mirror of https://gitee.com/openkylin/linux.git
31 lines
815 B
Plaintext
31 lines
815 B
Plaintext
Raspberry Pi GPIO expander
|
|
|
|
The Raspberry Pi 3 GPIO expander is controlled by the VC4 firmware. The
|
|
firmware exposes a mailbox interface that allows the ARM core to control the
|
|
GPIO lines on the expander.
|
|
|
|
The Raspberry Pi GPIO expander node must be a child node of the Raspberry Pi
|
|
firmware node.
|
|
|
|
Required properties:
|
|
|
|
- compatible : Should be "raspberrypi,firmware-gpio"
|
|
- gpio-controller : Marks the device node as a gpio controller
|
|
- #gpio-cells : Should be two. The first cell is the pin number, and
|
|
the second cell is used to specify the gpio polarity:
|
|
0 = active high
|
|
1 = active low
|
|
|
|
Example:
|
|
|
|
firmware: firmware-rpi {
|
|
compatible = "raspberrypi,bcm2835-firmware";
|
|
mboxes = <&mailbox>;
|
|
|
|
expgpio: gpio {
|
|
compatible = "raspberrypi,firmware-gpio";
|
|
gpio-controller;
|
|
#gpio-cells = <2>;
|
|
};
|
|
};
|