Quoting Rob Herring (2020-02-25 10:16:54)

On Mon, Feb 24, 2020 at 10:06:08AM +0100, Maxime Ripard wrote:

quoted

The firmare running on the RPi VideoCore can be used to discover and
change the various clocks running in the BCM2711. Since devices will
need to use them through the DT, let's add a pretty simple binding.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-clk@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Maxime Ripard <redacted>
---
 Documentation/devicetree/bindings/clock/raspberrypi,firmware-clocks.yaml | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/raspberrypi,firmware-clocks.yaml

diff --git a/Documentation/devicetree/bindings/clock/raspberrypi,firmware-clocks.yaml b/Documentation/devicetree/bindings/clock/raspberrypi,firmware-clocks.yaml
new file mode 100644
index 000000000000..d37bc311321d
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/raspberrypi,firmware-clocks.yaml

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/raspberrypi,firmware-clocks.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RaspberryPi Firmware Clocks Device Tree Bindings
+
+maintainers:
+  - Maxime Ripard <mripard@kernel.org>
+
+properties:
+  "#clock-cells":
+    const: 1
+
+  compatible:
+    const: raspberrypi,firmware-clocks
+
+  raspberrypi,firmware:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: >
+      Phandle to the mailbox node to communicate with the firmware.

Can't this be a child node of the phandle instead? Or just add 
'#clock-cells' to the firmware node.

Yeah, just add the clock-cells to the firmware node unless that doesn't
work for some reason?