On Tue, 2004-04-27 at 10:07, Claudio Fiorini wrote:
> Hi,
> I'm new to kernel hacking, I'm trying to devel a kernel module to use
> parallel port with simple led because i do in user-space, but now
> i want to do that in kernel-space.
> I start to read the linux device driver 2nd edition and I'm
> ok where i register a char device, but the book show
> me the file_operations struct that has many pointers functions
> this is what i do:
>
> struct file_operations *f_pport;
In my opinion, u need to define file operations and
then pass it over to the register_chrdev.
Eg:
struct file_operations f_pport {
.owner = THIS_MODULE,
.open = Your_open_function, /* U may refer any of the
* character device code
*/
.write = Your_write_function, /* Function pointer to do your
* function, LED write
*/
.read = Your_read_function, /* Function pointer to do your
* function, LED read
*/
...
}
> pport = register_chrdev(PPORT_MAJOR_NUMBER, PPORT_CONST_NAME,
> f_pport);
Here u are registering a char device using
the major number PPORT_MAJOR_NUMBER. Using this major number
u can make a character device with a minor number from
the userland. This can be done using command mknod.
>
> now if i want to open i have to do something like this?
> f_pport->open(struct inode *, struct file *);
I think u don't need to call the open function from the
kernel module. When u try to open the character device
file from userland after registration, it will be called
( kernel will do it ).
Similarly, when u write to the device file your write function
will be called. ( echo something > /dev/your_device )
>
> and in the book i don't understand which information i have
> to give to struct inode and struct file.
>
> Thanks
>
> Claudio
Regards,
Shine Mohamed Jabbar
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