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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Tue, 16 Feb 2021 10:41:11 +0100
Message-ID: <CAK8P3a3rGurSQBubZ8i4+OHpDgM8mOfXiC6UhDYmL0MSQK4BRA@mail.gmail.com>
Subject: Re: [PATCH v2 14/25] dt-bindings: interrupt-controller: Add DT
 bindings for apple-aic
To:     Hector Martin <marcan@marcan.st>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Marc Zyngier <maz@kernel.org>, Rob Herring <robh@kernel.org>,
        Olof Johansson <olof@lixom.net>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Mark Kettenis <mark.kettenis@xs4all.nl>,
        Tony Lindgren <tony@atomide.com>,
        Mohamed Mediouni <mohamed.mediouni@caramail.com>,
        Stan Skowronek <stan@corellium.com>,
        Alexander Graf <graf@amazon.com>,
        Will Deacon <will@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Mark Rutland <mark.rutland@arm.com>,
        DTML <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Mon, Feb 15, 2021 at 1:17 PM Hector Martin <marcan@marcan.st> wrote:
> +
> +      The 2nd cell contains the interrupt number.
> +        - HW IRQs: interrupt number
> +        - FIQs:
> +          - 0: physical HV timer
> +          - 1: virtual HV timer
> +          - 2: physical guest timer
> +          - 3: virtual guest timer

I wonder if you could just model the FIQ as a single shared level interrupt
(which is essentially what it is), and have every driver that uses it do a
request_irq() on the same IRQ number.

This would avoid having to come up with a fake binding for it, and simplify
the implementation that then no longer has to peek into each interrupt
source.

     Arnd