stacked driver communication

[Frank Hoeft]

Hi,

Stacked driver communication (kernel 2.2.20):

I wrote stacked driver moduls for an measurement system.
The lower driver handles the access to the pci-card.
This pci-card controls a bus-system , like iee488 for example.
This bus controls serveral at96-measurements-cards.
So the upper moduls control these different cards.

If the lower modul receive (from pci-card) an interrupt ,it 
have to  address the corresponding upper modul-isr.
So ,that moduls can read his registers.

I have solve this by ...
The upper modul registered the address from his isr
(and his at96-irq) in the lower modul.
The lower modul can detect wich at96-irq are requested.
The lower modul-isr  jumps in the corresponding 
upper module-isr, can fetch the data and wake up the
process.

I know the possibility to make it with EXPORT_SYMBOL
and use it to access from serveral 
upper-moduls to the lower-modul.

My question is:

It is possible to make this - or doubtful ... , 
if I make it secure (with corresponding 
register- an unregister- functions) that no 
pointer is standing in the wood.  

Best regards Frank Hoeft