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+==============================
+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 5.11)
+drivers/ata/libata-scsi.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_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
+ ======================= =======================================
+
+
+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_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 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
+
+
+
+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_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_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 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