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 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 * RETURNS: 72 * Unconditionally returns Zero. 73 */ 74 int drm_bridge_add(struct drm_bridge *bridge) 75 { 76 mutex_lock(&bridge_lock); 77 list_add_tail(&bridge->list, &bridge_list); 78 mutex_unlock(&bridge_lock); 79 80 return 0; 81 } 82 EXPORT_SYMBOL(drm_bridge_add); 83 84 /** 85 * drm_bridge_remove - remove the given bridge from the global bridge list 86 * 87 * @bridge: bridge control structure 88 */ 89 void drm_bridge_remove(struct drm_bridge *bridge) 90 { 91 mutex_lock(&bridge_lock); 92 list_del_init(&bridge->list); 93 mutex_unlock(&bridge_lock); 94 } 95 EXPORT_SYMBOL(drm_bridge_remove); 96 97 /** 98 * drm_bridge_attach - attach the bridge to an encoder's chain 99 * 100 * @encoder: DRM encoder 101 * @bridge: bridge to attach 102 * @previous: previous bridge in the chain (optional) 103 * 104 * Called by a kms driver to link the bridge to an encoder's chain. The previous 105 * argument specifies the previous bridge in the chain. If NULL, the bridge is 106 * linked directly at the encoder's output. Otherwise it is linked at the 107 * previous bridge's output. 108 * 109 * If non-NULL the previous bridge must be already attached by a call to this 110 * function. 111 * 112 * RETURNS: 113 * Zero on success, error code on failure 114 */ 115 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge, 116 struct drm_bridge *previous) 117 { 118 int ret; 119 120 if (!encoder || !bridge) 121 return -EINVAL; 122 123 if (previous && (!previous->dev || previous->encoder != encoder)) 124 return -EINVAL; 125 126 if (bridge->dev) 127 return -EBUSY; 128 129 bridge->dev = encoder->dev; 130 bridge->encoder = encoder; 131 132 if (bridge->funcs->attach) { 133 ret = bridge->funcs->attach(bridge); 134 if (ret < 0) { 135 bridge->dev = NULL; 136 bridge->encoder = NULL; 137 return ret; 138 } 139 } 140 141 if (previous) 142 previous->next = bridge; 143 else 144 encoder->bridge = bridge; 145 146 return 0; 147 } 148 EXPORT_SYMBOL(drm_bridge_attach); 149 150 void drm_bridge_detach(struct drm_bridge *bridge) 151 { 152 if (WARN_ON(!bridge)) 153 return; 154 155 if (WARN_ON(!bridge->dev)) 156 return; 157 158 if (bridge->funcs->detach) 159 bridge->funcs->detach(bridge); 160 161 bridge->dev = NULL; 162 } 163 164 /** 165 * DOC: bridge callbacks 166 * 167 * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM 168 * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c 169 * These helpers call a specific &drm_bridge_funcs op for all the bridges 170 * during encoder configuration. 171 * 172 * For detailed specification of the bridge callbacks see &drm_bridge_funcs. 173 */ 174 175 /** 176 * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the 177 * encoder chain 178 * @bridge: bridge control structure 179 * @mode: desired mode to be set for the bridge 180 * @adjusted_mode: updated mode that works for this bridge 181 * 182 * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the 183 * encoder chain, starting from the first bridge to the last. 184 * 185 * Note: the bridge passed should be the one closest to the encoder 186 * 187 * RETURNS: 188 * true on success, false on failure 189 */ 190 bool drm_bridge_mode_fixup(struct drm_bridge *bridge, 191 const struct drm_display_mode *mode, 192 struct drm_display_mode *adjusted_mode) 193 { 194 bool ret = true; 195 196 if (!bridge) 197 return true; 198 199 if (bridge->funcs->mode_fixup) 200 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode); 201 202 ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode); 203 204 return ret; 205 } 206 EXPORT_SYMBOL(drm_bridge_mode_fixup); 207 208 /** 209 * drm_bridge_disable - disables all bridges in the encoder chain 210 * @bridge: bridge control structure 211 * 212 * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder 213 * chain, starting from the last bridge to the first. These are called before 214 * calling the encoder's prepare op. 215 * 216 * Note: the bridge passed should be the one closest to the encoder 217 */ 218 void drm_bridge_disable(struct drm_bridge *bridge) 219 { 220 if (!bridge) 221 return; 222 223 drm_bridge_disable(bridge->next); 224 225 if (bridge->funcs->disable) 226 bridge->funcs->disable(bridge); 227 } 228 EXPORT_SYMBOL(drm_bridge_disable); 229 230 /** 231 * drm_bridge_post_disable - cleans up after disabling all bridges in the encoder chain 232 * @bridge: bridge control structure 233 * 234 * Calls &drm_bridge_funcs.post_disable op for all the bridges in the 235 * encoder chain, starting from the first bridge to the last. These are called 236 * after completing the encoder's prepare op. 237 * 238 * Note: the bridge passed should be the one closest to the encoder 239 */ 240 void drm_bridge_post_disable(struct drm_bridge *bridge) 241 { 242 if (!bridge) 243 return; 244 245 if (bridge->funcs->post_disable) 246 bridge->funcs->post_disable(bridge); 247 248 drm_bridge_post_disable(bridge->next); 249 } 250 EXPORT_SYMBOL(drm_bridge_post_disable); 251 252 /** 253 * drm_bridge_mode_set - set proposed mode for all bridges in the 254 * encoder chain 255 * @bridge: bridge control structure 256 * @mode: desired mode to be set for the bridge 257 * @adjusted_mode: updated mode that works for this bridge 258 * 259 * Calls &drm_bridge_funcs.mode_set op for all the bridges in the 260 * encoder chain, starting from the first bridge to the last. 261 * 262 * Note: the bridge passed should be the one closest to the encoder 263 */ 264 void drm_bridge_mode_set(struct drm_bridge *bridge, 265 struct drm_display_mode *mode, 266 struct drm_display_mode *adjusted_mode) 267 { 268 if (!bridge) 269 return; 270 271 if (bridge->funcs->mode_set) 272 bridge->funcs->mode_set(bridge, mode, adjusted_mode); 273 274 drm_bridge_mode_set(bridge->next, mode, adjusted_mode); 275 } 276 EXPORT_SYMBOL(drm_bridge_mode_set); 277 278 /** 279 * drm_bridge_pre_enable - prepares for enabling all 280 * bridges in the encoder chain 281 * @bridge: bridge control structure 282 * 283 * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder 284 * chain, starting from the last bridge to the first. These are called 285 * before calling the encoder's commit op. 286 * 287 * Note: the bridge passed should be the one closest to the encoder 288 */ 289 void drm_bridge_pre_enable(struct drm_bridge *bridge) 290 { 291 if (!bridge) 292 return; 293 294 drm_bridge_pre_enable(bridge->next); 295 296 if (bridge->funcs->pre_enable) 297 bridge->funcs->pre_enable(bridge); 298 } 299 EXPORT_SYMBOL(drm_bridge_pre_enable); 300 301 /** 302 * drm_bridge_enable - enables all bridges in the encoder chain 303 * @bridge: bridge control structure 304 * 305 * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder 306 * chain, starting from the first bridge to the last. These are called 307 * after completing the encoder's commit op. 308 * 309 * Note that the bridge passed should be the one closest to the encoder 310 */ 311 void drm_bridge_enable(struct drm_bridge *bridge) 312 { 313 if (!bridge) 314 return; 315 316 if (bridge->funcs->enable) 317 bridge->funcs->enable(bridge); 318 319 drm_bridge_enable(bridge->next); 320 } 321 EXPORT_SYMBOL(drm_bridge_enable); 322 323 #ifdef CONFIG_OF 324 /** 325 * of_drm_find_bridge - find the bridge corresponding to the device node in 326 * the global bridge list 327 * 328 * @np: device node 329 * 330 * RETURNS: 331 * drm_bridge control struct on success, NULL on failure 332 */ 333 struct drm_bridge *of_drm_find_bridge(struct device_node *np) 334 { 335 struct drm_bridge *bridge; 336 337 mutex_lock(&bridge_lock); 338 339 list_for_each_entry(bridge, &bridge_list, list) { 340 if (bridge->of_node == np) { 341 mutex_unlock(&bridge_lock); 342 return bridge; 343 } 344 } 345 346 mutex_unlock(&bridge_lock); 347 return NULL; 348 } 349 EXPORT_SYMBOL(of_drm_find_bridge); 350 #endif 351 352 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>"); 353 MODULE_DESCRIPTION("DRM bridge infrastructure"); 354 MODULE_LICENSE("GPL and additional rights"); 355