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