Re: irq

["Sébastien Chrétien" <sebastien.chretien.enseirb@gmail.com>]

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I read the booting_without_of.txt document and the Interrupt Mapping
docucument from http://playground.sun.com/1275. But I don't understand all
parameters. Can somebody help me to create my device tree about interrupt
part ?

I have an interrupt controller at the adresse 0x20006000. The irq_id range
is 1 to 63.
I would like to try UART interrupt, which have ids : 0x18 (tranmission fifo
empty,
0x19 (reception fifo full), 0x1a (reception error), 0x1b (break emission).
What other informations are needed ?


Nothing is cascaded.

Thanks




2008/9/4, Benjamin Herrenschmidt <benh@kernel.crashing.org>:
>
> On Wed, 2008-09-03 at 23:02 +0200, Sébastien Chrétien wrote:
>
> > irq_of_parse_and_map is equivalent to ioremap in the MMU case ?
>
>
> On the powerpc architecture, we use virtualized IRQ numbers in order to
> deal with the wide range of interrupt controllers around and multiple
> of them cascaded.
>
> The base function to "map" a physical interrupt to a virtual interrupt
> is irq_create_mapping(). It takes an irq_host argument which represent
> the IRQ "domain" (typically irq controller) off which the interrupt you
> are trying to map hangs.
>
> If you pass NULL, it will use the "default" controller, which doesn't
> always exist, it depends on the platform. Usually, platforms set that
> to the toplevel PIC.
>
> However, normally, that function shouldn't be used directly. Instead,
> you should create a representation of your device in the device-tree
> along with the appropriate interrupt mapping, and then use the
> irq_of_parse_and_map() function to obtain a mapped virtual irq based
> on the device-tree information. This will take care of finding the
> right irq_host but will also properly setup the polarity of the
> interrupt etc...
>
> Now, as to how you should represent the interrupt in the device-tree,
> this should be explained in Documentation/booting-without-of.txt
>
> Cheers,
> Ben.
>
>

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