lk2nd: serialno: Pass lk2nd version to the OS

lk2nd/serialno/rules.mk

@@ -5,3 +5,4 @@ MODULES += lib/libfdt
 OBJS += \
 	$(LOCAL_DIR)/mac.o \
 	$(LOCAL_DIR)/serialno.o \
+	$(LOCAL_DIR)/version.o \

lk2nd/serialno/version.c

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/* Copyright (c) 2023, Nikita Travkin <[email protected]> */
+
+#include <boot.h>
+#include <libfdt.h>
+
+#include <lk2nd/version.h>
+
+/*
+ * version.c - Pass lk2nd build information to the OS.
+ *
+ * Per DT spec /chosen is used for various firmware
+ * parameters so we place our version here in case OS wants
+ * to use these to i.e. OTA update the lk2nd.
+ */
+
+#define xstr(s) str(s)
+#define str(s) #s
+
+static int lk2nd_version_dt_update(void *dtb, const char *cmdline,
+				    enum boot_type boot_type)
+{
+	int ret, offset;
+
+	if (boot_type & (BOOT_DOWNSTREAM | BOOT_LK2ND))
+		return 0;
+
+	offset = fdt_path_offset(dtb, "/chosen");
+	if (offset < 0)
+		return 0;
+
+	ret = fdt_setprop_string(dtb, offset, "lk2nd,project", xstr(BOARD));
+	if (ret < 0)
+		return 0;
+
+	ret = fdt_setprop_string(dtb, offset, "lk2nd,version", xstr(LK2ND_VERSION));
+	if (ret < 0)
+		return 0;
+
+	return 0;
+}
+DEV_TREE_UPDATE(lk2nd_version_dt_update);