regulator: Add stub regulator support

Add support for a dummy driver that has an implementation
connected to no real hardware devices. Its purpose is to aid
bringup scenarios by providing clients a regulator interface
that they expect. This driver shouldn't be enabled if a real
device implementation for a particular platform already exists.

Change-Id: Ib83027b4e599ebbc3cb153b2f346bb03495bb746
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 49e0d0e..fb1a99f 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -344,5 +344,14 @@
 	  chip. It is only supposed to be used when Linux on application
 	  processor is the master in control of XO buffers.
 
+config REGULATOR_STUB
+	tristate "Stub Regulator"
+	help
+	  This driver adds stub regulator support. The driver is absent of any
+	  real hardware based implementation. It allows for clients to register
+	  their regulator device constraints and use all of the standard
+	  regulator interfaces. This is useful for bringing up new platforms
+	  when the real hardware based implementation may not be yet available.
+	  Clients can use the real regulator device names with proper
+	  constraint checking while the real driver is being developed.
 endif
-