net: dsa: Allow multi hop routes to be expressed

With more than two switches in a hierarchy, it becomes necessary to
describe multi-hop routes between switches. The current binding does
not allow this, although the older platform_data did. Extend the link
property to be a list rather than a single phandle to a remote switch.
It is then possible to express that a port should be used to reach
more than one switch and the switch maybe more than one hop away.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 27 insertions, 6 deletions

diff --git a/Documentation/devicetree/bindings/net/dsa/dsa.txt b/Documentation/devicetree/bindings/net/dsa/dsa.txt
index 9cf9a0ec333c..04e6bef3ac3f 100644
--- a/Documentation/devicetree/bindings/net/dsa/dsa.txt
+++ b/Documentation/devicetree/bindings/net/dsa/dsa.txt
@@ -44,9 +44,10 @@ Note that a port labelled "dsa" will imply checking for the uplink phandle
 described below.
 
 Optionnal property:
-- link			: Should be a phandle to another switch's DSA port.
+- link			: Should be a list of phandles to another switch's DSA port.
 			  This property is only used when switches are being
-			  chained/cascaded together.
+			  chained/cascaded together. This port is used as outgoing port
+			  towards the phandle port, which can be more than one hop away.
 
 - phy-handle		: Phandle to a PHY on an external MDIO bus, not the
 			  switch internal one. See
@@ -100,10 +101,11 @@ Example:
 				label = "cpu";
 			};
 
-			switch0uplink: port@6 {
+			switch0port6: port@6 {
 				reg = <6>;
 				label = "dsa";
-				link = <&switch1uplink>;
+				link = <&switch1port0
+				        &switch2port0>;
 			};
 		};
 
@@ -113,10 +115,29 @@ Example:
 			reg = <17 1>;	/* MDIO address 17, switch 1 in tree */
 			mii-bus = <&mii_bus1>;
 
-			switch1uplink: port@0 {
+			switch1port0: port@0 {
 				reg = <0>;
 				label = "dsa";
-				link = <&switch0uplink>;
+				link = <&switch0port6>;
+			};
+			switch1port1: port@1 {
+				reg = <1>;
+				label = "dsa";
+				link = <&switch2port1>;
+			};
+		};
+
+		switch@2 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			reg = <18 2>;	/* MDIO address 18, switch 2 in tree */
+			mii-bus = <&mii_bus1>;
+
+			switch2port0: port@0 {
+				reg = <0>;
+				label = "dsa";
+				link = <&switch1port1
+				        &switch0port6>;
 			};
 		};
 	};