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SubjectRe: [RFC PATCH 1/4] DRIVERS: IRQCHIP: Add crossbar irqchip driver
On Wednesday 18 September 2013 07:22 PM, Sricharan R wrote:
> Hi Thomas,
>
> On Tuesday 17 September 2013 05:56 PM, Linus Walleij wrote:
>> On Fri, Sep 13, 2013 at 4:24 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
>>
>>> So why can't you make use of irq domains and have the whole routing
>>> business implemented sanely?
>>>
>>> What's needed is in gic_init_bases():
>>> irq
>>> if (of_property_read(node, "routable_irqs", &nr_routable_irqs) {
>>> irq_domain_add_legacy(nr_gic_irqs);
>>> } else {
>>> irq_domain_add_legacy(nr_per_cpu_irqs);
>>> irq_domain_add_linear(nr_routable_irqs);
>>> }
>>>
>>> Now that separate domain has an xlate function which grabs a free GIC
>>> irq from a bitmap and returns the hardware irq number in the gic
>>> space. The map/unmap callbacks take care of setting up / tearing down
>>> the route in the crossbar.
>> This is obviously the right approach, it's exactly what .map should do
>> the only special thing here being that we have hardware to perform
>> the mapping ... bah why didn't I realize this :-(
>>
>> Yours,
>> Linus Walleij
> Thanks for the suggestion.
>
> So as i understand this, this implies using the GIC domain itself and
> add the support for dynamically routable irqs (like crossbar) with in the
> GIC driver itself right ?
Please ignore this. So the question was more of how to implement the
call outs in the case of routable irqs from map/ unmap callbacks.
I will look more here and come back.

Regards,
Sricharan



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