sys/dev/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
  28 #include "drm/drmP.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 LINUX_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  * DOC: bridge callbacks
 128  *
 129  * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
 130  * internals (atomic and CRTC helpers) use the helpers defined in drm_bridge.c
 131  * These helpers call a specific &drm_bridge_funcs op for all the bridges
 132  * during encoder configuration.
 133  *
 134  * For detailed specification of the bridge callbacks see &drm_bridge_funcs.
 135  */
 136
 137 /**
 138  * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
 139  *                         encoder chain
 140  * @bridge: bridge control structure
 141  * @mode: desired mode to be set for the bridge
 142  * @adjusted_mode: updated mode that works for this bridge
 143  *
 144  * Calls ->mode_fixup() &drm_bridge_funcs op for all the bridges in the
 145  * encoder chain, starting from the first bridge to the last.
 146  *
 147  * Note: the bridge passed should be the one closest to the encoder
 148  *
 149  * RETURNS:
 150  * true on success, false on failure
 151  */
 152 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
 153                         const struct drm_display_mode *mode,
 154                         struct drm_display_mode *adjusted_mode)
 155 {
 156         bool ret = true;
 157
 158         if (!bridge)
 159                 return true;
 160
 161         if (bridge->funcs->mode_fixup)
 162                 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
 163
 164         ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
 165
 166         return ret;
 167 }
 168 EXPORT_SYMBOL(drm_bridge_mode_fixup);
 169
 170 /**
 171  * drm_bridge_disable - calls ->disable() &drm_bridge_funcs op for all
 172  *                      bridges in the encoder chain.
 173  * @bridge: bridge control structure
 174  *
 175  * Calls ->disable() &drm_bridge_funcs op for all the bridges in the encoder
 176  * chain, starting from the last bridge to the first. These are called before
 177  * calling the encoder's prepare op.
 178  *
 179  * Note: the bridge passed should be the one closest to the encoder
 180  */
 181 void drm_bridge_disable(struct drm_bridge *bridge)
 182 {
 183         if (!bridge)
 184                 return;
 185
 186         drm_bridge_disable(bridge->next);
 187
 188         if (bridge->funcs->disable)
 189                 bridge->funcs->disable(bridge);
 190 }
 191 EXPORT_SYMBOL(drm_bridge_disable);
 192
 193 /**
 194  * drm_bridge_post_disable - calls ->post_disable() &drm_bridge_funcs op for
 195  *                           all bridges in the encoder chain.
 196  * @bridge: bridge control structure
 197  *
 198  * Calls ->post_disable() &drm_bridge_funcs op for all the bridges in the
 199  * encoder chain, starting from the first bridge to the last. These are called
 200  * after completing the encoder's prepare op.
 201  *
 202  * Note: the bridge passed should be the one closest to the encoder
 203  */
 204 void drm_bridge_post_disable(struct drm_bridge *bridge)
 205 {
 206         if (!bridge)
 207                 return;
 208
 209         if (bridge->funcs->post_disable)
 210                 bridge->funcs->post_disable(bridge);
 211
 212         drm_bridge_post_disable(bridge->next);
 213 }
 214 EXPORT_SYMBOL(drm_bridge_post_disable);
 215
 216 /**
 217  * drm_bridge_mode_set - set proposed mode for all bridges in the
 218  *                       encoder chain
 219  * @bridge: bridge control structure
 220  * @mode: desired mode to be set for the bridge
 221  * @adjusted_mode: updated mode that works for this bridge
 222  *
 223  * Calls ->mode_set() &drm_bridge_funcs op for all the bridges in the
 224  * encoder chain, starting from the first bridge to the last.
 225  *
 226  * Note: the bridge passed should be the one closest to the encoder
 227  */
 228 void drm_bridge_mode_set(struct drm_bridge *bridge,
 229                         struct drm_display_mode *mode,
 230                         struct drm_display_mode *adjusted_mode)
 231 {
 232         if (!bridge)
 233                 return;
 234
 235         if (bridge->funcs->mode_set)
 236                 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
 237
 238         drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
 239 }
 240 EXPORT_SYMBOL(drm_bridge_mode_set);
 241
 242 /**
 243  * drm_bridge_pre_enable - calls ->pre_enable() &drm_bridge_funcs op for all
 244  *                         bridges in the encoder chain.
 245  * @bridge: bridge control structure
 246  *
 247  * Calls ->pre_enable() &drm_bridge_funcs op for all the bridges in the encoder
 248  * chain, starting from the last bridge to the first. These are called
 249  * before calling the encoder's commit op.
 250  *
 251  * Note: the bridge passed should be the one closest to the encoder
 252  */
 253 void drm_bridge_pre_enable(struct drm_bridge *bridge)
 254 {
 255         if (!bridge)
 256                 return;
 257
 258         drm_bridge_pre_enable(bridge->next);
 259
 260         if (bridge->funcs->pre_enable)
 261                 bridge->funcs->pre_enable(bridge);
 262 }
 263 EXPORT_SYMBOL(drm_bridge_pre_enable);
 264
 265 /**
 266  * drm_bridge_enable - calls ->enable() &drm_bridge_funcs op for all bridges
 267  *                     in the encoder chain.
 268  * @bridge: bridge control structure
 269  *
 270  * Calls ->enable() &drm_bridge_funcs op for all the bridges in the encoder
 271  * chain, starting from the first bridge to the last. These are called
 272  * after completing the encoder's commit op.
 273  *
 274  * Note that the bridge passed should be the one closest to the encoder
 275  */
 276 void drm_bridge_enable(struct drm_bridge *bridge)
 277 {
 278         if (!bridge)
 279                 return;
 280
 281         if (bridge->funcs->enable)
 282                 bridge->funcs->enable(bridge);
 283
 284         drm_bridge_enable(bridge->next);
 285 }
 286 EXPORT_SYMBOL(drm_bridge_enable);
 287
 288 #ifdef CONFIG_OF
 289 /**
 290  * of_drm_find_bridge - find the bridge corresponding to the device node in
 291  *                      the global bridge list
 292  *
 293  * @np: device node
 294  *
 295  * RETURNS:
 296  * drm_bridge control struct on success, NULL on failure
 297  */
 298 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 299 {
 300         struct drm_bridge *bridge;
 301
 302         mutex_lock(&bridge_lock);
 303
 304         list_for_each_entry(bridge, &bridge_list, list) {
 305                 if (bridge->of_node == np) {
 306                         mutex_unlock(&bridge_lock);
 307                         return bridge;
 308                 }
 309         }
 310
 311         mutex_unlock(&bridge_lock);
 312         return NULL;
 313 }
 314 EXPORT_SYMBOL(of_drm_find_bridge);
 315 #endif
 316
 317 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
 318 MODULE_DESCRIPTION("DRM bridge infrastructure");