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osd-contiki/core/net/mac/tsch/tsch-slot-operation.c

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Added IEEE 802.15.4e TSCH (TimeSlotted Channel Hopping) MAC layer
2015-09-21 22:01:01 +02:00
/*
* Copyright (c) 2015, SICS Swedish ICT.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
*/
/**
* \file
* TSCH slot operation implementation, running from interrupt.
* \author
* Simon Duquennoy <simonduq@sics.se>
* Beshr Al Nahas <beshr@sics.se>
*
*/
#include "contiki.h"
#include "dev/radio.h"
#include "net/netstack.h"
#include "net/packetbuf.h"
#include "net/queuebuf.h"
#include "net/mac/framer-802154.h"
#include "net/mac/tsch/tsch.h"
#include "net/mac/tsch/tsch-slot-operation.h"
#include "net/mac/tsch/tsch-queue.h"
#include "net/mac/tsch/tsch-private.h"
#include "net/mac/tsch/tsch-log.h"
#include "net/mac/tsch/tsch-packet.h"
#include "net/mac/tsch/tsch-security.h"
#if TSCH_LOG_LEVEL >= 1
#define DEBUG DEBUG_PRINT
#else /* TSCH_LOG_LEVEL */
#define DEBUG DEBUG_NONE
#endif /* TSCH_LOG_LEVEL */
#include "net/ip/uip-debug.h"
/* TSCH debug macros, i.e. to set LEDs or GPIOs on various TSCH
* timeslot events */
#ifndef TSCH_DEBUG_INIT
#define TSCH_DEBUG_INIT()
#endif
#ifndef TSCH_DEBUG_INTERRUPT
#define TSCH_DEBUG_INTERRUPT()
#endif
#ifndef TSCH_DEBUG_RX_EVENT
#define TSCH_DEBUG_RX_EVENT()
#endif
#ifndef TSCH_DEBUG_TX_EVENT
#define TSCH_DEBUG_TX_EVENT()
#endif
#ifndef TSCH_DEBUG_SLOT_START
#define TSCH_DEBUG_SLOT_START()
#endif
#ifndef TSCH_DEBUG_SLOT_END
#define TSCH_DEBUG_SLOT_END()
#endif
/* Check if TSCH_MAX_INCOMING_PACKETS is power of two */
#if (TSCH_MAX_INCOMING_PACKETS & (TSCH_MAX_INCOMING_PACKETS - 1)) != 0
#error TSCH_MAX_INCOMING_PACKETS must be power of two
#endif
/* Check if TSCH_DEQUEUED_ARRAY_SIZE is power of two and greater or equal to QUEUEBUF_NUM */
#if TSCH_DEQUEUED_ARRAY_SIZE < QUEUEBUF_NUM
#error TSCH_DEQUEUED_ARRAY_SIZE must be greater or equal to QUEUEBUF_NUM
#endif
#if (TSCH_DEQUEUED_ARRAY_SIZE & (TSCH_DEQUEUED_ARRAY_SIZE - 1)) != 0
#error TSCH_QUEUE_NUM_PER_NEIGHBOR must be power of two
#endif
/* Truncate received drift correction information to maximum half
* of the guard time (one fourth of TSCH_DEFAULT_TS_RX_WAIT) */
#define SYNC_IE_BOUND ((int32_t)US_TO_RTIMERTICKS(TSCH_DEFAULT_TS_RX_WAIT / 4))
/* By default: check that rtimer runs at >=32kHz and use a guard time of 10us */
#if RTIMER_SECOND < (32 * 1024)
#error "TSCH: RTIMER_SECOND < (32 * 1024)"
#endif
#if RTIMER_SECOND >= 200000
#define RTIMER_GUARD (RTIMER_SECOND / 100000)
#else
#define RTIMER_GUARD 2u
#endif
/* A ringbuf storing outgoing packets after they were dequeued.
* Will be processed layer by tsch_tx_process_pending */
struct ringbufindex dequeued_ringbuf;
struct tsch_packet *dequeued_array[TSCH_DEQUEUED_ARRAY_SIZE];
/* A ringbuf storing incoming packets.
* Will be processed layer by tsch_rx_process_pending */
struct ringbufindex input_ringbuf;
struct input_packet input_array[TSCH_MAX_INCOMING_PACKETS];
/* Last time we received Sync-IE (ACK or data packet from a time source) */
static struct asn_t last_sync_asn;
/* A global lock for manipulating data structures safely from outside of interrupt */
static volatile int tsch_locked = 0;
/* As long as this is set, skip all slot operation */
static volatile int tsch_lock_requested = 0;
/* Last estimated drift in RTIMER ticks
* (Sky: 1 tick ~= 30.52 uSec) */
static int32_t drift_correction = 0;
static struct tsch_neighbor *drift_neighbor = NULL;
/* Used from tsch_slot_operation and sub-protothreads */
static rtimer_clock_t volatile current_slot_start;
/* Are we currently inside a slot? */
static volatile int tsch_in_slot_operation = 0;
/* Info about the link, packet and neighbor of
* the current (or next) slot */
struct tsch_link *current_link = NULL;
/* A backup link with Rx flag, overlapping with current_link.
* If the current link is Tx-only and the Tx queue
* is empty while executing the link, fallback to the backup link. */
static struct tsch_link *backup_link = NULL;
static struct tsch_packet *current_packet = NULL;
static struct tsch_neighbor *current_neighbor = NULL;
/* Protothread for association */
PT_THREAD(tsch_scan(struct pt *pt));
/* Protothread for slot operation, called from rtimer interrupt
* and scheduled from tsch_schedule_slot_operation */
static PT_THREAD(tsch_slot_operation(struct rtimer *t, void *ptr));
static struct pt slot_operation_pt;
/* Sub-protothreads of tsch_slot_operation */
static PT_THREAD(tsch_tx_slot(struct pt *pt, struct rtimer *t));
static PT_THREAD(tsch_rx_slot(struct pt *pt, struct rtimer *t));
/*---------------------------------------------------------------------------*/
/* TSCH locking system. TSCH is locked during slot operations */
/* Is TSCH locked? */
int
tsch_is_locked(void)
{
return tsch_locked;
}
/* Lock TSCH (no slot operation) */
int
tsch_get_lock(void)
{
if(!tsch_locked) {
rtimer_clock_t busy_wait_time;
int busy_wait = 0; /* Flag used for logging purposes */
/* Make sure no new slot operation will start */
tsch_lock_requested = 1;
/* Wait for the end of current slot operation. */
if(tsch_in_slot_operation) {
busy_wait = 1;
busy_wait_time = RTIMER_NOW();
while(tsch_in_slot_operation);
busy_wait_time = RTIMER_NOW() - busy_wait_time;
}
if(!tsch_locked) {
/* Take the lock if it is free */
tsch_locked = 1;
tsch_lock_requested = 0;
if(busy_wait) {
/* Issue a log whenever we had to busy wait until getting the lock */
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!get lock delay %u", busy_wait_time);
);
}
return 1;
}
}
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!failed to lock");
);
return 0;
}
/* Release TSCH lock */
void
tsch_release_lock(void)
{
tsch_locked = 0;
}
/*---------------------------------------------------------------------------*/
/* Channel hopping utility functions */
/* Return channel from ASN and channel offset */
uint8_t
tsch_calculate_channel(struct asn_t *asn, uint8_t channel_offset)
{
uint16_t index_of_0 = ASN_MOD(*asn, tsch_hopping_sequence_length);
uint16_t index_of_offset = (index_of_0 + channel_offset) % tsch_hopping_sequence_length.val;
return tsch_hopping_sequence[index_of_offset];
}
/*---------------------------------------------------------------------------*/
/* Timing utility functions */
/* Checks if the current time has passed a ref time + offset. Assumes
* a single overflow and ref time prior to now. */
static uint8_t
check_timer_miss(rtimer_clock_t ref_time, rtimer_clock_t offset, rtimer_clock_t now)
{
rtimer_clock_t target = ref_time + offset;
int now_has_overflowed = now < ref_time;
int target_has_overflowed = target < ref_time;
if(now_has_overflowed == target_has_overflowed) {
/* Both or none have overflowed, just compare now to the target */
return target <= now;
} else {
/* Either now or target of overflowed.
* If it is now, then it has passed the target.
* If it is target, then we haven't reached it yet.
* */
return now_has_overflowed;
}
}
/*---------------------------------------------------------------------------*/
/* Schedule a wakeup at a specified offset from a reference time.
* Provides basic protection against missed deadlines and timer overflows
* A non-zero return value signals to tsch_slot_operation a missed deadline.
* If conditional: schedule only if the deadline is not missed, else busy wait.
* If not conditional: schedule regardless of deadline miss. */
static uint8_t
tsch_schedule_slot_operation(struct rtimer *tm, rtimer_clock_t ref_time, rtimer_clock_t offset, int conditional, const char *str)
{
rtimer_clock_t now = RTIMER_NOW();
int r;
int missed = check_timer_miss(ref_time, offset - RTIMER_GUARD, now);
if(missed) {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!dl-miss-%d %s %d %d",
conditional, str,
(int)(now-ref_time), (int)offset);
);
if(conditional) {
BUSYWAIT_UNTIL_ABS(0, ref_time, offset);
return 0;
}
}
ref_time += offset;
r = rtimer_set(tm, ref_time, 1, (void (*)(struct rtimer *, void *))tsch_slot_operation, NULL);
if(r != RTIMER_OK) {
return 0;
}
return 1;
}
/*---------------------------------------------------------------------------*/
/* Schedule slot operation conditionally, and YIELD if success only */
#define TSCH_SCHEDULE_AND_YIELD(pt, tm, ref_time, offset, str) \
do { \
if(tsch_schedule_slot_operation(tm, ref_time, offset, 1, str)) { \
PT_YIELD(pt); \
} \
} while(0);
/*---------------------------------------------------------------------------*/
/* Get EB, broadcast or unicast packet to be sent, and target neighbor. */
static struct tsch_packet *
get_packet_and_neighbor_for_link(struct tsch_link *link, struct tsch_neighbor **target_neighbor)
{
struct tsch_packet *p = NULL;
struct tsch_neighbor *n = NULL;
/* Is this a Tx link? */
if(link->link_options & LINK_OPTION_TX) {
/* is it for advertisement of EB? */
if(link->link_type == LINK_TYPE_ADVERTISING || link->link_type == LINK_TYPE_ADVERTISING_ONLY) {
/* fetch EB packets */
n = n_eb;
p = tsch_queue_get_packet_for_nbr(n, link);
}
if(link->link_type != LINK_TYPE_ADVERTISING_ONLY) {
/* NORMAL link or no EB to send, pick a data packet */
if(p == NULL) {
/* Get neighbor queue associated to the link and get packet from it */
n = tsch_queue_get_nbr(&link->addr);
p = tsch_queue_get_packet_for_nbr(n, link);
/* if it is a broadcast slot and there were no broadcast packets, pick any unicast packet */
if(p == NULL && n == n_broadcast) {
p = tsch_queue_get_unicast_packet_for_any(&n, link);
}
}
}
}
/* return nbr (by reference) */
if(target_neighbor != NULL) {
*target_neighbor = n;
}
return p;
}
/*---------------------------------------------------------------------------*/
/* Post TX: Update neighbor state after a transmission */
static int
update_neighbor_state(struct tsch_neighbor *n, struct tsch_packet *p,
struct tsch_link *link, uint8_t mac_tx_status)
{
int in_queue = 1;
int is_shared_link = link->link_options & LINK_OPTION_SHARED;
int is_unicast = !n->is_broadcast;
if(mac_tx_status == MAC_TX_OK) {
/* Successful transmission */
tsch_queue_remove_packet_from_queue(n);
in_queue = 0;
/* Update CSMA state in the unicast case */
if(is_unicast) {
if(is_shared_link || tsch_queue_is_empty(n)) {
/* If this is a shared link, reset backoff on success.
* Otherwise, do so only is the queue is empty */
tsch_queue_backoff_reset(n);
}
}
} else {
/* Failed transmission */
if(p->transmissions >= TSCH_MAC_MAX_FRAME_RETRIES + 1) {
/* Drop packet */
tsch_queue_remove_packet_from_queue(n);
in_queue = 0;
}
/* Update CSMA state in the unicast case */
if(is_unicast) {
/* Failures on dedicated (== non-shared) leave the backoff
* window nor exponent unchanged */
if(is_shared_link) {
/* Shared link: increment backoff exponent, pick a new window */
tsch_queue_backoff_inc(n);
}
}
}
return in_queue;
}
/*---------------------------------------------------------------------------*/
static
PT_THREAD(tsch_tx_slot(struct pt *pt, struct rtimer *t))
{
/**
* TX slot:
* 1. Copy packet to radio buffer
* 2. Perform CCA if enabled
* 3. Sleep until it is time to transmit
* 4. Wait for ACK if it is a unicast packet
* 5. Extract drift if we received an E-ACK from a time source neighbor
* 6. Update CSMA parameters according to TX status
* 7. Schedule mac_call_sent_callback
**/
/* tx status */
static uint8_t mac_tx_status;
/* is the packet in its neighbor's queue? */
uint8_t in_queue;
static int dequeued_index;
static int packet_ready = 1;
PT_BEGIN(pt);
TSCH_DEBUG_TX_EVENT();
/* First check if we have space to store a newly dequeued packet (in case of
* successful Tx or Drop) */
dequeued_index = ringbufindex_peek_put(&dequeued_ringbuf);
if(dequeued_index != -1) {
/* is this a data packet? */
static uint8_t is_data;
if(current_packet == NULL || current_packet->qb == NULL) {
mac_tx_status = MAC_TX_ERR_FATAL;
} else {
/* packet payload */
static void *packet;
#if TSCH_SECURITY_ENABLED
/* encrypted payload */
static uint8_t encrypted_packet[TSCH_PACKET_MAX_LEN];
#endif /* TSCH_SECURITY_ENABLED */
/* packet payload length */
static uint8_t packet_len;
/* packet seqno */
static uint8_t seqno;
/* is this a broadcast packet? (wait for ack?) */
static uint8_t is_broadcast;
static rtimer_clock_t tx_start_time;
#if CCA_ENABLED
static uint8_t cca_status;
#endif
/* get payload */
packet = queuebuf_dataptr(current_packet->qb);
packet_len = queuebuf_datalen(current_packet->qb);
/* is this a broadcast packet? (wait for ack?) */
is_broadcast = current_neighbor->is_broadcast;
is_data = ((((uint8_t *)(packet))[0]) & 7) == FRAME802154_DATAFRAME;
/* read seqno from payload */
seqno = ((uint8_t *)(packet))[2];
/* if this is an EB, then update its Sync-IE */
if(current_neighbor == n_eb) {
packet_ready = tsch_packet_update_eb(packet, packet_len, current_packet->tsch_sync_ie_offset);
} else {
packet_ready = 1;
}
#if TSCH_SECURITY_ENABLED
if(tsch_is_pan_secured) {
/* If we are going to encrypt, we need to generate the output in a separate buffer and keep
* the original untouched. This is to allow for future retransmissions. */
int with_encryption = queuebuf_attr(current_packet->qb, PACKETBUF_ATTR_SECURITY_LEVEL) & 0x4;
packet_len += tsch_security_secure_frame(packet, with_encryption ? encrypted_packet : packet, current_packet->header_len,
packet_len - current_packet->header_len, &current_asn);
if(with_encryption) {
packet = encrypted_packet;
}
}
#endif /* TSCH_SECURITY_ENABLED */
/* prepare packet to send: copy to radio buffer */
if(packet_ready && NETSTACK_RADIO.prepare(packet, packet_len) == 0) { /* 0 means success */
static rtimer_clock_t tx_duration;
#if CCA_ENABLED
cca_status = 1;
/* delay before CCA */
TSCH_SCHEDULE_AND_YIELD(pt, t, current_slot_start, TS_CCA_OFFSET, "cca");
TSCH_DEBUG_TX_EVENT();
NETSTACK_RADIO.on();
/* CCA */
BUSYWAIT_UNTIL_ABS(!(cca_status |= NETSTACK_RADIO.channel_clear()),
current_slot_start, TS_CCA_OFFSET + TS_CCA);
TSCH_DEBUG_TX_EVENT();
/* there is not enough time to turn radio off */
/* NETSTACK_RADIO.off(); */
if(cca_status == 0) {
mac_tx_status = MAC_TX_COLLISION;
} else
#endif /* CCA_ENABLED */
{
/* delay before TX */
TSCH_SCHEDULE_AND_YIELD(pt, t, current_slot_start, tsch_timing[tsch_ts_tx_offset] - RADIO_DELAY_BEFORE_TX, "TxBeforeTx");
TSCH_DEBUG_TX_EVENT();
/* send packet already in radio tx buffer */
mac_tx_status = NETSTACK_RADIO.transmit(packet_len);
/* Save tx timestamp */
tx_start_time = current_slot_start + tsch_timing[tsch_ts_tx_offset];
/* calculate TX duration based on sent packet len */
tx_duration = TSCH_PACKET_DURATION(packet_len);
/* limit tx_time to its max value */
tx_duration = MIN(tx_duration, tsch_timing[tsch_ts_max_tx]);
/* turn tadio off -- will turn on again to wait for ACK if needed */
NETSTACK_RADIO.off();
if(mac_tx_status == RADIO_TX_OK) {
if(!is_broadcast) {
uint8_t ackbuf[TSCH_PACKET_MAX_LEN];
int ack_len;
rtimer_clock_t ack_start_time;
int is_time_source;
radio_value_t radio_rx_mode;
struct ieee802154_ies ack_ies;
uint8_t ack_hdrlen;
frame802154_t frame;
/* Entering promiscuous mode so that the radio accepts the enhanced ACK */
NETSTACK_RADIO.get_value(RADIO_PARAM_RX_MODE, &radio_rx_mode);
NETSTACK_RADIO.set_value(RADIO_PARAM_RX_MODE, radio_rx_mode & (~RADIO_RX_MODE_ADDRESS_FILTER));
/* Unicast: wait for ack after tx: sleep until ack time */
TSCH_SCHEDULE_AND_YIELD(pt, t, current_slot_start,
tsch_timing[tsch_ts_tx_offset] + tx_duration + tsch_timing[tsch_ts_rx_ack_delay] - RADIO_DELAY_BEFORE_RX, "TxBeforeAck");
TSCH_DEBUG_TX_EVENT();
NETSTACK_RADIO.on();
/* Wait for ACK to come */
BUSYWAIT_UNTIL_ABS(NETSTACK_RADIO.receiving_packet(),
tx_start_time, tx_duration + tsch_timing[tsch_ts_rx_ack_delay] + tsch_timing[tsch_ts_ack_wait]);
TSCH_DEBUG_TX_EVENT();
ack_start_time = RTIMER_NOW();
/* Wait for ACK to finish */
BUSYWAIT_UNTIL_ABS(!NETSTACK_RADIO.receiving_packet(),
ack_start_time, tsch_timing[tsch_ts_max_ack]);
TSCH_DEBUG_TX_EVENT();
NETSTACK_RADIO.off();
/* Leaving promiscuous mode */
NETSTACK_RADIO.get_value(RADIO_PARAM_RX_MODE, &radio_rx_mode);
NETSTACK_RADIO.set_value(RADIO_PARAM_RX_MODE, radio_rx_mode | RADIO_RX_MODE_ADDRESS_FILTER);
/* Read ack frame */
ack_len = NETSTACK_RADIO.read((void *)ackbuf, sizeof(ackbuf));
is_time_source = 0;
/* The radio driver should return 0 if no valid packets are in the rx buffer */
if(ack_len > 0) {
is_time_source = current_neighbor != NULL && current_neighbor->is_time_source;
if(tsch_packet_parse_eack(ackbuf, ack_len, seqno,
&frame, &ack_ies, &ack_hdrlen) == 0) {
ack_len = 0;
}
#if TSCH_SECURITY_ENABLED
if(ack_len != 0) {
if(!tsch_security_parse_frame(ackbuf, ack_hdrlen, ack_len - ack_hdrlen - tsch_security_mic_len(&frame),
&frame, &current_neighbor->addr, &current_asn)) {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!failed to authenticate ACK"));
ack_len = 0;
}
} else {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!failed to parse ACK"));
}
#endif /* TSCH_SECURITY_ENABLED */
}
if(ack_len != 0) {
if(is_time_source) {
int32_t eack_time_correction = US_TO_RTIMERTICKS(ack_ies.ie_time_correction);
if(eack_time_correction > SYNC_IE_BOUND) {
drift_correction = SYNC_IE_BOUND;
} else if(eack_time_correction < -SYNC_IE_BOUND) {
drift_correction = -SYNC_IE_BOUND;
} else {
drift_correction = eack_time_correction;
}
if(drift_correction != eack_time_correction) {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!truncated dr %d %d", (int)eack_time_correction, (int)drift_correction);
);
}
drift_neighbor = current_neighbor;
/* Keep track of sync time */
last_sync_asn = current_asn;
tsch_schedule_keepalive();
}
mac_tx_status = MAC_TX_OK;
} else {
mac_tx_status = MAC_TX_NOACK;
}
} else {
mac_tx_status = MAC_TX_OK;
}
} else {
mac_tx_status = MAC_TX_ERR;
}
}
}
}
current_packet->transmissions++;
current_packet->ret = mac_tx_status;
/* Post TX: Update neighbor state */
in_queue = update_neighbor_state(current_neighbor, current_packet, current_link, mac_tx_status);
/* The packet was dequeued, add it to dequeued_ringbuf for later processing */
if(in_queue == 0) {
dequeued_array[dequeued_index] = current_packet;
ringbufindex_put(&dequeued_ringbuf);
}
/* Log every tx attempt */
TSCH_LOG_ADD(tsch_log_tx,
log->tx.mac_tx_status = mac_tx_status;
log->tx.num_tx = current_packet->transmissions;
log->tx.datalen = queuebuf_datalen(current_packet->qb);
log->tx.drift = drift_correction;
log->tx.drift_used = drift_neighbor != NULL;
log->tx.is_data = is_data;
log->tx.sec_level = queuebuf_attr(current_packet->qb, PACKETBUF_ATTR_SECURITY_LEVEL);
log->tx.dest = TSCH_LOG_ID_FROM_LINKADDR(queuebuf_addr(current_packet->qb, PACKETBUF_ADDR_RECEIVER));
);
/* Poll process for later processing of packet sent events and logs */
process_poll(&tsch_pending_events_process);
}
TSCH_DEBUG_TX_EVENT();
PT_END(pt);
}
/*---------------------------------------------------------------------------*/
static
PT_THREAD(tsch_rx_slot(struct pt *pt, struct rtimer *t))
{
/**
* RX slot:
* 1. Check if it is used for TIME_KEEPING
* 2. Sleep and wake up just before expected RX time (with a guard time: TS_LONG_GT)
* 3. Check for radio activity for the guard time: TS_LONG_GT
* 4. Prepare and send ACK if needed
* 5. Drift calculated in the ACK callback registered with the radio driver. Use it if receiving from a time source neighbor.
**/
struct tsch_neighbor *n;
static linkaddr_t source_address;
static linkaddr_t destination_address;
static int16_t input_index;
static int input_queue_drop = 0;
PT_BEGIN(pt);
TSCH_DEBUG_RX_EVENT();
input_index = ringbufindex_peek_put(&input_ringbuf);
if(input_index == -1) {
input_queue_drop++;
} else {
static struct input_packet *current_input;
/* Estimated drift based on RX time */
static int32_t estimated_drift;
/* Rx timestamps */
static rtimer_clock_t rx_start_time;
static rtimer_clock_t expected_rx_time;
static rtimer_clock_t packet_duration;
expected_rx_time = current_slot_start + tsch_timing[tsch_ts_tx_offset];
/* Default start time: expected Rx time */
rx_start_time = expected_rx_time;
current_input = &input_array[input_index];
/* Wait before starting to listen */
TSCH_SCHEDULE_AND_YIELD(pt, t, current_slot_start, tsch_timing[tsch_ts_rx_offset] - RADIO_DELAY_BEFORE_RX, "RxBeforeListen");
TSCH_DEBUG_RX_EVENT();
/* Start radio for at least guard time */
NETSTACK_RADIO.on();
if(!NETSTACK_RADIO.receiving_packet()) {
/* Check if receiving within guard time */
BUSYWAIT_UNTIL_ABS(NETSTACK_RADIO.receiving_packet(),
current_slot_start, tsch_timing[tsch_ts_rx_offset] + tsch_timing[tsch_ts_rx_wait]);
TSCH_DEBUG_RX_EVENT();
/* Save packet timestamp */
rx_start_time = RTIMER_NOW();
}
if(!NETSTACK_RADIO.receiving_packet() && !NETSTACK_RADIO.pending_packet()) {
NETSTACK_RADIO.off();
/* no packets on air */
} else {
/* Wait until packet is received, turn radio off */
BUSYWAIT_UNTIL_ABS(!NETSTACK_RADIO.receiving_packet(),
current_slot_start, tsch_timing[tsch_ts_rx_offset] + tsch_timing[tsch_ts_rx_wait] + tsch_timing[tsch_ts_max_tx]);
TSCH_DEBUG_RX_EVENT();
NETSTACK_RADIO.off();
#if TSCH_RESYNC_WITH_SFD_TIMESTAMPS
/* At the end of the reception, get an more accurate estimate of SFD arrival time */
NETSTACK_RADIO.get_object(RADIO_PARAM_LAST_PACKET_TIMESTAMP, &rx_start_time, sizeof(rtimer_clock_t));
#endif
if(NETSTACK_RADIO.pending_packet()) {
static int frame_valid;
static int header_len;
static frame802154_t frame;
radio_value_t radio_last_rssi;
NETSTACK_RADIO.get_value(RADIO_PARAM_LAST_RSSI, &radio_last_rssi);
/* Read packet */
current_input->len = NETSTACK_RADIO.read((void *)current_input->payload, TSCH_PACKET_MAX_LEN);
current_input->rx_asn = current_asn;
current_input->rssi = (signed)radio_last_rssi;
header_len = frame802154_parse((uint8_t *)current_input->payload, current_input->len, &frame);
frame_valid = header_len > 0 &&
frame802154_check_dest_panid(&frame) &&
frame802154_extract_linkaddr(&frame, &source_address, &destination_address);
packet_duration = TSCH_PACKET_DURATION(current_input->len);
#if TSCH_SECURITY_ENABLED
/* Decrypt and verify incoming frame */
if(frame_valid) {
if(tsch_security_parse_frame(
current_input->payload, header_len, current_input->len - header_len - tsch_security_mic_len(&frame),
&frame, &source_address, &current_asn)) {
current_input->len -= tsch_security_mic_len(&frame);
} else {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!failed to authenticate frame %u", current_input->len));
frame_valid = 0;
}
} else {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!failed to parse frame %u %u", header_len, current_input->len));
frame_valid = 0;
}
#endif /* TSCH_SECURITY_ENABLED */
if(frame_valid) {
if(linkaddr_cmp(&destination_address, &linkaddr_node_addr)
|| linkaddr_cmp(&destination_address, &linkaddr_null)) {
int do_nack = 0;
estimated_drift = ((int32_t)expected_rx_time - (int32_t)rx_start_time);
#ifdef TSCH_CALLBACK_DO_NACK
if(frame.fcf.ack_required) {
do_nack = TSCH_CALLBACK_DO_NACK(current_link,
&source_address, &destination_address);
}
#endif
if(frame.fcf.ack_required) {
static uint8_t ack_buf[TSCH_PACKET_MAX_LEN];
static int ack_len;
/* Build ACK frame */
ack_len = tsch_packet_create_eack(ack_buf, sizeof(ack_buf),
&source_address, frame.seq, (int16_t)RTIMERTICKS_TO_US(estimated_drift), do_nack);
#if TSCH_SECURITY_ENABLED
if(tsch_is_pan_secured) {
/* Secure ACK frame. There is only header and header IEs, therefore data len == 0. */
ack_len += tsch_security_secure_frame(ack_buf, ack_buf, ack_len, 0, &current_asn);
}
#endif /* TSCH_SECURITY_ENABLED */
/* Copy to radio buffer */
NETSTACK_RADIO.prepare((const void *)ack_buf, ack_len);
/* Wait for time to ACK and transmit ACK */
TSCH_SCHEDULE_AND_YIELD(pt, t, rx_start_time,
packet_duration + tsch_timing[tsch_ts_tx_ack_delay] - RADIO_DELAY_BEFORE_TX, "RxBeforeAck");
TSCH_DEBUG_RX_EVENT();
NETSTACK_RADIO.transmit(ack_len);
}
/* If the sender is a time source, proceed to clock drift compensation */
n = tsch_queue_get_nbr(&source_address);
if(n != NULL && n->is_time_source) {
/* Keep track of last sync time */
last_sync_asn = current_asn;
/* Save estimated drift */
drift_correction = -estimated_drift;
drift_neighbor = n;
tsch_schedule_keepalive();
}
/* Add current input to ringbuf */
ringbufindex_put(&input_ringbuf);
/* Log every reception */
TSCH_LOG_ADD(tsch_log_rx,
log->rx.src = TSCH_LOG_ID_FROM_LINKADDR((linkaddr_t*)&frame.src_addr);
log->rx.is_unicast = frame.fcf.ack_required;
log->rx.datalen = current_input->len;
log->rx.drift = drift_correction;
log->rx.drift_used = drift_neighbor != NULL;
log->rx.is_data = frame.fcf.frame_type == FRAME802154_DATAFRAME;
log->rx.sec_level = frame.aux_hdr.security_control.security_level;
log->rx.estimated_drift = estimated_drift;
);
} else {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!not for us %x:%x:%x:%x",
destination_address.u8[4], destination_address.u8[5],
destination_address.u8[6], destination_address.u8[7]);
);
}
/* Poll process for processing of pending input and logs */
process_poll(&tsch_pending_events_process);
}
}
}
if(input_queue_drop != 0) {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!queue full skipped %u", input_queue_drop);
);
input_queue_drop = 0;
}
}
TSCH_DEBUG_RX_EVENT();
PT_END(pt);
}
/*---------------------------------------------------------------------------*/
/* Protothread for slot operation, called from rtimer interrupt
* and scheduled from tsch_schedule_slot_operation */
static
PT_THREAD(tsch_slot_operation(struct rtimer *t, void *ptr))
{
TSCH_DEBUG_INTERRUPT();
PT_BEGIN(&slot_operation_pt);
/* Loop over all active slots */
while(tsch_is_associated) {
if(current_link == NULL || tsch_lock_requested) { /* Skip slot operation if there is no link
or if there is a pending request for getting the lock */
/* Issue a log whenever skipping a slot */
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"!skipped slot %u %u %u",
tsch_locked,
tsch_lock_requested,
current_link == NULL);
);
} else {
uint8_t current_channel;
TSCH_DEBUG_SLOT_START();
tsch_in_slot_operation = 1;
/* Get a packet ready to be sent */
current_packet = get_packet_and_neighbor_for_link(current_link, &current_neighbor);
/* There is no packet to send, and this link does not have Rx flag. Instead of doing
* nothing, switch to the backup link (has Rx flag) if any. */
if(current_packet == NULL && !(current_link->link_options & LINK_OPTION_RX) && backup_link != NULL) {
current_link = backup_link;
current_packet = get_packet_and_neighbor_for_link(current_link, &current_neighbor);
}
/* Hop channel */
current_channel = tsch_calculate_channel(&current_asn, current_link->channel_offset);
NETSTACK_RADIO.set_value(RADIO_PARAM_CHANNEL, current_channel);
/* Reset drift correction */
drift_correction = 0;
drift_neighbor = NULL;
/* Decide whether it is a TX/RX/IDLE or OFF slot */
/* Actual slot operation */
if(current_packet != NULL) {
/* We have something to transmit, do the following:
* 1. send
* 2. update_backoff_state(current_neighbor)
* 3. post tx callback
**/
static struct pt slot_tx_pt;
PT_SPAWN(&slot_operation_pt, &slot_tx_pt, tsch_tx_slot(&slot_tx_pt, t));
} else if((current_link->link_options & LINK_OPTION_RX)) {
/* Listen */
static struct pt slot_rx_pt;
PT_SPAWN(&slot_operation_pt, &slot_rx_pt, tsch_rx_slot(&slot_rx_pt, t));
}
TSCH_DEBUG_SLOT_END();
}
/* End of slot operation, schedule next slot or resynchronize */
/* Do we need to resynchronize? i.e., wait for EB again */
if(!tsch_is_coordinator && (ASN_DIFF(current_asn, last_sync_asn) >
(100 * TSCH_CLOCK_TO_SLOTS(TSCH_DESYNC_THRESHOLD / 100, tsch_timing[tsch_ts_timeslot_length])))) {
TSCH_LOG_ADD(tsch_log_message,
snprintf(log->message, sizeof(log->message),
"! leaving the network, last sync %u",
(unsigned)ASN_DIFF(current_asn, last_sync_asn));
);
tsch_disassociate();
} else {
/* backup of drift correction for printing debug messages */
/* int32_t drift_correction_backup = drift_correction; */
uint16_t timeslot_diff = 0;
rtimer_clock_t prev_slot_start;
/* Time to next wake up */
rtimer_clock_t time_to_next_active_slot;
/* Schedule next wakeup skipping slots if missed deadline */
do {
if(current_link != NULL
&& current_link->link_options & LINK_OPTION_TX
&& current_link->link_options & LINK_OPTION_SHARED) {
/* Decrement the backoff window for all neighbors able to transmit over
* this Tx, Shared link. */
tsch_queue_update_all_backoff_windows(&current_link->addr);
}
/* Get next active link */
current_link = tsch_schedule_get_next_active_link(&current_asn, &timeslot_diff, &backup_link);
if(current_link == NULL) {
/* There is no next link. Fall back to default
* behavior: wake up at the next slot. */
timeslot_diff = 1;
}
/* Update ASN */
ASN_INC(current_asn, timeslot_diff);
/* Time to next wake up */
time_to_next_active_slot = timeslot_diff * tsch_timing[tsch_ts_timeslot_length] + drift_correction;
drift_correction = 0;
drift_neighbor = NULL;
/* Update current slot start */
prev_slot_start = current_slot_start;
current_slot_start += time_to_next_active_slot;
} while(!tsch_schedule_slot_operation(t, prev_slot_start, time_to_next_active_slot, 1, "main"));
}
tsch_in_slot_operation = 0;
PT_YIELD(&slot_operation_pt);
}
PT_END(&slot_operation_pt);
}
/*---------------------------------------------------------------------------*/
/* Set global time before starting slot operation,
* with a rtimer time and an ASN */
void
tsch_slot_operation_start(void)
{
static struct rtimer slot_operation_timer;
rtimer_clock_t time_to_next_active_slot;
rtimer_clock_t prev_slot_start;
TSCH_DEBUG_INIT();
do {
uint16_t timeslot_diff;
/* Get next active link */
current_link = tsch_schedule_get_next_active_link(&current_asn, &timeslot_diff, &backup_link);
if(current_link == NULL) {
/* There is no next link. Fall back to default
* behavior: wake up at the next slot. */
timeslot_diff = 1;
}
/* Update ASN */
ASN_INC(current_asn, timeslot_diff);
/* Time to next wake up */
time_to_next_active_slot = timeslot_diff * tsch_timing[tsch_ts_timeslot_length];
/* Update current slot start */
prev_slot_start = current_slot_start;
current_slot_start += time_to_next_active_slot;
} while(!tsch_schedule_slot_operation(&slot_operation_timer, prev_slot_start, time_to_next_active_slot, 1, "association"));
}
/*---------------------------------------------------------------------------*/
/* Start actual slot operation */
void
tsch_slot_operation_sync(rtimer_clock_t next_slot_start,
struct asn_t *next_slot_asn)
{
current_slot_start = next_slot_start;
current_asn = *next_slot_asn;
last_sync_asn = current_asn;
current_link = NULL;
}
/*---------------------------------------------------------------------------*/
Reference in a new issue Copy permalink