softdevice: add babblesim support

Add SoftDevice babblesim support.

Signed-off-by: Emanuele Di Santo <emdi@nordicsemi.no>

Author: lemrey

samples/Kconfig

@@ -8,7 +8,7 @@
 
 # All these samples shall run without multithreading
 config MULTITHREADING
-	default n if (!UNITY && !(ZTEST && BOARD_NATIVE_SIM))
+	default n if (!UNITY && !(ZTEST && BOARD_NATIVE_SIM) && !SOC_SERIES_BSIM_NRF54LX)
 
 # Software ISR table is not needed if multithreading is not used
 config GEN_SW_ISR_TABLE

subsys/softdevice/CMakeLists.txt

@@ -7,3 +7,8 @@
 if(CONFIG_SOFTDEVICE_S115 OR CONFIG_SOFTDEVICE_S145)
   zephyr_include_directories("${ZEPHYR_NRF_BM_MODULE_DIR}/components/softdevice/${CONFIG_SOFTDEVICE_SOC_VARIANT_STR}/${CONFIG_SOFTDEVICE_VARIANT_STR}/${CONFIG_SOFTDEVICE_VARIANT_STR}_API/include")
 endif()
+
+# SVCALL_AS_NORMAL_FUNCTION makes BLE API headers declare normal functions (no ARM SVC asm).
+if(CONFIG_SOFTDEVICE_BSIM)
+  zephyr_compile_definitions(SVCALL_AS_NORMAL_FUNCTION)
+endif()

subsys/softdevice/Kconfig

@@ -7,7 +7,7 @@ menu "SoftDevice"
 
 config SOFTDEVICE
 	bool "SoftDevice is present"
-	depends on ZERO_LATENCY_IRQS
+	depends on ZERO_LATENCY_IRQS || SOC_SERIES_BSIM_NRF54LX
 	imply NRF_SDH
 
 config SOFTDEVICE_PERIPHERAL
@@ -32,20 +32,26 @@ choice SOFTDEVICE_VARIANT
 
 config SOFTDEVICE_S115
 	bool "s115 SoftDevice"
-	depends on SOC_SERIES_NRF54L
+	depends on SOC_SERIES_NRF54L || SOC_SERIES_BSIM_NRF54LX
 	select SOFTDEVICE_PERIPHERAL
 	select SOFTDEVICE_DATA_LENGTH_UPDATE
 
 config SOFTDEVICE_S145
 	bool "s145 SoftDevice"
-	depends on SOC_SERIES_NRF54L
+	depends on SOC_SERIES_NRF54L || SOC_SERIES_BSIM_NRF54LX
 	select SOFTDEVICE_PERIPHERAL
 	select SOFTDEVICE_CENTRAL
 	select SOFTDEVICE_EXTENDED_ADVERTISING
 	select SOFTDEVICE_DATA_LENGTH_UPDATE
 
 endchoice # SOFTDEVICE_VARIANT
 
+config SOFTDEVICE_BSIM
+	bool "Use linkable SoftDevice for Babblesim"
+	depends on SOC_SERIES_BSIM_NRF54LX
+	help
+	  Link with the SoftDevice library instead of using the separate SoftDevice hex image.
+
 config SOFTDEVICE_VARIANT_STR
 	string
 	default "s115" if SOFTDEVICE_S115
@@ -56,7 +62,7 @@ config SOFTDEVICE_VARIANT_STR
 
 config SOFTDEVICE_SOC_VARIANT_STR
 	string
-	default "nrf54l" if SOC_NRF54L15 || SOC_NRF54L10 || SOC_NRF54L05
+	default "nrf54l" if SOC_NRF54L15 || SOC_NRF54L10 || SOC_NRF54L05 || SOC_SERIES_BSIM_NRF54LX
 	default "nrf54lm" if SOC_NRF54LM20A
 	default "nrf54ls" if SOC_NRF54LS05B
 	default "nrf54lv" if SOC_NRF54LV10A

subsys/softdevice_handler/CMakeLists.txt

@@ -6,18 +6,24 @@
 zephyr_library()
 zephyr_linker_sources(SECTIONS sdh.ld)
 zephyr_linker_sources(DATA_SECTIONS sdh_ram.ld)
+
 zephyr_library_sources(
   nrf_sdh.c
   nrf_sdh_info.c
   nrf_sdh_soc.c
-  irq_connect.c
 )
 
+zephyr_library_sources_ifdef(CONFIG_NRF_SDH_BLE nrf_sdh_ble.c)
 zephyr_library_sources_ifdef(CONFIG_NRF_SDH_SOC_RAND_SEED rand_seed.c)
 
-if(CONFIG_SOFTDEVICE_S115 OR CONFIG_SOFTDEVICE_S145)
-  zephyr_library_sources(irq_forward.s)
+# IRQ setup
+if(CONFIG_SOFTDEVICE_BSIM)
+  zephyr_library_sources(irq_connect_bsim.c)
+else()
+  # ARM-only: IRQ connection, SVC forwarding and swap_helper suppression
   # Suppress the swap_helper.S file so that z_arm_svc can be defined manually
+  zephyr_library_sources(irq_connect.c)
+  zephyr_library_sources(irq_forward.s)
   set(cortex_m_dir ${ZEPHYR_BASE}/arch/arm/core/cortex_m)
   set_property(
     SOURCE ${cortex_m_dir}/swap_helper.S
@@ -26,7 +32,3 @@ if(CONFIG_SOFTDEVICE_S115 OR CONFIG_SOFTDEVICE_S145)
   )
   target_link_options(app PUBLIC "-Wl,--defsym=z_arm_svc=SVC_Handler")
 endif()
-
-if(CONFIG_NRF_SDH_BLE)
-  zephyr_library_sources(nrf_sdh_ble.c)
-endif()

subsys/softdevice_handler/Kconfig

@@ -237,8 +237,7 @@ endif # NRF_SDH_BLE
 
 config NRF_SDH_SOC_RAND_SEED
 	bool "Automatically seed SoftDevice random"
-	depends on NRF_SECURITY
-	depends on MBEDTLS_PSA_CRYPTO_C
+	depends on (NRF_SECURITY && MBEDTLS_PSA_CRYPTO_C) || SOC_SERIES_BSIM_NRF54LX
 	default y
 	help
 	  Automatically seed SoftDevice using CRACEN to generate the random seed.

subsys/softdevice_handler/irq_connect.c

@@ -14,9 +14,9 @@
 
 LOG_MODULE_DECLARE(nrf_sdh, CONFIG_NRF_SDH_LOG_LEVEL);
 
-#if CONFIG_SOC_SERIES_NRF54L
 #include "irq_connect.h"
 
+/* Handlers provided by the SoftDevice */
 extern void CLOCK_POWER_SD_IRQHandler(void);
 extern void RADIO_0_IRQHandler(void);
 extern void TIMER10_IRQHandler(void);
@@ -121,6 +121,4 @@ __attribute__((weak)) void C_CLOCK_POWER_SD_Handler(void)
 #endif
 }
 
-#endif /* CONFIG_SOC_SERIES_NRF54L */
-
 SYS_INIT(irq_init, APPLICATION, 0);

subsys/softdevice_handler/irq_connect_bsim.c

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2026 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ *
+ * Register all SoftDevice IRQ handlers with the native simulator.
+ * SD_EVT_IRQn (SWI01) is connected in nrf_sdh.c (sd_irq_init), same as on ARM.
+ */
+
+#include <nrfx.h>
+#include <zephyr/init.h>
+#include <zephyr/irq.h>
+
+/* Handlers provided by the linked SoftDevice library */
+extern void C_RTC0_Handler(void);
+extern void C_SIGNALLING_Handler(void);
+extern void C_RADIO_Handler(void);
+extern void C_POWER_CLOCK_Handler(void);
+extern void C_TIMER0_Handler(void);
+extern void C_ECB_Handler(void);
+extern void C_CCM_Handler(void);
+
+#define SD_IRQ_PRIO_HIGH 0
+#define SD_IRQ_PRIO_LOW 4
+
+#define IRQ_WRAPPER(name, handler) \
+	static void name##_wrapper(const void *arg) { ARG_UNUSED(arg); handler(); }
+
+IRQ_WRAPPER(grtc3, C_RTC0_Handler);
+IRQ_WRAPPER(swi00, C_SIGNALLING_Handler);
+IRQ_WRAPPER(radio0, C_RADIO_Handler);
+
+IRQ_WRAPPER(clock_power, C_POWER_CLOCK_Handler);
+IRQ_WRAPPER(timer10, C_TIMER0_Handler);
+IRQ_WRAPPER(ecb00, C_ECB_Handler);
+IRQ_WRAPPER(aar00_ccm00, C_CCM_Handler);
+
+#define REGISTER(irqn, irqp, wrapper) do { \
+	(void)irq_connect_dynamic(irqn, irqp, wrapper##_wrapper, NULL, 0); \
+	irq_enable(irqn); \
+} while (0)
+
+static int softdevice_bsim_irq_init(void)
+{
+	REGISTER(GRTC_3_IRQn, SD_IRQ_PRIO_HIGH, grtc3);
+	REGISTER(TIMER10_IRQn, SD_IRQ_PRIO_HIGH, timer10);
+	REGISTER(RADIO_0_IRQn, SD_IRQ_PRIO_HIGH, radio0);
+
+	REGISTER(SWI00_IRQn, SD_IRQ_PRIO_LOW, swi00);
+	REGISTER(CLOCK_POWER_IRQn, SD_IRQ_PRIO_LOW, clock_power);
+	REGISTER(ECB00_IRQn, SD_IRQ_PRIO_LOW, ecb00);
+	REGISTER(AAR00_CCM00_IRQn, SD_IRQ_PRIO_LOW, aar00_ccm00);
+
+	return 0;
+}
+
+SYS_INIT(softdevice_bsim_irq_init, APPLICATION, 0);

subsys/softdevice_handler/nrf_sdh.c

@@ -6,6 +6,7 @@
 #include <stdint.h>
 #include <nrf_sdm.h>
 #include <nrf_soc.h>
+#include <nrfx.h>
 #include <bm/softdevice_handler/nrf_sdh.h>
 #include <bm/softdevice_handler/nrf_sdh_info.h>
 #include <bm/bm_irq.h>
@@ -131,7 +132,8 @@ static int nrf_sdh_enable(void)
 		.hfint_ctiv = CONFIG_NRF_SDH_CLOCK_HFINT_CALIBRATION_INTERVAL,
 	};
 
-	if (IS_ENABLED(CONFIG_NRF_SDH_LOG_SD_INFO)) {
+#if defined(CONFIG_NRF_SDH_LOG_SD_INFO) && !defined(CONFIG_SOFTDEVICE_BSIM)
+	{
 		const uint32_t base = FIXED_PARTITION_OFFSET(softdevice_partition);
 		const struct nrf_sdh_info_version sd_ver = nrf_sdh_info_version_get(base);
 		const struct nrf_sdh_info_unique_str sd_unique = nrf_sdh_info_unique_str_get(base);
@@ -149,6 +151,7 @@ static int nrf_sdh_enable(void)
 				sd_ver.bugfix);
 		}
 	}
+#endif
 
 	err = sd_softdevice_enable(&clock_lf_cfg, softdevice_fault_handler);
 	if (err) {
@@ -392,8 +395,7 @@ ISR_DIRECT_DECLARE(sd_direct_isr)
 
 static int sd_irq_init(void)
 {
-	BM_IRQ_DIRECT_CONNECT(SD_EVT_IRQn, SD_EVT_IRQ_PRI,
-			      sd_direct_isr, 0);
+	BM_IRQ_DIRECT_CONNECT(SD_EVT_IRQn, SD_EVT_IRQ_PRI, sd_direct_isr, 0);
 	irq_enable(SD_EVT_IRQn);
 
 	return 0;

subsys/softdevice_handler/nrf_sdh_ble.c

@@ -12,8 +12,15 @@
 #include <bm/softdevice_handler/nrf_sdh_ble.h>
 #include <zephyr/logging/log.h>
 
+#if defined(CONFIG_SOFTDEVICE_BSIM)
+extern uint32_t g_app_ram_base;
+extern uint32_t bsim_softdevice_ram_end;
+#define APP_RAM_START (bsim_softdevice_ram_end)
+#define SD_RAM_START  (g_app_ram_base)
+#else
 #define APP_RAM_START DT_REG_ADDR(DT_CHOSEN(zephyr_sram))
 #define SD_RAM_START DT_REG_ADDR(DT_NODELABEL(cpuapp_sram))
+#endif
 
 LOG_MODULE_DECLARE(nrf_sdh, CONFIG_NRF_SDH_LOG_LEVEL);
 

subsys/softdevice_handler/rand_seed.c

@@ -7,17 +7,16 @@
 #include <nrf_soc.h>
 #include <bm/softdevice_handler/nrf_sdh_soc.h>
 #include <zephyr/logging/log.h>
-#include <psa/crypto.h>
 #if CONFIG_HAS_HW_NRF_CRACEN
+#include <psa/crypto.h>
 #include <cracen_psa.h>
-#else
+#elif CONFIG_NRFX_CRACEN
 #include <nrfx_cracen.h>
 #endif
 
 LOG_MODULE_DECLARE(nrf_sdh, CONFIG_NRF_SDH_LOG_LEVEL);
 
-/* Extern in nrf_sdh.c */
-void sdh_soc_rand_seed(uint32_t evt, void *ctx)
+static void sdh_soc_rand_seed(uint32_t evt, void *ctx)
 {
 	uint32_t nrf_err;
 	uint8_t seed[SD_RAND_SEED_SIZE];
@@ -37,7 +36,7 @@ void sdh_soc_rand_seed(uint32_t evt, void *ctx)
 		LOG_ERR("Failed to generate true random number, psa_status %d", status);
 		return;
 	}
-#else
+#elif CONFIG_NRFX_CRACEN && !CONFIG_SOFTDEVICE_BSIM
 	/* Selected when we don't have CRACEN Crypto HW available, like for nRF54LS05B
 	 * In this case the cracen_psa api isn't available and we should use nrfx api
 	 */
@@ -47,6 +46,8 @@ void sdh_soc_rand_seed(uint32_t evt, void *ctx)
 		LOG_ERR("Failed to generate true random number, err %d", err);
 		return;
 	}
+#elif CONFIG_SOFTDEVICE_BSIM
+	/* Seed with heap garbage */
 #endif
 
 	nrf_err = sd_rand_seed_set(seed);