a9ecdc0fdc
In case the Device Tree blob passed by the boot agent supplies both an 'interrupts-extended' and an 'interrupts' property in order to allow for older kernels to be usable, prefer the new-style 'interrupts-extended' property which conveys a lot more information. This allows us to have bootloaders willingly maintaining backwards compatibility with older kernels without entirely deprecating the 'interrupts' property. Update the bindings documentation to describe a situation where both the 'interrupts-extended' and the 'interrupts' property are present, and which one takes precedence over the other. Cc: stable@vger.kernel.org # 3.13+ Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Brian Norris <computersforpeace@gmail.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Grant Likely <grant.likely@linaro.org>
115 lines
3.5 KiB
Plaintext
115 lines
3.5 KiB
Plaintext
Specifying interrupt information for devices
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============================================
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1) Interrupt client nodes
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-------------------------
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Nodes that describe devices which generate interrupts must contain an
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"interrupts" property, an "interrupts-extended" property, or both. If both are
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present, the latter should take precedence; the former may be provided simply
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for compatibility with software that does not recognize the latter. These
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properties contain a list of interrupt specifiers, one per output interrupt. The
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format of the interrupt specifier is determined by the interrupt controller to
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which the interrupts are routed; see section 2 below for details.
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Example:
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interrupt-parent = <&intc1>;
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interrupts = <5 0>, <6 0>;
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The "interrupt-parent" property is used to specify the controller to which
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interrupts are routed and contains a single phandle referring to the interrupt
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controller node. This property is inherited, so it may be specified in an
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interrupt client node or in any of its parent nodes. Interrupts listed in the
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"interrupts" property are always in reference to the node's interrupt parent.
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The "interrupts-extended" property is a special form for use when a node needs
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to reference multiple interrupt parents. Each entry in this property contains
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both the parent phandle and the interrupt specifier. "interrupts-extended"
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should only be used when a device has multiple interrupt parents.
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Example:
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interrupts-extended = <&intc1 5 1>, <&intc2 1 0>;
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A device node may contain either "interrupts" or "interrupts-extended", but not
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both. If both properties are present, then the operating system should log an
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error and use only the data in "interrupts".
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2) Interrupt controller nodes
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-----------------------------
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A device is marked as an interrupt controller with the "interrupt-controller"
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property. This is a empty, boolean property. An additional "#interrupt-cells"
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property defines the number of cells needed to specify a single interrupt.
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It is the responsibility of the interrupt controller's binding to define the
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length and format of the interrupt specifier. The following two variants are
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commonly used:
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a) one cell
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-----------
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The #interrupt-cells property is set to 1 and the single cell defines the
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index of the interrupt within the controller.
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Example:
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vic: intc@10140000 {
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compatible = "arm,versatile-vic";
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interrupt-controller;
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#interrupt-cells = <1>;
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reg = <0x10140000 0x1000>;
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};
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sic: intc@10003000 {
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compatible = "arm,versatile-sic";
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interrupt-controller;
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#interrupt-cells = <1>;
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reg = <0x10003000 0x1000>;
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interrupt-parent = <&vic>;
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interrupts = <31>; /* Cascaded to vic */
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};
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b) two cells
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------------
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The #interrupt-cells property is set to 2 and the first cell defines the
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index of the interrupt within the controller, while the second cell is used
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to specify any of the following flags:
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- bits[3:0] trigger type and level flags
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1 = low-to-high edge triggered
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2 = high-to-low edge triggered
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4 = active high level-sensitive
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8 = active low level-sensitive
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Example:
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i2c@7000c000 {
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gpioext: gpio-adnp@41 {
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compatible = "ad,gpio-adnp";
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reg = <0x41>;
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interrupt-parent = <&gpio>;
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interrupts = <160 1>;
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gpio-controller;
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#gpio-cells = <1>;
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interrupt-controller;
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#interrupt-cells = <2>;
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nr-gpios = <64>;
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};
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sx8634@2b {
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compatible = "smtc,sx8634";
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reg = <0x2b>;
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interrupt-parent = <&gpioext>;
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interrupts = <3 0x8>;
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#address-cells = <1>;
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#size-cells = <0>;
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threshold = <0x40>;
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sensitivity = <7>;
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};
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};
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