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TOMOYO Linux Cross Reference
Linux/include/media/media-entity.h

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  1 /*
  2  * Media entity
  3  *
  4  * Copyright (C) 2010 Nokia Corporation
  5  *
  6  * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
  7  *           Sakari Ailus <sakari.ailus@iki.fi>
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License version 2 as
 11  * published by the Free Software Foundation.
 12  *
 13  * This program is distributed in the hope that it will be useful,
 14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16  * GNU General Public License for more details.
 17  *
 18  * You should have received a copy of the GNU General Public License
 19  * along with this program; if not, write to the Free Software
 20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 21  */
 22 
 23 #ifndef _MEDIA_ENTITY_H
 24 #define _MEDIA_ENTITY_H
 25 
 26 #include <linux/bitmap.h>
 27 #include <linux/bug.h>
 28 #include <linux/kernel.h>
 29 #include <linux/list.h>
 30 #include <linux/media.h>
 31 
 32 /* Enums used internally at the media controller to represent graphs */
 33 
 34 /**
 35  * enum media_gobj_type - type of a graph object
 36  *
 37  * @MEDIA_GRAPH_ENTITY:         Identify a media entity
 38  * @MEDIA_GRAPH_PAD:            Identify a media pad
 39  * @MEDIA_GRAPH_LINK:           Identify a media link
 40  * @MEDIA_GRAPH_INTF_DEVNODE:   Identify a media Kernel API interface via
 41  *                              a device node
 42  */
 43 enum media_gobj_type {
 44         MEDIA_GRAPH_ENTITY,
 45         MEDIA_GRAPH_PAD,
 46         MEDIA_GRAPH_LINK,
 47         MEDIA_GRAPH_INTF_DEVNODE,
 48 };
 49 
 50 #define MEDIA_BITS_PER_TYPE             8
 51 #define MEDIA_BITS_PER_ID               (32 - MEDIA_BITS_PER_TYPE)
 52 #define MEDIA_ID_MASK                    GENMASK_ULL(MEDIA_BITS_PER_ID - 1, 0)
 53 
 54 /* Structs to represent the objects that belong to a media graph */
 55 
 56 /**
 57  * struct media_gobj - Define a graph object.
 58  *
 59  * @mdev:       Pointer to the struct media_device that owns the object
 60  * @id:         Non-zero object ID identifier. The ID should be unique
 61  *              inside a media_device, as it is composed by
 62  *              %MEDIA_BITS_PER_TYPE to store the type plus
 63  *              %MEDIA_BITS_PER_ID to store the ID
 64  * @list:       List entry stored in one of the per-type mdev object lists
 65  *
 66  * All objects on the media graph should have this struct embedded
 67  */
 68 struct media_gobj {
 69         struct media_device     *mdev;
 70         u32                     id;
 71         struct list_head        list;
 72 };
 73 
 74 #define MEDIA_ENTITY_ENUM_MAX_DEPTH     16
 75 
 76 /**
 77  * struct media_entity_enum - An enumeration of media entities.
 78  *
 79  * @bmap:       Bit map in which each bit represents one entity at struct
 80  *              media_entity->internal_idx.
 81  * @idx_max:    Number of bits in bmap
 82  */
 83 struct media_entity_enum {
 84         unsigned long *bmap;
 85         int idx_max;
 86 };
 87 
 88 /**
 89  * struct media_entity_graph - Media graph traversal state
 90  *
 91  * @stack:              Graph traversal stack; the stack contains information
 92  *                      on the path the media entities to be walked and the
 93  *                      links through which they were reached.
 94  * @ent_enum:           Visited entities
 95  * @top:                The top of the stack
 96  */
 97 struct media_entity_graph {
 98         struct {
 99                 struct media_entity *entity;
100                 struct list_head *link;
101         } stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];
102 
103         struct media_entity_enum ent_enum;
104         int top;
105 };
106 
107 /*
108  * struct media_pipeline - Media pipeline related information
109  *
110  * @streaming_count:    Streaming start count - streaming stop count
111  * @graph:              Media graph walk during pipeline start / stop
112  */
113 struct media_pipeline {
114         int streaming_count;
115         struct media_entity_graph graph;
116 };
117 
118 /**
119  * struct media_link - A link object part of a media graph.
120  *
121  * @graph_obj:  Embedded structure containing the media object common data
122  * @list:       Linked list associated with an entity or an interface that
123  *              owns the link.
124  * @gobj0:      Part of a union. Used to get the pointer for the first
125  *              graph_object of the link.
126  * @source:     Part of a union. Used only if the first object (gobj0) is
127  *              a pad. In that case, it represents the source pad.
128  * @intf:       Part of a union. Used only if the first object (gobj0) is
129  *              an interface.
130  * @gobj1:      Part of a union. Used to get the pointer for the second
131  *              graph_object of the link.
132  * @source:     Part of a union. Used only if the second object (gobj1) is
133  *              a pad. In that case, it represents the sink pad.
134  * @entity:     Part of a union. Used only if the second object (gobj1) is
135  *              an entity.
136  * @reverse:    Pointer to the link for the reverse direction of a pad to pad
137  *              link.
138  * @flags:      Link flags, as defined in uapi/media.h (MEDIA_LNK_FL_*)
139  * @is_backlink: Indicate if the link is a backlink.
140  */
141 struct media_link {
142         struct media_gobj graph_obj;
143         struct list_head list;
144         union {
145                 struct media_gobj *gobj0;
146                 struct media_pad *source;
147                 struct media_interface *intf;
148         };
149         union {
150                 struct media_gobj *gobj1;
151                 struct media_pad *sink;
152                 struct media_entity *entity;
153         };
154         struct media_link *reverse;
155         unsigned long flags;
156         bool is_backlink;
157 };
158 
159 /**
160  * struct media_pad - A media pad graph object.
161  *
162  * @graph_obj:  Embedded structure containing the media object common data
163  * @entity:     Entity this pad belongs to
164  * @index:      Pad index in the entity pads array, numbered from 0 to n
165  * @flags:      Pad flags, as defined in uapi/media.h (MEDIA_PAD_FL_*)
166  */
167 struct media_pad {
168         struct media_gobj graph_obj;    /* must be first field in struct */
169         struct media_entity *entity;
170         u16 index;
171         unsigned long flags;
172 };
173 
174 /**
175  * struct media_entity_operations - Media entity operations
176  * @link_setup:         Notify the entity of link changes. The operation can
177  *                      return an error, in which case link setup will be
178  *                      cancelled. Optional.
179  * @link_validate:      Return whether a link is valid from the entity point of
180  *                      view. The media_entity_pipeline_start() function
181  *                      validates all links by calling this operation. Optional.
182  *
183  * Note: Those these callbacks are called with struct media_device.@graph_mutex
184  * mutex held.
185  */
186 struct media_entity_operations {
187         int (*link_setup)(struct media_entity *entity,
188                           const struct media_pad *local,
189                           const struct media_pad *remote, u32 flags);
190         int (*link_validate)(struct media_link *link);
191 };
192 
193 /**
194  * enum media_entity_type - Media entity type
195  *
196  * @MEDIA_ENTITY_TYPE_BASE:
197  *      The entity isn't embedded in another subsystem structure.
198  * @MEDIA_ENTITY_TYPE_VIDEO_DEVICE:
199  *      The entity is embedded in a struct video_device instance.
200  * @MEDIA_ENTITY_TYPE_V4L2_SUBDEV:
201  *      The entity is embedded in a struct v4l2_subdev instance.
202  *
203  * Media entity objects are often not instantiated directly, but the media
204  * entity structure is inherited by (through embedding) other subsystem-specific
205  * structures. The media entity type identifies the type of the subclass
206  * structure that implements a media entity instance.
207  *
208  * This allows runtime type identification of media entities and safe casting to
209  * the correct object type. For instance, a media entity structure instance
210  * embedded in a v4l2_subdev structure instance will have the type
211  * MEDIA_ENTITY_TYPE_V4L2_SUBDEV and can safely be cast to a v4l2_subdev
212  * structure using the container_of() macro.
213  */
214 enum media_entity_type {
215         MEDIA_ENTITY_TYPE_BASE,
216         MEDIA_ENTITY_TYPE_VIDEO_DEVICE,
217         MEDIA_ENTITY_TYPE_V4L2_SUBDEV,
218 };
219 
220 /**
221  * struct media_entity - A media entity graph object.
222  *
223  * @graph_obj:  Embedded structure containing the media object common data.
224  * @name:       Entity name.
225  * @obj_type:   Type of the object that implements the media_entity.
226  * @function:   Entity main function, as defined in uapi/media.h
227  *              (MEDIA_ENT_F_*)
228  * @flags:      Entity flags, as defined in uapi/media.h (MEDIA_ENT_FL_*)
229  * @num_pads:   Number of sink and source pads.
230  * @num_links:  Total number of links, forward and back, enabled and disabled.
231  * @num_backlinks: Number of backlinks
232  * @internal_idx: An unique internal entity specific number. The numbers are
233  *              re-used if entities are unregistered or registered again.
234  * @pads:       Pads array with the size defined by @num_pads.
235  * @links:      List of data links.
236  * @ops:        Entity operations.
237  * @stream_count: Stream count for the entity.
238  * @use_count:  Use count for the entity.
239  * @pipe:       Pipeline this entity belongs to.
240  * @info:       Union with devnode information.  Kept just for backward
241  *              compatibility.
242  * @major:      Devnode major number (zero if not applicable). Kept just
243  *              for backward compatibility.
244  * @minor:      Devnode minor number (zero if not applicable). Kept just
245  *              for backward compatibility.
246  *
247  * NOTE: @stream_count and @use_count reference counts must never be
248  * negative, but are signed integers on purpose: a simple WARN_ON(<0) check
249  * can be used to detect reference count bugs that would make them negative.
250  */
251 struct media_entity {
252         struct media_gobj graph_obj;    /* must be first field in struct */
253         const char *name;
254         enum media_entity_type obj_type;
255         u32 function;
256         unsigned long flags;
257 
258         u16 num_pads;
259         u16 num_links;
260         u16 num_backlinks;
261         int internal_idx;
262 
263         struct media_pad *pads;
264         struct list_head links;
265 
266         const struct media_entity_operations *ops;
267 
268         /* Reference counts must never be negative, but are signed integers on
269          * purpose: a simple WARN_ON(<0) check can be used to detect reference
270          * count bugs that would make them negative.
271          */
272         int stream_count;
273         int use_count;
274 
275         struct media_pipeline *pipe;
276 
277         union {
278                 struct {
279                         u32 major;
280                         u32 minor;
281                 } dev;
282         } info;
283 };
284 
285 /**
286  * struct media_interface - A media interface graph object.
287  *
288  * @graph_obj:          embedded graph object
289  * @links:              List of links pointing to graph entities
290  * @type:               Type of the interface as defined in the
291  *                      uapi/media/media.h header, e. g.
292  *                      MEDIA_INTF_T_*
293  * @flags:              Interface flags as defined in uapi/media/media.h
294  */
295 struct media_interface {
296         struct media_gobj               graph_obj;
297         struct list_head                links;
298         u32                             type;
299         u32                             flags;
300 };
301 
302 /**
303  * struct media_intf_devnode - A media interface via a device node.
304  *
305  * @intf:       embedded interface object
306  * @major:      Major number of a device node
307  * @minor:      Minor number of a device node
308  */
309 struct media_intf_devnode {
310         struct media_interface          intf;
311 
312         /* Should match the fields at media_v2_intf_devnode */
313         u32                             major;
314         u32                             minor;
315 };
316 
317 /**
318  * media_entity_id() - return the media entity graph object id
319  *
320  * @entity:     pointer to entity
321  */
322 static inline u32 media_entity_id(struct media_entity *entity)
323 {
324         return entity->graph_obj.id;
325 }
326 
327 /**
328  * media_type() - return the media object type
329  *
330  * @gobj:       pointer to the media graph object
331  */
332 static inline enum media_gobj_type media_type(struct media_gobj *gobj)
333 {
334         return gobj->id >> MEDIA_BITS_PER_ID;
335 }
336 
337 /**
338  * media_id() - return the media object ID
339  *
340  * @gobj:       pointer to the media graph object
341  */
342 static inline u32 media_id(struct media_gobj *gobj)
343 {
344         return gobj->id & MEDIA_ID_MASK;
345 }
346 
347 /**
348  * media_gobj_gen_id() - encapsulates type and ID on at the object ID
349  *
350  * @type:       object type as define at enum &media_gobj_type.
351  * @local_id:   next ID, from struct &media_device.@id.
352  */
353 static inline u32 media_gobj_gen_id(enum media_gobj_type type, u64 local_id)
354 {
355         u32 id;
356 
357         id = type << MEDIA_BITS_PER_ID;
358         id |= local_id & MEDIA_ID_MASK;
359 
360         return id;
361 }
362 
363 /**
364  * is_media_entity_v4l2_video_device() - Check if the entity is a video_device
365  * @entity:     pointer to entity
366  *
367  * Return: true if the entity is an instance of a video_device object and can
368  * safely be cast to a struct video_device using the container_of() macro, or
369  * false otherwise.
370  */
371 static inline bool is_media_entity_v4l2_video_device(struct media_entity *entity)
372 {
373         return entity && entity->obj_type == MEDIA_ENTITY_TYPE_VIDEO_DEVICE;
374 }
375 
376 /**
377  * is_media_entity_v4l2_subdev() - Check if the entity is a v4l2_subdev
378  * @entity:     pointer to entity
379  *
380  * Return: true if the entity is an instance of a v4l2_subdev object and can
381  * safely be cast to a struct v4l2_subdev using the container_of() macro, or
382  * false otherwise.
383  */
384 static inline bool is_media_entity_v4l2_subdev(struct media_entity *entity)
385 {
386         return entity && entity->obj_type == MEDIA_ENTITY_TYPE_V4L2_SUBDEV;
387 }
388 
389 /**
390  * __media_entity_enum_init - Initialise an entity enumeration
391  *
392  * @ent_enum: Entity enumeration to be initialised
393  * @idx_max: Maximum number of entities in the enumeration
394  *
395  * Return: Returns zero on success or a negative error code.
396  */
397 __must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
398                                           int idx_max);
399 
400 /**
401  * media_entity_enum_cleanup - Release resources of an entity enumeration
402  *
403  * @ent_enum: Entity enumeration to be released
404  */
405 void media_entity_enum_cleanup(struct media_entity_enum *ent_enum);
406 
407 /**
408  * media_entity_enum_zero - Clear the entire enum
409  *
410  * @ent_enum: Entity enumeration to be cleared
411  */
412 static inline void media_entity_enum_zero(struct media_entity_enum *ent_enum)
413 {
414         bitmap_zero(ent_enum->bmap, ent_enum->idx_max);
415 }
416 
417 /**
418  * media_entity_enum_set - Mark a single entity in the enum
419  *
420  * @ent_enum: Entity enumeration
421  * @entity: Entity to be marked
422  */
423 static inline void media_entity_enum_set(struct media_entity_enum *ent_enum,
424                                          struct media_entity *entity)
425 {
426         if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
427                 return;
428 
429         __set_bit(entity->internal_idx, ent_enum->bmap);
430 }
431 
432 /**
433  * media_entity_enum_clear - Unmark a single entity in the enum
434  *
435  * @ent_enum: Entity enumeration
436  * @entity: Entity to be unmarked
437  */
438 static inline void media_entity_enum_clear(struct media_entity_enum *ent_enum,
439                                            struct media_entity *entity)
440 {
441         if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
442                 return;
443 
444         __clear_bit(entity->internal_idx, ent_enum->bmap);
445 }
446 
447 /**
448  * media_entity_enum_test - Test whether the entity is marked
449  *
450  * @ent_enum: Entity enumeration
451  * @entity: Entity to be tested
452  *
453  * Returns true if the entity was marked.
454  */
455 static inline bool media_entity_enum_test(struct media_entity_enum *ent_enum,
456                                           struct media_entity *entity)
457 {
458         if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
459                 return true;
460 
461         return test_bit(entity->internal_idx, ent_enum->bmap);
462 }
463 
464 /**
465  * media_entity_enum_test - Test whether the entity is marked, and mark it
466  *
467  * @ent_enum: Entity enumeration
468  * @entity: Entity to be tested
469  *
470  * Returns true if the entity was marked, and mark it before doing so.
471  */
472 static inline bool
473 media_entity_enum_test_and_set(struct media_entity_enum *ent_enum,
474                                struct media_entity *entity)
475 {
476         if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
477                 return true;
478 
479         return __test_and_set_bit(entity->internal_idx, ent_enum->bmap);
480 }
481 
482 /**
483  * media_entity_enum_empty - Test whether the entire enum is empty
484  *
485  * @ent_enum: Entity enumeration
486  *
487  * Returns true if the entity was marked.
488  */
489 static inline bool media_entity_enum_empty(struct media_entity_enum *ent_enum)
490 {
491         return bitmap_empty(ent_enum->bmap, ent_enum->idx_max);
492 }
493 
494 /**
495  * media_entity_enum_intersects - Test whether two enums intersect
496  *
497  * @ent_enum1: First entity enumeration
498  * @ent_enum2: Second entity enumeration
499  *
500  * Returns true if entity enumerations e and f intersect, otherwise false.
501  */
502 static inline bool media_entity_enum_intersects(
503         struct media_entity_enum *ent_enum1,
504         struct media_entity_enum *ent_enum2)
505 {
506         WARN_ON(ent_enum1->idx_max != ent_enum2->idx_max);
507 
508         return bitmap_intersects(ent_enum1->bmap, ent_enum2->bmap,
509                                  min(ent_enum1->idx_max, ent_enum2->idx_max));
510 }
511 
512 #define gobj_to_entity(gobj) \
513                 container_of(gobj, struct media_entity, graph_obj)
514 
515 #define gobj_to_pad(gobj) \
516                 container_of(gobj, struct media_pad, graph_obj)
517 
518 #define gobj_to_link(gobj) \
519                 container_of(gobj, struct media_link, graph_obj)
520 
521 #define gobj_to_link(gobj) \
522                 container_of(gobj, struct media_link, graph_obj)
523 
524 #define gobj_to_pad(gobj) \
525                 container_of(gobj, struct media_pad, graph_obj)
526 
527 #define gobj_to_intf(gobj) \
528                 container_of(gobj, struct media_interface, graph_obj)
529 
530 #define intf_to_devnode(intf) \
531                 container_of(intf, struct media_intf_devnode, intf)
532 
533 /**
534  *  media_gobj_create - Initialize a graph object
535  *
536  * @mdev:       Pointer to the media_device that contains the object
537  * @type:       Type of the object
538  * @gobj:       Pointer to the graph object
539  *
540  * This routine initializes the embedded struct media_gobj inside a
541  * media graph object. It is called automatically if media_*_create()
542  * calls are used. However, if the object (entity, link, pad, interface)
543  * is embedded on some other object, this function should be called before
544  * registering the object at the media controller.
545  */
546 void media_gobj_create(struct media_device *mdev,
547                     enum media_gobj_type type,
548                     struct media_gobj *gobj);
549 
550 /**
551  *  media_gobj_destroy - Stop using a graph object on a media device
552  *
553  * @gobj:       Pointer to the graph object
554  *
555  * This should be called by all routines like media_device_unregister()
556  * that remove/destroy media graph objects.
557  */
558 void media_gobj_destroy(struct media_gobj *gobj);
559 
560 /**
561  * media_entity_pads_init() - Initialize the entity pads
562  *
563  * @entity:     entity where the pads belong
564  * @num_pads:   total number of sink and source pads
565  * @pads:       Array of @num_pads pads.
566  *
567  * The pads array is managed by the entity driver and passed to
568  * media_entity_pads_init() where its pointer will be stored in the entity
569  * structure.
570  *
571  * If no pads are needed, drivers could either directly fill
572  * &media_entity->@num_pads with 0 and &media_entity->@pads with NULL or call
573  * this function that will do the same.
574  *
575  * As the number of pads is known in advance, the pads array is not allocated
576  * dynamically but is managed by the entity driver. Most drivers will embed the
577  * pads array in a driver-specific structure, avoiding dynamic allocation.
578  *
579  * Drivers must set the direction of every pad in the pads array before calling
580  * media_entity_pads_init(). The function will initialize the other pads fields.
581  */
582 int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
583                       struct media_pad *pads);
584 
585 /**
586  * media_entity_cleanup() - free resources associated with an entity
587  *
588  * @entity:     entity where the pads belong
589  *
590  * This function must be called during the cleanup phase after unregistering
591  * the entity (currently, it does nothing).
592  */
593 static inline void media_entity_cleanup(struct media_entity *entity) {};
594 
595 /**
596  * media_create_pad_link() - creates a link between two entities.
597  *
598  * @source:     pointer to &media_entity of the source pad.
599  * @source_pad: number of the source pad in the pads array
600  * @sink:       pointer to &media_entity of the sink pad.
601  * @sink_pad:   number of the sink pad in the pads array.
602  * @flags:      Link flags, as defined in include/uapi/linux/media.h.
603  *
604  * Valid values for flags:
605  * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
606  *      used to transfer media data. When two or more links target a sink pad,
607  *      only one of them can be enabled at a time.
608  *
609  * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
610  *      be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
611  *      %MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
612  *      always enabled.
613  *
614  * NOTE:
615  *
616  * Before calling this function, media_entity_pads_init() and
617  * media_device_register_entity() should be called previously for both ends.
618  */
619 __must_check int media_create_pad_link(struct media_entity *source,
620                         u16 source_pad, struct media_entity *sink,
621                         u16 sink_pad, u32 flags);
622 
623 /**
624  * media_create_pad_links() - creates a link between two entities.
625  *
626  * @mdev: Pointer to the media_device that contains the object
627  * @source_function: Function of the source entities. Used only if @source is
628  *      NULL.
629  * @source: pointer to &media_entity of the source pad. If NULL, it will use
630  *      all entities that matches the @sink_function.
631  * @source_pad: number of the source pad in the pads array
632  * @sink_function: Function of the sink entities. Used only if @sink is NULL.
633  * @sink: pointer to &media_entity of the sink pad. If NULL, it will use
634  *      all entities that matches the @sink_function.
635  * @sink_pad: number of the sink pad in the pads array.
636  * @flags: Link flags, as defined in include/uapi/linux/media.h.
637  * @allow_both_undefined: if true, then both @source and @sink can be NULL.
638  *      In such case, it will create a crossbar between all entities that
639  *      matches @source_function to all entities that matches @sink_function.
640  *      If false, it will return 0 and won't create any link if both @source
641  *      and @sink are NULL.
642  *
643  * Valid values for flags:
644  * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
645  *      used to transfer media data. If multiple links are created and this
646  *      flag is passed as an argument, only the first created link will have
647  *      this flag.
648  *
649  * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
650  *      be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
651  *      %MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
652  *      always enabled.
653  *
654  * It is common for some devices to have multiple source and/or sink entities
655  * of the same type that should be linked. While media_create_pad_link()
656  * creates link by link, this function is meant to allow 1:n, n:1 and even
657  * cross-bar (n:n) links.
658  *
659  * NOTE: Before calling this function, media_entity_pads_init() and
660  * media_device_register_entity() should be called previously for the entities
661  * to be linked.
662  */
663 int media_create_pad_links(const struct media_device *mdev,
664                            const u32 source_function,
665                            struct media_entity *source,
666                            const u16 source_pad,
667                            const u32 sink_function,
668                            struct media_entity *sink,
669                            const u16 sink_pad,
670                            u32 flags,
671                            const bool allow_both_undefined);
672 
673 void __media_entity_remove_links(struct media_entity *entity);
674 
675 /**
676  * media_entity_remove_links() - remove all links associated with an entity
677  *
678  * @entity:     pointer to &media_entity
679  *
680  * Note: this is called automatically when an entity is unregistered via
681  * media_device_register_entity().
682  */
683 void media_entity_remove_links(struct media_entity *entity);
684 
685 /**
686  * __media_entity_setup_link - Configure a media link without locking
687  * @link: The link being configured
688  * @flags: Link configuration flags
689  *
690  * The bulk of link setup is handled by the two entities connected through the
691  * link. This function notifies both entities of the link configuration change.
692  *
693  * If the link is immutable or if the current and new configuration are
694  * identical, return immediately.
695  *
696  * The user is expected to hold link->source->parent->mutex. If not,
697  * media_entity_setup_link() should be used instead.
698  */
699 int __media_entity_setup_link(struct media_link *link, u32 flags);
700 
701 /**
702  * media_entity_setup_link() - changes the link flags properties in runtime
703  *
704  * @link:       pointer to &media_link
705  * @flags:      the requested new link flags
706  *
707  * The only configurable property is the %MEDIA_LNK_FL_ENABLED link flag
708  * flag to enable/disable a link. Links marked with the
709  * %MEDIA_LNK_FL_IMMUTABLE link flag can not be enabled or disabled.
710  *
711  * When a link is enabled or disabled, the media framework calls the
712  * link_setup operation for the two entities at the source and sink of the
713  * link, in that order. If the second link_setup call fails, another
714  * link_setup call is made on the first entity to restore the original link
715  * flags.
716  *
717  * Media device drivers can be notified of link setup operations by setting the
718  * media_device::link_notify pointer to a callback function. If provided, the
719  * notification callback will be called before enabling and after disabling
720  * links.
721  *
722  * Entity drivers must implement the link_setup operation if any of their links
723  * is non-immutable. The operation must either configure the hardware or store
724  * the configuration information to be applied later.
725  *
726  * Link configuration must not have any side effect on other links. If an
727  * enabled link at a sink pad prevents another link at the same pad from
728  * being enabled, the link_setup operation must return -EBUSY and can't
729  * implicitly disable the first enabled link.
730  *
731  * NOTE: the valid values of the flags for the link is the same as described
732  * on media_create_pad_link(), for pad to pad links or the same as described
733  * on media_create_intf_link(), for interface to entity links.
734  */
735 int media_entity_setup_link(struct media_link *link, u32 flags);
736 
737 /**
738  * media_entity_find_link - Find a link between two pads
739  * @source: Source pad
740  * @sink: Sink pad
741  *
742  * Return a pointer to the link between the two entities. If no such link
743  * exists, return NULL.
744  */
745 struct media_link *media_entity_find_link(struct media_pad *source,
746                 struct media_pad *sink);
747 
748 /**
749  * media_entity_remote_pad - Find the pad at the remote end of a link
750  * @pad: Pad at the local end of the link
751  *
752  * Search for a remote pad connected to the given pad by iterating over all
753  * links originating or terminating at that pad until an enabled link is found.
754  *
755  * Return a pointer to the pad at the remote end of the first found enabled
756  * link, or NULL if no enabled link has been found.
757  */
758 struct media_pad *media_entity_remote_pad(struct media_pad *pad);
759 
760 /**
761  * media_entity_get - Get a reference to the parent module
762  *
763  * @entity: The entity
764  *
765  * Get a reference to the parent media device module.
766  *
767  * The function will return immediately if @entity is NULL.
768  *
769  * Return a pointer to the entity on success or NULL on failure.
770  */
771 struct media_entity *media_entity_get(struct media_entity *entity);
772 
773 __must_check int media_entity_graph_walk_init(
774         struct media_entity_graph *graph, struct media_device *mdev);
775 
776 /**
777  * media_entity_graph_walk_cleanup - Release resources used by graph walk.
778  *
779  * @graph: Media graph structure that will be used to walk the graph
780  */
781 void media_entity_graph_walk_cleanup(struct media_entity_graph *graph);
782 
783 /**
784  * media_entity_put - Release the reference to the parent module
785  *
786  * @entity: The entity
787  *
788  * Release the reference count acquired by media_entity_get().
789  *
790  * The function will return immediately if @entity is NULL.
791  */
792 void media_entity_put(struct media_entity *entity);
793 
794 /**
795  * media_entity_graph_walk_start - Start walking the media graph at a given entity
796  * @graph: Media graph structure that will be used to walk the graph
797  * @entity: Starting entity
798  *
799  * Before using this function, media_entity_graph_walk_init() must be
800  * used to allocate resources used for walking the graph. This
801  * function initializes the graph traversal structure to walk the
802  * entities graph starting at the given entity. The traversal
803  * structure must not be modified by the caller during graph
804  * traversal. After the graph walk, the resources must be released
805  * using media_entity_graph_walk_cleanup().
806  */
807 void media_entity_graph_walk_start(struct media_entity_graph *graph,
808                                    struct media_entity *entity);
809 
810 /**
811  * media_entity_graph_walk_next - Get the next entity in the graph
812  * @graph: Media graph structure
813  *
814  * Perform a depth-first traversal of the given media entities graph.
815  *
816  * The graph structure must have been previously initialized with a call to
817  * media_entity_graph_walk_start().
818  *
819  * Return the next entity in the graph or NULL if the whole graph have been
820  * traversed.
821  */
822 struct media_entity *
823 media_entity_graph_walk_next(struct media_entity_graph *graph);
824 
825 /**
826  * media_entity_pipeline_start - Mark a pipeline as streaming
827  * @entity: Starting entity
828  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
829  *
830  * Mark all entities connected to a given entity through enabled links, either
831  * directly or indirectly, as streaming. The given pipeline object is assigned to
832  * every entity in the pipeline and stored in the media_entity pipe field.
833  *
834  * Calls to this function can be nested, in which case the same number of
835  * media_entity_pipeline_stop() calls will be required to stop streaming. The
836  * pipeline pointer must be identical for all nested calls to
837  * media_entity_pipeline_start().
838  */
839 __must_check int media_entity_pipeline_start(struct media_entity *entity,
840                                              struct media_pipeline *pipe);
841 /**
842  * __media_entity_pipeline_start - Mark a pipeline as streaming
843  *
844  * @entity: Starting entity
845  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
846  *
847  * Note: This is the non-locking version of media_entity_pipeline_start()
848  */
849 __must_check int __media_entity_pipeline_start(struct media_entity *entity,
850                                                struct media_pipeline *pipe);
851 
852 /**
853  * media_entity_pipeline_stop - Mark a pipeline as not streaming
854  * @entity: Starting entity
855  *
856  * Mark all entities connected to a given entity through enabled links, either
857  * directly or indirectly, as not streaming. The media_entity pipe field is
858  * reset to NULL.
859  *
860  * If multiple calls to media_entity_pipeline_start() have been made, the same
861  * number of calls to this function are required to mark the pipeline as not
862  * streaming.
863  */
864 void media_entity_pipeline_stop(struct media_entity *entity);
865 
866 /**
867  * __media_entity_pipeline_stop - Mark a pipeline as not streaming
868  *
869  * @entity: Starting entity
870  *
871  * Note: This is the non-locking version of media_entity_pipeline_stop()
872  */
873 void __media_entity_pipeline_stop(struct media_entity *entity);
874 
875 /**
876  * media_devnode_create() - creates and initializes a device node interface
877  *
878  * @mdev:       pointer to struct &media_device
879  * @type:       type of the interface, as given by MEDIA_INTF_T_* macros
880  *              as defined in the uapi/media/media.h header.
881  * @flags:      Interface flags as defined in uapi/media/media.h.
882  * @major:      Device node major number.
883  * @minor:      Device node minor number.
884  *
885  * Return: if succeeded, returns a pointer to the newly allocated
886  *      &media_intf_devnode pointer.
887  */
888 struct media_intf_devnode *
889 __must_check media_devnode_create(struct media_device *mdev,
890                                   u32 type, u32 flags,
891                                   u32 major, u32 minor);
892 /**
893  * media_devnode_remove() - removes a device node interface
894  *
895  * @devnode:    pointer to &media_intf_devnode to be freed.
896  *
897  * When a device node interface is removed, all links to it are automatically
898  * removed.
899  */
900 void media_devnode_remove(struct media_intf_devnode *devnode);
901 struct media_link *
902 
903 /**
904  * media_create_intf_link() - creates a link between an entity and an interface
905  *
906  * @entity:     pointer to %media_entity
907  * @intf:       pointer to %media_interface
908  * @flags:      Link flags, as defined in include/uapi/linux/media.h.
909  *
910  *
911  * Valid values for flags:
912  * The %MEDIA_LNK_FL_ENABLED flag indicates that the interface is connected to
913  *      the entity hardware. That's the default value for interfaces. An
914  *      interface may be disabled if the hardware is busy due to the usage
915  *      of some other interface that it is currently controlling the hardware.
916  *      A typical example is an hybrid TV device that handle only one type of
917  *      stream on a given time. So, when the digital TV is streaming,
918  *      the V4L2 interfaces won't be enabled, as such device is not able to
919  *      also stream analog TV or radio.
920  *
921  * Note:
922  *
923  * Before calling this function, media_devnode_create() should be called for
924  * the interface and media_device_register_entity() should be called for the
925  * interface that will be part of the link.
926  */
927 __must_check media_create_intf_link(struct media_entity *entity,
928                                     struct media_interface *intf,
929                                     u32 flags);
930 /**
931  * __media_remove_intf_link() - remove a single interface link
932  *
933  * @link:       pointer to &media_link.
934  *
935  * Note: this is an unlocked version of media_remove_intf_link()
936  */
937 void __media_remove_intf_link(struct media_link *link);
938 
939 /**
940  * media_remove_intf_link() - remove a single interface link
941  *
942  * @link:       pointer to &media_link.
943  *
944  * Note: prefer to use this one, instead of __media_remove_intf_link()
945  */
946 void media_remove_intf_link(struct media_link *link);
947 
948 /**
949  * __media_remove_intf_links() - remove all links associated with an interface
950  *
951  * @intf:       pointer to &media_interface
952  *
953  * Note: this is an unlocked version of media_remove_intf_links().
954  */
955 void __media_remove_intf_links(struct media_interface *intf);
956 
957 /**
958  * media_remove_intf_links() - remove all links associated with an interface
959  *
960  * @intf:       pointer to &media_interface
961  *
962  * Notes:
963  *
964  * this is called automatically when an entity is unregistered via
965  * media_device_register_entity() and by media_devnode_remove().
966  *
967  * Prefer to use this one, instead of __media_remove_intf_links().
968  */
969 void media_remove_intf_links(struct media_interface *intf);
970 
971 #define media_entity_call(entity, operation, args...)                   \
972         (((entity)->ops && (entity)->ops->operation) ?                  \
973          (entity)->ops->operation((entity) , ##args) : -ENOIOCTLCMD)
974 
975 #endif
976 

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