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| -rw-r--r-- | Documentation/devicetree/bindings/gpio/raspberrypi,firmware-gpio.txt | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/gpio/raspberrypi,firmware-gpio.txt b/Documentation/devicetree/bindings/gpio/raspberrypi,firmware-gpio.txt new file mode 100644 index 000000000000..ce97265e23ba --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/raspberrypi,firmware-gpio.txt @@ -0,0 +1,30 @@ +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>; + }; +}; |