1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
|
/*
* Media device
*
* Copyright (C) 2010 Nokia Corporation
*
* Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
* Sakari Ailus <sakari.ailus@iki.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _MEDIA_DEVICE_H
#define _MEDIA_DEVICE_H
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <media/media-devnode.h>
#include <media/media-entity.h>
/**
* DOC: Media Controller
*
* The media controller userspace API is documented in DocBook format in
* Documentation/DocBook/media/v4l/media-controller.xml. This document focus
* on the kernel-side implementation of the media framework.
*
* * Abstract media device model:
*
* Discovering a device internal topology, and configuring it at runtime, is one
* of the goals of the media framework. To achieve this, hardware devices are
* modelled as an oriented graph of building blocks called entities connected
* through pads.
*
* An entity is a basic media hardware building block. It can correspond to
* a large variety of logical blocks such as physical hardware devices
* (CMOS sensor for instance), logical hardware devices (a building block
* in a System-on-Chip image processing pipeline), DMA channels or physical
* connectors.
*
* A pad is a connection endpoint through which an entity can interact with
* other entities. Data (not restricted to video) produced by an entity
* flows from the entity's output to one or more entity inputs. Pads should
* not be confused with physical pins at chip boundaries.
*
* A link is a point-to-point oriented connection between two pads, either
* on the same entity or on different entities. Data flows from a source
* pad to a sink pad.
*
*
* * Media device:
*
* A media device is represented by a struct &media_device instance, defined in
* include/media/media-device.h. Allocation of the structure is handled by the
* media device driver, usually by embedding the &media_device instance in a
* larger driver-specific structure.
*
* Drivers register media device instances by calling
* __media_device_register() via the macro media_device_register()
* and unregistered by calling
* media_device_unregister().
*
* * Entities, pads and links:
*
* - Entities
*
* Entities are represented by a struct &media_entity instance, defined in
* include/media/media-entity.h. The structure is usually embedded into a
* higher-level structure, such as a v4l2_subdev or video_device instance,
* although drivers can allocate entities directly.
*
* Drivers initialize entity pads by calling
* media_entity_pads_init().
*
* Drivers register entities with a media device by calling
* media_device_register_entity()
* and unregistred by calling
* media_device_unregister_entity().
*
* - Interfaces
*
* Interfaces are represented by a struct &media_interface instance, defined in
* include/media/media-entity.h. Currently, only one type of interface is
* defined: a device node. Such interfaces are represented by a struct
* &media_intf_devnode.
*
* Drivers initialize and create device node interfaces by calling
* media_devnode_create()
* and remove them by calling:
* media_devnode_remove().
*
* - Pads
*
* Pads are represented by a struct &media_pad instance, defined in
* include/media/media-entity.h. Each entity stores its pads in a pads array
* managed by the entity driver. Drivers usually embed the array in a
* driver-specific structure.
*
* Pads are identified by their entity and their 0-based index in the pads
* array.
* Both information are stored in the &media_pad structure, making the
* &media_pad pointer the canonical way to store and pass link references.
*
* Pads have flags that describe the pad capabilities and state.
*
* %MEDIA_PAD_FL_SINK indicates that the pad supports sinking data.
* %MEDIA_PAD_FL_SOURCE indicates that the pad supports sourcing data.
*
* NOTE: One and only one of %MEDIA_PAD_FL_SINK and %MEDIA_PAD_FL_SOURCE must
* be set for each pad.
*
* - Links
*
* Links are represented by a struct &media_link instance, defined in
* include/media/media-entity.h. There are two types of links:
*
* 1. pad to pad links:
*
* Associate two entities via their PADs. Each entity has a list that points
* to all links originating at or targeting any of its pads.
* A given link is thus stored twice, once in the source entity and once in
* the target entity.
*
* Drivers create pad to pad links by calling:
* media_create_pad_link() and remove with media_entity_remove_links().
*
* 2. interface to entity links:
*
* Associate one interface to a Link.
*
* Drivers create interface to entity links by calling:
* media_create_intf_link() and remove with media_remove_intf_links().
*
* NOTE:
*
* Links can only be created after having both ends already created.
*
* Links have flags that describe the link capabilities and state. The
* valid values are described at media_create_pad_link() and
* media_create_intf_link().
*
* Graph traversal:
*
* The media framework provides APIs to iterate over entities in a graph.
*
* To iterate over all entities belonging to a media device, drivers can use
* the media_device_for_each_entity macro, defined in
* include/media/media-device.h.
*
* struct media_entity *entity;
*
* media_device_for_each_entity(entity, mdev) {
* // entity will point to each entity in turn
* ...
* }
*
* Drivers might also need to iterate over all entities in a graph that can be
* reached only through enabled links starting at a given entity. The media
* framework provides a depth-first graph traversal API for that purpose.
*
* Note that graphs with cycles (whether directed or undirected) are *NOT*
* supported by the graph traversal API. To prevent infinite loops, the graph
* traversal code limits the maximum depth to MEDIA_ENTITY_ENUM_MAX_DEPTH,
* currently defined as 16.
*
* Drivers initiate a graph traversal by calling
* media_entity_graph_walk_start()
*
* The graph structure, provided by the caller, is initialized to start graph
* traversal at the given entity.
*
* Drivers can then retrieve the next entity by calling
* media_entity_graph_walk_next()
*
* When the graph traversal is complete the function will return NULL.
*
* Graph traversal can be interrupted at any moment. No cleanup function call
* is required and the graph structure can be freed normally.
*
* Helper functions can be used to find a link between two given pads, or a pad
* connected to another pad through an enabled link
* media_entity_find_link() and media_entity_remote_pad()
*
* Use count and power handling:
*
* Due to the wide differences between drivers regarding power management
* needs, the media controller does not implement power management. However,
* the &media_entity structure includes a use_count field that media drivers
* can use to track the number of users of every entity for power management
* needs.
*
* The &media_entity.@use_count field is owned by media drivers and must not be
* touched by entity drivers. Access to the field must be protected by the
* &media_device.@graph_mutex lock.
*
* Links setup:
*
* Link properties can be modified at runtime by calling
* media_entity_setup_link()
*
* Pipelines and media streams:
*
* When starting streaming, drivers must notify all entities in the pipeline to
* prevent link states from being modified during streaming by calling
* media_entity_pipeline_start().
*
* The function will mark all entities connected to the given entity through
* enabled links, either directly or indirectly, as streaming.
*
* The &media_pipeline instance pointed to by the pipe argument will be stored
* in every entity in the pipeline. Drivers should embed the &media_pipeline
* structure in higher-level pipeline structures and can then access the
* pipeline through the &media_entity pipe field.
*
* Calls to media_entity_pipeline_start() can be nested. The pipeline pointer
* must be identical for all nested calls to the function.
*
* media_entity_pipeline_start() may return an error. In that case, it will
* clean up any of the changes it did by itself.
*
* When stopping the stream, drivers must notify the entities with
* media_entity_pipeline_stop().
*
* If multiple calls to media_entity_pipeline_start() have been made the same
* number of media_entity_pipeline_stop() calls are required to stop streaming.
* The &media_entity pipe field is reset to NULL on the last nested stop call.
*
* Link configuration will fail with -%EBUSY by default if either end of the
* link is a streaming entity. Links that can be modified while streaming must
* be marked with the %MEDIA_LNK_FL_DYNAMIC flag.
*
* If other operations need to be disallowed on streaming entities (such as
* changing entities configuration parameters) drivers can explicitly check the
* media_entity stream_count field to find out if an entity is streaming. This
* operation must be done with the media_device graph_mutex held.
*
* Link validation:
*
* Link validation is performed by media_entity_pipeline_start() for any
* entity which has sink pads in the pipeline. The
* &media_entity.@link_validate() callback is used for that purpose. In
* @link_validate() callback, entity driver should check that the properties of
* the source pad of the connected entity and its own sink pad match. It is up
* to the type of the entity (and in the end, the properties of the hardware)
* what matching actually means.
*
* Subsystems should facilitate link validation by providing subsystem specific
* helper functions to provide easy access for commonly needed information, and
* in the end provide a way to use driver-specific callbacks.
*/
struct ida;
struct device;
/**
* struct media_entity_notify - Media Entity Notify
*
* @list: List head
* @notify_data: Input data to invoke the callback
* @notify: Callback function pointer
*
* Drivers may register a callback to take action when
* new entities get registered with the media device.
*/
struct media_entity_notify {
struct list_head list;
void *notify_data;
void (*notify)(struct media_entity *entity, void *notify_data);
};
/**
* struct media_device - Media device
* @dev: Parent device
* @devnode: Media device node
* @driver_name: Optional device driver name. If not set, calls to
* %MEDIA_IOC_DEVICE_INFO will return dev->driver->name.
* This is needed for USB drivers for example, as otherwise
* they'll all appear as if the driver name was "usb".
* @model: Device model name
* @serial: Device serial number (optional)
* @bus_info: Unique and stable device location identifier
* @hw_revision: Hardware device revision
* @driver_version: Device driver version
* @topology_version: Monotonic counter for storing the version of the graph
* topology. Should be incremented each time the topology changes.
* @id: Unique ID used on the last registered graph object
* @entity_internal_idx: Unique internal entity ID used by the graph traversal
* algorithms
* @entity_internal_idx_max: Allocated internal entity indices
* @entities: List of registered entities
* @interfaces: List of registered interfaces
* @pads: List of registered pads
* @links: List of registered links
* @entity_notify: List of registered entity_notify callbacks
* @lock: Entities list lock
* @graph_mutex: Entities graph operation lock
* @pm_count_walk: Graph walk for power state walk. Access serialised using
* graph_mutex.
*
* @source_priv: Driver Private data for enable/disable source handlers
* @enable_source: Enable Source Handler function pointer
* @disable_source: Disable Source Handler function pointer
*
* @link_notify: Link state change notification callback
*
* This structure represents an abstract high-level media device. It allows easy
* access to entities and provides basic media device-level support. The
* structure can be allocated directly or embedded in a larger structure.
*
* The parent @dev is a physical device. It must be set before registering the
* media device.
*
* @model is a descriptive model name exported through sysfs. It doesn't have to
* be unique.
*
* @enable_source is a handler to find source entity for the
* sink entity and activate the link between them if source
* entity is free. Drivers should call this handler before
* accessing the source.
*
* @disable_source is a handler to find source entity for the
* sink entity and deactivate the link between them. Drivers
* should call this handler to release the source.
*
* Note: Bridge driver is expected to implement and set the
* handler when media_device is registered or when
* bridge driver finds the media_device during probe.
* Bridge driver sets source_priv with information
* necessary to run enable/disable source handlers.
*
* Use-case: find tuner entity connected to the decoder
* entity and check if it is available, and activate the
* the link between them from enable_source and deactivate
* from disable_source.
*/
struct media_device {
/* dev->driver_data points to this struct. */
struct device *dev;
struct media_devnode devnode;
char model[32];
char driver_name[32];
char serial[40];
char bus_info[32];
u32 hw_revision;
u32 driver_version;
u32 topology_version;
u32 id;
struct ida entity_internal_idx;
int entity_internal_idx_max;
struct list_head entities;
struct list_head interfaces;
struct list_head pads;
struct list_head links;
/* notify callback list invoked when a new entity is registered */
struct list_head entity_notify;
/* Protects the graph objects creation/removal */
spinlock_t lock;
/* Serializes graph operations. */
struct mutex graph_mutex;
struct media_entity_graph pm_count_walk;
void *source_priv;
int (*enable_source)(struct media_entity *entity,
struct media_pipeline *pipe);
void (*disable_source)(struct media_entity *entity);
int (*link_notify)(struct media_link *link, u32 flags,
unsigned int notification);
};
/* We don't need to include pci.h or usb.h here */
struct pci_dev;
struct usb_device;
#ifdef CONFIG_MEDIA_CONTROLLER
/* Supported link_notify @notification values. */
#define MEDIA_DEV_NOTIFY_PRE_LINK_CH 0
#define MEDIA_DEV_NOTIFY_POST_LINK_CH 1
/* media_devnode to media_device */
#define to_media_device(node) container_of(node, struct media_device, devnode)
/**
* media_entity_enum_init - Initialise an entity enumeration
*
* @ent_enum: Entity enumeration to be initialised
* @mdev: The related media device
*
* Returns zero on success or a negative error code.
*/
static inline __must_check int media_entity_enum_init(
struct media_entity_enum *ent_enum, struct media_device *mdev)
{
return __media_entity_enum_init(ent_enum,
mdev->entity_internal_idx_max + 1);
}
/**
* media_device_init() - Initializes a media device element
*
* @mdev: pointer to struct &media_device
*
* This function initializes the media device prior to its registration.
* The media device initialization and registration is split in two functions
* to avoid race conditions and make the media device available to user-space
* before the media graph has been completed.
*
* So drivers need to first initialize the media device, register any entity
* within the media device, create pad to pad links and then finally register
* the media device by calling media_device_register() as a final step.
*/
void media_device_init(struct media_device *mdev);
/**
* media_device_cleanup() - Cleanups a media device element
|