include/asm-i386/ioctl.h

   1 /* $Id: ioctl.h,v 1.5 1993/07/19 21:53:50 root Exp root $
   2  *
   3  * linux/ioctl.h for Linux by H.H. Bergman.
   4  */
   5
   6 #ifndef _ASMI386_IOCTL_H
   7 #define _ASMI386_IOCTL_H
   8
   9 /* ioctl command encoding: 32 bits total, command in lower 16 bits,
  10  * size of the parameter structure in the lower 14 bits of the
  11  * upper 16 bits.
  12  * Encoding the size of the parameter structure in the ioctl request
  13  * is useful for catching programs compiled with old versions
  14  * and to avoid overwriting user space outside the user buffer area.
  15  * The highest 2 bits are reserved for indicating the ``access mode''.
  16  * NOTE: This limits the max parameter size to 16kB -1 !
  17  */
  18
  19 /*
  20  * The following is for compatibility across the various Linux
  21  * platforms.  The i386 ioctl numbering scheme doesn't really enforce
  22  * a type field.  De facto, however, the top 8 bits of the lower 16
  23  * bits are indeed used as a type field, so we might just as well make
  24  * this explicit here.  Please be sure to use the decoding macros
  25  * below from now on.
  26  */
  27 #define _IOC_NRBITS     8
  28 #define _IOC_TYPEBITS   8
  29 #define _IOC_SIZEBITS   14
  30 #define _IOC_DIRBITS    2
  31
  32 #define _IOC_NRMASK     ((1 << _IOC_NRBITS)-1)
  33 #define _IOC_TYPEMASK   ((1 << _IOC_TYPEBITS)-1)
  34 #define _IOC_SIZEMASK   ((1 << _IOC_SIZEBITS)-1)
  35 #define _IOC_DIRMASK    ((1 << _IOC_DIRBITS)-1)
  36
  37 #define _IOC_NRSHIFT    0
  38 #define _IOC_TYPESHIFT  (_IOC_NRSHIFT+_IOC_NRBITS)
  39 #define _IOC_SIZESHIFT  (_IOC_TYPESHIFT+_IOC_TYPEBITS)
  40 #define _IOC_DIRSHIFT   (_IOC_SIZESHIFT+_IOC_SIZEBITS)
  41
  42 /*
  43  * Direction bits.
  44  */
  45 #define _IOC_NONE       0U
  46 #define _IOC_WRITE      1U
  47 #define _IOC_READ       2U
  48
  49 #define _IOC(dir,type,nr,size) \
  50         (((dir)  << _IOC_DIRSHIFT) | \
  51          ((type) << _IOC_TYPESHIFT) | \
  52          ((nr)   << _IOC_NRSHIFT) | \
  53          ((size) << _IOC_SIZESHIFT))
  54
  55 /* provoke compile error for invalid uses of size argument */
  56 extern unsigned int __invalid_size_argument_for_IOC;
  57 #define _IOC_TYPECHECK(t) \
  58         ((sizeof(t) == sizeof(t[1]) && \
  59           sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
  60           sizeof(t) : __invalid_size_argument_for_IOC)
  61
  62 /* used to create numbers */
  63 #define _IO(type,nr)            _IOC(_IOC_NONE,(type),(nr),0)
  64 #define _IOR(type,nr,size)      _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
  65 #define _IOW(type,nr,size)      _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  66 #define _IOWR(type,nr,size)     _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  67 #define _IOR_BAD(type,nr,size)  _IOC(_IOC_READ,(type),(nr),sizeof(size))
  68 #define _IOW_BAD(type,nr,size)  _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
  69 #define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
  70
  71 /* used to decode ioctl numbers.. */
  72 #define _IOC_DIR(nr)            (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
  73 #define _IOC_TYPE(nr)           (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
  74 #define _IOC_NR(nr)             (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
  75 #define _IOC_SIZE(nr)           (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
  76
  77 /* ...and for the drivers/sound files... */
  78
  79 #define IOC_IN          (_IOC_WRITE << _IOC_DIRSHIFT)
  80 #define IOC_OUT         (_IOC_READ << _IOC_DIRSHIFT)
  81 #define IOC_INOUT       ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
  82 #define IOCSIZE_MASK    (_IOC_SIZEMASK << _IOC_SIZESHIFT)
  83 #define IOCSIZE_SHIFT   (_IOC_SIZESHIFT)
  84
  85 #endif /* _ASMI386_IOCTL_H */