mfd: AB3550 core driver

This adds a core driver for the AB3550 mixed-signal circuit
found in the ST-Ericsson U300 platforms. This driver
is a singleton proxy for all access to the AB3550 sub
functionality drivers which can be added on top of this one:
RTC, regulators, battery and system power control, vibrator,
LEDs and an ALSA codec.
Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/Kconfig

@@ -423,6 +423,20 @@ config AB4500_CORE
 	  read/write functions for the devices to get access to this chip.
 	  This chip embeds various other multimedia funtionalities as well.
 
+config AB3550_CORE
+        bool "ST-Ericsson AB3550 Mixed Signal Circuit core functions"
+	select MFD_CORE
+	depends on I2C=y && GENERIC_HARDIRQS && ABX500_CORE
+	help
+	  Select this to enable the AB3550 Mixed Signal IC core
+	  functionality. This connects to a AB3550 on the I2C bus
+	  and expose a number of symbols needed for dependent devices
+	  to read and write registers and subscribe to events from
+	  this multi-functional IC. This is needed to use other features
+	  of the AB3550 such as battery-backed RTC, charging control,
+	  LEDs, vibrator, system power and temperature, power management
+	  and ALSA sound.
+
 config MFD_TIMBERDALE
 	tristate "Support for the Timberdale FPGA"
 	select MFD_CORE

drivers/mfd/Makefile

@@ -64,6 +64,7 @@ obj-$(CONFIG_ABX500_CORE)	+= abx500-core.o
 obj-$(CONFIG_AB3100_CORE)	+= ab3100-core.o
 obj-$(CONFIG_AB3100_OTP)	+= ab3100-otp.o
 obj-$(CONFIG_AB4500_CORE)	+= ab4500-core.o
+obj-$(CONFIG_AB3550_CORE)	+= ab3550-core.o
 obj-$(CONFIG_MFD_TIMBERDALE)    += timberdale.o
 obj-$(CONFIG_PMIC_ADP5520)	+= adp5520.o
 obj-$(CONFIG_LPC_SCH)		+= lpc_sch.o