refactor(core): Use /omit-if-no-ref/ for behaviors.

* Use lesser-known DT features to skip behaviors not referenced
  in the user keymap
* Update the behaviors to skip code if no nodes found.
* Remove some empty config/data structs where unused in
  behaviors.

app/dts/behaviors/bluetooth.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		bt: behavior_bluetooth {
+		/omit-if-no-ref/ bt: behavior_bluetooth {
 			compatible = "zmk,behavior-bluetooth";
 			label = "BLUETOOTH";
 			#binding-cells = <2>;

app/dts/behaviors/ext_power.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		ext_power: behavior_ext_power {
+		/omit-if-no-ref/ ext_power: behavior_ext_power {
 			compatible = "zmk,behavior-ext-power";
 			label = "EXT_POWER_BEHAVIOR";
 			#binding-cells = <1>;

app/dts/behaviors/key_press.dtsi

@@ -7,7 +7,7 @@
 / {
 	behaviors {
 		/* DEPRECATED: `cp` will be removed in the future */
-		cp: kp: behavior_key_press {
+		/omit-if-no-ref/ cp: kp: behavior_key_press {
 			compatible = "zmk,behavior-key-press";
 			label = "KEY_PRESS";
 			#binding-cells = <1>;

app/dts/behaviors/layer_tap.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		lt: behavior_layer_tap {
+		/omit-if-no-ref/ lt: behavior_layer_tap {
 			compatible = "zmk,behavior-hold-tap";
 			label = "LAYER_TAP";
 			#binding-cells = <2>;

app/dts/behaviors/mod_tap.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		mt: behavior_mod_tap {
+		/omit-if-no-ref/ mt: behavior_mod_tap {
 			compatible = "zmk,behavior-hold-tap";
 			label = "MOD_TAP";
 			#binding-cells = <2>;

app/dts/behaviors/momentary_layer.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		mo: behavior_momentary_layer {
+		/omit-if-no-ref/ mo: behavior_momentary_layer {
 			compatible = "zmk,behavior-momentary-layer";
 			label = "MO";
 			#binding-cells = <1>;

app/dts/behaviors/none.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		none: behavior_none {
+		/omit-if-no-ref/ none: behavior_none {
 			compatible = "zmk,behavior-none";
 			label = "NONE";
 			#binding-cells = <0>;

app/dts/behaviors/outputs.dtsi

@@ -6,7 +6,7 @@
 
 / {
     behaviors {
-        out: behavior_outputs {
+        /omit-if-no-ref/ out: behavior_outputs {
             compatible = "zmk,behavior-outputs";
             label = "OUTPUTS";
             #binding-cells = <1>;

app/dts/behaviors/reset.dtsi

@@ -8,13 +8,13 @@
 
 / {
 	behaviors {
-		reset: behavior_reset {
+		/omit-if-no-ref/ reset: behavior_reset {
 			compatible = "zmk,behavior-reset";
 			label = "RESET";
 			#binding-cells = <0>;
 		};
 
-		bootloader: behavior_reset_dfu {
+		/omit-if-no-ref/ bootloader: behavior_reset_dfu {
 			compatible = "zmk,behavior-reset";
 			label = "BOOTLOADER_RESET";
 			type = <RST_UF2>;

app/dts/behaviors/rgb_underglow.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		rgb_ug: behavior_rgb_underglow {
+		/omit-if-no-ref/ rgb_ug: behavior_rgb_underglow {
 			compatible = "zmk,behavior-rgb-underglow";
 			label = "RGB_UNDERGLOW";
 			#binding-cells = <2>;

app/dts/behaviors/sensor_rotate_key_press.dtsi

@@ -7,7 +7,7 @@
 / {
 	behaviors {
 		/* DEPRECATED: `inc_dec_cp` will be removed in the future */
-		inc_dec_cp: inc_dec_kp: behavior_sensor_rotate_key_press {
+		/omit-if-no-ref/ inc_dec_cp: inc_dec_kp: behavior_sensor_rotate_key_press {
 			compatible = "zmk,behavior-sensor-rotate-key-press";
 			label = "ENC_KEY_PRESS";
 			#sensor-binding-cells = <2>;

app/dts/behaviors/sticky_key.dtsi

@@ -6,14 +6,14 @@
 
 / {
 	behaviors {
-		sk: behavior_sticky_key {
+		/omit-if-no-ref/ sk: behavior_sticky_key {
 			compatible = "zmk,behavior-sticky-key";
 			label = "STICKY_KEY";
 			#binding-cells = <1>;
 			release-after-ms = <1000>;
 			bindings = <&kp>;
 		};
-		sl: behavior_sticky_layer {
+		/omit-if-no-ref/ sl: behavior_sticky_layer {
 			compatible = "zmk,behavior-sticky-key";
 			label = "STICKY_LAYER";
 			#binding-cells = <1>;

app/dts/behaviors/to_layer.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		to: behavior_to_layer {
+		/omit-if-no-ref/ to: behavior_to_layer {
 			compatible = "zmk,behavior-to-layer";
 			label = "TO_LAYER";
 			#binding-cells = <1>;

app/dts/behaviors/toggle_layer.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		tog: behavior_toggle_layer {
+		/omit-if-no-ref/ tog: behavior_toggle_layer {
 			compatible = "zmk,behavior-toggle-layer";
 			label = "TOGGLE_LAYER";
 			#binding-cells = <1>;

app/dts/behaviors/transparent.dtsi

@@ -6,7 +6,7 @@
 
 / {
 	behaviors {
-		trans: behavior_transparent {
+		/omit-if-no-ref/ trans: behavior_transparent {
 			compatible = "zmk,behavior-transparent";
 			label = "TRANS";
 			#binding-cells = <0>;

app/src/behaviors/behavior_bt.c

@@ -17,6 +17,8 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
 #include <zmk/ble.h>
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
                                      struct zmk_behavior_binding_event event) {
     switch (binding->param1) {
@@ -49,3 +51,5 @@ static const struct behavior_driver_api behavior_bt_driver_api = {
 
 DEVICE_AND_API_INIT(behavior_bt, DT_INST_LABEL(0), behavior_bt_init, NULL, NULL, APPLICATION,
                     CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_bt_driver_api);
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_ext_power.c

@@ -16,6 +16,8 @@
 #include <logging/log.h>
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
                                      struct zmk_behavior_binding_event event) {
     const struct device *ext_power = device_get_binding("EXT_POWER");
@@ -55,3 +57,5 @@ static const struct behavior_driver_api behavior_ext_power_driver_api = {
 
 DEVICE_AND_API_INIT(behavior_ext_power, DT_INST_LABEL(0), behavior_ext_power_init, NULL, NULL,
                     APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY, &behavior_ext_power_driver_api);
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_hold_tap.c

@@ -22,7 +22,7 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
-#if DT_NODE_EXISTS(DT_DRV_INST(0))
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
 
 #define ZMK_BHV_HOLD_TAP_MAX_HELD 10
 #define ZMK_BHV_HOLD_TAP_MAX_CAPTURED_EVENTS 40
@@ -538,4 +538,4 @@ static struct behavior_hold_tap_data behavior_hold_tap_data;
 
 DT_INST_FOREACH_STATUS_OKAY(KP_INST)
 
-#endif
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_none.c

@@ -15,8 +15,7 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
-struct behavior_none_config {};
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
-struct behavior_none_data {};
 
 static int behavior_none_init(const struct device *dev) { return 0; };
 
@@ -35,10 +34,7 @@ static const struct behavior_driver_api behavior_none_driver_api = {
     .binding_released = on_keymap_binding_released,
 };
 
-static const struct behavior_none_config behavior_none_config = {};
+DEVICE_AND_API_INIT(behavior_none, DT_INST_LABEL(0), behavior_none_init, NULL, NULL, APPLICATION,
+                    CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_none_driver_api);
 
-static struct behavior_none_data behavior_none_data;
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */
-
-DEVICE_AND_API_INIT(behavior_none, DT_INST_LABEL(0), behavior_none_init, &behavior_none_data,
-                    &behavior_none_config, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
-                    &behavior_none_driver_api);

app/src/behaviors/behavior_outputs.c

@@ -18,6 +18,8 @@
 #include <logging/log.h>
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
                                      struct zmk_behavior_binding_event event) {
     switch (binding->param1) {
@@ -42,3 +44,5 @@ static const struct behavior_driver_api behavior_outputs_driver_api = {
 
 DEVICE_AND_API_INIT(behavior_out, DT_INST_LABEL(0), behavior_out_init, NULL, NULL, APPLICATION,
                     CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_outputs_driver_api);
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_reset.c

@@ -15,6 +15,7 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
 struct behavior_reset_config {
     int type;
 };
@@ -45,3 +46,5 @@ static const struct behavior_driver_api behavior_reset_driver_api = {
                         CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_reset_driver_api);
 
 DT_INST_FOREACH_STATUS_OKAY(RST_INST)
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_rgb_underglow.c

@@ -16,6 +16,8 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 static int behavior_rgb_underglow_init(const struct device *dev) { return 0; }
 
 static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
@@ -64,3 +66,5 @@ static const struct behavior_driver_api behavior_rgb_underglow_driver_api = {
 DEVICE_AND_API_INIT(behavior_rgb_underglow, DT_INST_LABEL(0), behavior_rgb_underglow_init, NULL,
                     NULL, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
                     &behavior_rgb_underglow_driver_api);
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_sensor_rotate_key_press.c

@@ -16,6 +16,8 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 static int behavior_sensor_rotate_key_press_init(const struct device *dev) { return 0; };
 
 static int on_sensor_binding_triggered(struct zmk_behavior_binding *binding,
@@ -63,3 +65,5 @@ static const struct behavior_driver_api behavior_sensor_rotate_key_press_driver_
                         &behavior_sensor_rotate_key_press_driver_api);
 
 DT_INST_FOREACH_STATUS_OKAY(KP_INST)
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_to_layer.c

@@ -15,6 +15,8 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 static int behavior_to_init(const struct device *dev) { return 0; };
 
 static int to_keymap_binding_pressed(struct zmk_behavior_binding *binding,
@@ -37,3 +39,5 @@ static const struct behavior_driver_api behavior_to_driver_api = {
 
 DEVICE_AND_API_INIT(behavior_to, DT_INST_LABEL(0), behavior_to_init, NULL, NULL, APPLICATION,
                     CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_to_driver_api);
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_toggle_layer.c

@@ -15,6 +15,8 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
+
 struct behavior_tog_config {};
 struct behavior_tog_data {};
 
@@ -44,3 +46,5 @@ static struct behavior_tog_data behavior_tog_data;
 DEVICE_AND_API_INIT(behavior_tog, DT_INST_LABEL(0), behavior_tog_init, &behavior_tog_data,
                     &behavior_tog_config, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
                     &behavior_tog_driver_api);
+
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

app/src/behaviors/behavior_transparent.c

@@ -15,8 +15,7 @@
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
-struct behavior_transparent_config {};
+#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
-struct behavior_transparent_data {};
 
 static int behavior_transparent_init(const struct device *dev) { return 0; };
 
@@ -35,10 +34,8 @@ static const struct behavior_driver_api behavior_transparent_driver_api = {
     .binding_released = on_keymap_binding_released,
 };
 
-static const struct behavior_transparent_config behavior_transparent_config = {};
+DEVICE_AND_API_INIT(behavior_transparent, DT_INST_LABEL(0), behavior_transparent_init, NULL, NULL,
+                    APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,
+                    &behavior_transparent_driver_api);
 
-static struct behavior_transparent_data behavior_transparent_data;
+#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */
-
-DEVICE_AND_API_INIT(behavior_transparent, DT_INST_LABEL(0), behavior_transparent_init,
-                    &behavior_transparent_data, &behavior_transparent_config, APPLICATION,
-                    CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_transparent_driver_api);