Re: Changes to gt64260 interrupt support code

On Thu, Dec 27, 2001 at 12:44:24PM -0500, mod+linuxppc-dev@MissionCriticalLinux.com wrote:

Please introduce these changes into the linuxppc
sources in order that the existing gt64260 interrupt
support code be usable on platforms other than the
Galileo Eval Board.

The current gt64260 interrupt support code forces
use of particular Linux irqs (starting from 0) for
particular GT64260 interrupt sources.  These changes
allow use of that support code in other platforms and
(of particular interest in my situation) in combination
with other interrupt controllers (like the elegant
and flexible 8259) that also want to map *their*
interrupt sources to the Linux irqs starting at 0...

Ugh. Did I mention I hate 8259's?

We **REALLY** need a better way to deal with cascaded 8259's than adding
an offset.. I think Dan Malek had some good ideas on what to do about
this, but I don't know that anyone has got any currently running code that
solves this problem nicely.



--
Troy Benjegerdes | master of mispeeling | 'da hozer' |  hozer@drgw.net
-----"If this message isn't misspelled, I didn't write it" -- Me -----
"Why do musicians compose symphonies and poets write poems? They do it
because life wouldn't have any meaning for them if they didn't. That's
why I draw cartoons. It's my life." -- Charles Schulz

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On Wed, Jan 02, 2002 at 12:30:46PM -0600, Troy Benjegerdes wrote:

We **REALLY** need a better way to deal with cascaded 8259's than adding
an offset.. I think Dan Malek had some good ideas on what to do about
this, but I don't know that anyone has got any currently running code that
solves this problem nicely.

The ppc64 port has an array of virtual irq's which is used to index to the
real irq. In the interests of easy debugging (eg when drivers print out their
irq number) the virtual irq is kept identical to the actual whenever possible.

arch/ppc64/prom.c sets up the map (virt_irq_to_real_map), and
arch/ppc64/xics.c (the interrupt controller) uses it.

-Hollis

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