iio: adc: add exynos adc driver under iio framwork

This patch adds New driver to support:
1. Supports ADC IF found on EXYNOS4412/EXYNOS5250
   and future SoCs from Samsung
2. Add ADC driver under iio/adc framework
3. Also adds the Documentation for device tree bindings
Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt

+Samsung Exynos Analog to Digital Converter bindings
+
+This devicetree binding are for the new adc driver written fori
+Exynos4 and upward SoCs from Samsung.
+
+New driver handles the following
+1. Supports ADC IF found on EXYNOS4412/EXYNOS5250
+   and future SoCs from Samsung
+2. Add ADC driver under iio/adc framework
+3. Also adds the Documentation for device tree bindings
+
+Required properties:
+- compatible:		Must be "samsung,exynos-adc-v1"
+				for exynos4412/5250 controllers.
+			Must be "samsung,exynos-adc-v2" for
+				future controllers.
+- reg:			Contains ADC register address range (base address and
+			length).
+- interrupts: 		Contains the interrupt information for the timer. The
+			format is being dependent on which interrupt controller
+			the Samsung device uses.
+- #io-channel-cells = <1>; As ADC has multiple outputs
+
+Note: child nodes can be added for auto probing from device tree.
+
+Example: adding device info in dtsi file
+
+adc: adc@12D10000 {
+	compatible = "samsung,exynos-adc-v1";
+	reg = <0x12D10000 0x100>;
+	interrupts = <0 106 0>;
+	#io-channel-cells = <1>;
+	io-channel-ranges;
+};
+
+
+Example: Adding child nodes in dts file
+
+adc@12D10000 {
+
+	/* NTC thermistor is a hwmon device */
+	ncp15wb473@0 {
+		compatible = "ntc,ncp15wb473";
+		pullup-uV = <1800000>;
+		pullup-ohm = <47000>;
+		pulldown-ohm = <0>;
+		io-channels = <&adc 4>;
+	};
+};
+
+Note: Does not apply to ADC driver under arch/arm/plat-samsung/
+Note: The child node can be added under the adc node or seperately.

drivers/iio/adc/Kconfig

@@ -103,6 +103,13 @@ config AT91_ADC
 	help
 	  Say yes here to build support for Atmel AT91 ADC.
 
+config EXYNOS_ADC
+	bool "Exynos ADC driver support"
+	help
+	  Core support for the ADC block found in the Samsung EXYNOS series
+	  of SoCs for drivers such as the touchscreen and hwmon to use to share
+	  this resource.
+
 config LP8788_ADC
 	bool "LP8788 ADC driver"
 	depends on MFD_LP8788

drivers/iio/adc/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_AD7791) += ad7791.o
 obj-$(CONFIG_AD7793) += ad7793.o
 obj-$(CONFIG_AD7887) += ad7887.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
+obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
 obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o