Re: [PATCH 2/4] dt-bindings: gpio: add raspberry pi GPIO expander binding
From: Stefan Wahren <hidden>
Date: 2018-01-02 18:26:00
Also in:
linux-arm-kernel, linux-gpio
Hi Baruch,
quoted hunk ↗ jump to hunk
Baruch Siach [off-list ref] hat am 2. Januar 2018 um 14:19 geschrieben: 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.txtdiff --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"
from my understand this driver is specific to the Raspberry Pi and it's vendor is the Raspberry Pi Foundation. So i prefer Eric's suggestion of "raspberrypi,firmware-gpio", which also applies to the filename.
+- 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>;
+};
--
2.15.1
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