iio:filter:admv8818: Add sysfs ABI documentation

Add initial ABI documentation for admv8818 filter sysfs interfaces.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818 b/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
new file mode 100644 (file)
index 0000000..f6c0357
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-filter-admv8818
@@ -0,0 +1,16 @@
+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.