| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/ioctl.h for Linux by H.H. Bergman. |
| 3 | */ |
| 4 | |
| 5 | #ifndef _ASM_IOCTL_H |
| 6 | #define _ASM_IOCTL_H |
| 7 | |
| 8 | /* ioctl command encoding: 32 bits total, command in lower 16 bits, |
| 9 | * size of the parameter structure in the lower 14 bits of the |
| 10 | * upper 16 bits. |
| 11 | * Encoding the size of the parameter structure in the ioctl request |
| 12 | * is useful for catching programs compiled with old versions |
| 13 | * and to avoid overwriting user space outside the user buffer area. |
| 14 | * The highest 2 bits are reserved for indicating the ``access mode''. |
| 15 | * NOTE: This limits the max parameter size to 16kB -1 ! |
| 16 | */ |
| 17 | |
| 18 | /* |
| 19 | * I don't really have any idea about what this should look like, so |
| 20 | * for the time being, this is heavily based on the PC definitions. |
| 21 | */ |
| 22 | |
| 23 | /* |
| 24 | * The following is for compatibility across the various Linux |
| 25 | * platforms. The i386 ioctl numbering scheme doesn't really enforce |
| 26 | * a type field. De facto, however, the top 8 bits of the lower 16 |
| 27 | * bits are indeed used as a type field, so we might just as well make |
| 28 | * this explicit here. Please be sure to use the decoding macros |
| 29 | * below from now on. |
| 30 | */ |
| 31 | #define _IOC_NRBITS 8 |
| 32 | #define _IOC_TYPEBITS 8 |
| 33 | #define _IOC_SIZEBITS 14 |
| 34 | #define _IOC_DIRBITS 2 |
| 35 | |
| 36 | #define _IOC_NRMASK ((1 << _IOC_NRBITS)-1) |
| 37 | #define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1) |
| 38 | #define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1) |
| 39 | #define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1) |
| 40 | |
| 41 | #define _IOC_NRSHIFT 0 |
| 42 | #define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS) |
| 43 | #define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS) |
| 44 | #define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS) |
| 45 | |
| 46 | /* |
| 47 | * Direction bits. |
| 48 | */ |
| 49 | #define _IOC_NONE 0U |
| 50 | #define _IOC_WRITE 1U |
| 51 | #define _IOC_READ 2U |
| 52 | |
| 53 | #define _IOC(dir,type,nr,size) \ |
| 54 | (((dir) << _IOC_DIRSHIFT) | \ |
| 55 | ((type) << _IOC_TYPESHIFT) | \ |
| 56 | ((nr) << _IOC_NRSHIFT) | \ |
| 57 | ((size) << _IOC_SIZESHIFT)) |
| 58 | |
| 59 | /* used to create numbers */ |
| 60 | #define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0) |
| 61 | #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size)) |
| 62 | #define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size)) |
| 63 | #define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size)) |
| 64 | |
| 65 | /* used to decode ioctl numbers.. */ |
| 66 | #define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK) |
| 67 | #define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK) |
| 68 | #define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK) |
| 69 | #define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK) |
| 70 | |
| 71 | /* ...and for the drivers/sound files... */ |
| 72 | |
| 73 | #define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT) |
| 74 | #define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT) |
| 75 | #define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT) |
| 76 | #define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT) |
| 77 | #define IOCSIZE_SHIFT (_IOC_SIZESHIFT) |
| 78 | |
| 79 | #endif /* _ASM_IOCTL_H */ |
| 80 | |