dtoc: Add support for reading fixed-length bytes properties

Add functions to read a sequence of bytes from the devicetree.

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

tools/dtoc/fdt_util.py

@@ -202,6 +202,26 @@ def GetByte(node, propname, default=None):
                          (node.name, propname, len(value), 1))
     return ord(value[0])
 
+def GetBytes(node, propname, size, default=None):
+    """Get a set of bytes from a property
+
+    Args:
+        node (Node): Node object to read from
+        propname (str): property name to read
+        size (int): Number of bytes to expect
+        default (bytes): Default value or None
+
+    Returns:
+        bytes: Bytes value read, or default if none
+    """
+    prop = node.props.get(propname)
+    if not prop:
+        return default
+    if len(prop.bytes) != size:
+        raise ValueError("Node '%s' property '%s' has length %d, expecting %d" %
+                         (node.name, propname, len(prop.bytes), size))
+    return prop.bytes
+
 def GetPhandleList(node, propname):
     """Get a list of phandles from a property
 

tools/dtoc/test_fdt.py

@@ -635,6 +635,23 @@ class TestFdtUtil(unittest.TestCase):
         self.assertIn("property 'intval' has length 4, expecting 1",
                       str(e.exception))
 
+    def testGetBytes(self):
+        self.assertEqual(bytes([5]), fdt_util.GetBytes(self.node, 'byteval', 1))
+        self.assertEqual(None, fdt_util.GetBytes(self.node, 'missing', 3))
+        self.assertEqual(
+            bytes([3]), fdt_util.GetBytes(self.node, 'missing', 3,  bytes([3])))
+
+        with self.assertRaises(ValueError) as e:
+            fdt_util.GetBytes(self.node, 'longbytearray', 7)
+        self.assertIn(
+            "Node 'spl-test' property 'longbytearray' has length 9, expecting 7",
+             str(e.exception))
+
+        self.assertEqual(
+            bytes([0, 0, 0, 1]), fdt_util.GetBytes(self.node, 'intval', 4))
+        self.assertEqual(
+            bytes([3]), fdt_util.GetBytes(self.node, 'missing', 3,  bytes([3])))
+
     def testGetPhandleList(self):
         dtb = fdt.FdtScan(find_dtb_file('dtoc_test_phandle.dts'))
         node = dtb.GetNode('/phandle-source2')