Add axis homing function and AXIS state

Firmware/MotorControl/controller.cpp

@@ -51,6 +51,25 @@ void Controller::start_anticogging_calibration() {
     }
 }
 
+// Slowly drive in the negative direction at homing_speed until the min endstop is pressed
+// When pressed, set the linear count to the offset (default 0), and then
+bool Controller::home_axis() {
+    if (axis_->config_.min_endstop.enabled) {
+        set_vel_setpoint(-config_.homing_speed, 0.0f);
+    } else {
+        return false;
+    }
+
+    axis_->run_control_loop([&](){
+        if(axis_->min_endstop_state_){
+            axis_->encoder_.set_linear_count(axis_->config_.min_endstop.offset);
+            set_pos_setpoint(0.0f, 0.0f, 0.0f);
+        }
+        return !axis_->min_endstop_state_;
+    });
+    return true;
+}
+
 /*
  * This anti-cogging implementation iterates through each encoder position,
  * waits for zero velocity & position error,