[media] media: Entities, pads and links enumeration

Create the following two ioctls and implement them at the media device
level to enumerate entities, pads and links.

- MEDIA_IOC_ENUM_ENTITIES: Enumerate entities and their properties
- MEDIA_IOC_ENUM_LINKS: Enumerate all pads and links for a given entity

Entity IDs can be non-contiguous. Userspace applications should
enumerate entities using the MEDIA_ENT_ID_FLAG_NEXT flag. When the flag
is set in the entity ID, the MEDIA_IOC_ENUM_ENTITIES will return the
next entity with an ID bigger than the requested one.

Only forward links that originate at one of the entity's source pads are
returned during the enumeration process.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 92e0d4e..648a9d8 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -61,6 +61,117 @@ static int media_device_get_info(struct media_device *dev,
 	return copy_to_user(__info, &info, sizeof(*__info));
 }
 
+static struct media_entity *find_entity(struct media_device *mdev, u32 id)
+{
+	struct media_entity *entity;
+	int next = id & MEDIA_ENT_ID_FLAG_NEXT;
+
+	id &= ~MEDIA_ENT_ID_FLAG_NEXT;
+
+	spin_lock(&mdev->lock);
+
+	media_device_for_each_entity(entity, mdev) {
+		if ((entity->id == id && !next) ||
+		    (entity->id > id && next)) {
+			spin_unlock(&mdev->lock);
+			return entity;
+		}
+	}
+
+	spin_unlock(&mdev->lock);
+
+	return NULL;
+}
+
+static long media_device_enum_entities(struct media_device *mdev,
+				       struct media_entity_desc __user *uent)
+{
+	struct media_entity *ent;
+	struct media_entity_desc u_ent;
+
+	if (copy_from_user(&u_ent.id, &uent->id, sizeof(u_ent.id)))
+		return -EFAULT;
+
+	ent = find_entity(mdev, u_ent.id);
+
+	if (ent == NULL)
+		return -EINVAL;
+
+	u_ent.id = ent->id;
+	u_ent.name[0] = '\0';
+	if (ent->name)
+		strlcpy(u_ent.name, ent->name, sizeof(u_ent.name));
+	u_ent.type = ent->type;
+	u_ent.revision = ent->revision;
+	u_ent.flags = ent->flags;
+	u_ent.group_id = ent->group_id;
+	u_ent.pads = ent->num_pads;
+	u_ent.links = ent->num_links - ent->num_backlinks;
+	u_ent.v4l.major = ent->v4l.major;
+	u_ent.v4l.minor = ent->v4l.minor;
+	if (copy_to_user(uent, &u_ent, sizeof(u_ent)))
+		return -EFAULT;
+	return 0;
+}
+
+static void media_device_kpad_to_upad(const struct media_pad *kpad,
+				      struct media_pad_desc *upad)
+{
+	upad->entity = kpad->entity->id;
+	upad->index = kpad->index;
+	upad->flags = kpad->flags;
+}
+
+static long media_device_enum_links(struct media_device *mdev,
+				    struct media_links_enum __user *ulinks)
+{
+	struct media_entity *entity;
+	struct media_links_enum links;
+
+	if (copy_from_user(&links, ulinks, sizeof(links)))
+		return -EFAULT;
+
+	entity = find_entity(mdev, links.entity);
+	if (entity == NULL)
+		return -EINVAL;
+
+	if (links.pads) {
+		unsigned int p;
+
+		for (p = 0; p < entity->num_pads; p++) {
+			struct media_pad_desc pad;
+			media_device_kpad_to_upad(&entity->pads[p], &pad);
+			if (copy_to_user(&links.pads[p], &pad, sizeof(pad)))
+				return -EFAULT;
+		}
+	}
+
+	if (links.links) {
+		struct media_link_desc __user *ulink;
+		unsigned int l;
+
+		for (l = 0, ulink = links.links; l < entity->num_links; l++) {
+			struct media_link_desc link;
+
+			/* Ignore backlinks. */
+			if (entity->links[l].source->entity != entity)
+				continue;
+
+			media_device_kpad_to_upad(entity->links[l].source,
+						  &link.source);
+			media_device_kpad_to_upad(entity->links[l].sink,
+						  &link.sink);
+			link.flags = entity->links[l].flags;
+			if (copy_to_user(ulink, &link, sizeof(*ulink)))
+				return -EFAULT;
+			ulink++;
+		}
+	}
+	if (copy_to_user(ulinks, &links, sizeof(*ulinks)))
+		return -EFAULT;
+	return 0;
+}
+
 static long media_device_ioctl(struct file *filp, unsigned int cmd,
 			       unsigned long arg)
 {
@@ -74,6 +185,18 @@ static long media_device_ioctl(struct file *filp, unsigned int cmd,
 				(struct media_device_info __user *)arg);
 		break;
 
+	case MEDIA_IOC_ENUM_ENTITIES:
+		ret = media_device_enum_entities(dev,
+				(struct media_entity_desc __user *)arg);
+		break;
+
+	case MEDIA_IOC_ENUM_LINKS:
+		mutex_lock(&dev->graph_mutex);
+		ret = media_device_enum_links(dev,
+				(struct media_links_enum __user *)arg);
+		mutex_unlock(&dev->graph_mutex);
+		break;
+
 	default:
 		ret = -ENOIOCTLCMD;
 	}