ARM: bL_switcher: add a simple /dev user interface for debugging purposes

Only the basic call to aid debugging.

*** NOT FOR PRODUCTION ***

Usage:

	echo <cpuid>,<clusterid> > /dev/b.L_switcher

where <cpuid> is the logical CPU number, and <clusterid> is 0 for the
first cluster and 1 for the second cluster.

Signed-off-by: nicolas Pitre <nico@linaro.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index ade7001..cfcb0d8 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1556,6 +1556,14 @@
 	  transparently handle transition between a cluster of A15's
 	  and a cluster of A7's in a big.LITTLE system.
 
+config BL_SWITCHER_DUMMY_IF
+	tristate "Simple big.LITTLE switcher user interface"
+	depends on BL_SWITCHER && DEBUG_KERNEL
+	help
+	  This is a simple and dummy char dev interface to control
+	  the big.LITTLE switcher core code.  It is meant for
+	  debugging purposes only.
+
 choice
 	prompt "Memory split"
 	default VMSPLIT_3G