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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (c) 2025 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
4 * Copyright (c) 2025 The Linux Foundation
5 *
6 * A "simple" faux bus that allows devices to be created and added
7 * automatically to it. This is to be used whenever you need to create a
8 * device that is not associated with any "real" system resources, and do
9 * not want to have to deal with a bus/driver binding logic. It is
10 * intended to be very simple, with only a create and a destroy function
11 * available.
12 */
13#ifndef _FAUX_DEVICE_H_
14#define _FAUX_DEVICE_H_
15
16#include <linux/container_of.h>
17#include <linux/device.h>
18
19/**
20 * struct faux_device - a "faux" device
21 * @dev: internal struct device of the object
22 *
23 * A simple faux device that can be created/destroyed. To be used when a
24 * driver only needs to have a device to "hang" something off. This can be
25 * used for downloading firmware or other basic tasks. Use this instead of
26 * a struct platform_device if the device has no resources assigned to
27 * it at all.
28 */
29struct faux_device {
30 struct device dev;
31};
32#define to_faux_device(x) container_of_const((x), struct faux_device, dev)
33
34/**
35 * struct faux_device_ops - a set of callbacks for a struct faux_device
36 * @probe: called when a faux device is probed by the driver core
37 * before the device is fully bound to the internal faux bus
38 * code. If probe succeeds, return 0, otherwise return a
39 * negative error number to stop the probe sequence from
40 * succeeding.
41 * @remove: called when a faux device is removed from the system
42 *
43 * Both @probe and @remove are optional, if not needed, set to NULL.
44 */
45struct faux_device_ops {
46 int (*probe)(struct faux_device *faux_dev);
47 void (*remove)(struct faux_device *faux_dev);
48};
49
50struct faux_device *faux_device_create(const char *name,
51 struct device *parent,
52 const struct faux_device_ops *faux_ops);
53struct faux_device *faux_device_create_with_groups(const char *name,
54 struct device *parent,
55 const struct faux_device_ops *faux_ops,
56 const struct attribute_group **groups);
57void faux_device_destroy(struct faux_device *faux_dev);
58
59static inline void *faux_device_get_drvdata(const struct faux_device *faux_dev)
60{
61 return dev_get_drvdata(&faux_dev->dev);
62}
63
64static inline void faux_device_set_drvdata(struct faux_device *faux_dev, void *data)
65{
66 dev_set_drvdata(&faux_dev->dev, data);
67}
68
69#endif /* _FAUX_DEVICE_H_ */