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Date:   Sat, 06 Oct 2018 11:02:50 +0100
Message-ID: <86tvlztmt1.wl-marc.zyngier@arm.com>
From:   Marc Zyngier <marc.zyngier@arm.com>
To:     Lokesh Vutla <lokeshvutla@ti.com>
Cc:     Nishanth Menon <nm@ti.com>, Tero Kristo <t-kristo@ti.com>,
        <tglx@linutronix.de>, <jason@lakedaemon.net>,
        Rob Herring <robh+dt@kernel.org>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Device Tree Mailing List <devicetree@vger.kernel.org>,
        Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, Sekhar Nori <nsekhar@ti.com>
Subject: Re: [PATCH 1/2] dt-bindings: irqchip: Introduce TISCI Interrupt router bindings
In-Reply-To: <20181006072812.15814-2-lokeshvutla@ti.com>
References: <20181006072812.15814-1-lokeshvutla@ti.com>
        <20181006072812.15814-2-lokeshvutla@ti.com>
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On Sat, 06 Oct 2018 08:28:11 +0100,
Lokesh Vutla <lokeshvutla@ti.com> wrote:
> 
> Add the DT binding documentation for Interrupt router driver.
> 
> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
> ---
>  .../interrupt-controller/ti,sci-intr.txt      | 83 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 84 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
> 
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt b/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
> new file mode 100644
> index 000000000000..681ca53cc5fb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
> @@ -0,0 +1,83 @@
> +Texas Instruments K3 Interrupt Router
> +=====================================
> +
> +The Interrupt Router (INTR) module provides a mechanism to mux M
> +interrupt inputs to N interrupt outputs, where all M inputs are selectable
> +to be driven per N output. There is one register per output (MUXCNTL_N) that
> +controls the selection.
> +
> +
> +                                 Interrupt Router
> +                             +----------------------+
> +                             |  Inputs     Outputs  |
> +        +-------+            | +------+             |
> +        | GPIO  |----------->| | irq0 |             |       Host IRQ
> +        +-------+            | +------+             |      controller
> +                             |    .        +-----+  |      +-------+
> +        +-------+            |    .        |  0  |  |----->|  GIC  |
> +        | INTA  |----------->|    .        +-----+  |      +-------+
> +        +-------+            |    .          .      |
> +                             | +------+      .      |
> +                             | | irqM |    +-----+  |
> +                             | +------+    |  N  |  |
> +                             |             +-----+  |
> +                             +----------------------+
> +
> +Configuration of these MUXCNTL_N registers is done by a system controller
> +(like the Device Memory and Security Controller on K3 AM654 SoC). System
> +controller will keep track of the used and unused registers within the Router.
> +Driver should request the system controller to get the range of GIC IRQs
> +assigned to the requesting hosts. It is the drivers responsibility to keep
> +track of GIC IRQs.

I would drop the GIC here, and replace it by "parent interrupt
controller", as nothing here is GIC specific.

> +
> +Communication between the host processor running an OS and the system
> +controller happens through a protocol called TI System Control Interface
> +(TISCI protocol). For more details refer:
> +Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
> +
> +TISCI Interrupt Router Node:
> +----------------------------
> +- compatible:		Must be "ti,sci-intr".
> +- interrupt-controller:	Identifies the node as an interrupt controller
> +- #interrupt-cells:	Specifies the number of cells needed to encode an
> +			interrupt source. The value should be 3.
> +			First cell should contain the TISCI device ID of source
> +			Second cell should contain the interrupt source offset
> +			within the device
> +			Third cell specifies the trigger type as defined
> +			in interrupts.txt in this directory.

Are all trigger types supported?

> +- interrupt-parent:	phandle of irq parent for TISCI intr. The parent must
> +			use the same interrupt-cells format as GIC.

Why that constraint? From what I can see, the two are fairly
independent, and the constraint looks more of a Linux driver issue
than a DT constraint.

> +- ti,sci:		Phandle to TI-SCI compatible System controller node.
> +- ti,sci-dst-id:	TISCI device ID of the destination IRQ controller.
> +- ti,sci-rm-range-girq:	Tuple corresponding to unique TISCI resource type that
> +			defines the dst host irq ranges assigned to this
> +			interrupt router from this host context.
> +			Tuple should be of format <type subtype>.
> +
> +Example:
> +--------
> +The following example demonstrates both interrupt router node and the consumer
> +node(main gpio) on the AM654 SoC:
> +
> +main_intr: interrupt-controller@1 {
> +	compatible = "ti,sci-intr";
> +	interrupt-controller;
> +	interrupt-parent = <&gic>;
> +	#interrupt-cells = <3>;
> +	ti,sci = <&dmsc>;
> +	ti,sci-dst-id = <56>;
> +	ti,sci-rm-range-girq = <0xb 0x1>;
> +};
> +
> +main_gpio0:  main_gpio0@600000 {
> +	...
> +	interrupt-parent = <&main_intr>;
> +	interrupts = <57 256 IRQ_TYPE_EDGE_RISING>,
> +			<57 257 IRQ_TYPE_EDGE_RISING>,
> +			<57 258 IRQ_TYPE_EDGE_RISING>,
> +			<57 259 IRQ_TYPE_EDGE_RISING>,
> +			<57 260 IRQ_TYPE_EDGE_RISING>,
> +			<57 261 IRQ_TYPE_EDGE_RISING>;
> +	...
> +};
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 29c08106bd22..a23778b68d74 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14625,6 +14625,7 @@ F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
>  F:	Documentation/devicetree/bindings/clock/ti,sci-clk.txt
>  F:	drivers/clk/keystone/sci-clk.c
>  F:	drivers/reset/reset-ti-sci.c
> +F:	Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
>  
>  THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
>  M:	Hans Verkuil <hverkuil@xs4all.nl>
> -- 
> 2.19.0
> 

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.