Commit 5c04dcea authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
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docs: ioctl: convert to ReST



Rename the iio documentation files to ReST, add an
index for them and adjust in order to produce a nice html
output via the Sphinx build system.

The cdrom.txt and hdio.txt have their own particular syntax.
In order to speedup the conversion, I used a small ancillary
perl script:

	my $d;
	$d .= $_ while(<>);
	$d =~ s/(\nCDROM\S+)\s+(\w[^\n]*)/$1\n\t$2\n/g;
	$d =~ s/(\nHDIO\S+)\s+(\w[^\n]*)/$1\n\t$2\n/g;
	$d =~ s/(\n\s*usage:)[\s\n]*(\w[^\n]*)/$1:\n\n\t  $2\n/g;
	$d =~ s/(\n\s*)(E\w+[\s\n]*\w[^\n]*)/$1- $2/g;
	$d =~ s/(\n\s*)(inputs|outputs|notes):\s*(\w[^\n]*)/$1$2:\n\t\t$3\n/g;
	print $d;

It basically add blank lines on a few interesting places. The
script is not perfect: still several things require manual work,
but it saved quite some time doing some obvious stuff.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent 08536105
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=================================
(How to avoid) Botching up ioctls
=================================

+1233 −0
Original line number Diff line number Diff line
		Summary of CDROM ioctl calls.
============================
Summary of CDROM ioctl calls
============================

		Edward A. Falk <efalk@google.com>
- Edward A. Falk <efalk@google.com>

November, 2004

@@ -12,6 +13,7 @@ in drivers/cdrom/cdrom.c and drivers/block/scsi_ioctl.c
ioctl values are listed in <linux/cdrom.h>.  As of this writing, they
are as follows:

	======================	===============================================
	CDROMPAUSE		Pause Audio Operation
	CDROMRESUME		Resume paused Audio Operation
	CDROMPLAYMSF		Play Audio MSF (struct cdrom_msf)
@@ -65,16 +67,13 @@ are as follows:
	CDROM_SEND_PACKET	send a packet to the drive
	CDROM_NEXT_WRITABLE	get next writable block
	CDROM_LAST_WRITTEN	get last block written on disc
	======================	===============================================


The information that follows was determined from reading kernel source
code.  It is likely that some corrections will be made over time.






------------------------------------------------------------------------------

General:

@@ -91,266 +90,361 @@ General:
	Unless otherwise specified, all data structures and constants
	are defined in <linux/cdrom.h>

------------------------------------------------------------------------------


CDROMPAUSE
	Pause Audio Operation

CDROMPAUSE			Pause Audio Operation

	usage:
	usage::

	  ioctl(fd, CDROMPAUSE, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.


CDROMRESUME			Resume paused Audio Operation
CDROMRESUME
	Resume paused Audio Operation

	usage:

	usage::

	  ioctl(fd, CDROMRESUME, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.


CDROMPLAYMSF			Play Audio MSF (struct cdrom_msf)
CDROMPLAYMSF
	Play Audio MSF

	(struct cdrom_msf)

	usage:

	usage::

	  struct cdrom_msf msf;

	  ioctl(fd, CDROMPLAYMSF, &msf);

	inputs:
		cdrom_msf structure, describing a segment of music to play

	outputs:	none

	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.

	notes:
	  MSF stands for minutes-seconds-frames
	  LBA stands for logical block address
		- MSF stands for minutes-seconds-frames
		- LBA stands for logical block address
		- Segment is described as start and end times, where each time
		  is described as minutes:seconds:frames.
		  A frame is 1/75 of a second.

	  Segment is described as start and end times, where each time
	  is described as minutes:seconds:frames.  A frame is 1/75 of
	  a second.

CDROMPLAYTRKIND
	Play Audio Track/index

CDROMPLAYTRKIND			Play Audio Track/index (struct cdrom_ti)
	(struct cdrom_ti)

	usage:

	usage::

	  struct cdrom_ti ti;

	  ioctl(fd, CDROMPLAYTRKIND, &ti);

	inputs:
		cdrom_ti structure, describing a segment of music to play

	outputs:	none

	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.

	notes:
	  Segment is described as start and end times, where each time
		- Segment is described as start and end times, where each time
		  is described as a track and an index.



CDROMREADTOCHDR			Read TOC header (struct cdrom_tochdr)
CDROMREADTOCHDR
	Read TOC header

	usage:
	(struct cdrom_tochdr)


	usage::

	  cdrom_tochdr header;

	  ioctl(fd, CDROMREADTOCHDR, &header);

	inputs:
		cdrom_tochdr structure


	outputs:
		cdrom_tochdr structure


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.



CDROMREADTOCENTRY		Read TOC entry (struct cdrom_tocentry)
CDROMREADTOCENTRY
	Read TOC entry

	(struct cdrom_tocentry)


	usage:
	usage::

	  struct cdrom_tocentry entry;

	  ioctl(fd, CDROMREADTOCENTRY, &entry);

	inputs:
		cdrom_tocentry structure


	outputs:
		cdrom_tocentry structure


	error return:
	  ENOSYS	cd drive not audio-capable.
	  EINVAL	entry.cdte_format not CDROM_MSF or CDROM_LBA
	  EINVAL	requested track out of bounds
	  EIO		I/O error reading TOC
	  - ENOSYS	cd drive not audio-capable.
	  - EINVAL	entry.cdte_format not CDROM_MSF or CDROM_LBA
	  - EINVAL	requested track out of bounds
	  - EIO		I/O error reading TOC

	notes:
	  TOC stands for Table Of Contents
	  MSF stands for minutes-seconds-frames
	  LBA stands for logical block address
		- TOC stands for Table Of Contents
		- MSF stands for minutes-seconds-frames
		- LBA stands for logical block address



CDROMSTOP			Stop the cdrom drive
CDROMSTOP
	Stop the cdrom drive

	usage:

	usage::

	  ioctl(fd, CDROMSTOP, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.

	notes:
	  Exact interpretation of this ioctl depends on the device,
	  - Exact interpretation of this ioctl depends on the device,
	    but most seem to spin the drive down.


CDROMSTART			Start the cdrom drive
CDROMSTART
	Start the cdrom drive


	usage:
	usage::

	  ioctl(fd, CDROMSTART, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.

	notes:
	  Exact interpretation of this ioctl depends on the device,
	  - Exact interpretation of this ioctl depends on the device,
	    but most seem to spin the drive up and/or close the tray.
	    Other devices ignore the ioctl completely.


CDROMEJECT			Ejects the cdrom media
CDROMEJECT
	- Ejects the cdrom media

	usage:

	usage::

	  ioctl(fd, CDROMEJECT, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error returns:
	  ENOSYS	cd drive not capable of ejecting
	  EBUSY		other processes are accessing drive, or door is locked
	  - ENOSYS	cd drive not capable of ejecting
	  - EBUSY	other processes are accessing drive, or door is locked

	notes:
	  See CDROM_LOCKDOOR, below.
		- See CDROM_LOCKDOOR, below.



CDROMCLOSETRAY			pendant of CDROMEJECT

	usage:
CDROMCLOSETRAY
	pendant of CDROMEJECT


	usage::

	  ioctl(fd, CDROMCLOSETRAY, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error returns:
	  ENOSYS	cd drive not capable of closing the tray
	  EBUSY		other processes are accessing drive, or door is locked
	  - ENOSYS	cd drive not capable of closing the tray
	  - EBUSY	other processes are accessing drive, or door is locked

	notes:
	  See CDROM_LOCKDOOR, below.
		- See CDROM_LOCKDOOR, below.



CDROMVOLCTRL			Control output volume (struct cdrom_volctrl)

	usage:
CDROMVOLCTRL
	Control output volume (struct cdrom_volctrl)


	usage::

	  struct cdrom_volctrl volume;

	  ioctl(fd, CDROMVOLCTRL, &volume);

	inputs:
		cdrom_volctrl structure containing volumes for up to 4
		channels.

	outputs:	none
	outputs:
		none


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.



CDROMVOLREAD			Get the drive's volume setting
CDROMVOLREAD
	Get the drive's volume setting

	(struct cdrom_volctrl)

	usage:

	usage::

	  struct cdrom_volctrl volume;

	  ioctl(fd, CDROMVOLREAD, &volume);

	inputs:		none
	inputs:
		none


	outputs:
		The current volume settings.


	error return:
	  ENOSYS	cd drive not audio-capable.
	  - ENOSYS	cd drive not audio-capable.



CDROMSUBCHNL			Read subchannel data (struct cdrom_subchnl)
CDROMSUBCHNL
	Read subchannel data

	(struct cdrom_subchnl)


	usage:
	usage::

	  struct cdrom_subchnl q;

	  ioctl(fd, CDROMSUBCHNL, &q);

	inputs:
		cdrom_subchnl structure


	outputs:
		cdrom_subchnl structure


	error return:
	  ENOSYS	cd drive not audio-capable.
	  EINVAL	format not CDROM_MSF or CDROM_LBA
	  - ENOSYS	cd drive not audio-capable.
	  - EINVAL	format not CDROM_MSF or CDROM_LBA

	notes:
	  Format is converted to CDROM_MSF or CDROM_LBA
		- Format is converted to CDROM_MSF or CDROM_LBA
		  as per user request on return



CDROMREADRAW			read data in raw mode (2352 Bytes)
CDROMREADRAW
	read data in raw mode (2352 Bytes)

	(struct cdrom_read)

	usage:
	usage::

	  union {

	    struct cdrom_msf msf;		/* input */
	    char buffer[CD_FRAMESIZE_RAW];	/* return */
	  } arg;
@@ -358,29 +452,33 @@ CDROMREADRAW read data in raw mode (2352 Bytes)

	inputs:
		cdrom_msf structure indicating an address to read.

		Only the start values are significant.

	outputs:
		Data written to address provided by user.


	error return:
	  EINVAL	address less than 0, or msf less than 0:2:0
	  ENOMEM	out of memory
	  - EINVAL	address less than 0, or msf less than 0:2:0
	  - ENOMEM	out of memory

	notes:
	  As of 2.6.8.1, comments in <linux/cdrom.h> indicate that this
		- As of 2.6.8.1, comments in <linux/cdrom.h> indicate that this
		  ioctl accepts a cdrom_read structure, but actual source code
		  reads a cdrom_msf structure and writes a buffer of data to
		  the same address.

	  MSF values are converted to LBA values via this formula:
		- MSF values are converted to LBA values via this formula::

		    lba = (((m * CD_SECS) + s) * CD_FRAMES + f) - CD_MSF_OFFSET;




CDROMREADMODE1			Read CDROM mode 1 data (2048 Bytes)
CDROMREADMODE1
	Read CDROM mode 1 data (2048 Bytes)

	(struct cdrom_read)

	notes:
@@ -389,7 +487,9 @@ CDROMREADMODE1 Read CDROM mode 1 data (2048 Bytes)



CDROMREADMODE2			Read CDROM mode 2 data (2336 Bytes)
CDROMREADMODE2
	Read CDROM mode 2 data (2336 Bytes)

	(struct cdrom_read)

	notes:
@@ -398,11 +498,13 @@ CDROMREADMODE2 Read CDROM mode 2 data (2336 Bytes)



CDROMREADAUDIO			(struct cdrom_read_audio)
CDROMREADAUDIO
	(struct cdrom_read_audio)

	usage:
	usage::

	  struct cdrom_read_audio ra;

	  ioctl(fd, CDROMREADAUDIO, &ra);

	inputs:
@@ -412,42 +514,53 @@ CDROMREADAUDIO (struct cdrom_read_audio)
	outputs:
		audio data, returned to buffer indicated by ra


	error return:
	  EINVAL	format not CDROM_MSF or CDROM_LBA
	  EINVAL	nframes not in range [1 75]
	  ENXIO		drive has no queue (probably means invalid fd)
	  ENOMEM	out of memory
	  - EINVAL	format not CDROM_MSF or CDROM_LBA
	  - EINVAL	nframes not in range [1 75]
	  - ENXIO	drive has no queue (probably means invalid fd)
	  - ENOMEM	out of memory


CDROMEJECT_SW			enable(1)/disable(0) auto-ejecting
CDROMEJECT_SW
	enable(1)/disable(0) auto-ejecting

	usage:

	usage::

	  int val;

	  ioctl(fd, CDROMEJECT_SW, val);

	inputs:
		Flag specifying auto-eject flag.

	outputs:	none

	outputs:
		none


	error return:
	  ENOSYS	Drive is not capable of ejecting.
	  EBUSY		Door is locked
	  - ENOSYS	Drive is not capable of ejecting.
	  - EBUSY	Door is locked




CDROMMULTISESSION		Obtain the start-of-last-session
				  address of multi session disks
CDROMMULTISESSION
	Obtain the start-of-last-session address of multi session disks

	(struct cdrom_multisession)
	usage:

	usage::

	  struct cdrom_multisession ms_info;

	  ioctl(fd, CDROMMULTISESSION, &ms_info);

	inputs:
		cdrom_multisession structure containing desired

	  format.

	outputs:
@@ -455,27 +568,35 @@ CDROMMULTISESSION Obtain the start-of-last-session
		information.

	error return:
	  EINVAL	format not CDROM_MSF or CDROM_LBA
	  - EINVAL	format not CDROM_MSF or CDROM_LBA


CDROM_GET_MCN			Obtain the "Universal Product Code"
				   if available (struct cdrom_mcn)
CDROM_GET_MCN
	Obtain the "Universal Product Code"
	if available

	(struct cdrom_mcn)

	usage:

	usage::

	  struct cdrom_mcn mcn;

	  ioctl(fd, CDROM_GET_MCN, &mcn);

	inputs:		none
	inputs:
		none


	outputs:
		Universal Product Code


	error return:
	  ENOSYS	Drive is not capable of reading MCN data.
	  - ENOSYS	Drive is not capable of reading MCN data.

	notes:
	  Source code comments state:
		- Source code comments state::

		    The following function is implemented, although very few
		    audio discs give Universal Product Code information, which
@@ -486,89 +607,123 @@ CDROM_GET_MCN Obtain the "Universal Product Code"



CDROM_GET_UPC			CDROM_GET_MCN  (deprecated)
CDROM_GET_UPC
	CDROM_GET_MCN  (deprecated)


	Not implemented, as of 2.6.8.1



CDROMRESET			hard-reset the drive
CDROMRESET
	hard-reset the drive


	usage:
	usage::

	  ioctl(fd, CDROMRESET, 0);

	inputs:		none

	outputs:	none
	inputs:
		none


	outputs:
		none


	error return:
	  EACCES	Access denied:  requires CAP_SYS_ADMIN
	  ENOSYS	Drive is not capable of resetting.
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - ENOSYS	Drive is not capable of resetting.




CDROMREADCOOKED			read data in cooked mode
CDROMREADCOOKED
	read data in cooked mode


	usage:
	usage::

	  u8 buffer[CD_FRAMESIZE]

	  ioctl(fd, CDROMREADCOOKED, buffer);

	inputs:		none
	inputs:
		none


	outputs:
		2048 bytes of data, "cooked" mode.


	notes:
		Not implemented on all drives.




CDROMREADALL			read all 2646 bytes

CDROMREADALL
	read all 2646 bytes


	Same as CDROMREADCOOKED, but reads 2646 bytes.



CDROMSEEK			seek msf address
CDROMSEEK
	seek msf address

	usage:

	usage::

	  struct cdrom_msf msf;

	  ioctl(fd, CDROMSEEK, &msf);

	inputs:
		MSF address to seek to.

	outputs:	none

	outputs:
		none


CDROMPLAYBLK			scsi-cd only, (struct cdrom_blk)

	usage:

CDROMPLAYBLK
	scsi-cd only

	(struct cdrom_blk)


	usage::

	  struct cdrom_blk blk;

	  ioctl(fd, CDROMPLAYBLK, &blk);

	inputs:
		Region to play

	outputs:	none

	outputs:
		none



CDROMGETSPINDOWN

	usage:
CDROMGETSPINDOWN
	usage::

	  char spindown;

	  ioctl(fd, CDROMGETSPINDOWN, &spindown);

	inputs:		none
	inputs:
		none


	outputs:
		The value of the current 4-bit spindown value.
@@ -576,162 +731,207 @@ CDROMGETSPINDOWN



CDROMSETSPINDOWN

	usage:
CDROMSETSPINDOWN
	usage::

	  char spindown

	  ioctl(fd, CDROMSETSPINDOWN, &spindown);

	inputs:
		4-bit value used to control spindown (TODO: more detail here)

	outputs:	none

	outputs:
		none




CDROM_SET_OPTIONS		Set behavior options

	usage:

CDROM_SET_OPTIONS
	Set behavior options


	usage::

	  int options;

	  ioctl(fd, CDROM_SET_OPTIONS, options);

	inputs:
		New values for drive options.  The logical 'or' of:

	    ==============      ==================================
	    CDO_AUTO_CLOSE	close tray on first open(2)
	    CDO_AUTO_EJECT	open tray on last release
	    CDO_USE_FFLAGS	use O_NONBLOCK information on open
	    CDO_LOCK		lock tray on open files
	    CDO_CHECK_TYPE	check type on open for data
	    ==============      ==================================

	outputs:
		Returns the resulting options settings in the
		ioctl return value.  Returns -1 on error.

	error return:
	  ENOSYS	selected option(s) not supported by drive.
	  - ENOSYS	selected option(s) not supported by drive.




CDROM_CLEAR_OPTIONS		Clear behavior options
CDROM_CLEAR_OPTIONS
	Clear behavior options


	Same as CDROM_SET_OPTIONS, except that selected options are
	turned off.



CDROM_SELECT_SPEED		Set the CD-ROM speed
CDROM_SELECT_SPEED
	Set the CD-ROM speed


	usage:
	usage::

	  int speed;

	  ioctl(fd, CDROM_SELECT_SPEED, speed);

	inputs:
		New drive speed.

	outputs:	none

	outputs:
		none


	error return:
	  ENOSYS	speed selection not supported by drive.
	  - ENOSYS	speed selection not supported by drive.



CDROM_SELECT_DISC		Select disc (for juke-boxes)
CDROM_SELECT_DISC
	Select disc (for juke-boxes)


	usage:
	usage::

	  int disk;

	  ioctl(fd, CDROM_SELECT_DISC, disk);

	inputs:
		Disk to load into drive.

	outputs:	none

	outputs:
		none


	error return:
	  EINVAL	Disk number beyond capacity of drive
	  - EINVAL	Disk number beyond capacity of drive



CDROM_MEDIA_CHANGED		Check is media changed
CDROM_MEDIA_CHANGED
	Check is media changed


	usage:
	usage::

	  int slot;

	  ioctl(fd, CDROM_MEDIA_CHANGED, slot);

	inputs:
		Slot number to be tested, always zero except for jukeboxes.

		May also be special values CDSL_NONE or CDSL_CURRENT

	outputs:
		Ioctl return value is 0 or 1 depending on whether the media

	  has been changed, or -1 on error.

	error returns:
	  ENOSYS	Drive can't detect media change
	  EINVAL	Slot number beyond capacity of drive
	  ENOMEM	Out of memory
	  - ENOSYS	Drive can't detect media change
	  - EINVAL	Slot number beyond capacity of drive
	  - ENOMEM	Out of memory



CDROM_DRIVE_STATUS		Get tray position, etc.
CDROM_DRIVE_STATUS
	Get tray position, etc.

	usage:

	usage::

	  int slot;

	  ioctl(fd, CDROM_DRIVE_STATUS, slot);

	inputs:
		Slot number to be tested, always zero except for jukeboxes.

		May also be special values CDSL_NONE or CDSL_CURRENT

	outputs:
		Ioctl return value will be one of the following values

	  from <linux/cdrom.h>:

	    =================== ==========================
	    CDS_NO_INFO		Information not available.
	    CDS_NO_DISC
	    CDS_TRAY_OPEN
	    CDS_DRIVE_NOT_READY
	    CDS_DISC_OK
	    -1			error
	    =================== ==========================

	error returns:
	  ENOSYS	Drive can't detect drive status
	  EINVAL	Slot number beyond capacity of drive
	  ENOMEM	Out of memory
	  - ENOSYS	Drive can't detect drive status
	  - EINVAL	Slot number beyond capacity of drive
	  - ENOMEM	Out of memory




CDROM_DISC_STATUS		Get disc type, etc.
CDROM_DISC_STATUS
	Get disc type, etc.


	usage:
	usage::

	  ioctl(fd, CDROM_DISC_STATUS, 0);

	inputs:		none

	inputs:
		none


	outputs:
		Ioctl return value will be one of the following values

	  from <linux/cdrom.h>:
	    CDS_NO_INFO
	    CDS_AUDIO
	    CDS_MIXED
	    CDS_XA_2_2
	    CDS_XA_2_1
	    CDS_DATA_1

	error returns:	none at present
	    - CDS_NO_INFO
	    - CDS_AUDIO
	    - CDS_MIXED
	    - CDS_XA_2_2
	    - CDS_XA_2_1
	    - CDS_DATA_1

	error returns:
		none at present

	notes:
	  Source code comments state:
	    - Source code comments state::


		Ok, this is where problems start.  The current interface for
		the CDROM_DISC_STATUS ioctl is flawed.  It makes the false
@@ -755,37 +955,53 @@ CDROM_DISC_STATUS Get disc type, etc.



CDROM_CHANGER_NSLOTS		Get number of slots
CDROM_CHANGER_NSLOTS
	Get number of slots

	usage:

	usage::

	  ioctl(fd, CDROM_CHANGER_NSLOTS, 0);

	inputs:		none

	inputs:
		none


	outputs:
		The ioctl return value will be the number of slots in a
		CD changer.  Typically 1 for non-multi-disk devices.

	error returns:	none
	error returns:
		none



CDROM_LOCKDOOR			lock or unlock door
CDROM_LOCKDOOR
	lock or unlock door

	usage:

	usage::

	  int lock;

	  ioctl(fd, CDROM_LOCKDOOR, lock);

	inputs:
		Door lock flag, 1=lock, 0=unlock

	outputs:	none

	outputs:
		none


	error returns:
	  EDRIVE_CANT_DO_THIS	Door lock function not supported.
	  EBUSY			Attempt to unlock when multiple users
	  - EDRIVE_CANT_DO_THIS

				Door lock function not supported.
	  - EBUSY

				Attempt to unlock when multiple users
				have the drive open and not CAP_SYS_ADMIN

	notes:
@@ -798,31 +1014,41 @@ CDROM_LOCKDOOR lock or unlock door



CDROM_DEBUG			Turn debug messages on/off
CDROM_DEBUG
	Turn debug messages on/off

	usage:

	usage::

	  int debug;

	  ioctl(fd, CDROM_DEBUG, debug);

	inputs:
		Cdrom debug flag, 0=disable, 1=enable


	outputs:
		The ioctl return value will be the new debug flag.


	error return:
	  EACCES	Access denied:  requires CAP_SYS_ADMIN
	  - EACCES	Access denied:  requires CAP_SYS_ADMIN



CDROM_GET_CAPABILITY		get capabilities
CDROM_GET_CAPABILITY
	get capabilities


	usage:
	usage::

	  ioctl(fd, CDROM_GET_CAPABILITY, 0);

	inputs:		none

	inputs:
		none


	outputs:
		The ioctl return value is the current device capability
@@ -830,37 +1056,45 @@ CDROM_GET_CAPABILITY get capabilities



CDROMAUDIOBUFSIZ		set the audio buffer size
CDROMAUDIOBUFSIZ
	set the audio buffer size

	usage:

	usage::

	  int arg;

	  ioctl(fd, CDROMAUDIOBUFSIZ, val);

	inputs:
		New audio buffer size


	outputs:
		The ioctl return value is the new audio buffer size, or -1
		on error.

	error return:
	  ENOSYS	Not supported by this driver.
	  - ENOSYS	Not supported by this driver.

	notes:
		Not supported by all drivers.




DVD_READ_STRUCT			Read structure

	usage:
	usage::

	  dvd_struct s;

	  ioctl(fd, DVD_READ_STRUCT, &s);

	inputs:
		dvd_struct structure, containing:

	    =================== ==========================================
	    type		specifies the information desired, one of
				DVD_STRUCT_PHYSICAL, DVD_STRUCT_COPYRIGHT,
				DVD_STRUCT_DISCKEY, DVD_STRUCT_BCA,
@@ -868,18 +1102,22 @@ DVD_READ_STRUCT Read structure
	    physical.layer_num	desired layer, indexed from 0
	    copyright.layer_num	desired layer, indexed from 0
	    disckey.agid
	    =================== ==========================================

	outputs:
		dvd_struct structure, containing:

	    =================== ================================
	    physical		for type == DVD_STRUCT_PHYSICAL
	    copyright		for type == DVD_STRUCT_COPYRIGHT
	    disckey.value	for type == DVD_STRUCT_DISCKEY
	    bca.{len,value}	for type == DVD_STRUCT_BCA
	    manufact.{len,valu}	for type == DVD_STRUCT_MANUFACT
	    =================== ================================

	error returns:
	  EINVAL	physical.layer_num exceeds number of layers
	  EIO		Received invalid response from drive
	  - EINVAL	physical.layer_num exceeds number of layers
	  - EIO		Received invalid response from drive



@@ -891,75 +1129,103 @@ DVD_WRITE_STRUCT Write structure

DVD_AUTH			Authentication

	usage:
	usage::

	  dvd_authinfo ai;

	  ioctl(fd, DVD_AUTH, &ai);

	inputs:
		dvd_authinfo structure.  See <linux/cdrom.h>


	outputs:
		dvd_authinfo structure.


	error return:
	  ENOTTY	ai.type not recognized.
	  - ENOTTY	ai.type not recognized.



CDROM_SEND_PACKET		send a packet to the drive
CDROM_SEND_PACKET
	send a packet to the drive


	usage:
	usage::

	  struct cdrom_generic_command cgc;

	  ioctl(fd, CDROM_SEND_PACKET, &cgc);

	inputs:
		cdrom_generic_command structure containing the packet to send.

	outputs:	none

	outputs:
		none

	  cdrom_generic_command structure containing results.

	error return:
	  EIO		command failed.
	  EPERM		Operation not permitted, either because a
	  - EIO

			command failed.
	  - EPERM

			Operation not permitted, either because a
			write command was attempted on a drive which
			is opened read-only, or because the command
			requires CAP_SYS_RAWIO
	  EINVAL	cgc.data_direction not set
	  - EINVAL

			cgc.data_direction not set


CDROM_NEXT_WRITABLE		get next writable block

	usage:
CDROM_NEXT_WRITABLE
	get next writable block


	usage::

	  long next;

	  ioctl(fd, CDROM_NEXT_WRITABLE, &next);

	inputs:		none
	inputs:
		none


	outputs:
		The next writable block.


	notes:
		If the device does not support this ioctl directly, the

	  ioctl will return CDROM_LAST_WRITTEN + 7.



CDROM_LAST_WRITTEN		get last block written on disc
CDROM_LAST_WRITTEN
	get last block written on disc


	usage:
	usage::

	  long last;

	  ioctl(fd, CDROM_LAST_WRITTEN, &last);

	inputs:		none
	inputs:
		none


	outputs:
		The last block written on disc


	notes:
		If the device does not support this ioctl directly, the
		result is derived from the disc's table of contents.  If the
+553 −282

File changed and moved.

Preview size limit exceeded, changes collapsed.

+16 −0
Original line number Diff line number Diff line
:orphan:

======
IOCTLs
======

.. toctree::
   :maxdepth: 1

   ioctl-number

   botching-up-ioctls
   ioctl-decoding

   cdrom
   hdio
+10 −3
Original line number Diff line number Diff line
==============================
Decoding an IOCTL Magic Number
==============================

To decode a hex IOCTL code:

Most architectures use this generic format, but check
include/ARCH/ioctl.h for specifics, e.g. powerpc
uses 3 bits to encode read/write and 13 bits for size.

 ====== ==================================
 bits   meaning
 ====== ==================================
 31-30	00 - no parameters: uses _IO macro
	10 - read: _IOR
	01 - write: _IOW
@@ -16,9 +22,10 @@ uses 3 bits to encode read/write and 13 bits for size.
	unique to each driver

 7-0	function #
 ====== ==================================


So for example 0x82187201 is a read with arg length of 0x218,
character 'r' function 1. Grepping the source reveals this is:
character 'r' function 1. Grepping the source reveals this is::

	#define VFAT_IOCTL_READDIR_BOTH         _IOR('r', 1, struct dirent [2])
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