iio: Add support for humidity sensors

There are already humidity sensors in the hwmon subsystem,
so we use their unit (milli percent) here as well.

Signed-off-by: Harald Geyer <harald@ccbib.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index b20e829d..6e02c50 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -197,6 +197,19 @@
 		Raw pressure measurement from channel Y. Units after
 		application of scale and offset are kilopascal.
 
+What:		/sys/bus/iio/devices/iio:deviceX/in_humidityrelative_raw
+KernelVersion:	3.14
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw humidity measurement of air. Units after application of
+		scale and offset are milli percent.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_humidityrelative_input
+KernelVersion:	3.14
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Scaled humidity measurement in milli percent.
+
 What:		/sys/bus/iio/devices/iio:deviceX/in_accel_offset
 What:		/sys/bus/iio/devices/iio:deviceX/in_accel_x_offset
 What:		/sys/bus/iio/devices/iio:deviceX/in_accel_y_offset