class.h

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * The class-specific portions of the driver model
  4 *
  5 * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
  6 * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
  7 * Copyright (c) 2008-2009 Novell Inc.
  8 * Copyright (c) 2012-2019 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  9 * Copyright (c) 2012-2019 Linux Foundation
 10 *
 11 * See Documentation/driver-api/driver-model/ for more information.
 12 */
 13
 14#ifndef _DEVICE_CLASS_H_
 15#define _DEVICE_CLASS_H_
 16
 17#include <linux/kobject.h>
 18#include <linux/klist.h>
 19#include <linux/pm.h>
 20#include <linux/device/bus.h>
 21
 22struct device;
 23struct fwnode_handle;
 24
 25/**
 26 * struct class - device classes
 27 * @name:	Name of the class.
 28 * @class_groups: Default attributes of this class.
 29 * @dev_groups:	Default attributes of the devices that belong to the class.
 30 * @dev_uevent:	Called when a device is added, removed from this class, or a
 31 *		few other things that generate uevents to add the environment
 32 *		variables.
 33 * @devnode:	Callback to provide the devtmpfs.
 34 * @class_release: Called to release this class.
 35 * @dev_release: Called to release the device.
 36 * @shutdown_pre: Called at shut-down time before driver shutdown.
 37 * @ns_type:	Callbacks so sysfs can detemine namespaces.
 38 * @namespace:	Namespace of the device belongs to this class.
 39 * @get_ownership: Allows class to specify uid/gid of the sysfs directories
 40 *		for the devices belonging to the class. Usually tied to
 41 *		device's namespace.
 42 * @pm:		The default device power management operations of this class.
 43 *
 44 * A class is a higher-level view of a device that abstracts out low-level
 45 * implementation details. Drivers may see a SCSI disk or an ATA disk, but,
 46 * at the class level, they are all simply disks. Classes allow user space
 47 * to work with devices based on what they do, rather than how they are
 48 * connected or how they work.
 49 */
 50struct class {
 51	const char		*name;
 52
 53	const struct attribute_group	**class_groups;
 54	const struct attribute_group	**dev_groups;
 55
 56	int (*dev_uevent)(const struct device *dev, struct kobj_uevent_env *env);
 57	char *(*devnode)(const struct device *dev, umode_t *mode);
 58
 59	void (*class_release)(const struct class *class);
 60	void (*dev_release)(struct device *dev);
 61
 62	int (*shutdown_pre)(struct device *dev);
 63
 64	const struct kobj_ns_type_operations *ns_type;
 65	const void *(*namespace)(const struct device *dev);
 66
 67	void (*get_ownership)(const struct device *dev, kuid_t *uid, kgid_t *gid);
 68
 69	const struct dev_pm_ops *pm;
 70};
 71
 72struct class_dev_iter {
 73	struct klist_iter		ki;
 74	const struct device_type	*type;
 75	struct subsys_private		*sp;
 76};
 77
 78int __must_check class_register(const struct class *class);
 79void class_unregister(const struct class *class);
 80bool class_is_registered(const struct class *class);
 81
 82struct class_compat;
 83struct class_compat *class_compat_register(const char *name);
 84void class_compat_unregister(struct class_compat *cls);
 85int class_compat_create_link(struct class_compat *cls, struct device *dev);
 86void class_compat_remove_link(struct class_compat *cls, struct device *dev);
 87
 88void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
 89			 const struct device *start, const struct device_type *type);
 90struct device *class_dev_iter_next(struct class_dev_iter *iter);
 91void class_dev_iter_exit(struct class_dev_iter *iter);
 92
 93int class_for_each_device(const struct class *class, const struct device *start,
 94			  void *data, device_iter_t fn);
 95struct device *class_find_device(const struct class *class, const struct device *start,
 96				 const void *data, device_match_t match);
 97
 98/**
 99 * class_find_device_by_name - device iterator for locating a particular device
100 * of a specific name.
101 * @class: class type
102 * @name: name of the device to match
103 */
104static inline struct device *class_find_device_by_name(const struct class *class,
105						       const char *name)
106{
107	return class_find_device(class, NULL, name, device_match_name);
108}
109
110/**
111 * class_find_device_by_of_node : device iterator for locating a particular device
112 * matching the of_node.
113 * @class: class type
114 * @np: of_node of the device to match.
115 */
116static inline struct device *class_find_device_by_of_node(const struct class *class,
117							  const struct device_node *np)
118{
119	return class_find_device(class, NULL, np, device_match_of_node);
120}
121
122/**
123 * class_find_device_by_fwnode : device iterator for locating a particular device
124 * matching the fwnode.
125 * @class: class type
126 * @fwnode: fwnode of the device to match.
127 */
128static inline struct device *class_find_device_by_fwnode(const struct class *class,
129							 const struct fwnode_handle *fwnode)
130{
131	return class_find_device(class, NULL, fwnode, device_match_fwnode);
132}
133
134/**
135 * class_find_device_by_devt : device iterator for locating a particular device
136 * matching the device type.
137 * @class: class type
138 * @devt: device type of the device to match.
139 */
140static inline struct device *class_find_device_by_devt(const struct class *class,
141						       dev_t devt)
142{
143	return class_find_device(class, NULL, &devt, device_match_devt);
144}
145
146#ifdef CONFIG_ACPI
147struct acpi_device;
148/**
149 * class_find_device_by_acpi_dev : device iterator for locating a particular
150 * device matching the ACPI_COMPANION device.
151 * @class: class type
152 * @adev: ACPI_COMPANION device to match.
153 */
154static inline struct device *class_find_device_by_acpi_dev(const struct class *class,
155							   const struct acpi_device *adev)
156{
157	return class_find_device(class, NULL, adev, device_match_acpi_dev);
158}
159#else
160static inline struct device *class_find_device_by_acpi_dev(const struct class *class,
161							   const void *adev)
162{
163	return NULL;
164}
165#endif
166
167struct class_attribute {
168	struct attribute attr;
169	ssize_t (*show)(const struct class *class, const struct class_attribute *attr,
170			char *buf);
171	ssize_t (*store)(const struct class *class, const struct class_attribute *attr,
172			 const char *buf, size_t count);
173};
174
175#define CLASS_ATTR_RW(_name) \
176	struct class_attribute class_attr_##_name = __ATTR_RW(_name)
177#define CLASS_ATTR_RO(_name) \
178	struct class_attribute class_attr_##_name = __ATTR_RO(_name)
179#define CLASS_ATTR_WO(_name) \
180	struct class_attribute class_attr_##_name = __ATTR_WO(_name)
181
182int __must_check class_create_file_ns(const struct class *class, const struct class_attribute *attr,
183				      const void *ns);
184void class_remove_file_ns(const struct class *class, const struct class_attribute *attr,
185			  const void *ns);
186
187static inline int __must_check class_create_file(const struct class *class,
188						 const struct class_attribute *attr)
189{
190	return class_create_file_ns(class, attr, NULL);
191}
192
193static inline void class_remove_file(const struct class *class,
194				     const struct class_attribute *attr)
195{
196	class_remove_file_ns(class, attr, NULL);
197}
198
199/* Simple class attribute that is just a static string */
200struct class_attribute_string {
201	struct class_attribute attr;
202	char *str;
203};
204
205/* Currently read-only only */
206#define _CLASS_ATTR_STRING(_name, _mode, _str) \
207	{ __ATTR(_name, _mode, show_class_attr_string, NULL), _str }
208#define CLASS_ATTR_STRING(_name, _mode, _str) \
209	struct class_attribute_string class_attr_##_name = \
210		_CLASS_ATTR_STRING(_name, _mode, _str)
211
212ssize_t show_class_attr_string(const struct class *class, const struct class_attribute *attr,
213			       char *buf);
214
215struct class_interface {
216	struct list_head	node;
217	const struct class	*class;
218
219	int (*add_dev)		(struct device *dev);
220	void (*remove_dev)	(struct device *dev);
221};
222
223int __must_check class_interface_register(struct class_interface *);
224void class_interface_unregister(struct class_interface *);
225
226struct class * __must_check class_create(const char *name);
227void class_destroy(const struct class *cls);
228
229#endif	/* _DEVICE_CLASS_H_ */