[media] media: Media device information query

Create the following ioctl and implement it at the media device level to
query device information.

- MEDIA_IOC_DEVICE_INFO: Query media device information

The ioctl and its data structure are defined in the new kernel header
linux/media.h available to userspace applications.

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

Documentation/DocBook/media-entities.tmpl

@@ -11,6 +11,10 @@
 <!ENTITY func-select "<link linkend='func-select'><function>select()</function></link>">
 <!ENTITY func-write "<link linkend='func-write'><function>write()</function></link>">
 
+<!ENTITY media-func-close "<link linkend='media-func-close'><function>close()</function></link>">
+<!ENTITY media-func-ioctl "<link linkend='media-func-ioctl'><function>ioctl()</function></link>">
+<!ENTITY media-func-open "<link linkend='media-func-open'><function>open()</function></link>">
+
 <!-- Ioctls -->
 <!ENTITY VIDIOC-CROPCAP "<link linkend='vidioc-cropcap'><constant>VIDIOC_CROPCAP</constant></link>">
 <!ENTITY VIDIOC-DBG-G-CHIP-IDENT "<link linkend='vidioc-dbg-g-chip-ident'><constant>VIDIOC_DBG_G_CHIP_IDENT</constant></link>">
@@ -87,6 +91,8 @@
 <!ENTITY VIDIOC-TRY-FMT "<link linkend='vidioc-g-fmt'><constant>VIDIOC_TRY_FMT</constant></link>">
 <!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>">
+
 <!-- Types -->
 <!ENTITY v4l2-std-id "<link linkend='v4l2-std-id'>v4l2_std_id</link>">
 
@@ -184,6 +190,8 @@
 <!ENTITY v4l2-vbi-format "struct&nbsp;<link linkend='v4l2-vbi-format'>v4l2_vbi_format</link>">
 <!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>">
+
 <!-- Error Codes -->
 <!ENTITY EACCES "<errorcode>EACCES</errorcode> error code">
 <!ENTITY EAGAIN "<errorcode>EAGAIN</errorcode> error code">
@@ -328,6 +336,10 @@
 <!ENTITY sub-media-indices SYSTEM "media-indices.tmpl">
 
 <!ENTITY sub-media-controller SYSTEM "v4l/media-controller.xml">
+<!ENTITY sub-media-open SYSTEM "v4l/media-func-open.xml">
+<!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">
 
 <!-- Function Reference -->
 <!ENTITY close SYSTEM "v4l/func-close.xml">

Documentation/DocBook/v4l/media-controller.xml

@@ -74,3 +74,13 @@
     pad to a sink pad.</para>
   </section>
 </chapter>
+
+<appendix id="media-user-func">
+  <title>Function Reference</title>
+  <!-- Keep this alphabetically sorted. -->
+  &sub-media-open;
+  &sub-media-close;
+  &sub-media-ioctl;
+  <!-- All ioctls go here. -->
+  &sub-media-ioc-device-info;
+</appendix>

Documentation/DocBook/v4l/media-func-close.xml

@@ -0,0 +1,59 @@
+<refentry id="media-func-close">
+  <refmeta>
+    <refentrytitle>media close()</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>media-close</refname>
+    <refpurpose>Close a media device</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;unistd.h&gt;</funcsynopsisinfo>
+      <funcprototype>
+	<funcdef>int <function>close</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>Closes the media device. Resources associated with the file descriptor
+    are freed. The device configuration remain unchanged.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para><function>close</function> returns 0 on success. On error, -1 is
+    returned, and <varname>errno</varname> is set appropriately. Possible error
+    codes are:</para>
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EBADF</errorcode></term>
+	<listitem>
+	  <para><parameter>fd</parameter> is not a valid open file descriptor.
+	  </para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>

Documentation/DocBook/v4l/media-func-ioctl.xml

@@ -0,0 +1,116 @@
+<refentry id="media-func-ioctl">
+  <refmeta>
+    <refentrytitle>media ioctl()</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>media-ioctl</refname>
+    <refpurpose>Control a media device</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;sys/ioctl.h&gt;</funcsynopsisinfo>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>void *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>Media ioctl request code as defined in the media.h header file,
+	  for example MEDIA_IOC_SETUP_LINK.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para>Pointer to a request-specific structure.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+    <para>The <function>ioctl()</function> function manipulates media device
+    parameters. The argument <parameter>fd</parameter> must be an open file
+    descriptor.</para>
+    <para>The ioctl <parameter>request</parameter> code specifies the media
+    function to be called. It has encoded in it whether the argument is an
+    input, output or read/write parameter, and the size of the argument
+    <parameter>argp</parameter> in bytes.</para>
+    <para>Macros and structures definitions specifying media ioctl requests and
+    their parameters are located in the media.h header file. All media ioctl
+    requests, their respective function and parameters are specified in
+    <xref linkend="media-user-func" />.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para><function>ioctl()</function> returns <returnvalue>0</returnvalue> on
+    success. On failure, <returnvalue>-1</returnvalue> is returned, and the
+    <varname>errno</varname> variable is set appropriately. Generic error codes
+    are listed below, and request-specific error codes are listed in the
+    individual requests descriptions.</para>
+    <para>When an ioctl that takes an output or read/write parameter fails,
+    the parameter remains unmodified.</para>
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EBADF</errorcode></term>
+	<listitem>
+	  <para><parameter>fd</parameter> is not a valid open file descriptor.
+	  </para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EFAULT</errorcode></term>
+	<listitem>
+	  <para><parameter>argp</parameter> references an inaccessible memory
+	  area.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The <parameter>request</parameter> or the data pointed to by
+	  <parameter>argp</parameter> is not valid. This is a very common error
+	  code, see the individual ioctl requests listed in
+	  <xref linkend="media-user-func" /> for actual causes.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENOMEM</errorcode></term>
+	<listitem>
+	  <para>Insufficient kernel memory was available to complete the
+	  request.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENOTTY</errorcode></term>
+	<listitem>
+	  <para><parameter>fd</parameter> is  not  associated  with  a character
+	  special device.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>

Documentation/DocBook/v4l/media-func-open.xml

@@ -0,0 +1,94 @@
+<refentry id="media-func-open">
+  <refmeta>
+    <refentrytitle>media open()</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>media-open</refname>
+    <refpurpose>Open a media device</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;fcntl.h&gt;</funcsynopsisinfo>
+      <funcprototype>
+	<funcdef>int <function>open</function></funcdef>
+	<paramdef>const char *<parameter>device_name</parameter></paramdef>
+	<paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>device_name</parameter></term>
+	<listitem>
+	  <para>Device to be opened.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>flags</parameter></term>
+	<listitem>
+	  <para>Open flags. Access mode must be either <constant>O_RDONLY</constant>
+	  or <constant>O_RDWR</constant>. Other flags have no effect.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+  <refsect1>
+    <title>Description</title>
+    <para>To open a media device applications call <function>open()</function>
+    with the desired device name. The function has no side effects; the device
+    configuration remain unchanged.</para>
+    <para>When the device is opened in read-only mode, attemps to modify its
+    configuration will result in an error, and <varname>errno</varname> will be
+    set to <errorcode>EBADF</errorcode>.</para>
+  </refsect1>
+  <refsect1>
+    <title>Return Value</title>
+
+    <para><function>open</function> returns the new file descriptor on success.
+    On error, -1 is returned, and <varname>errno</varname> is set appropriately.
+    Possible error codes are:</para>
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EACCES</errorcode></term>
+	<listitem>
+	  <para>The requested access to the file is not allowed.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EMFILE</errorcode></term>
+	<listitem>
+	  <para>The  process  already  has  the  maximum number of files open.
+	  </para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENFILE</errorcode></term>
+	<listitem>
+	  <para>The system limit on the total number of open files has been
+	  reached.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENOMEM</errorcode></term>
+	<listitem>
+	  <para>Insufficient kernel memory was available.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENXIO</errorcode></term>
+	<listitem>
+	  <para>No device corresponding to this device special file exists.
+	  </para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>

Documentation/DocBook/v4l/media-ioc-device-info.xml

@@ -0,0 +1,132 @@
+<refentry id="media-ioc-device-info">
+  <refmeta>
+    <refentrytitle>ioctl MEDIA_IOC_DEVICE_INFO</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>MEDIA_IOC_DEVICE_INFO</refname>
+    <refpurpose>Query device information</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_device_info *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>MEDIA_IOC_DEVICE_INFO</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>All media devices must support the <constant>MEDIA_IOC_DEVICE_INFO</constant>
+    ioctl. To query device information, applications call the ioctl with a
+    pointer to a &media-device-info;. The driver fills the structure and returns
+    the information to the application.
+    The ioctl never fails.</para>
+
+    <table pgwide="1" frame="none" id="media-device-info">
+      <title>struct <structname>media_device_info</structname></title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>char</entry>
+	    <entry><structfield>driver</structfield>[16]</entry>
+	    <entry><para>Name of the driver implementing the media API as a
+	    NUL-terminated ASCII string. The driver version is stored in the
+	    <structfield>driver_version</structfield> field.</para>
+	    <para>Driver specific applications can use this information to
+	    verify the driver identity. It is also useful to work around
+	    known bugs, or to identify drivers in error reports.</para></entry>
+	  </row>
+	  <row>
+	    <entry>char</entry>
+	    <entry><structfield>model</structfield>[32]</entry>
+	    <entry>Device model name as a NUL-terminated UTF-8 string. The
+	    device version is stored in the <structfield>device_version</structfield>
+	    field and is not be appended to the model name.</entry>
+	  </row>
+	  <row>
+	    <entry>char</entry>
+	    <entry><structfield>serial</structfield>[40]</entry>
+	    <entry>Serial number as a NUL-terminated ASCII string.</entry>
+	  </row>
+	  <row>
+	    <entry>char</entry>
+	    <entry><structfield>bus_info</structfield>[32]</entry>
+	    <entry>Location of the device in the system as a NUL-terminated
+	    ASCII string. This includes the bus type name (PCI, USB, ...) and a
+	    bus-specific identifier.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>media_version</structfield></entry>
+	    <entry>Media API version, formatted with the
+	    <constant>KERNEL_VERSION()</constant> macro.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>hw_revision</structfield></entry>
+	    <entry>Hardware device revision in a driver-specific format.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>media_version</structfield></entry>
+	    <entry>Media device driver version, formatted with the
+	    <constant>KERNEL_VERSION()</constant> macro. Together with the
+	    <structfield>driver</structfield> field this identifies a particular
+	    driver.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>reserved</structfield>[31]</entry>
+	    <entry>Reserved for future extensions. Drivers and applications must
+	    set this array to zero.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+    <para>The <structfield>serial</structfield> and <structfield>bus_info</structfield>
+    fields can be used to distinguish between multiple instances of otherwise
+    identical hardware. The serial number takes precedence when provided and can
+    be assumed to be unique. If the serial number is an empty string, the
+    <structfield>bus_info</structfield> field can be used instead. The
+    <structfield>bus_info</structfield> field is guaranteed to be unique, but
+    can vary across reboots or device unplug/replug.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return value</title>
+    <para>This function doesn't return specific error codes.</para>
+  </refsect1>
+</refentry>

drivers/media/media-device.c

@@ -22,13 +22,70 @@
 
 #include <linux/types.h>
 #include <linux/ioctl.h>
+#include <linux/media.h>
 
 #include <media/media-device.h>
 #include <media/media-devnode.h>
 #include <media/media-entity.h>
 
+/* -----------------------------------------------------------------------------
+ * Userspace API
+ */
+
+static int media_device_open(struct file *filp)
+{
+	return 0;
+}
+
+static int media_device_close(struct file *filp)
+{
+	return 0;
+}
+
+static int media_device_get_info(struct media_device *dev,
+				 struct media_device_info __user *__info)
+{
+	struct media_device_info info;
+
+	memset(&info, 0, sizeof(info));
+
+	strlcpy(info.driver, dev->dev->driver->name, sizeof(info.driver));
+	strlcpy(info.model, dev->model, sizeof(info.model));
+	strlcpy(info.serial, dev->serial, sizeof(info.serial));
+	strlcpy(info.bus_info, dev->bus_info, sizeof(info.bus_info));
+
+	info.media_version = MEDIA_API_VERSION;
+	info.hw_revision = dev->hw_revision;
+	info.driver_version = dev->driver_version;
+
+	return copy_to_user(__info, &info, sizeof(*__info));
+}
+
+static long media_device_ioctl(struct file *filp, unsigned int cmd,
+			       unsigned long arg)
+{
+	struct media_devnode *devnode = media_devnode_data(filp);
+	struct media_device *dev = to_media_device(devnode);
+	long ret;
+
+	switch (cmd) {
+	case MEDIA_IOC_DEVICE_INFO:
+		ret = media_device_get_info(dev,
+				(struct media_device_info __user *)arg);
+		break;
+
+	default:
+		ret = -ENOIOCTLCMD;
+	}
+
+	return ret;
+}
+
 static const struct media_file_operations media_device_fops = {
 	.owner = THIS_MODULE,
+	.open = media_device_open,
+	.ioctl = media_device_ioctl,
+	.release = media_device_close,
 };
 
 /* -----------------------------------------------------------------------------

include/linux/Kbuild

@@ -233,6 +233,7 @@ header-y += magic.h
 header-y += major.h
 header-y += map_to_7segment.h
 header-y += matroxfb.h
+header-y += media.h
 header-y += mempolicy.h
 header-y += meye.h
 header-y += mii.h

include/linux/media.h

@@ -0,0 +1,45 @@
+/*
+ * Multimedia device API
+ *
+ * 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
+ */
+
+#ifndef __LINUX_MEDIA_H
+#define __LINUX_MEDIA_H
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+#include <linux/version.h>
+
+#define MEDIA_API_VERSION	KERNEL_VERSION(0, 1, 0)
+
+struct media_device_info {
+	char driver[16];
+	char model[32];
+	char serial[40];
+	char bus_info[32];
+	__u32 media_version;
+	__u32 hw_revision;
+	__u32 driver_version;
+	__u32 reserved[31];
+};
+
+#define MEDIA_IOC_DEVICE_INFO		_IOWR('M', 1, struct media_device_info)
+
+#endif /* __LINUX_MEDIA_H */