[RFC PATCH] dt-bindings: net: ethernet-controller: Add ptimer_handle

[Sarath Babu Naidu Gaddam]

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

ptimer_handle property will contain phandle to PTP timer node.

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 timer node, instead of
creating seperate property names in each ethernet driver DT node.

axiethernet driver uses this method when PTP support is integrated.

Example:
	fman0: fman@1a00000 {
		ptimer-handle = <&ptp_timer0>;
	}

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

Signed-off-by: Sarath Babu Naidu Gaddam <sarath.babu.naidu.gaddam@xxxxxxx>
---
We want binding to be reviewed/accepted and then make changes in freescale
binding documentation to use this generic binding.

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

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
tree/Documentation/devicetree/bindings/net/fsl-fman.txt#n320

Freescale driver:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
tree/drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c#n467

Changes in V2:
1)Added links to reference code snippets.
2)Updated commit msg.

Comments, suggestions and thoughts to have a common name are very welcome...!
---
 .../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 4b3c590fcebf..7e726d620c6a 100644
--- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
@@ -155,6 +155,11 @@ properties:
       - auto
       - in-band-status
 
+  ptimer_handle:
+    $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