[v2] dtoc: add coverage test for unicode error

diff --git a/tools/dtoc/dtb_platdata.py b/tools/dtoc/dtb_platdata.py
index c28768f4a2..f870ebdb78 100644
--- a/tools/dtoc/dtb_platdata.py
+++ b/tools/dtoc/dtb_platdata.py
@@ -145,8 +145,10 @@  class DtbPlatdata(object):
                 U_BOOT_DRIVER_ALIAS(driver_alias, driver_name)
             value: Driver name declared with U_BOOT_DRIVER(driver_name)
         _links: List of links to be included in dm_populate_phandle_data()
+        _drivers_additional: List of additional drivers to use during scanning
     """
-    def __init__(self, dtb_fname, include_disabled, warning_disabled):
+    def __init__(self, dtb_fname, include_disabled, warning_disabled,
+                 drivers_additional=[]):
         self._fdt = None
         self._dtb_fname = dtb_fname
         self._valid_nodes = None
@@ -157,6 +159,7 @@  class DtbPlatdata(object):
         self._drivers = []
         self._driver_aliases = {}
         self._links = []
+        self._drivers_additional = drivers_additional
 
     def get_normalized_compat_name(self, node):
         """Get a node's normalized compat name
@@ -338,6 +341,14 @@  class DtbPlatdata(object):
                     continue
                 self.scan_driver(dirpath + '/' + fn)
 
+        for fn in self._drivers_additional:
+            if not isinstance(fn, str) or len(fn) == 0:
+                continue
+            if fn[0] == '/':
+                self.scan_driver(fn)
+            else:
+                self.scan_driver(basedir + '/' + fn)
+
     def scan_dtb(self):
         """Scan the device tree to obtain a tree of nodes and properties
 
@@ -654,7 +665,8 @@  class DtbPlatdata(object):
 
         self.out(''.join(self.get_buf()))
 
-def run_steps(args, dtb_file, include_disabled, output, warning_disabled=False):
+def run_steps(args, dtb_file, include_disabled, output, warning_disabled=False,
+              drivers_additional=[]):
     """Run all the steps of the dtoc tool
 
     Args:
@@ -666,7 +678,7 @@  def run_steps(args, dtb_file, include_disabled, output, warning_disabled=False):
     if not args:
         raise ValueError('Please specify a command: struct, platdata')
 
-    plat = DtbPlatdata(dtb_file, include_disabled, warning_disabled)
+    plat = DtbPlatdata(dtb_file, include_disabled, warning_disabled, drivers_additional)
     plat.scan_drivers()
     plat.scan_dtb()
     plat.scan_tree()
diff --git a/tools/dtoc/dtoc_test_scan_drivers.cxx b/tools/dtoc/dtoc_test_scan_drivers.cxx
new file mode 100644
index 0000000000..557c692ba2
--- /dev/null
+++ b/tools/dtoc/dtoc_test_scan_drivers.cxx
@@ -0,0 +1 @@ 
+U_BOOT_DRIVER_ALIAS(sandbox_gpio, sandbox_gpio_alias2)
diff --git a/tools/dtoc/test_dtoc.py b/tools/dtoc/test_dtoc.py
index 169ecd6e6e..f1b0eb824a 100755
--- a/tools/dtoc/test_dtoc.py
+++ b/tools/dtoc/test_dtoc.py
@@ -13,6 +13,7 @@  import collections
 import os
 import struct
 import sys
+import tempfile
 import unittest
 
 from dtoc import dtb_platdata
@@ -829,3 +830,28 @@  U_BOOT_DEVICE(spl_test2) = {
             self.run_test(['invalid-cmd'], dtb_file, output)
         self.assertIn("Unknown command 'invalid-cmd': (use: struct, platdata)",
                       str(e.exception))
+
+    def testScanDrivers(self):
+        """Test running dtoc with additional drivers to scan"""
+        dtb_file = get_dtb_file('dtoc_test_simple.dts')
+        output = tools.GetOutputFilename('output')
+        with test_util.capture_sys_output() as (stdout, stderr):
+            dtb_platdata.run_steps(['struct'], dtb_file, False, output, True,
+                               [None, '', 'tools/dtoc/dtoc_test_scan_drivers.cxx'])
+
+    def testUnicodeError(self):
+        """Test running dtoc with an invalid unicode file
+
+        To be able to perform this test without adding a weird text file which
+        would produce issues when using checkpatch.pl or patman, generate the
+        file at runtime and then process it.
+        """
+        dtb_file = get_dtb_file('dtoc_test_simple.dts')
+        output = tools.GetOutputFilename('output')
+        driver_fn = '/tmp/' + next(tempfile._get_candidate_names())
+        with open(driver_fn, 'wb+') as df:
+            df.write(b'\x81')
+
+        with test_util.capture_sys_output() as (stdout, stderr):
+            dtb_platdata.run_steps(['struct'], dtb_file, False, output, True,
+                               [driver_fn])