servo_updater: introduce channels

This change introduces the ability to pull an update from a specific
channel (i.e. a specific file). See the bug for details on this project,
but basically the `servo-firmware` package now bundles multiple firmware
in the system, all of which are tagged to belong to a 'channel'. The
name of those files is then [board_name].[channel].bin. The updater then
now supports the notion of requesting a specific channel to update, if
the default (stable) is not desired.

Like the previous CL it also leverages choices for argparse to ensure no
unknown channels are requested.

BRANCH=None
BUG=b:179310743

TEST=servo_updater --help | grep channel
-c {alpha,dev,prev,stable}, --channel {alpha,dev,prev,stable}

TEST=sudo servo_updater --board servo_micro -c alpha
Current servo_micro version is   servo_micro_v2.4.35-f1113c92b
Available servo_micro version is servo_micro_v2.4.35-f1113c92b
No version update needed

Cq-Depend: chromium:2674405
Change-Id: I88c301cc4ff0ac246cbfda6498c27a1fd23f722f
Signed-off-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2661019
Reviewed-by: Brian Nemec <bnemec@chromium.org>

1 files changed, 23 insertions, 3 deletions

diff --git a/extra/usb_updater/servo_updater.py b/extra/usb_updater/servo_updater.py
index a9638c194f..a528caf9e6 100755
--- a/extra/usb_updater/servo_updater.py
+++ b/extra/usb_updater/servo_updater.py
@@ -37,6 +37,22 @@ DEFAULT_BOARD = BOARD_SERVO_V4
 BOARDS = [BOARD_C2D2, BOARD_SERVO_MICRO, BOARD_SERVO_V4, BOARD_SERVO_V4P1,
           BOARD_SWEETBERRY]
 
+# Servo firmware bundles four channels of firmware. We need to make sure the
+# user does not request a non-existing channel, so keep the lists around to
+# guard on command-line usage.
+
+DEFAULT_CHANNEL = STABLE_CHANNEL = 'stable'
+
+PREV_CHANNEL = 'prev'
+
+# The ordering here matters. From left to right it's the channel that the user
+# is most likely to be running. This is used to inform and warn the user if
+# there are issues. e.g. if the all channels are the same, we want to let the
+# user know they are running the 'stable' version before letting them know they
+# are running 'dev' or even 'alpah' which (while true) might cause confusion.
+
+CHANNELS = [DEFAULT_CHANNEL, PREV_CHANNEL, 'dev', 'alpha']
+
 DEFAULT_BASE_PATH = '/usr/'
 TEST_IMAGE_BASE_PATH = '/usr/local/'
 
@@ -211,7 +227,7 @@ def do_updater_version(tinys):
   raise ServoUpdaterException(
       "Can't determine updater target from vers: [%s]" % vers)
 
-def findfiles(cname, fname):
+def findfiles(cname, fname, channel=DEFAULT_CHANNEL):
   """Select config and firmware binary files.
 
   This checks default file names and paths.
@@ -221,6 +237,7 @@ def findfiles(cname, fname):
   Args:
     cname: board name, or config name. eg. "servo_v4" or "servo_v4.json"
     fname: firmware binary name. Can be None to try default.
+    channel: the channel requested for servo firmware. See |CHANNELS| above.
   Returns:
     cname, fname: validated filenames selected from the path.
   """
@@ -255,7 +272,7 @@ def findfiles(cname, fname):
       data = json.load(data_file)
     boardname = data['board']
 
-    binary_file = boardname + ".bin"
+    binary_file = '%s.%s.bin' % (boardname, channel)
     newname = os.path.join(firmware_path, binary_file)
     if os.path.isfile(newname):
       fname = newname
@@ -300,6 +317,9 @@ def main():
   parser.add_argument('-b', '--board', type=str,
                       help="Board configuration json file",
                       default=DEFAULT_BOARD, choices=BOARDS)
+  parser.add_argument('-c', '--channel', type=str,
+                      help="Firmware channel to use",
+                      default=DEFAULT_CHANNEL, choices=CHANNELS)
   parser.add_argument('-f', '--file', type=str,
                       help="Complete ec.bin file", default=None)
   parser.add_argument('--force', action="store_true",
@@ -311,7 +331,7 @@ def main():
 
   args = parser.parse_args()
 
-  brdfile, binfile = findfiles(args.board, args.file)
+  brdfile, binfile = findfiles(args.board, args.file, args.channel)
 
   serialno = args.serialno