LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Florian Fainelli <f.fainelli@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Rob Herring <robh+dt@kernel.org>
Cc: linux-tegra@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: Multi-parent IRQ domains
Date: Thu, 13 Sep 2018 14:50:21 -0700
Message-ID: <ea9261a9-2c4d-7ca4-6dca-73f385aa46d5@gmail.com> (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.
-- 
Florian

  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

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=ea9261a9-2c4d-7ca4-6dca-73f385aa46d5@gmail.com \
    --to=f.fainelli@gmail.com \
    --cc=devicetree@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tegra@vger.kernel.org \
    --cc=marc.zyngier@arm.com \
    --cc=robh+dt@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=thierry.reding@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox