iio: types: add IIO_VOLUMEFLOW channel type

Add a new IIO channel type for liquid volumetric flow sensors.  The
unit exposed via the standard _scale attribute is cubic metres per
second (m^3/s), following the SI convention used by the other IIO
channel types.

Update iio-core's name table, the iio_event_monitor whitelist and
the sysfs-bus-iio ABI document to match.  The new _scale attribute is
folded into the existing shared _scale block; only the per-type _raw
needs a fresh entry.

Signed-off-by: Wadim Mueller <wafgo01@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

Documentation/ABI/testing/sysfs-bus-iio

@@ -508,6 +508,8 @@ What:		/sys/bus/iio/devices/iio:deviceX/in_intensity_red_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_intensity_green_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_intensity_blue_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_co2_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_volumeflow_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_volumeflowY_scale
 KernelVersion:	2.6.35
 Contact:	linux-iio@vger.kernel.org
 Description:
@@ -2498,3 +2500,12 @@ Description:
 		seconds, expressed as:
 
 		- a range specified as "[min step max]"
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_volumeflow_raw
+What:		/sys/bus/iio/devices/iio:deviceX/in_volumeflowY_raw
+KernelVersion:	7.3
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Raw (unscaled) volumetric flow rate reading from the channel.
+		To convert to standard units (cubic metres per second, m^3/s)
+		apply the channel's _scale (and _offset, when present).

drivers/iio/industrialio-core.c

@@ -99,6 +99,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_ATTENTION] = "attention",
 	[IIO_ALTCURRENT] = "altcurrent",
 	[IIO_COVERAGE] = "coverage",
+	[IIO_VOLUMEFLOW] = "volumeflow",
 };
 
 static const char * const iio_modifier_names[] = {

include/uapi/linux/iio/types.h

@@ -54,6 +54,7 @@ enum iio_chan_type {
 	IIO_ATTENTION,
 	IIO_ALTCURRENT,
 	IIO_COVERAGE,
+	IIO_VOLUMEFLOW,
 };
 
 enum iio_modifier {

tools/iio/iio_event_monitor.c

@@ -66,6 +66,7 @@ static const char * const iio_chan_type_name_spec[] = {
 	[IIO_ATTENTION] = "attention",
 	[IIO_ALTCURRENT] = "altcurrent",
 	[IIO_COVERAGE] = "coverage",
+	[IIO_VOLUMEFLOW] = "volumeflow",
 };
 
 static const char * const iio_ev_type_text[] = {
@@ -196,6 +197,7 @@ static bool event_is_known(struct iio_event_data *event)
 	case IIO_ATTENTION:
 	case IIO_ALTCURRENT:
 	case IIO_COVERAGE:
+	case IIO_VOLUMEFLOW:
 		break;
 	default:
 		return false;