[PATCH 2/4] dt-bindings: gpio: add raspberry pi GPIO expander binding
From: baruch@tkos.co.il (Baruch Siach)
Date: 2018-01-02 13:19:19
Also in:
linux-devicetree, linux-gpio
Subsystem:
gpio subsystem, open firmware and flattened device tree bindings, the rest · Maintainers:
Linus Walleij, Bartosz Golaszewski, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds
The Raspberry Pi 3 GPIO expander is controlled by the VC4 firmware over I2C. The firmware mailbox interface allows the ARM core to control the GPIO lines. Signed-off-by: Baruch Siach <baruch@tkos.co.il> --- .../bindings/gpio/brcm,bcm2835-expgpio.txt | 24 ++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/brcm,bcm2835-expgpio.txt
diff --git a/Documentation/devicetree/bindings/gpio/brcm,bcm2835-expgpio.txt b/Documentation/devicetree/bindings/gpio/brcm,bcm2835-expgpio.txt
new file mode 100644
index 000000000000..55257f31a9be
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/brcm,bcm2835-expgpio.txt@@ -0,0 +1,24 @@ +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. + +Required properties: + +- compatible : Should be "brcm,bcm2835-expgpio" +- 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 +- firmware : Reference to the RPi firmware device node + +Example: + +expgpio: expgpio { + compatible = "brcm,bcm2835-expgpio"; + gpio-controller; + #gpio-cells = <2>; + firmware = <&firmware>; +};
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2.15.1