[media] media: Links setup
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / media / media-entity.c
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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#include <linux/module.h>
24#include <linux/slab.h>
25#include <media/media-entity.h>
503c3d82 26#include <media/media-device.h>
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27
28/**
29 * media_entity_init - Initialize a media entity
30 *
31 * @num_pads: Total number of sink and source pads.
32 * @extra_links: Initial estimate of the number of extra links.
33 * @pads: Array of 'num_pads' pads.
34 *
35 * The total number of pads is an intrinsic property of entities known by the
36 * entity driver, while the total number of links depends on hardware design
37 * and is an extrinsic property unknown to the entity driver. However, in most
38 * use cases the entity driver can guess the number of links which can safely
39 * be assumed to be equal to or larger than the number of pads.
40 *
41 * For those reasons the links array can be preallocated based on the entity
42 * driver guess and will be reallocated later if extra links need to be
43 * created.
44 *
45 * This function allocates a links array with enough space to hold at least
46 * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
47 * be set to the number of allocated elements.
48 *
49 * The pads array is managed by the entity driver and passed to
50 * media_entity_init() where its pointer will be stored in the entity structure.
51 */
52int
53media_entity_init(struct media_entity *entity, u16 num_pads,
54 struct media_pad *pads, u16 extra_links)
55{
56 struct media_link *links;
57 unsigned int max_links = num_pads + extra_links;
58 unsigned int i;
59
60 links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
61 if (links == NULL)
62 return -ENOMEM;
63
64 entity->group_id = 0;
65 entity->max_links = max_links;
66 entity->num_links = 0;
67 entity->num_backlinks = 0;
68 entity->num_pads = num_pads;
69 entity->pads = pads;
70 entity->links = links;
71
72 for (i = 0; i < num_pads; i++) {
73 pads[i].entity = entity;
74 pads[i].index = i;
75 }
76
77 return 0;
78}
79EXPORT_SYMBOL_GPL(media_entity_init);
80
81void
82media_entity_cleanup(struct media_entity *entity)
83{
84 kfree(entity->links);
85}
86EXPORT_SYMBOL_GPL(media_entity_cleanup);
87
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88/* -----------------------------------------------------------------------------
89 * Graph traversal
90 */
91
92static struct media_entity *
93media_entity_other(struct media_entity *entity, struct media_link *link)
94{
95 if (link->source->entity == entity)
96 return link->sink->entity;
97 else
98 return link->source->entity;
99}
100
101/* push an entity to traversal stack */
102static void stack_push(struct media_entity_graph *graph,
103 struct media_entity *entity)
104{
105 if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
106 WARN_ON(1);
107 return;
108 }
109 graph->top++;
110 graph->stack[graph->top].link = 0;
111 graph->stack[graph->top].entity = entity;
112}
113
114static struct media_entity *stack_pop(struct media_entity_graph *graph)
115{
116 struct media_entity *entity;
117
118 entity = graph->stack[graph->top].entity;
119 graph->top--;
120
121 return entity;
122}
123
124#define stack_peek(en) ((en)->stack[(en)->top - 1].entity)
125#define link_top(en) ((en)->stack[(en)->top].link)
126#define stack_top(en) ((en)->stack[(en)->top].entity)
127
128/**
129 * media_entity_graph_walk_start - Start walking the media graph at a given entity
130 * @graph: Media graph structure that will be used to walk the graph
131 * @entity: Starting entity
132 *
133 * This function initializes the graph traversal structure to walk the entities
134 * graph starting at the given entity. The traversal structure must not be
135 * modified by the caller during graph traversal. When done the structure can
136 * safely be freed.
137 */
138void media_entity_graph_walk_start(struct media_entity_graph *graph,
139 struct media_entity *entity)
140{
141 graph->top = 0;
142 graph->stack[graph->top].entity = NULL;
143 stack_push(graph, entity);
144}
145EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
146
147/**
148 * media_entity_graph_walk_next - Get the next entity in the graph
149 * @graph: Media graph structure
150 *
151 * Perform a depth-first traversal of the given media entities graph.
152 *
153 * The graph structure must have been previously initialized with a call to
154 * media_entity_graph_walk_start().
155 *
156 * Return the next entity in the graph or NULL if the whole graph have been
157 * traversed.
158 */
159struct media_entity *
160media_entity_graph_walk_next(struct media_entity_graph *graph)
161{
162 if (stack_top(graph) == NULL)
163 return NULL;
164
165 /*
166 * Depth first search. Push entity to stack and continue from
167 * top of the stack until no more entities on the level can be
168 * found.
169 */
170 while (link_top(graph) < stack_top(graph)->num_links) {
171 struct media_entity *entity = stack_top(graph);
172 struct media_link *link = &entity->links[link_top(graph)];
173 struct media_entity *next;
174
175 /* The link is not enabled so we do not follow. */
176 if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
177 link_top(graph)++;
178 continue;
179 }
180
181 /* Get the entity in the other end of the link . */
182 next = media_entity_other(entity, link);
183
184 /* Was it the entity we came here from? */
185 if (next == stack_peek(graph)) {
186 link_top(graph)++;
187 continue;
188 }
189
190 /* Push the new entity to stack and start over. */
191 link_top(graph)++;
192 stack_push(graph, next);
193 }
194
195 return stack_pop(graph);
196}
197EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
198
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199/* -----------------------------------------------------------------------------
200 * Module use count
201 */
202
203/*
204 * media_entity_get - Get a reference to the parent module
205 * @entity: The entity
206 *
207 * Get a reference to the parent media device module.
208 *
209 * The function will return immediately if @entity is NULL.
210 *
211 * Return a pointer to the entity on success or NULL on failure.
212 */
213struct media_entity *media_entity_get(struct media_entity *entity)
214{
215 if (entity == NULL)
216 return NULL;
217
218 if (entity->parent->dev &&
219 !try_module_get(entity->parent->dev->driver->owner))
220 return NULL;
221
222 return entity;
223}
224EXPORT_SYMBOL_GPL(media_entity_get);
225
226/*
227 * media_entity_put - Release the reference to the parent module
228 * @entity: The entity
229 *
230 * Release the reference count acquired by media_entity_get().
231 *
232 * The function will return immediately if @entity is NULL.
233 */
234void media_entity_put(struct media_entity *entity)
235{
236 if (entity == NULL)
237 return;
238
239 if (entity->parent->dev)
240 module_put(entity->parent->dev->driver->owner);
241}
242EXPORT_SYMBOL_GPL(media_entity_put);
243
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244/* -----------------------------------------------------------------------------
245 * Links management
246 */
247
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248static struct media_link *media_entity_add_link(struct media_entity *entity)
249{
250 if (entity->num_links >= entity->max_links) {
251 struct media_link *links = entity->links;
252 unsigned int max_links = entity->max_links + 2;
253 unsigned int i;
254
255 links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
256 if (links == NULL)
257 return NULL;
258
259 for (i = 0; i < entity->num_links; i++)
260 links[i].reverse->reverse = &links[i];
261
262 entity->max_links = max_links;
263 entity->links = links;
264 }
265
266 return &entity->links[entity->num_links++];
267}
268
269int
270media_entity_create_link(struct media_entity *source, u16 source_pad,
271 struct media_entity *sink, u16 sink_pad, u32 flags)
272{
273 struct media_link *link;
274 struct media_link *backlink;
275
276 BUG_ON(source == NULL || sink == NULL);
277 BUG_ON(source_pad >= source->num_pads);
278 BUG_ON(sink_pad >= sink->num_pads);
279
280 link = media_entity_add_link(source);
281 if (link == NULL)
282 return -ENOMEM;
283
284 link->source = &source->pads[source_pad];
285 link->sink = &sink->pads[sink_pad];
286 link->flags = flags;
287
288 /* Create the backlink. Backlinks are used to help graph traversal and
289 * are not reported to userspace.
290 */
291 backlink = media_entity_add_link(sink);
292 if (backlink == NULL) {
293 source->num_links--;
294 return -ENOMEM;
295 }
296
297 backlink->source = &source->pads[source_pad];
298 backlink->sink = &sink->pads[sink_pad];
299 backlink->flags = flags;
300
301 link->reverse = backlink;
302 backlink->reverse = link;
303
304 sink->num_backlinks++;
305
306 return 0;
307}
308EXPORT_SYMBOL_GPL(media_entity_create_link);
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309
310static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
311{
312 const u32 mask = MEDIA_LNK_FL_ENABLED;
313 int ret;
314
315 /* Notify both entities. */
316 ret = media_entity_call(link->source->entity, link_setup,
317 link->source, link->sink, flags);
318 if (ret < 0 && ret != -ENOIOCTLCMD)
319 return ret;
320
321 ret = media_entity_call(link->sink->entity, link_setup,
322 link->sink, link->source, flags);
323 if (ret < 0 && ret != -ENOIOCTLCMD) {
324 media_entity_call(link->source->entity, link_setup,
325 link->source, link->sink, link->flags);
326 return ret;
327 }
328
329 link->flags = (link->flags & ~mask) | (flags & mask);
330 link->reverse->flags = link->flags;
331
332 return 0;
333}
334
335/**
336 * __media_entity_setup_link - Configure a media link
337 * @link: The link being configured
338 * @flags: Link configuration flags
339 *
340 * The bulk of link setup is handled by the two entities connected through the
341 * link. This function notifies both entities of the link configuration change.
342 *
343 * If the link is immutable or if the current and new configuration are
344 * identical, return immediately.
345 *
346 * The user is expected to hold link->source->parent->mutex. If not,
347 * media_entity_setup_link() should be used instead.
348 */
349int __media_entity_setup_link(struct media_link *link, u32 flags)
350{
351 struct media_device *mdev;
352 struct media_entity *source, *sink;
353 int ret = -EBUSY;
354
355 if (link == NULL)
356 return -EINVAL;
357
358 if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
359 return link->flags == flags ? 0 : -EINVAL;
360
361 if (link->flags == flags)
362 return 0;
363
364 source = link->source->entity;
365 sink = link->sink->entity;
366
367 mdev = source->parent;
368
369 if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify) {
370 ret = mdev->link_notify(link->source, link->sink,
371 MEDIA_LNK_FL_ENABLED);
372 if (ret < 0)
373 return ret;
374 }
375
376 ret = __media_entity_setup_link_notify(link, flags);
377 if (ret < 0)
378 goto err;
379
380 if (!(flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
381 mdev->link_notify(link->source, link->sink, 0);
382
383 return 0;
384
385err:
386 if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify)
387 mdev->link_notify(link->source, link->sink, 0);
388
389 return ret;
390}
391
392int media_entity_setup_link(struct media_link *link, u32 flags)
393{
394 int ret;
395
396 mutex_lock(&link->source->entity->parent->graph_mutex);
397 ret = __media_entity_setup_link(link, flags);
398 mutex_unlock(&link->source->entity->parent->graph_mutex);
399
400 return ret;
401}
402EXPORT_SYMBOL_GPL(media_entity_setup_link);
403
404/**
405 * media_entity_find_link - Find a link between two pads
406 * @source: Source pad
407 * @sink: Sink pad
408 *
409 * Return a pointer to the link between the two entities. If no such link
410 * exists, return NULL.
411 */
412struct media_link *
413media_entity_find_link(struct media_pad *source, struct media_pad *sink)
414{
415 struct media_link *link;
416 unsigned int i;
417
418 for (i = 0; i < source->entity->num_links; ++i) {
419 link = &source->entity->links[i];
420
421 if (link->source->entity == source->entity &&
422 link->source->index == source->index &&
423 link->sink->entity == sink->entity &&
424 link->sink->index == sink->index)
425 return link;
426 }
427
428 return NULL;
429}
430EXPORT_SYMBOL_GPL(media_entity_find_link);
431
432/**
433 * media_entity_remote_source - Find the source pad at the remote end of a link
434 * @pad: Sink pad at the local end of the link
435 *
436 * Search for a remote source pad connected to the given sink pad by iterating
437 * over all links originating or terminating at that pad until an enabled link
438 * is found.
439 *
440 * Return a pointer to the pad at the remote end of the first found enabled
441 * link, or NULL if no enabled link has been found.
442 */
443struct media_pad *media_entity_remote_source(struct media_pad *pad)
444{
445 unsigned int i;
446
447 for (i = 0; i < pad->entity->num_links; i++) {
448 struct media_link *link = &pad->entity->links[i];
449
450 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
451 continue;
452
453 if (link->source == pad)
454 return link->sink;
455
456 if (link->sink == pad)
457 return link->source;
458 }
459
460 return NULL;
461
462}
463EXPORT_SYMBOL_GPL(media_entity_remote_source);