/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2003, 2004 David Young.  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. The name of David Young may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY David Young ``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 David
 * Young 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.
 */

#include <sys/types.h>
#include <sys/byteorder.h>
#include <sys/conf.h>
#include <sys/cmn_err.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/stream.h>
#include <sys/strsun.h>
#include <sys/modctl.h>
#include <sys/devops.h>
#include <sys/dlpi.h>
#include <sys/gld.h>
#include <sys/varargs.h>
#include <sys/pci.h>
#include <sys/net80211.h>

#include "ral_rate.h"

#define MAX(a, b) ((a) > (b) ? (a) : (b))

#ifdef interpolate
#undef interpolate
#endif
#define interpolate(parm, old, new)     \
        ((parm##_old * (old) + \
        (parm##_denom - parm##_old) * (new)) /  \
        parm##_denom)

static struct ral_rssadapt_expavgctl master_expavgctl;

void
ral_rate_init(void)
{
        master_expavgctl.rc_decay_denom = 16;
        master_expavgctl.rc_decay_old = 15;
        master_expavgctl.rc_thresh_denom = 8;
        master_expavgctl.rc_thresh_old = 4;
        master_expavgctl.rc_avgrssi_denom = 8;
        master_expavgctl.rc_avgrssi_old = 4;
}

/* ARGSUSED */
int
ral_rssadapt_choose(struct ral_rssadapt *ra, struct ieee80211_rateset *rs,
    struct ieee80211_frame *wh, uint32_t len,
    const char *dvname, int do_not_adapt)
{
        uint16_t (*thrs)[IEEE80211_RATE_SIZE];
        int flags = 0, i, rateidx = 0, thridx, top;

        if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) == IEEE80211_FC0_TYPE_CTL)
                flags |= IEEE80211_RATE_BASIC;

        for (i = 0, top = RAL_RSSADAPT_BKT0;
            i < RAL_RSSADAPT_BKTS;
            i++, top <<= RAL_RSSADAPT_BKTPOWER) {
                thridx = i;
                if (len <= top)
                        break;
        }

        thrs = &ra->ra_rate_thresh[thridx];

        i = rs->ir_nrates;
        while (--i >= 0) {
                rateidx = i;
                if ((rs->ir_rates[i] & flags) != flags)
                        continue;
                if (do_not_adapt)
                        break;
                if ((*thrs)[i] < ra->ra_avg_rssi)
                        break;
        }

        return (rateidx);
}

void
ral_rssadapt_updatestats(struct ral_rssadapt *ra)
{
        long interval;

        ra->ra_pktrate =
            (ra->ra_pktrate + 10 * (ra->ra_nfail + ra->ra_nok)) / 2;
        ra->ra_nfail = ra->ra_nok = 0;

        /*
         * a node is eligible for its rate to be raised every 1/10 to 10
         * seconds, more eligible in proportion to recent packet rates.
         */
        interval = MAX(100000, 10000000 / MAX(1, 10 * ra->ra_pktrate));
        ra->ra_raise_interval.tv_sec = interval / (1000 * 1000);
        ra->ra_raise_interval.tv_usec = interval % (1000 * 1000);
}

/* ARGSUSED */
void
ral_rssadapt_input(struct ieee80211com *ic, struct ieee80211_node *ni,
    struct ral_rssadapt *ra, int rssi)
{
        ra->ra_avg_rssi = interpolate(master_expavgctl.rc_avgrssi,
            ra->ra_avg_rssi, (rssi << 8));
}

/*
 * Adapt the data rate to suit the conditions.  When a transmitted
 * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
 * raise the RSS threshold for transmitting packets of similar length at
 * the same data rate.
 */
/* ARGSUSED */
void
ral_rssadapt_lower_rate(struct ieee80211com *ic, struct ieee80211_node *ni,
    struct ral_rssadapt *ra, struct ral_rssdesc *id)
{
        struct ieee80211_rateset *rs = &ni->in_rates;
        uint16_t last_thr;
        uint32_t i, thridx, top;

        ra->ra_nfail++;

        if (id->id_rateidx >= rs->ir_nrates)
                return;

        for (i = 0, top = RAL_RSSADAPT_BKT0;
            i < RAL_RSSADAPT_BKTS;
            i++, top <<= RAL_RSSADAPT_BKTPOWER) {
                thridx = i;
                if (id->id_len <= top)
                        break;
        }

        last_thr = ra->ra_rate_thresh[thridx][id->id_rateidx];
        ra->ra_rate_thresh[thridx][id->id_rateidx] =
            interpolate(master_expavgctl.rc_thresh, last_thr,
            (id->id_rssi << 8));
}

/* ARGSUSED */
void
ral_rssadapt_raise_rate(struct ieee80211com *ic, struct ral_rssadapt *ra,
    struct ral_rssdesc *id)
{
        uint16_t (*thrs)[IEEE80211_RATE_SIZE], newthr, oldthr;
        struct ieee80211_node *ni = id->id_node;
        struct ieee80211_rateset *rs = &ni->in_rates;
        int i, top;

        ra->ra_nok++;

        for (i = 0, top = RAL_RSSADAPT_BKT0;
            i < RAL_RSSADAPT_BKTS;
            i++, top <<= RAL_RSSADAPT_BKTPOWER) {
                thrs = &ra->ra_rate_thresh[i];
                if (id->id_len <= top)
                        break;
        }

        if (id->id_rateidx + 1 < rs->ir_nrates &&
            (*thrs)[id->id_rateidx + 1] > (*thrs)[id->id_rateidx]) {
                oldthr = (*thrs)[id->id_rateidx + 1];
                if ((*thrs)[id->id_rateidx] == 0)
                        newthr = ra->ra_avg_rssi;
                else
                        newthr = (*thrs)[id->id_rateidx];
                (*thrs)[id->id_rateidx + 1] =
                    interpolate(master_expavgctl.rc_decay, oldthr, newthr);
        }
}