iio: core: Introduce ENERGY channel type

Human activity sensors report the energy burnt by the user.
One of this devices is Freescale's MMA9553L
(http://www.freescale.com/files/sensors/doc/ref_manual/MMA9553LSWRM.pdf)
that computes the number of calories based on weight and step rate.

Introduce a new channel type ENERGY to export these values.

Signed-off-by: Irina Tirdea <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 831db86..3311886 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -282,6 +282,7 @@
 What:		/sys/bus/iio/devices/iio:deviceX/in_accel_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_accel_peak_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_anglvel_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_energy_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_magn_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_magn_x_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_magn_y_scale
@@ -1049,6 +1050,15 @@
 		For a list of available output power modes read
 		in_accel_power_mode_available.
 
+What:		/sys/.../iio:deviceX/in_energy_input
+What:		/sys/.../iio:deviceX/in_energy_raw
+KernelVersion:	3.20
+Contact:	[email protected]
+Description:
+		This attribute is used to read the energy value reported by the
+		device (e.g.: human activity sensors report energy burnt by the
+		user). Units after application of scale are Joules.
+
 What:		/sys/bus/iio/devices/iio:deviceX/store_eeprom
 KernelVersion:	3.4.0
 Contact:	[email protected]