Re: Interrupt handling documentation

[Michael Ellerman <michael@ellerman.id.au>]

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On Tue, 2008-03-11 at 11:58 +0100, Laurent Pinchart wrote:
> Hi everybody,
> 
> is there any documentation describing interrupt handling for the powerpc 
> architecture ? I'm writing a driver for a cascaded interrupt controller and 
> the only source of information I found was the code.

I don't think there's much documentation.

You might want to look at arch/powerpc/platforms/cell/axon_msi.c, it's a
reasonably simple example of how to setup an irq_host and so on - well I
think so :D

> I'm particularly interested in information about irq hosts (allocation and 
> initialisation, especially the map and unmap callbacks) and irq chaining. 
> Different drivers seem to implement cascaded irqs differently (for instance 
> arch/powerpc/sysdev/uic.c uses setup_irq to register the cascaded irq 
> handler, while arch/powerpc/platforms/82xx/pq2ads-pci-pic.c uses 
> set_irq_chained_handler) so I'm a bit lost here.

uic.c uses set_irq_chained_handler() now, so that probably answers that
question. I don't think it makes all that much difference if you set it
up by hand, but set_irq_chained_handler() is the neat way to do it.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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