tests bsim bt: Add basic connection test with HCI UART async controllers

Add a basic connection test between two devices,
in which the controllers are in separate nrf52_bsim devices
connected over UART to the devices running the host+app.
The controllers are running the HCI UART async sample.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

samples/bluetooth/hci_uart_async/boards/nrf52_bsim.overlay

@@ -0,0 +1 @@
+/* Purposely empty. To avoid using the one provided by the application */

tests/bsim/bluetooth/hci_uart/compile.sh

@@ -20,5 +20,6 @@ source ${ZEPHYR_BASE}/tests/bsim/compile.source
 
 app=tests/bsim/bluetooth/ll/conn conf_file=prj_split_uart.conf compile
 app=samples/bluetooth/hci_uart compile
+app=samples/bluetooth/hci_uart_async compile
 
 wait_for_background_jobs

tests/bsim/bluetooth/hci_uart/tests_scripts/basic_conn_split_uart_async.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+# Copyright 2024 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+source ${ZEPHYR_BASE}/tests/bsim/sh_common.source
+
+# Basic connection test: a central connects to a peripheral and expects a
+# notification, using the split controller (ULL LLL)
+# Both central and peripheral hosts have their controllers in a separate device
+# connected over UART. The controller is the HCI UART async sample.
+simulation_id="basic_conn_split_uart_async"
+verbosity_level=2
+EXECUTE_TIMEOUT=10
+
+cd ${BSIM_OUT_PATH}/bin
+
+UART_DIR=/tmp/bs_${USER}/${simulation_id}/
+UART_PER=${UART_DIR}/peripheral
+UART_CEN=${UART_DIR}/central
+
+# Note the host+app devices are NOT connected to the phy, only the controllers are.
+
+# Peripheral app + host :
+Execute ./bs_${BOARD}_tests_bsim_bluetooth_ll_conn_prj_split_uart_conf \
+  -v=${verbosity_level} -s=${simulation_id} -d=10 -nosim -RealEncryption=0 \
+  -testid=peripheral -rs=23 -uart1_fifob_rxfile=${UART_PER}.rx -uart1_fifob_txfile=${UART_PER}.tx
+
+# Peripheral controller:
+Execute ./bs_${BOARD}_samples_bluetooth_hci_uart_async_prj_conf \
+  -v=${verbosity_level} -s=${simulation_id} -d=0 -RealEncryption=0 \
+  -rs=23 -uart1_fifob_rxfile=${UART_PER}.tx -uart1_fifob_txfile=${UART_PER}.rx
+
+# Central app + host
+Execute ./bs_${BOARD}_tests_bsim_bluetooth_ll_conn_prj_split_uart_conf\
+  -v=${verbosity_level} -s=${simulation_id} -d=11 -nosim -RealEncryption=0 \
+  -testid=central -rs=6 -uart1_fifob_rxfile=${UART_CEN}.rx -uart1_fifob_txfile=${UART_CEN}.tx
+
+# Central controller:
+Execute ./bs_${BOARD}_samples_bluetooth_hci_uart_async_prj_conf \
+  -v=${verbosity_level} -s=${simulation_id} -d=1 -RealEncryption=0 \
+  -rs=23 -uart1_fifob_rxfile=${UART_CEN}.tx -uart1_fifob_txfile=${UART_CEN}.rx
+
+Execute ./bs_2G4_phy_v1 -v=${verbosity_level} -s=${simulation_id} \
+  -D=2 -sim_length=20e6 $@
+
+wait_for_background_jobs