iio: add configuration option for debug support

Signed-off-by: NOtavio Salvador <otavio@ossystems.com.br>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/Kconfig

@@ -12,6 +12,13 @@ menuconfig IIO
 
 if IIO
 
+config IIO_DEBUG
+	boolean "Debug support for Industrial I/O"
+	depends on DEBUG_KERNEL
+	help
+	  Say "yes" to enable debug messaging (like dev_dbg and pr_debug)
+	  support in Industrial I/O subsystem and drivers.
+
 config IIO_BUFFER
 	bool "Enable buffer support within IIO"
 	help

drivers/iio/Makefile

@@ -2,6 +2,8 @@
 # Makefile for the industrial I/O core.
 #
 
+ccflags-$(CONFIG_IIO_DEBUG) := -DDEBUG
+
 obj-$(CONFIG_IIO) += industrialio.o
 industrialio-y := industrialio-core.o industrialio-event.o inkern.o
 industrialio-$(CONFIG_IIO_BUFFER) += industrialio-buffer.o