mfd: add AB4500 driver

This adds core driver support for AB4500 mixed signal
multimedia & power management chip. This connects to U8500
on the SSP (pl022) and exports read/write functions for
the device to get access to this chip. This also registers
the client devices and sets the parent.

Signed-off-by: srinidhi kasagar <srinidhi.kasagar@stericsson.com>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Reviewed-by: Mark Brown <broonie@sirena.org.uk>
Reviewed-by: Jean-Christophe <plagnioj@jcrosoft.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 26a36f8..2aea25b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -329,6 +329,16 @@
 	  individual components like voltage regulators, RTC and
 	  battery-charger under the corresponding menus.
 
+config AB4500_CORE
+	tristate "ST-Ericsson's AB4500 Mixed Signal Power management chip"
+	depends on SPI
+	default y
+	help
+	  Select this option to enable access to AB4500 power management
+	  chip. This connects to U8500 on the SSP/SPI bus and exports
+	  read/write functions for the devices to get access to this chip.
+	  This chip embeds various other multimedia funtionalities as well.
+
 endmenu
 
 menu "Multimedia Capabilities Port drivers"