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