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

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2023 Linaro Ltd.
   4  *
   5  * Author: Dmitry Baryshkov <[email protected]>
   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
  14 static DEFINE_IDA(drm_aux_hpd_bridge_ida);
  15
  16 struct drm_aux_hpd_bridge_data {
  17         struct drm_bridge bridge;
  18         struct device *dev;
  19 };
  20
  21 static void drm_aux_hpd_bridge_release(struct device *dev)
  22 {
  23         struct auxiliary_device *adev = to_auxiliary_dev(dev);
  24
  25         ida_free(&drm_aux_hpd_bridge_ida, adev->id);
  26
  27         of_node_put(adev->dev.platform_data);
  28
  29         kfree(adev);
  30 }
  31
  32 static void drm_aux_hpd_bridge_unregister_adev(void *_adev)
  33 {
  34         struct auxiliary_device *adev = _adev;
  35
  36         auxiliary_device_delete(adev);
  37         auxiliary_device_uninit(adev);
  38 }
  39
  40 /**
  41  * drm_dp_hpd_bridge_register - Create a simple HPD DisplayPort bridge
  42  * @parent: device instance providing this bridge
  43  * @np: device node pointer corresponding to this bridge instance
  44  *
  45  * Creates a simple DRM bridge with the type set to
  46  * DRM_MODE_CONNECTOR_DisplayPort, which terminates the bridge chain and is
  47  * able to send the HPD events.
  48  *
  49  * Return: device instance that will handle created bridge or an error code
  50  * encoded into the pointer.
  51  */
  52 struct device *drm_dp_hpd_bridge_register(struct device *parent,
  53                                           struct device_node *np)
  54 {
  55         struct auxiliary_device *adev;
  56         int ret;
  57
  58         adev = kzalloc(sizeof(*adev), GFP_KERNEL);
  59         if (!adev)
  60                 return ERR_PTR(-ENOMEM);
  61
  62         ret = ida_alloc(&drm_aux_hpd_bridge_ida, GFP_KERNEL);
  63         if (ret < 0) {
  64                 kfree(adev);
  65                 return ERR_PTR(ret);
  66         }
  67
  68         adev->id = ret;
  69         adev->name = "dp_hpd_bridge";
  70         adev->dev.parent = parent;
  71         adev->dev.of_node = of_node_get(parent->of_node);
  72         adev->dev.release = drm_aux_hpd_bridge_release;
  73         adev->dev.platform_data = of_node_get(np);
  74
  75         ret = auxiliary_device_init(adev);
  76         if (ret) {
  77                 ida_free(&drm_aux_hpd_bridge_ida, adev->id);
  78                 kfree(adev);
  79                 return ERR_PTR(ret);
  80         }
  81
  82         ret = auxiliary_device_add(adev);
  83         if (ret) {
  84                 auxiliary_device_uninit(adev);
  85                 return ERR_PTR(ret);
  86         }
  87
  88         ret = devm_add_action_or_reset(parent, drm_aux_hpd_bridge_unregister_adev, adev);
  89         if (ret)
  90                 return ERR_PTR(ret);
  91
  92         return &adev->dev;
  93 }
  94 EXPORT_SYMBOL_GPL(drm_dp_hpd_bridge_register);
  95
  96 /**
  97  * drm_aux_hpd_bridge_notify - notify hot plug detection events
  98  * @dev: device created for the HPD bridge
  99  * @status: output connection status
 100  *
 101  * A wrapper around drm_bridge_hpd_notify() that is used to report hot plug
 102  * detection events for bridges created via drm_dp_hpd_bridge_register().
 103  *
 104  * This function shall be called in a context that can sleep.
 105  */
 106 void drm_aux_hpd_bridge_notify(struct device *dev, enum drm_connector_status status)
 107 {
 108         struct auxiliary_device *adev = to_auxiliary_dev(dev);
 109         struct drm_aux_hpd_bridge_data *data = auxiliary_get_drvdata(adev);
 110
 111         if (!data)
 112                 return;
 113
 114         drm_bridge_hpd_notify(&data->bridge, status);
 115 }
 116 EXPORT_SYMBOL_GPL(drm_aux_hpd_bridge_notify);
 117
 118 static int drm_aux_hpd_bridge_attach(struct drm_bridge *bridge,
 119                                      enum drm_bridge_attach_flags flags)
 120 {
 121         return flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR ? 0 : -EINVAL;
 122 }
 123
 124 static const struct drm_bridge_funcs drm_aux_hpd_bridge_funcs = {
 125         .attach = drm_aux_hpd_bridge_attach,
 126 };
 127
 128 static int drm_aux_hpd_bridge_probe(struct auxiliary_device *auxdev,
 129                                     const struct auxiliary_device_id *id)
 130 {
 131         struct drm_aux_hpd_bridge_data *data;
 132
 133         data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
 134         if (!data)
 135                 return -ENOMEM;
 136
 137         data->dev = &auxdev->dev;
 138         data->bridge.funcs = &drm_aux_hpd_bridge_funcs;
 139         data->bridge.of_node = dev_get_platdata(data->dev);
 140         data->bridge.ops = DRM_BRIDGE_OP_HPD;
 141         data->bridge.type = id->driver_data;
 142
 143         auxiliary_set_drvdata(auxdev, data);
 144
 145         return devm_drm_bridge_add(data->dev, &data->bridge);
 146 }
 147
 148 static const struct auxiliary_device_id drm_aux_hpd_bridge_table[] = {
 149         { .name = KBUILD_MODNAME ".dp_hpd_bridge", .driver_data = DRM_MODE_CONNECTOR_DisplayPort, },
 150         {},
 151 };
 152 MODULE_DEVICE_TABLE(auxiliary, drm_aux_hpd_bridge_table);
 153
 154 static struct auxiliary_driver drm_aux_hpd_bridge_drv = {
 155         .name = "aux_hpd_bridge",
 156         .id_table = drm_aux_hpd_bridge_table,
 157         .probe = drm_aux_hpd_bridge_probe,
 158 };
 159 module_auxiliary_driver(drm_aux_hpd_bridge_drv);
 160
 161 MODULE_AUTHOR("Dmitry Baryshkov <[email protected]>");
 162 MODULE_DESCRIPTION("DRM HPD bridge");
 163 MODULE_LICENSE("GPL");