mfd: si476x: Add header files and Kbuild plumbing

This patch adds all necessary header files and Kbuild plumbing for the
core driver for Silicon Laboratories Si476x series of AM/FM tuner
chips.

The driver as a whole is implemented as an MFD device and this patch
adds a core portion of it that provides all the necessary
functionality to the two other drivers that represent radio and audio
codec subsystems of the chip.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/Kconfig

@@ -487,6 +487,19 @@ config MFD_SEC_CORE
 	 additional drivers must be enabled in order to use the functionality
 	 of the device
 
+config MFD_SI476X_CORE
+	tristate "Silicon Laboratories 4761/64/68 AM/FM radio."
+	depends on I2C
+	select MFD_CORE
+	select REGMAP_I2C
+	help
+	  This is the core driver for the SI476x series of AM/FM
+	  radio. This MFD driver connects the radio-si476x V4L2 module
+	  and the si476x audio codec.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called si476x-core.
+
 config MFD_SM501
 	tristate "Silicon Motion SM501"
 	 ---help---

drivers/mfd/Makefile

@@ -134,6 +134,10 @@ obj-$(CONFIG_MFD_JZ4740_ADC)	+= jz4740-adc.o
 obj-$(CONFIG_MFD_TPS6586X)	+= tps6586x.o
 obj-$(CONFIG_MFD_VX855)		+= vx855.o
 obj-$(CONFIG_MFD_WL1273_CORE)	+= wl1273-core.o
+
+si476x-core-y := si476x-cmd.o si476x-prop.o si476x-i2c.o
+obj-$(CONFIG_MFD_SI476X_CORE)	+= si476x-core.o
+
 obj-$(CONFIG_MFD_CS5535)	+= cs5535-mfd.o
 obj-$(CONFIG_MFD_OMAP_USB_HOST)	+= omap-usb-host.o omap-usb-tll.o
 obj-$(CONFIG_MFD_PM8921_CORE) 	+= pm8921-core.o