mirror of https://github.com/tLDP/LDP
67 lines
1.5 KiB
C
67 lines
1.5 KiB
C
/*
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* chardev.h - the header file with the ioctl definitions.
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*
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* The declarations here have to be in a header file, because
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* they need to be known both to the kernel module
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* (in chardev.c) and the process calling ioctl (ioctl.c)
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*/
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#ifndef CHARDEV_H
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#define CHARDEV_H
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#include <linux/ioctl.h>
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/*
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* The major device number. We can't rely on dynamic
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* registration any more, because ioctls need to know
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* it.
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*/
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#define MAJOR_NUM 100
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/*
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* Set the message of the device driver
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*/
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#define IOCTL_SET_MSG _IOR(MAJOR_NUM, 0, char *)
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/*
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* _IOR means that we're creating an ioctl command
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* number for passing information from a user process
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* to the kernel module.
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*
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* The first arguments, MAJOR_NUM, is the major device
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* number we're using.
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*
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* The second argument is the number of the command
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* (there could be several with different meanings).
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*
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* The third argument is the type we want to get from
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* the process to the kernel.
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*/
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/*
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* Get the message of the device driver
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*/
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#define IOCTL_GET_MSG _IOR(MAJOR_NUM, 1, char *)
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/*
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* This IOCTL is used for output, to get the message
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* of the device driver. However, we still need the
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* buffer to place the message in to be input,
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* as it is allocated by the process.
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*/
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/*
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* Get the n'th byte of the message
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*/
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#define IOCTL_GET_NTH_BYTE _IOWR(MAJOR_NUM, 2, int)
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/*
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* The IOCTL is used for both input and output. It
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* receives from the user a number, n, and returns
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* Message[n].
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*/
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/*
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* The name of the device file
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*/
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#define DEVICE_FILE_NAME "char_dev"
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#endif
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