Kernel-2.6.32-573.12.1.el6_cdro

    Summary of CDROM ioctl calls.
    ============================

    Edward A. Falk <efalk@google.com>

    November, 2004

This document attempts to describe the ioctl(2) calls supported by
the CDROM layer. These are by-and-large implemented (as of Linux 2.6)
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)
CDROMPLAYTRKIND        Play Audio Track/index (struct cdrom_ti)
CDROMREADTOCHDR        Read TOC header (struct cdrom_tochdr)
CDROMREADTOCENTRY    Read TOC entry (struct cdrom_tocentry)
CDROMSTOP        Stop the cdrom drive
CDROMSTART        Start the cdrom drive
CDROMEJECT        Ejects the cdrom media
CDROMVOLCTRL        Control output volume (struct cdrom_volctrl)
CDROMSUBCHNL        Read subchannel data (struct cdrom_subchnl)
CDROMREADMODE2        Read CDROM mode 2 data (2336 Bytes)
                   (struct cdrom_read)
CDROMREADMODE1        Read CDROM mode 1 data (2048 Bytes)
                   (struct cdrom_read)
CDROMREADAUDIO        (struct cdrom_read_audio)
CDROMEJECT_SW        enable(1)/disable(0) auto-ejecting
CDROMMULTISESSION    Obtain the start-of-last-session
              address of multi session disks
              (struct cdrom_multisession)
CDROM_GET_MCN        Obtain the "Universal Product Code"
               if available (struct cdrom_mcn)
CDROM_GET_UPC        Deprecated, use CDROM_GET_MCN instead.
CDROMRESET        hard-reset the drive
CDROMVOLREAD        Get the drive's volume setting
                  (struct cdrom_volctrl)
CDROMREADRAW        read data in raw mode (2352 Bytes)
                   (struct cdrom_read)
CDROMREADCOOKED        read data in cooked mode
CDROMSEEK        seek msf address
CDROMPLAYBLK        scsi-cd only, (struct cdrom_blk)
CDROMREADALL        read all 2646 bytes
CDROMGETSPINDOWN    return 4-bit spindown value
CDROMSETSPINDOWN    set 4-bit spindown value
CDROMCLOSETRAY        pendant of CDROMEJECT
CDROM_SET_OPTIONS    Set behavior options
CDROM_CLEAR_OPTIONS    Clear behavior options
CDROM_SELECT_SPEED    Set the CD-ROM speed
CDROM_SELECT_DISC    Select disc (for juke-boxes)
CDROM_MEDIA_CHANGED    Check is media changed
CDROM_DRIVE_STATUS    Get tray position, etc.
CDROM_DISC_STATUS    Get disc type, etc.
CDROM_CHANGER_NSLOTS    Get number of slots
CDROM_LOCKDOOR        lock or unlock door
CDROM_DEBUG        Turn debug messages on/off
CDROM_GET_CAPABILITY    get capabilities
CDROMAUDIOBUFSIZ    set the audio buffer size
DVD_READ_STRUCT        Read structure
DVD_WRITE_STRUCT    Write structure
DVD_AUTH        Authentication
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:

Unless otherwise specified, all ioctl calls return 0 on success
and -1 with errno set to an appropriate value on error.  (Some
ioctls return non-negative data values.)

Unless otherwise specified, all ioctl calls return -1 and set
errno to EFAULT on a failed attempt to copy data to or from user
address space.

Individual drivers may return error codes not listed here.

Unless otherwise specified, all data structures and constants
are defined in <linux/cdrom.h>

CDROMPAUSE Pause Audio Operation

usage:

  ioctl(fd, CDROMPAUSE, 0);

inputs:        none

outputs:    none

error return:
  ENOSYS    cd drive not audio-capable.

CDROMRESUME Resume paused Audio Operation

usage:

  ioctl(fd, CDROMRESUME, 0);

inputs:        none

outputs:    none

error return:
  ENOSYS    cd drive not audio-capable.

CDROMPLAYMSF Play Audio MSF (struct cdrom_msf)

usage:

  struct cdrom_msf msf;
  ioctl(fd, CDROMPLAYMSF, &msf);

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

outputs:    none

error return:
  ENOSYS    cd drive not audio-capable.

notes:
  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.

CDROMPLAYTRKIND Play Audio Track/index (struct cdrom_ti)

usage:

  struct cdrom_ti ti;
  ioctl(fd, CDROMPLAYTRKIND, &ti);

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

outputs:    none

error return:
  ENOSYS    cd drive not audio-capable.

notes:
  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)

usage:

  cdrom_tochdr header;
  ioctl(fd, CDROMREADTOCHDR, &header);

inputs:
  cdrom_tochdr structure

outputs:
  cdrom_tochdr structure

error return:
  ENOSYS    cd drive not audio-capable.

CDROMREADTOCENTRY Read TOC entry (struct cdrom_tocentry)

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

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

CDROMSTOP Stop the cdrom drive

usage:

  ioctl(fd, CDROMSTOP, 0);

inputs:        none

outputs:    none

error return:
  ENOSYS    cd drive not audio-capable.

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

CDROMSTART Start the cdrom drive

usage:

  ioctl(fd, CDROMSTART, 0);

inputs:        none

outputs:    none

error return:
  ENOSYS    cd drive not audio-capable.

notes:
  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

usage:

  ioctl(fd, CDROMEJECT, 0);

inputs:        none

outputs:    none

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

notes:
  See CDROM_LOCKDOOR, below.

CDROMCLOSETRAY pendant of CDROMEJECT

usage:

  ioctl(fd, CDROMCLOSETRAY, 0);

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

notes:
  See CDROM_LOCKDOOR, below.

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

error return:
  ENOSYS    cd drive not audio-capable.

CDROMVOLREAD Get the drive’s volume setting
(struct cdrom_volctrl)

usage:

  struct cdrom_volctrl volume;
  ioctl(fd, CDROMVOLREAD, &volume);

inputs:        none

outputs:
  The current volume settings.

error return:
  ENOSYS    cd drive not audio-capable.

CDROMSUBCHNL Read subchannel data (struct cdrom_subchnl)

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

notes:
  Format is converted to CDROM_MSF on return

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

usage:

  union {
    struct cdrom_msf msf;        /* input */
    char buffer[CD_FRAMESIZE_RAW];    /* return */
  } arg;
  ioctl(fd, CDROMREADRAW, &arg);

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

notes:
  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:

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

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

notes:
  Identical to CDROMREADRAW except that block size is
  CD_FRAMESIZE (2048) bytes

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

notes:
  Identical to CDROMREADRAW except that block size is
  CD_FRAMESIZE_RAW0 (2336) bytes

CDROMREADAUDIO (struct cdrom_read_audio)

usage:

  struct cdrom_read_audio ra;
  ioctl(fd, CDROMREADAUDIO, &ra);

inputs:
  cdrom_read_audio structure containing read start
  point and length

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

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

usage:

  int val;
  ioctl(fd, CDROMEJECT_SW, val);

inputs:
  Flag specifying auto-eject flag.

outputs:    none

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

CDROMMULTISESSION Obtain the start-of-last-session
address of multi session disks
(struct cdrom_multisession)
usage:

  struct cdrom_multisession ms_info;
  ioctl(fd, CDROMMULTISESSION, &ms_info);

inputs:
  cdrom_multisession structure containing desired
  format.

outputs:
  cdrom_multisession structure is filled with last_session
  information.

error return:
  EINVAL    format not CDROM_MSF or CDROM_LBA

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

usage:

  struct cdrom_mcn mcn;
  ioctl(fd, CDROM_GET_MCN, &mcn);

inputs:        none

outputs:
  Universal Product Code

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

notes:
  Source code comments state:

    The following function is implemented, although very few
    audio discs give Universal Product Code information, which
    should just be the Medium Catalog Number on the box.  Note,
    that the way the code is written on the CD is /not/ uniform
    across all discs!

CDROM_GET_UPC CDROM_GET_MCN (deprecated)

Not implemented, as of 2.6.8.1

CDROMRESET hard-reset the drive

usage:

  ioctl(fd, CDROMRESET, 0);

inputs:        none

outputs:    none

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

CDROMREADCOOKED read data in cooked mode

usage:

  u8 buffer[CD_FRAMESIZE]
  ioctl(fd, CDROMREADCOOKED, buffer);

inputs:        none

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

notes:
  Not implemented on all drives.

CDROMREADALL read all 2646 bytes

Same as CDROMREADCOOKED, but reads 2646 bytes.

CDROMSEEK seek msf address

usage:

  struct cdrom_msf msf;
  ioctl(fd, CDROMSEEK, &msf);

inputs:
  MSF address to seek to.

outputs:    none

CDROMPLAYBLK scsi-cd only, (struct cdrom_blk)

usage:

  struct cdrom_blk blk;
  ioctl(fd, CDROMPLAYBLK, &blk);

inputs:
  Region to play

outputs:    none

CDROMGETSPINDOWN

usage:

  char spindown;
  ioctl(fd, CDROMGETSPINDOWN, &spindown);

inputs:        none

outputs:
  The value of the current 4-bit spindown value.

CDROMSETSPINDOWN

usage:

  char spindown
  ioctl(fd, CDROMSETSPINDOWN, &spindown);

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

outputs:    none

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.

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

usage:

  int speed;
  ioctl(fd, CDROM_SELECT_SPEED, speed);

inputs:
  New drive speed.

outputs:    none

error return:
  ENOSYS    speed selection not supported by drive.

CDROM_SELECT_DISC Select disc (for juke-boxes)

usage:

  int disk;
  ioctl(fd, CDROM_SELECT_DISC, disk);

inputs:
  Disk to load into drive.

outputs:    none

error return:
  EINVAL    Disk number beyond capacity of drive

CDROM_MEDIA_CHANGED Check is media changed

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

CDROM_DRIVE_STATUS Get tray position, etc.

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

CDROM_DISC_STATUS Get disc type, etc.

usage:

  ioctl(fd, CDROM_DISC_STATUS, 0);

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

notes:
  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
    assumption that CDs are all CDS_DATA_1 or all CDS_AUDIO, etc.
    Unfortunately, while this is often the case, it is also
    very common for CDs to have some tracks with data, and some
    tracks with audio.    Just because I feel like it, I declare
    the following to be the best way to cope.  If the CD has
    ANY data tracks on it, it will be returned as a data CD.
    If it has any XA tracks, I will return it as that.    Now I
    could simplify this interface by combining these returns with
    the above, but this more clearly demonstrates the problem
    with the current interface.  Too bad this wasn't designed
    to use bitmasks...           -Erik

    Well, now we have the option CDS_MIXED: a mixed-type CD.
    User level programmers might feel the ioctl is not very
    useful.
        ---david

CDROM_CHANGER_NSLOTS Get number of slots

usage:

  ioctl(fd, CDROM_CHANGER_NSLOTS, 0);

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

CDROM_LOCKDOOR lock or unlock door

usage:

  int lock;
  ioctl(fd, CDROM_LOCKDOOR, lock);

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

outputs:    none

error returns:
  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:
  As of 2.6.8.1, the lock flag is a global lock, meaning that
  all CD drives will be locked or unlocked together.  This is
  probably a bug.

  The EDRIVE_CANT_DO_THIS value is defined in <linux/cdrom.h>
  and is currently (2.6.8.1) the same as EOPNOTSUPP

CDROM_DEBUG Turn debug messages on/off

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

CDROM_GET_CAPABILITY get capabilities

usage:

  ioctl(fd, CDROM_GET_CAPABILITY, 0);

inputs:        none

outputs:
  The ioctl return value is the current device capability
  flags.  See CDC_CLOSE_TRAY, CDC_OPEN_TRAY, etc.

CDROMAUDIOBUFSIZ set the audio buffer size

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.

notes:
  Not supported by all drivers.

DVD_READ_STRUCT Read structure

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,
            DVD_STRUCT_MANUFACT
    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

DVD_WRITE_STRUCT Write structure

Not implemented, as of 2.6.8.1

DVD_AUTH Authentication

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.

CDROM_SEND_PACKET send a packet to the drive

usage:

  struct cdrom_generic_command cgc;
  ioctl(fd, CDROM_SEND_PACKET, &cgc);

inputs:
  cdrom_generic_command structure containing the packet to send.

outputs:    none
  cdrom_generic_command structure containing results.

error return:
  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

CDROM_NEXT_WRITABLE get next writable block

usage:

  long next;
  ioctl(fd, CDROM_NEXT_WRITABLE, &next);

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

usage:

  long last;
  ioctl(fd, CDROM_LAST_WRITTEN, &last);

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
  table of contents can't be read, this ioctl returns an
  error.