1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 #ifndef _ASM_GENERIC_IOCTL_H 3 #define _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 #define _IOC_TYPECHECK(t) (sizeof(t)) 76 77 /* 78 * Used to create numbers. 79 * 80 * NOTE: _IOW means userland is writing and kernel is reading. _IOR 81 * means userland is reading and kernel is writing. 82 */ 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 */