[PATCH net-next V3] dt-bindings: net: ethernet-controller: Add ptp-hardware-clock

[Sarath Babu Naidu Gaddam]

There is currently no standard property to pass PTP device index
information to ethernet driver when they are independent.

ptp-hardware-clock property will contain phandle to PTP clock node.

Its a generic (optional) property name to link to PTP phandle to
Ethernet node. Any future or current ethernet drivers that need
a reference to the PHC used on their system can simply use this
generic property name instead of using custom property
implementation in their device tree nodes."

Signed-off-by: Sarath Babu Naidu Gaddam <sarath.babu.naidu.gaddam@xxxxxxx>
Acked-by: Richard Cochran <richardcochran@xxxxxxxxx>
---

Freescale driver currently has this implementation but it will be
good to agree on a generic (optional) property name to link to PTP
phandle to Ethernet node. In future or any current ethernet driver
wants to use this method of reading the PHC index,they can simply use
this generic name and point their own PTP clock node, instead of
creating separate property names in each ethernet driver DT node.

axiethernet driver uses this method when PTP support is integrated.

Example:
    fman0: fman@1a00000 {
        ptp-hardware-clock = <&ptp_timer0>;
    }

    ptp_timer0: ptp-timer@1afe000 {
        compatible = "fsl,fman-ptp-timer";
        reg = <0x0 0x1afe000 0x0 0x1000>;
    }

DT information:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/freescale/qoriq-fman3-0.dtsi#n23

Freescale driver:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c#n407

Changes in V3:
1) Updated commit description.
2) Add Acked-by: Richard Cochran.

Changes in V2:
1) Changed the ptimer-handle to ptp-hardware-clock based on
   Richard Cochran's comment.
2) Updated commit description.
---
 .../devicetree/bindings/net/ethernet-controller.yaml         | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/ethernet-controller.yaml b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
index 00be387984ac..a97ab25b07a5 100644
--- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
@@ -161,6 +161,11 @@ properties:
       - auto
       - in-band-status
 
+  ptp-hardware-clock:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Specifies a reference to a node representing a IEEE1588 timer.
+
   fixed-link:
     oneOf:
       - $ref: /schemas/types.yaml#/definitions/uint32-array
-- 
2.25.1