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      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 
     53 #ifndef _IOC_NONE
     54 # define _IOC_NONE	0U
     55 #endif
     56 
     57 #ifndef _IOC_WRITE
     58 # define _IOC_WRITE	1U
     59 #endif
     60 
     61 #ifndef _IOC_READ
     62 # define _IOC_READ	2U
     63 #endif
     64 
     65 #define _IOC(dir,type,nr,size) \
     66 	(((dir)  << _IOC_DIRSHIFT) | \
     67 	 ((type) << _IOC_TYPESHIFT) | \
     68 	 ((nr)   << _IOC_NRSHIFT) | \
     69 	 ((size) << _IOC_SIZESHIFT))
     70 
     71 #ifndef __KERNEL__
     72 #define _IOC_TYPECHECK(t) (sizeof(t))
     73 #endif
     74 
     75 /* used to create numbers */
     76 #define _IO(type,nr)		_IOC(_IOC_NONE,(type),(nr),0)
     77 #define _IOR(type,nr,size)	_IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
     78 #define _IOW(type,nr,size)	_IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
     79 #define _IOWR(type,nr,size)	_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
     80 #define _IOR_BAD(type,nr,size)	_IOC(_IOC_READ,(type),(nr),sizeof(size))
     81 #define _IOW_BAD(type,nr,size)	_IOC(_IOC_WRITE,(type),(nr),sizeof(size))
     82 #define _IOWR_BAD(type,nr,size)	_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
     83 
     84 /* used to decode ioctl numbers.. */
     85 #define _IOC_DIR(nr)		(((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
     86 #define _IOC_TYPE(nr)		(((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
     87 #define _IOC_NR(nr)		(((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
     88 #define _IOC_SIZE(nr)		(((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
     89 
     90 /* ...and for the drivers/sound files... */
     91 
     92 #define IOC_IN		(_IOC_WRITE << _IOC_DIRSHIFT)
     93 #define IOC_OUT		(_IOC_READ << _IOC_DIRSHIFT)
     94 #define IOC_INOUT	((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
     95 #define IOCSIZE_MASK	(_IOC_SIZEMASK << _IOC_SIZESHIFT)
     96 #define IOCSIZE_SHIFT	(_IOC_SIZESHIFT)
     97 
     98 #endif /* _UAPI_ASM_GENERIC_IOCTL_H */
     99