tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2023 Linaro Ltd.
4 *
5 * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
6 */
7#include <linux/auxiliary_bus.h>
8#include <linux/module.h>
9#include <linux/of.h>
10
11#include <drm/drm_bridge.h>
12#include <drm/bridge/aux-bridge.h>
13
14static DEFINE_IDA(drm_aux_bridge_ida);
15
16static void drm_aux_bridge_release(struct device *dev)
17{
18 struct auxiliary_device *adev = to_auxiliary_dev(dev);
19
20 ida_free(&drm_aux_bridge_ida, adev->id);
21
22 kfree(adev);
23}
24
25static void drm_aux_bridge_unregister_adev(void *_adev)
26{
27 struct auxiliary_device *adev = _adev;
28
29 auxiliary_device_delete(adev);
30 auxiliary_device_uninit(adev);
31}
32
33/**
34 * drm_aux_bridge_register - Create a simple bridge device to link the chain
35 * @parent: device instance providing this bridge
36 *
37 * Creates a simple DRM bridge that doesn't implement any drm_bridge
38 * operations. Such bridges merely fill a place in the bridge chain linking
39 * surrounding DRM bridges.
40 *
41 * Return: zero on success, negative error code on failure
42 */
43int drm_aux_bridge_register(struct device *parent)
44{
45 struct auxiliary_device *adev;
46 int ret;
47
48 adev = kzalloc(sizeof(*adev), GFP_KERNEL);
49 if (!adev)
50 return -ENOMEM;
51
52 ret = ida_alloc(&drm_aux_bridge_ida, GFP_KERNEL);
53 if (ret < 0) {
54 kfree(adev);
55 return ret;
56 }
57
58 adev->id = ret;
59 adev->name = "aux_bridge";
60 adev->dev.parent = parent;
61 adev->dev.of_node = of_node_get(parent->of_node);
62 adev->dev.release = drm_aux_bridge_release;
63
64 ret = auxiliary_device_init(adev);
65 if (ret) {
66 ida_free(&drm_aux_bridge_ida, adev->id);
67 kfree(adev);
68 return ret;
69 }
70
71 ret = auxiliary_device_add(adev);
72 if (ret) {
73 auxiliary_device_uninit(adev);
74 return ret;
75 }
76
77 return devm_add_action_or_reset(parent, drm_aux_bridge_unregister_adev, adev);
78}
79EXPORT_SYMBOL_GPL(drm_aux_bridge_register);
80
81struct drm_aux_bridge_data {
82 struct drm_bridge bridge;
83 struct drm_bridge *next_bridge;
84 struct device *dev;
85};
86
87static int drm_aux_bridge_attach(struct drm_bridge *bridge,
88 enum drm_bridge_attach_flags flags)
89{
90 struct drm_aux_bridge_data *data;
91
92 if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
93 return -EINVAL;
94
95 data = container_of(bridge, struct drm_aux_bridge_data, bridge);
96
97 return drm_bridge_attach(bridge->encoder, data->next_bridge, bridge,
98 DRM_BRIDGE_ATTACH_NO_CONNECTOR);
99}
100
101static const struct drm_bridge_funcs drm_aux_bridge_funcs = {
102 .attach = drm_aux_bridge_attach,
103};
104
105static int drm_aux_bridge_probe(struct auxiliary_device *auxdev,
106 const struct auxiliary_device_id *id)
107{
108 struct drm_aux_bridge_data *data;
109
110 data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
111 if (!data)
112 return -ENOMEM;
113
114 data->dev = &auxdev->dev;
115 data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);
116 if (IS_ERR(data->next_bridge))
117 return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),
118 "failed to acquire drm_bridge\n");
119
120 data->bridge.funcs = &drm_aux_bridge_funcs;
121 data->bridge.of_node = data->dev->of_node;
122
123 return devm_drm_bridge_add(data->dev, &data->bridge);
124}
125
126static const struct auxiliary_device_id drm_aux_bridge_table[] = {
127 { .name = KBUILD_MODNAME ".aux_bridge" },
128 {},
129};
130MODULE_DEVICE_TABLE(auxiliary, drm_aux_bridge_table);
131
132static struct auxiliary_driver drm_aux_bridge_drv = {
133 .name = "aux_bridge",
134 .id_table = drm_aux_bridge_table,
135 .probe = drm_aux_bridge_probe,
136};
137module_auxiliary_driver(drm_aux_bridge_drv);
138
139MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
140MODULE_DESCRIPTION("DRM transparent bridge");
141MODULE_LICENSE("GPL");