evdev: abstract the get_switch_state method

Shove it into the generic dispatch interface so we don't entangle evdev and
fallback.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/evdev-mt-touchpad.c

@@ -2261,6 +2261,7 @@ static struct evdev_dispatch_interface tp_interface = {
 	.device_resumed = tp_interface_device_added,   /* treat as add */
 	.post_added = NULL,
 	.toggle_touch = tp_interface_toggle_touch,
+	.get_switch_state = NULL,
 };
 
 static void

src/evdev-tablet-pad.c

@@ -514,6 +514,7 @@ static struct evdev_dispatch_interface pad_interface = {
 	.device_resumed = NULL,
 	.post_added = NULL,
 	.toggle_touch = NULL,
+	.get_switch_state = NULL,
 };
 
 static void

src/evdev-tablet.c

@@ -1882,6 +1882,7 @@ static struct evdev_dispatch_interface tablet_interface = {
 	.device_resumed = NULL,
 	.post_added = tablet_check_initial_proximity,
 	.toggle_touch = NULL,
+	.get_switch_state = NULL,
 };
 
 static void

src/evdev.c

@@ -189,7 +189,18 @@ enum libinput_switch_state
 evdev_device_switch_get_state(struct evdev_device *device,
 			      enum libinput_switch sw)
 {
-	struct fallback_dispatch *dispatch = fallback_dispatch(device->dispatch);
+	struct evdev_dispatch *dispatch = device->dispatch;
+
+	assert(dispatch->interface->get_switch_state);
+
+	return dispatch->interface->get_switch_state(dispatch, sw);
+}
+
+static enum libinput_switch_state
+fallback_get_switch_state(struct evdev_dispatch *evdev_dispatch,
+			  enum libinput_switch sw)
+{
+	struct fallback_dispatch *dispatch = fallback_dispatch(evdev_dispatch);
 
 	switch (sw) {
 	case LIBINPUT_SWITCH_TABLET_MODE:
@@ -1774,6 +1785,7 @@ struct evdev_dispatch_interface fallback_interface = {
 	.device_resumed = fallback_interface_device_added,   /* treat as add */
 	.post_added = fallback_sync_initial_state,
 	.toggle_touch = fallback_toggle_touch,
+	.get_switch_state = fallback_get_switch_state,
 };
 
 static uint32_t

src/evdev.h

@@ -313,6 +313,11 @@ struct evdev_dispatch_interface {
 	void (*toggle_touch)(struct evdev_dispatch *dispatch,
 			     struct evdev_device *device,
 			     bool enable);
+
+	/* Return the state of the given switch */
+	enum libinput_switch_state
+		(*get_switch_state)(struct evdev_dispatch *dispatch,
+				    enum libinput_switch which);
 };
 
 enum evdev_dispatch_type {