[PATCH v4l-utils v7 3/7] mediactl: Add media_entity_get_backlinks()

[Jacek Anaszewski <j.anaszewski@samsung.com>]

Add a new graph helper useful for discovering video pipeline.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 utils/media-ctl/libmediactl.c | 21 +++++++++++++++++++++
 utils/media-ctl/mediactl.h    | 15 +++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/utils/media-ctl/libmediactl.c b/utils/media-ctl/libmediactl.c
index 91ed003..155b65f 100644
--- a/utils/media-ctl/libmediactl.c
+++ b/utils/media-ctl/libmediactl.c
@@ -36,6 +36,7 @@
 #include <unistd.h>
 
 #include <linux/media.h>
+#include <linux/kdev_t.h>
 #include <linux/videodev2.h>
 
 #include "mediactl.h"
@@ -172,6 +173,26 @@ const struct media_entity_desc *media_entity_get_info(struct media_entity *entit
 	return &entity->info;
 }
 
+int media_entity_get_backlinks(struct media_entity *entity,
+				struct media_link **backlinks,
+				unsigned int *num_backlinks)
+{
+	unsigned int num_bklinks = 0;
+	int i;
+
+	if (entity == NULL || backlinks == NULL || num_backlinks == NULL)
+		return -EINVAL;
+
+	for (i = 0; i < entity->num_links; ++i)
+		if ((entity->links[i].flags & MEDIA_LNK_FL_ENABLED) &&
+		    (entity->links[i].sink->entity == entity))
+			backlinks[num_bklinks++] = &entity->links[i];
+
+	*num_backlinks = num_bklinks;
+
+	return 0;
+}
+
 /* -----------------------------------------------------------------------------
  * Open/close
  */
diff --git a/utils/media-ctl/mediactl.h b/utils/media-ctl/mediactl.h
index 336cbf9..b1f33cd 100644
--- a/utils/media-ctl/mediactl.h
+++ b/utils/media-ctl/mediactl.h
@@ -434,6 +434,20 @@ int media_parse_setup_link(struct media_device *media,
 int media_parse_setup_links(struct media_device *media, const char *p);
 
 /**
+ * @brief Get entity's enabled backlinks
+ * @param entity - media entity.
+ * @param backlinks - array of pointers to matching backlinks.
+ * @param num_backlinks - number of matching backlinks.
+ *
+ * Get links that are connected to the entity sink pads.
+ *
+ * @return 0 on success, or a negative error code on failure.
+ */
+int media_entity_get_backlinks(struct media_entity *entity,
+				struct media_link **backlinks,
+				unsigned int *num_backlinks);
+
+/**
  * @brief Get v4l2_subdev for the entity
  * @param entity - media entity
  *
@@ -443,4 +457,5 @@ int media_parse_setup_links(struct media_device *media, const char *p);
  */
 struct v4l2_subdev *media_entity_get_v4l2_subdev(struct media_entity *entity);
 
+
 #endif
-- 
1.9.1