[nrf fromlist] modules: hal_nordic: Allow app mem from net core in serialized 802.15.4

Currently, the serialization module for 802.15.4 enabled
the network core without giving it access to application
core memory in trusted execution mode. This commit
grands this access.

Upstream PR: zephyrproject-rtos/zephyr#79316

Signed-off-by: Dominik Kilian <[email protected]>

Author: doki-nordic

modules/hal_nordic/nrf_802154/serialization/platform/nrf_802154_spinel_backend_ipc.c

@@ -9,6 +9,11 @@
 #include <zephyr/device.h>
 #include <zephyr/logging/log.h>
 
+#if defined(CONFIG_SOC_NRF5340_CPUAPP)
+#include <nrf53_cpunet_mgmt.h>
+#include <hal/nrf_spu.h>
+#endif
+
 #include "nrf_802154.h"
 #include "nrf_802154_spinel_backend_callouts.h"
 #include "nrf_802154_serialization_error.h"
@@ -55,6 +60,14 @@ nrf_802154_ser_err_t nrf_802154_backend_init(void)
 	int err;
 
 #if defined(CONFIG_SOC_NRF5340_CPUAPP)
+
+#if !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE)
+	/* Retain nRF5340 Network MCU in Secure domain (bus
+	 * accesses by Network MCU will have Secure attribute set).
+	 */
+	nrf_spu_extdomain_set((NRF_SPU_Type *)DT_REG_ADDR(DT_NODELABEL(spu)), 0, true, false);
+#endif /* !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE) */
+
 	nrf53_cpunet_enable(true);
 #endif