Root/include/asm-generic/ioctl.h

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
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#ifdef __KERNEL__
72/* provoke compile error for invalid uses of size argument */
73extern unsigned int __invalid_size_argument_for_IOC;
74#define _IOC_TYPECHECK(t) \
75    ((sizeof(t) == sizeof(t[1]) && \
76      sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
77      sizeof(t) : __invalid_size_argument_for_IOC)
78#else
79#define _IOC_TYPECHECK(t) (sizeof(t))
80#endif
81
82/* used to create numbers */
83#define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
84#define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
85#define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
86#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
87#define _IOR_BAD(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
88#define _IOW_BAD(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
89#define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
90
91/* used to decode ioctl numbers.. */
92#define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
93#define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
94#define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
95#define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
96
97/* ...and for the drivers/sound files... */
98
99#define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT)
100#define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT)
101#define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
102#define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
103#define IOCSIZE_SHIFT (_IOC_SIZESHIFT)
104
105#endif /* _ASM_GENERIC_IOCTL_H */
106

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