servo_updater: make more robust on resets

long-term, we need to pull this into hdctools, rather than reimplement
everything twice. Short term, this is a fine solution. It essentially
makes sure that
1. we only keep one pty/stm32uart/stm32usb object around for
communication
2. we always reset it properly when it could need a reset e.g. when the
stm32 is rebooting, or a new firmware was flashed
3. it expands the timeout for the chip to come back to 2s

the tiny_servod will eventually also land in hdctools, though for now it
just ensures that we can reset the pyusb communication without larger
issues and a larger refactor.

BUG=chromium:1152838
BRANCH=None
// Timeout before change, runs after change
TEST=sudo servo_updater --board servo_micro
// Timeout before change, runs after change
TEST=sudo servo_updater --board sweetberry
// Timeout before change, runs after change
TEST=sudo servo_updater --board servo_micro --force
// to show the serialname support. This is a fake serial, and it gets
stuck waiting
TEST=sudo servo_updater -s MICRO-S-2009020022 --board servo_micro
// to show the serialname support. This is a real serial and it proceeds
TEST=sudo servo_updater -s MICRO-S-2009020022 --board servo_micro

Change-Id: I747ca69881c13c1aadd8e90a35badecbf4e6a09e
Signed-off-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2580854
Reviewed-by: Otabek Kasimov <otabek@google.com>
Reviewed-by: Garry Wang <xianuowang@chromium.org>
(cherry picked from commit c1ff0aed409b5ddf03538448e2e4c773b97986f4)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2585855

1 files changed, 50 insertions, 0 deletions

diff --git a/extra/tigertool/ecusb/tiny_servod.py b/extra/tigertool/ecusb/tiny_servod.py
new file mode 100644
index 0000000000..aec87995a4
--- /dev/null
+++ b/extra/tigertool/ecusb/tiny_servod.py
@@ -0,0 +1,50 @@
+# Copyright 2020 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Helper class to facilitate communication to servo ec console."""
+
+from ecusb import pty_driver
+from ecusb import stm32uart
+
+
+class TinyServod(object):
+  """Helper class to wrap a pty_driver with interface."""
+
+  def __init__(self, vid, pid, interface, serialname=None, debug=False):
+    """Build the driver and interface.
+
+    Args:
+      vid: servo device vid
+      pid: servo device pid
+      interface: which usb interface the servo console is on
+      serialname: the servo device serial (if available)
+    """
+    self._vid = vid
+    self._pid = pid
+    self._interface = interface
+    self._serial = serialname
+    self._debug = debug
+    self._init()
+
+  def _init(self):
+    self.suart = stm32uart.Suart(vendor=self._vid,
+                                 product=self._pid,
+                                 interface=self._interface,
+                                 serialname=self._serial,
+                                 debuglog=self._debug)
+    self.suart.run()
+    self.pty = pty_driver.ptyDriver(self.suart, [])
+
+  def reinitialize(self):
+    """Reinitialize the connect after a reset/disconnect/etc."""
+    self.close()
+    self._init()
+
+  def close(self):
+    """Close out the connection and release resources.
+
+    Note: if another TinyServod process or servod itself needs the same device
+          it's necessary to call this to ensure the usb device is available.
+    """
+    self.suart.close()