[PATCH v2 4/4] iio:filter:admv8818: Add sysfs ABI documentation

[Antoniu Miclaus <antoniu.miclaus@analog.com>]

Add initial ABI documentation for admv8818 filter sysfs interfaces.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
changes in v2:
 - remove bandwidth/center frequency related custom device attributes
 - remove bypass filter mode
 .../ABI/testing/sysfs-bus-iio-filter-admv8818 | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818 b/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
new file mode 100644
index 000000000000..7211b5d0daa0
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
@@ -0,0 +1,44 @@
+What:		/sys/bus/iio/devices/iio:deviceX/out_altvoltageY_filter_high_pass_3db_frequency
+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The cut-off frequency of the ADMV8818 high pass filter. The value is scaled using
+		the `out_altvoltageY_scale` attribute so that GHz frequencies are valid inputs,
+		The accepted range of values for the frequencies is between 1.75GHz and 19.9GHz.
+
+		The default value for the scale is 1000000, therefore MHz frequency values are
+		passed as input.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_altvoltageY_filter_low_pass_3db_frequency
+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The cut-off frequency of the ADMV8818 low pass filter. The value is scaled using
+		the `out_altvoltageY_scale` attribute so that GHz frequencies are valid inputs,
+		The accepted range of values for the frequencies is between 2.05GHz and 18.85GHz.
+
+		The default value for the scale is 1000000, therefore MHz frequency values are
+		passed as input.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_altvoltageY_scale
+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Scale high pass and lowpass filter frequency values to Hz.
+
+What:		/sys/bus/iio/devices/iio:deviceX/filter_mode_available
+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Reading this returns the valid values that can be written to the
+		on_altvoltage0_mode attribute:
+
+		- auto -> Adjust bandpass filter to track changes in input clock rate.
+		- manual -> disable/unregister the clock rate notifier / input clock tracking.
+
+What:		/sys/bus/iio/devices/iio:deviceX/filter_mode
+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		This attribute configures the filter mode.
+		Reading returns the actual mode.
-- 
2.34.0