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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 14static DEFINE_IDA(drm_aux_bridge_ida);15 16static void drm_aux_bridge_release(struct device *dev)17{18 struct auxiliary_device *adev = to_auxiliary_dev(dev);19 20 ida_free(&drm_aux_bridge_ida, adev->id);21 22 kfree(adev);23}24 25static void drm_aux_bridge_unregister_adev(void *_adev)26{27 struct auxiliary_device *adev = _adev;28 29 auxiliary_device_delete(adev);30 auxiliary_device_uninit(adev);31}32 33/**34 * drm_aux_bridge_register - Create a simple bridge device to link the chain35 * @parent: device instance providing this bridge36 *37 * Creates a simple DRM bridge that doesn't implement any drm_bridge38 * operations. Such bridges merely fill a place in the bridge chain linking39 * surrounding DRM bridges.40 *41 * Return: zero on success, negative error code on failure42 */43int drm_aux_bridge_register(struct device *parent)44{45 struct auxiliary_device *adev;46 int ret;47 48 adev = kzalloc(sizeof(*adev), GFP_KERNEL);49 if (!adev)50 return -ENOMEM;51 52 ret = ida_alloc(&drm_aux_bridge_ida, GFP_KERNEL);53 if (ret < 0) {54 kfree(adev);55 return ret;56 }57 58 adev->id = ret;59 adev->name = "aux_bridge";60 adev->dev.parent = parent;61 adev->dev.release = drm_aux_bridge_release;62 63 device_set_of_node_from_dev(&adev->dev, parent);64 65 ret = auxiliary_device_init(adev);66 if (ret) {67 ida_free(&drm_aux_bridge_ida, adev->id);68 kfree(adev);69 return ret;70 }71 72 ret = auxiliary_device_add(adev);73 if (ret) {74 auxiliary_device_uninit(adev);75 return ret;76 }77 78 return devm_add_action_or_reset(parent, drm_aux_bridge_unregister_adev, adev);79}80EXPORT_SYMBOL_GPL(drm_aux_bridge_register);81 82struct drm_aux_bridge_data {83 struct drm_bridge bridge;84 struct drm_bridge *next_bridge;85 struct device *dev;86};87 88static int drm_aux_bridge_attach(struct drm_bridge *bridge,89 enum drm_bridge_attach_flags flags)90{91 struct drm_aux_bridge_data *data;92 93 if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))94 return -EINVAL;95 96 data = container_of(bridge, struct drm_aux_bridge_data, bridge);97 98 return drm_bridge_attach(bridge->encoder, data->next_bridge, bridge,99 DRM_BRIDGE_ATTACH_NO_CONNECTOR);100}101 102static const struct drm_bridge_funcs drm_aux_bridge_funcs = {103 .attach = drm_aux_bridge_attach,104};105 106static int drm_aux_bridge_probe(struct auxiliary_device *auxdev,107 const struct auxiliary_device_id *id)108{109 struct drm_aux_bridge_data *data;110 111 data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);112 if (!data)113 return -ENOMEM;114 115 data->dev = &auxdev->dev;116 data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);117 if (IS_ERR(data->next_bridge))118 return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),119 "failed to acquire drm_bridge\n");120 121 data->bridge.funcs = &drm_aux_bridge_funcs;122 data->bridge.of_node = data->dev->of_node;123 124 return devm_drm_bridge_add(data->dev, &data->bridge);125}126 127static const struct auxiliary_device_id drm_aux_bridge_table[] = {128 { .name = KBUILD_MODNAME ".aux_bridge" },129 {},130};131MODULE_DEVICE_TABLE(auxiliary, drm_aux_bridge_table);132 133static struct auxiliary_driver drm_aux_bridge_drv = {134 .name = "aux_bridge",135 .id_table = drm_aux_bridge_table,136 .probe = drm_aux_bridge_probe,137};138module_auxiliary_driver(drm_aux_bridge_drv);139 140MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");141MODULE_DESCRIPTION("DRM transparent bridge");142MODULE_LICENSE("GPL");143