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 */
51 extern 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
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