Basic PCI driver questions

Medeiros Edward M NPRI <MedeirosEM@xxxxxxxxxxxxxxxxx> · Fri, 06 Jan 2006 17:48:11 -0500

Hello All,

I have been reading the  "Linux Device Drivers"
book 3^rd edition but I'm not sure how to put it all together. 
I am writing a PCI device driver for a PCI board that is capable of DMA and
generating interrupts.  Here are my questions:

 Is a PCI driver always the best choice for a PCI board? 
     Why not write a "block" driver or a "char" driver?

2.   Is there a mechanism
for a user-space process to control/access  a PCI driver like the "ioctl"
call for a char driver?

 I mentioned that my board does DMA.  I am calling "pci_alloc_consistent()" 
     in my "probe()" function to allow my board to DMA data into a
     kernel space buffer.

Then I assume that I need to call a
function something like "move_to_user()" to pass the data to
user-space for processing.  Is there a way to DMA directly to user-space
without double buffering?

      4.  How can I alert a
user-space process when there is new data available from the PCI board?  
I was looking at the "top half" and "bottom half" 
sections in the 

          driver
book and contemplating using a "bottom half" process to move the
data to user-space but I don't know how to alert a user-space process it
has 

          new
data in its buffer to process.    What about
synchronization?   Could the function "wait_event_interruptable()" 
play a role here?

     5.  Has anyone done this
before?  Is there example driver source code that I might have
overlooked?  