diff --git a/test/py/u_boot_console_base.py b/test/py/u_boot_console_base.py
index 433bec6..06f61f9 100644
--- a/test/py/u_boot_console_base.py
+++ b/test/py/u_boot_console_base.py
@@ -215,6 +215,25 @@
         self.log.action('Sending Ctrl-C')
         self.run_command(chr(3), wait_for_echo=False, send_nl=False)
 
+    def wait_for(self, text):
+        '''Wait for a pattern to be emitted by U-Boot.
+
+        This is useful when a long-running command such as "dfu" is executing,
+        and it periodically emits some text that should show up at a specific
+        location in the log file.
+
+        Args:
+            text: The text to wait for; either a string (containing raw text,
+                not a regular expression) or an re object.
+
+        Returns:
+            Nothing.
+        '''
+
+        if type(text) == type(''):
+            text = re.escape(text)
+        self.p.expect([text])
+
     def drain_console(self):
         '''Read from and log the U-Boot console for a short time.
 
diff --git a/test/py/u_boot_utils.py b/test/py/u_boot_utils.py
new file mode 100644
index 0000000..539af61
--- /dev/null
+++ b/test/py/u_boot_utils.py
@@ -0,0 +1,171 @@
+# Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+#
+# SPDX-License-Identifier: GPL-2.0
+
+# Utility code shared across multiple tests.
+
+import hashlib
+import os
+import os.path
+import sys
+import time
+
+def md5sum_data(data):
+    '''Calculate the MD5 hash of some data.
+
+    Args:
+        data: The data to hash.
+
+    Returns:
+        The hash of the data, as a binary string.
+    '''
+
+    h = hashlib.md5()
+    h.update(data)
+    return h.digest()
+
+def md5sum_file(fn, max_length=None):
+    '''Calculate the MD5 hash of the contents of a file.
+
+    Args:
+        fn: The filename of the file to hash.
+        max_length: The number of bytes to hash. If the file has more
+            bytes than this, they will be ignored. If None or omitted, the
+            entire file will be hashed.
+
+    Returns:
+        The hash of the file content, as a binary string.
+    '''
+
+    with open(fn, 'rb') as fh:
+        if max_length:
+            params = [max_length]
+        else:
+            params = []
+        data = fh.read(*params)
+    return md5sum_data(data)
+
+class PersistentRandomFile(object):
+    '''Generate and store information about a persistent file containing
+    random data.'''
+
+    def __init__(self, u_boot_console, fn, size):
+        '''Create or process the persistent file.
+
+        If the file does not exist, it is generated.
+
+        If the file does exist, its content is hashed for later comparison.
+
+        These files are always located in the "persistent data directory" of
+        the current test run.
+
+        Args:
+            u_boot_console: A console connection to U-Boot.
+            fn: The filename (without path) to create.
+            size: The desired size of the file in bytes.
+
+        Returns:
+            Nothing.
+        '''
+
+        self.fn = fn
+
+        self.abs_fn = u_boot_console.config.persistent_data_dir + '/' + fn
+
+        if os.path.exists(self.abs_fn):
+            u_boot_console.log.action('Persistent data file ' + self.abs_fn +
+                ' already exists')
+            self.content_hash = md5sum_file(self.abs_fn)
+        else:
+            u_boot_console.log.action('Generating ' + self.abs_fn +
+                ' (random, persistent, %d bytes)' % size)
+            data = os.urandom(size)
+            with open(self.abs_fn, 'wb') as fh:
+                fh.write(data)
+            self.content_hash = md5sum_data(data)
+
+def attempt_to_open_file(fn):
+    '''Attempt to open a file, without throwing exceptions.
+
+    Any errors (exceptions) that occur during the attempt to open the file
+    are ignored. This is useful in order to test whether a file (in
+    particular, a device node) exists and can be successfully opened, in order
+    to poll for e.g. USB enumeration completion.
+
+    Args:
+        fn: The filename to attempt to open.
+
+    Returns:
+        An open file handle to the file, or None if the file could not be
+            opened.
+    '''
+
+    try:
+        return open(fn, 'rb')
+    except:
+        return None
+
+def wait_until_open_succeeds(fn):
+    '''Poll until a file can be opened, or a timeout occurs.
+
+    Continually attempt to open a file, and return when this succeeds, or
+    raise an exception after a timeout.
+
+    Args:
+        fn: The filename to attempt to open.
+
+    Returns:
+        An open file handle to the file.
+    '''
+
+    for i in xrange(100):
+        fh = attempt_to_open_file(fn)
+        if fh:
+            return fh
+        time.sleep(0.1)
+    raise Exception('File could not be opened')
+
+def wait_until_file_open_fails(fn, ignore_errors):
+    '''Poll until a file cannot be opened, or a timeout occurs.
+
+    Continually attempt to open a file, and return when this fails, or
+    raise an exception after a timeout.
+
+    Args:
+        fn: The filename to attempt to open.
+        ignore_errors: Indicate whether to ignore timeout errors. If True, the
+            function will simply return if a timeout occurs, otherwise an
+            exception will be raised.
+
+    Returns:
+        Nothing.
+    '''
+
+    for i in xrange(100):
+        fh = attempt_to_open_file(fn)
+        if not fh:
+            return
+        fh.close()
+        time.sleep(0.1)
+    if ignore_errors:
+        return
+    raise Exception('File can still be opened')
+
+def run_and_log(u_boot_console, cmd, ignore_errors=False):
+    '''Run a command and log its output.
+
+    Args:
+        u_boot_console: A console connection to U-Boot.
+        cmd: The command to run, as an array of argv[].
+        ignore_errors: Indicate whether to ignore errors. If True, the function
+            will simply return if the command cannot be executed or exits with
+            an error code, otherwise an exception will be raised if such
+            problems occur.
+
+    Returns:
+        Nothing.
+    '''
+
+    runner = u_boot_console.log.get_runner(cmd[0], sys.stdout)
+    runner.run(cmd, ignore_errors=ignore_errors)
+    runner.close()