i2c: add support for Amlogic Meson I2C controller

This is a driver for the I2C controller found in Amlogic Meson SoCs.
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

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

+Amlogic Meson I2C controller
+
+Required properties:
+ - compatible: must be "amlogic,meson6-i2c"
+ - reg: physical address and length of the device registers
+ - interrupts: a single interrupt specifier
+ - clocks: clock for the device
+ - #address-cells: should be <1>
+ - #size-cells: should be <0>
+
+Optional properties:
+- clock-frequency: the desired I2C bus clock frequency in Hz; in
+  absence of this property the default value is used (100 kHz).
+
+Examples:
+
+	i2c@c8100500 {
+		compatible = "amlogic,meson6-i2c";
+		reg = <0xc8100500 0x20>;
+		interrupts = <0 92 1>;
+		clocks = <&clk81>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};

drivers/i2c/busses/Kconfig

@@ -564,6 +564,13 @@ config I2C_KEMPLD
 	  This driver can also be built as a module. If so, the module
 	  will be called i2c-kempld.
 
+config I2C_MESON
+	tristate "Amlogic Meson I2C controller"
+	depends on ARCH_MESON
+	help
+	  If you say yes to this option, support will be included for the
+	  I2C interface on the Amlogic Meson family of SoCs.
+
 config I2C_MPC
 	tristate "MPC107/824x/85xx/512x/52xx/83xx/86xx"
 	depends on PPC

drivers/i2c/busses/Makefile

@@ -54,6 +54,7 @@ obj-$(CONFIG_I2C_IMG)		+= i2c-img-scb.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
+obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
 obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
 obj-$(CONFIG_I2C_MXS)		+= i2c-mxs.o