Re: [RFC PATCH v1 1/4] iio: types: add IIO_VOLUMEFLOW channel type

[Guenter Roeck]

On 5/24/26 13:49, Wadim Mueller wrote:
> From: Wadim Mueller <wadim.mueller@xxxxxxxx>
>
> Add a new IIO channel type for liquid volumetric flow sensors.  The
> unit exposed via the standard _scale attribute is litres per second
> (l/s), so drivers reporting smaller native units (e.g. ml/min) only
> need to set a fractional scale.

Two questions: Why restricting to liquid (there are also gas flow sensors),
and why litres/second and not per minute which seems to be a more common
unit ?

More on the latter in patch 3.

Thanks,
Guenter

> Update iio-core's name table, the iio_event_monitor whitelist and
> the sysfs-bus-iio ABI document to match.
>
> Signed-off-by: Wadim Mueller <wadim.mueller@xxxxxxxx>
> ---
>   Documentation/ABI/testing/sysfs-bus-iio | 17 +++++++++++++++++
>   drivers/iio/industrialio-core.c         |  1 +
>   include/uapi/linux/iio/types.h          |  1 +
>   tools/iio/iio_event_monitor.c           |  2 ++
>   4 files changed, 21 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index 5f87dcee7..68eb703c1 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -2458,3 +2458,20 @@ 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:6.19
> +Contact:linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +Raw (unscaled) volumetric flow rate reading from the channel.
> +To convert to standard units (litres / second) apply the
> +channel's _scale (and _offset, when present).
> +
> +What:/sys/bus/iio/devices/iio:deviceX/in_volumeflow_scale
> +What:/sys/bus/iio/devices/iio:deviceX/in_volumeflowY_scale
> +KernelVersion:6.19
> +Contact:linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +Scale factor applied to raw volumetric flow readings to obtain
> +the value in litres per second (l/s).
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 22eefd048..aa34fcd8e 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -98,6 +98,7 @@ static const char * const iio_chan_type_name_spec[] = {
>   	[IIO_CHROMATICITY] = "chromaticity",
>   	[IIO_ATTENTION] = "attention",
>   	[IIO_ALTCURRENT] = "altcurrent",
> +	[IIO_VOLUMEFLOW] = "volumeflow",
>   };
>   
>   static const char * const iio_modifier_names[] = {
> diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
> index 6d269b844..49480f321 100644
> --- a/include/uapi/linux/iio/types.h
> +++ b/include/uapi/linux/iio/types.h
> @@ -53,6 +53,7 @@ enum iio_chan_type {
>   	IIO_CHROMATICITY,
>   	IIO_ATTENTION,
>   	IIO_ALTCURRENT,
> +	IIO_VOLUMEFLOW,
>   };
>   
>   enum iio_modifier {
> diff --git a/tools/iio/iio_event_monitor.c b/tools/iio/iio_event_monitor.c
> index 03ca33869..078004750 100644
> --- a/tools/iio/iio_event_monitor.c
> +++ b/tools/iio/iio_event_monitor.c
> @@ -65,6 +65,7 @@ static const char * const iio_chan_type_name_spec[] = {
>   	[IIO_CHROMATICITY] = "chromaticity",
>   	[IIO_ATTENTION] = "attention",
>   	[IIO_ALTCURRENT] = "altcurrent",
> +	[IIO_VOLUMEFLOW] = "volumeflow",
>   };
>   
>   static const char * const iio_ev_type_text[] = {
> @@ -193,6 +194,7 @@ static bool event_is_known(struct iio_event_data *event)
>   	case IIO_CHROMATICITY:
>   	case IIO_ATTENTION:
>   	case IIO_ALTCURRENT:
> +	case IIO_VOLUMEFLOW:
>   		break;
>   	default:
>   		return false;