i2c: rk3x: add driver for Rockchip RK3xxx SoC I2C adapter

Driver for the native I2C adapter found in Rockchip RK3xxx SoCs.

Configuration is only possible through devicetree. The driver is
interrupt driven and supports the I2C_M_IGNORE_NAK mangling bit.
Signed-off-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-rk3x.txt

+* 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>;
+};

drivers/i2c/busses/Kconfig

@@ -676,6 +676,16 @@ config I2C_RIIC
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-riic.
 
+config I2C_RK3X
+	tristate "Rockchip RK3xxx I2C adapter"
+	depends on OF
+	help
+	  Say Y here to include support for the I2C adapter in Rockchip RK3xxx
+	  SoCs.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called i2c-rk3x.
+
 config HAVE_S3C2410_I2C
 	bool
 	help

drivers/i2c/busses/Makefile

@@ -66,6 +66,7 @@ obj-$(CONFIG_I2C_PXA)		+= i2c-pxa.o
 obj-$(CONFIG_I2C_PXA_PCI)	+= i2c-pxa-pci.o
 obj-$(CONFIG_I2C_QUP)		+= i2c-qup.o
 obj-$(CONFIG_I2C_RIIC)		+= i2c-riic.o
+obj-$(CONFIG_I2C_RK3X)		+= i2c-rk3x.o
 obj-$(CONFIG_I2C_S3C2410)	+= i2c-s3c2410.o
 obj-$(CONFIG_I2C_S6000)		+= i2c-s6000.o
 obj-$(CONFIG_I2C_SH7760)	+= i2c-sh7760.o