linux/net/mac80211/rc80211_minstrel.c
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   1/*
   2 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * Based on minstrel.c:
   9 *   Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
  10 *   Sponsored by Indranet Technologies Ltd
  11 *
  12 * Based on sample.c:
  13 *   Copyright (c) 2005 John Bicket
  14 *   All rights reserved.
  15 *
  16 *   Redistribution and use in source and binary forms, with or without
  17 *   modification, are permitted provided that the following conditions
  18 *   are met:
  19 *   1. Redistributions of source code must retain the above copyright
  20 *      notice, this list of conditions and the following disclaimer,
  21 *      without modification.
  22 *   2. Redistributions in binary form must reproduce at minimum a disclaimer
  23 *      similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
  24 *      redistribution must be conditioned upon including a substantially
  25 *      similar Disclaimer requirement for further binary redistribution.
  26 *   3. Neither the names of the above-listed copyright holders nor the names
  27 *      of any contributors may be used to endorse or promote products derived
  28 *      from this software without specific prior written permission.
  29 *
  30 *   Alternatively, this software may be distributed under the terms of the
  31 *   GNU General Public License ("GPL") version 2 as published by the Free
  32 *   Software Foundation.
  33 *
  34 *   NO WARRANTY
  35 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  36 *   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  37 *   LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
  38 *   AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  39 *   THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
  40 *   OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  41 *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  42 *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  43 *   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  44 *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  45 *   THE POSSIBILITY OF SUCH DAMAGES.
  46 */
  47#include <linux/netdevice.h>
  48#include <linux/types.h>
  49#include <linux/skbuff.h>
  50#include <linux/debugfs.h>
  51#include <linux/random.h>
  52#include <linux/ieee80211.h>
  53#include <linux/slab.h>
  54#include <net/mac80211.h>
  55#include "rate.h"
  56#include "rc80211_minstrel.h"
  57
  58#define SAMPLE_TBL(_mi, _idx, _col) \
  59                _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
  60
  61/* convert mac80211 rate index to local array index */
  62static inline int
  63rix_to_ndx(struct minstrel_sta_info *mi, int rix)
  64{
  65        int i = rix;
  66        for (i = rix; i >= 0; i--)
  67                if (mi->r[i].rix == rix)
  68                        break;
  69        return i;
  70}
  71
  72/* return current EMWA throughput */
  73int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
  74{
  75        int usecs;
  76
  77        usecs = mr->perfect_tx_time;
  78        if (!usecs)
  79                usecs = 1000000;
  80
  81        /* reset thr. below 10% success */
  82        if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
  83                return 0;
  84
  85        if (prob_ewma > MINSTREL_FRAC(90, 100))
  86                return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
  87        else
  88                return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
  89}
  90
  91/* find & sort topmost throughput rates */
  92static inline void
  93minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
  94{
  95        int j;
  96        struct minstrel_rate_stats *tmp_mrs;
  97        struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
  98
  99        for (j = MAX_THR_RATES; j > 0; --j) {
 100                tmp_mrs = &mi->r[tp_list[j - 1]].stats;
 101                if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
 102                    minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
 103                        break;
 104        }
 105
 106        if (j < MAX_THR_RATES - 1)
 107                memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
 108        if (j < MAX_THR_RATES)
 109                tp_list[j] = i;
 110}
 111
 112static void
 113minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
 114                  int offset, int idx)
 115{
 116        struct minstrel_rate *r = &mi->r[idx];
 117
 118        ratetbl->rate[offset].idx = r->rix;
 119        ratetbl->rate[offset].count = r->adjusted_retry_count;
 120        ratetbl->rate[offset].count_cts = r->retry_count_cts;
 121        ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
 122}
 123
 124static void
 125minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
 126{
 127        struct ieee80211_sta_rates *ratetbl;
 128        int i = 0;
 129
 130        ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
 131        if (!ratetbl)
 132                return;
 133
 134        /* Start with max_tp_rate */
 135        minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
 136
 137        if (mp->hw->max_rates >= 3) {
 138                /* At least 3 tx rates supported, use max_tp_rate2 next */
 139                minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
 140        }
 141
 142        if (mp->hw->max_rates >= 2) {
 143                /* At least 2 tx rates supported, use max_prob_rate next */
 144                minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
 145        }
 146
 147        /* Use lowest rate last */
 148        ratetbl->rate[i].idx = mi->lowest_rix;
 149        ratetbl->rate[i].count = mp->max_retry;
 150        ratetbl->rate[i].count_cts = mp->max_retry;
 151        ratetbl->rate[i].count_rts = mp->max_retry;
 152
 153        rate_control_set_rates(mp->hw, mi->sta, ratetbl);
 154}
 155
 156/*
 157* Recalculate statistics and counters of a given rate
 158*/
 159void
 160minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
 161{
 162        unsigned int cur_prob;
 163
 164        if (unlikely(mrs->attempts > 0)) {
 165                mrs->sample_skipped = 0;
 166                cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
 167                if (unlikely(!mrs->att_hist)) {
 168                        mrs->prob_ewma = cur_prob;
 169                } else {
 170                        /* update exponential weighted moving variance */
 171                        mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
 172                                                        cur_prob,
 173                                                        mrs->prob_ewma,
 174                                                        EWMA_LEVEL);
 175
 176                        /*update exponential weighted moving avarage */
 177                        mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
 178                                                       cur_prob,
 179                                                       EWMA_LEVEL);
 180                }
 181                mrs->att_hist += mrs->attempts;
 182                mrs->succ_hist += mrs->success;
 183        } else {
 184                mrs->sample_skipped++;
 185        }
 186
 187        mrs->last_success = mrs->success;
 188        mrs->last_attempts = mrs->attempts;
 189        mrs->success = 0;
 190        mrs->attempts = 0;
 191}
 192
 193static void
 194minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
 195{
 196        u8 tmp_tp_rate[MAX_THR_RATES];
 197        u8 tmp_prob_rate = 0;
 198        int i, tmp_cur_tp, tmp_prob_tp;
 199
 200        for (i = 0; i < MAX_THR_RATES; i++)
 201            tmp_tp_rate[i] = 0;
 202
 203        for (i = 0; i < mi->n_rates; i++) {
 204                struct minstrel_rate *mr = &mi->r[i];
 205                struct minstrel_rate_stats *mrs = &mi->r[i].stats;
 206                struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
 207
 208                /* Update statistics of success probability per rate */
 209                minstrel_calc_rate_stats(mrs);
 210
 211                /* Sample less often below the 10% chance of success.
 212                 * Sample less often above the 95% chance of success. */
 213                if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
 214                    mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
 215                        mr->adjusted_retry_count = mrs->retry_count >> 1;
 216                        if (mr->adjusted_retry_count > 2)
 217                                mr->adjusted_retry_count = 2;
 218                        mr->sample_limit = 4;
 219                } else {
 220                        mr->sample_limit = -1;
 221                        mr->adjusted_retry_count = mrs->retry_count;
 222                }
 223                if (!mr->adjusted_retry_count)
 224                        mr->adjusted_retry_count = 2;
 225
 226                minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
 227
 228                /* To determine the most robust rate (max_prob_rate) used at
 229                 * 3rd mmr stage we distinct between two cases:
 230                 * (1) if any success probabilitiy >= 95%, out of those rates
 231                 * choose the maximum throughput rate as max_prob_rate
 232                 * (2) if all success probabilities < 95%, the rate with
 233                 * highest success probability is chosen as max_prob_rate */
 234                if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
 235                        tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
 236                        tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
 237                                                          tmp_mrs->prob_ewma);
 238                        if (tmp_cur_tp >= tmp_prob_tp)
 239                                tmp_prob_rate = i;
 240                } else {
 241                        if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
 242                                tmp_prob_rate = i;
 243                }
 244        }
 245
 246        /* Assign the new rate set */
 247        memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
 248        mi->max_prob_rate = tmp_prob_rate;
 249
 250#ifdef CONFIG_MAC80211_DEBUGFS
 251        /* use fixed index if set */
 252        if (mp->fixed_rate_idx != -1) {
 253                mi->max_tp_rate[0] = mp->fixed_rate_idx;
 254                mi->max_tp_rate[1] = mp->fixed_rate_idx;
 255                mi->max_prob_rate = mp->fixed_rate_idx;
 256        }
 257#endif
 258
 259        /* Reset update timer */
 260        mi->last_stats_update = jiffies;
 261
 262        minstrel_update_rates(mp, mi);
 263}
 264
 265static void
 266minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
 267                   void *priv_sta, struct ieee80211_tx_status *st)
 268{
 269        struct ieee80211_tx_info *info = st->info;
 270        struct minstrel_priv *mp = priv;
 271        struct minstrel_sta_info *mi = priv_sta;
 272        struct ieee80211_tx_rate *ar = info->status.rates;
 273        int i, ndx;
 274        int success;
 275
 276        success = !!(info->flags & IEEE80211_TX_STAT_ACK);
 277
 278        for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 279                if (ar[i].idx < 0)
 280                        break;
 281
 282                ndx = rix_to_ndx(mi, ar[i].idx);
 283                if (ndx < 0)
 284                        continue;
 285
 286                mi->r[ndx].stats.attempts += ar[i].count;
 287
 288                if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
 289                        mi->r[ndx].stats.success += success;
 290        }
 291
 292        if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
 293                mi->sample_packets++;
 294
 295        if (mi->sample_deferred > 0)
 296                mi->sample_deferred--;
 297
 298        if (time_after(jiffies, mi->last_stats_update +
 299                                (mp->update_interval * HZ) / 1000))
 300                minstrel_update_stats(mp, mi);
 301}
 302
 303
 304static inline unsigned int
 305minstrel_get_retry_count(struct minstrel_rate *mr,
 306                         struct ieee80211_tx_info *info)
 307{
 308        u8 retry = mr->adjusted_retry_count;
 309
 310        if (info->control.use_rts)
 311                retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
 312        else if (info->control.use_cts_prot)
 313                retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
 314        return retry;
 315}
 316
 317
 318static int
 319minstrel_get_next_sample(struct minstrel_sta_info *mi)
 320{
 321        unsigned int sample_ndx;
 322        sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
 323        mi->sample_row++;
 324        if ((int) mi->sample_row >= mi->n_rates) {
 325                mi->sample_row = 0;
 326                mi->sample_column++;
 327                if (mi->sample_column >= SAMPLE_COLUMNS)
 328                        mi->sample_column = 0;
 329        }
 330        return sample_ndx;
 331}
 332
 333static void
 334minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
 335                  void *priv_sta, struct ieee80211_tx_rate_control *txrc)
 336{
 337        struct sk_buff *skb = txrc->skb;
 338        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 339        struct minstrel_sta_info *mi = priv_sta;
 340        struct minstrel_priv *mp = priv;
 341        struct ieee80211_tx_rate *rate = &info->control.rates[0];
 342        struct minstrel_rate *msr, *mr;
 343        unsigned int ndx;
 344        bool mrr_capable;
 345        bool prev_sample;
 346        int delta;
 347        int sampling_ratio;
 348
 349        /* management/no-ack frames do not use rate control */
 350        if (rate_control_send_low(sta, priv_sta, txrc))
 351                return;
 352
 353        /* check multi-rate-retry capabilities & adjust lookaround_rate */
 354        mrr_capable = mp->has_mrr &&
 355                      !txrc->rts &&
 356                      !txrc->bss_conf->use_cts_prot;
 357        if (mrr_capable)
 358                sampling_ratio = mp->lookaround_rate_mrr;
 359        else
 360                sampling_ratio = mp->lookaround_rate;
 361
 362        /* increase sum packet counter */
 363        mi->total_packets++;
 364
 365#ifdef CONFIG_MAC80211_DEBUGFS
 366        if (mp->fixed_rate_idx != -1)
 367                return;
 368#endif
 369
 370        /* Don't use EAPOL frames for sampling on non-mrr hw */
 371        if (mp->hw->max_rates == 1 &&
 372            (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
 373                return;
 374
 375        delta = (mi->total_packets * sampling_ratio / 100) -
 376                        (mi->sample_packets + mi->sample_deferred / 2);
 377
 378        /* delta < 0: no sampling required */
 379        prev_sample = mi->prev_sample;
 380        mi->prev_sample = false;
 381        if (delta < 0 || (!mrr_capable && prev_sample))
 382                return;
 383
 384        if (mi->total_packets >= 10000) {
 385                mi->sample_deferred = 0;
 386                mi->sample_packets = 0;
 387                mi->total_packets = 0;
 388        } else if (delta > mi->n_rates * 2) {
 389                /* With multi-rate retry, not every planned sample
 390                 * attempt actually gets used, due to the way the retry
 391                 * chain is set up - [max_tp,sample,prob,lowest] for
 392                 * sample_rate < max_tp.
 393                 *
 394                 * If there's too much sampling backlog and the link
 395                 * starts getting worse, minstrel would start bursting
 396                 * out lots of sampling frames, which would result
 397                 * in a large throughput loss. */
 398                mi->sample_packets += (delta - mi->n_rates * 2);
 399        }
 400
 401        /* get next random rate sample */
 402        ndx = minstrel_get_next_sample(mi);
 403        msr = &mi->r[ndx];
 404        mr = &mi->r[mi->max_tp_rate[0]];
 405
 406        /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
 407         * rate sampling method should be used.
 408         * Respect such rates that are not sampled for 20 interations.
 409         */
 410        if (mrr_capable &&
 411            msr->perfect_tx_time > mr->perfect_tx_time &&
 412            msr->stats.sample_skipped < 20) {
 413                /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
 414                 * packets that have the sampling rate deferred to the
 415                 * second MRR stage. Increase the sample counter only
 416                 * if the deferred sample rate was actually used.
 417                 * Use the sample_deferred counter to make sure that
 418                 * the sampling is not done in large bursts */
 419                info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
 420                rate++;
 421                mi->sample_deferred++;
 422        } else {
 423                if (!msr->sample_limit)
 424                        return;
 425
 426                mi->sample_packets++;
 427                if (msr->sample_limit > 0)
 428                        msr->sample_limit--;
 429        }
 430
 431        /* If we're not using MRR and the sampling rate already
 432         * has a probability of >95%, we shouldn't be attempting
 433         * to use it, as this only wastes precious airtime */
 434        if (!mrr_capable &&
 435           (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
 436                return;
 437
 438        mi->prev_sample = true;
 439
 440        rate->idx = mi->r[ndx].rix;
 441        rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
 442}
 443
 444
 445static void
 446calc_rate_durations(enum nl80211_band band,
 447                    struct minstrel_rate *d,
 448                    struct ieee80211_rate *rate,
 449                    struct cfg80211_chan_def *chandef)
 450{
 451        int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
 452        int shift = ieee80211_chandef_get_shift(chandef);
 453
 454        d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
 455                        DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
 456                        shift);
 457        d->ack_time = ieee80211_frame_duration(band, 10,
 458                        DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
 459                        shift);
 460}
 461
 462static void
 463init_sample_table(struct minstrel_sta_info *mi)
 464{
 465        unsigned int i, col, new_idx;
 466        u8 rnd[8];
 467
 468        mi->sample_column = 0;
 469        mi->sample_row = 0;
 470        memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
 471
 472        for (col = 0; col < SAMPLE_COLUMNS; col++) {
 473                prandom_bytes(rnd, sizeof(rnd));
 474                for (i = 0; i < mi->n_rates; i++) {
 475                        new_idx = (i + rnd[i & 7]) % mi->n_rates;
 476                        while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
 477                                new_idx = (new_idx + 1) % mi->n_rates;
 478
 479                        SAMPLE_TBL(mi, new_idx, col) = i;
 480                }
 481        }
 482}
 483
 484static void
 485minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
 486                   struct cfg80211_chan_def *chandef,
 487                   struct ieee80211_sta *sta, void *priv_sta)
 488{
 489        struct minstrel_sta_info *mi = priv_sta;
 490        struct minstrel_priv *mp = priv;
 491        struct ieee80211_rate *ctl_rate;
 492        unsigned int i, n = 0;
 493        unsigned int t_slot = 9; /* FIXME: get real slot time */
 494        u32 rate_flags;
 495
 496        mi->sta = sta;
 497        mi->lowest_rix = rate_lowest_index(sband, sta);
 498        ctl_rate = &sband->bitrates[mi->lowest_rix];
 499        mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
 500                                ctl_rate->bitrate,
 501                                !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
 502                                ieee80211_chandef_get_shift(chandef));
 503
 504        rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
 505        memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
 506        mi->max_prob_rate = 0;
 507
 508        for (i = 0; i < sband->n_bitrates; i++) {
 509                struct minstrel_rate *mr = &mi->r[n];
 510                struct minstrel_rate_stats *mrs = &mi->r[n].stats;
 511                unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
 512                unsigned int tx_time_single;
 513                unsigned int cw = mp->cw_min;
 514                int shift;
 515
 516                if (!rate_supported(sta, sband->band, i))
 517                        continue;
 518                if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
 519                        continue;
 520
 521                n++;
 522                memset(mr, 0, sizeof(*mr));
 523                memset(mrs, 0, sizeof(*mrs));
 524
 525                mr->rix = i;
 526                shift = ieee80211_chandef_get_shift(chandef);
 527                mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
 528                                           (1 << shift) * 5);
 529                calc_rate_durations(sband->band, mr, &sband->bitrates[i],
 530                                    chandef);
 531
 532                /* calculate maximum number of retransmissions before
 533                 * fallback (based on maximum segment size) */
 534                mr->sample_limit = -1;
 535                mrs->retry_count = 1;
 536                mr->retry_count_cts = 1;
 537                mrs->retry_count_rtscts = 1;
 538                tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
 539                do {
 540                        /* add one retransmission */
 541                        tx_time_single = mr->ack_time + mr->perfect_tx_time;
 542
 543                        /* contention window */
 544                        tx_time_single += (t_slot * cw) >> 1;
 545                        cw = min((cw << 1) | 1, mp->cw_max);
 546
 547                        tx_time += tx_time_single;
 548                        tx_time_cts += tx_time_single + mi->sp_ack_dur;
 549                        tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
 550                        if ((tx_time_cts < mp->segment_size) &&
 551                                (mr->retry_count_cts < mp->max_retry))
 552                                mr->retry_count_cts++;
 553                        if ((tx_time_rtscts < mp->segment_size) &&
 554                                (mrs->retry_count_rtscts < mp->max_retry))
 555                                mrs->retry_count_rtscts++;
 556                } while ((tx_time < mp->segment_size) &&
 557                                (++mr->stats.retry_count < mp->max_retry));
 558                mr->adjusted_retry_count = mrs->retry_count;
 559                if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
 560                        mr->retry_count_cts = mrs->retry_count;
 561        }
 562
 563        for (i = n; i < sband->n_bitrates; i++) {
 564                struct minstrel_rate *mr = &mi->r[i];
 565                mr->rix = -1;
 566        }
 567
 568        mi->n_rates = n;
 569        mi->last_stats_update = jiffies;
 570
 571        init_sample_table(mi);
 572        minstrel_update_rates(mp, mi);
 573}
 574
 575static void *
 576minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
 577{
 578        struct ieee80211_supported_band *sband;
 579        struct minstrel_sta_info *mi;
 580        struct minstrel_priv *mp = priv;
 581        struct ieee80211_hw *hw = mp->hw;
 582        int max_rates = 0;
 583        int i;
 584
 585        mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
 586        if (!mi)
 587                return NULL;
 588
 589        for (i = 0; i < NUM_NL80211_BANDS; i++) {
 590                sband = hw->wiphy->bands[i];
 591                if (sband && sband->n_bitrates > max_rates)
 592                        max_rates = sband->n_bitrates;
 593        }
 594
 595        mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
 596        if (!mi->r)
 597                goto error;
 598
 599        mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
 600        if (!mi->sample_table)
 601                goto error1;
 602
 603        mi->last_stats_update = jiffies;
 604        return mi;
 605
 606error1:
 607        kfree(mi->r);
 608error:
 609        kfree(mi);
 610        return NULL;
 611}
 612
 613static void
 614minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
 615{
 616        struct minstrel_sta_info *mi = priv_sta;
 617
 618        kfree(mi->sample_table);
 619        kfree(mi->r);
 620        kfree(mi);
 621}
 622
 623static void
 624minstrel_init_cck_rates(struct minstrel_priv *mp)
 625{
 626        static const int bitrates[4] = { 10, 20, 55, 110 };
 627        struct ieee80211_supported_band *sband;
 628        u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
 629        int i, j;
 630
 631        sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
 632        if (!sband)
 633                return;
 634
 635        for (i = 0, j = 0; i < sband->n_bitrates; i++) {
 636                struct ieee80211_rate *rate = &sband->bitrates[i];
 637
 638                if (rate->flags & IEEE80211_RATE_ERP_G)
 639                        continue;
 640
 641                if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
 642                        continue;
 643
 644                for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
 645                        if (rate->bitrate != bitrates[j])
 646                                continue;
 647
 648                        mp->cck_rates[j] = i;
 649                        break;
 650                }
 651        }
 652}
 653
 654static void *
 655minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
 656{
 657        struct minstrel_priv *mp;
 658
 659        mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
 660        if (!mp)
 661                return NULL;
 662
 663        /* contention window settings
 664         * Just an approximation. Using the per-queue values would complicate
 665         * the calculations and is probably unnecessary */
 666        mp->cw_min = 15;
 667        mp->cw_max = 1023;
 668
 669        /* number of packets (in %) to use for sampling other rates
 670         * sample less often for non-mrr packets, because the overhead
 671         * is much higher than with mrr */
 672        mp->lookaround_rate = 5;
 673        mp->lookaround_rate_mrr = 10;
 674
 675        /* maximum time that the hw is allowed to stay in one MRR segment */
 676        mp->segment_size = 6000;
 677
 678        if (hw->max_rate_tries > 0)
 679                mp->max_retry = hw->max_rate_tries;
 680        else
 681                /* safe default, does not necessarily have to match hw properties */
 682                mp->max_retry = 7;
 683
 684        if (hw->max_rates >= 4)
 685                mp->has_mrr = true;
 686
 687        mp->hw = hw;
 688        mp->update_interval = 100;
 689
 690#ifdef CONFIG_MAC80211_DEBUGFS
 691        mp->fixed_rate_idx = (u32) -1;
 692        mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
 693                        S_IRUGO | S_IWUGO, debugfsdir, &mp->fixed_rate_idx);
 694#endif
 695
 696        minstrel_init_cck_rates(mp);
 697
 698        return mp;
 699}
 700
 701static void
 702minstrel_free(void *priv)
 703{
 704#ifdef CONFIG_MAC80211_DEBUGFS
 705        debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
 706#endif
 707        kfree(priv);
 708}
 709
 710static u32 minstrel_get_expected_throughput(void *priv_sta)
 711{
 712        struct minstrel_sta_info *mi = priv_sta;
 713        struct minstrel_rate_stats *tmp_mrs;
 714        int idx = mi->max_tp_rate[0];
 715        int tmp_cur_tp;
 716
 717        /* convert pkt per sec in kbps (1200 is the average pkt size used for
 718         * computing cur_tp
 719         */
 720        tmp_mrs = &mi->r[idx].stats;
 721        tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
 722        tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
 723
 724        return tmp_cur_tp;
 725}
 726
 727const struct rate_control_ops mac80211_minstrel = {
 728        .name = "minstrel",
 729        .tx_status_ext = minstrel_tx_status,
 730        .get_rate = minstrel_get_rate,
 731        .rate_init = minstrel_rate_init,
 732        .alloc = minstrel_alloc,
 733        .free = minstrel_free,
 734        .alloc_sta = minstrel_alloc_sta,
 735        .free_sta = minstrel_free_sta,
 736#ifdef CONFIG_MAC80211_DEBUGFS
 737        .add_sta_debugfs = minstrel_add_sta_debugfs,
 738        .remove_sta_debugfs = minstrel_remove_sta_debugfs,
 739#endif
 740        .get_expected_throughput = minstrel_get_expected_throughput,
 741};
 742
 743int __init
 744rc80211_minstrel_init(void)
 745{
 746        return ieee80211_rate_control_register(&mac80211_minstrel);
 747}
 748
 749void
 750rc80211_minstrel_exit(void)
 751{
 752        ieee80211_rate_control_unregister(&mac80211_minstrel);
 753}
 754
 755