binman: Produce a template-file after processing

This file aids debugging when binman fails to get far enough to write out
the final devicetree file. Write it immediate after template processing.

Signed-off-by: Simon Glass <sjg@chromium.org>

3 files changed, 25 insertions, 2 deletions

diff --git a/tools/binman/binman.rst b/tools/binman/binman.rst
index 8f57b6cfc76..67bc3e87531 100644
--- a/tools/binman/binman.rst
+++ b/tools/binman/binman.rst
@@ -1256,6 +1256,10 @@ Properties in the template node are inserted into the destination node if they
 do not exist there. In the example above, `some-property` is added to each of
 `spi-image` and `mmc-image`.
 
+The initial devicetree produced by the templating process is written to the
+`u-boot.dtb.tmpl1` file. This can be useful to see what is going on if there is
+a failure before the final `u-boot.dtb.out` file is written.
+
 Note that template nodes are not removed from the binman description at present.
 
 
diff --git a/tools/binman/control.py b/tools/binman/control.py
index 2aa6307750e..963f9b96638 100644
--- a/tools/binman/control.py
+++ b/tools/binman/control.py
@@ -494,6 +494,9 @@ def _ProcessTemplates(parent):
     Args:
         parent: Binman node to process (typically /binman)
 
+    Returns:
+        bool: True if any templates were processed
+
     Search though each target node looking for those with an 'insert-template'
     property. Use that as a list of references to template nodes to use to
     adjust the target node.
@@ -506,11 +509,15 @@ def _ProcessTemplates(parent):
 
     See 'Templates' in the Binman documnentation for details.
     """
+    found = False
     for node in parent.subnodes:
         tmpl = fdt_util.GetPhandleList(node, 'insert-template')
         if tmpl:
             node.copy_subnodes_from_phandles(tmpl)
-        _ProcessTemplates(node)
+            found = True
+
+        found |= _ProcessTemplates(node)
+    return found
 
 def PrepareImagesAndDtbs(dtb_fname, select_images, update_fdt, use_expanded):
     """Prepare the images to be processed and select the device tree
@@ -554,7 +561,10 @@ def PrepareImagesAndDtbs(dtb_fname, select_images, update_fdt, use_expanded):
         raise ValueError("Device tree '%s' does not have a 'binman' "
                             "node" % dtb_fname)
 
-    _ProcessTemplates(node)
+    if _ProcessTemplates(node):
+        dtb.Sync(True)
+        fname = tools.get_output_filename('u-boot.dtb.tmpl1')
+        tools.write_file(fname, dtb.GetContents())
 
     images = _ReadImageDesc(node, use_expanded)
 
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index 0e026ecc31a..b15f5acc7c0 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -6862,6 +6862,15 @@ fdt         fdtmap                Extract the devicetree blob from the fdtmap
         second = U_BOOT_DATA + b'#' + VGA_DATA + U_BOOT_DTB_DATA
         self.assertEqual(U_BOOT_IMG_DATA + first + second, data)
 
+        dtb_fname1 = tools.get_output_filename('u-boot.dtb.tmpl1')
+        self.assertTrue(os.path.exists(dtb_fname1))
+        dtb = fdt.Fdt.FromData(tools.read_file(dtb_fname1))
+        dtb.Scan()
+        node1 = dtb.GetNode('/binman/template')
+        self.assertTrue(node1)
+        vga = dtb.GetNode('/binman/first/intel-vga')
+        self.assertTrue(vga)
+
     def testTemplateBlobMulti(self):
         """Test using a template with 'multiple-images' enabled"""
         TestFunctional._MakeInputFile('my-blob.bin', b'blob')