Support SDR extention in oem handler

Change-Id: I69f10b90e74cfc6562ad1cbadb49b5b8288a98a3

pyghmi/ipmi/command.py

@@ -604,8 +604,12 @@ class Command(object):
         # to store cached copies for given device id, product id, mfg id,
         # sdr timestamp, our data version revision, aux firmware revision,
         # and oem defined field
+        self.oem_init()
         if self._sdr is None:
-            self._sdr = sdr.SDR(self, self._sdrcachedir)
+            if hasattr(self._oem, 'init_sdr'):
+                self._sdr = self._oem.init_sdr()
+            else:
+                self._sdr = sdr.SDR(self, self._sdrcachedir)
         return self._sdr
 
     def get_event_constants(self):

pyghmi/ipmi/sdr.py

@@ -836,9 +836,12 @@ class SDR(object):
             if self.sensors[number].readable:
                 yield number
 
+    def make_sdr_entry(self, sdrbytes):
+        return SDREntry(sdrbytes, self.ipmicmd.get_event_constants(),
+                        False, self.mfg_id, self.prod_id)
+
     def add_sdr(self, sdrbytes):
-        newent = SDREntry(sdrbytes, self.ipmicmd.get_event_constants(),
-                          False, self.mfg_id, self.prod_id)
+        newent = self.make_sdr_entry(sdrbytes)
         if newent.sdrtype == TYPE_SENSOR:
             id = '{0}.{1}.{2}'.format(
                 newent.sensor_owner, newent.sensor_number, newent.sensor_lun)