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/export.h>
9 #include <linux/module.h>
10 #include <linux/of.h>
11
12 #include <drm/drm_bridge.h>
13 #include <drm/bridge/aux-bridge.h>
14
15 static DEFINE_IDA(drm_aux_hpd_bridge_ida);
16
17 struct drm_aux_hpd_bridge_data {
18 struct drm_bridge bridge;
19 struct device *dev;
20 };
21
drm_aux_hpd_bridge_release(struct device * dev)22 static void drm_aux_hpd_bridge_release(struct device *dev)
23 {
24 struct auxiliary_device *adev = to_auxiliary_dev(dev);
25
26 ida_free(&drm_aux_hpd_bridge_ida, adev->id);
27
28 of_node_put(adev->dev.platform_data);
29 of_node_put(adev->dev.of_node);
30
31 kfree(adev);
32 }
33
drm_aux_hpd_bridge_free_adev(void * _adev)34 static void drm_aux_hpd_bridge_free_adev(void *_adev)
35 {
36 auxiliary_device_uninit(_adev);
37 }
38
39 /**
40 * devm_drm_dp_hpd_bridge_alloc - allocate a HPD DisplayPort bridge
41 * @parent: device instance providing this bridge
42 * @np: device node pointer corresponding to this bridge instance
43 *
44 * Creates a simple DRM bridge with the type set to
45 * DRM_MODE_CONNECTOR_DisplayPort, which terminates the bridge chain and is
46 * able to send the HPD events.
47 *
48 * Return: bridge auxiliary device pointer or an error pointer
49 */
devm_drm_dp_hpd_bridge_alloc(struct device * parent,struct device_node * np)50 struct auxiliary_device *devm_drm_dp_hpd_bridge_alloc(struct device *parent, struct device_node *np)
51 {
52 struct auxiliary_device *adev;
53 int ret;
54
55 adev = kzalloc(sizeof(*adev), GFP_KERNEL);
56 if (!adev)
57 return ERR_PTR(-ENOMEM);
58
59 ret = ida_alloc(&drm_aux_hpd_bridge_ida, GFP_KERNEL);
60 if (ret < 0) {
61 kfree(adev);
62 return ERR_PTR(ret);
63 }
64
65 adev->id = ret;
66 adev->name = "dp_hpd_bridge";
67 adev->dev.parent = parent;
68 adev->dev.release = drm_aux_hpd_bridge_release;
69 adev->dev.platform_data = of_node_get(np);
70
71 device_set_of_node_from_dev(&adev->dev, parent);
72
73 ret = auxiliary_device_init(adev);
74 if (ret) {
75 of_node_put(adev->dev.platform_data);
76 of_node_put(adev->dev.of_node);
77 ida_free(&drm_aux_hpd_bridge_ida, adev->id);
78 kfree(adev);
79 return ERR_PTR(ret);
80 }
81
82 ret = devm_add_action_or_reset(parent, drm_aux_hpd_bridge_free_adev, adev);
83 if (ret)
84 return ERR_PTR(ret);
85
86 return adev;
87 }
88 EXPORT_SYMBOL_GPL(devm_drm_dp_hpd_bridge_alloc);
89
drm_aux_hpd_bridge_del_adev(void * _adev)90 static void drm_aux_hpd_bridge_del_adev(void *_adev)
91 {
92 auxiliary_device_delete(_adev);
93 }
94
95 /**
96 * devm_drm_dp_hpd_bridge_add - register a HDP DisplayPort bridge
97 * @dev: struct device to tie registration lifetime to
98 * @adev: bridge auxiliary device to be registered
99 *
100 * Returns: zero on success or a negative errno
101 */
devm_drm_dp_hpd_bridge_add(struct device * dev,struct auxiliary_device * adev)102 int devm_drm_dp_hpd_bridge_add(struct device *dev, struct auxiliary_device *adev)
103 {
104 int ret;
105
106 ret = auxiliary_device_add(adev);
107 if (ret)
108 return ret;
109
110 return devm_add_action_or_reset(dev, drm_aux_hpd_bridge_del_adev, adev);
111 }
112 EXPORT_SYMBOL_GPL(devm_drm_dp_hpd_bridge_add);
113
114 /**
115 * drm_dp_hpd_bridge_register - allocate and register a HDP DisplayPort bridge
116 * @parent: device instance providing this bridge
117 * @np: device node pointer corresponding to this bridge instance
118 *
119 * Return: device instance that will handle created bridge or an error pointer
120 */
drm_dp_hpd_bridge_register(struct device * parent,struct device_node * np)121 struct device *drm_dp_hpd_bridge_register(struct device *parent, struct device_node *np)
122 {
123 struct auxiliary_device *adev;
124 int ret;
125
126 adev = devm_drm_dp_hpd_bridge_alloc(parent, np);
127 if (IS_ERR(adev))
128 return ERR_CAST(adev);
129
130 ret = devm_drm_dp_hpd_bridge_add(parent, adev);
131 if (ret)
132 return ERR_PTR(ret);
133
134 return &adev->dev;
135 }
136 EXPORT_SYMBOL_GPL(drm_dp_hpd_bridge_register);
137
138 /**
139 * drm_aux_hpd_bridge_notify - notify hot plug detection events
140 * @dev: device created for the HPD bridge
141 * @status: output connection status
142 *
143 * A wrapper around drm_bridge_hpd_notify() that is used to report hot plug
144 * detection events for bridges created via drm_dp_hpd_bridge_register().
145 *
146 * This function shall be called in a context that can sleep.
147 */
drm_aux_hpd_bridge_notify(struct device * dev,enum drm_connector_status status)148 void drm_aux_hpd_bridge_notify(struct device *dev, enum drm_connector_status status)
149 {
150 struct auxiliary_device *adev = to_auxiliary_dev(dev);
151 struct drm_aux_hpd_bridge_data *data = auxiliary_get_drvdata(adev);
152
153 if (!data)
154 return;
155
156 drm_bridge_hpd_notify(&data->bridge, status);
157 }
158 EXPORT_SYMBOL_GPL(drm_aux_hpd_bridge_notify);
159
drm_aux_hpd_bridge_attach(struct drm_bridge * bridge,struct drm_encoder * encoder,enum drm_bridge_attach_flags flags)160 static int drm_aux_hpd_bridge_attach(struct drm_bridge *bridge,
161 struct drm_encoder *encoder,
162 enum drm_bridge_attach_flags flags)
163 {
164 return flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR ? 0 : -EINVAL;
165 }
166
167 static const struct drm_bridge_funcs drm_aux_hpd_bridge_funcs = {
168 .attach = drm_aux_hpd_bridge_attach,
169 };
170
drm_aux_hpd_bridge_probe(struct auxiliary_device * auxdev,const struct auxiliary_device_id * id)171 static int drm_aux_hpd_bridge_probe(struct auxiliary_device *auxdev,
172 const struct auxiliary_device_id *id)
173 {
174 struct drm_aux_hpd_bridge_data *data;
175
176 data = devm_drm_bridge_alloc(&auxdev->dev,
177 struct drm_aux_hpd_bridge_data, bridge,
178 &drm_aux_hpd_bridge_funcs);
179 if (IS_ERR(data))
180 return PTR_ERR(data);
181
182 data->dev = &auxdev->dev;
183 data->bridge.of_node = dev_get_platdata(data->dev);
184 data->bridge.ops = DRM_BRIDGE_OP_HPD;
185 data->bridge.type = id->driver_data;
186
187 /* passthrough data, allow everything */
188 data->bridge.interlace_allowed = true;
189 data->bridge.ycbcr_420_allowed = true;
190
191 auxiliary_set_drvdata(auxdev, data);
192
193 return devm_drm_bridge_add(data->dev, &data->bridge);
194 }
195
196 static const struct auxiliary_device_id drm_aux_hpd_bridge_table[] = {
197 { .name = KBUILD_MODNAME ".dp_hpd_bridge", .driver_data = DRM_MODE_CONNECTOR_DisplayPort, },
198 {},
199 };
200 MODULE_DEVICE_TABLE(auxiliary, drm_aux_hpd_bridge_table);
201
202 static struct auxiliary_driver drm_aux_hpd_bridge_drv = {
203 .name = "aux_hpd_bridge",
204 .id_table = drm_aux_hpd_bridge_table,
205 .probe = drm_aux_hpd_bridge_probe,
206 };
207 module_auxiliary_driver(drm_aux_hpd_bridge_drv);
208
209 MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
210 MODULE_DESCRIPTION("DRM HPD bridge");
211 MODULE_LICENSE("GPL");
212