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  * drm_bridge represents a device that hangs on to an encoder. These are handy
  34  * when a regular drm_encoder entity isn't enough to represent the entire
  35  * encoder chain.
  36  *
  37  * A bridge is always associated 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. They just provide additional hooks to get the
  52  * desired output at the end of the encoder chain.
  53  */
  54
  55 static DEFINE_MUTEX(bridge_lock);
  56 static LINUX_LIST_HEAD(bridge_list);
  57
  58 /**
  59  * drm_bridge_add - add the given bridge to the global bridge list
  60  *
  61  * @bridge: bridge control structure
  62  *
  63  * RETURNS:
  64  * Unconditionally returns Zero.
  65  */
  66 int drm_bridge_add(struct drm_bridge *bridge)
  67 {
  68         mutex_lock(&bridge_lock);
  69         list_add_tail(&bridge->list, &bridge_list);
  70         mutex_unlock(&bridge_lock);
  71
  72         return 0;
  73 }
  74 EXPORT_SYMBOL(drm_bridge_add);
  75
  76 /**
  77  * drm_bridge_remove - remove the given bridge from the global bridge list
  78  *
  79  * @bridge: bridge control structure
  80  */
  81 void drm_bridge_remove(struct drm_bridge *bridge)
  82 {
  83         mutex_lock(&bridge_lock);
  84         list_del_init(&bridge->list);
  85         mutex_unlock(&bridge_lock);
  86 }
  87 EXPORT_SYMBOL(drm_bridge_remove);
  88
  89 /**
  90  * drm_bridge_attach - associate given bridge to our DRM device
  91  *
  92  * @dev: DRM device
  93  * @bridge: bridge control structure
  94  *
  95  * called by a kms driver to link one of our encoder/bridge to the given
  96  * bridge.
  97  *
  98  * Note that setting up links between the bridge and our encoder/bridge
  99  * objects needs to be handled by the kms driver itself
 100  *
 101  * RETURNS:
 102  * Zero on success, error code on failure
 103  */
 104 int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
 105 {
 106         if (!dev || !bridge)
 107                 return -EINVAL;
 108
 109         if (bridge->dev)
 110                 return -EBUSY;
 111
 112         bridge->dev = dev;
 113
 114         if (bridge->funcs->attach)
 115                 return bridge->funcs->attach(bridge);
 116
 117         return 0;
 118 }
 119 EXPORT_SYMBOL(drm_bridge_attach);
 120
 121 /**
 122  * DOC: bridge callbacks
 123  *
 124  * The drm_bridge_funcs ops are populated by the bridge driver. The drm
 125  * internals(atomic and crtc helpers) use the helpers defined in drm_bridge.c
 126  * These helpers call a specific drm_bridge_funcs op for all the bridges
 127  * during encoder configuration.
 128  *
 129  * When creating a bridge driver, one can implement drm_bridge_funcs op with
 130  * the help of these rough rules:
 131  *
 132  * pre_enable: this contains things needed to be done for the bridge before
 133  * its clock and timings are enabled by its source. For a bridge, its source
 134  * is generally the encoder or bridge just before it in the encoder chain.
 135  *
 136  * enable: this contains things needed to be done for the bridge once its
 137  * source is enabled. In other words, enable is called once the source is
 138  * ready with clock and timing needed by the bridge.
 139  *
 140  * disable: this contains things needed to be done for the bridge assuming
 141  * that its source is still enabled, i.e. clock and timings are still on.
 142  *
 143  * post_disable: this contains things needed to be done for the bridge once
 144  * its source is disabled, i.e. once clocks and timings are off.
 145  *
 146  * mode_fixup: this should fixup the given mode for the bridge. It is called
 147  * after the encoder's mode fixup. mode_fixup can also reject a mode completely
 148  * if it's unsuitable for the hardware.
 149  *
 150  * mode_set: this sets up the mode for the bridge. It assumes that its source
 151  * (an encoder or a bridge) has set the mode too.
 152  */
 153
 154 /**
 155  * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the
 156  *                         encoder chain
 157  * @bridge: bridge control structure
 158  * @mode: desired mode to be set for the bridge
 159  * @adjusted_mode: updated mode that works for this bridge
 160  *
 161  * Calls 'mode_fixup' drm_bridge_funcs op for all the bridges in the
 162  * encoder chain, starting from the first bridge to the last.
 163  *
 164  * Note: the bridge passed should be the one closest to the encoder
 165  *
 166  * RETURNS:
 167  * true on success, false on failure
 168  */
 169 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
 170                         const struct drm_display_mode *mode,
 171                         struct drm_display_mode *adjusted_mode)
 172 {
 173         bool ret = true;
 174
 175         if (!bridge)
 176                 return true;
 177
 178         if (bridge->funcs->mode_fixup)
 179                 ret = bridge->funcs->mode_fixup(bridge, mode, adjusted_mode);
 180
 181         ret = ret && drm_bridge_mode_fixup(bridge->next, mode, adjusted_mode);
 182
 183         return ret;
 184 }
 185 EXPORT_SYMBOL(drm_bridge_mode_fixup);
 186
 187 /**
 188  * drm_bridge_disable - calls 'disable' drm_bridge_funcs op for all
 189  *                      bridges in the encoder chain.
 190  * @bridge: bridge control structure
 191  *
 192  * Calls 'disable' drm_bridge_funcs op for all the bridges in the encoder
 193  * chain, starting from the last bridge to the first. These are called before
 194  * calling the encoder's prepare op.
 195  *
 196  * Note: the bridge passed should be the one closest to the encoder
 197  */
 198 void drm_bridge_disable(struct drm_bridge *bridge)
 199 {
 200         if (!bridge)
 201                 return;
 202
 203         drm_bridge_disable(bridge->next);
 204
 205         bridge->funcs->disable(bridge);
 206 }
 207 EXPORT_SYMBOL(drm_bridge_disable);
 208
 209 /**
 210  * drm_bridge_post_disable - calls 'post_disable' drm_bridge_funcs op for
 211  *                           all bridges in the encoder chain.
 212  * @bridge: bridge control structure
 213  *
 214  * Calls 'post_disable' drm_bridge_funcs op for all the bridges in the
 215  * encoder chain, starting from the first bridge to the last. These are called
 216  * after completing the encoder's prepare op.
 217  *
 218  * Note: the bridge passed should be the one closest to the encoder
 219  */
 220 void drm_bridge_post_disable(struct drm_bridge *bridge)
 221 {
 222         if (!bridge)
 223                 return;
 224
 225         bridge->funcs->post_disable(bridge);
 226
 227         drm_bridge_post_disable(bridge->next);
 228 }
 229 EXPORT_SYMBOL(drm_bridge_post_disable);
 230
 231 /**
 232  * drm_bridge_mode_set - set proposed mode for all bridges in the
 233  *                       encoder chain
 234  * @bridge: bridge control structure
 235  * @mode: desired mode to be set for the bridge
 236  * @adjusted_mode: updated mode that works for this bridge
 237  *
 238  * Calls 'mode_set' drm_bridge_funcs op for all the bridges in the
 239  * encoder chain, starting from the first bridge to the last.
 240  *
 241  * Note: the bridge passed should be the one closest to the encoder
 242  */
 243 void drm_bridge_mode_set(struct drm_bridge *bridge,
 244                         struct drm_display_mode *mode,
 245                         struct drm_display_mode *adjusted_mode)
 246 {
 247         if (!bridge)
 248                 return;
 249
 250         if (bridge->funcs->mode_set)
 251                 bridge->funcs->mode_set(bridge, mode, adjusted_mode);
 252
 253         drm_bridge_mode_set(bridge->next, mode, adjusted_mode);
 254 }
 255 EXPORT_SYMBOL(drm_bridge_mode_set);
 256
 257 /**
 258  * drm_bridge_pre_enable - calls 'pre_enable' drm_bridge_funcs op for all
 259  *                         bridges in the encoder chain.
 260  * @bridge: bridge control structure
 261  *
 262  * Calls 'pre_enable' drm_bridge_funcs op for all the bridges in the encoder
 263  * chain, starting from the last bridge to the first. These are called
 264  * before calling the encoder's commit op.
 265  *
 266  * Note: the bridge passed should be the one closest to the encoder
 267  */
 268 void drm_bridge_pre_enable(struct drm_bridge *bridge)
 269 {
 270         if (!bridge)
 271                 return;
 272
 273         drm_bridge_pre_enable(bridge->next);
 274
 275         bridge->funcs->pre_enable(bridge);
 276 }
 277 EXPORT_SYMBOL(drm_bridge_pre_enable);
 278
 279 /**
 280  * drm_bridge_enable - calls 'enable' drm_bridge_funcs op for all bridges
 281  *                     in the encoder chain.
 282  * @bridge: bridge control structure
 283  *
 284  * Calls 'enable' drm_bridge_funcs op for all the bridges in the encoder
 285  * chain, starting from the first bridge to the last. These are called
 286  * after completing the encoder's commit op.
 287  *
 288  * Note that the bridge passed should be the one closest to the encoder
 289  */
 290 void drm_bridge_enable(struct drm_bridge *bridge)
 291 {
 292         if (!bridge)
 293                 return;
 294
 295         bridge->funcs->enable(bridge);
 296
 297         drm_bridge_enable(bridge->next);
 298 }
 299 EXPORT_SYMBOL(drm_bridge_enable);
 300
 301 #ifdef CONFIG_OF
 302 /**
 303  * of_drm_find_bridge - find the bridge corresponding to the device node in
 304  *                      the global bridge list
 305  *
 306  * @np: device node
 307  *
 308  * RETURNS:
 309  * drm_bridge control struct on success, NULL on failure
 310  */
 311 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 312 {
 313         struct drm_bridge *bridge;
 314
 315         mutex_lock(&bridge_lock);
 316
 317         list_for_each_entry(bridge, &bridge_list, list) {
 318                 if (bridge->of_node == np) {
 319                         mutex_unlock(&bridge_lock);
 320                         return bridge;
 321                 }
 322         }
 323
 324         mutex_unlock(&bridge_lock);
 325         return NULL;
 326 }
 327 EXPORT_SYMBOL(of_drm_find_bridge);
 328 #endif
 329
 330 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
 331 MODULE_DESCRIPTION("DRM bridge infrastructure");