kinematics: Generic Cartesian kinematics implementation (#6815)

* tests: Added a regression test for generic_cartesian kinematics

* kinematics: An intial implementation of generic_cartesian kinematics

* generic_cartesian: Refactored kinematics configuration API

* generic_cartesian: Use stepper instead of kinematic_stepper in configs

* generic_cartesian: Added SET_STEPPER_KINEMATICS command

* generic_cartesian: Fixed parsing of section names

* docs: Generic Caretsian kinematics documentation and config samples

* generic_cartesian: Implemented multi-mcu homing validation

* generic_cartesian: Fixed typos in docs, minor fixes

* generic_cartesian: Renamed `kinematics` option to `carriages`

* generic_cartesian: Moved kinematic_stepper.py file

* idex_modes: Internal refactoring of handling dual carriages

* stepper: Refactored the code to not store a reference to config object

* config: Updated example-generic-cartesian config

* generic_cartesian: Restricted SET_STEPPER_CARRIAGES and exported status

* idex_modes: Fixed handling stepper kinematics with input shaper enabled

* config: Updated configs and tests for SET_DUAL_CARRIAGE new params

* generic_cartesian: Avoid inheritance in the added classes

Signed-off-by: Dmitry Butyugin <dmbutyugin@google.com>

klippy/extras/homing.py

@@ -45,7 +45,7 @@ class StepperPosition:
 class HomingMove:
     def __init__(self, printer, endstops, toolhead=None):
         self.printer = printer
-        self.endstops = endstops
+        self.endstops = [es for es in endstops if es[0].get_steppers()]
         if toolhead is None:
             toolhead = printer.lookup_object('toolhead')
         self.toolhead = toolhead
@@ -71,7 +71,9 @@ class HomingMove:
             sname = stepper.get_name()
             kin_spos[sname] += offsets.get(sname, 0) * stepper.get_step_dist()
         thpos = self.toolhead.get_position()
-        return list(kin.calc_position(kin_spos))[:3] + thpos[3:]
+        cpos = kin.calc_position(kin_spos)
+        return [cp if cp is not None else tp
+                for cp, tp in zip(cpos, thpos[:3])] + thpos[3:]
     def homing_move(self, movepos, speed, probe_pos=False,
                     triggered=True, check_triggered=True):
         # Notify start of homing/probing move
@@ -233,6 +235,10 @@ class Homing:
                         for s in kin.get_steppers()}
             newpos = kin.calc_position(kin_spos)
             for axis in force_axes:
+                if newpos[axis] is None:
+                    raise self.printer.command_error(
+                            "Cannot determine position of toolhead on "
+                            "axis %s after homing" % "xyz"[axis])
                 homepos[axis] = newpos[axis]
             self.toolhead.set_position(homepos)