include/uapi/asm-generic/ioctl.h

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