i2c: iproc: Add Broadcom iProc I2C Driver

Add initial support to the Broadcom iProc I2C controller found in the
iProc family of SoCs.

The iProc I2C controller has separate internal TX and RX FIFOs, each has
a size of 64 bytes. The iProc I2C controller supports two bus speeds
including standard mode (100kHz) and fast mode (400kHz)

Signed-off-by: Ray Jui <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
Reviewed-by: Kevin Cernekee <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>

Documentation/devicetree/bindings/i2c/brcm,iproc-i2c.txt

@@ -0,0 +1,37 @@
+Broadcom iProc I2C controller
+
+Required properties:
+
+- compatible:
+    Must be "brcm,iproc-i2c"
+
+- reg:
+    Define the base and range of the I/O address space that contain the iProc
+    I2C controller registers
+
+- interrupts:
+    Should contain the I2C interrupt
+
+- clock-frequency:
+    This is the I2C bus clock. Need to be either 100000 or 400000
+
+- #address-cells:
+    Always 1 (for I2C addresses)
+
+- #size-cells:
+    Always 0
+
+Example:
+	i2c0: i2c@18008000 {
+		compatible = "brcm,iproc-i2c";
+		reg = <0x18008000 0x100>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		interrupts = <GIC_SPI 85 IRQ_TYPE_NONE>;
+		clock-frequency = <100000>;
+
+		codec: wm8750@1a {
+			compatible = "wlf,wm8750";
+			reg = <0x1a>;
+		};
+	};