scripts: imgtool: Add script to combine multiple image as single

MCUBoot multi image support mode requires each image
be procedded individually that requires multiple signature
check during boot. If there be 4 imageis it requires 4 times
signature validatation. This feature increase boot time.
Depend on the project requirement long boot time may not be accepted.

To provide a solution for this case we propose to
- Generate each image as regular mcuboot format
- Concatanate them and re generate a main mcuboot image. As below

-------------------------
|         Header        |
-------------------------
|        Image-1        |
|  (Header+Data+Footer) |
-------------------------
|        Image-2        |
|  (Header+Data+Footer) |
-------------------------
|        .....          |
-------------------------
|         Footer        |
-------------------------

During boot time if top level image be validated sub image can be
just copied to the target location without to recheck them.

There will be two commit to implement this feature
1- Add a script that combine images
2- Update mcuboot source code to process subimages

This commit is for #1, it adds a script which called as
combine_images.py. Any imgtool parameters can be passed to the script
It will directly pass them to the imgtool.

Usage:
python combine_images.py --config combine_images.yaml --imgtool imgtool --output <outfolder>

combine_images.yaml file is added as reference file it need to be
updated as per of the project need.

Signed-off-by: Sadik Ozer <[email protected]>
Signed-off-by: Michael Eskowitz <[email protected]>

Author: Michael Eskowitz

scripts/combine_images.py

@@ -0,0 +1,137 @@
+#! /usr/bin/env python3
+#
+# Copyright (C) 2025 Analog Devices, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import os
+import pathlib
+import subprocess
+import sys
+
+import yaml
+import shutil
+
+
+def main():
+    global img_tool
+    global output_dir
+    global config_path
+
+    parser = argparse.ArgumentParser(description="Create application package", allow_abbrev=False)
+    parser.add_argument('--config', help="The path to config yaml file", required=True)
+    parser.add_argument('--imgtool', help="The path to ImgTool", required=True)
+    parser.add_argument('--output', help="Output directory", required=True)
+
+    args = parser.parse_args()
+
+    if not os.path.isfile(args.config):
+        print(f"Error: The config file '{args.config}' does not exist")
+        return
+
+    config_path = os.path.dirname(os.path.abspath(args.config))
+    print(f"config_path: {config_path}")
+
+    with open(args.config) as config_file:
+        config = yaml.safe_load(config_file)
+
+    img_tool = args.imgtool
+    if img_tool.endswith('.py'):
+        if not os.path.exists(img_tool): # Is python file exist?
+            print(f"Error: The '{img_tool}' not found")
+            return
+    else:
+        if not shutil.which(img_tool): # Is binary file exist?
+            print(f"Error: The '{img_tool}' not found in the path")
+            return
+
+
+    output_dir = args.output
+    os.makedirs(output_dir, exist_ok=True)
+
+    parse_app_pack(config, None)
+
+    print(f"\nCreated {package_name}")
+
+
+def verify_file_exists(filename):
+    filepath = pathlib.Path(filename)
+
+    if not filepath.exists():
+        print("ERROR: File " + filename + " not found")
+        sys.exit(1)
+
+
+def parse_app_pack(app_pack, name):
+    params = None
+    image = []
+    global package_name
+
+    for key in app_pack:
+        if key.endswith("_pack"):
+            imagename = parse_app_pack(app_pack[key], name)
+            image += [imagename]
+        if key.lower() == "params":
+            params = app_pack[key]
+        if key.lower() == "infile":
+            if app_pack[key] != "":
+                image_path = os.path.join(config_path, app_pack[key])
+                verify_file_exists(image_path)
+                image += [image_path]
+        if key.lower() == "outfile":
+            name = app_pack[key]
+
+    # Exit if params or image are not specified
+    if (params is None) or (image is None):
+        return None
+
+    cmd = []
+    if img_tool.endswith('.py'):
+        cmd += [sys.executable]
+    
+    cmd += [img_tool]
+    cmd += ["sign"]
+    cmd += params.split()
+
+    # Combine images for parent package (top level package)
+    if len(image) > 1:
+        combined_images = os.path.join(output_dir, "combined.bin")
+
+        with open(combined_images, 'wb') as outfile:
+            for fname in image:
+                with open(fname, 'rb') as infile:
+                    outfile.write(infile.read())
+                    infile.close()
+            outfile.close()
+
+        image_input = combined_images
+    else:
+        image_input = image[0]
+
+    image_output = os.path.join(output_dir, name)
+
+    cmd += [image_input]
+    cmd += [image_output]
+
+    print(f'Calling imgtool to generate file {image_output}')
+    package_name = image_output
+    subprocess.run(cmd)
+
+    return image_output
+
+
+if __name__ == "__main__":
+    main()

scripts/combine_images.yaml

@@ -0,0 +1,36 @@
+#
+# Copyright (C) 2025 Analog Devices, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+img0_pack:
+    outfile: combined_signed.bin
+    params: "--key ../root-rsa-2048.pem --header-size 0x20 --align 4 --load-addr 0x20080000 --pad-header --version 1.0.0 --slot-size 0x100000"
+
+    img1_pack:
+        infile: img1.bin
+        outfile: img1_signed.bin
+        params: "--key ../root-rsa-2048.pem --header-size 0x20 --align 4 --load-addr 0x20010000 --pad-header --version 1.0.0 --slot-size 0x10000"
+
+    img2_pack:
+        infile: img2.bin
+        outfile: img2_signed.bin
+        params: "--key ../root-rsa-2048.pem --header-size 0x20 --align 4 --load-addr 0x20020000 --pad-header --version 1.0.0 --slot-size 0x10000"
+
+    img3_pack:
+        infile: img3.bin
+        outfile: img3_signed.bin
+        params: "--key ../root-rsa-2048.pem --header-size 0x20 --align 4 --load-addr 0x20030000 --pad-header --version 1.0.0 --slot-size 0x10000"