* Rockchip RK3xxx I2C controller

This driver interfaces with the native I2C controller present in Rockchip
RK3xxx SoCs.

Required properties :

 - reg : Offset and length of the register set for the device
 - compatible : should be "rockchip,rk3066-i2c", "rockchip,rk3188-i2c" or
		"rockchip,rk3288-i2c".
 - interrupts : interrupt number
 - clocks : parent clock

Required on RK3066, RK3188 :

 - rockchip,grf : the phandle of the syscon node for the general register
		  file (GRF)
 - on those SoCs an alias with the correct I2C bus ID (bit offset in the GRF)
   is also required.

Optional properties :

 - clock-frequency : SCL frequency to use (in Hz). If omitted, 100kHz is used.

Example:

aliases {
	i2c0 = &i2c0;
}

i2c0: i2c@2002d000 {
	compatible = "rockchip,rk3188-i2c";
	reg = <0x2002d000 0x1000>;
	interrupts = <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>;
	#address-cells = <1>;
	#size-cells = <0>;

	rockchip,grf = <&grf>;

	clock-names = "i2c";
	clocks = <&cru PCLK_I2C0>;
};