blob: 543f7843d553a7ac9b2b673a9920c858171535ab [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* $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 */
56extern 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 */