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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
Now that class_to_subsys() can be used to get access to the internal class private pointer, convert the remaining few places in class.c that were accessing the pointer directly to use class_to_subsys() instead. By doing this, the need for class_get() and class_put() goes away as no one actually tries to increment the class structures anymore, only the internal dynamic one. Cc: "Rafael J. Wysocki" <rafael@kernel.org> Link: https://lore.kernel.org/r/20230325194234.46588-2-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
643 lines
16 KiB
C
643 lines
16 KiB
C
// 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/blkdev.h>
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#include <linux/mutex.h>
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#include "base.h"
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/* /sys/class */
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static struct kset *class_kset;
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#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
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/**
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* class_to_subsys - Turn a struct class into a struct subsys_private
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*
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* @class: pointer to the struct bus_type to look up
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*
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* The driver core internals need to work on the subsys_private structure, not
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* the external struct class pointer. This function walks the list of
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* registered classes in the system and finds the matching one and returns the
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* internal struct subsys_private that relates to that class.
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*
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* Note, the reference count of the return value is INCREMENTED if it is not
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* NULL. A call to subsys_put() must be done when finished with the pointer in
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* order for it to be properly freed.
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*/
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static struct subsys_private *class_to_subsys(const struct class *class)
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{
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struct subsys_private *sp = NULL;
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struct kobject *kobj;
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if (!class || !class_kset)
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return NULL;
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spin_lock(&class_kset->list_lock);
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if (list_empty(&class_kset->list))
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goto done;
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list_for_each_entry(kobj, &class_kset->list, entry) {
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struct kset *kset = container_of(kobj, struct kset, kobj);
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sp = container_of_const(kset, struct subsys_private, subsys);
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if (sp->class == class)
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goto done;
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}
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sp = NULL;
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done:
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sp = subsys_get(sp);
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spin_unlock(&class_kset->list_lock);
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return sp;
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}
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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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class->p = NULL;
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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(const struct kobject *kobj)
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{
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const 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 const 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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int class_create_file_ns(const struct class *cls, const struct class_attribute *attr,
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const void *ns)
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{
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struct subsys_private *sp = class_to_subsys(cls);
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int error;
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if (!sp)
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return -EINVAL;
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error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns);
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subsys_put(sp);
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return error;
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}
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EXPORT_SYMBOL_GPL(class_create_file_ns);
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void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr,
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const void *ns)
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{
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struct subsys_private *sp = class_to_subsys(cls);
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if (!sp)
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return;
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sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);
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subsys_put(sp);
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}
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EXPORT_SYMBOL_GPL(class_remove_file_ns);
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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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int class_register(struct class *cls)
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{
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struct subsys_private *cp;
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struct lock_class_key *key;
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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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key = &cp->lock_key;
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lockdep_register_key(key);
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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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cp->subsys.kobj.kset = class_kset;
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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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goto err_out;
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error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups);
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if (error) {
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kobject_del(&cp->subsys.kobj);
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kfree_const(cp->subsys.kobj.name);
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goto err_out;
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}
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return 0;
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err_out:
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kfree(cp);
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cls->p = NULL;
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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(const struct class *cls)
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{
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struct subsys_private *sp = class_to_subsys(cls);
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if (!sp)
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return;
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pr_debug("device class '%s': unregistering\n", cls->name);
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sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups);
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kset_unregister(&sp->subsys);
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subsys_put(sp);
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}
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EXPORT_SYMBOL_GPL(class_unregister);
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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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* @name: pointer to a string for the name of this class.
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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(const char *name)
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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->class_release = class_create_release;
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retval = class_register(cls);
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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(const struct class *cls)
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{
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if (IS_ERR_OR_NULL(cls))
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return;
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class_unregister(cls);
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}
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EXPORT_SYMBOL_GPL(class_destroy);
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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, const struct class *class,
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const struct device *start, const struct device_type *type)
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{
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struct subsys_private *sp = class_to_subsys(class);
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struct klist_node *start_knode = NULL;
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if (!sp)
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return;
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if (start)
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start_knode = &start->p->knode_class;
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klist_iter_init_node(&sp->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(const struct class *class, const struct device *start,
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void *data, int (*fn)(struct device *, void *))
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{
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struct subsys_private *sp = class_to_subsys(class);
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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 (!sp) {
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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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subsys_put(sp);
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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(const struct class *class, const 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 subsys_private *sp = class_to_subsys(class);
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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 (!sp) {
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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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subsys_put(sp);
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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 subsys_private *sp;
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const 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_intf->class;
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sp = class_to_subsys(parent);
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if (!sp)
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return -EINVAL;
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/*
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* Reference in sp is now incremented and will be dropped when
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* the interface is removed in the call to class_interface_unregister()
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*/
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mutex_lock(&sp->mutex);
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list_add_tail(&class_intf->node, &sp->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(&sp->mutex);
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return 0;
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}
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EXPORT_SYMBOL_GPL(class_interface_register);
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void class_interface_unregister(struct class_interface *class_intf)
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{
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struct subsys_private *sp;
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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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sp = class_to_subsys(parent);
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if (!sp)
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return;
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mutex_lock(&sp->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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}
|
|
mutex_unlock(&sp->mutex);
|
|
|
|
/*
|
|
* Decrement the reference count twice, once for the class_to_subsys()
|
|
* call in the start of this function, and the second one from the
|
|
* reference increment in class_interface_register()
|
|
*/
|
|
subsys_put(sp);
|
|
subsys_put(sp);
|
|
}
|
|
EXPORT_SYMBOL_GPL(class_interface_unregister);
|
|
|
|
ssize_t show_class_attr_string(const struct class *class,
|
|
const struct class_attribute *attr, char *buf)
|
|
{
|
|
struct class_attribute_string *cs;
|
|
|
|
cs = container_of(attr, struct class_attribute_string, attr);
|
|
return sysfs_emit(buf, "%s\n", cs->str);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(show_class_attr_string);
|
|
|
|
struct class_compat {
|
|
struct kobject *kobj;
|
|
};
|
|
|
|
/**
|
|
* class_compat_register - register a compatibility class
|
|
* @name: the name of the class
|
|
*
|
|
* Compatibility class are meant as a temporary user-space compatibility
|
|
* workaround when converting a family of class devices to a bus devices.
|
|
*/
|
|
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);
|
|
|
|
/**
|
|
* class_compat_unregister - unregister a compatibility class
|
|
* @cls: the class to unregister
|
|
*/
|
|
void class_compat_unregister(struct class_compat *cls)
|
|
{
|
|
kobject_put(cls->kobj);
|
|
kfree(cls);
|
|
}
|
|
EXPORT_SYMBOL_GPL(class_compat_unregister);
|
|
|
|
/**
|
|
* class_compat_create_link - create a compatibility class device link to
|
|
* a bus device
|
|
* @cls: the compatibility class
|
|
* @dev: the target bus device
|
|
* @device_link: an optional device to which a "device" link should be created
|
|
*/
|
|
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);
|
|
|
|
/**
|
|
* class_compat_remove_link - remove a compatibility class device link to
|
|
* a bus device
|
|
* @cls: the compatibility class
|
|
* @dev: the target bus device
|
|
* @device_link: an optional device to which a "device" link was previously
|
|
* created
|
|
*/
|
|
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;
|
|
}
|