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