src/ap/bss_load.c

/*
 * BSS Load Element / Channel Utilization
 * Copyright (c) 2014, Qualcomm Atheros, Inc.
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#include "utils/includes.h"

#include "utils/common.h"
#include "utils/eloop.h"
#include "hostapd.h"
#include "bss_load.h"
#include "ap_drv_ops.h"
#include "beacon.h"


static int get_bss_load_update_timeout(struct hostapd_data *hapd,
				       unsigned int *sec, unsigned int *usec)
{
	unsigned int update_period = hapd->conf->bss_load_update_period;
	unsigned int beacon_int = hapd->iconf->beacon_int;
	unsigned int update_timeout;

	if (!update_period || !beacon_int) {
		wpa_printf(MSG_ERROR,
			   "BSS Load: Invalid BSS load update configuration (period=%u beacon_int=%u)",
			   update_period, beacon_int);
		return -1;
	}

	update_timeout = update_period * beacon_int;

	*sec = ((update_timeout / 1000) * 1024) / 1000;
	*usec = (update_timeout % 1000) * 1024;

	return 0;
}


static void update_channel_utilization(void *eloop_data, void *user_data)
{
	struct hostapd_data *hapd = eloop_data;
	unsigned int sec, usec;
	int err;
	struct hostapd_iface *iface = hapd->iface;

	if (!(hapd->beacon_set_done && hapd->started))
		return;

	err = hostapd_drv_get_survey(hapd, hapd->iface->freq);
	if (err) {
		wpa_printf(MSG_ERROR, "BSS Load: Failed to get survey data");
		return;
	}

	ieee802_11_set_beacon(hapd);

	if (get_bss_load_update_timeout(hapd, &sec, &usec) < 0)
		return;

	if (hapd->conf->chan_util_avg_period) {
		iface->chan_util_samples_sum += iface->channel_utilization;
		iface->chan_util_num_sample_periods +=
			hapd->conf->bss_load_update_period;
		if (iface->chan_util_num_sample_periods >=
		    hapd->conf->chan_util_avg_period) {
			iface->chan_util_average =
				iface->chan_util_samples_sum /
				(iface->chan_util_num_sample_periods /
				 hapd->conf->bss_load_update_period);
			iface->chan_util_samples_sum = 0;
			iface->chan_util_num_sample_periods = 0;
		}
	}

	eloop_register_timeout(sec, usec, update_channel_utilization, hapd,
			       NULL);
}


int bss_load_update_init(struct hostapd_data *hapd)
{
	unsigned int sec, usec;

	if (get_bss_load_update_timeout(hapd, &sec, &usec) < 0)
		return -1;

	eloop_register_timeout(sec, usec, update_channel_utilization, hapd,
			       NULL);
	return 0;
}


void bss_load_update_deinit(struct hostapd_data *hapd)
{
	eloop_cancel_timeout(update_channel_utilization, hapd, NULL);
}