selftests/hid: tablets: add variants of states with buttons

Turns out that there are transitions that are unlikely to happen:
for example, having both the tip switch and a button being changed
at the same time (in the same report) would require either a very talented
and precise user or a very bad hardware with a very low sampling rate.

So instead of manually building the button test by hand and forgetting
about some cases, let's reuse the state machine and transitions we have.

This patch only adds the states and the valid transitions. The actual
tests will be replaced later.

Reviewed-by: Peter Hutterer <[e-mail]>
Acked-by: Jiri Kosina <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Benjamin Tissoires <[e-mail]>

tools/testing/selftests/hid/tests/test_tablet.py

···
     RUBBER = libevdev.EV_KEY.BTN_TOOL_RUBBER
 
 
+class BtnPressed(Enum):
+    """Represents whether a button is pressed on the stylus"""
+
+    PRIMARY_PRESSED = libevdev.EV_KEY.BTN_STYLUS
+    SECONDARY_PRESSED = libevdev.EV_KEY.BTN_STYLUS2
+
+
 class PenState(Enum):
     """Pen states according to Microsoft reference:
     https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/windows-pen-states
+
+    We extend it with the various buttons when we need to check them.
     """
 
-    PEN_IS_OUT_OF_RANGE = BtnTouch.UP, None
-    PEN_IS_IN_RANGE = BtnTouch.UP, ToolType.PEN
-    PEN_IS_IN_CONTACT = BtnTouch.DOWN, ToolType.PEN
-    PEN_IS_IN_RANGE_WITH_ERASING_INTENT = BtnTouch.UP, ToolType.RUBBER
-    PEN_IS_ERASING = BtnTouch.DOWN, ToolType.RUBBER
+    PEN_IS_OUT_OF_RANGE = BtnTouch.UP, None, None
+    PEN_IS_IN_RANGE = BtnTouch.UP, ToolType.PEN, None
+    PEN_IS_IN_RANGE_WITH_BUTTON = BtnTouch.UP, ToolType.PEN, BtnPressed.PRIMARY_PRESSED
+    PEN_IS_IN_RANGE_WITH_SECOND_BUTTON = (
+        BtnTouch.UP,
+        ToolType.PEN,
+        BtnPressed.SECONDARY_PRESSED,
+    )
+    PEN_IS_IN_CONTACT = BtnTouch.DOWN, ToolType.PEN, None
+    PEN_IS_IN_CONTACT_WITH_BUTTON = (
+        BtnTouch.DOWN,
+        ToolType.PEN,
+        BtnPressed.PRIMARY_PRESSED,
+    )
+    PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON = (
+        BtnTouch.DOWN,
+        ToolType.PEN,
+        BtnPressed.SECONDARY_PRESSED,
+    )
+    PEN_IS_IN_RANGE_WITH_ERASING_INTENT = BtnTouch.UP, ToolType.RUBBER, None
+    PEN_IS_IN_RANGE_WITH_ERASING_INTENT_WITH_BUTTON = (
+        BtnTouch.UP,
+        ToolType.RUBBER,
+        BtnPressed.PRIMARY_PRESSED,
+    )
+    PEN_IS_IN_RANGE_WITH_ERASING_INTENT_WITH_SECOND_BUTTON = (
+        BtnTouch.UP,
+        ToolType.RUBBER,
+        BtnPressed.SECONDARY_PRESSED,
+    )
+    PEN_IS_ERASING = BtnTouch.DOWN, ToolType.RUBBER, None
+    PEN_IS_ERASING_WITH_BUTTON = (
+        BtnTouch.DOWN,
+        ToolType.RUBBER,
+        BtnPressed.PRIMARY_PRESSED,
+    )
+    PEN_IS_ERASING_WITH_SECOND_BUTTON = (
+        BtnTouch.DOWN,
+        ToolType.RUBBER,
+        BtnPressed.SECONDARY_PRESSED,
+    )
 
-    def __init__(self, touch: BtnTouch, tool: Optional[ToolType]):
+    def __init__(self, touch: BtnTouch, tool: Optional[ToolType], button: Optional[BtnPressed]):
         self.touch = touch
         self.tool = tool
+        self.button = button
 
     @classmethod
     def from_evdev(cls, evdev) -> "PenState":
         touch = BtnTouch(evdev.value[libevdev.EV_KEY.BTN_TOUCH])
         tool = None
+        button = None
         if (
             evdev.value[libevdev.EV_KEY.BTN_TOOL_RUBBER]
             and not evdev.value[libevdev.EV_KEY.BTN_TOOL_PEN]
···
         ):
             raise ValueError("2 tools are not allowed")
 
-        return cls((touch, tool))
+        # we take only the highest button in account
+        for b in [libevdev.EV_KEY.BTN_STYLUS, libevdev.EV_KEY.BTN_STYLUS2]:
+            if bool(evdev.value[b]):
+                button = b
+
+        # the kernel tends to insert an EV_SYN once removing the tool, so
+        # the button will be released after
+        if tool is None:
+            button = None
+
+        return cls((touch, tool, button))
 
     def apply(self, events) -> "PenState":
         if libevdev.EV_SYN.SYN_REPORT in events:
···
         touch_found = False
         tool = self.tool
         tool_found = False
+        button = self.button
+        button_found = False
 
         for ev in events:
             if ev == libevdev.InputEvent(libevdev.EV_KEY.BTN_TOUCH):
···
                 if tool_found:
                     raise ValueError(f"duplicated BTN_TOOL_* in {events}")
                 tool_found = True
-                if ev.value:
-                    tool = ToolType(ev.code)
-                else:
-                    tool = None
+                tool = ToolType(ev.code) if ev.value else None
+            elif ev in (
+                libevdev.InputEvent(libevdev.EV_KEY.BTN_STYLUS),
+                libevdev.InputEvent(libevdev.EV_KEY.BTN_STYLUS2),
+            ):
+                if button_found:
+                    raise ValueError(f"duplicated BTN_STYLUS* in {events}")
+                button_found = True
+                button = ev.code if ev.value else None
 
-        new_state = PenState((touch, tool))
+        # the kernel tends to insert an EV_SYN once removing the tool, so
+        # the button will be released after
+        if tool is None:
+            button = None
+
+        new_state = PenState((touch, tool, button))
         assert (
             new_state in self.valid_transitions()
         ), f"moving from {self} to {new_state} is forbidden"
···
             return (
                 PenState.PEN_IS_OUT_OF_RANGE,
                 PenState.PEN_IS_IN_RANGE,
+                PenState.PEN_IS_IN_RANGE_WITH_BUTTON,
+                PenState.PEN_IS_IN_RANGE_WITH_SECOND_BUTTON,
                 PenState.PEN_IS_IN_RANGE_WITH_ERASING_INTENT,
                 PenState.PEN_IS_IN_CONTACT,
+                PenState.PEN_IS_IN_CONTACT_WITH_BUTTON,
+                PenState.PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON,
                 PenState.PEN_IS_ERASING,
             )
 
         if self == PenState.PEN_IS_IN_RANGE:
             return (
                 PenState.PEN_IS_IN_RANGE,
+                PenState.PEN_IS_IN_RANGE_WITH_BUTTON,
+                PenState.PEN_IS_IN_RANGE_WITH_SECOND_BUTTON,
                 PenState.PEN_IS_OUT_OF_RANGE,
                 PenState.PEN_IS_IN_CONTACT,
             )
···
         if self == PenState.PEN_IS_IN_CONTACT:
             return (
                 PenState.PEN_IS_IN_CONTACT,
+                PenState.PEN_IS_IN_CONTACT_WITH_BUTTON,
+                PenState.PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON,
                 PenState.PEN_IS_IN_RANGE,
                 PenState.PEN_IS_OUT_OF_RANGE,
             )
···
             return (
                 PenState.PEN_IS_ERASING,
                 PenState.PEN_IS_IN_RANGE_WITH_ERASING_INTENT,
+                PenState.PEN_IS_OUT_OF_RANGE,
+            )
+
+        if self == PenState.PEN_IS_IN_RANGE_WITH_BUTTON:
+            return (
+                PenState.PEN_IS_IN_RANGE_WITH_BUTTON,
+                PenState.PEN_IS_IN_RANGE,
+                PenState.PEN_IS_OUT_OF_RANGE,
+                PenState.PEN_IS_IN_CONTACT_WITH_BUTTON,
+            )
+
+        if self == PenState.PEN_IS_IN_CONTACT_WITH_BUTTON:
+            return (
+                PenState.PEN_IS_IN_CONTACT_WITH_BUTTON,
+                PenState.PEN_IS_IN_CONTACT,
+                PenState.PEN_IS_IN_RANGE_WITH_BUTTON,
+                PenState.PEN_IS_OUT_OF_RANGE,
+            )
+
+        if self == PenState.PEN_IS_IN_RANGE_WITH_SECOND_BUTTON:
+            return (
+                PenState.PEN_IS_IN_RANGE_WITH_SECOND_BUTTON,
+                PenState.PEN_IS_IN_RANGE,
+                PenState.PEN_IS_OUT_OF_RANGE,
+                PenState.PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON,
+            )
+
+        if self == PenState.PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON:
+            return (
+                PenState.PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON,
+                PenState.PEN_IS_IN_CONTACT,
+                PenState.PEN_IS_IN_RANGE_WITH_SECOND_BUTTON,
                 PenState.PEN_IS_OUT_OF_RANGE,
             )
 
···
             pen.xtilt = 0
             pen.ytilt = 0
             pen.twist = 0
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = False
         elif state == PenState.PEN_IS_IN_RANGE:
             pen.tipswitch = False
             pen.inrange = True
             pen.invert = False
             pen.eraser = False
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = False
         elif state == PenState.PEN_IS_IN_CONTACT:
             pen.tipswitch = True
             pen.inrange = True
             pen.invert = False
             pen.eraser = False
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = False
+        elif state == PenState.PEN_IS_IN_RANGE_WITH_BUTTON:
+            pen.tipswitch = False
+            pen.inrange = True
+            pen.invert = False
+            pen.eraser = False
+            pen.barrelswitch = True
+            pen.secondarybarrelswitch = False
+        elif state == PenState.PEN_IS_IN_CONTACT_WITH_BUTTON:
+            pen.tipswitch = True
+            pen.inrange = True
+            pen.invert = False
+            pen.eraser = False
+            pen.barrelswitch = True
+            pen.secondarybarrelswitch = False
+        elif state == PenState.PEN_IS_IN_RANGE_WITH_SECOND_BUTTON:
+            pen.tipswitch = False
+            pen.inrange = True
+            pen.invert = False
+            pen.eraser = False
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = True
+        elif state == PenState.PEN_IS_IN_CONTACT_WITH_SECOND_BUTTON:
+            pen.tipswitch = True
+            pen.inrange = True
+            pen.invert = False
+            pen.eraser = False
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = True
         elif state == PenState.PEN_IS_IN_RANGE_WITH_ERASING_INTENT:
             pen.tipswitch = False
             pen.inrange = True
             pen.invert = True
             pen.eraser = False
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = False
         elif state == PenState.PEN_IS_ERASING:
             pen.tipswitch = False
             pen.inrange = True
             pen.invert = False
             pen.eraser = True
+            pen.barrelswitch = False
+            pen.secondarybarrelswitch = False
 
         pen.current_state = state