1 /*
2  * Copyright (c) 2016 Intel Corporation
3  *
4  * Permission to use, copy, modify, distribute, and sell this software and its
5  * documentation for any purpose is hereby granted without fee, provided that
6  * the above copyright notice appear in all copies and that both that copyright
7  * notice and this permission notice appear in supporting documentation, and
8  * that the name of the copyright holders not be used in advertising or
9  * publicity pertaining to distribution of the software without specific,
10  * written prior permission.  The copyright holders make no representations
11  * about the suitability of this software for any purpose.  It is provided "as
12  * is" without express or implied warranty.
13  *
14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
20  * OF THIS SOFTWARE.
21  */
22 
23 #ifndef __DRM_BRIDGE_H__
24 #define __DRM_BRIDGE_H__
25 
26 #include <linux/ctype.h>
27 #include <linux/list.h>
28 #include <linux/mutex.h>
29 
30 #include <drm/drm_atomic.h>
31 #include <drm/drm_encoder.h>
32 #include <drm/drm_mode_object.h>
33 #include <drm/drm_modes.h>
34 
35 struct drm_bridge;
36 struct drm_bridge_timings;
37 struct drm_connector;
38 struct drm_display_info;
39 struct drm_minor;
40 struct drm_panel;
41 struct edid;
42 struct i2c_adapter;
43 
44 /**
45  * enum drm_bridge_attach_flags - Flags for &drm_bridge_funcs.attach
46  */
47 enum drm_bridge_attach_flags {
48 	/**
49 	 * @DRM_BRIDGE_ATTACH_NO_CONNECTOR: When this flag is set the bridge
50 	 * shall not create a drm_connector.
51 	 */
52 	DRM_BRIDGE_ATTACH_NO_CONNECTOR = BIT(0),
53 };
54 
55 /**
56  * struct drm_bridge_funcs - drm_bridge control functions
57  */
58 struct drm_bridge_funcs {
59 	/**
60 	 * @attach:
61 	 *
62 	 * This callback is invoked whenever our bridge is being attached to a
63 	 * &drm_encoder. The flags argument tunes the behaviour of the attach
64 	 * operation (see DRM_BRIDGE_ATTACH_*).
65 	 *
66 	 * The @attach callback is optional.
67 	 *
68 	 * RETURNS:
69 	 *
70 	 * Zero on success, error code on failure.
71 	 */
72 	int (*attach)(struct drm_bridge *bridge,
73 		      enum drm_bridge_attach_flags flags);
74 
75 	/**
76 	 * @detach:
77 	 *
78 	 * This callback is invoked whenever our bridge is being detached from a
79 	 * &drm_encoder.
80 	 *
81 	 * The @detach callback is optional.
82 	 */
83 	void (*detach)(struct drm_bridge *bridge);
84 
85 	/**
86 	 * @mode_valid:
87 	 *
88 	 * This callback is used to check if a specific mode is valid in this
89 	 * bridge. This should be implemented if the bridge has some sort of
90 	 * restriction in the modes it can display. For example, a given bridge
91 	 * may be responsible to set a clock value. If the clock can not
92 	 * produce all the values for the available modes then this callback
93 	 * can be used to restrict the number of modes to only the ones that
94 	 * can be displayed.
95 	 *
96 	 * This hook is used by the probe helpers to filter the mode list in
97 	 * drm_helper_probe_single_connector_modes(), and it is used by the
98 	 * atomic helpers to validate modes supplied by userspace in
99 	 * drm_atomic_helper_check_modeset().
100 	 *
101 	 * The @mode_valid callback is optional.
102 	 *
103 	 * NOTE:
104 	 *
105 	 * Since this function is both called from the check phase of an atomic
106 	 * commit, and the mode validation in the probe paths it is not allowed
107 	 * to look at anything else but the passed-in mode, and validate it
108 	 * against configuration-invariant hardward constraints. Any further
109 	 * limits which depend upon the configuration can only be checked in
110 	 * @mode_fixup.
111 	 *
112 	 * RETURNS:
113 	 *
114 	 * drm_mode_status Enum
115 	 */
116 	enum drm_mode_status (*mode_valid)(struct drm_bridge *bridge,
117 					   const struct drm_display_info *info,
118 					   const struct drm_display_mode *mode);
119 
120 	/**
121 	 * @mode_fixup:
122 	 *
123 	 * This callback is used to validate and adjust a mode. The parameter
124 	 * mode is the display mode that should be fed to the next element in
125 	 * the display chain, either the final &drm_connector or the next
126 	 * &drm_bridge. The parameter adjusted_mode is the input mode the bridge
127 	 * requires. It can be modified by this callback and does not need to
128 	 * match mode. See also &drm_crtc_state.adjusted_mode for more details.
129 	 *
130 	 * This is the only hook that allows a bridge to reject a modeset. If
131 	 * this function passes all other callbacks must succeed for this
132 	 * configuration.
133 	 *
134 	 * The mode_fixup callback is optional. &drm_bridge_funcs.mode_fixup()
135 	 * is not called when &drm_bridge_funcs.atomic_check() is implemented,
136 	 * so only one of them should be provided.
137 	 *
138 	 * NOTE:
139 	 *
140 	 * This function is called in the check phase of atomic modesets, which
141 	 * can be aborted for any reason (including on userspace's request to
142 	 * just check whether a configuration would be possible). Drivers MUST
143 	 * NOT touch any persistent state (hardware or software) or data
144 	 * structures except the passed in @state parameter.
145 	 *
146 	 * Also beware that userspace can request its own custom modes, neither
147 	 * core nor helpers filter modes to the list of probe modes reported by
148 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
149 	 * that modes are filtered consistently put any bridge constraints and
150 	 * limits checks into @mode_valid.
151 	 *
152 	 * RETURNS:
153 	 *
154 	 * True if an acceptable configuration is possible, false if the modeset
155 	 * operation should be rejected.
156 	 */
157 	bool (*mode_fixup)(struct drm_bridge *bridge,
158 			   const struct drm_display_mode *mode,
159 			   struct drm_display_mode *adjusted_mode);
160 	/**
161 	 * @disable:
162 	 *
163 	 * This callback should disable the bridge. It is called right before
164 	 * the preceding element in the display pipe is disabled. If the
165 	 * preceding element is a bridge this means it's called before that
166 	 * bridge's @disable vfunc. If the preceding element is a &drm_encoder
167 	 * it's called right before the &drm_encoder_helper_funcs.disable,
168 	 * &drm_encoder_helper_funcs.prepare or &drm_encoder_helper_funcs.dpms
169 	 * hook.
170 	 *
171 	 * The bridge can assume that the display pipe (i.e. clocks and timing
172 	 * signals) feeding it is still running when this callback is called.
173 	 *
174 	 * The @disable callback is optional.
175 	 *
176 	 * NOTE:
177 	 *
178 	 * This is deprecated, do not use!
179 	 * New drivers shall use &drm_bridge_funcs.atomic_disable.
180 	 */
181 	void (*disable)(struct drm_bridge *bridge);
182 
183 	/**
184 	 * @post_disable:
185 	 *
186 	 * This callback should disable the bridge. It is called right after the
187 	 * preceding element in the display pipe is disabled. If the preceding
188 	 * element is a bridge this means it's called after that bridge's
189 	 * @post_disable function. If the preceding element is a &drm_encoder
190 	 * it's called right after the encoder's
191 	 * &drm_encoder_helper_funcs.disable, &drm_encoder_helper_funcs.prepare
192 	 * or &drm_encoder_helper_funcs.dpms hook.
193 	 *
194 	 * The bridge must assume that the display pipe (i.e. clocks and timing
195 	 * signals) feeding it is no longer running when this callback is
196 	 * called.
197 	 *
198 	 * The @post_disable callback is optional.
199 	 *
200 	 * NOTE:
201 	 *
202 	 * This is deprecated, do not use!
203 	 * New drivers shall use &drm_bridge_funcs.atomic_post_disable.
204 	 */
205 	void (*post_disable)(struct drm_bridge *bridge);
206 
207 	/**
208 	 * @mode_set:
209 	 *
210 	 * This callback should set the given mode on the bridge. It is called
211 	 * after the @mode_set callback for the preceding element in the display
212 	 * pipeline has been called already. If the bridge is the first element
213 	 * then this would be &drm_encoder_helper_funcs.mode_set. The display
214 	 * pipe (i.e.  clocks and timing signals) is off when this function is
215 	 * called.
216 	 *
217 	 * The adjusted_mode parameter is the mode output by the CRTC for the
218 	 * first bridge in the chain. It can be different from the mode
219 	 * parameter that contains the desired mode for the connector at the end
220 	 * of the bridges chain, for instance when the first bridge in the chain
221 	 * performs scaling. The adjusted mode is mostly useful for the first
222 	 * bridge in the chain and is likely irrelevant for the other bridges.
223 	 *
224 	 * For atomic drivers the adjusted_mode is the mode stored in
225 	 * &drm_crtc_state.adjusted_mode.
226 	 *
227 	 * NOTE:
228 	 *
229 	 * This is deprecated, do not use!
230 	 * New drivers shall set their mode in the
231 	 * &drm_bridge_funcs.atomic_enable operation.
232 	 */
233 	void (*mode_set)(struct drm_bridge *bridge,
234 			 const struct drm_display_mode *mode,
235 			 const struct drm_display_mode *adjusted_mode);
236 	/**
237 	 * @pre_enable:
238 	 *
239 	 * This callback should enable the bridge. It is called right before
240 	 * the preceding element in the display pipe is enabled. If the
241 	 * preceding element is a bridge this means it's called before that
242 	 * bridge's @pre_enable function. If the preceding element is a
243 	 * &drm_encoder it's called right before the encoder's
244 	 * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
245 	 * &drm_encoder_helper_funcs.dpms hook.
246 	 *
247 	 * The display pipe (i.e. clocks and timing signals) feeding this bridge
248 	 * will not yet be running when this callback is called. The bridge must
249 	 * not enable the display link feeding the next bridge in the chain (if
250 	 * there is one) when this callback is called.
251 	 *
252 	 * The @pre_enable callback is optional.
253 	 *
254 	 * NOTE:
255 	 *
256 	 * This is deprecated, do not use!
257 	 * New drivers shall use &drm_bridge_funcs.atomic_pre_enable.
258 	 */
259 	void (*pre_enable)(struct drm_bridge *bridge);
260 
261 	/**
262 	 * @enable:
263 	 *
264 	 * This callback should enable the bridge. It is called right after
265 	 * the preceding element in the display pipe is enabled. If the
266 	 * preceding element is a bridge this means it's called after that
267 	 * bridge's @enable function. If the preceding element is a
268 	 * &drm_encoder it's called right after the encoder's
269 	 * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
270 	 * &drm_encoder_helper_funcs.dpms hook.
271 	 *
272 	 * The bridge can assume that the display pipe (i.e. clocks and timing
273 	 * signals) feeding it is running when this callback is called. This
274 	 * callback must enable the display link feeding the next bridge in the
275 	 * chain if there is one.
276 	 *
277 	 * The @enable callback is optional.
278 	 *
279 	 * NOTE:
280 	 *
281 	 * This is deprecated, do not use!
282 	 * New drivers shall use &drm_bridge_funcs.atomic_enable.
283 	 */
284 	void (*enable)(struct drm_bridge *bridge);
285 
286 	/**
287 	 * @atomic_pre_enable:
288 	 *
289 	 * This callback should enable the bridge. It is called right before
290 	 * the preceding element in the display pipe is enabled. If the
291 	 * preceding element is a bridge this means it's called before that
292 	 * bridge's @atomic_pre_enable or @pre_enable function. If the preceding
293 	 * element is a &drm_encoder it's called right before the encoder's
294 	 * &drm_encoder_helper_funcs.atomic_enable hook.
295 	 *
296 	 * The display pipe (i.e. clocks and timing signals) feeding this bridge
297 	 * will not yet be running when this callback is called. The bridge must
298 	 * not enable the display link feeding the next bridge in the chain (if
299 	 * there is one) when this callback is called.
300 	 *
301 	 * The @atomic_pre_enable callback is optional.
302 	 */
303 	void (*atomic_pre_enable)(struct drm_bridge *bridge,
304 				  struct drm_bridge_state *old_bridge_state);
305 
306 	/**
307 	 * @atomic_enable:
308 	 *
309 	 * This callback should enable the bridge. It is called right after
310 	 * the preceding element in the display pipe is enabled. If the
311 	 * preceding element is a bridge this means it's called after that
312 	 * bridge's @atomic_enable or @enable function. If the preceding element
313 	 * is a &drm_encoder it's called right after the encoder's
314 	 * &drm_encoder_helper_funcs.atomic_enable hook.
315 	 *
316 	 * The bridge can assume that the display pipe (i.e. clocks and timing
317 	 * signals) feeding it is running when this callback is called. This
318 	 * callback must enable the display link feeding the next bridge in the
319 	 * chain if there is one.
320 	 *
321 	 * The @atomic_enable callback is optional.
322 	 */
323 	void (*atomic_enable)(struct drm_bridge *bridge,
324 			      struct drm_bridge_state *old_bridge_state);
325 	/**
326 	 * @atomic_disable:
327 	 *
328 	 * This callback should disable the bridge. It is called right before
329 	 * the preceding element in the display pipe is disabled. If the
330 	 * preceding element is a bridge this means it's called before that
331 	 * bridge's @atomic_disable or @disable vfunc. If the preceding element
332 	 * is a &drm_encoder it's called right before the
333 	 * &drm_encoder_helper_funcs.atomic_disable hook.
334 	 *
335 	 * The bridge can assume that the display pipe (i.e. clocks and timing
336 	 * signals) feeding it is still running when this callback is called.
337 	 *
338 	 * The @atomic_disable callback is optional.
339 	 */
340 	void (*atomic_disable)(struct drm_bridge *bridge,
341 			       struct drm_bridge_state *old_bridge_state);
342 
343 	/**
344 	 * @atomic_post_disable:
345 	 *
346 	 * This callback should disable the bridge. It is called right after the
347 	 * preceding element in the display pipe is disabled. If the preceding
348 	 * element is a bridge this means it's called after that bridge's
349 	 * @atomic_post_disable or @post_disable function. If the preceding
350 	 * element is a &drm_encoder it's called right after the encoder's
351 	 * &drm_encoder_helper_funcs.atomic_disable hook.
352 	 *
353 	 * The bridge must assume that the display pipe (i.e. clocks and timing
354 	 * signals) feeding it is no longer running when this callback is
355 	 * called.
356 	 *
357 	 * The @atomic_post_disable callback is optional.
358 	 */
359 	void (*atomic_post_disable)(struct drm_bridge *bridge,
360 				    struct drm_bridge_state *old_bridge_state);
361 
362 	/**
363 	 * @atomic_duplicate_state:
364 	 *
365 	 * Duplicate the current bridge state object (which is guaranteed to be
366 	 * non-NULL).
367 	 *
368 	 * The atomic_duplicate_state hook is mandatory if the bridge
369 	 * implements any of the atomic hooks, and should be left unassigned
370 	 * otherwise. For bridges that don't subclass &drm_bridge_state, the
371 	 * drm_atomic_helper_bridge_duplicate_state() helper function shall be
372 	 * used to implement this hook.
373 	 *
374 	 * RETURNS:
375 	 * A valid drm_bridge_state object or NULL if the allocation fails.
376 	 */
377 	struct drm_bridge_state *(*atomic_duplicate_state)(struct drm_bridge *bridge);
378 
379 	/**
380 	 * @atomic_destroy_state:
381 	 *
382 	 * Destroy a bridge state object previously allocated by
383 	 * &drm_bridge_funcs.atomic_duplicate_state().
384 	 *
385 	 * The atomic_destroy_state hook is mandatory if the bridge implements
386 	 * any of the atomic hooks, and should be left unassigned otherwise.
387 	 * For bridges that don't subclass &drm_bridge_state, the
388 	 * drm_atomic_helper_bridge_destroy_state() helper function shall be
389 	 * used to implement this hook.
390 	 */
391 	void (*atomic_destroy_state)(struct drm_bridge *bridge,
392 				     struct drm_bridge_state *state);
393 
394 	/**
395 	 * @atomic_get_output_bus_fmts:
396 	 *
397 	 * Return the supported bus formats on the output end of a bridge.
398 	 * The returned array must be allocated with kmalloc() and will be
399 	 * freed by the caller. If the allocation fails, NULL should be
400 	 * returned. num_output_fmts must be set to the returned array size.
401 	 * Formats listed in the returned array should be listed in decreasing
402 	 * preference order (the core will try all formats until it finds one
403 	 * that works).
404 	 *
405 	 * This method is only called on the last element of the bridge chain
406 	 * as part of the bus format negotiation process that happens in
407 	 * &drm_atomic_bridge_chain_select_bus_fmts().
408 	 * This method is optional. When not implemented, the core will
409 	 * fall back to &drm_connector.display_info.bus_formats[0] if
410 	 * &drm_connector.display_info.num_bus_formats > 0,
411 	 * or to MEDIA_BUS_FMT_FIXED otherwise.
412 	 */
413 	u32 *(*atomic_get_output_bus_fmts)(struct drm_bridge *bridge,
414 					   struct drm_bridge_state *bridge_state,
415 					   struct drm_crtc_state *crtc_state,
416 					   struct drm_connector_state *conn_state,
417 					   unsigned int *num_output_fmts);
418 
419 	/**
420 	 * @atomic_get_input_bus_fmts:
421 	 *
422 	 * Return the supported bus formats on the input end of a bridge for
423 	 * a specific output bus format.
424 	 *
425 	 * The returned array must be allocated with kmalloc() and will be
426 	 * freed by the caller. If the allocation fails, NULL should be
427 	 * returned. num_input_fmts must be set to the returned array size.
428 	 * Formats listed in the returned array should be listed in decreasing
429 	 * preference order (the core will try all formats until it finds one
430 	 * that works). When the format is not supported NULL should be
431 	 * returned and num_input_fmts should be set to 0.
432 	 *
433 	 * This method is called on all elements of the bridge chain as part of
434 	 * the bus format negotiation process that happens in
435 	 * drm_atomic_bridge_chain_select_bus_fmts().
436 	 * This method is optional. When not implemented, the core will bypass
437 	 * bus format negotiation on this element of the bridge without
438 	 * failing, and the previous element in the chain will be passed
439 	 * MEDIA_BUS_FMT_FIXED as its output bus format.
440 	 *
441 	 * Bridge drivers that need to support being linked to bridges that are
442 	 * not supporting bus format negotiation should handle the
443 	 * output_fmt == MEDIA_BUS_FMT_FIXED case appropriately, by selecting a
444 	 * sensible default value or extracting this information from somewhere
445 	 * else (FW property, &drm_display_mode, &drm_display_info, ...)
446 	 *
447 	 * Note: Even if input format selection on the first bridge has no
448 	 * impact on the negotiation process (bus format negotiation stops once
449 	 * we reach the first element of the chain), drivers are expected to
450 	 * return accurate input formats as the input format may be used to
451 	 * configure the CRTC output appropriately.
452 	 */
453 	u32 *(*atomic_get_input_bus_fmts)(struct drm_bridge *bridge,
454 					  struct drm_bridge_state *bridge_state,
455 					  struct drm_crtc_state *crtc_state,
456 					  struct drm_connector_state *conn_state,
457 					  u32 output_fmt,
458 					  unsigned int *num_input_fmts);
459 
460 	/**
461 	 * @atomic_check:
462 	 *
463 	 * This method is responsible for checking bridge state correctness.
464 	 * It can also check the state of the surrounding components in chain
465 	 * to make sure the whole pipeline can work properly.
466 	 *
467 	 * &drm_bridge_funcs.atomic_check() hooks are called in reverse
468 	 * order (from the last to the first bridge).
469 	 *
470 	 * This method is optional. &drm_bridge_funcs.mode_fixup() is not
471 	 * called when &drm_bridge_funcs.atomic_check() is implemented, so only
472 	 * one of them should be provided.
473 	 *
474 	 * If drivers need to tweak &drm_bridge_state.input_bus_cfg.flags or
475 	 * &drm_bridge_state.output_bus_cfg.flags it should happen in
476 	 * this function. By default the &drm_bridge_state.output_bus_cfg.flags
477 	 * field is set to the next bridge
478 	 * &drm_bridge_state.input_bus_cfg.flags value or
479 	 * &drm_connector.display_info.bus_flags if the bridge is the last
480 	 * element in the chain.
481 	 *
482 	 * RETURNS:
483 	 * zero if the check passed, a negative error code otherwise.
484 	 */
485 	int (*atomic_check)(struct drm_bridge *bridge,
486 			    struct drm_bridge_state *bridge_state,
487 			    struct drm_crtc_state *crtc_state,
488 			    struct drm_connector_state *conn_state);
489 
490 	/**
491 	 * @atomic_reset:
492 	 *
493 	 * Reset the bridge to a predefined state (or retrieve its current
494 	 * state) and return a &drm_bridge_state object matching this state.
495 	 * This function is called at attach time.
496 	 *
497 	 * The atomic_reset hook is mandatory if the bridge implements any of
498 	 * the atomic hooks, and should be left unassigned otherwise. For
499 	 * bridges that don't subclass &drm_bridge_state, the
500 	 * drm_atomic_helper_bridge_reset() helper function shall be used to
501 	 * implement this hook.
502 	 *
503 	 * Note that the atomic_reset() semantics is not exactly matching the
504 	 * reset() semantics found on other components (connector, plane, ...).
505 	 *
506 	 * 1. The reset operation happens when the bridge is attached, not when
507 	 *    drm_mode_config_reset() is called
508 	 * 2. It's meant to be used exclusively on bridges that have been
509 	 *    converted to the ATOMIC API
510 	 *
511 	 * RETURNS:
512 	 * A valid drm_bridge_state object in case of success, an ERR_PTR()
513 	 * giving the reason of the failure otherwise.
514 	 */
515 	struct drm_bridge_state *(*atomic_reset)(struct drm_bridge *bridge);
516 
517 	/**
518 	 * @detect:
519 	 *
520 	 * Check if anything is attached to the bridge output.
521 	 *
522 	 * This callback is optional, if not implemented the bridge will be
523 	 * considered as always having a component attached to its output.
524 	 * Bridges that implement this callback shall set the
525 	 * DRM_BRIDGE_OP_DETECT flag in their &drm_bridge->ops.
526 	 *
527 	 * RETURNS:
528 	 *
529 	 * drm_connector_status indicating the bridge output status.
530 	 */
531 	enum drm_connector_status (*detect)(struct drm_bridge *bridge);
532 
533 	/**
534 	 * @get_modes:
535 	 *
536 	 * Fill all modes currently valid for the sink into the &drm_connector
537 	 * with drm_mode_probed_add().
538 	 *
539 	 * The @get_modes callback is mostly intended to support non-probeable
540 	 * displays such as many fixed panels. Bridges that support reading
541 	 * EDID shall leave @get_modes unimplemented and implement the
542 	 * &drm_bridge_funcs->get_edid callback instead.
543 	 *
544 	 * This callback is optional. Bridges that implement it shall set the
545 	 * DRM_BRIDGE_OP_MODES flag in their &drm_bridge->ops.
546 	 *
547 	 * The connector parameter shall be used for the sole purpose of
548 	 * filling modes, and shall not be stored internally by bridge drivers
549 	 * for future usage.
550 	 *
551 	 * RETURNS:
552 	 *
553 	 * The number of modes added by calling drm_mode_probed_add().
554 	 */
555 	int (*get_modes)(struct drm_bridge *bridge,
556 			 struct drm_connector *connector);
557 
558 	/**
559 	 * @get_edid:
560 	 *
561 	 * Read and parse the EDID data of the connected display.
562 	 *
563 	 * The @get_edid callback is the preferred way of reporting mode
564 	 * information for a display connected to the bridge output. Bridges
565 	 * that support reading EDID shall implement this callback and leave
566 	 * the @get_modes callback unimplemented.
567 	 *
568 	 * The caller of this operation shall first verify the output
569 	 * connection status and refrain from reading EDID from a disconnected
570 	 * output.
571 	 *
572 	 * This callback is optional. Bridges that implement it shall set the
573 	 * DRM_BRIDGE_OP_EDID flag in their &drm_bridge->ops.
574 	 *
575 	 * The connector parameter shall be used for the sole purpose of EDID
576 	 * retrieval and parsing, and shall not be stored internally by bridge
577 	 * drivers for future usage.
578 	 *
579 	 * RETURNS:
580 	 *
581 	 * An edid structure newly allocated with kmalloc() (or similar) on
582 	 * success, or NULL otherwise. The caller is responsible for freeing
583 	 * the returned edid structure with kfree().
584 	 */
585 	struct edid *(*get_edid)(struct drm_bridge *bridge,
586 				 struct drm_connector *connector);
587 
588 	/**
589 	 * @hpd_notify:
590 	 *
591 	 * Notify the bridge of hot plug detection.
592 	 *
593 	 * This callback is optional, it may be implemented by bridges that
594 	 * need to be notified of display connection or disconnection for
595 	 * internal reasons. One use case is to reset the internal state of CEC
596 	 * controllers for HDMI bridges.
597 	 */
598 	void (*hpd_notify)(struct drm_bridge *bridge,
599 			   enum drm_connector_status status);
600 
601 	/**
602 	 * @hpd_enable:
603 	 *
604 	 * Enable hot plug detection. From now on the bridge shall call
605 	 * drm_bridge_hpd_notify() each time a change is detected in the output
606 	 * connection status, until hot plug detection gets disabled with
607 	 * @hpd_disable.
608 	 *
609 	 * This callback is optional and shall only be implemented by bridges
610 	 * that support hot-plug notification without polling. Bridges that
611 	 * implement it shall also implement the @hpd_disable callback and set
612 	 * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops.
613 	 */
614 	void (*hpd_enable)(struct drm_bridge *bridge);
615 
616 	/**
617 	 * @hpd_disable:
618 	 *
619 	 * Disable hot plug detection. Once this function returns the bridge
620 	 * shall not call drm_bridge_hpd_notify() when a change in the output
621 	 * connection status occurs.
622 	 *
623 	 * This callback is optional and shall only be implemented by bridges
624 	 * that support hot-plug notification without polling. Bridges that
625 	 * implement it shall also implement the @hpd_enable callback and set
626 	 * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops.
627 	 */
628 	void (*hpd_disable)(struct drm_bridge *bridge);
629 
630 	/**
631 	 * @debugfs_init:
632 	 *
633 	 * Allows bridges to create bridge-specific debugfs files.
634 	 */
635 	void (*debugfs_init)(struct drm_bridge *bridge, struct dentry *root);
636 };
637 
638 /**
639  * struct drm_bridge_timings - timing information for the bridge
640  */
641 struct drm_bridge_timings {
642 	/**
643 	 * @input_bus_flags:
644 	 *
645 	 * Tells what additional settings for the pixel data on the bus
646 	 * this bridge requires (like pixel signal polarity). See also
647 	 * &drm_display_info->bus_flags.
648 	 */
649 	u32 input_bus_flags;
650 	/**
651 	 * @setup_time_ps:
652 	 *
653 	 * Defines the time in picoseconds the input data lines must be
654 	 * stable before the clock edge.
655 	 */
656 	u32 setup_time_ps;
657 	/**
658 	 * @hold_time_ps:
659 	 *
660 	 * Defines the time in picoseconds taken for the bridge to sample the
661 	 * input signal after the clock edge.
662 	 */
663 	u32 hold_time_ps;
664 	/**
665 	 * @dual_link:
666 	 *
667 	 * True if the bus operates in dual-link mode. The exact meaning is
668 	 * dependent on the bus type. For LVDS buses, this indicates that even-
669 	 * and odd-numbered pixels are received on separate links.
670 	 */
671 	bool dual_link;
672 };
673 
674 /**
675  * enum drm_bridge_ops - Bitmask of operations supported by the bridge
676  */
677 enum drm_bridge_ops {
678 	/**
679 	 * @DRM_BRIDGE_OP_DETECT: The bridge can detect displays connected to
680 	 * its output. Bridges that set this flag shall implement the
681 	 * &drm_bridge_funcs->detect callback.
682 	 */
683 	DRM_BRIDGE_OP_DETECT = BIT(0),
684 	/**
685 	 * @DRM_BRIDGE_OP_EDID: The bridge can retrieve the EDID of the display
686 	 * connected to its output. Bridges that set this flag shall implement
687 	 * the &drm_bridge_funcs->get_edid callback.
688 	 */
689 	DRM_BRIDGE_OP_EDID = BIT(1),
690 	/**
691 	 * @DRM_BRIDGE_OP_HPD: The bridge can detect hot-plug and hot-unplug
692 	 * without requiring polling. Bridges that set this flag shall
693 	 * implement the &drm_bridge_funcs->hpd_enable and
694 	 * &drm_bridge_funcs->hpd_disable callbacks if they support enabling
695 	 * and disabling hot-plug detection dynamically.
696 	 */
697 	DRM_BRIDGE_OP_HPD = BIT(2),
698 	/**
699 	 * @DRM_BRIDGE_OP_MODES: The bridge can retrieve the modes supported
700 	 * by the display at its output. This does not include reading EDID
701 	 * which is separately covered by @DRM_BRIDGE_OP_EDID. Bridges that set
702 	 * this flag shall implement the &drm_bridge_funcs->get_modes callback.
703 	 */
704 	DRM_BRIDGE_OP_MODES = BIT(3),
705 };
706 
707 /**
708  * struct drm_bridge - central DRM bridge control structure
709  */
710 struct drm_bridge {
711 	/** @base: inherit from &drm_private_object */
712 	struct drm_private_obj base;
713 	/** @dev: DRM device this bridge belongs to */
714 	struct drm_device *dev;
715 	/** @encoder: encoder to which this bridge is connected */
716 	struct drm_encoder *encoder;
717 	/** @chain_node: used to form a bridge chain */
718 	struct list_head chain_node;
719 #ifdef CONFIG_OF
720 	/** @of_node: device node pointer to the bridge */
721 	struct device_node *of_node;
722 #endif
723 	/** @list: to keep track of all added bridges */
724 	struct list_head list;
725 	/**
726 	 * @timings:
727 	 *
728 	 * the timing specification for the bridge, if any (may be NULL)
729 	 */
730 	const struct drm_bridge_timings *timings;
731 	/** @funcs: control functions */
732 	const struct drm_bridge_funcs *funcs;
733 	/** @driver_private: pointer to the bridge driver's internal context */
734 	void *driver_private;
735 	/** @ops: bitmask of operations supported by the bridge */
736 	enum drm_bridge_ops ops;
737 	/**
738 	 * @type: Type of the connection at the bridge output
739 	 * (DRM_MODE_CONNECTOR_*). For bridges at the end of this chain this
740 	 * identifies the type of connected display.
741 	 */
742 	int type;
743 	/**
744 	 * @interlace_allowed: Indicate that the bridge can handle interlaced
745 	 * modes.
746 	 */
747 	bool interlace_allowed;
748 	/**
749 	 * @pre_enable_prev_first: The bridge requires that the prev
750 	 * bridge @pre_enable function is called before its @pre_enable,
751 	 * and conversely for post_disable. This is most frequently a
752 	 * requirement for DSI devices which need the host to be initialised
753 	 * before the peripheral.
754 	 */
755 	bool pre_enable_prev_first;
756 	/**
757 	 * @ddc: Associated I2C adapter for DDC access, if any.
758 	 */
759 	struct i2c_adapter *ddc;
760 	/** private: */
761 	/**
762 	 * @hpd_mutex: Protects the @hpd_cb and @hpd_data fields.
763 	 */
764 	struct mutex hpd_mutex;
765 	/**
766 	 * @hpd_cb: Hot plug detection callback, registered with
767 	 * drm_bridge_hpd_enable().
768 	 */
769 	void (*hpd_cb)(void *data, enum drm_connector_status status);
770 	/**
771 	 * @hpd_data: Private data passed to the Hot plug detection callback
772 	 * @hpd_cb.
773 	 */
774 	void *hpd_data;
775 };
776 
777 static inline struct drm_bridge *
drm_priv_to_bridge(struct drm_private_obj * priv)778 drm_priv_to_bridge(struct drm_private_obj *priv)
779 {
780 	return container_of(priv, struct drm_bridge, base);
781 }
782 
783 void drm_bridge_add(struct drm_bridge *bridge);
784 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge);
785 void drm_bridge_remove(struct drm_bridge *bridge);
786 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
787 		      struct drm_bridge *previous,
788 		      enum drm_bridge_attach_flags flags);
789 
790 #ifdef CONFIG_OF
791 struct drm_bridge *of_drm_find_bridge(struct device_node *np);
792 #else
of_drm_find_bridge(struct device_node * np)793 static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np)
794 {
795 	return NULL;
796 }
797 #endif
798 
799 /**
800  * drm_bridge_get_next_bridge() - Get the next bridge in the chain
801  * @bridge: bridge object
802  *
803  * RETURNS:
804  * the next bridge in the chain after @bridge, or NULL if @bridge is the last.
805  */
806 static inline struct drm_bridge *
drm_bridge_get_next_bridge(struct drm_bridge * bridge)807 drm_bridge_get_next_bridge(struct drm_bridge *bridge)
808 {
809 	if (list_is_last(&bridge->chain_node, &bridge->encoder->bridge_chain))
810 		return NULL;
811 
812 	return list_next_entry(bridge, chain_node);
813 }
814 
815 /**
816  * drm_bridge_get_prev_bridge() - Get the previous bridge in the chain
817  * @bridge: bridge object
818  *
819  * RETURNS:
820  * the previous bridge in the chain, or NULL if @bridge is the first.
821  */
822 static inline struct drm_bridge *
drm_bridge_get_prev_bridge(struct drm_bridge * bridge)823 drm_bridge_get_prev_bridge(struct drm_bridge *bridge)
824 {
825 	if (list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain))
826 		return NULL;
827 
828 	return list_prev_entry(bridge, chain_node);
829 }
830 
831 /**
832  * drm_bridge_chain_get_first_bridge() - Get the first bridge in the chain
833  * @encoder: encoder object
834  *
835  * RETURNS:
836  * the first bridge in the chain, or NULL if @encoder has no bridge attached
837  * to it.
838  */
839 static inline struct drm_bridge *
drm_bridge_chain_get_first_bridge(struct drm_encoder * encoder)840 drm_bridge_chain_get_first_bridge(struct drm_encoder *encoder)
841 {
842 	return list_first_entry_or_null(&encoder->bridge_chain,
843 					struct drm_bridge, chain_node);
844 }
845 
846 /**
847  * drm_for_each_bridge_in_chain() - Iterate over all bridges present in a chain
848  * @encoder: the encoder to iterate bridges on
849  * @bridge: a bridge pointer updated to point to the current bridge at each
850  *	    iteration
851  *
852  * Iterate over all bridges present in the bridge chain attached to @encoder.
853  */
854 #define drm_for_each_bridge_in_chain(encoder, bridge)			\
855 	list_for_each_entry(bridge, &(encoder)->bridge_chain, chain_node)
856 
857 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
858 				 const struct drm_display_mode *mode,
859 				 struct drm_display_mode *adjusted_mode);
860 enum drm_mode_status
861 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
862 			    const struct drm_display_info *info,
863 			    const struct drm_display_mode *mode);
864 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
865 			       const struct drm_display_mode *mode,
866 			       const struct drm_display_mode *adjusted_mode);
867 
868 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
869 				  struct drm_crtc_state *crtc_state,
870 				  struct drm_connector_state *conn_state);
871 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
872 				     struct drm_atomic_state *state);
873 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
874 					  struct drm_atomic_state *state);
875 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
876 					struct drm_atomic_state *state);
877 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
878 				    struct drm_atomic_state *state);
879 
880 u32 *
881 drm_atomic_helper_bridge_propagate_bus_fmt(struct drm_bridge *bridge,
882 					struct drm_bridge_state *bridge_state,
883 					struct drm_crtc_state *crtc_state,
884 					struct drm_connector_state *conn_state,
885 					u32 output_fmt,
886 					unsigned int *num_input_fmts);
887 
888 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge);
889 int drm_bridge_get_modes(struct drm_bridge *bridge,
890 			 struct drm_connector *connector);
891 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
892 				 struct drm_connector *connector);
893 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
894 			   void (*cb)(void *data,
895 				      enum drm_connector_status status),
896 			   void *data);
897 void drm_bridge_hpd_disable(struct drm_bridge *bridge);
898 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
899 			   enum drm_connector_status status);
900 
901 #ifdef CONFIG_DRM_PANEL_BRIDGE
902 bool drm_bridge_is_panel(const struct drm_bridge *bridge);
903 struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel);
904 struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel,
905 					      u32 connector_type);
906 void drm_panel_bridge_remove(struct drm_bridge *bridge);
907 int drm_panel_bridge_set_orientation(struct drm_connector *connector,
908 				     struct drm_bridge *bridge);
909 struct drm_bridge *devm_drm_panel_bridge_add(struct device *dev,
910 					     struct drm_panel *panel);
911 struct drm_bridge *devm_drm_panel_bridge_add_typed(struct device *dev,
912 						   struct drm_panel *panel,
913 						   u32 connector_type);
914 struct drm_bridge *drmm_panel_bridge_add(struct drm_device *drm,
915 					     struct drm_panel *panel);
916 struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge);
917 #else
drm_bridge_is_panel(const struct drm_bridge * bridge)918 static inline bool drm_bridge_is_panel(const struct drm_bridge *bridge)
919 {
920 	return false;
921 }
922 
drm_panel_bridge_set_orientation(struct drm_connector * connector,struct drm_bridge * bridge)923 static inline int drm_panel_bridge_set_orientation(struct drm_connector *connector,
924 						   struct drm_bridge *bridge)
925 {
926 	return -EINVAL;
927 }
928 #endif
929 
930 #if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL_BRIDGE)
931 struct drm_bridge *devm_drm_of_get_bridge(struct device *dev, struct device_node *node,
932 					  u32 port, u32 endpoint);
933 struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm, struct device_node *node,
934 					  u32 port, u32 endpoint);
935 #else
devm_drm_of_get_bridge(struct device * dev,struct device_node * node,u32 port,u32 endpoint)936 static inline struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
937 							struct device_node *node,
938 							u32 port,
939 							u32 endpoint)
940 {
941 	return ERR_PTR(-ENODEV);
942 }
943 
drmm_of_get_bridge(struct drm_device * drm,struct device_node * node,u32 port,u32 endpoint)944 static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
945 						     struct device_node *node,
946 						     u32 port,
947 						     u32 endpoint)
948 {
949 	return ERR_PTR(-ENODEV);
950 }
951 #endif
952 
953 void drm_bridge_debugfs_init(struct drm_minor *minor);
954 
955 #endif
956