upl: Add support for reading a upl handoff

Universal Payload provides a standard way of handing off control between
two firmware phases. Add support for reading the handoff information into
a structure.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/upl_common.h b/boot/upl_common.h
new file mode 100644
index 0000000..cc517dc
--- /dev/null
+++ b/boot/upl_common.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * UPL handoff command functions
+ *
+ * Copyright 2024 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __UPL_COMMON_H
+#define __UPL_COMMON_H
+
+/* Names of bootmodes */
+extern const char *const bootmode_names[UPLBM_COUNT];
+
+/* Names of memory usages */
+extern const char *const usage_names[UPLUS_COUNT];
+
+/* Names of access types */
+extern const char *const access_types[UPLUS_COUNT];
+
+/* Names of graphics formats */
+extern const char *const graphics_formats[UPLUS_COUNT];
+
+#endif /* __UPL_COMMON_H */