1 files changed, 147 insertions, 0 deletions

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
new file mode 100644
index 000000000000..5c31df9ed765
--- /dev/null
+++ b/drivers/media/media-entity.c
@@ -0,0 +1,147 @@
+/*
+ * Media entity
+ *
+ * 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
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <media/media-entity.h>
+
+/**
+ * media_entity_init - Initialize a media entity
+ *
+ * @num_pads: Total number of sink and source pads.
+ * @extra_links: Initial estimate of the number of extra links.
+ * @pads: Array of 'num_pads' pads.
+ *
+ * The total number of pads is an intrinsic property of entities known by the
+ * entity driver, while the total number of links depends on hardware design
+ * and is an extrinsic property unknown to the entity driver. However, in most
+ * use cases the entity driver can guess the number of links which can safely
+ * be assumed to be equal to or larger than the number of pads.
+ *
+ * For those reasons the links array can be preallocated based on the entity
+ * driver guess and will be reallocated later if extra links need to be
+ * created.
+ *
+ * This function allocates a links array with enough space to hold at least
+ * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
+ * be set to the number of allocated elements.
+ *
+ * The pads array is managed by the entity driver and passed to
+ * media_entity_init() where its pointer will be stored in the entity structure.
+ */
+int
+media_entity_init(struct media_entity *entity, u16 num_pads,
+                  struct media_pad *pads, u16 extra_links)
+{
+        struct media_link *links;
+        unsigned int max_links = num_pads + extra_links;
+        unsigned int i;
+
+        links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
+        if (links == NULL)
+                return -ENOMEM;
+
+        entity->group_id = 0;
+        entity->max_links = max_links;
+        entity->num_links = 0;
+        entity->num_backlinks = 0;
+        entity->num_pads = num_pads;
+        entity->pads = pads;
+        entity->links = links;
+
+        for (i = 0; i < num_pads; i++) {
+                pads[i].entity = entity;
+                pads[i].index = i;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(media_entity_init);
+
+void
+media_entity_cleanup(struct media_entity *entity)
+{
+        kfree(entity->links);
+}
+EXPORT_SYMBOL_GPL(media_entity_cleanup);
+
+static struct media_link *media_entity_add_link(struct media_entity *entity)
+{
+        if (entity->num_links >= entity->max_links) {
+                struct media_link *links = entity->links;
+                unsigned int max_links = entity->max_links + 2;
+                unsigned int i;
+
+                links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
+                if (links == NULL)
+                        return NULL;
+
+                for (i = 0; i < entity->num_links; i++)
+                        links[i].reverse->reverse = &links[i];
+
+                entity->max_links = max_links;
+                entity->links = links;
+        }
+
+        return &entity->links[entity->num_links++];
+}
+
+int
+media_entity_create_link(struct media_entity *source, u16 source_pad,
+                         struct media_entity *sink, u16 sink_pad, u32 flags)
+{
+        struct media_link *link;
+        struct media_link *backlink;
+
+        BUG_ON(source == NULL || sink == NULL);
+        BUG_ON(source_pad >= source->num_pads);
+        BUG_ON(sink_pad >= sink->num_pads);
+
+        link = media_entity_add_link(source);
+        if (link == NULL)
+                return -ENOMEM;
+
+        link->source = &source->pads[source_pad];
+        link->sink = &sink->pads[sink_pad];
+        link->flags = flags;
+
+        /* Create the backlink. Backlinks are used to help graph traversal and
+         * are not reported to userspace.
+         */
+        backlink = media_entity_add_link(sink);
+        if (backlink == NULL) {
+                source->num_links--;
+                return -ENOMEM;
+        }
+
+        backlink->source = &source->pads[source_pad];
+        backlink->sink = &sink->pads[sink_pad];
+        backlink->flags = flags;
+
+        link->reverse = backlink;
+        backlink->reverse = link;
+
+        sink->num_backlinks++;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(media_entity_create_link);