drivers/gpu/drm/drm_bridge.c

   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  * drm_bridge_detach - deassociate given bridge from its DRM device
 129  *
 130  * @bridge: bridge control structure
 131  *
 132  * Called by a kms driver to unlink the given bridge from its DRM device.
 133  *
 134  * Note that tearing down links between the bridge and our encoder/bridge
 135  * objects needs to be handled by the kms driver itself.
 136  */
 137 void drm_bridge_detach(struct drm_bridge *bridge)
 138 {
 139         if (WARN_ON(!bridge))
 140                 return;
 141
 142         if (WARN_ON(!bridge->dev))
 143                 return;
 144
 145         if (bridge->funcs->detach)
 146                 bridge->funcs->detach(bridge);
 147
 148         bridge->dev = NULL;
 149 }
 150 EXPORT_SYMBOL(drm_bridge_detach);
 151
 152 /**
 153  * DOC: bridge callbacks
 154  *
 155  * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
 156  * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c
 157  * These helpers call a specific &drm_bridge_funcs op for all the bridges
 158  * during encoder configuration.
 159  *
 160  * For detailed specification of the bridge callbacks see &drm_bridge_funcs.
 161  */
 162
 163 /**
 164  * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
 165  *                         encoder chain
 166  * @bridge: bridge control structure
 167  * @mode: desired mode to be set for the bridge
 168  * @adjusted_mode: updated mode that works for this bridge
 169  *
 170  * Calls ->mode_fixup() &drm_bridge_funcs op for all the bridges in the
 171  * encoder chain, starting from the first bridge to the last.
 172  *
 173  * Note: the bridge passed should be the one closest to the encoder
 174  *
 175  * RETURNS:
 176  * true on success, false on failure
 177  */
 178 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
 179                         const struct drm_display_mode *mode,
 180                         struct drm_display_mode *adjusted_mode)
 181 {
 182         bool ret = true;
 183
 184         if (!bridge)
 185                 return true;
 186
 187         if (bridge->funcs->mode_fixup)
 188                 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
 189
 190         ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
 191
 192         return ret;
 193 }
 194 EXPORT_SYMBOL(drm_bridge_mode_fixup);
 195
 196 /**
 197  * drm_bridge_disable - calls ->disable() &drm_bridge_funcs op for all
 198  *                      bridges in the encoder chain.
 199  * @bridge: bridge control structure
 200  *
 201  * Calls ->disable() &drm_bridge_funcs op for all the bridges in the encoder
 202  * chain, starting from the last bridge to the first. These are called before
 203  * calling the encoder's prepare op.
 204  *
 205  * Note: the bridge passed should be the one closest to the encoder
 206  */
 207 void drm_bridge_disable(struct drm_bridge *bridge)
 208 {
 209         if (!bridge)
 210                 return;
 211
 212         drm_bridge_disable(bridge->next);
 213
 214         if (bridge->funcs->disable)
 215                 bridge->funcs->disable(bridge);
 216 }
 217 EXPORT_SYMBOL(drm_bridge_disable);
 218
 219 /**
 220  * drm_bridge_post_disable - calls ->post_disable() &drm_bridge_funcs op for
 221  *                           all bridges in the encoder chain.
 222  * @bridge: bridge control structure
 223  *
 224  * Calls ->post_disable() &drm_bridge_funcs op for all the bridges in the
 225  * encoder chain, starting from the first bridge to the last. These are called
 226  * after completing the encoder's prepare op.
 227  *
 228  * Note: the bridge passed should be the one closest to the encoder
 229  */
 230 void drm_bridge_post_disable(struct drm_bridge *bridge)
 231 {
 232         if (!bridge)
 233                 return;
 234
 235         if (bridge->funcs->post_disable)
 236                 bridge->funcs->post_disable(bridge);
 237
 238         drm_bridge_post_disable(bridge->next);
 239 }
 240 EXPORT_SYMBOL(drm_bridge_post_disable);
 241
 242 /**
 243  * drm_bridge_mode_set - set proposed mode for all bridges in the
 244  *                       encoder chain
 245  * @bridge: bridge control structure
 246  * @mode: desired mode to be set for the bridge
 247  * @adjusted_mode: updated mode that works for this bridge
 248  *
 249  * Calls ->mode_set() &drm_bridge_funcs op for all the bridges in the
 250  * encoder chain, starting from the first bridge to the last.
 251  *
 252  * Note: the bridge passed should be the one closest to the encoder
 253  */
 254 void drm_bridge_mode_set(struct drm_bridge *bridge,
 255                         struct drm_display_mode *mode,
 256                         struct drm_display_mode *adjusted_mode)
 257 {
 258         if (!bridge)
 259                 return;
 260
 261         if (bridge->funcs->mode_set)
 262                 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
 263
 264         drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
 265 }
 266 EXPORT_SYMBOL(drm_bridge_mode_set);
 267
 268 /**
 269  * drm_bridge_pre_enable - calls ->pre_enable() &drm_bridge_funcs op for all
 270  *                         bridges in the encoder chain.
 271  * @bridge: bridge control structure
 272  *
 273  * Calls ->pre_enable() &drm_bridge_funcs op for all the bridges in the encoder
 274  * chain, starting from the last bridge to the first. These are called
 275  * before calling the encoder's commit op.
 276  *
 277  * Note: the bridge passed should be the one closest to the encoder
 278  */
 279 void drm_bridge_pre_enable(struct drm_bridge *bridge)
 280 {
 281         if (!bridge)
 282                 return;
 283
 284         drm_bridge_pre_enable(bridge->next);
 285
 286         if (bridge->funcs->pre_enable)
 287                 bridge->funcs->pre_enable(bridge);
 288 }
 289 EXPORT_SYMBOL(drm_bridge_pre_enable);
 290
 291 /**
 292  * drm_bridge_enable - calls ->enable() &drm_bridge_funcs op for all bridges
 293  *                     in the encoder chain.
 294  * @bridge: bridge control structure
 295  *
 296  * Calls ->enable() &drm_bridge_funcs op for all the bridges in the encoder
 297  * chain, starting from the first bridge to the last. These are called
 298  * after completing the encoder's commit op.
 299  *
 300  * Note that the bridge passed should be the one closest to the encoder
 301  */
 302 void drm_bridge_enable(struct drm_bridge *bridge)
 303 {
 304         if (!bridge)
 305                 return;
 306
 307         if (bridge->funcs->enable)
 308                 bridge->funcs->enable(bridge);
 309
 310         drm_bridge_enable(bridge->next);
 311 }
 312 EXPORT_SYMBOL(drm_bridge_enable);
 313
 314 #ifdef CONFIG_OF
 315 /**
 316  * of_drm_find_bridge - find the bridge corresponding to the device node in
 317  *                      the global bridge list
 318  *
 319  * @np: device node
 320  *
 321  * RETURNS:
 322  * drm_bridge control struct on success, NULL on failure
 323  */
 324 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 325 {
 326         struct drm_bridge *bridge;
 327
 328         mutex_lock(&bridge_lock);
 329
 330         list_for_each_entry(bridge, &bridge_list, list) {
 331                 if (bridge->of_node == np) {
 332                         mutex_unlock(&bridge_lock);
 333                         return bridge;
 334                 }
 335         }
 336
 337         mutex_unlock(&bridge_lock);
 338         return NULL;
 339 }
 340 EXPORT_SYMBOL(of_drm_find_bridge);
 341 #endif
 342
 343 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
 344 MODULE_DESCRIPTION("DRM bridge infrastructure");
 345 MODULE_LICENSE("GPL and additional rights");