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 #include <linux/mutex.h> 27 28 #include <drm/drm_bridge.h> 29 #include <drm/drm_encoder.h> 30 31 #include "drm_crtc_internal.h" 32 33 /** 34 * DOC: overview 35 * 36 * &struct drm_bridge represents a device that hangs on to an encoder. These are 37 * handy when a regular &drm_encoder entity isn't enough to represent the entire 38 * encoder chain. 39 * 40 * A bridge is always attached to a single &drm_encoder at a time, but can be 41 * either connected to it directly, or through an intermediate bridge:: 42 * 43 * encoder ---> bridge B ---> bridge A 44 * 45 * Here, the output of the encoder feeds to bridge B, and that furthers feeds to 46 * bridge A. 47 * 48 * The driver using the bridge is responsible to make the associations between 49 * the encoder and bridges. Once these links are made, the bridges will 50 * participate along with encoder functions to perform mode_set/enable/disable 51 * through the ops provided in &drm_bridge_funcs. 52 * 53 * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes, 54 * CRTCs, encoders or connectors and hence are not visible to userspace. They 55 * just provide additional hooks to get the desired output at the end of the 56 * encoder chain. 57 * 58 * Bridges can also be chained up using the &drm_bridge.next pointer. 59 * 60 * Both legacy CRTC helpers and the new atomic modeset helpers support bridges. 61 */ 62 63 static DEFINE_MUTEX(bridge_lock); 64 static LINUX_LIST_HEAD(bridge_list); 65 66 /** 67 * drm_bridge_add - add the given bridge to the global bridge list 68 * 69 * @bridge: bridge control structure 70 */ 71 void drm_bridge_add(struct drm_bridge *bridge) 72 { 73 mutex_lock(&bridge_lock); 74 list_add_tail(&bridge->list, &bridge_list); 75 mutex_unlock(&bridge_lock); 76 } 77 EXPORT_SYMBOL(drm_bridge_add); 78 79 /** 80 * drm_bridge_remove - remove the given bridge from the global bridge list 81 * 82 * @bridge: bridge control structure 83 */ 84 void drm_bridge_remove(struct drm_bridge *bridge) 85 { 86 mutex_lock(&bridge_lock); 87 list_del_init(&bridge->list); 88 mutex_unlock(&bridge_lock); 89 } 90 EXPORT_SYMBOL(drm_bridge_remove); 91 92 /** 93 * drm_bridge_attach - attach the bridge to an encoder's chain 94 * 95 * @encoder: DRM encoder 96 * @bridge: bridge to attach 97 * @previous: previous bridge in the chain (optional) 98 * 99 * Called by a kms driver to link the bridge to an encoder's chain. The previous 100 * argument specifies the previous bridge in the chain. If NULL, the bridge is 101 * linked directly at the encoder's output. Otherwise it is linked at the 102 * previous bridge's output. 103 * 104 * If non-NULL the previous bridge must be already attached by a call to this 105 * function. 106 * 107 * RETURNS: 108 * Zero on success, error code on failure 109 */ 110 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge, 111 struct drm_bridge *previous) 112 { 113 int ret; 114 115 if (!encoder || !bridge) 116 return -EINVAL; 117 118 if (previous && (!previous->dev || previous->encoder != encoder)) 119 return -EINVAL; 120 121 if (bridge->dev) 122 return -EBUSY; 123 124 bridge->dev = encoder->dev; 125 bridge->encoder = encoder; 126 127 if (bridge->funcs->attach) { 128 ret = bridge->funcs->attach(bridge); 129 if (ret < 0) { 130 bridge->dev = NULL; 131 bridge->encoder = NULL; 132 return ret; 133 } 134 } 135 136 if (previous) 137 previous->next = bridge; 138 else 139 encoder->bridge = bridge; 140 141 return 0; 142 } 143 EXPORT_SYMBOL(drm_bridge_attach); 144 145 void drm_bridge_detach(struct drm_bridge *bridge) 146 { 147 if (WARN_ON(!bridge)) 148 return; 149 150 if (WARN_ON(!bridge->dev)) 151 return; 152 153 if (bridge->funcs->detach) 154 bridge->funcs->detach(bridge); 155 156 bridge->dev = NULL; 157 } 158 159 /** 160 * DOC: bridge callbacks 161 * 162 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM 163 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c 164 * These helpers call a specific &drm_bridge_funcs op for all the bridges 165 * during encoder configuration. 166 * 167 * For detailed specification of the bridge callbacks see &drm_bridge_funcs. 168 */ 169 170 /** 171 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the 172 * encoder chain 173 * @bridge: bridge control structure 174 * @mode: desired mode to be set for the bridge 175 * @adjusted_mode: updated mode that works for this bridge 176 * 177 * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the 178 * encoder chain, starting from the first bridge to the last. 179 * 180 * Note: the bridge passed should be the one closest to the encoder 181 * 182 * RETURNS: 183 * true on success, false on failure 184 */ 185 bool drm_bridge_mode_fixup(struct drm_bridge *bridge, 186 const struct drm_display_mode *mode, 187 struct drm_display_mode *adjusted_mode) 188 { 189 bool ret = true; 190 191 if (!bridge) 192 return true; 193 194 if (bridge->funcs->mode_fixup) 195 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode); 196 197 ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode); 198 199 return ret; 200 } 201 EXPORT_SYMBOL(drm_bridge_mode_fixup); 202 203 /** 204 * drm_bridge_mode_valid - validate the mode against all bridges in the 205 * encoder chain. 206 * @bridge: bridge control structure 207 * @mode: desired mode to be validated 208 * 209 * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder 210 * chain, starting from the first bridge to the last. If at least one bridge 211 * does not accept the mode the function returns the error code. 212 * 213 * Note: the bridge passed should be the one closest to the encoder. 214 * 215 * RETURNS: 216 * MODE_OK on success, drm_mode_status Enum error code on failure 217 */ 218 enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge, 219 const struct drm_display_mode *mode) 220 { 221 enum drm_mode_status ret = MODE_OK; 222 223 if (!bridge) 224 return ret; 225 226 if (bridge->funcs->mode_valid) 227 ret = bridge->funcs->mode_valid(bridge, mode); 228 229 if (ret != MODE_OK) 230 return ret; 231 232 return drm_bridge_mode_valid(bridge->next, mode); 233 } 234 EXPORT_SYMBOL(drm_bridge_mode_valid); 235 236 /** 237 * drm_bridge_disable - disables all bridges in the encoder chain 238 * @bridge: bridge control structure 239 * 240 * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder 241 * chain, starting from the last bridge to the first. These are called before 242 * calling the encoder's prepare op. 243 * 244 * Note: the bridge passed should be the one closest to the encoder 245 */ 246 void drm_bridge_disable(struct drm_bridge *bridge) 247 { 248 if (!bridge) 249 return; 250 251 drm_bridge_disable(bridge->next); 252 253 if (bridge->funcs->disable) 254 bridge->funcs->disable(bridge); 255 } 256 EXPORT_SYMBOL(drm_bridge_disable); 257 258 /** 259 * drm_bridge_post_disable - cleans up after disabling all bridges in the encoder chain 260 * @bridge: bridge control structure 261 * 262 * Calls &drm_bridge_funcs.post_disable op for all the bridges in the 263 * encoder chain, starting from the first bridge to the last. These are called 264 * after completing the encoder's prepare op. 265 * 266 * Note: the bridge passed should be the one closest to the encoder 267 */ 268 void drm_bridge_post_disable(struct drm_bridge *bridge) 269 { 270 if (!bridge) 271 return; 272 273 if (bridge->funcs->post_disable) 274 bridge->funcs->post_disable(bridge); 275 276 drm_bridge_post_disable(bridge->next); 277 } 278 EXPORT_SYMBOL(drm_bridge_post_disable); 279 280 /** 281 * drm_bridge_mode_set - set proposed mode for all bridges in the 282 * encoder chain 283 * @bridge: bridge control structure 284 * @mode: desired mode to be set for the bridge 285 * @adjusted_mode: updated mode that works for this bridge 286 * 287 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the 288 * encoder chain, starting from the first bridge to the last. 289 * 290 * Note: the bridge passed should be the one closest to the encoder 291 */ 292 void drm_bridge_mode_set(struct drm_bridge *bridge, 293 struct drm_display_mode *mode, 294 struct drm_display_mode *adjusted_mode) 295 { 296 if (!bridge) 297 return; 298 299 if (bridge->funcs->mode_set) 300 bridge->funcs->mode_set(bridge, mode, adjusted_mode); 301 302 drm_bridge_mode_set(bridge->next, mode, adjusted_mode); 303 } 304 EXPORT_SYMBOL(drm_bridge_mode_set); 305 306 /** 307 * drm_bridge_pre_enable - prepares for enabling all 308 * bridges in the encoder chain 309 * @bridge: bridge control structure 310 * 311 * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder 312 * chain, starting from the last bridge to the first. These are called 313 * before calling the encoder's commit op. 314 * 315 * Note: the bridge passed should be the one closest to the encoder 316 */ 317 void drm_bridge_pre_enable(struct drm_bridge *bridge) 318 { 319 if (!bridge) 320 return; 321 322 drm_bridge_pre_enable(bridge->next); 323 324 if (bridge->funcs->pre_enable) 325 bridge->funcs->pre_enable(bridge); 326 } 327 EXPORT_SYMBOL(drm_bridge_pre_enable); 328 329 /** 330 * drm_bridge_enable - enables all bridges in the encoder chain 331 * @bridge: bridge control structure 332 * 333 * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder 334 * chain, starting from the first bridge to the last. These are called 335 * after completing the encoder's commit op. 336 * 337 * Note that the bridge passed should be the one closest to the encoder 338 */ 339 void drm_bridge_enable(struct drm_bridge *bridge) 340 { 341 if (!bridge) 342 return; 343 344 if (bridge->funcs->enable) 345 bridge->funcs->enable(bridge); 346 347 drm_bridge_enable(bridge->next); 348 } 349 EXPORT_SYMBOL(drm_bridge_enable); 350 351 #ifdef CONFIG_OF 352 /** 353 * of_drm_find_bridge - find the bridge corresponding to the device node in 354 * the global bridge list 355 * 356 * @np: device node 357 * 358 * RETURNS: 359 * drm_bridge control struct on success, NULL on failure 360 */ 361 struct drm_bridge *of_drm_find_bridge(struct device_node *np) 362 { 363 struct drm_bridge *bridge; 364 365 mutex_lock(&bridge_lock); 366 367 list_for_each_entry(bridge, &bridge_list, list) { 368 if (bridge->of_node == np) { 369 mutex_unlock(&bridge_lock); 370 return bridge; 371 } 372 } 373 374 mutex_unlock(&bridge_lock); 375 return NULL; 376 } 377 EXPORT_SYMBOL(of_drm_find_bridge); 378 #endif 379 380 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>"); 381 MODULE_DESCRIPTION("DRM bridge infrastructure"); 382