ioctls that pass argument pointers to user space:

=======================	=======================================
HDIO_GETGEO		get device geometry
HDIO_GET_32BIT		get current io_32bit setting
HDIO_GET_IDENTITY	get IDE identification info
HDIO_DRIVE_TASKFILE	execute raw taskfile
HDIO_DRIVE_TASK		execute task and special drive command
HDIO_DRIVE_CMD		execute a special drive command
=======================	=======================================

ioctls that pass non-pointer values:

=======================	=======================================
HDIO_SET_32BIT		change io_32bit flags
=======================	=======================================

Unless otherwise specified, all ioctl calls return 0 on success
and -1 with errno set to an appropriate value on error.

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.

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

usage::

  struct hd_geometry geom;

  ioctl(fd, HDIO_GETGEO, &geom);


inputs:
	none



outputs:
	hd_geometry structure containing:


    =========	==================================
    heads	number of heads
    sectors	number of sectors/track
    cylinders	number of cylinders, mod 65536
    start	starting sector of this partition.
    =========	==================================


error returns:
  - EINVAL

		if the device is not a disk drive or floppy drive,
		or if the user passes a null pointer


notes:
	Not particularly useful with modern disk drives, whose geometry
	is a polite fiction anyway.  Modern drives are addressed
	purely by sector number nowadays (lba addressing), and the
	drive geometry is an abstraction which is actually subject
	to change.  Currently (as of Nov 2004), the geometry values
	are the "bios" values -- presumably the values the drive had
	when Linux first booted.

	In addition, the cylinders field of the hd_geometry is an
	unsigned short, meaning that on most architectures, this
	ioctl will not return a meaningful value on drives with more
	than 65535 tracks.

	The start field is unsigned long, meaning that it will not
	contain a meaningful value for disks over 219 Gb in size.

usage::

  unsigned char identity[512];

  ioctl(fd, HDIO_GET_IDENTITY, identity);

inputs:
	none



outputs:
	ATA drive identity information.  For full description, see
	the IDENTIFY DEVICE and IDENTIFY PACKET DEVICE commands in
	the ATA specification.

error returns:
  - EINVAL	Called on a partition instead of the whole disk device
  - ENOMSG	IDENTIFY DEVICE information not available

notes:
	Returns information that was obtained when the drive was
	probed.  Some of this information is subject to change, and
	this ioctl does not re-probe the drive to update the
	information.

	This information is also available from /proc/ide/hdX/identify

usage::

  long val;

  ioctl(fd, HDIO_GET_32BIT, &val);

inputs:
	none



outputs:
	The value of the current io_32bit setting



notes:
	0=16-bit, 1=32-bit, 2,3 = 32bit+sync

Note:
	If you don't have a copy of the ANSI ATA specification
	handy, you should probably ignore this ioctl.

- Execute an ATA disk command directly by writing the "taskfile"
  registers of the drive.  Requires ADMIN and RAWIO access
  privileges.

usage::

  struct {

    ide_task_request_t req_task;
    u8 outbuf[OUTPUT_SIZE];
    u8 inbuf[INPUT_SIZE];
  } task;
  memset(&task.req_task, 0, sizeof(task.req_task));
  task.req_task.out_size = sizeof(task.outbuf);
  task.req_task.in_size = sizeof(task.inbuf);
  ...
  ioctl(fd, HDIO_DRIVE_TASKFILE, &task);
  ...

inputs:

  (See below for details on memory area passed to ioctl.)

  ============	===================================================
  io_ports[8]	values to be written to taskfile registers
  hob_ports[8]	high-order bytes, for extended commands.
  out_flags	flags indicating which registers are valid
  in_flags	flags indicating which registers should be returned
  data_phase	see below
  req_cmd	command type to be executed
  out_size	size of output buffer
  outbuf	buffer of data to be transmitted to disk
  inbuf		buffer of data to be received from disk (see [1])
  ============	===================================================

outputs:

  ===========	====================================================
  io_ports[]	values returned in the taskfile registers
  hob_ports[]	high-order bytes, for extended commands.
  out_flags	flags indicating which registers are valid (see [2])
  in_flags	flags indicating which registers should be returned
  outbuf	buffer of data to be transmitted to disk (see [1])
  inbuf		buffer of data to be received from disk
  ===========	====================================================

error returns:
  - EACCES	CAP_SYS_ADMIN or CAP_SYS_RAWIO privilege not set.
  - ENOMSG	Device is not a disk drive.
  - ENOMEM	Unable to allocate memory for task
  - EFAULT	req_cmd == TASKFILE_IN_OUT (not implemented as of 2.6.8)
  - EPERM

		req_cmd == TASKFILE_MULTI_OUT and drive
		multi-count not yet set.
  - EIO		Drive failed the command.

notes:

  [1] READ THE FOLLOWING NOTES *CAREFULLY*.  THIS IOCTL IS
  FULL OF GOTCHAS.  Extreme caution should be used with using
  this ioctl.  A mistake can easily corrupt data or hang the
  system.

  [2] Both the input and output buffers are copied from the
  user and written back to the user, even when not used.

  [3] If one or more bits are set in out_flags and in_flags is
  zero, the following values are used for in_flags.all and
  written back into in_flags on completion.

   * IDE_TASKFILE_STD_IN_FLAGS | (IDE_HOB_STD_IN_FLAGS << 8)
     if LBA48 addressing is enabled for the drive
   * IDE_TASKFILE_STD_IN_FLAGS
     if CHS/LBA28

  The association between in_flags.all and each enable
  bitfield flips depending on endianness; fortunately, TASKFILE
  only uses inflags.b.data bit and ignores all other bits.
  The end result is that, on any endian machines, it has no
  effect other than modifying in_flags on completion.

  [4] The default value of SELECT is (0xa0|DEV_bit|LBA_bit)
  except for four drives per port chipsets.  For four drives
  per port chipsets, it's (0xa0|DEV_bit|LBA_bit) for the first
  pair and (0x80|DEV_bit|LBA_bit) for the second pair.

  [5] The argument to the ioctl is a pointer to a region of
  memory containing a ide_task_request_t structure, followed
  by an optional buffer of data to be transmitted to the
  drive, followed by an optional buffer to receive data from
  the drive.

  Command is passed to the disk drive via the ide_task_request_t
  structure, which contains these fields:

    ============	===============================================
    io_ports[8]		values for the taskfile registers
    hob_ports[8]	high-order bytes, for extended commands
    out_flags		flags indicating which entries in the
			io_ports[] and hob_ports[] arrays
			contain valid values.  Type ide_reg_valid_t.
    in_flags		flags indicating which entries in the
			io_ports[] and hob_ports[] arrays
			are expected to contain valid values
			on return.
    data_phase		See below
    req_cmd		Command type, see below
    out_size		output (user->drive) buffer size, bytes
    in_size		input (drive->user) buffer size, bytes
    ============	===============================================

  When out_flags is zero, the following registers are loaded.

    ============	===============================================
    HOB_FEATURE		If the drive supports LBA48
    HOB_NSECTOR		If the drive supports LBA48
    HOB_SECTOR		If the drive supports LBA48
    HOB_LCYL		If the drive supports LBA48
    HOB_HCYL		If the drive supports LBA48
    FEATURE
    NSECTOR
    SECTOR
    LCYL
    HCYL
    SELECT		First, masked with 0xE0 if LBA48, 0xEF
			otherwise; then, or'ed with the default
			value of SELECT.
    ============	===============================================

  If any bit in out_flags is set, the following registers are loaded.

    ============	===============================================
    HOB_DATA		If out_flags.b.data is set.  HOB_DATA will
			travel on DD8-DD15 on little endian machines
			and on DD0-DD7 on big endian machines.
    DATA		If out_flags.b.data is set.  DATA will
			travel on DD0-DD7 on little endian machines
			and on DD8-DD15 on big endian machines.
    HOB_NSECTOR		If out_flags.b.nsector_hob is set
    HOB_SECTOR		If out_flags.b.sector_hob is set
    HOB_LCYL		If out_flags.b.lcyl_hob is set
    HOB_HCYL		If out_flags.b.hcyl_hob is set
    FEATURE		If out_flags.b.feature is set
    NSECTOR		If out_flags.b.nsector is set
    SECTOR		If out_flags.b.sector is set
    LCYL		If out_flags.b.lcyl is set
    HCYL		If out_flags.b.hcyl is set
    SELECT		Or'ed with the default value of SELECT and
			loaded regardless of out_flags.b.select.
    ============	===============================================

  Taskfile registers are read back from the drive into
  {io|hob}_ports[] after the command completes iff one of the
  following conditions is met; otherwise, the original values
  will be written back, unchanged.

    1. The drive fails the command (EIO).
    2. One or more than one bits are set in out_flags.
    3. The requested data_phase is TASKFILE_NO_DATA.

    ============	===============================================
    HOB_DATA		If in_flags.b.data is set.  It will contain
			DD8-DD15 on little endian machines and
			DD0-DD7 on big endian machines.
    DATA		If in_flags.b.data is set.  It will contain
			DD0-DD7 on little endian machines and
			DD8-DD15 on big endian machines.
    HOB_FEATURE		If the drive supports LBA48
    HOB_NSECTOR		If the drive supports LBA48
    HOB_SECTOR		If the drive supports LBA48
    HOB_LCYL		If the drive supports LBA48
    HOB_HCYL		If the drive supports LBA48
    NSECTOR
    SECTOR
    LCYL
    HCYL
    ============	===============================================

  The data_phase field describes the data transfer to be
  performed.  Value is one of:

    ===================        ========================================
    TASKFILE_IN
    TASKFILE_MULTI_IN
    TASKFILE_OUT
    TASKFILE_MULTI_OUT
    TASKFILE_IN_OUT
    TASKFILE_IN_DMA
    TASKFILE_IN_DMAQ		== IN_DMA (queueing not supported)
    TASKFILE_OUT_DMA
    TASKFILE_OUT_DMAQ		== OUT_DMA (queueing not supported)
    TASKFILE_P_IN		unimplemented
    TASKFILE_P_IN_DMA		unimplemented
    TASKFILE_P_IN_DMAQ		unimplemented
    TASKFILE_P_OUT		unimplemented
    TASKFILE_P_OUT_DMA		unimplemented
    TASKFILE_P_OUT_DMAQ		unimplemented
    ===================        ========================================

  The req_cmd field classifies the command type.  It may be
  one of:

    ========================    =======================================
    IDE_DRIVE_TASK_NO_DATA
    IDE_DRIVE_TASK_SET_XFER	unimplemented
    IDE_DRIVE_TASK_IN
    IDE_DRIVE_TASK_OUT		unimplemented
    IDE_DRIVE_TASK_RAW_WRITE
    ========================    =======================================

  [6] Do not access {in|out}_flags->all except for resetting
  all the bits.  Always access individual bit fields.  ->all
  value will flip depending on endianness.  For the same
  reason, do not use IDE_{TASKFILE|HOB}_STD_{OUT|IN}_FLAGS
  constants defined in hdreg.h.

Note:  If you don't have a copy of the ANSI ATA specification
handy, you should probably ignore this ioctl.

usage::

  u8 args[4+XFER_SIZE];

  ...
  ioctl(fd, HDIO_DRIVE_CMD, args);

inputs:
    Commands other than WIN_SMART:

    =======     =======
    args[0]	COMMAND
    args[1]	NSECTOR
    args[2]	FEATURE
    args[3]	NSECTOR
    =======     =======

    WIN_SMART:

    =======     =======
    args[0]	COMMAND
    args[1]	SECTOR
    args[2]	FEATURE
    args[3]	NSECTOR
    =======     =======

outputs:
	args[] buffer is filled with register values followed by any


  data returned by the disk.

    ========	====================================================
    args[0]	status
    args[1]	error
    args[2]	NSECTOR
    args[3]	undefined
    args[4+]	NSECTOR * 512 bytes of data returned by the command.
    ========	====================================================

error returns:
  - EACCES	Access denied:  requires CAP_SYS_RAWIO
  - ENOMEM	Unable to allocate memory for task
  - EIO		Drive reports error

notes:

  [1] For commands other than WIN_SMART, args[1] should equal
  args[3].  SECTOR, LCYL and HCYL are undefined.  For
  WIN_SMART, 0x4f and 0xc2 are loaded into LCYL and HCYL
  respectively.  In both cases SELECT will contain the default
  value for the drive.  Please refer to HDIO_DRIVE_TASKFILE
  notes for the default value of SELECT.

  [2] If NSECTOR value is greater than zero and the drive sets
  DRQ when interrupting for the command, NSECTOR * 512 bytes
  are read from the device into the area following NSECTOR.
  In the above example, the area would be
  args[4..4+XFER_SIZE].  16bit PIO is used regardless of
  HDIO_SET_32BIT setting.

  [3] If COMMAND == WIN_SETFEATURES && FEATURE == SETFEATURES_XFER
  && NSECTOR >= XFER_SW_DMA_0 && the drive supports any DMA
  mode, IDE driver will try to tune the transfer mode of the
  drive accordingly.

Note:  If you don't have a copy of the ANSI ATA specification
handy, you should probably ignore this ioctl.

usage::

  u8 args[7];

  ...
  ioctl(fd, HDIO_DRIVE_TASK, args);

inputs:
    Taskfile register values:

    =======	=======
    args[0]	COMMAND
    args[1]	FEATURE
    args[2]	NSECTOR
    args[3]	SECTOR
    args[4]	LCYL
    args[5]	HCYL
    args[6]	SELECT
    =======	=======

outputs:
    Taskfile register values:


    =======	=======
    args[0]	status
    args[1]	error
    args[2]	NSECTOR
    args[3]	SECTOR
    args[4]	LCYL
    args[5]	HCYL
    args[6]	SELECT
    =======	=======

error returns:
  - EACCES	Access denied:  requires CAP_SYS_RAWIO
  - ENOMEM	Unable to allocate memory for task
  - ENOMSG	Device is not a disk drive.
  - EIO		Drive failed the command.

notes:

  [1] DEV bit (0x10) of SELECT register is ignored and the
  appropriate value for the drive is used.  All other bits
  are used unaltered.

usage::

  int val;

  ioctl(fd, HDIO_SET_32BIT, val);

inputs:
	New value for io_32bit flag



outputs:
	none



error return:
  - EINVAL	Called on a partition instead of the whole disk device
  - EACCES	Access denied:  requires CAP_SYS_ADMIN
  - EINVAL	value out of range [0 3]
  - EBUSY	Controller busy