board: sl28: add update image documentation

Document the update image and how to use the EFI UpdateCapsule.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

diff --git a/doc/board/kontron/sl28.rst b/doc/board/kontron/sl28.rst
index 07431986d8fd7a9c1ddb926b287847aa89b10c13..c7b18bed10c4b886a4b78adfbf01989929d25796 100644 (file)
--- a/doc/board/kontron/sl28.rst
+++ b/doc/board/kontron/sl28.rst
@@ -52,6 +52,21 @@ Disable the builtin watchdog
 - power-cycle the board
 
 
+Update image
+------------
+
+After the build finished, there will be an update image called
+u-boot.update. This can either be used in the DFU mode (which isn't
+supported yet) or encapsulated in an EFI UpdateCapsule.
+
+To build the capsule use the following command
+
+ $ tools/mkeficapsule -f u-boot.update -i 1 UpdateUboot
+
+Afterward you can copy this file to your ESP into the /EFI/UpdateCapsule/
+folder. On the next EFI boot this will automatically update your
+bootloader.
+
 Useful I2C tricks
 -----------------