iio: Add IIO support for the DAC on the Apex Embedded Systems STX104

The Apex Embedded Systems STX104 is a 16-channel 16-bit analog input and
2-channel 16-bit analog output PC/104 card. The STX104 incorporates a
large one mega-sample FIFO.

This driver provides IIO support for the 2-channel DAC on the STX104.
The base port addresses for the devices may be configured via the "base"
module parameter array.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 3c809e2..31a1985 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -208,4 +208,13 @@
 	  To compile this driver as a module, choose M here: the module
 	  will be called mcp4922.
 
+config STX104
+	tristate "Apex Embedded Systems STX104 DAC driver"
+	depends on ISA
+	help
+	  Say yes here to build support for the 2-channel DAC on the Apex
+	  Embedded Systems STX104 integrated analog PC/104 card. The base port
+	  addresses for the devices may be configured via the "base" module
+	  parameter array.
+
 endmenu