mfd: Add driver for RAVE Supervisory Processor

Add a driver for RAVE Supervisory Processor, an MCU implementing
various bits of housekeeping functionality (watchdoging, backlight
control, LED control, etc) on RAVE family of products by Zodiac
Inflight Innovations.

This driver implementes core MFD/serdev device as well as
communication subroutines necessary for commanding the device.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -1859,5 +1859,13 @@ config MFD_VEXPRESS_SYSREG
 	  System Registers are the platform configuration block
 	  on the ARM Ltd. Versatile Express board.
 
+config RAVE_SP_CORE
+	tristate "RAVE SP MCU core driver"
+	depends on SERIAL_DEV_BUS
+	select CRC_CCITT
+	help
+	  Select this to get support for the Supervisory Processor
+	  device found on several devices in RAVE line of hardware.
+
 endmenu
 endif

drivers/mfd/Makefile

@@ -230,3 +230,5 @@ obj-$(CONFIG_MFD_STM32_LPTIMER)	+= stm32-lptimer.o
 obj-$(CONFIG_MFD_STM32_TIMERS) 	+= stm32-timers.o
 obj-$(CONFIG_MFD_MXS_LRADC)     += mxs-lradc.o
 obj-$(CONFIG_MFD_SC27XX_PMIC)	+= sprd-sc27xx-spi.o
+obj-$(CONFIG_RAVE_SP_CORE)	+= rave-sp.o
+