Kernel-3.10.0-957.el7_hdio

    Summary of HDIO_ ioctl calls.
    ============================

    Edward A. Falk <efalk@google.com>

    November, 2004

This document attempts to describe the ioctl(2) calls supported by
the HD/IDE layer. These are by-and-large implemented (as of Linux 2.6)
in drivers/ide/ide.c and drivers/block/scsi_ioctl.c

ioctl values are listed in <linux/hdreg.h>. As of this writing, they
are as follows:

ioctls that pass argument pointers to user space:

HDIO_GETGEO        get device geometry
HDIO_GET_UNMASKINTR    get current unmask setting
HDIO_GET_MULTCOUNT    get current IDE blockmode setting
HDIO_GET_QDMA        get use-qdma flag
HDIO_SET_XFER        set transfer rate via proc
HDIO_OBSOLETE_IDENTITY    OBSOLETE, DO NOT USE
HDIO_GET_KEEPSETTINGS    get keep-settings-on-reset flag
HDIO_GET_32BIT        get current io_32bit setting
HDIO_GET_NOWERR        get ignore-write-error flag
HDIO_GET_DMA        get use-dma flag
HDIO_GET_NICE        get nice flags
HDIO_GET_IDENTITY    get IDE identification info
HDIO_GET_WCACHE        get write cache mode on|off
HDIO_GET_ACOUSTIC    get acoustic value
HDIO_GET_ADDRESS    get sector addressing mode
HDIO_GET_BUSSTATE    get the bus state of the hwif
HDIO_TRISTATE_HWIF    execute a channel tristate
HDIO_DRIVE_RESET    execute a device reset
HDIO_DRIVE_TASKFILE    execute raw taskfile
HDIO_DRIVE_TASK        execute task and special drive command
HDIO_DRIVE_CMD        execute a special drive command
HDIO_DRIVE_CMD_AEB    HDIO_DRIVE_TASK

ioctls that pass non-pointer values:

HDIO_SET_MULTCOUNT    change IDE blockmode
HDIO_SET_UNMASKINTR    permit other irqs during I/O
HDIO_SET_KEEPSETTINGS    keep ioctl settings on reset
HDIO_SET_32BIT        change io_32bit flags
HDIO_SET_NOWERR        change ignore-write-error flag
HDIO_SET_DMA        change use-dma flag
HDIO_SET_PIO_MODE    reconfig interface to new speed
HDIO_SCAN_HWIF        register and (re)scan interface
HDIO_SET_NICE        set nice flags
HDIO_UNREGISTER_HWIF    unregister interface
HDIO_SET_WCACHE        change write cache enable-disable
HDIO_SET_ACOUSTIC    change acoustic behavior
HDIO_SET_BUSSTATE    set the bus state of the hwif
HDIO_SET_QDMA        change use-qdma flag
HDIO_SET_ADDRESS    change lba addressing modes

HDIO_SET_IDE_SCSI    Set scsi emulation mode on/off
HDIO_SET_SCSI_IDE    not implemented yet

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.

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>

HDIO_GETGEO get device geometry

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.

HDIO_GET_UNMASKINTR get current unmask setting

usage:

  long val;
  ioctl(fd, HDIO_GET_UNMASKINTR, &val);

inputs:        none

outputs:
  The value of the drive's current unmask setting

HDIO_SET_UNMASKINTR permit other irqs during I/O

usage:

  unsigned long val;
  ioctl(fd, HDIO_SET_UNMASKINTR, val);

inputs:
  New value for unmask flag

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 1]
  EBUSY        Controller busy

HDIO_GET_MULTCOUNT get current IDE blockmode setting

usage:

  long val;
  ioctl(fd, HDIO_GET_MULTCOUNT, &val);

inputs:        none

outputs:
  The value of the current IDE block mode setting.  This
  controls how many sectors the drive will transfer per
  interrupt.

HDIO_SET_MULTCOUNT change IDE blockmode

usage:

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

inputs:
  New value for IDE block mode setting.  This controls how many
  sectors the drive will transfer per interrupt.

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range supported by disk.
  EBUSY        Controller busy or blockmode already set.
  EIO        Drive did not accept new block mode.

notes:

  Source code comments read:

    This is tightly woven into the driver->do_special cannot
    touch.  DON'T do it again until a total personality rewrite
    is committed.

  If blockmode has already been set, this ioctl will fail with
  EBUSY

HDIO_GET_QDMA get use-qdma flag

Not implemented, as of 2.6.8.1

HDIO_SET_XFER set transfer rate via proc

Not implemented, as of 2.6.8.1

HDIO_OBSOLETE_IDENTITY OBSOLETE, DO NOT USE

Same as HDIO_GET_IDENTITY (see below), except that it only
returns the first 142 bytes of drive identity information.

HDIO_GET_IDENTITY get IDE identification info

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    (bdev != bdev->bd_contains) (not sure what this means)
  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

HDIO_GET_KEEPSETTINGS get keep-settings-on-reset flag

usage:

  long val;
  ioctl(fd, HDIO_GET_KEEPSETTINGS, &val);

inputs:        none

outputs:
  The value of the current "keep settings" flag

notes:

  When set, indicates that kernel should restore settings
  after a drive reset.

HDIO_SET_KEEPSETTINGS keep ioctl settings on reset

usage:

  long val;
  ioctl(fd, HDIO_SET_KEEPSETTINGS, val);

inputs:
  New value for keep_settings flag

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 1]
  EBUSY        Controller busy

HDIO_GET_32BIT get current io_32bit setting

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

HDIO_GET_NOWERR get ignore-write-error flag

usage:

  long val;
  ioctl(fd, HDIO_GET_NOWERR, &val);

inputs:        none

outputs:
  The value of the current ignore-write-error flag

HDIO_GET_DMA get use-dma flag

usage:

  long val;
  ioctl(fd, HDIO_GET_DMA, &val);

inputs:        none

outputs:
  The value of the current use-dma flag

HDIO_GET_NICE get nice flags

usage:

  long nice;
  ioctl(fd, HDIO_GET_NICE, &nice);

inputs:        none

outputs:

  The drive's "nice" values.

notes:

  Per-drive flags which determine when the system will give more
  bandwidth to other devices sharing the same IDE bus.
  See <linux/hdreg.h>, near symbol IDE_NICE_DSC_OVERLAP.

HDIO_SET_NICE set nice flags

usage:

  unsigned long nice;
  ...
  ioctl(fd, HDIO_SET_NICE, nice);

inputs:
  bitmask of nice flags.

outputs:    none

error returns:
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EPERM        Flags other than DSC_OVERLAP and NICE_1 set.
  EPERM        DSC_OVERLAP specified but not supported by drive

notes:

  This ioctl sets the DSC_OVERLAP and NICE_1 flags from values
  provided by the user.

  Nice flags are listed in <linux/hdreg.h>, starting with
  IDE_NICE_DSC_OVERLAP.  These values represent shifts.

HDIO_GET_WCACHE get write cache mode on|off

usage:

  long val;
  ioctl(fd, HDIO_GET_WCACHE, &val);

inputs:        none

outputs:
  The value of the current write cache mode

HDIO_GET_ACOUSTIC get acoustic value

usage:

  long val;
  ioctl(fd, HDIO_GET_ACOUSTIC, &val);

inputs:        none

outputs:
  The value of the current acoustic settings

notes:

  See HDIO_SET_ACOUSTIC

HDIO_GET_ADDRESS

usage:

  long val;
  ioctl(fd, HDIO_GET_ADDRESS, &val);

inputs:        none

outputs:
  The value of the current addressing mode:
    0 = 28-bit
    1 = 48-bit
    2 = 48-bit doing 28-bit
    3 = 64-bit

HDIO_GET_BUSSTATE get the bus state of the hwif

usage:

  long state;
  ioctl(fd, HDIO_SCAN_HWIF, &state);

inputs:        none

outputs:
  Current power state of the IDE bus.  One of BUSSTATE_OFF,
  BUSSTATE_ON, or BUSSTATE_TRISTATE

error returns:
  EACCES    Access denied:  requires CAP_SYS_ADMIN

HDIO_SET_BUSSTATE set the bus state of the hwif

usage:

  int state;
  ...
  ioctl(fd, HDIO_SCAN_HWIF, state);

inputs:
  Desired IDE power state.  One of BUSSTATE_OFF, BUSSTATE_ON,
  or BUSSTATE_TRISTATE

outputs:    none

error returns:
  EACCES    Access denied:  requires CAP_SYS_RAWIO
  EOPNOTSUPP    Hardware interface does not support bus power control

HDIO_TRISTATE_HWIF execute a channel tristate

Not implemented, as of 2.6.8.1.  See HDIO_SET_BUSSTATE

HDIO_DRIVE_RESET execute a device reset

usage:

  int args[3]
  ...
  ioctl(fd, HDIO_DRIVE_RESET, args);

inputs:        none

outputs:    none

error returns:
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  ENXIO        No such device:    phy dead or ctl_addr == 0
  EIO        I/O error:    reset timed out or hardware error

notes:

  Execute a reset on the device as soon as the current IO
  operation has completed.

  Executes an ATAPI soft reset if applicable, otherwise
  executes an ATA soft reset on the controller.

HDIO_DRIVE_TASKFILE execute raw taskfile

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.

HDIO_DRIVE_CMD execute a special drive command

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.

HDIO_DRIVE_TASK execute task and special drive command

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.

HDIO_DRIVE_CMD_AEB HDIO_DRIVE_TASK

Not implemented, as of 2.6.8.1

HDIO_SET_32BIT change io_32bit flags

usage:

  int val;
  ioctl(fd, HDIO_SET_32BIT, val);

inputs:
  New value for io_32bit flag

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 3]
  EBUSY        Controller busy

HDIO_SET_NOWERR change ignore-write-error flag

usage:

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

inputs:
  New value for ignore-write-error flag.  Used for ignoring
  WRERR_STAT

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 1]
  EBUSY        Controller busy

HDIO_SET_DMA change use-dma flag

usage:

  long val;
  ioctl(fd, HDIO_SET_DMA, val);

inputs:
  New value for use-dma flag

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 1]
  EBUSY        Controller busy

HDIO_SET_PIO_MODE reconfig interface to new speed

usage:

  long val;
  ioctl(fd, HDIO_SET_PIO_MODE, val);

inputs:
  New interface speed.

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 255]
  EBUSY        Controller busy

HDIO_SCAN_HWIF register and (re)scan interface

usage:

  int args[3]
  ...
  ioctl(fd, HDIO_SCAN_HWIF, args);

inputs:
  args[0]    io address to probe
  args[1]    control address to probe
  args[2]    irq number

outputs:    none

error returns:
  EACCES    Access denied:  requires CAP_SYS_RAWIO
  EIO        Probe failed.

notes:

  This ioctl initializes the addresses and irq for a disk
  controller, probes for drives, and creates /proc/ide
  interfaces as appropriate.

HDIO_UNREGISTER_HWIF unregister interface

usage:

  int index;
  ioctl(fd, HDIO_UNREGISTER_HWIF, index);

inputs:
  index        index of hardware interface to unregister

outputs:    none

error returns:
  EACCES    Access denied:  requires CAP_SYS_RAWIO

notes:

  This ioctl removes a hardware interface from the kernel.

  Currently (2.6.8) this ioctl silently fails if any drive on
  the interface is busy.

HDIO_SET_WCACHE change write cache enable-disable

usage:

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

inputs:
  New value for write cache enable

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 1]
  EBUSY        Controller busy

HDIO_SET_ACOUSTIC change acoustic behavior

usage:

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

inputs:
  New value for drive acoustic settings

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 254]
  EBUSY        Controller busy

HDIO_SET_QDMA change use-qdma flag

Not implemented, as of 2.6.8.1

HDIO_SET_ADDRESS change lba addressing modes

usage:

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

inputs:
  New value for addressing mode
    0 = 28-bit
    1 = 48-bit
    2 = 48-bit doing 28-bit

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 2]
  EBUSY        Controller busy
  EIO        Drive does not support lba48 mode.

HDIO_SET_IDE_SCSI

usage:

  long val;
  ioctl(fd, HDIO_SET_IDE_SCSI, val);

inputs:
  New value for scsi emulation mode (?)

outputs:    none

error return:
  EINVAL    (bdev != bdev->bd_contains) (not sure what this means)
  EACCES    Access denied:  requires CAP_SYS_ADMIN
  EINVAL    value out of range [0 1]
  EBUSY        Controller busy

HDIO_SET_SCSI_IDE

Not implemented, as of 2.6.8.1