xref: /openbmc/linux/include/uapi/asm-generic/ioctl.h (revision 6f52b16c)
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _UAPI_ASM_GENERIC_IOCTL_H
3 #define _UAPI_ASM_GENERIC_IOCTL_H
4 
5 /* ioctl command encoding: 32 bits total, command in lower 16 bits,
6  * size of the parameter structure in the lower 14 bits of the
7  * upper 16 bits.
8  * Encoding the size of the parameter structure in the ioctl request
9  * is useful for catching programs compiled with old versions
10  * and to avoid overwriting user space outside the user buffer area.
11  * The highest 2 bits are reserved for indicating the ``access mode''.
12  * NOTE: This limits the max parameter size to 16kB -1 !
13  */
14 
15 /*
16  * The following is for compatibility across the various Linux
17  * platforms.  The generic ioctl numbering scheme doesn't really enforce
18  * a type field.  De facto, however, the top 8 bits of the lower 16
19  * bits are indeed used as a type field, so we might just as well make
20  * this explicit here.  Please be sure to use the decoding macros
21  * below from now on.
22  */
23 #define _IOC_NRBITS	8
24 #define _IOC_TYPEBITS	8
25 
26 /*
27  * Let any architecture override either of the following before
28  * including this file.
29  */
30 
31 #ifndef _IOC_SIZEBITS
32 # define _IOC_SIZEBITS	14
33 #endif
34 
35 #ifndef _IOC_DIRBITS
36 # define _IOC_DIRBITS	2
37 #endif
38 
39 #define _IOC_NRMASK	((1 << _IOC_NRBITS)-1)
40 #define _IOC_TYPEMASK	((1 << _IOC_TYPEBITS)-1)
41 #define _IOC_SIZEMASK	((1 << _IOC_SIZEBITS)-1)
42 #define _IOC_DIRMASK	((1 << _IOC_DIRBITS)-1)
43 
44 #define _IOC_NRSHIFT	0
45 #define _IOC_TYPESHIFT	(_IOC_NRSHIFT+_IOC_NRBITS)
46 #define _IOC_SIZESHIFT	(_IOC_TYPESHIFT+_IOC_TYPEBITS)
47 #define _IOC_DIRSHIFT	(_IOC_SIZESHIFT+_IOC_SIZEBITS)
48 
49 /*
50  * Direction bits, which any architecture can choose to override
51  * before including this file.
52  *
53  * NOTE: _IOC_WRITE means userland is writing and kernel is
54  * reading. _IOC_READ means userland is reading and kernel is writing.
55  */
56 
57 #ifndef _IOC_NONE
58 # define _IOC_NONE	0U
59 #endif
60 
61 #ifndef _IOC_WRITE
62 # define _IOC_WRITE	1U
63 #endif
64 
65 #ifndef _IOC_READ
66 # define _IOC_READ	2U
67 #endif
68 
69 #define _IOC(dir,type,nr,size) \
70 	(((dir)  << _IOC_DIRSHIFT) | \
71 	 ((type) << _IOC_TYPESHIFT) | \
72 	 ((nr)   << _IOC_NRSHIFT) | \
73 	 ((size) << _IOC_SIZESHIFT))
74 
75 #ifndef __KERNEL__
76 #define _IOC_TYPECHECK(t) (sizeof(t))
77 #endif
78 
79 /*
80  * Used to create numbers.
81  *
82  * NOTE: _IOW means userland is writing and kernel is reading. _IOR
83  * means userland is reading and kernel is writing.
84  */
85 #define _IO(type,nr)		_IOC(_IOC_NONE,(type),(nr),0)
86 #define _IOR(type,nr,size)	_IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
87 #define _IOW(type,nr,size)	_IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
88 #define _IOWR(type,nr,size)	_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
89 #define _IOR_BAD(type,nr,size)	_IOC(_IOC_READ,(type),(nr),sizeof(size))
90 #define _IOW_BAD(type,nr,size)	_IOC(_IOC_WRITE,(type),(nr),sizeof(size))
91 #define _IOWR_BAD(type,nr,size)	_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
92 
93 /* used to decode ioctl numbers.. */
94 #define _IOC_DIR(nr)		(((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
95 #define _IOC_TYPE(nr)		(((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
96 #define _IOC_NR(nr)		(((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
97 #define _IOC_SIZE(nr)		(((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
98 
99 /* ...and for the drivers/sound files... */
100 
101 #define IOC_IN		(_IOC_WRITE << _IOC_DIRSHIFT)
102 #define IOC_OUT		(_IOC_READ << _IOC_DIRSHIFT)
103 #define IOC_INOUT	((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
104 #define IOCSIZE_MASK	(_IOC_SIZEMASK << _IOC_SIZESHIFT)
105 #define IOCSIZE_SHIFT	(_IOC_SIZESHIFT)
106 
107 #endif /* _UAPI_ASM_GENERIC_IOCTL_H */
108