On Wed, Feb 07, 2018 at 08:35:23PM +0200, Baruch Siach wrote:
> 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@xxxxxxxxxx>
> ---
> v4:
> * Move the example gpio node under the firmware node
> * Rename gpio node name to plain 'gpio'
>
> v3:
> * Rename node name.
>
> v2:
> * Rename compatible string to raspberrypi,firmware-gpio
> ---
> .../bindings/gpio/raspberrypi,firmware-gpio.txt | 29 ++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/gpio/raspberrypi,firmware-gpio.txt
>
> 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..30326528faa9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/raspberrypi,firmware-gpio.txt
> @@ -0,0 +1,29 @@
> +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 "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
> +- firmware : Reference to the RPi firmware device node
This is the parent node. You don't need it.
> +
> +Example:
> +
> +firmware: firmware {
> + compatible = "raspberrypi,bcm2835-firmware";
> + mboxes = <&mailbox>;
No, sorry. /firmware is the container of firmware nodes. So
something like this:
firmware {
rpi-firmware {
compatible = "raspberrypi,bcm2835-firmware";
mboxes = <&mailbox>;
gpio {
compatible = "raspberrypi,firmware-gpio";
};
};
};
> +
> + expgpio: gpio {
> + compatible = "raspberrypi,firmware-gpio";
> + gpio-controller;
> + #gpio-cells = <2>;
> + firmware = <&firmware>;
> + };
> +};
> --
> 2.15.1
>
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