[v6 10/14] iio: document "serialnumber" sysfs attribute

[andrea.merello]

From: Andrea Merello <andrea.merello@xxxxxx>

Add ABI documentation for the new "serialnumber" sysfs attribute. The
first user is the bno055 IIO driver.

Signed-off-by: Andrea Merello <andrea.merello@xxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-bus-iio | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 2f54f26d9e59..03e29517c1a4 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2053,3 +2053,10 @@ Contact:	linux-iio@xxxxxxxxxxxxxxx
 Description:
 		Raw (unscaled) euler angles readings. Units after
 		application of scale are deg.
+
+What:		/sys/bus/iio/devices/iio:deviceX/serialnumber
+KernelVersion:	5.20
+Contact:	linux-iio@xxxxxxxxxxxxxxx
+Description:
+		An example format is 16-bytes, 2-digits-per-byte, HEX-string
+		representing the sensor unique ID number.
-- 
2.17.1