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