i2c: efm32: new bus driver

This was tested on a EFM32GG-DK3750 devboard that has a temperature
sensor and an eeprom on its i2c bus.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-efm32.txt

+* Energymicro efm32 i2c controller
+
+Required properties :
+
+ - reg : Offset and length of the register set for the device
+ - compatible : should be "efm32,i2c"
+ - interrupts : the interrupt number
+ - clocks : reference to the module clock
+
+Recommended properties :
+
+ - clock-frequency : maximal I2C bus clock frequency in Hz.
+ - efm32,location : Decides the location of the USART I/O pins.
+   Allowed range : [0 .. 6]
+
+Example:
+	i2c0: i2c@4000a000 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "efm32,i2c";
+		reg = <0x4000a000 0x400>;
+		interrupts = <9>;
+		clocks = <&cmu clk_HFPERCLKI2C0>;
+		clock-frequency = <100000>;
+		status = "disabled";
+		efm32,location = <3>;
+
+		eeprom@50 {
+			compatible = "microchip,24c02";
+			reg = <0x50>;
+			pagesize = <16>;
+		};
+	};
+

drivers/i2c/busses/Kconfig

@@ -433,6 +433,13 @@ config I2C_DESIGNWARE_PCI
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-designware-pci.
 
+config I2C_EFM32
+	tristate "EFM32 I2C controller"
+	depends on ARCH_EFM32 || COMPILE_TEST
+	help
+	  This driver supports the i2c block found in Energy Micro's EFM32
+	  SoCs.
+
 config I2C_EG20T
 	tristate "Intel EG20T PCH/LAPIS Semicon IOH(ML7213/ML7223/ML7831) I2C"
 	depends on PCI

drivers/i2c/busses/Makefile

@@ -41,6 +41,7 @@ obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM)	+= i2c-designware-platform.o
 i2c-designware-platform-objs := i2c-designware-platdrv.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+= i2c-designware-pci.o
 i2c-designware-pci-objs := i2c-designware-pcidrv.o
+obj-$(CONFIG_I2C_EFM32)		+= i2c-efm32.o
 obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
 obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
 obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o