[PATCH v2 2/2] uboot-sign: Add support for setting firmware property in FIT configuration

[Jamin Lin <jamin_lin@aspeedtech.com>]

Add the ability to set the "firmware" property in the FIT configuration node
by introducing the UBOOT_FIT_CONF_FIRMWARE variable.

This property defines the primary image to be executed during boot. If it is
set, its value will be written into the FIT configuration under the "firmware"
field. If not set, the bootloader will fall back to using the first entry in
the "loadables" list.

Using this property improves control over the boot sequence, especially in
multi-binary boot scenarios.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 meta/classes-recipe/uboot-sign.bbclass | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/meta/classes-recipe/uboot-sign.bbclass b/meta/classes-recipe/uboot-sign.bbclass
index dcf94b7179..283b68759d 100644
--- a/meta/classes-recipe/uboot-sign.bbclass
+++ b/meta/classes-recipe/uboot-sign.bbclass
@@ -101,6 +101,10 @@ UBOOT_FIT_TEE_IMAGE ?= "tee-raw.bin"
 # User specific settings
 UBOOT_FIT_USER_SETTINGS ?= ""
 
+# Sets the firmware property to select the image to boot first.
+# If not set, the first entry in "loadables" is used instead.
+UBOOT_FIT_CONF_FIRMWARE ?= ""
+
 # Unit name containing a list of users additional binaries to be loaded.
 # It is a comma-separated list of strings.
 UBOOT_FIT_CONF_USER_LOADABLES ?= ''
@@ -361,6 +365,7 @@ EOF
 # we want to sign it so that the SPL can verify it
 uboot_fitimage_assemble() {
 	conf_loadables="\"uboot\""
+	conf_firmware=""
 	rm -f ${UBOOT_ITS} ${UBOOT_FITIMAGE_BINARY}
 
 	# First we create the ITS script
@@ -432,6 +437,10 @@ EOF
 		conf_loadables="${conf_loadables}${UBOOT_FIT_CONF_USER_LOADABLES}"
 	fi
 
+    if [ -n "${UBOOT_FIT_CONF_FIRMWARE}" ] ; then
+		conf_firmware="firmware = \"${UBOOT_FIT_CONF_FIRMWARE}\";"
+	fi
+
 	cat << EOF >> ${UBOOT_ITS}
     };
 
@@ -439,6 +448,7 @@ EOF
         default = "conf";
         conf {
             description = "Boot with signed U-Boot FIT";
+            ${conf_firmware}
             loadables = ${conf_loadables};
             fdt = "fdt";
         };
-- 
2.43.0