iio: Add pressure channel type

This patch adds support for a new IIO channel type for pressure measurements.
This can for example be used for barometric pressure sensors.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/ABI/testing/sysfs-bus-iio

@@ -189,6 +189,14 @@ Description:
 		A computed peak value based on the sum squared magnitude of
 		the underlying value in the specified directions.
 
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_raw
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_raw
+KernelVersion:	3.8
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw pressure measurement from channel Y. Units after
+		application of scale and offset are kilopascal.
+
 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
@@ -197,6 +205,8 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_offset
 What:		/sys/bus/iio/devices/iio:deviceX/in_voltage_offset
 What:		/sys/bus/iio/devices/iio:deviceX/in_tempY_offset
 What:		/sys/bus/iio/devices/iio:deviceX/in_temp_offset
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_offset
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_offset
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -226,6 +236,8 @@ 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
 What:		/sys/bus/iio/devices/iio:deviceX/in_magn_z_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_scale
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -245,6 +257,8 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_anglvel_y_calibbias
 What:		/sys/bus/iio/devices/iio:deviceX/in_anglvel_z_calibbias
 What:		/sys/bus/iio/devices/iio:deviceX/in_illuminance0_calibbias
 What:		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calibbias
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_calibbias
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_calibbias
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -262,6 +276,8 @@ What		/sys/bus/iio/devices/iio:deviceX/in_anglvel_y_calibscale
 What		/sys/bus/iio/devices/iio:deviceX/in_anglvel_z_calibscale
 what		/sys/bus/iio/devices/iio:deviceX/in_illuminance0_calibscale
 what		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calibscale
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_calibscale
+What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_calibscale
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -275,6 +291,8 @@ What:		/sys/.../iio:deviceX/in_voltage-voltage_scale_available
 What:		/sys/.../iio:deviceX/out_voltageX_scale_available
 What:		/sys/.../iio:deviceX/out_altvoltageX_scale_available
 What:		/sys/.../iio:deviceX/in_capacitance_scale_available
+What:		/sys/.../iio:deviceX/in_pressure_scale_available
+What:		/sys/.../iio:deviceX/in_pressureY_scale_available
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -694,6 +712,8 @@ What:		/sys/.../buffer/scan_elements/in_voltageY_en
 What:		/sys/.../buffer/scan_elements/in_voltageY-voltageZ_en
 What:		/sys/.../buffer/scan_elements/in_incli_x_en
 What:		/sys/.../buffer/scan_elements/in_incli_y_en
+What:		/sys/.../buffer/scan_elements/in_pressureY_en
+What:		/sys/.../buffer/scan_elements/in_pressure_en
 KernelVersion:	2.6.37
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -707,6 +727,8 @@ What:		/sys/.../buffer/scan_elements/in_voltageY_type
 What:		/sys/.../buffer/scan_elements/in_voltage_type
 What:		/sys/.../buffer/scan_elements/in_voltageY_supply_type
 What:		/sys/.../buffer/scan_elements/in_timestamp_type
+What:		/sys/.../buffer/scan_elements/in_pressureY_type
+What:		/sys/.../buffer/scan_elements/in_pressure_type
 KernelVersion:	2.6.37
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -751,6 +773,8 @@ What:		/sys/.../buffer/scan_elements/in_magn_z_index
 What:		/sys/.../buffer/scan_elements/in_incli_x_index
 What:		/sys/.../buffer/scan_elements/in_incli_y_index
 What:		/sys/.../buffer/scan_elements/in_timestamp_index
+What:		/sys/.../buffer/scan_elements/in_pressureY_index
+What:		/sys/.../buffer/scan_elements/in_pressure_index
 KernelVersion:	2.6.37
 Contact:	linux-iio@vger.kernel.org
 Description:

drivers/iio/industrialio-core.c

@@ -65,6 +65,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_CAPACITANCE] = "capacitance",
 	[IIO_ALTVOLTAGE] = "altvoltage",
 	[IIO_CCT] = "cct",
+	[IIO_PRESSURE] = "pressure",
 };
 
 static const char * const iio_modifier_names[] = {

include/linux/iio/types.h

@@ -28,6 +28,7 @@ enum iio_chan_type {
 	IIO_CAPACITANCE,
 	IIO_ALTVOLTAGE,
 	IIO_CCT,
+	IIO_PRESSURE,
 };
 
 enum iio_modifier {