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Viewing changes to Documentation/powerpc/dts-bindings/gpio/gpio.txt

  • Committer: Bazaar Package Importer
  • Author(s): Luke Yelavich
  • Date: 2009-08-05 23:00:52 UTC
  • Revision ID: james.westby@ubuntu.com-20090805230052-7xedvqcyk9dnnxb2
Tags: 2.6.31-1.1
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Documentation/powerpc/dts-bindings/gpio/gpio.txt
 
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Specifying GPIO information for devices
 
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============================================
 
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1) gpios property
 
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-----------------
 
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Nodes that makes use of GPIOs should define them using `gpios' property,
 
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format of which is: <&gpio-controller1-phandle gpio1-specifier
 
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                     &gpio-controller2-phandle gpio2-specifier
 
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                     0 /* holes are permitted, means no GPIO 3 */
 
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                     &gpio-controller4-phandle gpio4-specifier
 
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                     ...>;
 
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Note that gpio-specifier length is controller dependent.
 
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gpio-specifier may encode: bank, pin position inside the bank,
 
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whether pin is open-drain and whether pin is logically inverted.
 
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Example of the node using GPIOs:
 
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        node {
 
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                gpios = <&qe_pio_e 18 0>;
 
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        };
 
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In this example gpio-specifier is "18 0" and encodes GPIO pin number,
 
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and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller.
 
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2) gpio-controller nodes
 
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------------------------
 
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Every GPIO controller node must have #gpio-cells property defined,
 
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this information will be used to translate gpio-specifiers.
 
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Example of two SOC GPIO banks defined as gpio-controller nodes:
 
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        qe_pio_a: gpio-controller@1400 {
 
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                #gpio-cells = <2>;
 
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                compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
 
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                reg = <0x1400 0x18>;
 
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                gpio-controller;
 
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        };
 
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        qe_pio_e: gpio-controller@1460 {
 
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                #gpio-cells = <2>;
 
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                compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
 
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                reg = <0x1460 0x18>;
 
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                gpio-controller;
 
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        };
 
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