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Specifying GPIO information for devices
============================================
1) gpios property
-----------------
Nodes that makes use of GPIOs should define them using `gpios' property,
format of which is: <&gpio-controller1-phandle gpio1-specifier
&gpio-controller2-phandle gpio2-specifier
0 /* holes are permitted, means no GPIO 3 */
&gpio-controller4-phandle gpio4-specifier
...>;
Note that gpio-specifier length is controller dependent.
gpio-specifier may encode: bank, pin position inside the bank,
whether pin is open-drain and whether pin is logically inverted.
Example of the node using GPIOs:
node {
gpios = <&qe_pio_e 18 0>;
};
In this example gpio-specifier is "18 0" and encodes GPIO pin number,
and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller.
2) gpio-controller nodes
------------------------
Every GPIO controller node must have #gpio-cells property defined,
this information will be used to translate gpio-specifiers.
Example of two SOC GPIO banks defined as gpio-controller nodes:
qe_pio_a: gpio-controller@1400 {
#gpio-cells = <2>;
compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
reg = <0x1400 0x18>;
gpio-controller;
};
qe_pio_e: gpio-controller@1460 {
#gpio-cells = <2>;
compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
reg = <0x1460 0x18>;
gpio-controller;
};
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