GM: go passive if detected ASCM or LKA camera (commaai#350)

Since fingerprint is powertrain CAN only, camera still present
on object bus is not an issue.

selfdrive/car/gm/carcontroller.py

@@ -55,7 +55,7 @@ def actuator_hystereses(final_pedal, pedal_steady):
 
 
 class CarController(object):
-  def __init__(self, canbus, car_fingerprint):
+  def __init__(self, canbus, car_fingerprint, allow_controls):
     self.pedal_steady = 0.
     self.start_time = sec_since_boot()
     self.chime = 0
@@ -64,6 +64,7 @@ def __init__(self, canbus, car_fingerprint):
     self.steer_idx = 0
     self.apply_steer_last = 0
     self.car_fingerprint = car_fingerprint
+    self.allow_controls = allow_controls
 
     # Setup detection helper. Routes commands to
     # an appropriate CAN bus number.
@@ -77,6 +78,10 @@ def update(self, sendcan, enabled, CS, frame, actuators, \
              hud_v_cruise, hud_show_lanes, hud_show_car, chime, chime_cnt):
     """ Controls thread """
 
+    # Sanity check.
+    if not self.allow_controls:
+      return
+
     P = self.params
 
     # Send CAN commands.

selfdrive/car/gm/interface.py

@@ -21,19 +21,17 @@ class CM:
   LOW_CHIME = 0x86
   HIGH_CHIME = 0x87
 
-# GM cars have 4 CAN buses, which creates many ways
-# of how the car can be connected to.
-# This ia a helper class for the interface to be setup-agnostic.
-# Supports single Panda setup (connected to OBDII port),
-# and a CAN forwarding setup (connected to camera module connector).
-
 class CanBus(object):
   def __init__(self):
     self.powertrain = 0
     self.obstacle = 1
     self.chassis = 2
     self.sw_gmlan = 3
 
+# 384 = "ASCMLKASteeringCmd"
+# 715 = "ASCMGasRegenCmd"
+CONTROL_MSGS = [384, 715]
+
 class CarInterface(object):
   def __init__(self, CP, sendcan=None):
     self.CP = CP
@@ -54,7 +52,7 @@ def __init__(self, CP, sendcan=None):
     # sending if read only is False
     if sendcan is not None:
       self.sendcan = sendcan
-      self.CC = CarController(canbus, CP.carFingerprint)
+      self.CC = CarController(canbus, CP.carFingerprint, CP.enableCamera)
 
   @staticmethod
   def compute_gb(accel, speed):
@@ -73,8 +71,11 @@ def get_params(candidate, fingerprint):
 
     ret.enableCruise = False
 
-    # TODO: gate this on detection
-    ret.enableCamera = True
+    # Presence of a camera on the object bus is ok.
+    # Have to go passive if ASCM is online (ACC-enabled cars),
+    # or camera is on powertrain bus (LKA cars without ACC).
+    ret.enableCamera = not any(x for x in CONTROL_MSGS if x in fingerprint)
+
     std_cargo = 136
 
     if candidate == CAR.VOLT: