GM: implement allow throttle/brakes (commaai#1185)

implement allow gnb for GM

opendbc/car/gm/carcontroller.py

@@ -94,9 +94,12 @@ def update(self, CC, CS, now_nanos):
           self.apply_brake = int(round(interp(actuators.accel, self.params.BRAKE_LOOKUP_BP, self.params.BRAKE_LOOKUP_V)))
           # Don't allow any gas above inactive regen while stopping
           # FIXME: brakes aren't applied immediately when enabling at a stop
-          if stopping:
+          if stopping or not actuators.allowThrottle:
             self.apply_gas = self.params.INACTIVE_REGEN
 
+          if not actuators.allowBrake:
+            self.apply_brake = 0
+
         idx = (self.frame // 4) % 4
 
         at_full_stop = CC.longActive and CS.out.standstill

opendbc/car/structs.py

@@ -220,6 +220,9 @@ class Actuators:
     steerOutputCan: float = auto_field()
     steeringAngleDeg: float = auto_field()
 
+    allowBrake: bool = auto_field()
+    allowThrottle: bool = auto_field()
+
     curvature: float = auto_field()
 
     speed: float = auto_field()  # m/s