diff mbox

[v9,07/12] media: Entities, pads and links enumeration

Message ID 1297686067-9666-8-git-send-email-laurent.pinchart@ideasonboard.com (mailing list archive)
State RFC
Headers show

Commit Message

Laurent Pinchart Feb. 14, 2011, 12:21 p.m. UTC
None
diff mbox

Patch

diff --git a/Documentation/DocBook/media-entities.tmpl b/Documentation/DocBook/media-entities.tmpl
index 6af3375..6e7dae4 100644
--- a/Documentation/DocBook/media-entities.tmpl
+++ b/Documentation/DocBook/media-entities.tmpl
@@ -92,6 +92,8 @@ 
 <!ENTITY VIDIOC-UNSUBSCRIBE-EVENT "<link linkend='vidioc-subscribe-event'><constant>VIDIOC_UNSUBSCRIBE_EVENT</constant></link>">
 
 <!ENTITY MEDIA-IOC-DEVICE-INFO "<link linkend='media-ioc-device-info'><constant>MEDIA_IOC_DEVICE_INFO</constant></link>">
+<!ENTITY MEDIA-IOC-ENUM-ENTITIES "<link linkend='media-ioc-enum-entities'><constant>MEDIA_IOC_ENUM_ENTITIES</constant></link>">
+<!ENTITY MEDIA-IOC-ENUM-LINKS "<link linkend='media-ioc-enum-links'><constant>MEDIA_IOC_ENUM_LINKS</constant></link>">
 
 <!-- Types -->
 <!ENTITY v4l2-std-id "<link linkend='v4l2-std-id'>v4l2_std_id</link>">
@@ -188,6 +190,10 @@ 
 <!ENTITY v4l2-window "struct&nbsp;<link linkend='v4l2-window'>v4l2_window</link>">
 
 <!ENTITY media-device-info "struct&nbsp;<link linkend='media-device-info'>media_device_info</link>">
+<!ENTITY media-entity-desc "struct&nbsp;<link linkend='media-entity-desc'>media_entity_desc</link>">
+<!ENTITY media-links-enum "struct&nbsp;<link linkend='media-links-enum'>media_links_enum</link>">
+<!ENTITY media-pad-desc "struct&nbsp;<link linkend='media-pad-desc'>media_pad_desc</link>">
+<!ENTITY media-link-desc "struct&nbsp;<link linkend='media-link-desc'>media_link_desc</link>">
 
 <!-- Error Codes -->
 <!ENTITY EACCES "<errorcode>EACCES</errorcode> error code">
@@ -334,6 +340,8 @@ 
 <!ENTITY sub-media-close SYSTEM "v4l/media-func-close.xml">
 <!ENTITY sub-media-ioctl SYSTEM "v4l/media-func-ioctl.xml">
 <!ENTITY sub-media-ioc-device-info SYSTEM "v4l/media-ioc-device-info.xml">
+<!ENTITY sub-media-ioc-enum-entities SYSTEM "v4l/media-ioc-enum-entities.xml">
+<!ENTITY sub-media-ioc-enum-links SYSTEM "v4l/media-ioc-enum-links.xml">
 
 <!-- Function Reference -->
 <!ENTITY close SYSTEM "v4l/func-close.xml">
diff --git a/Documentation/DocBook/v4l/media-controller.xml b/Documentation/DocBook/v4l/media-controller.xml
index a46b786..2c4fd2b 100644
--- a/Documentation/DocBook/v4l/media-controller.xml
+++ b/Documentation/DocBook/v4l/media-controller.xml
@@ -83,4 +83,6 @@ 
   &sub-media-ioctl;
   <!-- All ioctls go here. -->
   &sub-media-ioc-device-info;
+  &sub-media-ioc-enum-entities;
+  &sub-media-ioc-enum-links;
 </appendix>
diff --git a/Documentation/DocBook/v4l/media-ioc-device-info.xml b/Documentation/DocBook/v4l/media-ioc-device-info.xml
index 278a312..1f32373 100644
--- a/Documentation/DocBook/v4l/media-ioc-device-info.xml
+++ b/Documentation/DocBook/v4l/media-ioc-device-info.xml
@@ -27,7 +27,8 @@ 
       <varlistentry>
 	<term><parameter>fd</parameter></term>
 	<listitem>
-	  <para>&fd;</para>
+	  <para>File descriptor returned by
+	  <link linkend='media-func-open'><function>open()</function></link>.</para>
 	</listitem>
       </varlistentry>
       <varlistentry>
diff --git a/Documentation/DocBook/v4l/media-ioc-enum-entities.xml b/Documentation/DocBook/v4l/media-ioc-enum-entities.xml
new file mode 100644
index 0000000..13d0cc4
--- /dev/null
+++ b/Documentation/DocBook/v4l/media-ioc-enum-entities.xml
@@ -0,0 +1,308 @@ 
+<refentry id="media-ioc-enum-entities">
+  <refmeta>
+    <refentrytitle>ioctl MEDIA_IOC_ENUM_ENTITIES</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>MEDIA_IOC_ENUM_ENTITIES</refname>
+    <refpurpose>Enumerate entities and their properties</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct media_entity_desc *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>File descriptor returned by
+	  <link linkend='media-func-open'><function>open()</function></link>.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>MEDIA_IOC_ENUM_ENTITIES</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+    <para>To query the attributes of an entity, applications set the id field
+    of a &media-entity-desc; structure and call the MEDIA_IOC_ENUM_ENTITIES
+    ioctl with a pointer to this structure. The driver fills the rest of the
+    structure or returns an &EINVAL; when the id is invalid.</para>
+    <para>Entities can be enumerated by or'ing the id with the
+    <constant>MEDIA_ENT_ID_FLAG_NEXT</constant> flag. The driver will return
+    information about the entity with the smallest id strictly larger than the
+    requested one ('next entity'), or the &EINVAL; if there is none.</para>
+    <para>Entity IDs can be non-contiguous. Applications must
+    <emphasis>not</emphasis> try to enumerate entities by calling
+    MEDIA_IOC_ENUM_ENTITIES with increasing id's until they get an error.</para>
+    <para>Two or more entities that share a common non-zero
+    <structfield>group_id</structfield> value are considered as logically
+    grouped. Groups are used to report
+    <itemizedlist>
+      <listitem>ALSA, VBI and video nodes that carry the same media
+      stream</listitem>
+      <listitem>lens and flash controllers associated with a sensor</listitem>
+    </itemizedlist>
+    </para>
+
+    <table pgwide="1" frame="none" id="media-entity-desc">
+      <title>struct <structname>media_entity_desc</structname></title>
+      <tgroup cols="5">
+	<colspec colname="c1" />
+	<colspec colname="c2" />
+	<colspec colname="c3" />
+	<colspec colname="c4" />
+	<colspec colname="c5" />
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>id</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Entity id, set by the application. When the id is or'ed with
+	    <constant>MEDIA_ENT_ID_FLAG_NEXT</constant>, the driver clears the
+	    flag and returns the first entity with a larger id.</entry>
+	  </row>
+	  <row>
+	    <entry>char</entry>
+	    <entry><structfield>name</structfield>[32]</entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Entity name as an UTF-8 NULL-terminated string.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>type</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Entity type, see <xref linkend="media-entity-type" /> for details.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>revision</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Entity revision in a driver/hardware specific format.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>flags</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Entity flags, see <xref linkend="media-entity-flag" /> for details.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>group_id</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Entity group ID</entry>
+	  </row>
+	  <row>
+	    <entry>__u16</entry>
+	    <entry><structfield>pads</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Number of pads</entry>
+	  </row>
+	  <row>
+	    <entry>__u16</entry>
+	    <entry><structfield>links</structfield></entry>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>Total number of outbound links. Inbound links are not counted
+	    in this field.</entry>
+	  </row>
+	  <row>
+	    <entry>union</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>struct</entry>
+	    <entry><structfield>v4l</structfield></entry>
+	    <entry></entry>
+	    <entry>Valid for V4L sub-devices and nodes only.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>major</structfield></entry>
+	    <entry>V4L device node major number. For V4L sub-devices with no
+	    device node, set by the driver to 0.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>minor</structfield></entry>
+	    <entry>V4L device node minor number. For V4L sub-devices with no
+	    device node, set by the driver to 0.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>struct</entry>
+	    <entry><structfield>fb</structfield></entry>
+	    <entry></entry>
+	    <entry>Valid for frame buffer nodes only.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>major</structfield></entry>
+	    <entry>Frame buffer device node major number.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>minor</structfield></entry>
+	    <entry>Frame buffer device node minor number.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>struct</entry>
+	    <entry><structfield>alsa</structfield></entry>
+	    <entry></entry>
+	    <entry>Valid for ALSA devices only.</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>card</structfield></entry>
+	    <entry>ALSA card number</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>device</structfield></entry>
+	    <entry>ALSA device number</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry></entry>
+	    <entry>__u32</entry>
+	    <entry><structfield>subdevice</structfield></entry>
+	    <entry>ALSA sub-device number</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>int</entry>
+	    <entry><structfield>dvb</structfield></entry>
+	    <entry></entry>
+	    <entry>DVB card number</entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>__u8</entry>
+	    <entry><structfield>raw</structfield>[180]</entry>
+	    <entry></entry>
+	    <entry></entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="media-entity-type">
+      <title>Media entity types</title>
+      <tgroup cols="2">
+        <colspec colname="c1"/>
+        <colspec colname="c2"/>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_DEVNODE</constant></entry>
+	    <entry>Unknown device node</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_DEVNODE_V4L</constant></entry>
+	    <entry>V4L video, radio or vbi device node</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_DEVNODE_FB</constant></entry>
+	    <entry>Frame buffer device node</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_DEVNODE_ALSA</constant></entry>
+	    <entry>ALSA card</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_DEVNODE_DVB</constant></entry>
+	    <entry>DVB card</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV</constant></entry>
+	    <entry>Unknown V4L sub-device</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_SENSOR</constant></entry>
+	    <entry>Video sensor</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_FLASH</constant></entry>
+	    <entry>Flash controller</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_LENS</constant></entry>
+	    <entry>Lens controller</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="media-entity-flag">
+      <title>Media entity flags</title>
+      <tgroup cols="2">
+        <colspec colname="c1"/>
+        <colspec colname="c2"/>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>MEDIA_ENT_FL_DEFAULT</constant></entry>
+	    <entry>Default entity for its type. Used to discover the default
+	    audio, VBI and video devices, the default camera sensor, ...</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The &media-entity-desc; <structfield>id</structfield> references
+	  a non-existing entity.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>
diff --git a/Documentation/DocBook/v4l/media-ioc-enum-links.xml b/Documentation/DocBook/v4l/media-ioc-enum-links.xml
new file mode 100644
index 0000000..4b08e55
--- /dev/null
+++ b/Documentation/DocBook/v4l/media-ioc-enum-links.xml
@@ -0,0 +1,202 @@ 
+<refentry id="media-ioc-enum-links">
+  <refmeta>
+    <refentrytitle>ioctl MEDIA_IOC_ENUM_LINKS</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>MEDIA_IOC_ENUM_LINKS</refname>
+    <refpurpose>Enumerate all pads and links for a given entity</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct media_links_enum *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>File descriptor returned by
+	  <link linkend='media-func-open'><function>open()</function></link>.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>MEDIA_IOC_ENUM_LINKS</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>To enumerate pads and/or links for a given entity, applications set
+    the entity field of a &media-links-enum; structure and initialize the
+    &media-pad-desc; and &media-link-desc; structure arrays pointed by the
+    <structfield>pads</structfield> and <structfield>links</structfield> fields.
+    They then call the MEDIA_IOC_ENUM_LINKS ioctl with a pointer to this
+    structure.</para>
+    <para>If the <structfield>pads</structfield> field is not NULL, the driver
+    fills the <structfield>pads</structfield> array with information about the
+    entity's pads. The array must have enough room to store all the entity's
+    pads. The number of pads can be retrieved with the &MEDIA-IOC-ENUM-ENTITIES;
+    ioctl.</para>
+    <para>If the <structfield>links</structfield> field is not NULL, the driver
+    fills the <structfield>links</structfield> array with information about the
+    entity's outbound links. The array must have enough room to store all the
+    entity's outbound links. The number of outbound links can be retrieved with
+    the &MEDIA-IOC-ENUM-ENTITIES; ioctl.</para>
+    <para>Only forward links that originate at one of the entity's source pads
+    are returned during the enumeration process.</para>
+
+    <table pgwide="1" frame="none" id="media-links-enum">
+      <title>struct <structname>media_links_enum</structname></title>
+      <tgroup cols="3">
+        &cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>entity</structfield></entry>
+	    <entry>Entity id, set by the application.</entry>
+	  </row>
+	  <row>
+	    <entry>struct &media-pad-desc;</entry>
+	    <entry>*<structfield>pads</structfield></entry>
+	    <entry>Pointer to a pads array allocated by the application. Ignored
+	    if NULL.</entry>
+	  </row>
+	  <row>
+	    <entry>struct &media-link-desc;</entry>
+	    <entry>*<structfield>links</structfield></entry>
+	    <entry>Pointer to a links array allocated by the application. Ignored
+	    if NULL.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table pgwide="1" frame="none" id="media-pad-desc">
+      <title>struct <structname>media_pad_desc</structname></title>
+      <tgroup cols="3">
+        &cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>entity</structfield></entry>
+	    <entry>ID of the entity this pad belongs to.</entry>
+	  </row>
+	  <row>
+	    <entry>__u16</entry>
+	    <entry><structfield>index</structfield></entry>
+	    <entry>0-based pad index.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>flags</structfield></entry>
+	    <entry>Pad flags, see <xref linkend="media-pad-flag" /> for more details.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="media-pad-flag">
+      <title>Media pad flags</title>
+      <tgroup cols="2">
+        <colspec colname="c1"/>
+        <colspec colname="c2"/>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>MEDIA_PAD_FL_SINK</constant></entry>
+	    <entry>Input pad, relative to the entity. Input pads sink data and
+	    are targets of links.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_PAD_FL_SOURCE</constant></entry>
+	    <entry>Output pad, relative to the entity. Output pads source data
+	    and are origins of links.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table pgwide="1" frame="none" id="media-link-desc">
+      <title>struct <structname>media_links_desc</structname></title>
+      <tgroup cols="3">
+        &cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>struct &media-pad-desc;</entry>
+	    <entry><structfield>source</structfield></entry>
+	    <entry>Pad at the origin of this link.</entry>
+	  </row>
+	  <row>
+	    <entry>struct &media-pad-desc;</entry>
+	    <entry><structfield>sink</structfield></entry>
+	    <entry>Pad at the target of this link.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>flags</structfield></entry>
+	    <entry>Link flags, see <xref linkend="media-link-flag" /> for more details.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="media-link-flag">
+      <title>Media link flags</title>
+      <tgroup cols="2">
+        <colspec colname="c1"/>
+        <colspec colname="c2"/>
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>MEDIA_LNK_FL_ENABLED</constant></entry>
+	    <entry>The link is enabled and can be used to transfer media data.
+	    When two or more links target a sink pad, only one of them can be
+	    enabled at a time.</entry>
+	  </row>
+	  <row>
+	    <entry><constant>MEDIA_LNK_FL_IMMUTABLE</constant></entry>
+	    <entry>The link enabled state can't be modified at runtime. An
+	    immutable link is always enabled.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+    <para>One and only one of <constant>MEDIA_PAD_FL_SINK</constant> and
+    <constant>MEDIA_PAD_FL_SOURCE</constant> must be set for every pad.</para>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The &media-links-enum; <structfield>id</structfield> references
+	  a non-existing entity.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>
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;
 	}
diff --git a/include/linux/media.h b/include/linux/media.h
index 64090db..17c93a4 100644
--- a/include/linux/media.h
+++ b/include/linux/media.h
@@ -40,6 +40,91 @@  struct media_device_info {
 	__u32 reserved[31];
 };
 
+#define MEDIA_ENT_ID_FLAG_NEXT		(1 << 31)
+
+#define MEDIA_ENT_TYPE_SHIFT		16
+#define MEDIA_ENT_TYPE_MASK		0x00ff0000
+#define MEDIA_ENT_SUBTYPE_MASK		0x0000ffff
+
+#define MEDIA_ENT_T_DEVNODE		(1 << MEDIA_ENT_TYPE_SHIFT)
+#define MEDIA_ENT_T_DEVNODE_V4L		(MEDIA_ENT_T_DEVNODE + 1)
+#define MEDIA_ENT_T_DEVNODE_FB		(MEDIA_ENT_T_DEVNODE + 2)
+#define MEDIA_ENT_T_DEVNODE_ALSA	(MEDIA_ENT_T_DEVNODE + 3)
+#define MEDIA_ENT_T_DEVNODE_DVB		(MEDIA_ENT_T_DEVNODE + 4)
+
+#define MEDIA_ENT_T_V4L2_SUBDEV		(2 << MEDIA_ENT_TYPE_SHIFT)
+#define MEDIA_ENT_T_V4L2_SUBDEV_SENSOR	(MEDIA_ENT_T_V4L2_SUBDEV + 1)
+#define MEDIA_ENT_T_V4L2_SUBDEV_FLASH	(MEDIA_ENT_T_V4L2_SUBDEV + 2)
+#define MEDIA_ENT_T_V4L2_SUBDEV_LENS	(MEDIA_ENT_T_V4L2_SUBDEV + 3)
+
+#define MEDIA_ENT_FL_DEFAULT		(1 << 0)
+
+struct media_entity_desc {
+	__u32 id;
+	char name[32];
+	__u32 type;
+	__u32 revision;
+	__u32 flags;
+	__u32 group_id;
+	__u16 pads;
+	__u16 links;
+
+	__u32 reserved[4];
+
+	union {
+		/* Node specifications */
+		struct {
+			__u32 major;
+			__u32 minor;
+		} v4l;
+		struct {
+			__u32 major;
+			__u32 minor;
+		} fb;
+		struct {
+			__u32 card;
+			__u32 device;
+			__u32 subdevice;
+		} alsa;
+		int dvb;
+
+		/* Sub-device specifications */
+		/* Nothing needed yet */
+		__u8 raw[184];
+	};
+};
+
+#define MEDIA_PAD_FL_SINK		(1 << 0)
+#define MEDIA_PAD_FL_SOURCE		(1 << 1)
+
+struct media_pad_desc {
+	__u32 entity;		/* entity ID */
+	__u16 index;		/* pad index */
+	__u32 flags;		/* pad flags */
+	__u32 reserved[2];
+};
+
+#define MEDIA_LNK_FL_ENABLED		(1 << 0)
+#define MEDIA_LNK_FL_IMMUTABLE		(1 << 1)
+
+struct media_link_desc {
+	struct media_pad_desc source;
+	struct media_pad_desc sink;
+	__u32 flags;
+	__u32 reserved[2];
+};
+
+struct media_links_enum {
+	__u32 entity;
+	/* Should have enough room for pads elements */
+	struct media_pad_desc __user *pads;
+	/* Should have enough room for links elements */
+	struct media_link_desc __user *links;
+	__u32 reserved[4];
+};
+
 #define MEDIA_IOC_DEVICE_INFO		_IOWR('M', 1, struct media_device_info)
+#define MEDIA_IOC_ENUM_ENTITIES		_IOWR('M', 2, struct media_entity_desc)
+#define MEDIA_IOC_ENUM_LINKS		_IOWR('M', 3, struct media_links_enum)
 
 #endif /* __LINUX_MEDIA_H */
diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index a9b31d9..51bdafc 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -24,29 +24,7 @@ 
 #define _MEDIA_ENTITY_H
 
 #include <linux/list.h>
-
-#define MEDIA_ENT_TYPE_SHIFT		16
-#define MEDIA_ENT_TYPE_MASK		0x00ff0000
-#define MEDIA_ENT_SUBTYPE_MASK		0x0000ffff
-
-#define MEDIA_ENT_T_DEVNODE		(1 << MEDIA_ENT_TYPE_SHIFT)
-#define MEDIA_ENT_T_DEVNODE_V4L		(MEDIA_ENT_T_DEVNODE + 1)
-#define MEDIA_ENT_T_DEVNODE_FB		(MEDIA_ENT_T_DEVNODE + 2)
-#define MEDIA_ENT_T_DEVNODE_ALSA	(MEDIA_ENT_T_DEVNODE + 3)
-#define MEDIA_ENT_T_DEVNODE_DVB		(MEDIA_ENT_T_DEVNODE + 4)
-
-#define MEDIA_ENT_T_V4L2_SUBDEV		(2 << MEDIA_ENT_TYPE_SHIFT)
-#define MEDIA_ENT_T_V4L2_SUBDEV_SENSOR	(MEDIA_ENT_T_V4L2_SUBDEV + 1)
-#define MEDIA_ENT_T_V4L2_SUBDEV_FLASH	(MEDIA_ENT_T_V4L2_SUBDEV + 2)
-#define MEDIA_ENT_T_V4L2_SUBDEV_LENS	(MEDIA_ENT_T_V4L2_SUBDEV + 3)
-
-#define MEDIA_ENT_FL_DEFAULT		(1 << 0)
-
-#define MEDIA_LNK_FL_ENABLED		(1 << 0)
-#define MEDIA_LNK_FL_IMMUTABLE		(1 << 1)
-
-#define MEDIA_PAD_FL_SINK		(1 << 0)
-#define MEDIA_PAD_FL_SOURCE		(1 << 1)
+#include <linux/media.h>
 
 struct media_link {
 	struct media_pad *source;	/* Source pad */