drivers/gpu/drm/bridge/aux-hpd-bridge.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2023 Linaro Ltd.
 *
 * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
 */
#include <linux/auxiliary_bus.h>
#include <linux/module.h>
#include <linux/of.h>

#include <drm/drm_bridge.h>
#include <drm/bridge/aux-bridge.h>

static DEFINE_IDA(drm_aux_hpd_bridge_ida);

struct drm_aux_hpd_bridge_data {
	struct drm_bridge bridge;
	struct device *dev;
};

static void drm_aux_hpd_bridge_release(struct device *dev)
{
	struct auxiliary_device *adev = to_auxiliary_dev(dev);

	ida_free(&drm_aux_hpd_bridge_ida, adev->id);

	of_node_put(adev->dev.platform_data);

	kfree(adev);
}

static void drm_aux_hpd_bridge_unregister_adev(void *_adev)
{
	struct auxiliary_device *adev = _adev;

	auxiliary_device_delete(adev);
	auxiliary_device_uninit(adev);
}

/**
 * drm_dp_hpd_bridge_register - Create a simple HPD DisplayPort bridge
 * @parent: device instance providing this bridge
 * @np: device node pointer corresponding to this bridge instance
 *
 * Creates a simple DRM bridge with the type set to
 * DRM_MODE_CONNECTOR_DisplayPort, which terminates the bridge chain and is
 * able to send the HPD events.
 *
 * Return: device instance that will handle created bridge or an error code
 * encoded into the pointer.
 */
struct device *drm_dp_hpd_bridge_register(struct device *parent,
					  struct device_node *np)
{
	struct auxiliary_device *adev;
	int ret;

	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
	if (!adev)
		return ERR_PTR(-ENOMEM);

	ret = ida_alloc(&drm_aux_hpd_bridge_ida, GFP_KERNEL);
	if (ret < 0) {
		kfree(adev);
		return ERR_PTR(ret);
	}

	adev->id = ret;
	adev->name = "dp_hpd_bridge";
	adev->dev.parent = parent;
	adev->dev.of_node = of_node_get(parent->of_node);
	adev->dev.release = drm_aux_hpd_bridge_release;
	adev->dev.platform_data = of_node_get(np);

	ret = auxiliary_device_init(adev);
	if (ret) {
		ida_free(&drm_aux_hpd_bridge_ida, adev->id);
		kfree(adev);
		return ERR_PTR(ret);
	}

	ret = auxiliary_device_add(adev);
	if (ret) {
		auxiliary_device_uninit(adev);
		return ERR_PTR(ret);
	}

	ret = devm_add_action_or_reset(parent, drm_aux_hpd_bridge_unregister_adev, adev);
	if (ret)
		return ERR_PTR(ret);

	return &adev->dev;
}
EXPORT_SYMBOL_GPL(drm_dp_hpd_bridge_register);

/**
 * drm_aux_hpd_bridge_notify - notify hot plug detection events
 * @dev: device created for the HPD bridge
 * @status: output connection status
 *
 * A wrapper around drm_bridge_hpd_notify() that is used to report hot plug
 * detection events for bridges created via drm_dp_hpd_bridge_register().
 *
 * This function shall be called in a context that can sleep.
 */
void drm_aux_hpd_bridge_notify(struct device *dev, enum drm_connector_status status)
{
	struct auxiliary_device *adev = to_auxiliary_dev(dev);
	struct drm_aux_hpd_bridge_data *data = auxiliary_get_drvdata(adev);

	if (!data)
		return;

	drm_bridge_hpd_notify(&data->bridge, status);
}
EXPORT_SYMBOL_GPL(drm_aux_hpd_bridge_notify);

static int drm_aux_hpd_bridge_attach(struct drm_bridge *bridge,
				     enum drm_bridge_attach_flags flags)
{
	return flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR ? 0 : -EINVAL;
}

static const struct drm_bridge_funcs drm_aux_hpd_bridge_funcs = {
	.attach	= drm_aux_hpd_bridge_attach,
};

static int drm_aux_hpd_bridge_probe(struct auxiliary_device *auxdev,
				    const struct auxiliary_device_id *id)
{
	struct drm_aux_hpd_bridge_data *data;

	data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->dev = &auxdev->dev;
	data->bridge.funcs = &drm_aux_hpd_bridge_funcs;
	data->bridge.of_node = dev_get_platdata(data->dev);
	data->bridge.ops = DRM_BRIDGE_OP_HPD;
	data->bridge.type = id->driver_data;

	auxiliary_set_drvdata(auxdev, data);

	return devm_drm_bridge_add(data->dev, &data->bridge);
}

static const struct auxiliary_device_id drm_aux_hpd_bridge_table[] = {
	{ .name = KBUILD_MODNAME ".dp_hpd_bridge", .driver_data = DRM_MODE_CONNECTOR_DisplayPort, },
	{},
};
MODULE_DEVICE_TABLE(auxiliary, drm_aux_hpd_bridge_table);

static struct auxiliary_driver drm_aux_hpd_bridge_drv = {
	.name = "aux_hpd_bridge",
	.id_table = drm_aux_hpd_bridge_table,
	.probe = drm_aux_hpd_bridge_probe,
};
module_auxiliary_driver(drm_aux_hpd_bridge_drv);

MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
MODULE_DESCRIPTION("DRM HPD bridge");
MODULE_LICENSE("GPL");