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Subject: Re: [PATCH v4 00/13] Add support for TISCI irqchip drivers
To:     <marc.zyngier@arm.com>, Nishanth Menon <nm@ti.com>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Rob Herring <robh+dt@kernel.org>, <tglx@linutronix.de>,
        <jason@lakedaemon.net>
CC:     Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, Tero Kristo <t-kristo@ti.com>,
        Sekhar Nori <nsekhar@ti.com>,
        Device Tree Mailing List <devicetree@vger.kernel.org>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>
References: <20181227060829.5080-1-lokeshvutla@ti.com>
From:   Lokesh Vutla <lokeshvutla@ti.com>
Message-ID: <620377f9-719f-0ce2-2b70-87fb6aa5d764@ti.com>
Date:   Fri, 11 Jan 2019 15:58:00 +0530
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Hi Marc,

On 27/12/18 11:38 AM, Lokesh Vutla wrote:
> TI AM65x SoC based on K3 architecture, introduced support for Events
> which are message based interrupts with minimal latency. These events
> are not compatible with regular interrupts and are valid only through
> an event transport lane. An Interrupt Aggregator(INTA) is introduced
> to convert these events to interrupts. INTA can also group 64 events
> into a single interrupt. Now the SoC has many peripherals and a large
> number of event sources (time sync or DMA), the use of events is
> completely dependent on a user's specific application, which drives a
> need for maximum flexibility in which event sources are used in the
> system. It is also completely up to software control as to how the
> events are serviced.
> 
> Because of the huge flexibility there are certain standard peripherals
> (like GPIO etc)where all interrupts cannot be directly corrected to host
> interrupt controller. For this purpose, Interrupt Router(INTR) is
> introduced in the SoC. INTR just does a classic interrupt redirection.
> 
> So the SoC has 3 types of interrupt controllers:
> - GIC500
> - Interrupt Router
> - Interrupt Aggregator
> 
> Below is a diagrammatic view of how SoC integration of these interrupt
> controllers:(https://pastebin.ubuntu.com/p/9ngV3jdGj2/)
> 
> Device Index-x               Device Index-y
>            |                         |
>            |                         |
>                       ....
>             \                       /
>              \                     /
>               \  (global events)  /
>           +---------------------------+   +---------+
>           |                           |   |         |
>           |             INTA          |   |  GPIO   |
>           |                           |   |         |
>           +---------------------------+   +---------+
>                          |   (vint)            |
>                          |                     |
>                         \|/                    |
>           +---------------------------+        |
>           |                           |<-------+
>           |           INTR            |
>           |                           |
>           +---------------------------+
>                          |
>                          |
>                         \|/ (gic irq)
>           +---------------------------+
>           |                           |
>           |             GIC           |
>           |                           |
>           +---------------------------+


Can you please take a look at the MSI changes and provide your feedback? There
are few places(mentioned in the respective patches) where I felt I am hacking
around. It would be really helpful if you give any direction for such hacks.

Thanks and regards,
Lokesh