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// 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_bridge_ida);
static void drm_aux_bridge_release(struct device *dev)
{
struct auxiliary_device *adev = to_auxiliary_dev(dev);
ida_free(&drm_aux_bridge_ida, adev->id);
kfree(adev);
}
static void drm_aux_bridge_unregister_adev(void *_adev)
{
struct auxiliary_device *adev = _adev;
auxiliary_device_delete(adev);
auxiliary_device_uninit(adev);
}
/**
* drm_aux_bridge_register - Create a simple bridge device to link the chain
* @parent: device instance providing this bridge
*
* Creates a simple DRM bridge that doesn't implement any drm_bridge
* operations. Such bridges merely fill a place in the bridge chain linking
* surrounding DRM bridges.
*
* Return: zero on success, negative error code on failure
*/
int drm_aux_bridge_register(struct device *parent)
{
struct auxiliary_device *adev;
int ret;
adev = kzalloc(sizeof(*adev), GFP_KERNEL);
if (!adev)
return -ENOMEM;
ret = ida_alloc(&drm_aux_bridge_ida, GFP_KERNEL);
if (ret < 0) {
kfree(adev);
return ret;
}
adev->id = ret;
adev->name = "aux_bridge";
adev->dev.parent = parent;
adev->dev.release = drm_aux_bridge_release;
device_set_of_node_from_dev(&adev->dev, parent);
ret = auxiliary_device_init(adev);
if (ret) {
ida_free(&drm_aux_bridge_ida, adev->id);
kfree(adev);
return ret;
}
ret = auxiliary_device_add(adev);
if (ret) {
auxiliary_device_uninit(adev);
return ret;
}
return devm_add_action_or_reset(parent, drm_aux_bridge_unregister_adev, adev);
}
EXPORT_SYMBOL_GPL(drm_aux_bridge_register);
struct drm_aux_bridge_data {
struct drm_bridge bridge;
struct drm_bridge *next_bridge;
struct device *dev;
};
static int drm_aux_bridge_attach(struct drm_bridge *bridge,
struct drm_encoder *encoder,
enum drm_bridge_attach_flags flags)
{
struct drm_aux_bridge_data *data;
if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
return -EINVAL;
data = container_of(bridge, struct drm_aux_bridge_data, bridge);
return drm_bridge_attach(encoder, data->next_bridge, bridge,
DRM_BRIDGE_ATTACH_NO_CONNECTOR);
}
static const struct drm_bridge_funcs drm_aux_bridge_funcs = {
.attach = drm_aux_bridge_attach,
};
static int drm_aux_bridge_probe(struct auxiliary_device *auxdev,
const struct auxiliary_device_id *id)
{
struct drm_aux_bridge_data *data;
data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->dev = &auxdev->dev;
data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);
if (IS_ERR(data->next_bridge))
return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),
"failed to acquire drm_bridge\n");
data->bridge.funcs = &drm_aux_bridge_funcs;
data->bridge.of_node = data->dev->of_node;
/* passthrough data, allow everything */
data->bridge.interlace_allowed = true;
data->bridge.ycbcr_420_allowed = true;
return devm_drm_bridge_add(data->dev, &data->bridge);
}
static const struct auxiliary_device_id drm_aux_bridge_table[] = {
{ .name = KBUILD_MODNAME ".aux_bridge" },
{},
};
MODULE_DEVICE_TABLE(auxiliary, drm_aux_bridge_table);
static struct auxiliary_driver drm_aux_bridge_drv = {
.name = "aux_bridge",
.id_table = drm_aux_bridge_table,
.probe = drm_aux_bridge_probe,
};
module_auxiliary_driver(drm_aux_bridge_drv);
MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
MODULE_DESCRIPTION("DRM transparent bridge");
MODULE_LICENSE("GPL");
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