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diff --git a/include/linux/device/class.h b/include/linux/device/class.h
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+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The class-specific portions of the driver model
+ *
+ * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
+ * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
+ * Copyright (c) 2008-2009 Novell Inc.
+ * Copyright (c) 2012-2019 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+ * Copyright (c) 2012-2019 Linux Foundation
+ *
+ * See Documentation/driver-api/driver-model/ for more information.
+ */
+
+#ifndef _DEVICE_CLASS_H_
+#define _DEVICE_CLASS_H_
+
+#include <linux/kobject.h>
+#include <linux/klist.h>
+#include <linux/pm.h>
+#include <linux/device/bus.h>
+
+struct device;
+struct fwnode_handle;
+
+/**
+ * struct class - device classes
+ * @name: Name of the class.
+ * @owner: The module owner.
+ * @class_groups: Default attributes of this class.
+ * @dev_groups: Default attributes of the devices that belong to the class.
+ * @dev_kobj: The kobject that represents this class and links it into the hierarchy.
+ * @dev_uevent: Called when a device is added, removed from this class, or a
+ * few other things that generate uevents to add the environment
+ * variables.
+ * @devnode: Callback to provide the devtmpfs.
+ * @class_release: Called to release this class.
+ * @dev_release: Called to release the device.
+ * @shutdown_pre: Called at shut-down time before driver shutdown.
+ * @ns_type: Callbacks so sysfs can detemine namespaces.
+ * @namespace: Namespace of the device belongs to this class.
+ * @get_ownership: Allows class to specify uid/gid of the sysfs directories
+ * for the devices belonging to the class. Usually tied to
+ * device's namespace.
+ * @pm: The default device power management operations of this class.
+ * @p: The private data of the driver core, no one other than the
+ * driver core can touch this.
+ *
+ * A class is a higher-level view of a device that abstracts out low-level
+ * implementation details. Drivers may see a SCSI disk or an ATA disk, but,
+ * at the class level, they are all simply disks. Classes allow user space
+ * to work with devices based on what they do, rather than how they are
+ * connected or how they work.
+ */
+struct class {
+ const char *name;
+ struct module *owner;
+
+ const struct attribute_group **class_groups;
+ const struct attribute_group **dev_groups;
+ struct kobject *dev_kobj;
+
+ int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
+ char *(*devnode)(struct device *dev, umode_t *mode);
+
+ void (*class_release)(struct class *class);
+ void (*dev_release)(struct device *dev);
+
+ int (*shutdown_pre)(struct device *dev);
+
+ const struct kobj_ns_type_operations *ns_type;
+ const void *(*namespace)(struct device *dev);
+
+ void (*get_ownership)(struct device *dev, kuid_t *uid, kgid_t *gid);
+
+ const struct dev_pm_ops *pm;
+
+ struct subsys_private *p;
+};
+
+struct class_dev_iter {
+ struct klist_iter ki;
+ const struct device_type *type;
+};
+
+extern struct kobject *sysfs_dev_block_kobj;
+extern struct kobject *sysfs_dev_char_kobj;
+extern int __must_check __class_register(struct class *class,
+ struct lock_class_key *key);
+extern void class_unregister(struct class *class);
+
+/* This is a #define to keep the compiler from merging different
+ * instances of the __key variable */
+#define class_register(class) \
+({ \
+ static struct lock_class_key __key; \
+ __class_register(class, &__key); \
+})
+
+struct class_compat;
+struct class_compat *class_compat_register(const char *name);
+void class_compat_unregister(struct class_compat *cls);
+int class_compat_create_link(struct class_compat *cls, struct device *dev,
+ struct device *device_link);
+void class_compat_remove_link(struct class_compat *cls, struct device *dev,
+ struct device *device_link);
+
+extern void class_dev_iter_init(struct class_dev_iter *iter,
+ struct class *class,
+ struct device *start,
+ const struct device_type *type);
+extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
+extern void class_dev_iter_exit(struct class_dev_iter *iter);
+
+extern int class_for_each_device(struct class *class, struct device *start,
+ void *data,
+ int (*fn)(struct device *dev, void *data));
+extern struct device *class_find_device(struct class *class,
+ struct device *start, const void *data,
+ int (*match)(struct device *, const void *));
+
+/**
+ * class_find_device_by_name - device iterator for locating a particular device
+ * of a specific name.
+ * @class: class type
+ * @name: name of the device to match
+ */
+static inline struct device *class_find_device_by_name(struct class *class,
+ const char *name)
+{
+ return class_find_device(class, NULL, name, device_match_name);
+}
+
+/**
+ * class_find_device_by_of_node : device iterator for locating a particular device
+ * matching the of_node.
+ * @class: class type
+ * @np: of_node of the device to match.
+ */
+static inline struct device *
+class_find_device_by_of_node(struct class *class, const struct device_node *np)
+{
+ return class_find_device(class, NULL, np, device_match_of_node);
+}
+
+/**
+ * class_find_device_by_fwnode : device iterator for locating a particular device
+ * matching the fwnode.
+ * @class: class type
+ * @fwnode: fwnode of the device to match.
+ */
+static inline struct device *
+class_find_device_by_fwnode(struct class *class,
+ const struct fwnode_handle *fwnode)
+{
+ return class_find_device(class, NULL, fwnode, device_match_fwnode);
+}
+
+/**
+ * class_find_device_by_devt : device iterator for locating a particular device
+ * matching the device type.
+ * @class: class type
+ * @devt: device type of the device to match.
+ */
+static inline struct device *class_find_device_by_devt(struct class *class,
+ dev_t devt)
+{
+ return class_find_device(class, NULL, &devt, device_match_devt);
+}
+
+#ifdef CONFIG_ACPI
+struct acpi_device;
+/**
+ * class_find_device_by_acpi_dev : device iterator for locating a particular
+ * device matching the ACPI_COMPANION device.
+ * @class: class type
+ * @adev: ACPI_COMPANION device to match.
+ */
+static inline struct device *
+class_find_device_by_acpi_dev(struct class *class, const struct acpi_device *adev)
+{
+ return class_find_device(class, NULL, adev, device_match_acpi_dev);
+}
+#else
+static inline struct device *
+class_find_device_by_acpi_dev(struct class *class, const void *adev)
+{
+ return NULL;
+}
+#endif
+
+struct class_attribute {
+ struct attribute attr;
+ ssize_t (*show)(struct class *class, struct class_attribute *attr,
+ char *buf);
+ ssize_t (*store)(struct class *class, struct class_attribute *attr,
+ const char *buf, size_t count);
+};
+
+#define CLASS_ATTR_RW(_name) \
+ struct class_attribute class_attr_##_name = __ATTR_RW(_name)
+#define CLASS_ATTR_RO(_name) \
+ struct class_attribute class_attr_##_name = __ATTR_RO(_name)
+#define CLASS_ATTR_WO(_name) \
+ struct class_attribute class_attr_##_name = __ATTR_WO(_name)
+
+extern int __must_check class_create_file_ns(struct class *class,
+ const struct class_attribute *attr,
+ const void *ns);
+extern void class_remove_file_ns(struct class *class,
+ const struct class_attribute *attr,
+ const void *ns);
+
+static inline int __must_check class_create_file(struct class *class,
+ const struct class_attribute *attr)
+{
+ return class_create_file_ns(class, attr, NULL);
+}
+
+static inline void class_remove_file(struct class *class,
+ const struct class_attribute *attr)
+{
+ return class_remove_file_ns(class, attr, NULL);
+}
+
+/* Simple class attribute that is just a static string */
+struct class_attribute_string {
+ struct class_attribute attr;
+ char *str;
+};
+
+/* Currently read-only only */
+#define _CLASS_ATTR_STRING(_name, _mode, _str) \
+ { __ATTR(_name, _mode, show_class_attr_string, NULL), _str }
+#define CLASS_ATTR_STRING(_name, _mode, _str) \
+ struct class_attribute_string class_attr_##_name = \
+ _CLASS_ATTR_STRING(_name, _mode, _str)
+
+extern ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
+ char *buf);
+
+struct class_interface {
+ struct list_head node;
+ struct class *class;
+
+ int (*add_dev) (struct device *, struct class_interface *);
+ void (*remove_dev) (struct device *, struct class_interface *);
+};
+
+extern int __must_check class_interface_register(struct class_interface *);
+extern void class_interface_unregister(struct class_interface *);
+
+extern struct class * __must_check __class_create(struct module *owner,
+ const char *name,
+ struct lock_class_key *key);
+extern void class_destroy(struct class *cls);
+
+/* This is a #define to keep the compiler from merging different
+ * instances of the __key variable */
+#define class_create(owner, name) \
+({ \
+ static struct lock_class_key __key; \
+ __class_create(owner, name, &__key); \
+})
+
+
+#endif /* _DEVICE_CLASS_H_ */