LXR linux/include/uapi/asm-generic/ioctl.h

   1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2#ifndef _UAPI_ASM_GENERIC_IOCTL_H
   3#define _UAPI_ASM_GENERIC_IOCTL_H
   4
   5/* ioctl command encoding: 32 bits total, command in lower 16 bits,
   6 * size of the parameter structure in the lower 14 bits of the
   7 * upper 16 bits.
   8 * Encoding the size of the parameter structure in the ioctl request
   9 * is useful for catching programs compiled with old versions
  10 * and to avoid overwriting user space outside the user buffer area.
  11 * The highest 2 bits are reserved for indicating the ``access mode''.
  12 * NOTE: This limits the max parameter size to 16kB -1 !
  13 */
  14
  15/*
  16 * The following is for compatibility across the various Linux
  17 * platforms.  The generic ioctl numbering scheme doesn't really enforce
  18 * a type field.  De facto, however, the top 8 bits of the lower 16
  19 * bits are indeed used as a type field, so we might just as well make
  20 * this explicit here.  Please be sure to use the decoding macros
  21 * below from now on.
  22 */
  23#define _IOC_NRBITS     8
  24#define _IOC_TYPEBITS   8
  25
  26/*
  27 * Let any architecture override either of the following before
  28 * including this file.
  29 */
  30
  31#ifndef _IOC_SIZEBITS
  32# define _IOC_SIZEBITS  14
  33#endif
  34
  35#ifndef _IOC_DIRBITS
  36# define _IOC_DIRBITS   2
  37#endif
  38
  39#define _IOC_NRMASK     ((1 << _IOC_NRBITS)-1)
  40#define _IOC_TYPEMASK   ((1 << _IOC_TYPEBITS)-1)
  41#define _IOC_SIZEMASK   ((1 << _IOC_SIZEBITS)-1)
  42#define _IOC_DIRMASK    ((1 << _IOC_DIRBITS)-1)
  43
  44#define _IOC_NRSHIFT    0
  45#define _IOC_TYPESHIFT  (_IOC_NRSHIFT+_IOC_NRBITS)
  46#define _IOC_SIZESHIFT  (_IOC_TYPESHIFT+_IOC_TYPEBITS)
  47#define _IOC_DIRSHIFT   (_IOC_SIZESHIFT+_IOC_SIZEBITS)
  48
  49/*
  50 * Direction bits, which any architecture can choose to override
  51 * before including this file.
  52 *
  53 * NOTE: _IOC_WRITE means userland is writing and kernel is
  54 * reading. _IOC_READ means userland is reading and kernel is writing.
  55 */
  56
  57#ifndef _IOC_NONE
  58# define _IOC_NONE      0U
  59#endif
  60
  61#ifndef _IOC_WRITE
  62# define _IOC_WRITE     1U
  63#endif
  64
  65#ifndef _IOC_READ
  66# define _IOC_READ      2U
  67#endif
  68
  69#define _IOC(dir,type,nr,size) \
  70        (((dir)  << _IOC_DIRSHIFT) | \
  71         ((type) << _IOC_TYPESHIFT) | \
  72         ((nr)   << _IOC_NRSHIFT) | \
  73         ((size) << _IOC_SIZESHIFT))
  74
  75#ifndef __KERNEL__
  76#define _IOC_TYPECHECK(t) (sizeof(t))
  77#endif
  78
  79/*
  80 * Used to create numbers.
  81 *
  82 * NOTE: _IOW means userland is writing and kernel is reading. _IOR
  83 * means userland is reading and kernel is writing.
  84 */
  85#define _IO(type,nr)            _IOC(_IOC_NONE,(type),(nr),0)
  86#define _IOR(type,nr,size)      _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
  87#define _IOW(type,nr,size)      _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  88#define _IOWR(type,nr,size)     _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  89#define _IOR_BAD(type,nr,size)  _IOC(_IOC_READ,(type),(nr),sizeof(size))
  90#define _IOW_BAD(type,nr,size)  _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
  91#define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
  92
  93/* used to decode ioctl numbers.. */
  94#define _IOC_DIR(nr)            (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
  95#define _IOC_TYPE(nr)           (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
  96#define _IOC_NR(nr)             (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
  97#define _IOC_SIZE(nr)           (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
  98
  99/* ...and for the drivers/sound files... */
 100
 101#define IOC_IN          (_IOC_WRITE << _IOC_DIRSHIFT)
 102#define IOC_OUT         (_IOC_READ << _IOC_DIRSHIFT)
 103#define IOC_INOUT       ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
 104#define IOCSIZE_MASK    (_IOC_SIZEMASK << _IOC_SIZESHIFT)
 105#define IOCSIZE_SHIFT   (_IOC_SIZESHIFT)
 106
 107#endif /* _UAPI_ASM_GENERIC_IOCTL_H */
 108