env: allow environment to be amended from control dtb
It can be useful to use the same U-Boot binary for multiple purposes,
say the normal one, one for developers that allow breaking into the
U-Boot shell, and one for use during bootstrapping which runs a
special-purpose bootcmd. Or one can have several board variants that
can share almost all boot logic, but just needs a few tweaks in the
variables used by the boot script.
To that end, allow the control dtb to contain a /config/enviroment
node (or whatever one puts in fdt_env_path variable), whose
property/value pairs are used to update the run-time environment after
it has been loaded from its persistent location.
The indirection via fdt_env_path is for maximum flexibility - for
example, should the user wish (or board logic dictate) that the values
in the DTB should no longer be applied, one simply needs to delete the
fdt_env_path variable; that can even be done automatically by
including a
fdt_env_path = "";
property in the DTB node.
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/env/Kconfig b/env/Kconfig
index 1b7906c..1411f9e 100644
--- a/env/Kconfig
+++ b/env/Kconfig
@@ -670,6 +670,24 @@
later by U-Boot code. With CONFIG_OF_CONTROL this is instead
controlled by the value of /config/load-environment.
+config ENV_IMPORT_FDT
+ bool "Amend environment by FDT properties"
+ depends on OF_CONTROL
+ help
+ If selected, after the environment has been loaded from its
+ persistent location, the "env_fdt_path" variable is looked
+ up and used as a path to a node in the control DTB. The
+ property/value pairs in that node is then used to update the
+ run-time environment. This can be useful to use the same
+ U-Boot binary with different board variants.
+
+config ENV_FDT_PATH
+ string "Default value for env_fdt_path variable"
+ depends on ENV_IMPORT_FDT
+ default "/config/environment"
+ help
+ The initial value of the env_fdt_path variable.
+
config ENV_APPEND
bool "Always append the environment with new data"
default n