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_device.h> 28 #include <drm/drm_crtc.h> 29 #include <drm/drm_panel.h> 30 31 static DEFINE_MUTEX(panel_lock); 32 static LIST_HEAD(panel_list); 33 34 /** 35 * DOC: drm panel 36 * 37 * The DRM panel helpers allow drivers to register panel objects with a 38 * central registry and provide functions to retrieve those panels in display 39 * drivers. 40 */ 41 42 /** 43 * drm_panel_init - initialize a panel 44 * @panel: DRM panel 45 * 46 * Sets up internal fields of the panel so that it can subsequently be added 47 * to the registry. 48 */ 49 void drm_panel_init(struct drm_panel *panel) 50 { 51 INIT_LIST_HEAD(&panel->list); 52 } 53 EXPORT_SYMBOL(drm_panel_init); 54 55 /** 56 * drm_panel_add - add a panel to the global registry 57 * @panel: panel to add 58 * 59 * Add a panel to the global registry so that it can be looked up by display 60 * drivers. 61 * 62 * Return: 0 on success or a negative error code on failure. 63 */ 64 int drm_panel_add(struct drm_panel *panel) 65 { 66 mutex_lock(&panel_lock); 67 list_add_tail(&panel->list, &panel_list); 68 mutex_unlock(&panel_lock); 69 70 return 0; 71 } 72 EXPORT_SYMBOL(drm_panel_add); 73 74 /** 75 * drm_panel_remove - remove a panel from the global registry 76 * @panel: DRM panel 77 * 78 * Removes a panel from the global registry. 79 */ 80 void drm_panel_remove(struct drm_panel *panel) 81 { 82 mutex_lock(&panel_lock); 83 list_del_init(&panel->list); 84 mutex_unlock(&panel_lock); 85 } 86 EXPORT_SYMBOL(drm_panel_remove); 87 88 /** 89 * drm_panel_attach - attach a panel to a connector 90 * @panel: DRM panel 91 * @connector: DRM connector 92 * 93 * After obtaining a pointer to a DRM panel a display driver calls this 94 * function to attach a panel to a connector. 95 * 96 * An error is returned if the panel is already attached to another connector. 97 * 98 * When unloading, the driver should detach from the panel by calling 99 * drm_panel_detach(). 100 * 101 * Return: 0 on success or a negative error code on failure. 102 */ 103 int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector) 104 { 105 if (panel->connector) 106 return -EBUSY; 107 108 panel->link = device_link_add(connector->dev->dev, panel->dev, 0); 109 if (!panel->link) { 110 dev_err(panel->dev, "failed to link panel to %s\n", 111 dev_name(connector->dev->dev)); 112 return -EINVAL; 113 } 114 115 panel->connector = connector; 116 panel->drm = connector->dev; 117 118 return 0; 119 } 120 EXPORT_SYMBOL(drm_panel_attach); 121 122 /** 123 * drm_panel_detach - detach a panel from a connector 124 * @panel: DRM panel 125 * 126 * Detaches a panel from the connector it is attached to. If a panel is not 127 * attached to any connector this is effectively a no-op. 128 * 129 * This function should not be called by the panel device itself. It 130 * is only for the drm device that called drm_panel_attach(). 131 * 132 * Return: 0 on success or a negative error code on failure. 133 */ 134 int drm_panel_detach(struct drm_panel *panel) 135 { 136 device_link_del(panel->link); 137 138 panel->connector = NULL; 139 panel->drm = NULL; 140 141 return 0; 142 } 143 EXPORT_SYMBOL(drm_panel_detach); 144 145 #ifdef CONFIG_OF 146 /** 147 * of_drm_find_panel - look up a panel using a device tree node 148 * @np: device tree node of the panel 149 * 150 * Searches the set of registered panels for one that matches the given device 151 * tree node. If a matching panel is found, return a pointer to it. 152 * 153 * Return: A pointer to the panel registered for the specified device tree 154 * node or an ERR_PTR() if no panel matching the device tree node can be found. 155 * Possible error codes returned by this function: 156 * - EPROBE_DEFER: the panel device has not been probed yet, and the caller 157 * should retry later 158 * - ENODEV: the device is not available (status != "okay" or "ok") 159 */ 160 struct drm_panel *of_drm_find_panel(const struct device_node *np) 161 { 162 struct drm_panel *panel; 163 164 if (!of_device_is_available(np)) 165 return ERR_PTR(-ENODEV); 166 167 mutex_lock(&panel_lock); 168 169 list_for_each_entry(panel, &panel_list, list) { 170 if (panel->dev->of_node == np) { 171 mutex_unlock(&panel_lock); 172 return panel; 173 } 174 } 175 176 mutex_unlock(&panel_lock); 177 return ERR_PTR(-EPROBE_DEFER); 178 } 179 EXPORT_SYMBOL(of_drm_find_panel); 180 #endif 181 182 MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>"); 183 MODULE_DESCRIPTION("DRM panel infrastructure"); 184 MODULE_LICENSE("GPL and additional rights"); 185