mfd: Add STMPE I/O Expander support

Add support for the STMPE family of I/O Expanders from
STMicroelectronics.  These devices include upto 24 gpios and a varying
selection of blocks, including PWM, keypad, and touchscreen controllers.
This patch adds the MFD core.

[l.fu@pengutronix.de: fix stmpe811 enable hook]
[l.fu@pengutronix.de: add touchscreen platform data]
Acked-by: Luotao Fu <l.fu@pengutronix.de>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 29781ca..8f5145b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -186,6 +186,29 @@
 	select MFD_CORE
 	default n
 
+config MFD_STMPE
+	bool "Support STMicroelectronics STMPE"
+	depends on I2C=y && GENERIC_HARDIRQS
+	select MFD_CORE
+	help
+	  Support for the STMPE family of I/O Expanders from
+	  STMicroelectronics.
+
+	  Currently supported devices are:
+
+		STMPE811: GPIO, Touchscreen
+		STMPE1601: GPIO, Keypad
+		STMPE2401: GPIO, Keypad
+		STMPE2403: GPIO, Keypad
+
+	  This driver provides common support for accessing the device,
+	  additional drivers must be enabled in order to use the functionality
+	  of the device.  Currently available sub drivers are:
+
+		GPIO: stmpe-gpio
+		Keypad: stmpe-keypad
+		Touchscreen: stmpe-ts
+
 config MFD_TC35892
 	bool "Support Toshiba TC35892"
 	depends on I2C=y && GENERIC_HARDIRQS