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[mirror_ubuntu-bionic-kernel.git] / Documentation / powerpc / dts-bindings / gpio / gpio.txt
1 Specifying GPIO information for devices
2 ============================================
3
4 1) gpios property
5 -----------------
6
7 Nodes that makes use of GPIOs should define them using `gpios' property,
8 format of which is: <&gpio-controller1-phandle gpio1-specifier
9 &gpio-controller2-phandle gpio2-specifier
10 0 /* holes are permitted, means no GPIO 3 */
11 &gpio-controller4-phandle gpio4-specifier
12 ...>;
13
14 Note that gpio-specifier length is controller dependent.
15
16 gpio-specifier may encode: bank, pin position inside the bank,
17 whether pin is open-drain and whether pin is logically inverted.
18
19 Example of the node using GPIOs:
20
21 node {
22 gpios = <&qe_pio_e 18 0>;
23 };
24
25 In this example gpio-specifier is "18 0" and encodes GPIO pin number,
26 and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller.
27
28 2) gpio-controller nodes
29 ------------------------
30
31 Every GPIO controller node must have #gpio-cells property defined,
32 this information will be used to translate gpio-specifiers.
33
34 Example of two SOC GPIO banks defined as gpio-controller nodes:
35
36 qe_pio_a: gpio-controller@1400 {
37 #gpio-cells = <2>;
38 compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
39 reg = <0x1400 0x18>;
40 gpio-controller;
41 };
42
43 qe_pio_e: gpio-controller@1460 {
44 #gpio-cells = <2>;
45 compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
46 reg = <0x1460 0x18>;
47 gpio-controller;
48 };
49
50