include/asm-arm/ioctl.h

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