Interfacing a user program to a custom driver

["David Wooff" <David.Wooff@xxxxxxxxxx>]

I am in the process of creating a driver to interface to a custom FPGA on an in house AT91SAM9G20 board (based on the dev kit).

 

So far, I have created a driver module which at the moment doesn't do an awful lot other than request the I/O memory region associated with the chip select we are going to use.  This has been compiled into the kernel source tree and initialises by simply printing a message to say it has acquired the I/O memory region.

 

Now I want to write a user program to access the FPGA in order to test the interface.  My question is: how do I compile this and what does it actually link against i.e. do I simply add my driver module to the list of objects in the makefile for my user program?

 

Is there a standard way to do this or could someone provide an example?

 

Also, I guess I am a bit confused as to where the boundary between the user space and the kernel space actually is.  I mean, if the interface functions for the driver are in the driver module, then what stops the application program from simply accessing the FPGA directly?

 

I have read "Linux Device Drivers" but it uses a char driver as the main example so it doesn't help much in my case.

 

Regards,

Dave W.

 

 

 

David Wooff
Software Development Engineer
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