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 15 static DEFINE_IDA(drm_aux_bridge_ida); 16 17 static void drm_aux_bridge_release(struct device *dev) 18 { 19 struct auxiliary_device *adev = to_auxiliary_dev(dev); 20 21 of_node_put(dev->of_node); 22 ida_free(&drm_aux_bridge_ida, adev->id); 23 24 kfree(adev); 25 } 26 27 static void drm_aux_bridge_unregister_adev(void *_adev) 28 { 29 struct auxiliary_device *adev = _adev; 30 31 auxiliary_device_delete(adev); 32 auxiliary_device_uninit(adev); 33 } 34 35 /** 36 * drm_aux_bridge_register - Create a simple bridge device to link the chain 37 * @parent: device instance providing this bridge 38 * 39 * Creates a simple DRM bridge that doesn't implement any drm_bridge 40 * operations. Such bridges merely fill a place in the bridge chain linking 41 * surrounding DRM bridges. 42 * 43 * Return: zero on success, negative error code on failure 44 */ 45 int drm_aux_bridge_register(struct device *parent) 46 { 47 struct auxiliary_device *adev; 48 int ret; 49 50 adev = kzalloc(sizeof(*adev), GFP_KERNEL); 51 if (!adev) 52 return -ENOMEM; 53 54 ret = ida_alloc(&drm_aux_bridge_ida, GFP_KERNEL); 55 if (ret < 0) { 56 kfree(adev); 57 return ret; 58 } 59 60 adev->id = ret; 61 adev->name = "aux_bridge"; 62 adev->dev.parent = parent; 63 adev->dev.release = drm_aux_bridge_release; 64 65 device_set_of_node_from_dev(&adev->dev, parent); 66 67 ret = auxiliary_device_init(adev); 68 if (ret) { 69 of_node_put(adev->dev.of_node); 70 ida_free(&drm_aux_bridge_ida, adev->id); 71 kfree(adev); 72 return ret; 73 } 74 75 ret = auxiliary_device_add(adev); 76 if (ret) { 77 auxiliary_device_uninit(adev); 78 return ret; 79 } 80 81 return devm_add_action_or_reset(parent, drm_aux_bridge_unregister_adev, adev); 82 } 83 EXPORT_SYMBOL_GPL(drm_aux_bridge_register); 84 85 struct drm_aux_bridge_data { 86 struct drm_bridge bridge; 87 struct drm_bridge *next_bridge; 88 struct device *dev; 89 }; 90 91 static int drm_aux_bridge_attach(struct drm_bridge *bridge, 92 struct drm_encoder *encoder, 93 enum drm_bridge_attach_flags flags) 94 { 95 struct drm_aux_bridge_data *data; 96 97 if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) 98 return -EINVAL; 99 100 data = container_of(bridge, struct drm_aux_bridge_data, bridge); 101 102 return drm_bridge_attach(encoder, data->next_bridge, bridge, 103 DRM_BRIDGE_ATTACH_NO_CONNECTOR); 104 } 105 106 static const struct drm_bridge_funcs drm_aux_bridge_funcs = { 107 .attach = drm_aux_bridge_attach, 108 }; 109 110 static int drm_aux_bridge_probe(struct auxiliary_device *auxdev, 111 const struct auxiliary_device_id *id) 112 { 113 struct drm_aux_bridge_data *data; 114 115 data = devm_drm_bridge_alloc(&auxdev->dev, struct drm_aux_bridge_data, 116 bridge, &drm_aux_bridge_funcs); 117 if (IS_ERR(data)) 118 return PTR_ERR(data); 119 120 data->dev = &auxdev->dev; 121 data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0); 122 if (IS_ERR(data->next_bridge)) 123 return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge), 124 "failed to acquire drm_bridge\n"); 125 126 data->bridge.of_node = data->dev->of_node; 127 128 /* passthrough data, allow everything */ 129 data->bridge.interlace_allowed = true; 130 data->bridge.ycbcr_420_allowed = true; 131 132 return devm_drm_bridge_add(data->dev, &data->bridge); 133 } 134 135 static const struct auxiliary_device_id drm_aux_bridge_table[] = { 136 { .name = KBUILD_MODNAME ".aux_bridge" }, 137 {}, 138 }; 139 MODULE_DEVICE_TABLE(auxiliary, drm_aux_bridge_table); 140 141 static struct auxiliary_driver drm_aux_bridge_drv = { 142 .name = "aux_bridge", 143 .id_table = drm_aux_bridge_table, 144 .probe = drm_aux_bridge_probe, 145 }; 146 module_auxiliary_driver(drm_aux_bridge_drv); 147 148 MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>"); 149 MODULE_DESCRIPTION("DRM transparent bridge"); 150 MODULE_LICENSE("GPL"); 151