[PATCH v4 0/3] Re-add filter_type/filter_mode

[PATCH v4 0/3] Re-add filter_type/filter_mode

[Marcelo Schmitt]

Better document sysfs ABI for ADC digital filter configuration.
Also update ad4130 driver to support the standardized IIO ABI for digital filter
configuration.

Change log v3 -> v4
- Renamed in_voltage-voltage_filter_mode_available to
  in_voltage-voltage_filter_type_available instead of just removing the mode
  variant from sysfs-bus-iio.
- Added comment about backwards compatibility near ad4130 filter attribute
  declarations.
- Reordered patches so attributes are documented before use.
- Minor re-word of in_voltage-voltage_filter_mode_available text in
  sysfs-bus-iio-adc-ad4130 to make it more generic.
- Picked up review tags.

Change log v2 -> v3
- Added in_voltageY-voltageZ_filter_type to main IIO ADI doc too.
- Added filter_type attributes to ad4130 driver so it also supports the
  standardized ABI for digital filter configuration.
- No longer dropping AD4130 specific filter_type_available options from sysfs-bus-iio.
- Re-add sysfs-bus-iio-adc-ad4130 just mentioning the ABI at sysfs-bus-iio instead
  of repeating the doc.

Change log v1 -> v2
- Split into 3 patches.
- Re-added sysfs-bus-iio-adc-ad4130 to keep filter_mode separate from filter_type.
- Removed in_voltage-voltage_filter_mode_available from sysfs-bus-iio.
- Added deprecation notes in sysfs-bus-iio-adc-ad4130 asking to use filter_type
  for new drivers and referencing sysfs-bus-iio.
- Improved commit message with explanation about use of filter type attributes.
- Dropped AD4130 specific filter_type_available options from sysfs-bus-iio.

Link to v1: https://lore.kernel.org/linux-iio/b2132bd3ca1d64cdd8d5afab1f1f33c574718b50.1732901318.git.marcelo.schmitt@analog.com/
Link to v2: https://lore.kernel.org/linux-iio/cover.1736261047.git.marcelo.schmitt@analog.com/
Link to v3: https://lore.kernel.org/linux-iio/cover.1738608986.git.marcelo.schmitt@analog.com/


Marcelo Schmitt (3):
  Documentation: ABI: IIO: Add filter_type documentation
  Documentation: ABI: IIO: Re-add sysfs-bus-iio-adc-ad4130
  iio: adc: ad4130: Add filter_type attributes

 Documentation/ABI/testing/sysfs-bus-iio       | 10 +++++++++-
 .../ABI/testing/sysfs-bus-iio-adc-ad4130      | 20 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 drivers/iio/adc/ad4130.c                      |  7 +++++++
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130


base-commit: 9b75dd1b7d6b98699a104c6b1eec0c8817e5fd4b
-- 
2.47.2

[PATCH v4 1/3] Documentation: ABI: IIO: Add filter_type documentation

[Marcelo Schmitt]

A previous patch added documentation for filter_type_available attributes.
However, the description for the value attribute (filter_type) was missing.
Add documentation for filter_type sysfs ABI.

Fixes: 01bb12922b60 ("Documentation: ABI: added filter mode doc in sysfs-bus-iio")
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
---
 Documentation/ABI/testing/sysfs-bus-iio | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index d97c35057a03..ff9cc09360dc 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2300,6 +2300,14 @@ Description:
 		* "sinc3+pf3" - Sinc3 + device specific Post Filter 3.
 		* "sinc3+pf4" - Sinc3 + device specific Post Filter 4.
 
+What:		/sys/bus/iio/devices/iio:deviceX/filter_type
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY-voltageZ_filter_type
+KernelVersion:	6.1
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Specifies which filter type apply to the channel. The possible
+		values are given by the filter_type_available attribute.
+
 What:		/sys/.../events/in_proximity_thresh_either_runningperiod
 KernelVersion:	6.6
 Contact:	linux-iio@vger.kernel.org
-- 
2.47.2

[PATCH v4 2/3] Documentation: ABI: IIO: Re-add sysfs-bus-iio-adc-ad4130

[Marcelo Schmitt]

The ad4130 driver exports in_voltageY-voltageZ_filter_mode and
in_voltage-voltage_filter_mode_available attributes to user space. A
previous patch merged the documentation for those attributes with the
documentation for filter_type/filter_type_available into sysfs-bus-iio.
Filter mode and filter type refer to the same feature which is the digital
filter applied over ADC samples. However, since datasheets use the term
`filter type` and ad4130 driver is the only one using filter_mode,
deprecate the filter_mode ABI in favor of filter_type and keep the docs
separate to avoid confusion and intricate attribute descriptions.

Fixes: 01bb12922b60 ("Documentation: ABI: added filter mode doc in sysfs-bus-iio")
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
---
 Documentation/ABI/testing/sysfs-bus-iio       |  2 +-
 .../ABI/testing/sysfs-bus-iio-adc-ad4130      | 20 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index ff9cc09360dc..2f8898c1a664 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2277,7 +2277,7 @@ Description:
 		representing the sensor unique ID number.
 
 What:		/sys/bus/iio/devices/iio:deviceX/filter_type_available
-What:		/sys/bus/iio/devices/iio:deviceX/in_voltage-voltage_filter_mode_available
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage-voltage_filter_type_available
 KernelVersion:	6.1
 Contact:	linux-iio@vger.kernel.org
 Description:
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130 b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130
new file mode 100644
index 000000000000..d3fad27421d6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130
@@ -0,0 +1,20 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage-voltage_filter_mode_available
+KernelVersion:  6.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Reading returns a list with the possible filter modes.
+
+		This ABI is only kept for backwards compatibility and the values
+		returned are identical to filter_type_available attribute
+		documented in Documentation/ABI/testing/sysfs-bus-iio. Please,
+		use filter_type_available like ABI to provide filter options for
+		new drivers.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY-voltageZ_filter_mode
+KernelVersion:  6.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		This ABI is only kept for backwards compatibility and the values
+		returned are identical to in_voltageY-voltageZ_filter_type
+		attribute documented in Documentation/ABI/testing/sysfs-bus-iio.
+		Please, use in_voltageY-voltageZ_filter_type for new drivers.
diff --git a/MAINTAINERS b/MAINTAINERS
index 98a3c1e46311..28dbbf6d6efa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1279,6 +1279,7 @@ M:	Cosmin Tanislav <cosmin.tanislav@analog.com>
 L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml
 F:	drivers/iio/adc/ad4130.c
 
-- 
2.47.2

[PATCH v4 3/3] iio: adc: ad4130: Add filter_type attributes

[Marcelo Schmitt]

Make filter control also available through filter_type attributes which are
now standardized in main IIO ABI documentation.

Suggested-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
---
 drivers/iio/adc/ad4130.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iio/adc/ad4130.c b/drivers/iio/adc/ad4130.c
index de32cc9d18c5..acc241cc0a7a 100644
--- a/drivers/iio/adc/ad4130.c
+++ b/drivers/iio/adc/ad4130.c
@@ -939,9 +939,16 @@ static const struct iio_enum ad4130_filter_mode_enum = {
 };
 
 static const struct iio_chan_spec_ext_info ad4130_filter_mode_ext_info[] = {
+	/*
+	 * Intentional duplication of attributes to keep backwards compatibility
+	 * while standardizing over the main IIO ABI for digital filtering.
+	 */
 	IIO_ENUM("filter_mode", IIO_SEPARATE, &ad4130_filter_mode_enum),
 	IIO_ENUM_AVAILABLE("filter_mode", IIO_SHARED_BY_TYPE,
 			   &ad4130_filter_mode_enum),
+	IIO_ENUM("filter_type", IIO_SEPARATE, &ad4130_filter_mode_enum),
+	IIO_ENUM_AVAILABLE("filter_type", IIO_SHARED_BY_TYPE,
+			   &ad4130_filter_mode_enum),
 	{ }
 };
 
-- 
2.47.2

Re: [PATCH v4 0/3] Re-add filter_type/filter_mode

[Jonathan Cameron]

On Tue, 4 Feb 2025 12:00:16 -0300
Marcelo Schmitt <marcelo.schmitt@analog.com> wrote:

> Better document sysfs ABI for ADC digital filter configuration.
> Also update ad4130 driver to support the standardized IIO ABI for digital filter
> configuration.
Applied to the togreg branch of iio.git and pushed out as testing.

Thanks,

Jonathan

> 
> Change log v3 -> v4
> - Renamed in_voltage-voltage_filter_mode_available to
>   in_voltage-voltage_filter_type_available instead of just removing the mode
>   variant from sysfs-bus-iio.
> - Added comment about backwards compatibility near ad4130 filter attribute
>   declarations.
> - Reordered patches so attributes are documented before use.
> - Minor re-word of in_voltage-voltage_filter_mode_available text in
>   sysfs-bus-iio-adc-ad4130 to make it more generic.
> - Picked up review tags.
> 
> Change log v2 -> v3
> - Added in_voltageY-voltageZ_filter_type to main IIO ADI doc too.
> - Added filter_type attributes to ad4130 driver so it also supports the
>   standardized ABI for digital filter configuration.
> - No longer dropping AD4130 specific filter_type_available options from sysfs-bus-iio.
> - Re-add sysfs-bus-iio-adc-ad4130 just mentioning the ABI at sysfs-bus-iio instead
>   of repeating the doc.
> 
> Change log v1 -> v2
> - Split into 3 patches.
> - Re-added sysfs-bus-iio-adc-ad4130 to keep filter_mode separate from filter_type.
> - Removed in_voltage-voltage_filter_mode_available from sysfs-bus-iio.
> - Added deprecation notes in sysfs-bus-iio-adc-ad4130 asking to use filter_type
>   for new drivers and referencing sysfs-bus-iio.
> - Improved commit message with explanation about use of filter type attributes.
> - Dropped AD4130 specific filter_type_available options from sysfs-bus-iio.
> 
> Link to v1: https://lore.kernel.org/linux-iio/b2132bd3ca1d64cdd8d5afab1f1f33c574718b50.1732901318.git.marcelo.schmitt@analog.com/
> Link to v2: https://lore.kernel.org/linux-iio/cover.1736261047.git.marcelo.schmitt@analog.com/
> Link to v3: https://lore.kernel.org/linux-iio/cover.1738608986.git.marcelo.schmitt@analog.com/
> 
> 
> Marcelo Schmitt (3):
>   Documentation: ABI: IIO: Add filter_type documentation
>   Documentation: ABI: IIO: Re-add sysfs-bus-iio-adc-ad4130
>   iio: adc: ad4130: Add filter_type attributes
> 
>  Documentation/ABI/testing/sysfs-bus-iio       | 10 +++++++++-
>  .../ABI/testing/sysfs-bus-iio-adc-ad4130      | 20 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  drivers/iio/adc/ad4130.c                      |  7 +++++++
>  4 files changed, 37 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130
> 
> 
> base-commit: 9b75dd1b7d6b98699a104c6b1eec0c8817e5fd4b