On Tue, Feb 20, 2018 at 1:34 AM, Baruch Siach [off-list ref] wrote:

Hi Rob,

Thanks again for reviewing.

On Tue, Feb 13, 2018 at 05:20:07PM -0600, Rob Herring wrote:

quoted

On Wed, Feb 07, 2018 at 08:35:23PM +0200, Baruch Siach wrote:

quoted

+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.

OK. I guess of_get_parent() will do the trick.

quoted

quoted

+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";

              };
      };
};

This is the hierarchy we currently have at arch/arm/boot/dts/bcm2835-rpi.dtsi:

/ {
        soc {
                firmware: firmware {
                        compatible = "raspberrypi,bcm2835-firmware";
                        mboxes = <&mailbox>;
                };
        };
};

Are you suggesting to add another container between 'soc' and 'firmware'? Or
is it the 'firmware' node name that we need to change to 'rpi-firmware'?

Ah, I guess RPi missed following putting its firmware node under a
/firmware node rather than under /soc. We try to put all firmware
interfaces (you can have more than one) under /firmware. So just as I
wrote out. But you don't need to change that for this.

Just noting this is a child of "raspberrypi,bcm2835-firmware" is enough.

Rob