[nrf fromtree] tests: drivers: comparator: Enable nxp cmp test

Enable nxp cmp test.

Signed-off-by: Zhaoxiang Jin <[email protected]>
(cherry picked from commit 78b4fed)

Author: ZhaoxiangJin

tests/drivers/build_all/comparator/nxp_cmp/frdm_mcxc242.dts

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2025 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&cmp {
+	positive-mux-input = "IN0"; /* PTC6 */
+	negative-mux-input = "IN7"; /* DAC */
+	dac-vref-source = "VIN2";
+	dac-value = <31>;
+	filter-count = <0x3>;
+	filter-period = <0xF>;
+	hysteresis-mode = "LEVEL2";
+	enable-high-speed-mode;
+	invert-output;
+	enable-pin-out;
+};

tests/drivers/build_all/comparator/testcase.yaml

@@ -119,3 +119,8 @@ tests:
       - DTC_OVERLAY_FILE="mcux_acmp/mke15z7_mux_mux.dts"
     platform_allow:
       - frdm_ke15z
+  drivers.build_all.comparator.nxp_cmp.frdm_mcxc242:
+    extra_args:
+      - DTC_OVERLAY_FILE="nxp_cmp/frdm_mcxc242.dts"
+    platform_allow:
+      - frdm_mcxc242

tests/drivers/comparator/gpio_loopback/boards/frdm_mcxc242.overlay

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2025 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/dt-bindings/gpio/gpio.h>
+
+/ {
+	aliases {
+		test-comp = &cmp;
+	};
+
+	zephyr,user {
+		/* PTC4 output connect to PTC6. */
+		test-gpios = <&gpioc 4 GPIO_ACTIVE_HIGH>;
+	};
+};
+
+&cmp {
+	positive-mux-input = "IN0"; /* PTC6, FRDM-MCXC242 J2-8 */
+	negative-mux-input = "IN7"; /* DAC output => 1.65V */
+	dac-vref-source = "VIN2";
+	dac-value = <31>;
+};