tools: Pad final chunks with 0xff if necessary.

[gps-watch.git] / tools / update-firmware

diff --git a/tools/update-firmware b/tools/update-firmware
index 32381dc47393ac39b32d4819d5f0ddbb54214485..cd711241ab3858d6e62cb366b1d376549ae48f47 100755 (executable)
--- a/tools/update-firmware
+++ b/tools/update-firmware
@@ -94,6 +94,12 @@ class ChecksumMismatch(BootloaderError):
 
         super(ChecksumMismatch, self).__init__(msg)
 
+class PermissionDenied(BootloaderError):
+    def __init__(self, command):
+        msg = 'Target reported permission denied for command {}'.format(command)
+
+        super(PermissionDenied, self).__init__(msg)
+
 class Command:
     def __init__(self, num, name):
         self._num = num
@@ -162,6 +168,13 @@ class Application:
                 sys.stderr.write('File too large.\n')
                 return 3
 
+            # The bootloader only accepts chunks whose size is word-aligned:
+            num_extra = len(chunks[-1]) & 3
+
+            if num_extra != 0:
+                num_pad = 4 - extra
+                chunks[-1] += b'\xff' * num_pad
+
         # Defaulting to zero seems too dangerous:
         if self._offset is None:
             sector0 = None
@@ -179,15 +192,19 @@ class Application:
             for i in range(len(chunks)):
                 sector = sector0 + i
 
-                self._erase(sector)
+                # The bootloader will refuse to erase the second sector
+                # as it contains the precious flash configuration field.
+                if sector != 1:
+                    self._erase(sector)
 
             # Write first sector last, to prevent the bootloader from
             # jumping to partially programmed code.
             for i, chunk in reversed(list(enumerate(chunks))):
                 sector = sector0 + i
 
-                self._load_chunk(chunk)
-                self._program(sector)
+                if sector != 1:
+                    self._load_chunk(chunk)
+                    self._program(sector)
 
         num_verify_errors = 0
 
@@ -295,6 +312,8 @@ class Application:
             raise InvalidArgument(self._last_command)
         elif e == 3:
             raise ChecksumMismatch(self._last_command)
+        elif e == 4:
+            raise PermissionDenied(self._last_command)
         else:
             msg = 'Target reported some other error for {}'.format(self._last_command)