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