i2c: hix5hd2: add i2c controller driver

I2C drivers for hix5hd2 soc series, including following chipset
Hi3716CV200, Hi3719CV100, Hi3718CV100, Hi3719MV100, Hi3718MV100.
Signed-off-by: Wei Yan <sledge.yanwei@huawei.com>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
[wsa: folded dt docs into this patch]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-hix5hd2.txt

+I2C for Hisilicon hix5hd2 chipset platform
+
+Required properties:
+- compatible: Must be "hisilicon,hix5hd2-i2c"
+- reg: physical base address of the controller and length of memory mapped
+     region.
+- interrupts: interrupt number to the cpu.
+- #address-cells = <1>;
+- #size-cells = <0>;
+- clocks: phandles to input clocks.
+
+Optional properties:
+- clock-frequency: Desired I2C bus frequency in Hz, otherwise defaults to 100000
+- Child nodes conforming to i2c bus binding
+
+Examples:
+I2C0@f8b10000 {
+	compatible = "hisilicon,hix5hd2-i2c";
+	reg = <0xf8b10000 0x1000>;
+	interrupts = <0 38 4>;
+	clocks = <&clock HIX5HD2_I2C0_RST>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+}

drivers/i2c/busses/Kconfig

@@ -77,6 +77,16 @@ config I2C_AMD8111
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-amd8111.
 
+config I2C_HIX5HD2
+	tristate "Hix5hd2 high-speed I2C driver"
+	depends on ARCH_HIX5HD2
+	help
+	  Say Y here to include support for high-speed I2C controller in the
+	  Hisilicon based hix5hd2 SoCs.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-hix5hd2.
+
 config I2C_I801
 	tristate "Intel 82801 (ICH/PCH)"
 	depends on PCI

drivers/i2c/busses/Makefile

@@ -48,6 +48,7 @@ obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
 obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
 obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
 obj-$(CONFIG_I2C_HIGHLANDER)	+= i2c-highlander.o
+obj-$(CONFIG_I2C_HIX5HD2)	+= i2c-hix5hd2.o
 obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o