dt-bindings: net: cpsw: Document cpsw-phy-sel usage but prefer phandle

The current cpsw usage for cpsw-phy-sel is undocumented but is used for
all the boards using cpsw. And cpsw-phy-sel is not really a child of
the cpsw device, it lives in the system control module instead.

Let's document the existing usage, and improve it a bit where we prefer
to use a phandle instead of a child device for it. That way we can
properly describe the hardware in dts files for things like genpd.

Cc: [email protected]
Cc: Andrew Lunn <[email protected]>
Cc: Grygorii Strashko <[email protected]>
Cc: Ivan Khoronzhuk <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Murali Karicheri <[email protected]>
Cc: Rob Herring <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: tmlind

Documentation/devicetree/bindings/net/cpsw.txt

@@ -19,6 +19,10 @@ Required properties:
 - slaves		: Specifies number for slaves
 - active_slave		: Specifies the slave to use for time stamping,
 			  ethtool and SIOCGMIIPHY
+- cpsw-phy-sel		: Specifies the phandle to the CPSW phy mode selection
+			  device. See also cpsw-phy-sel.txt for it's binding.
+			  Note that in legacy cases cpsw-phy-sel may be
+			  a child device instead of a phandle.
 
 Optional properties:
 - ti,hwmods		: Must be "cpgmac0"
@@ -75,6 +79,7 @@ Examples:
 		cpts_clock_mult = <0x80000000>;
 		cpts_clock_shift = <29>;
 		syscon = <&cm>;
+		cpsw-phy-sel = <&phy_sel>;
 		cpsw_emac0: slave@0 {
 			phy_id = <&davinci_mdio>, <0>;
 			phy-mode = "rgmii-txid";
@@ -103,6 +108,7 @@ Examples:
 		cpts_clock_mult = <0x80000000>;
 		cpts_clock_shift = <29>;
 		syscon = <&cm>;
+		cpsw-phy-sel = <&phy_sel>;
 		cpsw_emac0: slave@0 {
 			phy_id = <&davinci_mdio>, <0>;
 			phy-mode = "rgmii-txid";