binman: Support locating an FDT map

Add support for locating an image's Fdt map which is used to determine
the contents and structure of the image.

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

tools/binman/etype/fdtmap.py

@@ -15,7 +15,26 @@ from fdt import Fdt
 import state
 import tools
 
-FDTMAP_MAGIC = b'_FDTMAP_'
+FDTMAP_MAGIC   = b'_FDTMAP_'
+FDTMAP_HDR_LEN = 16
+
+def LocateFdtmap(data):
+    """Search an image for an fdt map
+
+    Args:
+        data: Data to search
+
+    Returns:
+        Position of fdt map in data, or None if not found. Note that the
+            position returned is of the FDT header, i.e. before the FDT data
+    """
+    hdr_pos = data.find(FDTMAP_MAGIC)
+    size = len(data)
+    if hdr_pos != -1:
+        hdr = data[hdr_pos:hdr_pos + FDTMAP_HDR_LEN]
+        if len(hdr) == FDTMAP_HDR_LEN:
+            return hdr_pos
+    return None
 
 class Entry_fdtmap(Entry):
     """An entry which contains an FDT map
@@ -24,7 +43,9 @@ class Entry_fdtmap(Entry):
         None
 
     An FDT map is just a header followed by an FDT containing a list of all the
-    entries in the image.
+    entries in the image. The root node corresponds to the image node in the
+    original FDT, and an image-name property indicates the image name in that
+    original tree.
 
     The header is the string _FDTMAP_ followed by 8 unused bytes.
 

tools/binman/ftest.py

@@ -24,6 +24,7 @@ import command
 import control
 import elf
 import fdt
+from etype import fdtmap
 import fdt_util
 import fmap_util
 import test_util
@@ -2267,6 +2268,20 @@ class TestFunctional(unittest.TestCase):
         self.assertEqual(len(data), 0x100 + section_size)
         self.assertEqual(section_size, 0x400 + dtb_size)
 
+    def testFindFdtmap(self):
+        """Test locating an FDT map in an image"""
+        self._CheckLz4()
+        data = self.data = self._DoReadFileRealDtb('128_decode_image.dts')
+        image = control.images['image']
+        entries = image.GetEntries()
+        entry = entries['fdtmap']
+        self.assertEqual(entry.image_pos, fdtmap.LocateFdtmap(data))
+
+    def testFindFdtmapMissing(self):
+        """Test failing to locate an FDP map"""
+        data = self._DoReadFile('005_simple.dts')
+        self.assertEqual(None, fdtmap.LocateFdtmap(data))
+
 
 if __name__ == "__main__":
     unittest.main()

tools/binman/test/128_decode_image.dts

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		size = <0xc00>;
+		u-boot {
+		};
+		section {
+			align = <0x100>;
+			cbfs {
+				size = <0x400>;
+				u-boot {
+					cbfs-type = "raw";
+				};
+				u-boot-dtb {
+					cbfs-type = "raw";
+					cbfs-compress = "lzma";
+					cbfs-offset = <0x80>;
+				};
+			};
+			u-boot-dtb {
+				compress = "lz4";
+			};
+		};
+		fdtmap {
+		};
+		image-header {
+			location = "end";
+		};
+	};
+};