drivers/gpu/drm/drm_panel.c

   1 /*
   2  * Copyright (C) 2013, NVIDIA Corporation.  All rights reserved.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sub license,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the
  12  * next paragraph) shall be included in all copies or substantial portions
  13  * of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #include <linux/err.h>
  25 #include <linux/module.h>
  26
  27 #include <drm/drm_crtc.h>
  28 #include <drm/drm_panel.h>
  29
  30 static DEFINE_MUTEX(panel_lock);
  31 static LIST_HEAD(panel_list);
  32
  33 /**
  34  * DOC: drm panel
  35  *
  36  * The DRM panel helpers allow drivers to register panel objects with a
  37  * central registry and provide functions to retrieve those panels in display
  38  * drivers.
  39  */
  40
  41 /**
  42  * drm_panel_init - initialize a panel
  43  * @panel: DRM panel
  44  *
  45  * Sets up internal fields of the panel so that it can subsequently be added
  46  * to the registry.
  47  */
  48 void drm_panel_init(struct drm_panel *panel)
  49 {
  50         INIT_LIST_HEAD(&panel->list);
  51 }
  52 EXPORT_SYMBOL(drm_panel_init);
  53
  54 /**
  55  * drm_panel_add - add a panel to the global registry
  56  * @panel: panel to add
  57  *
  58  * Add a panel to the global registry so that it can be looked up by display
  59  * drivers.
  60  *
  61  * Return: 0 on success or a negative error code on failure.
  62  */
  63 int drm_panel_add(struct drm_panel *panel)
  64 {
  65         mutex_lock(&panel_lock);
  66         list_add_tail(&panel->list, &panel_list);
  67         mutex_unlock(&panel_lock);
  68
  69         return 0;
  70 }
  71 EXPORT_SYMBOL(drm_panel_add);
  72
  73 /**
  74  * drm_panel_remove - remove a panel from the global registry
  75  * @panel: DRM panel
  76  *
  77  * Removes a panel from the global registry.
  78  */
  79 void drm_panel_remove(struct drm_panel *panel)
  80 {
  81         mutex_lock(&panel_lock);
  82         list_del_init(&panel->list);
  83         mutex_unlock(&panel_lock);
  84 }
  85 EXPORT_SYMBOL(drm_panel_remove);
  86
  87 /**
  88  * drm_panel_attach - attach a panel to a connector
  89  * @panel: DRM panel
  90  * @connector: DRM connector
  91  *
  92  * After obtaining a pointer to a DRM panel a display driver calls this
  93  * function to attach a panel to a connector.
  94  *
  95  * An error is returned if the panel is already attached to another connector.
  96  *
  97  * When unloading, the driver should detach from the panel by calling
  98  * drm_panel_detach().
  99  *
 100  * Return: 0 on success or a negative error code on failure.
 101  */
 102 int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector)
 103 {
 104         if (panel->connector)
 105                 return -EBUSY;
 106
 107         panel->connector = connector;
 108         panel->drm = connector->dev;
 109
 110         return 0;
 111 }
 112 EXPORT_SYMBOL(drm_panel_attach);
 113
 114 /**
 115  * drm_panel_detach - detach a panel from a connector
 116  * @panel: DRM panel
 117  *
 118  * Detaches a panel from the connector it is attached to. If a panel is not
 119  * attached to any connector this is effectively a no-op.
 120  *
 121  * This function should not be called by the panel device itself. It
 122  * is only for the drm device that called drm_panel_attach().
 123  *
 124  * Return: 0 on success or a negative error code on failure.
 125  */
 126 int drm_panel_detach(struct drm_panel *panel)
 127 {
 128         panel->connector = NULL;
 129         panel->drm = NULL;
 130
 131         return 0;
 132 }
 133 EXPORT_SYMBOL(drm_panel_detach);
 134
 135 #ifdef CONFIG_OF
 136 /**
 137  * of_drm_find_panel - look up a panel using a device tree node
 138  * @np: device tree node of the panel
 139  *
 140  * Searches the set of registered panels for one that matches the given device
 141  * tree node. If a matching panel is found, return a pointer to it.
 142  *
 143  * Return: A pointer to the panel registered for the specified device tree
 144  * node or an ERR_PTR() if no panel matching the device tree node can be found.
 145  * Possible error codes returned by this function:
 146  * - EPROBE_DEFER: the panel device has not been probed yet, and the caller
 147  *   should retry later
 148  * - ENODEV: the device is not available (status != "okay" or "ok")
 149  */
 150 struct drm_panel *of_drm_find_panel(const struct device_node *np)
 151 {
 152         struct drm_panel *panel;
 153
 154         if (!of_device_is_available(np))
 155                 return ERR_PTR(-ENODEV);
 156
 157         mutex_lock(&panel_lock);
 158
 159         list_for_each_entry(panel, &panel_list, list) {
 160                 if (panel->dev->of_node == np) {
 161                         mutex_unlock(&panel_lock);
 162                         return panel;
 163                 }
 164         }
 165
 166         mutex_unlock(&panel_lock);
 167         return ERR_PTR(-EPROBE_DEFER);
 168 }
 169 EXPORT_SYMBOL(of_drm_find_panel);
 170 #endif
 171
 172 MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
 173 MODULE_DESCRIPTION("DRM panel infrastructure");
 174 MODULE_LICENSE("GPL and additional rights");