Documentation: ABI: IIO: Re-add sysfs-bus-iio-adc-ad4130

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 <[e-mail]>
Reviewed-by: David Lechner <[e-mail]>
Link: https://patch.msgid.link/c77b2d6[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/ABI/testing/sysfs-bus-iio

···
 		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:	[e-mail]
 Description:

Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130

···
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltage-voltage_filter_mode_available
+KernelVersion:  6.2
+Contact:	[e-mail]
+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:	[e-mail]
+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.

MAINTAINERS

···
 L:	[e-mail]
 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