upl: Plumb in universal payload to the init process

Read the UPL early in boot so that it is available. For now none of the
information is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Kconfig b/boot/Kconfig
index 60a4cdd..7ac3457 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -763,7 +763,9 @@
 	help
 	  Provides support for decoding a UPL-format payload into a C structure
 	  which can be used elsewhere in U-Boot. This is just the reading
-	  implementation, useful for trying it out.
+	  implementation, useful for trying it out. See UPL_IN for how
+	  to tell U-Boot to actually read it on startup and use it for memory
+	  and device information, etc.
 
 config UPL_WRITE
 	bool "upl - Support writing a Universal Payload handoff"
@@ -774,6 +776,14 @@
 	  for how to tell U-Boot SPL to actually write it before jumping to
 	  the next phase.
 
+config UPL_IN
+	bool "upl - Read the UPL handoff on startup"
+	select UPL_READ
+	help
+	  Read an SPL handoff when U-Boot starts and use it to provide
+	  devices, memory layout, etc. required by U-Boot. This allows U-Boot
+	  to function as a payload in the meaning of the specification.
+
 if SPL
 
 config SPL_UPL