ioctl.h (3519B)
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 */