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|
/*
/ _____) _ | |
( (____ _____ ____ _| |_ _____ ____| |__
\____ \| ___ | (_ _) ___ |/ ___) _ \
_____) ) ____| | | || |_| ____( (___| | | |
(______/|_____)_|_|_| \__)_____)\____)_| |_|
(C)2013 Semtech-Cycleo
Description:
Functions used to handle the Listen Before Talk feature
License: Revised BSD License, see LICENSE.TXT file include in the project
Maintainer: Michael Coracin
*/
/* -------------------------------------------------------------------------- */
/* --- DEPENDANCIES --------------------------------------------------------- */
#include <stdint.h> /* C99 types */
#include <stdbool.h> /* bool type */
#include <stdio.h> /* printf fprintf */
#include <stdlib.h> /* abs, labs, llabs */
#include <string.h> /* memset */
#include "loragw_radio.h"
#include "loragw_aux.h"
#include "loragw_lbt.h"
#include "loragw_fpga.h"
/* -------------------------------------------------------------------------- */
/* --- PRIVATE MACROS ------------------------------------------------------- */
#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
#if DEBUG_LBT == 1
#define DEBUG_MSG(str) fprintf(stderr, str)
#define DEBUG_PRINTF(fmt, args...) fprintf(stderr,"%s:%d: "fmt, __FUNCTION__, __LINE__, args)
#define CHECK_NULL(a) if(a==NULL){fprintf(stderr,"%s:%d: ERROR: NULL POINTER AS ARGUMENT\n", __FUNCTION__, __LINE__);return LGW_REG_ERROR;}
#else
#define DEBUG_MSG(str)
#define DEBUG_PRINTF(fmt, args...)
#define CHECK_NULL(a) if(a==NULL){return LGW_REG_ERROR;}
#endif
#define LBT_TIMESTAMP_MASK 0x007FF000 /* 11-bits timestamp */
/* -------------------------------------------------------------------------- */
/* --- PRIVATE TYPES -------------------------------------------------------- */
/* -------------------------------------------------------------------------- */
/* --- PRIVATE CONSTANTS ---------------------------------------------------- */
/* -------------------------------------------------------------------------- */
/* --- INTERNAL SHARED VARIABLES -------------------------------------------- */
extern void *lgw_spi_target; /*! generic pointer to the SPI device */
extern uint8_t lgw_spi_mux_mode; /*! current SPI mux mode used */
extern uint16_t lgw_i_tx_start_delay_us;
/* -------------------------------------------------------------------------- */
/* --- PRIVATE VARIABLES ---------------------------------------------------- */
static bool lbt_enable;
static uint8_t lbt_nb_active_channel;
static int8_t lbt_rssi_target_dBm;
static int8_t lbt_rssi_offset_dB;
static uint32_t lbt_start_freq;
static struct lgw_conf_lbt_chan_s lbt_channel_cfg[LBT_CHANNEL_FREQ_NB];
/* -------------------------------------------------------------------------- */
/* --- PRIVATE FUNCTIONS ---------------------------------------------------- */
bool is_equal_freq(uint32_t a, uint32_t b);
/* -------------------------------------------------------------------------- */
/* --- PUBLIC FUNCTIONS DEFINITION ------------------------------------------ */
int lbt_setconf(struct lgw_conf_lbt_s * conf) {
int i;
/* Check input parameters */
if (conf == NULL) {
return LGW_LBT_ERROR;
}
if ((conf->nb_channel < 1) || (conf->nb_channel > LBT_CHANNEL_FREQ_NB)) {
DEBUG_PRINTF("ERROR: Number of defined LBT channels is out of range (%u)\n", conf->nb_channel);
return LGW_LBT_ERROR;
}
/* Initialize LBT channels configuration */
memset(lbt_channel_cfg, 0, sizeof lbt_channel_cfg);
/* Set internal LBT config according to parameters */
lbt_enable = conf->enable;
lbt_nb_active_channel = conf->nb_channel;
lbt_rssi_target_dBm = conf->rssi_target;
lbt_rssi_offset_dB = conf->rssi_offset;
for (i=0; i<lbt_nb_active_channel; i++) {
lbt_channel_cfg[i].freq_hz = conf->channels[i].freq_hz;
lbt_channel_cfg[i].scan_time_us = conf->channels[i].scan_time_us;
}
return LGW_LBT_SUCCESS;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
int lbt_setup(void) {
int x, i;
int32_t val;
uint32_t freq_offset;
/* Check if LBT feature is supported by FPGA */
x = lgw_fpga_reg_r(LGW_FPGA_FEATURE, &val);
if (x != LGW_REG_SUCCESS) {
DEBUG_MSG("ERROR: Failed to read FPGA Features register\n");
return LGW_LBT_ERROR;
}
if (TAKE_N_BITS_FROM((uint8_t)val, 2, 1) != 1) {
DEBUG_MSG("ERROR: No support for LBT in FPGA\n");
return LGW_LBT_ERROR;
}
/* Get FPGA lowest frequency for LBT channels */
x = lgw_fpga_reg_r(LGW_FPGA_LBT_INITIAL_FREQ, &val);
if (x != LGW_REG_SUCCESS) {
DEBUG_MSG("ERROR: Failed to read LBT initial frequency from FPGA\n");
return LGW_LBT_ERROR;
}
switch(val) {
case 0:
lbt_start_freq = 915000000;
break;
case 1:
lbt_start_freq = 863000000;
break;
default:
DEBUG_PRINTF("ERROR: LBT start frequency %d is not supported\n", val);
return LGW_LBT_ERROR;
}
/* Configure SX127x for FSK */
x = lgw_setup_sx127x(lbt_start_freq, MOD_FSK, LGW_SX127X_RXBW_100K_HZ, lbt_rssi_offset_dB); /* 200KHz LBT channels */
if (x != LGW_REG_SUCCESS) {
DEBUG_MSG("ERROR: Failed to configure SX127x for LBT\n");
return LGW_LBT_ERROR;
}
/* Configure FPGA for LBT */
val = -2*lbt_rssi_target_dBm; /* Convert RSSI target in dBm to FPGA register format */
x = lgw_fpga_reg_w(LGW_FPGA_RSSI_TARGET, val);
if (x != LGW_REG_SUCCESS) {
DEBUG_MSG("ERROR: Failed to configure FPGA for LBT\n");
return LGW_LBT_ERROR;
}
/* Set default values for non-active LBT channels */
for (i=lbt_nb_active_channel; i<LBT_CHANNEL_FREQ_NB; i++) {
lbt_channel_cfg[i].freq_hz = lbt_start_freq;
lbt_channel_cfg[i].scan_time_us = 128; /* fastest scan for non-active channels */
}
/* Configure FPGA for both active and non-active LBT channels */
for (i=0; i<LBT_CHANNEL_FREQ_NB; i++) {
/* Check input parameters */
if (lbt_channel_cfg[i].freq_hz < lbt_start_freq) {
DEBUG_PRINTF("ERROR: LBT channel frequency is out of range (%u)\n", lbt_channel_cfg[i].freq_hz);
return LGW_LBT_ERROR;
}
if ((lbt_channel_cfg[i].scan_time_us != 128) && (lbt_channel_cfg[i].scan_time_us != 5000)) {
DEBUG_PRINTF("ERROR: LBT channel scan time is not supported (%u)\n", lbt_channel_cfg[i].scan_time_us);
return LGW_LBT_ERROR;
}
/* Configure */
freq_offset = (lbt_channel_cfg[i].freq_hz - lbt_start_freq) / 100E3; /* 100kHz unit */
x = lgw_fpga_reg_w(LGW_FPGA_LBT_CH0_FREQ_OFFSET+i, (int32_t)freq_offset);
if (x != LGW_REG_SUCCESS) {
DEBUG_PRINTF("ERROR: Failed to configure FPGA for LBT channel %d (freq offset)\n", i);
return LGW_LBT_ERROR;
}
if (lbt_channel_cfg[i].scan_time_us == 5000) { /* configured to 128 by default */
x = lgw_fpga_reg_w(LGW_FPGA_LBT_SCAN_TIME_CH0+i, 1);
if (x != LGW_REG_SUCCESS) {
DEBUG_PRINTF("ERROR: Failed to configure FPGA for LBT channel %d (freq offset)\n", i);
return LGW_LBT_ERROR;
}
}
}
DEBUG_MSG("Note: LBT configuration:\n");
DEBUG_PRINTF("\tlbt_enable: %d\n", lbt_enable );
DEBUG_PRINTF("\tlbt_nb_active_channel: %d\n", lbt_nb_active_channel );
DEBUG_PRINTF("\tlbt_start_freq: %d\n", lbt_start_freq);
DEBUG_PRINTF("\tlbt_rssi_target: %d\n", lbt_rssi_target_dBm );
for (i=0; i<LBT_CHANNEL_FREQ_NB; i++) {
DEBUG_PRINTF("\tlbt_channel_cfg[%d].freq_hz: %u\n", i, lbt_channel_cfg[i].freq_hz );
DEBUG_PRINTF("\tlbt_channel_cfg[%d].scan_time_us: %u\n", i, lbt_channel_cfg[i].scan_time_us );
}
return LGW_LBT_SUCCESS;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
int lbt_start(void) {
int x;
x = lgw_fpga_reg_w(LGW_FPGA_CTRL_FEATURE_START, 1);
if (x != LGW_REG_SUCCESS) {
DEBUG_MSG("ERROR: Failed to start LBT FSM\n");
return LGW_LBT_ERROR;
}
return LGW_LBT_SUCCESS;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
int lbt_is_channel_free(struct lgw_pkt_tx_s * pkt_data, uint16_t tx_start_delay, bool * tx_allowed) {
int i;
int32_t val;
uint32_t tx_start_time = 0;
uint32_t tx_end_time = 0;
uint32_t delta_time = 0;
uint32_t sx1301_time = 0;
uint32_t lbt_time = 0;
uint32_t lbt_time1 = 0;
uint32_t lbt_time2 = 0;
uint32_t tx_max_time = 0;
int lbt_channel_decod_1 = -1;
int lbt_channel_decod_2 = -1;
uint32_t packet_duration = 0;
/* Check input parameters */
if ((pkt_data == NULL) || (tx_allowed == NULL)) {
return LGW_LBT_ERROR;
}
/* Check if TX is allowed */
if (lbt_enable == true) {
/* TX allowed for LoRa only */
if (pkt_data->modulation != MOD_LORA) {
*tx_allowed = false;
DEBUG_PRINTF("INFO: TX is not allowed for this modulation (%x)\n", pkt_data->modulation);
return LGW_LBT_SUCCESS;
}
/* Get SX1301 time at last PPS */
lgw_get_trigcnt(&sx1301_time);
DEBUG_MSG("################################\n");
switch(pkt_data->tx_mode) {
case TIMESTAMPED:
DEBUG_MSG("tx_mode = TIMESTAMPED\n");
tx_start_time = pkt_data->count_us & LBT_TIMESTAMP_MASK;
break;
case ON_GPS:
DEBUG_MSG("tx_mode = ON_GPS\n");
tx_start_time = (sx1301_time + (uint32_t)tx_start_delay + 1000000) & LBT_TIMESTAMP_MASK;
break;
case IMMEDIATE:
DEBUG_MSG("ERROR: tx_mode IMMEDIATE is not supported when LBT is enabled\n");
/* FALLTHROUGH */
default:
return LGW_LBT_ERROR;
}
/* Select LBT Channel corresponding to required TX frequency */
lbt_channel_decod_1 = -1;
lbt_channel_decod_2 = -1;
if (pkt_data->bandwidth == BW_125KHZ) {
for (i=0; i<lbt_nb_active_channel; i++) {
if (is_equal_freq(pkt_data->freq_hz, lbt_channel_cfg[i].freq_hz) == true) {
DEBUG_PRINTF("LBT: select channel %d (%u Hz)\n", i, lbt_channel_cfg[i].freq_hz);
lbt_channel_decod_1 = i;
lbt_channel_decod_2 = i;
if (lbt_channel_cfg[i].scan_time_us == 5000) {
tx_max_time = 4000000; /* 4 seconds */
} else { /* scan_time_us = 128 */
tx_max_time = 400000; /* 400 milliseconds */
}
break;
}
}
} else if (pkt_data->bandwidth == BW_250KHZ) {
/* In case of 250KHz, the TX freq has to be in between 2 consecutive channels of 200KHz BW.
The TX can only be over 2 channels, not more */
for (i=0; i<(lbt_nb_active_channel-1); i++) {
if ((is_equal_freq(pkt_data->freq_hz, (lbt_channel_cfg[i].freq_hz+lbt_channel_cfg[i+1].freq_hz)/2) == true) && ((lbt_channel_cfg[i+1].freq_hz-lbt_channel_cfg[i].freq_hz)==200E3)) {
DEBUG_PRINTF("LBT: select channels %d,%d (%u Hz)\n", i, i+1, (lbt_channel_cfg[i].freq_hz+lbt_channel_cfg[i+1].freq_hz)/2);
lbt_channel_decod_1 = i;
lbt_channel_decod_2 = i+1;
if (lbt_channel_cfg[i].scan_time_us == 5000) {
tx_max_time = 4000000; /* 4 seconds */
} else { /* scan_time_us = 128 */
tx_max_time = 200000; /* 200 milliseconds */
}
break;
}
}
} else {
/* Nothing to do for now */
}
/* Get last time when selected channel was free */
if ((lbt_channel_decod_1 >= 0) && (lbt_channel_decod_2 >= 0)) {
lgw_fpga_reg_w(LGW_FPGA_LBT_TIMESTAMP_SELECT_CH, (int32_t)lbt_channel_decod_1);
lgw_fpga_reg_r(LGW_FPGA_LBT_TIMESTAMP_CH, &val);
lbt_time = lbt_time1 = (uint32_t)(val & 0x0000FFFF) * 256; /* 16bits (1LSB = 256µs) */
if (lbt_channel_decod_1 != lbt_channel_decod_2 ) {
lgw_fpga_reg_w(LGW_FPGA_LBT_TIMESTAMP_SELECT_CH, (int32_t)lbt_channel_decod_2);
lgw_fpga_reg_r(LGW_FPGA_LBT_TIMESTAMP_CH, &val);
lbt_time2 = (uint32_t)(val & 0x0000FFFF) * 256; /* 16bits (1LSB = 256µs) */
if (lbt_time2 < lbt_time1) {
lbt_time = lbt_time2;
}
}
} else {
lbt_time = 0;
}
packet_duration = lgw_time_on_air(pkt_data) * 1000UL;
tx_end_time = (tx_start_time + packet_duration) & LBT_TIMESTAMP_MASK;
if (lbt_time < tx_end_time) {
delta_time = tx_end_time - lbt_time;
} else {
/* It means LBT counter has wrapped */
printf("LBT: lbt counter has wrapped\n");
delta_time = (LBT_TIMESTAMP_MASK - lbt_time) + tx_end_time;
}
DEBUG_PRINTF("sx1301_time = %u\n", sx1301_time & LBT_TIMESTAMP_MASK);
DEBUG_PRINTF("tx_freq = %u\n", pkt_data->freq_hz);
DEBUG_MSG("------------------------------------------------\n");
DEBUG_PRINTF("packet_duration = %u\n", packet_duration);
DEBUG_PRINTF("tx_start_time = %u\n", tx_start_time);
DEBUG_PRINTF("lbt_time1 = %u\n", lbt_time1);
DEBUG_PRINTF("lbt_time2 = %u\n", lbt_time2);
DEBUG_PRINTF("lbt_time = %u\n", lbt_time);
DEBUG_PRINTF("delta_time = %u\n", delta_time);
DEBUG_MSG("------------------------------------------------\n");
/* send data if allowed */
/* lbt_time: last time when channel was free */
/* tx_max_time: maximum time allowed to send packet since last free time */
/* 2048: some margin */
// if ((delta_time <= (tx_max_time - 2048)) && (lbt_time != 0)) {
// delta time check did not allow 400 ms packets, change to simple check against packet duration
// Japan STD regulations allow 400ms packet duration from start of tx
if ((packet_duration <= (tx_max_time)) && (lbt_time != 0)) {
*tx_allowed = true;
} else {
DEBUG_MSG("ERROR: TX request rejected (LBT)\n");
*tx_allowed = false;
}
} else {
/* Always allow if LBT is disabled */
*tx_allowed = true;
}
return LGW_LBT_SUCCESS;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
bool lbt_is_enabled(void) {
return lbt_enable;
}
/* -------------------------------------------------------------------------- */
/* --- PRIVATE FUNCTIONS DEFINITION ----------------------------------------- */
/* As given frequencies have been converted from float to integer, some aliasing
issues can appear, so we can't simply check for equality, but have to take some
margin */
bool is_equal_freq(uint32_t a, uint32_t b) {
int64_t diff;
int64_t a64 = (int64_t)a;
int64_t b64 = (int64_t)b;
/* Calculate the difference */
diff = llabs(a64 - b64);
/* Check for acceptable diff range */
if( diff <= 10000 )
{
return true;
}
return false;
}
/* --- EOF ------------------------------------------------------------------ */
|
