mfd: Add WM831x SPI support

Implement support for controlling WM831x and WM832x devices using SPI.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 2fb1e89..3a1493b 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -329,6 +329,17 @@
 	  for accessing the device, additional drivers must be enabled in
 	  order to use the functionality of the device.
 
+config MFD_WM831X_SPI
+	bool "Support Wolfson Microelectronics WM831x/2x PMICs with SPI"
+	select MFD_CORE
+	select MFD_WM831X
+	depends on SPI_MASTER && GENERIC_HARDIRQS
+	help
+	  Support for the Wolfson Microelecronics WM831x and WM832x PMICs
+	  when controlled using SPI.  This driver provides common support
+	  for accessing the device, additional drivers must be enabled in
+	  order to use the functionality of the device.
+
 config MFD_WM8350
 	bool
 	depends on GENERIC_HARDIRQS