[RFC] 85XX: Allow 8259 cascade to share an MPIC interrupt line.

[Jon Loeliger]

On Wed, 2007-06-06 at 19:47, Randy Vinson wrote:
> The Freescale MPC8555CDS and MPC8548CDS reference hardware has a legacy
> 8259 interrupt controller pair contained within a VIA VT82C686B Southbridge
> on the main carrier board. The processor complex plugs into the carrier
> card using a PCI slot which limits the available interrupts to the
> INTA-INTD PCI interrupts. The output of the 8259 cascade pair is routed
> through a gate array and connected to the PCI INTA interrupt line.
> The normal interrupt chaining hook (set_irq_chained_handler) does
> not allow sharing of the chained interrupt which prevents the
> use of PCI INTA by PCI devices. This patch allows the 8259 cascade
> pair to share their interrupt line with PCI devices.
> 
> Signed-off-by: Randy Vinson <rvinson at mvista.com>
> ---
> Note that there may very well be a better way of accomplishing this. If someone
> has a better alternative, I'm open to it. This was just the simplest way I could
> get this to work.
> 
> Also, the addition of the .end routine for the MPIC is not strictly necessary for
> this patch. It's there so this code will run from within the threaded interrupt
> context used by the Real Time patch.


Hmm.  I feel that at least the last paragraph here needs
to be above the --- line for future patch readers.  Otherwise
it's relationship to the rest of the patch details will be
intermixed and lost.

Thanks,
jdl