net: dsa: b53: Add support for Broadcom RoboSwitch

This patch adds support for Broadcom's BCM53xx switch family, also known
as RoboSwitch. Some of these switches are ubiquituous, found in home
routers, Wi-Fi routers, DSL and cable modem gateways and other
networking related products.

This drivers adds the library driver (b53_common.c) as well as a few bus
glue drivers for MDIO, SPI, Switch Register Access Block (SRAB) and
memory-mapped I/O into a SoC's address space (Broadcom BCM63xx/33xx).

Basic operations are supported to bring the Layer 1/2 up and running,
but not much more at this point, subsequent patches add the remaining
features.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/b53.txt

@@ -0,0 +1,88 @@
+Broadcom BCM53xx Ethernet switches
+==================================
+
+Required properties:
+
+- compatible: For external switch chips, compatible string must be exactly one
+  of: "brcm,bcm5325"
+      "brcm,bcm53115"
+      "brcm,bcm53125"
+      "brcm,bcm53128"
+      "brcm,bcm5365"
+      "brcm,bcm5395"
+      "brcm,bcm5397"
+      "brcm,bcm5398"
+
+  For the BCM5310x SoCs with an integrated switch, must be one of:
+      "brcm,bcm53010-srab"
+      "brcm,bcm53011-srab"
+      "brcm,bcm53012-srab"
+      "brcm,bcm53018-srab"
+      "brcm,bcm53019-srab" and the mandatory "brcm,bcm5301x-srab" string
+
+  For the BCM63xx/33xx SoCs with an integrated switch, must be one of:
+      "brcm,bcm3384-switch"
+      "brcm,bcm6328-switch"
+      "brcm,bcm6368-switch" and the mandatory "brcm,bcm63xx-switch"
+
+See Documentation/devicetree/bindings/dsa/dsa.txt for a list of additional
+required and optional properties.
+
+Examples:
+
+Ethernet switch connected via MDIO to the host, CPU port wired to eth0:
+
+	eth0: ethernet@10001000 {
+		compatible = "brcm,unimac";
+		reg = <0x10001000 0x1000>;
+
+		fixed-link {
+			speed = <1000>;
+			duplex-full;
+		};
+	};
+
+	mdio0: mdio@10000000 {
+		compatible = "brcm,unimac-mdio";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		switch0: ethernet-switch@30 {
+			compatible = "brcm,bcm53125";
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			ports {
+				port0@0 {
+					reg = <0>;
+					label = "lan1";
+				};
+
+				port1@1 {
+					reg = <1>;
+					label = "lan2";
+				};
+
+				port5@5 {
+					reg = <5>;
+					label = "cable-modem";
+					fixed-link {
+						speed = <1000>;
+						duplex-full;
+					};
+					phy-mode = "rgmii-txid";
+				};
+
+				port8@8 {
+					reg = <8>;
+					label = "cpu";
+					fixed-link {
+						speed = <1000>;
+						duplex-full;
+					};
+					phy-mode = "rgmii-txid";
+					ethernet = <&eth0>;
+				};
+			};
+		};
+	};