boot/arm-trusted-firmware: allow using Barebox as BL33

Since version 2022.04.0, Barebox now supports a generic image built
for platforms, to be used as BL33 to generate FIP images. This patch
makes it available as a choice of BL33 to be used with ATF and is
based on the similar work put into U-Boot as BL33.

Signed-off-by: Casey Reeves <casey@xogium.me>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

boot/arm-trusted-firmware/Config.in

@@ -129,6 +129,27 @@ config BR2_TARGET_ARM_TRUSTED_FIRMWARE_BL32_OPTEE
 
 endchoice
 
+config BR2_TARGET_ARM_TRUSTED_FIRMWARE_BAREBOX_AS_BL33
+	bool "Use Barebox as BL33"
+	depends on BR2_TARGET_BAREBOX
+	help
+	  This option allows to embed the Barebox generic BL33 image in
+	  the ARM Trusted Firmware. It ensures that the Barebox package
+	  gets built before ATF, and that the appropriate BL33
+	  variable pointing to the generic bl33 image is passed
+	  when building ATF.
+
+if BR2_TARGET_ARM_TRUSTED_FIRMWARE_BAREBOX_AS_BL33
+
+config BR2_TARGET_ARM_TRUSTED_FIRMWARE_BAREBOX_BL33_IMAGE
+	string "Barebox BL33 image name"
+	default "*-generic-bl33.img"
+	help
+	  Name of the Barebox BL33 image to include in ATF, it must
+	  have been installed to BINARIES_DIR by the Barebox package.
+
+endif
+
 config BR2_TARGET_ARM_TRUSTED_FIRMWARE_UBOOT_AS_BL33
 	bool "Use U-Boot as BL33"
 	depends on BR2_TARGET_UBOOT

boot/arm-trusted-firmware/arm-trusted-firmware.mk

@@ -105,6 +105,12 @@ ARM_TRUSTED_FIRMWARE_MAKE_OPTS += AARCH32_SP=optee
 endif
 endif # BR2_TARGET_ARM_TRUSTED_FIRMWARE_BL32_OPTEE
 
+ifeq ($(BR2_TARGET_ARM_TRUSTED_FIRMWARE_BAREBOX_AS_BL33),y)
+ARM_TRUSTED_FIRMWARE_BAREBOX_BIN = $(call qstrip,$(BR2_TARGET_ARM_TRUSTED_FIRMWARE_BAREBOX_BL33_IMAGE))
+ARM_TRUSTED_FIRMWARE_MAKE_OPTS += BL33=$(BINARIES_DIR)/$(ARM_TRUSTED_FIRMWARE_BAREBOX_BIN)
+ARM_TRUSTED_FIRMWARE_DEPENDENCIES += barebox
+endif
+
 ifeq ($(BR2_TARGET_ARM_TRUSTED_FIRMWARE_EDK2_AS_BL33),y)
 ARM_TRUSTED_FIRMWARE_DEPENDENCIES += edk2
 # Since the flash device name vary between platforms, we use the variable