soc/amd/picasso: Allow use of pre-built PSP verstage

To use a signed PSP verstage, we're going to need to build it first,
then sign and store the binary.  This patch allows the stored (signed)
verstage binary to be used.

BUG=b:166108929
TEST=Build with existing verstage binary instead of re-building it.
BRANCH=Zork

Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: I5cbceca3b75f05c5460190b1c829d1ffaab2c736
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44988
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Eric Peers <epeers@google.com>

src/soc/amd/picasso/Kconfig

@@ -490,6 +490,13 @@ config PSP_UNLOCK_SECURE_DEBUG
 	help
 	  Select this item to enable secure debug options in PSP.
 
+config PSP_VERSTAGE_FILE
+	string "Specify the PSP_verstage file path"
+	depends on VBOOT_STARTS_BEFORE_BOOTBLOCK
+	default "$(obj)/psp_verstage.bin"
+	help
+	  Add psp_verstage file to the build & PSP Directory Table
+
 endmenu
 
 

src/soc/amd/picasso/Makefile.inc

@@ -249,7 +249,7 @@ PSP_SHAREDMEM_BASE=$(shell printf "0x%s" $(_PSP_SHAREDMEM_BASE))
 endif
 
 # type = 0x52 - PSP Bootloader Userspace Application (verstage)
-PSP_VERSTAGE_FILE=$(obj)/psp_verstage.bin
+PSP_VERSTAGE_FILE=$(call strip_quotes,$(CONFIG_PSP_VERSTAGE_FILE))
 endif # CONFIG_VBOOT_STARTS_BEFORE_BOOTBLOCK
 
 APOB_NV_SIZE=$(shell printf "0x%x" $(shell cat $(obj)/fmap.fmd | $(_GET_APOBNV_SIZE)))