[v3 09/13] iio: document "serial_number" sysfs attribute

[Andrea Merello]

This patch adds ABI documentation for the new "serial_number" sysfs
attribute. The first user is the bno055 IIO driver.

Signed-off-by: Andrea Merello <andrea.merello@xxxxxx>
---
 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 1b8d77577608..224585f00147 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2017,3 +2017,10 @@ Contact:	linux-iio@xxxxxxxxxxxxxxx
 Description:
 		Raw (unscaled) euler angles readings. Units after
 		application of scale are deg.
+
+What:		/sys/bus/iio/devices/iio:deviceX/serial_number
+KernelVersion:	5.17
+Contact:	linux-iio@xxxxxxxxxxxxxxx
+Description:
+		16-bytes, 2-digits-per-byte, HEX-string representing the sensor
+		unique ID number.
-- 
2.17.1