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  * 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");