1 /* 2 * Copyright (c) 2014 Samsung Electronics Co., Ltd 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 29 #include "drm/drmP.h" 30 31 /** 32 * DOC: overview 33 * 34 * struct &drm_bridge represents a device that hangs on to an encoder. These are 35 * handy when a regular &drm_encoder entity isn't enough to represent the entire 36 * encoder chain. 37 * 38 * A bridge is always attached to a single &drm_encoder at a time, but can be 39 * either connected to it directly, or through an intermediate bridge: 40 * 41 * encoder ---> bridge B ---> bridge A 42 * 43 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to 44 * bridge A. 45 * 46 * The driver using the bridge is responsible to make the associations between 47 * the encoder and bridges. Once these links are made, the bridges will 48 * participate along with encoder functions to perform mode_set/enable/disable 49 * through the ops provided in &drm_bridge_funcs. 50 * 51 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes, 52 * CRTCs, encoders or connectors and hence are not visible to userspace. They 53 * just provide additional hooks to get the desired output at the end of the 54 * encoder chain. 55 * 56 * Bridges can also be chained up using the next pointer in struct &drm_bridge. 57 * 58 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges. 59 */ 60 61 static DEFINE_MUTEX(bridge_lock); 62 static LIST_HEAD(bridge_list); 63 64 /** 65 * drm_bridge_add - add the given bridge to the global bridge list 66 * 67 * @bridge: bridge control structure 68 * 69 * RETURNS: 70 * Unconditionally returns Zero. 71 */ 72 int drm_bridge_add(struct drm_bridge *bridge) 73 { 74 mutex_lock(&bridge_lock); 75 list_add_tail(&bridge->list, &bridge_list); 76 mutex_unlock(&bridge_lock); 77 78 return 0; 79 } 80 EXPORT_SYMBOL(drm_bridge_add); 81 82 /** 83 * drm_bridge_remove - remove the given bridge from the global bridge list 84 * 85 * @bridge: bridge control structure 86 */ 87 void drm_bridge_remove(struct drm_bridge *bridge) 88 { 89 mutex_lock(&bridge_lock); 90 list_del_init(&bridge->list); 91 mutex_unlock(&bridge_lock); 92 } 93 EXPORT_SYMBOL(drm_bridge_remove); 94 95 /** 96 * drm_bridge_attach - associate given bridge to our DRM device 97 * 98 * @dev: DRM device 99 * @bridge: bridge control structure 100 * 101 * called by a kms driver to link one of our encoder/bridge to the given 102 * bridge. 103 * 104 * Note that setting up links between the bridge and our encoder/bridge 105 * objects needs to be handled by the kms driver itself 106 * 107 * RETURNS: 108 * Zero on success, error code on failure 109 */ 110 int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge) 111 { 112 if (!dev || !bridge) 113 return -EINVAL; 114 115 if (bridge->dev) 116 return -EBUSY; 117 118 bridge->dev = dev; 119 120 if (bridge->funcs->attach) 121 return bridge->funcs->attach(bridge); 122 123 return 0; 124 } 125 EXPORT_SYMBOL(drm_bridge_attach); 126 127 /** 128 * DOC: bridge callbacks 129 * 130 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM 131 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c 132 * These helpers call a specific &drm_bridge_funcs op for all the bridges 133 * during encoder configuration. 134 * 135 * For detailed specification of the bridge callbacks see &drm_bridge_funcs. 136 */ 137 138 /** 139 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the 140 * encoder chain 141 * @bridge: bridge control structure 142 * @mode: desired mode to be set for the bridge 143 * @adjusted_mode: updated mode that works for this bridge 144 * 145 * Calls ->mode_fixup() &drm_bridge_funcs op for all the bridges in the 146 * encoder chain, starting from the first bridge to the last. 147 * 148 * Note: the bridge passed should be the one closest to the encoder 149 * 150 * RETURNS: 151 * true on success, false on failure 152 */ 153 bool drm_bridge_mode_fixup(struct drm_bridge *bridge, 154 const struct drm_display_mode *mode, 155 struct drm_display_mode *adjusted_mode) 156 { 157 bool ret = true; 158 159 if (!bridge) 160 return true; 161 162 if (bridge->funcs->mode_fixup) 163 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode); 164 165 ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode); 166 167 return ret; 168 } 169 EXPORT_SYMBOL(drm_bridge_mode_fixup); 170 171 /** 172 * drm_bridge_disable - calls ->disable() &drm_bridge_funcs op for all 173 * bridges in the encoder chain. 174 * @bridge: bridge control structure 175 * 176 * Calls ->disable() &drm_bridge_funcs op for all the bridges in the encoder 177 * chain, starting from the last bridge to the first. These are called before 178 * calling the encoder's prepare op. 179 * 180 * Note: the bridge passed should be the one closest to the encoder 181 */ 182 void drm_bridge_disable(struct drm_bridge *bridge) 183 { 184 if (!bridge) 185 return; 186 187 drm_bridge_disable(bridge->next); 188 189 if (bridge->funcs->disable) 190 bridge->funcs->disable(bridge); 191 } 192 EXPORT_SYMBOL(drm_bridge_disable); 193 194 /** 195 * drm_bridge_post_disable - calls ->post_disable() &drm_bridge_funcs op for 196 * all bridges in the encoder chain. 197 * @bridge: bridge control structure 198 * 199 * Calls ->post_disable() &drm_bridge_funcs op for all the bridges in the 200 * encoder chain, starting from the first bridge to the last. These are called 201 * after completing the encoder's prepare op. 202 * 203 * Note: the bridge passed should be the one closest to the encoder 204 */ 205 void drm_bridge_post_disable(struct drm_bridge *bridge) 206 { 207 if (!bridge) 208 return; 209 210 if (bridge->funcs->post_disable) 211 bridge->funcs->post_disable(bridge); 212 213 drm_bridge_post_disable(bridge->next); 214 } 215 EXPORT_SYMBOL(drm_bridge_post_disable); 216 217 /** 218 * drm_bridge_mode_set - set proposed mode for all bridges in the 219 * encoder chain 220 * @bridge: bridge control structure 221 * @mode: desired mode to be set for the bridge 222 * @adjusted_mode: updated mode that works for this bridge 223 * 224 * Calls ->mode_set() &drm_bridge_funcs op for all the bridges in the 225 * encoder chain, starting from the first bridge to the last. 226 * 227 * Note: the bridge passed should be the one closest to the encoder 228 */ 229 void drm_bridge_mode_set(struct drm_bridge *bridge, 230 struct drm_display_mode *mode, 231 struct drm_display_mode *adjusted_mode) 232 { 233 if (!bridge) 234 return; 235 236 if (bridge->funcs->mode_set) 237 bridge->funcs->mode_set(bridge, mode, adjusted_mode); 238 239 drm_bridge_mode_set(bridge->next, mode, adjusted_mode); 240 } 241 EXPORT_SYMBOL(drm_bridge_mode_set); 242 243 /** 244 * drm_bridge_pre_enable - calls ->pre_enable() &drm_bridge_funcs op for all 245 * bridges in the encoder chain. 246 * @bridge: bridge control structure 247 * 248 * Calls ->pre_enable() &drm_bridge_funcs op for all the bridges in the encoder 249 * chain, starting from the last bridge to the first. These are called 250 * before calling the encoder's commit op. 251 * 252 * Note: the bridge passed should be the one closest to the encoder 253 */ 254 void drm_bridge_pre_enable(struct drm_bridge *bridge) 255 { 256 if (!bridge) 257 return; 258 259 drm_bridge_pre_enable(bridge->next); 260 261 if (bridge->funcs->pre_enable) 262 bridge->funcs->pre_enable(bridge); 263 } 264 EXPORT_SYMBOL(drm_bridge_pre_enable); 265 266 /** 267 * drm_bridge_enable - calls ->enable() &drm_bridge_funcs op for all bridges 268 * in the encoder chain. 269 * @bridge: bridge control structure 270 * 271 * Calls ->enable() &drm_bridge_funcs op for all the bridges in the encoder 272 * chain, starting from the first bridge to the last. These are called 273 * after completing the encoder's commit op. 274 * 275 * Note that the bridge passed should be the one closest to the encoder 276 */ 277 void drm_bridge_enable(struct drm_bridge *bridge) 278 { 279 if (!bridge) 280 return; 281 282 if (bridge->funcs->enable) 283 bridge->funcs->enable(bridge); 284 285 drm_bridge_enable(bridge->next); 286 } 287 EXPORT_SYMBOL(drm_bridge_enable); 288 289 #ifdef CONFIG_OF 290 /** 291 * of_drm_find_bridge - find the bridge corresponding to the device node in 292 * the global bridge list 293 * 294 * @np: device node 295 * 296 * RETURNS: 297 * drm_bridge control struct on success, NULL on failure 298 */ 299 struct drm_bridge *of_drm_find_bridge(struct device_node *np) 300 { 301 struct drm_bridge *bridge; 302 303 mutex_lock(&bridge_lock); 304 305 list_for_each_entry(bridge, &bridge_list, list) { 306 if (bridge->of_node == np) { 307 mutex_unlock(&bridge_lock); 308 return bridge; 309 } 310 } 311 312 mutex_unlock(&bridge_lock); 313 return NULL; 314 } 315 EXPORT_SYMBOL(of_drm_find_bridge); 316 #endif 317 318 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>"); 319 MODULE_DESCRIPTION("DRM bridge infrastructure"); 320 MODULE_LICENSE("GPL and additional rights"); 321