10521bd9f7
In the spirit of a number of other asm-generic header files, generalize asm-generic/ioctl.h to allow arch-specific ioctl.h headers to simply override _IOC_SIZEBITS and/or _IOC_DIRBITS before including this header file, allowing a number of ioctl.h header files to be shortened considerably. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
102 lines
3.3 KiB
C
102 lines
3.3 KiB
C
#ifndef _ASM_GENERIC_IOCTL_H
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#define _ASM_GENERIC_IOCTL_H
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/* ioctl command encoding: 32 bits total, command in lower 16 bits,
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* size of the parameter structure in the lower 14 bits of the
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* upper 16 bits.
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* Encoding the size of the parameter structure in the ioctl request
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* is useful for catching programs compiled with old versions
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* and to avoid overwriting user space outside the user buffer area.
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* The highest 2 bits are reserved for indicating the ``access mode''.
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* NOTE: This limits the max parameter size to 16kB -1 !
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*/
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/*
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* The following is for compatibility across the various Linux
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* platforms. The generic ioctl numbering scheme doesn't really enforce
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* a type field. De facto, however, the top 8 bits of the lower 16
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* bits are indeed used as a type field, so we might just as well make
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* this explicit here. Please be sure to use the decoding macros
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* below from now on.
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*/
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#define _IOC_NRBITS 8
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#define _IOC_TYPEBITS 8
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/*
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* Let any architecture override either of the following before
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* including this file.
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*/
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#ifndef _IOC_SIZEBITS
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# define _IOC_SIZEBITS 14
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#endif
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#ifndef _IOC_DIRBITS
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# define _IOC_DIRBITS 2
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#endif
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#define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
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#define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
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#define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1)
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#define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1)
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#define _IOC_NRSHIFT 0
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#define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS)
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#define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS)
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#define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)
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/*
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* Direction bits, which any architecture can choose to override
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* before including this file.
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*/
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#ifndef _IOC_NONE
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# define _IOC_NONE 0U
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#endif
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#ifndef _IOC_WRITE
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# define _IOC_WRITE 1U
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#endif
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#ifndef _IOC_READ
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# define _IOC_READ 2U
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#endif
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#define _IOC(dir,type,nr,size) \
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(((dir) << _IOC_DIRSHIFT) | \
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((type) << _IOC_TYPESHIFT) | \
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((nr) << _IOC_NRSHIFT) | \
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((size) << _IOC_SIZESHIFT))
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/* provoke compile error for invalid uses of size argument */
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extern unsigned int __invalid_size_argument_for_IOC;
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#define _IOC_TYPECHECK(t) \
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((sizeof(t) == sizeof(t[1]) && \
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sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
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sizeof(t) : __invalid_size_argument_for_IOC)
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/* used to create numbers */
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#define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
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#define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
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#define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
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#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
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#define _IOR_BAD(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
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#define _IOW_BAD(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
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#define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
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/* used to decode ioctl numbers.. */
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#define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
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#define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
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#define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
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#define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
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/* ...and for the drivers/sound files... */
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#define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT)
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#define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT)
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#define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
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#define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
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#define IOCSIZE_SHIFT (_IOC_SIZESHIFT)
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#endif /* _ASM_GENERIC_IOCTL_H */
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