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50 lines
1.5 KiB
C
50 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 they need
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* to be known both to the kernel module (in chardev.c) and the process
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* 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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/* The major device number. We can not rely on dynamic registration
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* any more, because ioctls need to know it.
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*/
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#define MAJOR_NUM 100
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/* Set the message of the device driver */
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#define IOCTL_SET_MSG _IOW(MAJOR_NUM, 0, char *)
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/* _IOW means that we are creating an ioctl command number for passing
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* information from a user process to the kernel module.
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*
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* The first arguments, MAJOR_NUM, is the major device number we are using.
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*
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* The second argument is the number of the command (there could be several
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* with different meanings).
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*
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* The third argument is the type we want to get from the process to the
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* kernel.
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*/
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/* Get the message of the device driver */
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#define IOCTL_GET_MSG _IOR(MAJOR_NUM, 1, char *)
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/* This IOCTL is used for output, to get the message of the device driver.
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* However, we still need the 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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/* Get the n'th byte of the message */
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#define IOCTL_GET_NTH_BYTE _IOWR(MAJOR_NUM, 2, int)
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/* The IOCTL is used for both input and output. It receives from the user
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* a number, n, and returns Message[n].
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*/
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/* The name of the device file */
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#define DEVICE_FILE_NAME "char_dev"
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#endif
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