tests: bsim: bluetooth: host: add hci driver stress test

This commit adds a stress test to verify that the HCI driver does not
drop any data. Specifically, it tests whether the HCI IPC driver can
reliably pass data between the Host and Controller.

Due to the current HCI IPC driver implementation, this test is
guaranteed to fail if Controller-to-Host HCI ACL data flow control is
disabled.

Signed-off-by: Pavel Vasilyev <pavel.vasilyev@nordicsemi.no>
(cherry picked from commit a43b893)
Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>

Author: PavelVPV

tests/bsim/bluetooth/host/gatt/notify_stress/CMakeLists.txt

@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(bsim_test_gatt)
+
+add_subdirectory(${ZEPHYR_BASE}/tests/bsim/babblekit babblekit)
+target_link_libraries(app PRIVATE babblekit)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources} )
+
+zephyr_include_directories(
+  ${BSIM_COMPONENTS_PATH}/libUtilv1/src/
+  ${BSIM_COMPONENTS_PATH}/libPhyComv1/src/
+  )

tests/bsim/bluetooth/host/gatt/notify_stress/Kconfig.sysbuild

@@ -0,0 +1,14 @@
+# Copyright 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+source "share/sysbuild/Kconfig"
+
+config NET_CORE_BOARD
+	string
+	default "nrf5340bsim/nrf5340/cpunet" if $(BOARD_TARGET_STRING) = "NRF5340BSIM_NRF5340_CPUAPP"
+
+config NATIVE_SIMULATOR_PRIMARY_MCU_INDEX
+	int
+	# Let's pass the test arguments to the application MCU test
+	# otherwise by default they would have gone to the net core.
+	default 0 if $(BOARD_TARGET_STRING) = "NRF5340BSIM_NRF5340_CPUAPP"

tests/bsim/bluetooth/host/gatt/notify_stress/nrf5340_cpunet-bt_ll_sw_split.conf

@@ -0,0 +1,30 @@
+CONFIG_IPC_SERVICE=y
+CONFIG_MBOX=y
+CONFIG_ISR_STACK_SIZE=1024
+CONFIG_IDLE_STACK_SIZE=256
+CONFIG_MAIN_STACK_SIZE=512
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=512
+CONFIG_IPC_SERVICE_BACKEND_RPMSG_WQ_STACK_SIZE=512
+CONFIG_HEAP_MEM_POOL_SIZE=4096
+CONFIG_CBPRINTF_REDUCED_INTEGRAL=y
+CONFIG_ISR_TABLES_LOCAL_DECLARATION=y
+
+CONFIG_BT=y
+CONFIG_BT_HCI_RAW=y
+CONFIG_BT_MAX_CONN=1
+
+# Controller
+CONFIG_BT_LL_SW_SPLIT=y
+CONFIG_BT_CTLR_ASSERT_HANDLER=y
+
+CONFIG_BT_CTLR_DATA_LENGTH_MAX=70
+CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=191
+CONFIG_BT_CTLR_RX_BUFFERS=10
+
+CONFIG_BT_BUF_CMD_TX_SIZE=65
+CONFIG_BT_BUF_EVT_RX_SIZE=68
+CONFIG_BT_BUF_EVT_RX_COUNT=17
+CONFIG_BT_BUF_ACL_TX_COUNT=16
+CONFIG_BT_BUF_ACL_TX_SIZE=70
+CONFIG_BT_BUF_ACL_RX_SIZE=70
+CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA=1

tests/bsim/bluetooth/host/gatt/notify_stress/prj.conf

@@ -0,0 +1,35 @@
+CONFIG_BT=y
+CONFIG_BT_DEVICE_NAME="GATT tester"
+CONFIG_BT_PERIPHERAL=y
+CONFIG_BT_CENTRAL=y
+CONFIG_BT_GATT_CLIENT=y
+
+CONFIG_BT_GATT_AUTO_DISCOVER_CCC=y
+
+CONFIG_BT_SMP=y
+CONFIG_BT_L2CAP_DYNAMIC_CHANNEL=y
+CONFIG_BT_L2CAP_ECRED=y
+CONFIG_BT_EATT=y
+
+CONFIG_BT_AUTO_PHY_UPDATE=n
+CONFIG_BT_AUTO_DATA_LEN_UPDATE=n
+
+CONFIG_ASSERT=y
+CONFIG_BT_TESTING=y
+CONFIG_LOG=y
+
+# Maximum possible EATT channels are used to parallelize notifications as much as possible,
+# increasing traffic towards Central.
+CONFIG_BT_EATT_MAX=16
+
+# This is aligned with CONFIG_BT_EATT_MAX to utilize all EATT channels
+CONFIG_BT_BUF_ACL_TX_COUNT=16
+
+# Aligned with characteristic size
+CONFIG_BT_BUF_ACL_RX_SIZE=70
+CONFIG_BT_BUF_ACL_TX_SIZE=70
+
+CONFIG_BT_BUF_EVT_RX_COUNT=17
+CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA=1
+
+CONFIG_BT_BUF_CMD_TX_COUNT=2

tests/bsim/bluetooth/host/gatt/notify_stress/src/common.h

@@ -0,0 +1,21 @@
+/**
+ * Common macros used by both sides of the test
+ *
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/toolchain.h>
+
+#define CHRC_SIZE 60
+
+#define TEST_SERVICE_UUID                                                                          \
+	BT_UUID_DECLARE_128(0x01, 0x23, 0x45, 0x67, 0x89, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,      \
+			    0x07, 0x08, 0x09, 0x00, 0x00)
+
+#define TEST_CHRC_UUID                                                                             \
+	BT_UUID_DECLARE_128(0x01, 0x23, 0x45, 0x67, 0x89, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,      \
+			    0x07, 0x08, 0x09, 0xFF, 0x11)
+
+#define NOTIFICATION_COUNT 30