iio: adc: Add Texas Instruments ADC081C021/027 support

Add support for reading conversion results from the ADC and provide them
through a single IIO channel. A proper scaling factor is also exported
based on the reference voltage provided by a regulator.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 408557b..961b8d0 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -115,4 +115,14 @@
 	  max11646, max11647) Provides direct access via sysfs and buffered
 	  data via the iio dev interface.
 
+config TI_ADC081C
+	tristate "Texas Instruments ADC081C021/027"
+	depends on I2C
+	help
+	  If you say yes here you get support for Texas Instruments ADC081C021
+	  and ADC081C027 ADC chips.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ti-adc081c.
+
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