51 lines
1.4 KiB
Plaintext
51 lines
1.4 KiB
Plaintext
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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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