i have a D flip flop whose data lines are from the PPC controller and it is controlled through one of the chip selects.(CS4).
i have assigned the address on the CS4 and writing the value. From the u-boot it is happening but from the kernel when i try to acess the same area, the result is
Oops: kernel bad access of the area.
Can anyone please tell why this is happening. i m stuck with this problem for last 1 week.
How you are mapping the device? on a real physical memory location?
If so is there a method to separate this location from from being managed by memory manager?
if you are allocating a Virtual memory how you are doing it?
If I am not wrong then
1) the IO address should be mapped to a physical memory.
2) the VMM uses a reflection kind of thing like physmem 100x = vmm translate+1000x
have you tried that?
Next look into some legacy driver code, You will get a very good Idea from there.