1 files changed, 44 insertions, 0 deletions
diff --git a/tools/binman/etype/u_boot_tpl_bss_pad.py b/tools/binman/etype/u_boot_tpl_bss_pad.py
new file mode 100644
index 0000000000..521b24a384
--- /dev/null
+++ b/tools/binman/etype/u_boot_tpl_bss_pad.py
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright 2021 Google LLC
+# Written by Simon Glass <sjg@chromium.org>
+#
+# Entry-type module for BSS padding for tpl/u-boot-tpl.bin. This padding
+# can be added after the TPL binary to ensure that anything concatenated
+# to it will appear to TPL to be at the end of BSS rather than the start.
+#
+
+from binman import elf
+from binman.entry import Entry
+from binman.etype.blob import Entry_blob
+from patman import tools
+
+class Entry_u_boot_tpl_bss_pad(Entry_blob):
+    """U-Boot TPL binary padded with a BSS region
+
+    Properties / Entry arguments:
+        None
+
+    This holds the padding added after the TPL binary to cover the BSS (Block
+    Started by Symbol) region. This region holds the various variables used by
+    TPL. It is set to 0 by TPL when it starts up. If you want to append data to
+    the TPL image (such as a device tree file), you must pad out the BSS region
+    to avoid the data overlapping with U-Boot variables. This entry is useful in
+    that case. It automatically pads out the entry size to cover both the code,
+    data and BSS.
+
+    The contents of this entry will a certain number of zero bytes, determined
+    by __bss_size
+
+    The ELF file 'tpl/u-boot-tpl' must also be available for this to work, since
+    binman uses that to look up the BSS address.
+    """
+    def __init__(self, section, etype, node):
+        super().__init__(section, etype, node)
+
+    def ObtainContents(self):
+        fname = tools.GetInputFilename('tpl/u-boot-tpl')
+        bss_size = elf.GetSymbolAddress(fname, '__bss_size')
+        if not bss_size:
+            self.Raise('Expected __bss_size symbol in tpl/u-boot-tpl')
+        self.SetContents(tools.GetBytes(0, bss_size))
+        return True