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53e269c1 LP |
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> |
53e269c1 LP |
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 | */ | |
52 | int | |
53 | media_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 | } | |
79 | EXPORT_SYMBOL_GPL(media_entity_init); | |
80 | ||
81 | void | |
82 | media_entity_cleanup(struct media_entity *entity) | |
83 | { | |
84 | kfree(entity->links); | |
85 | } | |
86 | EXPORT_SYMBOL_GPL(media_entity_cleanup); | |
87 | ||
a5ccc48a SA |
88 | /* ----------------------------------------------------------------------------- |
89 | * Graph traversal | |
90 | */ | |
91 | ||
92 | static struct media_entity * | |
93 | media_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 */ | |
102 | static 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 | ||
114 | static 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 | */ | |
138 | void 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 | } | |
145 | EXPORT_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 | */ | |
159 | struct media_entity * | |
160 | media_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 | } | |
197 | EXPORT_SYMBOL_GPL(media_entity_graph_walk_next); | |
198 | ||
503c3d82 LP |
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 | */ | |
213 | struct 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 | } | |
224 | EXPORT_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 | */ | |
234 | void 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 | } | |
242 | EXPORT_SYMBOL_GPL(media_entity_put); | |
243 | ||
a5ccc48a SA |
244 | /* ----------------------------------------------------------------------------- |
245 | * Links management | |
246 | */ | |
247 | ||
53e269c1 LP |
248 | static 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 | ||
269 | int | |
270 | media_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 | } | |
308 | EXPORT_SYMBOL_GPL(media_entity_create_link); |