1#ifndef _ASM_GENERIC_IOCTL_H
2#define _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#define _IOC_SIZEBITS	14
25#define _IOC_DIRBITS	2
26
27#define _IOC_NRMASK	((1 << _IOC_NRBITS)-1)
28#define _IOC_TYPEMASK	((1 << _IOC_TYPEBITS)-1)
29#define _IOC_SIZEMASK	((1 << _IOC_SIZEBITS)-1)
30#define _IOC_DIRMASK	((1 << _IOC_DIRBITS)-1)
31
32#define _IOC_NRSHIFT	0
33#define _IOC_TYPESHIFT	(_IOC_NRSHIFT+_IOC_NRBITS)
34#define _IOC_SIZESHIFT	(_IOC_TYPESHIFT+_IOC_TYPEBITS)
35#define _IOC_DIRSHIFT	(_IOC_SIZESHIFT+_IOC_SIZEBITS)
36
37/*
38 * Direction bits.
39 */
40#define _IOC_NONE	0U
41#define _IOC_WRITE	1U
42#define _IOC_READ	2U
43
44#define _IOC(dir,type,nr,size) \
45	(((dir)  << _IOC_DIRSHIFT) | \
46	 ((type) << _IOC_TYPESHIFT) | \
47	 ((nr)   << _IOC_NRSHIFT) | \
48	 ((size) << _IOC_SIZESHIFT))
49
50/* provoke compile error for invalid uses of size argument */
51extern unsigned int __invalid_size_argument_for_IOC;
52#define _IOC_TYPECHECK(t) \
53	((sizeof(t) == sizeof(t[1]) && \
54	  sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
55	  sizeof(t) : __invalid_size_argument_for_IOC)
56
57/* used to create numbers */
58#define _IO(type,nr)		_IOC(_IOC_NONE,(type),(nr),0)
59#define _IOR(type,nr,size)	_IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
60#define _IOW(type,nr,size)	_IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
61#define _IOWR(type,nr,size)	_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
62#define _IOR_BAD(type,nr,size)	_IOC(_IOC_READ,(type),(nr),sizeof(size))
63#define _IOW_BAD(type,nr,size)	_IOC(_IOC_WRITE,(type),(nr),sizeof(size))
64#define _IOWR_BAD(type,nr,size)	_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
65
66/* used to decode ioctl numbers.. */
67#define _IOC_DIR(nr)		(((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
68#define _IOC_TYPE(nr)		(((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
69#define _IOC_NR(nr)		(((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
70#define _IOC_SIZE(nr)		(((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
71
72/* ...and for the drivers/sound files... */
73
74#define IOC_IN		(_IOC_WRITE << _IOC_DIRSHIFT)
75#define IOC_OUT		(_IOC_READ << _IOC_DIRSHIFT)
76#define IOC_INOUT	((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
77#define IOCSIZE_MASK	(_IOC_SIZEMASK << _IOC_SIZESHIFT)
78#define IOCSIZE_SHIFT	(_IOC_SIZESHIFT)
79
80#endif /* _ASM_GENERIC_IOCTL_H */
81