sample: board: sensortile_box_pro: add ble-fw-upgrade

This sample implement the ble firmware upgrade using the AN5471
protocol on uart2 channel.

Signed-off-by: Armando Visconti <armando.visconti@st.com>

samples/boards/sensortile_box_pro/ble-fw-upgrade/CMakeLists.txt

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+# Copyright (c) 2024 STMicroelectronics
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(sensortile_box_pro)
+
+target_sources(app PRIVATE src/main.c)
+target_sources(app PRIVATE src/ble_fw.c)

samples/boards/sensortile_box_pro/ble-fw-upgrade/README.rst

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+.. zephyr:code-sample:: sensortile_box_pro_sample_ble_fwupg
+   :name: ST SensorTile.box Pro BLE Firmware Upgrade
+
+   Upgrade the BLE firmware on STEVAL-MKBOXPRO board
+
+Overview
+********
+This sample provides a simple method to upgrade the firmware for
+the BLE chip present on :ref:`sensortile_box_pro_board` board.
+It is based on the BlueNRG-LPS UART bootloader protocol explained in `AN5471`_ .
+
+Requirements
+************
+
+The application requires a SensorTile.box Pro board connected to the PC
+through USB.
+
+To run this sample the console is not strictly needed, but might be useful.
+Following is an example for minicom.
+
+.. code-block:: console
+
+   $ minicom -D <tty_device> -b 115200
+
+Replace :code:`<tty_device>` with the correct device path automatically created on
+the host after the SensorTile.box Pro board gets connected to it,
+usually :samp:`/dev/ttyUSB{x}` or :samp:`/dev/ttyACM{x}` (with x being 0, 1, 2, ...).
+The ``-b`` option sets baud rate ignoring the value from config.
+
+Building and Running
+********************
+
+To build and flash the sample, it is required fetching the controller-only BLE f/w
+image for sensortile_box_pro board, which is hosted by external repo
+(see `stsw-mkbox-bleco`_ for more information):
+
+To fetch Binary Blobs:
+
+.. code-block:: console
+
+   west blobs fetch stm32
+
+Then, build the sample:
+
+.. zephyr-app-commands::
+    :zephyr-app: samples/boards/sensortile_box_pro/ble-fw-upgrade
+    :board: sensortile_box_pro
+    :goals: build flash
+
+Please note that flashing the board requires a few preliminary steps described
+in :ref:`sensortile_box_pro_board`.
+
+After flashing, the sample starts and asks the user to acknowledge the f/w update.
+User should press :kbd:`y` or :kbd:`Y` to proceed in upgrading the BLE f/w.
+
+ .. code-block:: console
+
+    Start BLE f/w update (press Y to proceed):
+
+Nevertheless it is not strictly necessary to use the console, as the user may also acknowledge
+the f/w update pressing the User BT2 button (see :ref:`sensortile_box_pro_board` board and
+check on user manual and/or schematic to see where the button is located and how
+it works).
+
+LEDs status
+-----------
+
+The blue LED blinks three times with 200ms interval to indicate the procedure is starting.
+Then blue LED start blinking very fast to indicate the BLE flash activity is on going.
+
+After BLE flashing is complete:
+
+- If status is OK the green LED blinks three times with 200ms interval and remains on.
+- If flashing failed the red LED blinks three times with 200ms interval and remains on.
+
+Console messages
+----------------
+
+To properly see messages on your terminale emulatore you may also need to set lineWrap to on.
+In case of minicom just enter the menu with :kbd:`Ctrl-A Z` an then press :kbd:`W`.
+
+The sample outputs following messages.
+
+ .. code-block:: console
+
+    SensorTile.box Pro BLE f/w upgrade
+    bootloader activated!
+    ble bootloader version is 4.0
+    MASS ERASE ok
+    ..............................................................................................
+    ..............................................................................................
+    ..............................................................................................
+    ..............................................................................................
+    ..............................................................................................
+    ..............................................................................................
+    ..............................................................................................
+    ............................................
+    BLE f/w upgrade ok
+
+References
+**********
+
+.. target-notes::
+
+.. _AN5471:
+   https://www.st.com/resource/en/application_note/an5471-the-bluenrglp-bluenrglps-uart-bootloader-protocol-stmicroelectronics.pdf
+
+.. _stsw-mkbox-bleco:
+   https://www.st.com/en/embedded-software/stsw-mkbox-bleco.html

samples/boards/sensortile_box_pro/ble-fw-upgrade/prj.conf

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+CONFIG_GPIO=y
+CONFIG_LOG=y

samples/boards/sensortile_box_pro/ble-fw-upgrade/sample.yaml

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+sample:
+  description: SensorTile.box Pro board ble firmware upgrade
+  name: SensorTile.box Pro fw upgrade
+tests:
+  sample.board.sensortile_box_pro.ble-fw-upgrade:
+    harness: bluetooth
+    platform_allow: sensortile_box_pro
+    tags: bluetooth
+    depends_on:
+      - gpio
+      - uart
+    # This test cannot be run in CI as it requires the presence of a
+    # f/w blob that is not fetched by CI iself, as mentioned in
+    # https://docs.zephyrproject.org/latest/contribute/bin_blobs.html#support-and-maintenance
+    skip: true

samples/boards/sensortile_box_pro/ble-fw-upgrade/src/ble_fw.c

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+/*
+ * Copyright (c) 2024 STMicroelectronics
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdint.h>
+
+const uint8_t ble_fw_img[] = {
+#include <dtm.bin.inc>
+};
+
+const uint32_t ble_fw_img_len = sizeof(ble_fw_img);