b053dc5a72
Split device tree binding out of booting-without-of.txt and put them into their own files per binding. Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
50 lines
1.4 KiB
Text
50 lines
1.4 KiB
Text
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;
|
|
};
|
|
|
|
|