staging:iio:documentation Add abi docs for capacitance adcs.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Documentation/sysfs-bus-iio

@@ -92,6 +92,24 @@ Description:
 		is required is a consistent labeling.  Units after application
 		of scale and offset are microvolts.
 
+What:		/sys/bus/iio/devices/iio:deviceX/in_capacitanceY_raw
+KernelVersion:	3.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw capacitance measurement from channel Y. Units after
+		application of scale and offset are nanofarads.
+
+What:		/sys/.../iio:deviceX/in_capacitanceY-in_capacitanceZ_raw
+KernelVersion:	3.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw differential capacitance measurement equivalent to
+		channel Y - channel Z where these channel numbers apply to the
+		physically equivalent inputs when non differential readings are
+		separately available. In differential only parts, then all that
+		is required is a consistent labeling.  Units after application
+		of scale and offset are nanofarads..
+
 What:		/sys/bus/iio/devices/iio:deviceX/in_temp_raw
 What:		/sys/bus/iio/devices/iio:deviceX/in_tempX_raw
 What:		/sys/bus/iio/devices/iio:deviceX/in_temp_x_raw
@@ -251,6 +269,7 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_accel_scale_available
 What:		/sys/.../iio:deviceX/in_voltageX_scale_available
 What:		/sys/.../iio:deviceX/in_voltage-voltage_scale_available
 What:		/sys/.../iio:deviceX/out_voltageX_scale_available
+What:		/sys/.../iio:deviceX/in_capacitance_scale_available
 KernelVersion:	2.635
 Contact:	linux-iio@vger.kernel.org
 Description: