
		cls->release(cd);
	else {
		printk(KERN_ERR "Class Device '%s' does not have a release() function, "
			"it is broken and must be fixed.\n",
			cd->class_id);
		WARN_ON(1);
	}
}

static struct kobj_type class_device_ktype = {
	.sysfs_ops	= &class_dev_sysfs_ops,
	.release	= class_dev_release,
};

static int class_uevent_filter(struct kset *kset, struct kobject *kobj)
{
	struct kobj_type *ktype = get_ktype(kobj);

	if (ktype == &class_device_ktype) {
		struct class_device *class_dev = to_class_dev(kobj);
		if (class_dev->class)
			return 1;
	}
	return 0;
}

static const char *class_uevent_name(struct kset *kset, struct kobject *kobj)
{
	struct class_device *class_dev = to_class_dev(kobj);

	return class_dev->class->name;
}

#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;
}

static int make_deprecated_class_device_links(struct class_device *class_dev)
{
	char *class_name;
	int error;

	if (!class_dev->dev)
		return 0;

	class_name = make_class_name(class_dev->class->name, &class_dev->kobj);
	if (class_name)
		error = sysfs_create_link(&class_dev->dev->kobj,
					  &class_dev->kobj, class_name);
	else
		error = -ENOMEM;
	kfree(class_name);
	return error;
}

static void remove_deprecated_class_device_links(struct class_device *class_dev)
{
	char *class_name;

	if (!class_dev->dev)
		return;

	class_name = make_class_name(class_dev->class->name, &class_dev->kobj);
	if (class_name)
		sysfs_remove_link(&class_dev->dev->kobj, class_name);
	kfree(class_name);
}
#else
static inline int make_deprecated_class_device_links(struct class_device *cd)
{ return 0; }
static void remove_deprecated_class_device_links(struct class_device *cd)
{ }
#endif

static int class_uevent(struct kset *kset, struct kobject *kobj,
			struct kobj_uevent_env *env)
{
	struct class_device *class_dev = to_class_dev(kobj);
	struct device *dev = class_dev->dev;
	int retval = 0;

	pr_debug("%s - name = %s\n", __FUNCTION__, class_dev->class_id);

	if (MAJOR(class_dev->devt)) {
		add_uevent_var(env, "MAJOR=%u", MAJOR(class_dev->devt));

		add_uevent_var(env, "MINOR=%u", MINOR(class_dev->devt));
	}

	if (dev) {
		const char *path = kobject_get_path(&dev->kobj, GFP_KERNEL);
		if (path) {
			add_uevent_var(env, "PHYSDEVPATH=%s", path);
			kfree(path);
		}

		if (dev->bus)
			add_uevent_var(env, "PHYSDEVBUS=%s", dev->bus->name);

		if (dev->driver)
			add_uevent_var(env, "PHYSDEVDRIVER=%s", dev->driver->name);
	}

	if (class_dev->uevent) {
		/* have the class device specific function add its stuff */
		retval = class_dev->uevent(class_dev, env);
		if (retval)
			pr_debug("class_dev->uevent() returned %d\n", retval);
	} else if (class_dev->class->uevent) {
		/* have the class specific function add its stuff */
		retval = class_dev->class->uevent(class_dev, env);
		if (retval)
			pr_debug("class->uevent() returned %d\n", retval);
	}

	return retval;
}