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From: Florian Fainelli <>
To: Thierry Reding <>,
	Marc Zyngier <>,
	Thomas Gleixner <>,
	Rob Herring <>
Subject: Re: Multi-parent IRQ domains
Date: Thu, 13 Sep 2018 14:50:21 -0700
Message-ID: <> (raw)
In-Reply-To: <20180913155945.GA19903@ulmo>

On 09/13/18 08:59, Thierry Reding wrote:
> Hi everyone,
> I've been trying to implement a feature on recent Tegra chips that's
> called "wake events". These wake events are implemented as part of the
> power management controller (PMC) and they control which events can be
> used to wake the system from suspend. Events include things like an
> alarm interrupt from an RTC, or the GPIO interrupt hooked up to a
> power button for example.
> We already have a driver for a couple of other things that the PMC does,
> so I thought it'd be natural to implement this functionality as an IRQ
> chip in the PMC driver. The way that this would work is that for all the
> devices that are wakeup sources, we'd end up specifying the PMC as the
> interrupt parent and the PMC would then itself have the main GIC as its
> parent. That way, the hierarchical IRQ domain infrastructure would take
> care of pretty much everything.
> Unfortunately I've run into some issues here. One problem that I'm
> facing is that PMC could have more than one parent. For example, the RTC
> alarm interrupt goes straight to the GIC, but the power button GPIO goes
> through the GPIO controller first and then to the GIC. This doesn't seem
> to be something that's currently possible.
> The way I imagine this to work from a DT perspective is as follows:

There is an interrupts-extended property which as a first cell takes a
phandle to the parent interrupt controller, e.g:

interrupts-extended = <&gic 73 GIPC_SPI IRQ_TYPE_LEVEL_HIGH>,
			<&pmc 10>;

(provided that I understood your problem and example correctly). We have
a similar use case on our STB chips where we have "main" interrupts
wired to the ARM GIC and wake-up interrupts wired to a specific wake-up
interrupt controller in an always-on domain. The two controllers have a
different #interrupt-cells specifier.

The interrupt infrastructure in Linux already knows how to deal with
that and whether you use of_get_irq() or platform_get_irq() you should
obtain the correct virtual interrupt numbers that you expected, parented
to the appropriate interrupt controller.

Hope this helps.

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-13 15:59 Thierry Reding
2018-09-13 21:50 ` Florian Fainelli [this message]
2018-09-14  8:10   ` Thierry Reding
2018-09-14 10:31 ` Thomas Gleixner
2018-09-17  9:52   ` Thierry Reding
2018-09-17 12:28     ` Thomas Gleixner
2018-09-17 13:07       ` Thierry Reding
2018-09-17 13:27         ` Thomas Gleixner
2018-09-14 10:44 ` Sudeep Holla

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