GM: Parse distance button from steering wheel (#31762)

selfdrive/car/gm/carstate.py

@@ -26,11 +26,16 @@ class CarState(CarStateBase):
     self.cam_lka_steering_cmd_counter = 0
     self.buttons_counter = 0
 
+    self.prev_distance_button = 0
+    self.distance_button = 0
+
   def update(self, pt_cp, cam_cp, loopback_cp):
     ret = car.CarState.new_message()
 
     self.prev_cruise_buttons = self.cruise_buttons
+    self.prev_distance_button = self.distance_button
     self.cruise_buttons = pt_cp.vl["ASCMSteeringButton"]["ACCButtons"]
+    self.distance_button = pt_cp.vl["ASCMSteeringButton"]["DistanceButton"]
     self.buttons_counter = pt_cp.vl["ASCMSteeringButton"]["RollingCounter"]
     self.pscm_status = copy.copy(pt_cp.vl["PSCMStatus"])
     # This is to avoid a fault where you engage while still moving backwards after shifting to D.

selfdrive/car/gm/interface.py

@@ -208,8 +208,12 @@ class CarInterface(CarInterfaceBase):
 
     # Don't add event if transitioning from INIT, unless it's to an actual button
     if self.CS.cruise_buttons != CruiseButtons.UNPRESS or self.CS.prev_cruise_buttons != CruiseButtons.INIT:
-      ret.buttonEvents = create_button_events(self.CS.cruise_buttons, self.CS.prev_cruise_buttons, BUTTONS_DICT,
-                                              unpressed_btn=CruiseButtons.UNPRESS)
+      ret.buttonEvents = [
+        *create_button_events(self.CS.cruise_buttons, self.CS.prev_cruise_buttons, BUTTONS_DICT,
+                              unpressed_btn=CruiseButtons.UNPRESS),
+        *create_button_events(self.CS.distance_button, self.CS.prev_distance_button,
+                              {1: ButtonType.gapAdjustCruise})
+      ]
 
     # The ECM allows enabling on falling edge of set, but only rising edge of resume
     events = self.create_common_events(ret, extra_gears=[GearShifter.sport, GearShifter.low,