mfd: Add JZ4740 ADC driver

This patch adds a MFD driver for the JZ4740 ADC unit. The driver is used to
demultiplex IRQs and synchronize access to shared registers between the
battery, hwmon and (future) touchscreen driver.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 8f5145b..d59334f 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -514,6 +514,14 @@
 	  host many different types of MODULbus daughterboards, including
 	  CAN and GPIO controllers.
 
+config MFD_JZ4740_ADC
+	tristate "Support for the JZ4740 SoC ADC core"
+	select MFD_CORE
+	depends on MACH_JZ4740
+	help
+	  Say yes here if you want support for the ADC unit in the JZ4740 SoC.
+	  This driver is necessary for jz4740-battery and jz4740-hwmon driver.
+
 endif # MFD_SUPPORT
 
 menu "Multimedia Capabilities Port drivers"