Introduce initial Amarisoft ENB support

* object class expects the amarisoft software to be placed in directory
  provided by env var AMARISOFT_PATH_ENB. On local runs, it will run the
  software from there. On remote runs it will copy over that directory to
  the slave.
* Configuration provided works with 6 PRBs, but probably won't work for
  other values (yet).
* ZMQ support not yet available, only UHD.

One can select the Amarisoft ENB by declaring it in resources.conf:
"""
- label: AmarisoftENB-B200
  type: amarisoftenb
  rf_dev_type: uhd
  rf_dev_args: "type=b200,serial=317B9FE,recv_frame_size=9232,send_frame_size=9232"
  remote_user: jenkins
  addr: 10.12.1.206
"""

And running:
"""
$ export AMARISOFT_PATH_ENB=/path/to/binaries
$ osmo-gsm-tester.py ... -s 4g:amarisoftenb-rftype@uhd+srsue-rftype@UHD+mod-enb-nprb@6 -t ping
"""

Change-Id: I1ddf4962ea6438ad977382ab201b724028ca46b3
diff --git a/src/osmo_gsm_tester/enb.py b/src/osmo_gsm_tester/enb.py
new file mode 100644
index 0000000..f6b7722
--- /dev/null
+++ b/src/osmo_gsm_tester/enb.py
@@ -0,0 +1,67 @@
+# osmo_gsm_tester: base classes to share code among eNodeB subclasses.
+#
+# Copyright (C) 2020 by sysmocom - s.f.m.c. GmbH
+#
+# Author: Pau Espin Pedrol <pespin@sysmocom.de>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from abc import ABCMeta, abstractmethod
+from . import log
+
+
+class eNodeB(log.Origin, metaclass=ABCMeta):
+
+##############
+# PROTECTED
+##############
+    def __init__(self, suite_run, conf, name):
+        super().__init__(log.C_RUN, '%s' % name)
+        self._conf = conf
+        self._addr = conf.get('addr', None)
+        if self._addr is None:
+            raise log.Error('addr not set')
+        self.set_name('%s_%s' % (name, self._addr))
+
+########################
+# PUBLIC - INTERNAL API
+########################
+    def cleanup(self):
+        'Nothing to do by default. Subclass can override if required.'
+        pass
+
+###################
+# PUBLIC (test API included)
+###################
+    @abstractmethod
+    def start(self, epc):
+        'Starts ENB, it will connect to "epc"'
+        pass
+
+    @abstractmethod
+    def ue_add(self, ue):
+        pass
+
+    @abstractmethod
+    def running(self):
+        pass
+
+    @abstractmethod
+    def ue_max_rate(self, downlink=True):
+        pass
+
+    def addr(self):
+        return self._addr
+
+# vim: expandtab tabstop=4 shiftwidth=4