rfemu: add max attenuation getter

this allows to query the maximum channel attenuation from within a test case

Change-Id: I35f7cb188790c59bbf2450f78c663fbc9440e406

src/osmo_gsm_tester/obj/rfemu.py

@@ -39,6 +39,11 @@ class RFemulation(log.Origin, metaclass=ABCMeta):
         """Set attenuation in dB on the configured channel"""
         pass
 
+    @abstractmethod
+    def get_max_attenuation(self):
+        """Get maximum channel attenuation"""
+        pass
+
 def get_instance_by_type(rfemu_type, rfemu_opt):
     """Allocate a RFemulation child class based on type. Opts are passed to the newly created object."""
     if rfemu_type == 'amarisoftctl':

src/osmo_gsm_tester/obj/rfemu_amarisoftctrl.py

@@ -59,5 +59,7 @@ class RFemulationAmarisoftCtrl(RFemulation):
         result = self.ws.recv()
         self.dbg('Received CTRL msg: "%s"' % result)
 
+    def get_max_attenuation(self):
+        return 200 # maximum cell_gain value in Amarisoft
 
 # vim: expandtab tabstop=4 shiftwidth=4

src/osmo_gsm_tester/obj/rfemu_minicircuits.py

@@ -64,4 +64,8 @@ class RFemulationMinicircuitsHTTP(RFemulation):
         self.dbg('Received response: "%s"' % data_str)
         if data_str != '1':
             raise log.Error('Mini-circuits attenuation device returned failure! %s' & data_str)
+
+    def get_max_attenuation(self):
+        return 95 # Maximum value of the Mini-Circuits RC4DAT-6G-95
+
 # vim: expandtab tabstop=4 shiftwidth=4