aux-hpd-bridge.c

  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
 15static DEFINE_IDA(drm_aux_hpd_bridge_ida);
 16
 17struct drm_aux_hpd_bridge_data {
 18	struct drm_bridge bridge;
 19	struct device *dev;
 20};
 21
 22static 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
 34static 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 */
 50struct 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}
 88EXPORT_SYMBOL_GPL(devm_drm_dp_hpd_bridge_alloc);
 89
 90static 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 */
102int 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}
112EXPORT_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 */
121struct 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}
136EXPORT_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 */
148void 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}
158EXPORT_SYMBOL_GPL(drm_aux_hpd_bridge_notify);
159
160static 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
167static const struct drm_bridge_funcs drm_aux_hpd_bridge_funcs = {
168	.attach	= drm_aux_hpd_bridge_attach,
169};
170
171static 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
196static 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};
200MODULE_DEVICE_TABLE(auxiliary, drm_aux_hpd_bridge_table);
201
202static 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};
207module_auxiliary_driver(drm_aux_hpd_bridge_drv);
208
209MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
210MODULE_DESCRIPTION("DRM HPD bridge");
211MODULE_LICENSE("GPL");