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41 results

class.c

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    Greg Kroah-Hartman authored
    This renames the struct class "devices" field to be "class_devices" to
    make things easier when struct bus_type and struct class merge in the
    future.  It also makes grepping for fields easier as well.
    
    Based on an idea from Kay.
    
    Cc: Kay Sievers <kay.sievers@vrfy.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    97ae69fd
    History
    class.c 9.64 KiB
    /*
     * 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)
    
    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_private *cp = to_class(kobj);
    	ssize_t ret = -EIO;
    
    	if (class_attr->show)
    		ret = class_attr->show(cp->class, 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_private *cp = to_class(kobj);
    	ssize_t ret = -EIO;
    
    	if (class_attr->store)
    		ret = class_attr->store(cp->class, buf, count);
    	return ret;
    }
    
    static void class_release(struct kobject *kobj)
    {
    	struct class_private *cp = to_class(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);
    }
    
    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->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]);
    	}
    }
    
    int class_register(struct class *cls)
    {
    	struct class_private *cp;
    	int error;
    
    	pr_debug("device class '%s': registering\n", cls->name);
    
    	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
    	if (!cp)
    		return -ENOMEM;
    	INIT_LIST_HEAD(&cp->class_devices);
    	INIT_LIST_HEAD(&cp->interfaces);
    	kset_init(&cp->class_dirs);
    	init_MUTEX(&cp->sem);
    	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_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
    	/* let the block class directory show up in the root of sysfs */
    	if (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;
    }
    
    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);
    }
    
    /**
     * 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->p->sem);
    	list_for_each_entry(dev, &class->p->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->p->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->p->sem);
    	list_for_each_entry(dev, &class->p->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->p->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->p->sem);
    	list_add_tail(&class_intf->node, &parent->p->interfaces);
    	if (class_intf->add_dev) {
    		list_for_each_entry(dev, &parent->p->class_devices, node)
    			class_intf->add_dev(dev, class_intf);
    	}
    	up(&parent->p->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->p->sem);
    	list_del_init(&class_intf->node);
    	if (class_intf->remove_dev) {
    		list_for_each_entry(dev, &parent->p->class_devices, node)
    			class_intf->remove_dev(dev, class_intf);
    	}
    	up(&parent->p->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);