include/asm-xtensa/ioctl.h

   1 /*
   2  * include/asm-xtensa/ioctl.h
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2003 - 2005 Tensilica Inc.
   9  *
  10  * Derived from "include/asm-i386/ioctl.h"
  11  */
  12
  13 #ifndef _XTENSA_IOCTL_H
  14 #define _XTENSA_IOCTL_H
  15
  16
  17 /* ioctl command encoding: 32 bits total, command in lower 16 bits,
  18  * size of the parameter structure in the lower 14 bits of the
  19  * upper 16 bits.
  20  * Encoding the size of the parameter structure in the ioctl request
  21  * is useful for catching programs compiled with old versions
  22  * and to avoid overwriting user space outside the user buffer area.
  23  * The highest 2 bits are reserved for indicating the ``access mode''.
  24  * NOTE: This limits the max parameter size to 16kB -1 !
  25  */
  26
  27 /*
  28  * The following is for compatibility across the various Linux
  29  * platforms.  The i386 ioctl numbering scheme doesn't really enforce
  30  * a type field.  De facto, however, the top 8 bits of the lower 16
  31  * bits are indeed used as a type field, so we might just as well make
  32  * this explicit here.  Please be sure to use the decoding macros
  33  * below from now on.
  34  */
  35 #define _IOC_NRBITS     8
  36 #define _IOC_TYPEBITS   8
  37 #define _IOC_SIZEBITS   14
  38 #define _IOC_DIRBITS    2
  39
  40 #define _IOC_NRMASK     ((1 << _IOC_NRBITS)-1)
  41 #define _IOC_TYPEMASK   ((1 << _IOC_TYPEBITS)-1)
  42 #define _IOC_SIZEMASK   ((1 << _IOC_SIZEBITS)-1)
  43 #define _IOC_DIRMASK    ((1 << _IOC_DIRBITS)-1)
  44
  45 #define _IOC_NRSHIFT    0
  46 #define _IOC_TYPESHIFT  (_IOC_NRSHIFT+_IOC_NRBITS)
  47 #define _IOC_SIZESHIFT  (_IOC_TYPESHIFT+_IOC_TYPEBITS)
  48 #define _IOC_DIRSHIFT   (_IOC_SIZESHIFT+_IOC_SIZEBITS)
  49
  50 /*
  51  * Direction bits.
  52  */
  53 #define _IOC_NONE       0U
  54 #define _IOC_WRITE      1U
  55 #define _IOC_READ       2U
  56
  57 #define _IOC(dir,type,nr,size) \
  58         (((dir)  << _IOC_DIRSHIFT) | \
  59          ((type) << _IOC_TYPESHIFT) | \
  60          ((nr)   << _IOC_NRSHIFT) | \
  61          ((size) << _IOC_SIZESHIFT))
  62
  63 /* used to create numbers */
  64 #define _IO(type,nr)            _IOC(_IOC_NONE,(type),(nr),0)
  65 #define _IOR(type,nr,size)      _IOC(_IOC_READ,(type),(nr),sizeof(size))
  66 #define _IOW(type,nr,size)      _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
  67 #define _IOWR(type,nr,size)     _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
  68
  69 /* used to decode ioctl numbers.. */
  70 #define _IOC_DIR(nr)            (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
  71 #define _IOC_TYPE(nr)           (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
  72 #define _IOC_NR(nr)             (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
  73 #define _IOC_SIZE(nr)           (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
  74
  75 /* ...and for the drivers/sound files... */
  76
  77 #define IOC_IN          (_IOC_WRITE << _IOC_DIRSHIFT)
  78 #define IOC_OUT         (_IOC_READ << _IOC_DIRSHIFT)
  79 #define IOC_INOUT       ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
  80 #define IOCSIZE_MASK    (_IOC_SIZEMASK << _IOC_SIZESHIFT)
  81 #define IOCSIZE_SHIFT   (_IOC_SIZESHIFT)
  82
  83 #endif