usbphyc provides a unique clock called ck_usbo_48m.
STM32 USB OTG needs a 48Mhz clock (utmifs_clk48) for Full-Speed operation.
ck_usbo_48m is a possible parent clock for USB OTG 48Mhz clock.

ck_usbo_48m is available as soon as the PLL is enabled.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Acked-by: Rob Herring <robh@kernel.org>
---
Changes in v3:
- add Rob's Acked-by
- remove #clock-cells from required properties
---
 Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml b/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml
index 46df6786727a..018cc1246ee1 100644
--- a/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml
+++ b/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml

@@ -51,6 +51,10 @@ properties:
   vdda1v8-supply:
     description: regulator providing 1V8 power supply to the PLL block
 
+  '#clock-cells':
+    description: number of clock cells for ck_usbo_48m consumer
+    const: 0
+
 #Required child nodes:
 
 patternProperties:

@@ -120,6 +124,7 @@ examples:
         vdda1v8-supply = <&reg18>;
         #address-cells = <1>;
         #size-cells = <0>;
+        #clock-cells = <0>;
 
         usbphyc_port0: usb-phy@0 {
             reg = <0>;

-- 
2.17.1