mbed-os/features/lorawan/LoRaWANStack.cpp

/**
 / _____)             _              | |
( (____  _____ ____ _| |_ _____  ____| |__
 \____ \| ___ |    (_   _) ___ |/ ___)  _ \
 _____) ) ____| | | || |_| ____( (___| | | |
(______/|_____)_|_|_| \__)_____)\____)_| |_|
    (C)2013 Semtech
 ___ _____ _   ___ _  _____ ___  ___  ___ ___
/ __|_   _/_\ / __| |/ / __/ _ \| _ \/ __| __|
\__ \ | |/ _ \ (__| ' <| _| (_) |   / (__| _|
|___/ |_/_/ \_\___|_|\_\_| \___/|_|_\\___|___|
embedded.connectivity.solutions===============

Description: LoRaWAN stack layer that controls both MAC and PHY underneath

License: Revised BSD License, see LICENSE.TXT file include in the project

Maintainer: Miguel Luis ( Semtech ), Gregory Cristian ( Semtech ) and Daniel Jaeckle ( STACKFORCE )


Copyright (c) 2017, Arm Limited and affiliates.

SPDX-License-Identifier: BSD-3-Clause
*/

#include <string.h>
#include <stdlib.h>
#include "platform/Callback.h"
#include "events/EventQueue.h"

#include "LoRaWANStack.h"

#include "mbed-trace/mbed_trace.h"
#define TRACE_GROUP "LSTK"

#define INVALID_PORT                0xFF
#define MAX_CONFIRMED_MSG_RETRIES   255
/**
 * Control flags for transient states
 */
#define IDLE_FLAG                   0x00000000
#define TX_ONGOING_FLAG             0x00000001
#define MSG_RECVD_FLAG              0x00000002
#define CONNECTED_FLAG              0x00000004
#define USING_OTAA_FLAG             0x00000008
#define TX_DONE_FLAG                0x00000010

using namespace mbed;
using namespace events;

#if defined(LORAWAN_COMPLIANCE_TEST)
    #if (MBED_CONF_LORA_PHY == 0 || MBED_CONF_LORA_PHY == 4 || MBED_CONF_LORA_PHY == 6 || MBED_CONF_LORA_PHY == 7)
        #define LORAWAN_COMPLIANCE_TEST_DATA_SIZE                  16
    #elif (MBED_CONF_LORA_PHY == 1 || MBED_CONF_LORA_PHY == 2 || MBED_CONF_LORA_PHY == 8 || MBED_CONF_LORA_PHY == 9)
        #define LORAWAN_COMPLIANCE_TEST_DATA_SIZE                  11
    #else
        #error "Must set LoRa PHY layer parameters."
    #endif
#endif

/**
 * Bit mask for message flags
 */

#define MSG_FLAG_MASK                         0x0F

/*****************************************************************************
 * Constructor                                                               *
 ****************************************************************************/
LoRaWANStack::LoRaWANStack()
: _loramac(),
  _device_current_state(DEVICE_STATE_NOT_INITIALIZED),
  _lw_session(),
  _tx_msg(),
  _rx_msg(),
  _num_retry(1),
  _ctrl_flags(IDLE_FLAG),
  _app_port(INVALID_PORT),
  _link_check_requested(false),
  _automatic_uplink_ongoing(false),
  _ready_for_rx(true),
  _queue(NULL)
{
#ifdef MBED_CONF_LORA_APP_PORT
    if (is_port_valid(MBED_CONF_LORA_APP_PORT)) {
        _app_port = MBED_CONF_LORA_APP_PORT;
    } else {
        tr_error("User defined port in .json is illegal.");
    }
#endif
}

/*****************************************************************************
 * Public Methods                                                            *
 ****************************************************************************/
void LoRaWANStack::bind_radio_driver(LoRaRadio& radio)
{
    radio_events.tx_done = mbed::callback(this, &LoRaWANStack::tx_interrupt_handler);
    radio_events.rx_done = mbed::callback(this, &LoRaWANStack::rx_interrupt_handler);
    radio_events.rx_error = mbed::callback(this, &LoRaWANStack::rx_error_interrupt_handler);
    radio_events.tx_timeout = mbed::callback(this, &LoRaWANStack::tx_timeout_interrupt_handler);
    radio_events.rx_timeout = mbed::callback(this, &LoRaWANStack::rx_timeout_interrupt_handler);

    _loramac.bind_radio_driver(radio);

    radio.lock();
    radio.init_radio(&radio_events);
    radio.unlock();
}

lorawan_status_t LoRaWANStack::initialize_mac_layer(EventQueue *queue)
{
    if(!queue) {
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }

    tr_debug("Initializing MAC layer");
    _queue = queue;

    return state_controller(DEVICE_STATE_IDLE);
}

lorawan_status_t LoRaWANStack::set_lora_callbacks(const lorawan_app_callbacks_t *callbacks)
{
    if (!callbacks || !callbacks->events) {
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }

    _callbacks.events = callbacks->events;

    if (callbacks->link_check_resp) {
        _callbacks.link_check_resp = callbacks->link_check_resp;
    }

    if (callbacks->battery_level) {
        _callbacks.battery_level = callbacks->battery_level;
        _loramac.set_batterylevel_callback(callbacks->battery_level);
    }

    return LORAWAN_STATUS_OK;
}

lorawan_status_t LoRaWANStack::connect()
{
    if (DEVICE_STATE_NOT_INITIALIZED == _device_current_state) {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    lorawan_status_t status = _loramac.prepare_join(NULL, MBED_CONF_LORA_OVER_THE_AIR_ACTIVATION);

    if (LORAWAN_STATUS_OK != status) {
        return status;
    }

    return handle_connect(MBED_CONF_LORA_OVER_THE_AIR_ACTIVATION);
}

lorawan_status_t LoRaWANStack::connect(const lorawan_connect_t &connect)
{
    if (DEVICE_STATE_NOT_INITIALIZED == _device_current_state) {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    if (!(connect.connect_type == LORAWAN_CONNECTION_OTAA) &&
        !(connect.connect_type == LORAWAN_CONNECTION_ABP)) {
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }
    bool is_otaa = (connect.connect_type == LORAWAN_CONNECTION_OTAA);

    lorawan_status_t status = _loramac.prepare_join(&connect, is_otaa);

    if (LORAWAN_STATUS_OK != status) {
        return status;
    }

    return handle_connect(is_otaa);
}

lorawan_status_t LoRaWANStack::add_channels(const lorawan_channelplan_t &channel_plan)
{
    if (_device_current_state == DEVICE_STATE_NOT_INITIALIZED) {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    return _loramac.add_channel_plan(channel_plan);
}

lorawan_status_t LoRaWANStack::remove_a_channel(uint8_t channel_id)
{
    if (_device_current_state == DEVICE_STATE_NOT_INITIALIZED) {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    return _loramac.remove_single_channel(channel_id);
}

lorawan_status_t LoRaWANStack::drop_channel_list()
{
    if (_device_current_state == DEVICE_STATE_NOT_INITIALIZED) {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    return _loramac.remove_channel_plan();
}

lorawan_status_t LoRaWANStack::get_enabled_channels(lorawan_channelplan_t& channel_plan)
{
    if (_device_current_state == DEVICE_STATE_NOT_INITIALIZED) {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    return _loramac.get_channel_plan(channel_plan);
}

lorawan_status_t LoRaWANStack::set_confirmed_msg_retry(uint8_t count)
{
    if (count >= MAX_CONFIRMED_MSG_RETRIES) {
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }

    _num_retry = count;

    return LORAWAN_STATUS_OK;
}

lorawan_status_t LoRaWANStack::set_channel_data_rate(uint8_t data_rate)
{
    if (DEVICE_STATE_NOT_INITIALIZED == _device_current_state)
    {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }

    return _loramac.set_channel_data_rate(data_rate);
}


lorawan_status_t LoRaWANStack::enable_adaptive_datarate(bool adr_enabled)
{
    if (_device_current_state == DEVICE_STATE_NOT_INITIALIZED)
    {
        tr_error("Stack not initialized!");
        return LORAWAN_STATUS_NOT_INITIALIZED;
    }
    _loramac.enable_adaptive_datarate(adr_enabled);
    return LORAWAN_STATUS_OK;
}

int16_t LoRaWANStack::handle_tx(const uint8_t port, const uint8_t* data,
                                uint16_t length, uint8_t flags,
                                bool null_allowed, bool allow_port_0)
{
    if (!null_allowed && !data) {
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }
    // add a link check request with normal data, until the application
    // explicitly removes it.
    if (_link_check_requested) {
        set_link_check_request();
    }

    if (!_lw_session.active) {
        return LORAWAN_STATUS_NO_ACTIVE_SESSIONS;
    }

    if(_loramac.tx_ongoing()) {
        return LORAWAN_STATUS_WOULD_BLOCK;
    }

#if defined(LORAWAN_COMPLIANCE_TEST)
    if (_compliance_test.running) {
        return LORAWAN_STATUS_COMPLIANCE_TEST_ON;
    }
#endif

    lorawan_status_t status;

    if (_loramac.nwk_joined() == false) {
        return LORAWAN_STATUS_NO_NETWORK_JOINED;
    }

    status = set_application_port(port, allow_port_0);

    if (status != LORAWAN_STATUS_OK) {
        tr_error("Illegal application port definition.");
        return status;
    }

    // All the flags mutually exclusive. In addition to that MSG_MULTICAST_FLAG cannot be
    // used for uplink.
    switch (flags & MSG_FLAG_MASK) {
        case MSG_UNCONFIRMED_FLAG:
        case MSG_CONFIRMED_FLAG:
        case MSG_PROPRIETARY_FLAG:
            break;

        default:
            tr_error("Invalid send flags");
            return LORAWAN_STATUS_PARAMETER_INVALID;
    }

    int16_t len = _loramac.prepare_ongoing_tx(port, data, length, flags, _num_retry);

    status = state_controller(DEVICE_STATE_SCHEDULING);

    // send user the length of data which is scheduled now.
    // user should take care of the pending data.
    return (status == LORAWAN_STATUS_OK) ? len : (int16_t) status;
}

int16_t LoRaWANStack::handle_rx(uint8_t* data, uint16_t length, uint8_t& port, int& flags, bool validate_params)
{
    if (!_lw_session.active) {
        return LORAWAN_STATUS_NO_ACTIVE_SESSIONS;
    }

    // No messages to read.
    if (!_rx_msg.receive_ready) {
        return LORAWAN_STATUS_WOULD_BLOCK;
    }

#if defined(LORAWAN_COMPLIANCE_TEST)
    if (_compliance_test.running) {
        return LORAWAN_STATUS_COMPLIANCE_TEST_ON;
    }
#endif

    if (data == NULL || length == 0) {
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }

    int received_flags = convert_to_msg_flag(_rx_msg.msg.mcps_indication.type);
    if (validate_params) {
        // Check received message port and flags match with the ones requested by user
        received_flags &= MSG_FLAG_MASK;

        if (_rx_msg.msg.mcps_indication.port != port || !(flags & received_flags)) {
            return LORAWAN_STATUS_WOULD_BLOCK;
        }
    }

    // Report values back to user
    port = _rx_msg.msg.mcps_indication.port;
    flags = received_flags;

    const uint8_t *base_ptr = _rx_msg.msg.mcps_indication.buffer;
    uint16_t base_size = _rx_msg.msg.mcps_indication.buffer_size;
    bool read_complete = false;

    // check the length of received message whether we can fit into user
    // buffer completely or not
    if (_rx_msg.msg.mcps_indication.buffer_size > length &&
        _rx_msg.prev_read_size == 0) {
        // we can't fit into user buffer. Invoke counter measures
        _rx_msg.pending_size = _rx_msg.msg.mcps_indication.buffer_size - length;
        base_size = length;
        _rx_msg.prev_read_size = base_size;
        memcpy(data, base_ptr, base_size);
    } else if (_rx_msg.prev_read_size == 0) {
        _rx_msg.pending_size = 0;
        _rx_msg.prev_read_size = 0;
        memcpy(data, base_ptr, base_size);
        read_complete = true;
    }

    // If its the pending read then we should copy only the remaining part of
    // the buffer. Due to checks above, in case of a pending read, this block
    // will be the only one to get invoked
    if (_rx_msg.pending_size > 0 && _rx_msg.prev_read_size > 0) {
        memcpy(data, base_ptr+_rx_msg.prev_read_size, base_size);
    }

    // we are done handing over received buffer to user. check if there is
    // anything pending. If not, memset the buffer to zero and indicate
    // that no read is in progress
    if (read_complete) {
        _rx_msg.msg.mcps_indication.buffer = NULL;
        _rx_msg.msg.mcps_indication.buffer_size = 0;
        _rx_msg.receive_ready = false;
    }

    return base_size;
}

lorawan_status_t LoRaWANStack::set_link_check_request()
{
    _link_check_requested = true;
    if (!_callbacks.link_check_resp) {
        tr_error("Must assign a callback function for link check request. ");
        return LORAWAN_STATUS_PARAMETER_INVALID;
    }

    _loramac.setup_link_check_request();
    return LORAWAN_STATUS_OK;
}

void LoRaWANStack::remove_link_check_request()
{
    _link_check_requested = false;
}

lorawan_status_t LoRaWANStack::shutdown()
{
    return state_controller(DEVICE_STATE_SHUTDOWN);
}

lorawan_status_t LoRaWANStack::set_device_class(const device_class_t& device_class)
{
    if (device_class == CLASS_B) {
        return LORAWAN_STATUS_UNSUPPORTED;
    }
    _loramac.set_device_class(device_class);
    return LORAWAN_STATUS_OK;
}

/*****************************************************************************
 * Interrupt handlers                                                        *
 ****************************************************************************/
void LoRaWANStack::tx_interrupt_handler(void)
{
    const int ret = _queue->call(this, &LoRaWANStack::process_transmission);
    MBED_ASSERT(ret != 0);
    (void)ret;
}

void LoRaWANStack::rx_interrupt_handler(const uint8_t *payload, uint16_t size,
                                        int16_t rssi, int8_t snr)
{
    if (!_ready_for_rx || size > sizeof _rx_payload) {
        return;
    }

    _ready_for_rx = false;
    memcpy(_rx_payload, payload, size);

    const uint8_t *ptr = _rx_payload;
    const int ret = _queue->call(this, &LoRaWANStack::process_reception,
                                 ptr, size, rssi, snr);
    MBED_ASSERT(ret != 0);
    (void)ret;
}

void LoRaWANStack::rx_error_interrupt_handler(void)
{
    const int ret = _queue->call(this, &LoRaWANStack::process_reception_timeout,
                                 false);
    MBED_ASSERT(ret != 0);
    (void)ret;
}

void LoRaWANStack::tx_timeout_interrupt_handler(void)
{
    const int ret = _queue->call(this, &LoRaWANStack::process_transmission_timeout);
    MBED_ASSERT(ret != 0);
    (void)ret;
}

void LoRaWANStack::rx_timeout_interrupt_handler(void)
{
    const int ret = _queue->call(this, &LoRaWANStack::process_reception_timeout,
                                 true);
    MBED_ASSERT(ret != 0);
    (void)ret;
}

/*****************************************************************************
 * Processors for deferred interrupts                                        *
 ****************************************************************************/
void LoRaWANStack::process_transmission_timeout()
{
    // this is a fatal error and should not happen
    tr_debug("TX Timeout");
    _loramac.on_radio_tx_timeout();
    _ctrl_flags &= ~TX_ONGOING_FLAG;
    _ctrl_flags |= TX_DONE_FLAG;
    state_controller(DEVICE_STATE_STATUS_CHECK);
    state_machine_run_to_completion();
}

void LoRaWANStack::process_transmission(void)
{
    _loramac.on_radio_tx_done();
    tr_debug("Transmission completed");

    if (_device_current_state == DEVICE_STATE_JOINING) {
        _device_current_state = DEVICE_STATE_AWAITING_JOIN_ACCEPT;
    }

    if (_device_current_state == DEVICE_STATE_SENDING) {
        if (_loramac.get_mcps_confirmation()->req_type == MCPS_CONFIRMED) {
            _ctrl_flags |= TX_ONGOING_FLAG;
            _ctrl_flags &= ~TX_DONE_FLAG;
            _device_current_state = DEVICE_STATE_AWAITING_ACK;
            return;
        }

        // Class A unconfirmed message sent, TX_DONE event will be sent to
        // application when RX2 windows is elapsed, i.e., in process_reception_timeout()
        _ctrl_flags &= ~TX_ONGOING_FLAG;
        _ctrl_flags |= TX_DONE_FLAG;

        // In Class C, reception timeout never happens, so we handle the state
        // progression here
        if (_loramac.get_device_class() == CLASS_C) {
            _loramac.post_process_mcps_req();
            state_controller(DEVICE_STATE_STATUS_CHECK);
            state_machine_run_to_completion();
        }
    }
}

void LoRaWANStack::process_reception(const uint8_t* const payload, uint16_t size,
                                     int16_t rssi, int8_t snr)
{
    _device_current_state = DEVICE_STATE_RECEIVING;
    _ctrl_flags &= ~MSG_RECVD_FLAG;

    _loramac.on_radio_rx_done(payload, size, rssi, snr);

    if (_loramac.get_mlme_confirmation()->pending) {
        _loramac.post_process_mlme_request();
        mlme_confirm_handler();
    }

    if (_loramac.nwk_joined()) {
        if (_loramac.get_mcps_confirmation()->req_type == MCPS_CONFIRMED) {
            // if ack was not received, we will try retransmission after
            // ACK_TIMEOUT. handle_data_frame() already disables ACK_TIMEOUT timer
            // if ack was received
            if (_loramac.get_mcps_indication()->is_ack_recvd) {
                tr_debug("Ack=OK, NbTrials=%d", _loramac.get_mcps_confirmation()->nb_retries);
                _loramac.post_process_mcps_req();
                _ctrl_flags |= TX_DONE_FLAG;
                state_controller(DEVICE_STATE_STATUS_CHECK);
            }
        } else {
            // handle UNCONFIRMED, PROPRIETARY case here, RX slots were turned off due to
            // valid packet reception, so we generate a TX_DONE event
            _loramac.post_process_mcps_req();
            _ctrl_flags |= TX_DONE_FLAG;
            state_controller(DEVICE_STATE_STATUS_CHECK);
        }

        // handle any pending MCPS indication
        if (_loramac.get_mcps_indication()->pending) {
            _loramac.post_process_mcps_ind();
            _ctrl_flags |= MSG_RECVD_FLAG;
            state_controller(DEVICE_STATE_STATUS_CHECK);
        }

        // change the state only if a TX cycle completes for Class A
        // For class C it's not needed as it will already be in receiving
        // state, no matter if the TX cycle completed or not.
        if (!(_ctrl_flags & TX_ONGOING_FLAG)) {
            // we are done here, update the state
              state_machine_run_to_completion();
        }

        if (_loramac.get_mlme_indication()->pending) {
            tr_debug("MLME Indication pending");
            _loramac.post_process_mlme_ind();
            tr_debug("Automatic uplink requested");
            mlme_indication_handler();
        }
    }

    _ready_for_rx = true;
}

void LoRaWANStack::process_reception_timeout(bool is_timeout)
{
    // when is_timeout == false, a CRC error took place in the received frame
    // we treat that erroneous frame as no frame received at all, hence handle
    // it exactly as we would handle timeout
    rx_slot_t slot = _loramac.on_radio_rx_timeout(is_timeout);

    if (slot == RX_SLOT_WIN_2 && !_loramac.nwk_joined()) {
        state_controller(DEVICE_STATE_JOINING);
        return;
    }

    /**
     * LoRaWAN Specification 1.0.2. Section 3.3.6
     * Main point:
     *     We indicate successful transmission
     * of UNCONFIRMED message after RX windows are done with.
     *     For a CONFIRMED message, it means that we have not received
     * ack (actually nothing was received), and we should retransmit if we can.
     */
    if (slot == RX_SLOT_WIN_2) {
        _loramac.post_process_mcps_req();

        if (_loramac.get_mcps_confirmation()->req_type == MCPS_CONFIRMED
                && _loramac.continue_sending_process()) {
            return;
        }

        state_controller(DEVICE_STATE_STATUS_CHECK);
        state_machine_run_to_completion();
    }
}

/*****************************************************************************
 * Private methods                                                           *
 ****************************************************************************/
bool LoRaWANStack::is_port_valid(const uint8_t port, bool allow_port_0)
{
    //Application should not use reserved and illegal port numbers.
    if (port == 0) {
        return allow_port_0;
    } else {
        return true;
    }
}

lorawan_status_t LoRaWANStack::set_application_port(const uint8_t port, bool allow_port_0)
{
    if (is_port_valid(port, allow_port_0)) {
        _app_port = port;
        return LORAWAN_STATUS_OK;
    }

    return LORAWAN_STATUS_PORT_INVALID;
}

void LoRaWANStack::state_machine_run_to_completion()
{
    if (_loramac.get_device_class() == CLASS_C) {
        _device_current_state = DEVICE_STATE_RECEIVING;
        return;
    }

    _device_current_state = DEVICE_STATE_IDLE;
}

void LoRaWANStack::send_event_to_application(const lorawan_event_t event) const
{
    if (_callbacks.events) {
        const int ret = _queue->call(_callbacks.events, event);
        MBED_ASSERT(ret != 0);
        (void)ret;
    }
}

void LoRaWANStack::send_automatic_uplink_message(const uint8_t port)
{
    const int16_t ret = handle_tx(port, NULL, 0, MSG_CONFIRMED_FLAG, true, true);
    if (ret < 0) {
        send_event_to_application(AUTOMATIC_UPLINK_ERROR);
    }
}

int LoRaWANStack::convert_to_msg_flag(const mcps_type_t type)
{
    int msg_flag = MSG_UNCONFIRMED_FLAG;
    switch (type) {
        case MCPS_UNCONFIRMED:
            msg_flag = MSG_UNCONFIRMED_FLAG;
            break;

        case MCPS_CONFIRMED:
            msg_flag = MSG_CONFIRMED_FLAG;
            break;

        case MCPS_MULTICAST:
            msg_flag = MSG_MULTICAST_FLAG;
            break;

        case MCPS_PROPRIETARY:
            msg_flag = MSG_PROPRIETARY_FLAG;
            break;

        default:
            tr_error("Unknown message type!");
            MBED_ASSERT(0);
    }

    return msg_flag;
}

lorawan_status_t LoRaWANStack::handle_connect(bool is_otaa)
{
    if (is_otaa) {
        tr_debug("Initiating OTAA");

        // In 1.0.2 spec, counters are always set to zero for new connection.
        // This section is common for both normal and
        // connection restore at this moment. Will change in future with 1.1 support.
        _lw_session.downlink_counter = 0;
        _lw_session.uplink_counter = 0;
        _ctrl_flags |= USING_OTAA_FLAG;
    } else {
        // If current state is SHUTDOWN, device may be trying to re-establish
        // communication. In case of ABP specification is meddled about frame counters.
        // It says to reset counters to zero but there is no mechanism to tell the
        // network server that the device was disconnected or restarted.
        // At the moment, this implementation does not support a non-volatile
        // memory storage.
        //_lw_session.downlink_counter; //Get from NVM
        //_lw_session.uplink_counter; //Get from NVM

        tr_debug("Initiating ABP");
        tr_debug("Frame Counters. UpCnt=%lu, DownCnt=%lu",
                 _lw_session.uplink_counter, _lw_session.downlink_counter);
        _ctrl_flags &= ~USING_OTAA_FLAG;
    }

    return state_controller(DEVICE_STATE_CONNECTING);
}

void LoRaWANStack::mlme_indication_handler()
{
    if (_loramac.get_mlme_indication()->indication_type == MLME_SCHEDULE_UPLINK) {
        // The MAC signals that we shall provide an uplink as soon as possible
#if MBED_CONF_LORA_AUTOMATIC_UPLINK_MESSAGE
        _automatic_uplink_ongoing = true;
        tr_debug("mlme indication: sending empty uplink to port 0 to acknowledge MAC commands...");
        send_automatic_uplink_message(0);
#else

        send_event_to_application(UPLINK_REQUIRED);
#endif
        return;
    }

    tr_error("Unknown MLME Indication type.");
}

void LoRaWANStack::mlme_confirm_handler()
{
    if (_loramac.get_mlme_confirmation()->req_type == MLME_LINK_CHECK) {
        if (_loramac.get_mlme_confirmation()->status == LORAMAC_EVENT_INFO_STATUS_OK) {
#if defined(LORAWAN_COMPLIANCE_TEST)
            if (_compliance_test.running == true) {
                _compliance_test.link_check = true;
                _compliance_test.demod_margin = _loramac.get_mlme_confirmation()->demod_margin;
                _compliance_test.nb_gateways = _loramac.get_mlme_confirmation()->nb_gateways;
            } else
#endif
            {
                if (_callbacks.link_check_resp) {
                    const int ret = _queue->call(_callbacks.link_check_resp,
                                                 _loramac.get_mlme_confirmation()->demod_margin,
                                                 _loramac.get_mlme_confirmation()->nb_gateways);
                    MBED_ASSERT(ret != 0);
                    (void)ret;
                }
            }
        }
    } else if (_loramac.get_mlme_confirmation()->req_type == MLME_JOIN) {
        if (_loramac.get_mlme_confirmation()->status == LORAMAC_EVENT_INFO_STATUS_OK) {
            state_controller(DEVICE_STATE_CONNECTED);
        } else {
            tr_error("Joining error: %d", _loramac.get_mlme_confirmation()->status);
            _device_current_state = DEVICE_STATE_AWAITING_JOIN_ACCEPT;
            state_controller(DEVICE_STATE_JOINING);
        }
    }
}

void LoRaWANStack::mcps_confirm_handler()
{
    // success case
    if (_loramac.get_mcps_confirmation()->status == LORAMAC_EVENT_INFO_STATUS_OK) {
        _lw_session.uplink_counter = _loramac.get_mcps_confirmation()->ul_frame_counter;
        send_event_to_application(TX_DONE);
        return;
    }

    // failure case
    tr_error("mcps_confirmation: Error code = %d", _loramac.get_mcps_confirmation()->status);

    if (_loramac.get_mcps_confirmation()->status == LORAMAC_EVENT_INFO_STATUS_TX_TIMEOUT) {
        send_event_to_application(TX_TIMEOUT);
        return;
    }

    // if no ack was received, send TX_ERROR
    send_event_to_application(TX_ERROR);
}

void LoRaWANStack::mcps_indication_handler()
{
    const loramac_mcps_indication_t *mcps_indication = _loramac.get_mcps_indication();
    if (mcps_indication->status != LORAMAC_EVENT_INFO_STATUS_OK) {
        tr_error("RX_ERROR: mcps_indication status = %d", mcps_indication->status);
        send_event_to_application(RX_ERROR);
        return;
    }

    _lw_session.downlink_counter = mcps_indication->dl_frame_counter;

#if defined(LORAWAN_COMPLIANCE_TEST)
    if (_compliance_test.running == true) {
        _compliance_test.downlink_counter++;
    }
#endif

    if (mcps_indication->port == 224) {
#if defined(LORAWAN_COMPLIANCE_TEST)
        tr_debug("Compliance test command received.");
        compliance_test_handler(mcps_indication);
#else
        tr_info("Compliance test disabled.");
#endif
    } else {
        if (mcps_indication->is_data_recvd) {
            // Valid message arrived.
            _rx_msg.type = LORAMAC_RX_MCPS_INDICATION;
            _rx_msg.msg.mcps_indication.buffer_size = mcps_indication->buffer_size;
            _rx_msg.msg.mcps_indication.port = mcps_indication->port;
            _rx_msg.msg.mcps_indication.buffer = mcps_indication->buffer;
            _rx_msg.msg.mcps_indication.type = mcps_indication->type;

            // Notify application about received frame..
            tr_debug("Packet Received %d bytes",
                     _rx_msg.msg.mcps_indication.buffer_size);
            _rx_msg.receive_ready = true;
            send_event_to_application(RX_DONE);
        }

        /*
         * If fPending bit is set we try to generate an empty packet
         * with CONFIRMED flag set. We always set a CONFIRMED flag so
         * that we could retry a certain number of times if the uplink
         * failed for some reason
         * or
         * Class C and node received a confirmed message so we need to
         * send an empty packet to acknowledge the message.
         * This scenario is unspecified by LoRaWAN 1.0.2 specification,
         * but version 1.1.0 says that network SHALL not send any new
         * confirmed messages until ack has been sent
         */
        if ((_loramac.get_device_class() != CLASS_C && mcps_indication->fpending_status)
                ||
            (_loramac.get_device_class() == CLASS_C && mcps_indication->type == MCPS_CONFIRMED)) {
#if (MBED_CONF_LORA_AUTOMATIC_UPLINK_MESSAGE)
            tr_debug("Sending empty uplink message...");
            _automatic_uplink_ongoing = true;
            send_automatic_uplink_message(mcps_indication->port);
#else
            send_event_to_application(UPLINK_REQUIRED);
#endif
        }
    }
}

lorawan_status_t LoRaWANStack::state_controller(device_states_t new_state)
{
    lorawan_status_t status = LORAWAN_STATUS_OK;

    switch (new_state) {
        case DEVICE_STATE_IDLE:
            process_idle_state(status);
            break;
        case DEVICE_STATE_CONNECTING:
            process_connecting_state(status);
            break;
        case DEVICE_STATE_JOINING:
            process_joining_state(status);
            break;
        case DEVICE_STATE_CONNECTED:
            process_connected_state();
            break;
        case DEVICE_STATE_SCHEDULING:
            process_scheduling_state(status);
            break;
        case DEVICE_STATE_STATUS_CHECK:
            process_status_check_state();
            break;
        case DEVICE_STATE_SHUTDOWN:
            process_shutdown_state(status);
            break;
        default:
            tr_debug("state_controller: Unknown state!");
            status = LORAWAN_STATUS_SERVICE_UNKNOWN;
            break;
    }

    return status;
}

void LoRaWANStack::process_shutdown_state(lorawan_status_t& op_status)
{
    /**
     * Remove channels
     * Radio will be put to sleep by the APIs underneath
     */
    drop_channel_list();
    _loramac.disconnect();
    _lw_session.active = false;
    _device_current_state = DEVICE_STATE_SHUTDOWN;
    op_status = LORAWAN_STATUS_DEVICE_OFF;
    _ctrl_flags &= ~CONNECTED_FLAG;
    send_event_to_application(DISCONNECTED);
}

void LoRaWANStack::process_status_check_state()
{
    if (_device_current_state == DEVICE_STATE_SENDING ||
        _device_current_state == DEVICE_STATE_AWAITING_ACK) {
        // this happens after RX2 slot is exhausted
        // we may or may not have a successful UNCONFIRMED transmission
        // here. In CONFIRMED case this block is invoked only
        // when the MAX number of retries are exhausted, i.e., only error
        // case will fall here.
        _ctrl_flags &= ~TX_DONE_FLAG;
        _ctrl_flags &= ~TX_ONGOING_FLAG;
        _loramac.set_tx_ongoing(false);
        _loramac.reset_ongoing_tx();
        mcps_confirm_handler();

    } else if (_device_current_state == DEVICE_STATE_RECEIVING) {

        if (_ctrl_flags & TX_DONE_FLAG) {
            // for CONFIRMED case, ack validity is already checked
            _ctrl_flags &= ~TX_DONE_FLAG;
            _ctrl_flags &= ~TX_ONGOING_FLAG;
            _loramac.set_tx_ongoing(false);
            _loramac.reset_ongoing_tx();
            // if an automatic uplink is ongoing, we should not send a TX_DONE
            // event to application
            if (_automatic_uplink_ongoing) {
                _automatic_uplink_ongoing = false;
            } else {
                mcps_confirm_handler();
            }
        }

        // handle any received data and send event accordingly
        if (_ctrl_flags & MSG_RECVD_FLAG) {
            _ctrl_flags &= ~MSG_RECVD_FLAG;
            mcps_indication_handler();
        }
    }
}

void LoRaWANStack::process_scheduling_state(lorawan_status_t& op_status)
{
    if (_device_current_state != DEVICE_STATE_IDLE) {
        if (_device_current_state != DEVICE_STATE_RECEIVING
            && _loramac.get_device_class() != CLASS_C) {
            op_status = LORAWAN_STATUS_BUSY;
            return;
        }
    }

    op_status = _loramac.send_ongoing_tx();
    if (op_status == LORAWAN_STATUS_OK) {
        _ctrl_flags |= TX_ONGOING_FLAG;
        _ctrl_flags &= ~TX_DONE_FLAG;
        _loramac.set_tx_ongoing(true);
        _device_current_state = DEVICE_STATE_SENDING;
    }
}

void LoRaWANStack::process_joining_state(lorawan_status_t& op_status)
{
    if (_device_current_state == DEVICE_STATE_CONNECTING) {
        _device_current_state = DEVICE_STATE_JOINING;
        tr_debug("Sending Join Request ...");
        op_status = _loramac.join(true);
        return;
    }

    if (_device_current_state == DEVICE_STATE_AWAITING_JOIN_ACCEPT) {
        _device_current_state = DEVICE_STATE_JOINING;
        // retry join
        bool can_continue = _loramac.continue_joining_process();

        if (!can_continue) {
            send_event_to_application(JOIN_FAILURE);
            _device_current_state = DEVICE_STATE_IDLE;
            return;
        }
    }
}

void LoRaWANStack::process_connected_state()
{
    if (_ctrl_flags & USING_OTAA_FLAG) {
        tr_debug("OTAA Connection OK!");
    }

    _lw_session.active = true;
    send_event_to_application(CONNECTED);
    _ctrl_flags |= CONNECTED_FLAG;

    _device_current_state = DEVICE_STATE_IDLE;
}

void LoRaWANStack::process_connecting_state(lorawan_status_t& op_status)
{
    if (_device_current_state != DEVICE_STATE_IDLE
        &&
        _device_current_state != DEVICE_STATE_SHUTDOWN) {
        op_status = LORAWAN_STATUS_BUSY;
        return;
    }

    if (_ctrl_flags & CONNECTED_FLAG) {
        tr_debug("Already connected");
        op_status = LORAWAN_STATUS_OK;
        return;
    }

    _device_current_state = DEVICE_STATE_CONNECTING;

    if (_ctrl_flags & USING_OTAA_FLAG) {
        process_joining_state(op_status);
        return;
    }

    op_status = _loramac.join(false);
    tr_debug("ABP connection OK.");
    process_connected_state();
}

void LoRaWANStack::process_idle_state(lorawan_status_t& op_status)
{
    if (_device_current_state == DEVICE_STATE_NOT_INITIALIZED) {
        _device_current_state = DEVICE_STATE_IDLE;
        process_uninitialized_state(op_status);
        return;
    }

    _device_current_state = DEVICE_STATE_IDLE;
    op_status = LORAWAN_STATUS_OK;
}

void LoRaWANStack::process_uninitialized_state(lorawan_status_t& op_status)
{
    op_status = _loramac.initialize(_queue);

    if (op_status == LORAWAN_STATUS_OK) {
        _device_current_state = DEVICE_STATE_IDLE;
    }
}

#if defined(LORAWAN_COMPLIANCE_TEST)

lorawan_status_t LoRaWANStack::send_compliance_test_frame_to_mac()
{
    loramac_compliance_test_req_t test_req;

    //TODO: What if the port is not 224 ???
    if (_compliance_test.app_port == 224) {
        // Clear any normal message stuff before compliance test.
        memset(&test_req, 0, sizeof(test_req));

        if (_compliance_test.link_check == true) {
            _compliance_test.link_check = false;
            _compliance_test.state = 1;
            test_req.f_buffer_size = 3;
            test_req.f_buffer[0] = 5;
            test_req.f_buffer[1] = _compliance_test.demod_margin;
            test_req.f_buffer[2] = _compliance_test.nb_gateways;
        } else {
            switch (_compliance_test.state) {
            case 4:
                _compliance_test.state = 1;
                test_req.f_buffer_size = _compliance_test.app_data_size;
                test_req.f_buffer[0] = _compliance_test.app_data_buffer[0];
                for(uint8_t i = 1; i < MIN(_compliance_test.app_data_size, MBED_CONF_LORA_TX_MAX_SIZE); ++i) {
                    test_req.f_buffer[i] = _compliance_test.app_data_buffer[i];
                }
                break;
            case 1:
                test_req.f_buffer_size = 2;
                test_req.f_buffer[0] = _compliance_test.downlink_counter >> 8;
                test_req.f_buffer[1] = _compliance_test.downlink_counter;
                break;
            }
        }
    }

    //TODO: If port is not 224, this might not work!
    //Is there a test case where same _tx_msg's buffer would be used, when port is not 224???
    if (!_compliance_test.is_tx_confirmed) {
        test_req.type = MCPS_UNCONFIRMED;
        test_req.fport = _compliance_test.app_port;
        test_req.nb_trials = 1;
        test_req.data_rate = _loramac.get_default_tx_datarate();

        tr_info("Transmit unconfirmed compliance test frame %d bytes.", test_req.f_buffer_size);

        for (uint8_t i = 0; i < test_req.f_buffer_size; ++i) {
            tr_info("Byte %d, data is 0x%x", i+1, ((uint8_t*)test_req.f_buffer)[i]);
        }
    } else if (_compliance_test.is_tx_confirmed) {
        test_req.type = MCPS_CONFIRMED;
        test_req.fport = _compliance_test.app_port;
        test_req.nb_trials = _num_retry;
        test_req.data_rate = _loramac.get_default_tx_datarate();

        tr_info("Transmit confirmed compliance test frame %d bytes.", test_req.f_buffer_size);

        for (uint8_t i = 0; i < test_req.f_buffer_size; ++i) {
            tr_info("Byte %d, data is 0x%x", i+1, ((uint8_t*)test_req.f_buffer)[i]);
        }
    } else {
        return LORAWAN_STATUS_SERVICE_UNKNOWN;
    }

    return _loramac.test_request(&test_req);
}

void LoRaWANStack::compliance_test_handler(loramac_mcps_indication_t *mcps_indication)
{
    if (_compliance_test.running == false) {
        // Check compliance test enable command (i)
        if ((mcps_indication->buffer_size == 4) &&
            (mcps_indication->buffer[0] == 0x01) &&
            (mcps_indication->buffer[1] == 0x01) &&
            (mcps_indication->buffer[2] == 0x01) &&
            (mcps_indication->buffer[3] == 0x01)) {
            _compliance_test.is_tx_confirmed = false;
            _compliance_test.app_port = 224;
            _compliance_test.app_data_size = 2;
            _compliance_test.downlink_counter = 0;
            _compliance_test.link_check = false;
            _compliance_test.demod_margin = 0;
            _compliance_test.nb_gateways = 0;
            _compliance_test.running = true;
            _compliance_test.state = 1;

            _loramac.enable_adaptive_datarate(true);

#if MBED_CONF_LORA_PHY      == 0
            _loramac.LoRaMacTestSetDutyCycleOn(false);
#endif
            //5000ms
            _loramac.LoRaMacSetTxTimer(5000);

            //TODO: Should we call lora_state_machine here instead of just setting the state?
            _device_current_state = DEVICE_STATE_COMPLIANCE_TEST;
//            lora_state_machine(DEVICE_STATE_COMPLIANCE_TEST);
            tr_debug("Compliance test activated.");
        }
    } else {
        _compliance_test.state = mcps_indication->buffer[0];
        switch (_compliance_test.state) {
        case 0: // Check compliance test disable command (ii)
            _compliance_test.is_tx_confirmed = true;
            _compliance_test.app_port = MBED_CONF_LORA_APP_PORT;
            _compliance_test.app_data_size = LORAWAN_COMPLIANCE_TEST_DATA_SIZE;
            _compliance_test.downlink_counter = 0;
            _compliance_test.running = false;

            _loramac.enable_adaptive_datarate(MBED_CONF_LORA_ADR_ON);

#if MBED_CONF_LORA_PHY      == 0
            _loramac.LoRaMacTestSetDutyCycleOn(MBED_CONF_LORA_DUTY_CYCLE_ON);
#endif
            // Go to idle state after compliance test mode.
            tr_debug("Compliance test disabled.");
            _loramac.LoRaMacStopTxTimer();

            // Clear any compliance test message stuff before going back to normal operation.
            _loramac.reset_ongoing_tx();
            lora_state_machine(DEVICE_STATE_IDLE);
            break;
        case 1: // (iii, iv)
            _compliance_test.app_data_size = 2;
            break;
        case 2: // Enable confirmed messages (v)
            _compliance_test.is_tx_confirmed = true;
            _compliance_test.state = 1;
            break;
        case 3:  // Disable confirmed messages (vi)
            _compliance_test.is_tx_confirmed = false;
            _compliance_test.state = 1;
            break;
        case 4: // (vii)
            _compliance_test.app_data_size = mcps_indication->buffer_size;

            _compliance_test.app_data_buffer[0] = 4;
            for(uint8_t i = 1; i < MIN(_compliance_test.app_data_size, LORAMAC_PHY_MAXPAYLOAD); ++i) {
                _compliance_test.app_data_buffer[i] = mcps_indication->buffer[i] + 1;
            }

            send_compliance_test_frame_to_mac();
            break;
        case 5: // (viii)
            _loramac.setup_link_check_request();
            break;
        case 6: // (ix)
            // Disable TestMode and revert back to normal operation
            _compliance_test.is_tx_confirmed = true;
            _compliance_test.app_port = MBED_CONF_LORA_APP_PORT;
            _compliance_test.app_data_size = LORAWAN_COMPLIANCE_TEST_DATA_SIZE;
            _compliance_test.downlink_counter = 0;
            _compliance_test.running = false;

            _loramac.enable_adaptive_datarate(MBED_CONF_LORA_ADR_ON);

#if MBED_CONF_LORA_PHY      == 0
            _loramac.LoRaMacTestSetDutyCycleOn(MBED_CONF_LORA_DUTY_CYCLE_ON);
#endif
            _loramac.join(true);
            break;
        case 7: // (x)
            if (mcps_indication->buffer_size == 3) {
                loramac_mlme_req_t mlme_req;
                mlme_req.type = MLME_TXCW;
                mlme_req.cw_tx_mode.timeout = (uint16_t)((mcps_indication->buffer[1] << 8) | mcps_indication->buffer[2]);
                _loramac.mlme_request(&mlme_req);
            } else if (mcps_indication->buffer_size == 7) {
                loramac_mlme_req_t mlme_req;
                mlme_req.type = MLME_TXCW_1;
                mlme_req.cw_tx_mode.timeout = (uint16_t)((mcps_indication->buffer[1] << 8) | mcps_indication->buffer[2]);
                mlme_req.cw_tx_mode.frequency = (uint32_t)((mcps_indication->buffer[3] << 16) | (mcps_indication->buffer[4] << 8)
                        | mcps_indication->buffer[5]) * 100;
                mlme_req.cw_tx_mode.power = mcps_indication->buffer[6];
                _loramac.mlme_request(&mlme_req);
            }
            _compliance_test.state = 1;
            break;
        }
    }
}
#endif