soc: nxp: mcx/mcxn: Enable poweroff for mcxn series

This commit introduced the following changes:
1. Selected kconfig option 'HAS_POWEROFF' for NXP
   MCXN series.
2. Added power.c for NXP MCXN series, in this file,
   we currently implemented 'z_sys_poweroff()' function.
3. For the MCXN series, after waking up from the deep
   power down mode, the reset handler will be executed,
   and we need to release the I/O pads and certain peripheral
   devices to normal operating mode in 'soc_reset_hook'.

Signed-off-by: Zhaoxiang Jin <Zhaoxiang.Jin_1@nxp.com>

Author: ZhaoxiangJin

soc/nxp/mcx/mcxn/CMakeLists.txt

@@ -34,3 +34,7 @@ endif()
 zephyr_include_directories(.)
 
 set(SOC_LINKER_SCRIPT ${ZEPHYR_BASE}/include/zephyr/arch/arm/cortex_m/scripts/linker.ld CACHE INTERNAL "")
+
+if(CONFIG_POWEROFF)
+  zephyr_sources(power.c)
+endif()

soc/nxp/mcx/mcxn/Kconfig

@@ -10,6 +10,7 @@ config SOC_SERIES_MCXN
 	select CPU_CORTEX_M_HAS_SYSTICK
 	select CPU_CORTEX_M_HAS_DWT
 	select HAS_MCUX_MCX_CMC
+	select HAS_POWEROFF
 
 config SOC_MCXN947_CPU0
 	select CPU_CORTEX_M33

soc/nxp/mcx/mcxn/power.c

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2025 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/sys/poweroff.h>
+#include <zephyr/toolchain.h>
+#include "fsl_cmc.h"
+#include "fsl_spc.h"
+#include "fsl_vbat.h"
+#include "fsl_wuu.h"
+
+void z_sys_poweroff(void)
+{
+    cmc_power_domain_config_t cmc_config = {
+        .clock_mode  = kCMC_GateAllSystemClocksEnterLowPowerMode,
+        .main_domain = kCMC_DeepPowerDown,
+        .wake_domain = kCMC_DeepPowerDown,
+    };
+
+    WUU_SetInternalWakeUpModulesConfig(WUU0, 6U, kWUU_InternalModuleInterrupt);
+    SPC_SetLowPowerWakeUpDelay(SPC0, 0x637);
+
+    CMC_SetPowerModeProtection(CMC0, kCMC_AllowDeepPowerDownMode);
+    CMC_EnterLowPowerMode(CMC0, &cmc_config);
+
+    CODE_UNREACHABLE;
+}

soc/nxp/mcx/mcxn/soc.c

@@ -16,11 +16,23 @@
 #include <zephyr/device.h>
 #include <zephyr/init.h>
 #include <soc.h>
+#if defined(CONFIG_PM) || defined(CONFIG_POWEROFF)
+#include <fsl_spc.h>
+#include <fsl_cmc.h>
+#endif
 
 #ifdef CONFIG_SOC_RESET_HOOK
 
 void soc_reset_hook(void)
 {
+#if defined(CONFIG_PM) || defined(CONFIG_POWEROFF)
+	/* Release the I/O pads and certain peripherals to normal run mode state,
+	 * for in Power Down mode they will be in a latched state.
+	 */
+	if ((CMC_GetSystemResetStatus(CMC0) & kCMC_WakeUpReset) != 0UL) {
+		SPC_ClearPeriphIOIsolationFlag(SPC0);
+	}
+#endif
 	SystemInit();
 }