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587 lines
15 KiB
587 lines
15 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* class.c - basic device class management |
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* |
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* Copyright (c) 2002-3 Patrick Mochel |
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* Copyright (c) 2002-3 Open Source Development Labs |
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* Copyright (c) 2003-2004 Greg Kroah-Hartman |
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* Copyright (c) 2003-2004 IBM Corp. |
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*/ |
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#include <linux/device/class.h> |
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#include <linux/device.h> |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/string.h> |
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#include <linux/kdev_t.h> |
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#include <linux/err.h> |
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#include <linux/slab.h> |
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#include <linux/genhd.h> |
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#include <linux/mutex.h> |
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#include "base.h" |
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#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr) |
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static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr, |
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char *buf) |
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{ |
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struct class_attribute *class_attr = to_class_attr(attr); |
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struct subsys_private *cp = to_subsys_private(kobj); |
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ssize_t ret = -EIO; |
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if (class_attr->show) |
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ret = class_attr->show(cp->class, class_attr, buf); |
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return ret; |
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} |
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static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr, |
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const char *buf, size_t count) |
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{ |
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struct class_attribute *class_attr = to_class_attr(attr); |
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struct subsys_private *cp = to_subsys_private(kobj); |
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ssize_t ret = -EIO; |
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if (class_attr->store) |
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ret = class_attr->store(cp->class, class_attr, buf, count); |
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return ret; |
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} |
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static void class_release(struct kobject *kobj) |
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{ |
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struct subsys_private *cp = to_subsys_private(kobj); |
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struct class *class = cp->class; |
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pr_debug("class '%s': release.\n", class->name); |
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if (class->class_release) |
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class->class_release(class); |
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else |
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pr_debug("class '%s' does not have a release() function, " |
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"be careful\n", class->name); |
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kfree(cp); |
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} |
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static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj) |
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{ |
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struct subsys_private *cp = to_subsys_private(kobj); |
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struct class *class = cp->class; |
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return class->ns_type; |
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} |
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static const struct sysfs_ops class_sysfs_ops = { |
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.show = class_attr_show, |
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.store = class_attr_store, |
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}; |
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static struct kobj_type class_ktype = { |
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.sysfs_ops = &class_sysfs_ops, |
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.release = class_release, |
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.child_ns_type = class_child_ns_type, |
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}; |
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/* Hotplug events for classes go to the class subsys */ |
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static struct kset *class_kset; |
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int class_create_file_ns(struct class *cls, const struct class_attribute *attr, |
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const void *ns) |
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{ |
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int error; |
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if (cls) |
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error = sysfs_create_file_ns(&cls->p->subsys.kobj, |
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&attr->attr, ns); |
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else |
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error = -EINVAL; |
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return error; |
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} |
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void class_remove_file_ns(struct class *cls, const struct class_attribute *attr, |
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const void *ns) |
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{ |
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if (cls) |
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sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns); |
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} |
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static struct class *class_get(struct class *cls) |
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{ |
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if (cls) |
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kset_get(&cls->p->subsys); |
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return cls; |
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} |
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static void class_put(struct class *cls) |
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{ |
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if (cls) |
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kset_put(&cls->p->subsys); |
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} |
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static struct device *klist_class_to_dev(struct klist_node *n) |
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{ |
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struct device_private *p = to_device_private_class(n); |
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return p->device; |
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} |
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static void klist_class_dev_get(struct klist_node *n) |
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{ |
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struct device *dev = klist_class_to_dev(n); |
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get_device(dev); |
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} |
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static void klist_class_dev_put(struct klist_node *n) |
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{ |
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struct device *dev = klist_class_to_dev(n); |
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put_device(dev); |
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} |
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static int class_add_groups(struct class *cls, |
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const struct attribute_group **groups) |
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{ |
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return sysfs_create_groups(&cls->p->subsys.kobj, groups); |
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} |
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static void class_remove_groups(struct class *cls, |
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const struct attribute_group **groups) |
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{ |
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return sysfs_remove_groups(&cls->p->subsys.kobj, groups); |
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} |
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int __class_register(struct class *cls, struct lock_class_key *key) |
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{ |
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struct subsys_private *cp; |
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int error; |
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pr_debug("device class '%s': registering\n", cls->name); |
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cp = kzalloc(sizeof(*cp), GFP_KERNEL); |
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if (!cp) |
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return -ENOMEM; |
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klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put); |
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INIT_LIST_HEAD(&cp->interfaces); |
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kset_init(&cp->glue_dirs); |
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__mutex_init(&cp->mutex, "subsys mutex", key); |
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error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name); |
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if (error) { |
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kfree(cp); |
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return error; |
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} |
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/* set the default /sys/dev directory for devices of this class */ |
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if (!cls->dev_kobj) |
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cls->dev_kobj = sysfs_dev_char_kobj; |
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#if defined(CONFIG_BLOCK) |
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/* let the block class directory show up in the root of sysfs */ |
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if (!sysfs_deprecated || cls != &block_class) |
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cp->subsys.kobj.kset = class_kset; |
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#else |
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cp->subsys.kobj.kset = class_kset; |
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#endif |
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cp->subsys.kobj.ktype = &class_ktype; |
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cp->class = cls; |
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cls->p = cp; |
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error = kset_register(&cp->subsys); |
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if (error) { |
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kfree(cp); |
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return error; |
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} |
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error = class_add_groups(class_get(cls), cls->class_groups); |
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class_put(cls); |
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return error; |
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} |
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EXPORT_SYMBOL_GPL(__class_register); |
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void class_unregister(struct class *cls) |
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{ |
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pr_debug("device class '%s': unregistering\n", cls->name); |
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class_remove_groups(cls, cls->class_groups); |
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kset_unregister(&cls->p->subsys); |
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} |
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static void class_create_release(struct class *cls) |
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{ |
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pr_debug("%s called for %s\n", __func__, cls->name); |
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kfree(cls); |
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} |
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/** |
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* __class_create - create a struct class structure |
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* @owner: pointer to the module that is to "own" this struct class |
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* @name: pointer to a string for the name of this class. |
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* @key: the lock_class_key for this class; used by mutex lock debugging |
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* |
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* This is used to create a struct class pointer that can then be used |
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* in calls to device_create(). |
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* |
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* Returns &struct class pointer on success, or ERR_PTR() on error. |
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* |
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* Note, the pointer created here is to be destroyed when finished by |
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* making a call to class_destroy(). |
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*/ |
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struct class *__class_create(struct module *owner, const char *name, |
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struct lock_class_key *key) |
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{ |
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struct class *cls; |
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int retval; |
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cls = kzalloc(sizeof(*cls), GFP_KERNEL); |
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if (!cls) { |
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retval = -ENOMEM; |
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goto error; |
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} |
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cls->name = name; |
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cls->owner = owner; |
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cls->class_release = class_create_release; |
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retval = __class_register(cls, key); |
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if (retval) |
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goto error; |
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return cls; |
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error: |
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kfree(cls); |
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return ERR_PTR(retval); |
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} |
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EXPORT_SYMBOL_GPL(__class_create); |
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/** |
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* class_destroy - destroys a struct class structure |
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* @cls: pointer to the struct class that is to be destroyed |
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* |
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* Note, the pointer to be destroyed must have been created with a call |
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* to class_create(). |
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*/ |
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void class_destroy(struct class *cls) |
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{ |
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if ((cls == NULL) || (IS_ERR(cls))) |
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return; |
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class_unregister(cls); |
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} |
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/** |
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* class_dev_iter_init - initialize class device iterator |
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* @iter: class iterator to initialize |
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* @class: the class we wanna iterate over |
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* @start: the device to start iterating from, if any |
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* @type: device_type of the devices to iterate over, NULL for all |
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* |
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* Initialize class iterator @iter such that it iterates over devices |
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* of @class. If @start is set, the list iteration will start there, |
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* otherwise if it is NULL, the iteration starts at the beginning of |
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* the list. |
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*/ |
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void class_dev_iter_init(struct class_dev_iter *iter, struct class *class, |
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struct device *start, const struct device_type *type) |
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{ |
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struct klist_node *start_knode = NULL; |
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if (start) |
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start_knode = &start->p->knode_class; |
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klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode); |
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iter->type = type; |
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} |
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EXPORT_SYMBOL_GPL(class_dev_iter_init); |
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/** |
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* class_dev_iter_next - iterate to the next device |
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* @iter: class iterator to proceed |
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* |
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* Proceed @iter to the next device and return it. Returns NULL if |
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* iteration is complete. |
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* |
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* The returned device is referenced and won't be released till |
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* iterator is proceed to the next device or exited. The caller is |
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* free to do whatever it wants to do with the device including |
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* calling back into class code. |
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*/ |
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struct device *class_dev_iter_next(struct class_dev_iter *iter) |
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{ |
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struct klist_node *knode; |
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struct device *dev; |
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while (1) { |
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knode = klist_next(&iter->ki); |
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if (!knode) |
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return NULL; |
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dev = klist_class_to_dev(knode); |
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if (!iter->type || iter->type == dev->type) |
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return dev; |
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} |
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} |
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EXPORT_SYMBOL_GPL(class_dev_iter_next); |
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/** |
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* class_dev_iter_exit - finish iteration |
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* @iter: class iterator to finish |
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* |
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* Finish an iteration. Always call this function after iteration is |
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* complete whether the iteration ran till the end or not. |
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*/ |
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void class_dev_iter_exit(struct class_dev_iter *iter) |
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{ |
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klist_iter_exit(&iter->ki); |
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} |
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EXPORT_SYMBOL_GPL(class_dev_iter_exit); |
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/** |
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* class_for_each_device - device iterator |
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* @class: the class we're iterating |
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* @start: the device to start with in the list, if any. |
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* @data: data for the callback |
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* @fn: function to be called for each device |
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* |
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* Iterate over @class's list of devices, and call @fn for each, |
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* passing it @data. If @start is set, the list iteration will start |
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* there, otherwise if it is NULL, the iteration starts at the |
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* beginning of the list. |
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* |
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* We check the return of @fn each time. If it returns anything |
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* other than 0, we break out and return that value. |
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* |
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* @fn is allowed to do anything including calling back into class |
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* code. There's no locking restriction. |
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*/ |
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int class_for_each_device(struct class *class, struct device *start, |
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void *data, int (*fn)(struct device *, void *)) |
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{ |
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struct class_dev_iter iter; |
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struct device *dev; |
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int error = 0; |
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if (!class) |
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return -EINVAL; |
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if (!class->p) { |
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WARN(1, "%s called for class '%s' before it was initialized", |
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__func__, class->name); |
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return -EINVAL; |
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} |
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class_dev_iter_init(&iter, class, start, NULL); |
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while ((dev = class_dev_iter_next(&iter))) { |
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error = fn(dev, data); |
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if (error) |
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break; |
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} |
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class_dev_iter_exit(&iter); |
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return error; |
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} |
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EXPORT_SYMBOL_GPL(class_for_each_device); |
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/** |
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* class_find_device - device iterator for locating a particular device |
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* @class: the class we're iterating |
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* @start: Device to begin with |
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* @data: data for the match function |
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* @match: function to check device |
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* |
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* This is similar to the class_for_each_dev() function above, but it |
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* returns a reference to a device that is 'found' for later use, as |
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* determined by the @match callback. |
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* |
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* The callback should return 0 if the device doesn't match and non-zero |
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* if it does. If the callback returns non-zero, this function will |
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* return to the caller and not iterate over any more devices. |
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* |
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* Note, you will need to drop the reference with put_device() after use. |
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* |
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* @match is allowed to do anything including calling back into class |
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* code. There's no locking restriction. |
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*/ |
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struct device *class_find_device(struct class *class, struct device *start, |
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const void *data, |
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int (*match)(struct device *, const void *)) |
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{ |
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struct class_dev_iter iter; |
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struct device *dev; |
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if (!class) |
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return NULL; |
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if (!class->p) { |
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WARN(1, "%s called for class '%s' before it was initialized", |
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__func__, class->name); |
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return NULL; |
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} |
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class_dev_iter_init(&iter, class, start, NULL); |
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while ((dev = class_dev_iter_next(&iter))) { |
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if (match(dev, data)) { |
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get_device(dev); |
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break; |
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} |
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} |
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class_dev_iter_exit(&iter); |
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return dev; |
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} |
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EXPORT_SYMBOL_GPL(class_find_device); |
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int class_interface_register(struct class_interface *class_intf) |
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{ |
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struct class *parent; |
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struct class_dev_iter iter; |
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struct device *dev; |
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if (!class_intf || !class_intf->class) |
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return -ENODEV; |
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parent = class_get(class_intf->class); |
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if (!parent) |
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return -EINVAL; |
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mutex_lock(&parent->p->mutex); |
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list_add_tail(&class_intf->node, &parent->p->interfaces); |
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if (class_intf->add_dev) { |
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class_dev_iter_init(&iter, parent, NULL, NULL); |
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while ((dev = class_dev_iter_next(&iter))) |
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class_intf->add_dev(dev, class_intf); |
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class_dev_iter_exit(&iter); |
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} |
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mutex_unlock(&parent->p->mutex); |
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return 0; |
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} |
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void class_interface_unregister(struct class_interface *class_intf) |
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{ |
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struct class *parent = class_intf->class; |
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struct class_dev_iter iter; |
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struct device *dev; |
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if (!parent) |
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return; |
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mutex_lock(&parent->p->mutex); |
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list_del_init(&class_intf->node); |
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if (class_intf->remove_dev) { |
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class_dev_iter_init(&iter, parent, NULL, NULL); |
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while ((dev = class_dev_iter_next(&iter))) |
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class_intf->remove_dev(dev, class_intf); |
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class_dev_iter_exit(&iter); |
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} |
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mutex_unlock(&parent->p->mutex); |
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class_put(parent); |
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} |
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ssize_t show_class_attr_string(struct class *class, |
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struct class_attribute *attr, char *buf) |
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{ |
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struct class_attribute_string *cs; |
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cs = container_of(attr, struct class_attribute_string, attr); |
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return sysfs_emit(buf, "%s\n", cs->str); |
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} |
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EXPORT_SYMBOL_GPL(show_class_attr_string); |
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struct class_compat { |
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struct kobject *kobj; |
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}; |
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/** |
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* class_compat_register - register a compatibility class |
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* @name: the name of the class |
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* |
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* Compatibility class are meant as a temporary user-space compatibility |
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* workaround when converting a family of class devices to a bus devices. |
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*/ |
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struct class_compat *class_compat_register(const char *name) |
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{ |
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struct class_compat *cls; |
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cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL); |
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if (!cls) |
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return NULL; |
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cls->kobj = kobject_create_and_add(name, &class_kset->kobj); |
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if (!cls->kobj) { |
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kfree(cls); |
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return NULL; |
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} |
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return cls; |
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} |
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EXPORT_SYMBOL_GPL(class_compat_register); |
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/** |
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* class_compat_unregister - unregister a compatibility class |
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* @cls: the class to unregister |
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*/ |
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void class_compat_unregister(struct class_compat *cls) |
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{ |
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kobject_put(cls->kobj); |
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kfree(cls); |
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} |
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EXPORT_SYMBOL_GPL(class_compat_unregister); |
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/** |
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* class_compat_create_link - create a compatibility class device link to |
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* a bus device |
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* @cls: the compatibility class |
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* @dev: the target bus device |
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* @device_link: an optional device to which a "device" link should be created |
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*/ |
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int class_compat_create_link(struct class_compat *cls, struct device *dev, |
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struct device *device_link) |
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{ |
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int error; |
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error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev)); |
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if (error) |
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return error; |
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/* |
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* Optionally add a "device" link (typically to the parent), as a |
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* class device would have one and we want to provide as much |
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* backwards compatibility as possible. |
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*/ |
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if (device_link) { |
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error = sysfs_create_link(&dev->kobj, &device_link->kobj, |
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"device"); |
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if (error) |
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sysfs_remove_link(cls->kobj, dev_name(dev)); |
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} |
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return error; |
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} |
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EXPORT_SYMBOL_GPL(class_compat_create_link); |
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/** |
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* class_compat_remove_link - remove a compatibility class device link to |
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* a bus device |
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* @cls: the compatibility class |
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* @dev: the target bus device |
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* @device_link: an optional device to which a "device" link was previously |
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* created |
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*/ |
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void class_compat_remove_link(struct class_compat *cls, struct device *dev, |
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struct device *device_link) |
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{ |
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if (device_link) |
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sysfs_remove_link(&dev->kobj, "device"); |
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sysfs_remove_link(cls->kobj, dev_name(dev)); |
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} |
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EXPORT_SYMBOL_GPL(class_compat_remove_link); |
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int __init classes_init(void) |
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{ |
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class_kset = kset_create_and_add("class", NULL, NULL); |
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if (!class_kset) |
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return -ENOMEM; |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(class_create_file_ns); |
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EXPORT_SYMBOL_GPL(class_remove_file_ns); |
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EXPORT_SYMBOL_GPL(class_unregister); |
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EXPORT_SYMBOL_GPL(class_destroy); |
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EXPORT_SYMBOL_GPL(class_interface_register); |
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EXPORT_SYMBOL_GPL(class_interface_unregister);
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