ARM: dts: Add i2c-arbitrator bus for exynos5250-snow

We need to use the i2c-arbitrator to talk to any of the devices on i2c
bus 4 on exynos5250-snow so that we don't confuse the embedded
controller (EC).  Add the i2c-arbitrator to the device tree.  As we
add future devices (keyboard, sbs, tps65090) we'll add them on top of
this.

The arbitrated bus is numbered 104 simply as a convenience to make it
easier for people poking around to guess that it might have something
to do with the physical bus 4.

The addition is split between the cros5250-common and the snow device
tree file since not all cros5250-class devices use arbitration.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/boot/dts/cros5250-common.dtsi

@@ -193,7 +193,8 @@ i2c@12C90000 {
 	};
 
 	i2c@12CA0000 {
-		status = "disabled";
+		samsung,i2c-sda-delay = <100>;
+		samsung,i2c-max-bus-freq = <66000>;
 	};
 
 	i2c@12CB0000 {

arch/arm/boot/dts/exynos5250-snow.dts

@@ -16,6 +16,10 @@ / {
 	model = "Google Snow";
 	compatible = "google,snow", "samsung,exynos5250";
 
+	aliases {
+		i2c104 = &i2c_104;
+	};
+
 	pinctrl@11400000 {
 		sd3_clk: sd3-clk {
 			samsung,pin-drv = <0>;
@@ -44,6 +48,27 @@ lid-switch {
 		};
 	};
 
+	i2c-arbitrator {
+		compatible = "i2c-arb-gpio-challenge";
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		i2c-parent = <&{/i2c@12CA0000}>;
+
+		our-claim-gpio = <&gpf0 3 1>;
+		their-claim-gpios = <&gpe0 4 1>;
+		slew-delay-us = <10>;
+		wait-retry-us = <3000>;
+		wait-free-us = <50000>;
+
+		/* Use ID 104 as a hint that we're on physical bus 4 */
+		i2c_104: i2c@0 {
+			reg = <0>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+		};
+	};
+
 	/*
 	 * On Snow we've got SIP WiFi and so can keep drive strengths low to
 	 * reduce EMI.