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[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>
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Laurent Pinchart
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Mauro Carvalho Chehab
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Mar 22, 2011
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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 <unistd.h></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> |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,116 @@ | ||
| <refentry id="media-func-ioctl"> | ||
| <refmeta> | ||
| <refentrytitle>media ioctl()</refentrytitle> | ||
| &manvol; | ||
| </refmeta> | ||
|
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||
| <refnamediv> | ||
| <refname>media-ioctl</refname> | ||
| <refpurpose>Control a media device</refpurpose> | ||
| </refnamediv> | ||
|
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||
| <refsynopsisdiv> | ||
| <funcsynopsis> | ||
| <funcsynopsisinfo>#include <sys/ioctl.h></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> | ||
|
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||
| <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> |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,94 @@ | ||
| <refentry id="media-func-open"> | ||
| <refmeta> | ||
| <refentrytitle>media open()</refentrytitle> | ||
| &manvol; | ||
| </refmeta> | ||
|
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||
| <refnamediv> | ||
| <refname>media-open</refname> | ||
| <refpurpose>Open a media device</refpurpose> | ||
| </refnamediv> | ||
|
|
||
| <refsynopsisdiv> | ||
| <funcsynopsis> | ||
| <funcsynopsisinfo>#include <fcntl.h></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> |
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