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Date: Wed, 19 Sep 2012 10:45:02 -0500
From: Rob Herring <robherring2@...il.com>
To: Thierry Reding <thierry.reding@...onic-design.de>
CC: devicetree-discuss@...ts.ozlabs.org,
Linus Walleij <linus.walleij@...ricsson.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt: Document general interrupt controller bindings
On 09/19/2012 03:57 AM, Thierry Reding wrote:
> In order to use a device as interrupt controller, it needs to be marked
> with the DT interrupt-controller property. This commit adds rudimentary
> documentation about the required standard properties and describes the
> most commonly used interrupt specifiers.
>
> Cc: Linus Walleij <linus.walleij@...ricsson.com>
> Cc: Grant Likely <grant.likely@...retlab.ca>
> Cc: Rob Herring <rob.herring@...xeda.com>
> Cc: devicetree-discuss@...ts.ozlabs.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Thierry Reding <thierry.reding@...onic-design.de>
> ---
> This patch is for Rob's tree as it documents the general bindings.
>
> .../bindings/interrupt-controller/interrupts.txt | 94 ++++++++++++++++++++++
> 1 file changed, 94 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
>
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt b/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
> new file mode 100644
> index 0000000..6cafe3a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
> @@ -0,0 +1,94 @@
> +Specifying interrupt information for devices
> +============================================
> +
> +1) Interrupt user nodes
> +-----------------------
> +
> +A device that generates interrupts can specify the interrupt controller to
> +which the interrupts are routed by passing the controller's phandle in the
> +"interrupt-parent" property.
> +
> +The "interrupts" property is a list of specifiers that describe each of the
> +interrupts. See section 2 below for details.
> +
> +2) Interrupt controller nodes
> +-----------------------------
> +
> +A device is marked as an interrupt controller with the "interrupt-controller"
> +property. This is a empty, boolean property. An additional "#interrupt-cells"
> +property defines the number of cells needed to specify a single interrupt.
> +
> +It is the responsibility of the interrupt controller's binding to define the
> +length and format of the interrupt specifier. The following two variants are
> +commonly used:
> +
> + a) one cell
> + -----------
> + The #interrupt-cells property is set to 1 and the single cell defines the
> + index of the interrupt within the controller.
> +
> + Example:
> +
> + vic: intc@...40000 {
> + compatible = "arm,versatile-vic";
> + interrupt-controller;
> + #interrupt-cells = <1>;
> + reg = <0x10140000 0x1000>;
> + };
> +
> + sic: intc@...03000 {
> + compatible = "arm,versatile-sic";
> + interrupt-controller;
> + #interrupt-cells = <1>;
> + reg = <0x10003000 0x1000>;
> + interrupt-parent = <&vic>;
> + interrupts = <31>; /* Cascaded to vic */
> + };
> +
> + b) two cells
> + ------------
> + The #interrupt-cells property is set to 2 and the first cell defines the
> + index of the interrupt within the controller, while the second cell is used
> + to specify any of the following flags:
> + - bits[3:0] trigger type and level flags
> + 1 = low-to-high edge triggered
> + 2 = high-to-low edge triggered
> + 4 = active high level-sensitive
> + 8 = active low level-sensitive
> +
> + Example:
> +
> + gpio: gpio {
> + compatible = "nvidia,tegra20-gpio";
> + reg = <0x6000d000 0x1000>;
> + interrupts = <0 32 0x04
> + 0 33 0x04
> + 0 34 0x04
> + 0 35 0x04
> + 0 55 0x04
> + 0 87 0x04
> + 0 89 0x04>;
Might be better to have an example where the parent here also follows
the documentation. There's no reason this needs to match a real binding,
so you could just drop the 1st cell.
Otherwise, I'll wait for Stephen to comment before I pick it up.
Rob
> + #gpio-cells = <2>;
> + gpio-controller;
> + #interrupt-cells = <2>;
> + interrupt-controller;
> + };
> +
> + i2c@...0c000 {
> + status = "okay";
> + clock-frequency = <400000>;
> +
> + wm8903: wm8903@1a {
> + compatible = "wlf,wm8903";
> + reg = <0x1a>;
> + interrupt-parent = <&gpio>;
> + interrupts = <187 0x04>;
> +
> + gpio-controller;
> + #gpio-cells = <2>;
> +
> + micdet-cfg = <0>;
> + micdet-delay = <100>;
> + gpio-cfg = <0xffffffff 0xffffffff 0 0xffffffff 0xffffffff>;
> + };
> + };
>
--
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