linux/net/mac80211/rc80211_minstrel_ht.c
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   1/*
   2 * Copyright (C) 2010 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#include <linux/netdevice.h>
   9#include <linux/types.h>
  10#include <linux/skbuff.h>
  11#include <linux/debugfs.h>
  12#include <linux/random.h>
  13#include <linux/ieee80211.h>
  14#include <net/mac80211.h>
  15#include "rate.h"
  16#include "rc80211_minstrel.h"
  17#include "rc80211_minstrel_ht.h"
  18
  19#define AVG_PKT_SIZE    1200
  20#define SAMPLE_COLUMNS  10
  21#define EWMA_LEVEL              75
  22
  23/* Number of bits for an average sized packet */
  24#define MCS_NBITS (AVG_PKT_SIZE << 3)
  25
  26/* Number of symbols for a packet with (bps) bits per symbol */
  27#define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
  28
  29/* Transmission time for a packet containing (syms) symbols */
  30#define MCS_SYMBOL_TIME(sgi, syms)                                      \
  31        (sgi ?                                                          \
  32          ((syms) * 18 + 4) / 5 :       /* syms * 3.6 us */             \
  33          (syms) << 2                   /* syms * 4 us */               \
  34        )
  35
  36/* Transmit duration for the raw data part of an average sized packet */
  37#define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
  38
  39/*
  40 * Define group sort order: HT40 -> SGI -> #streams
  41 */
  42#define GROUP_IDX(_streams, _sgi, _ht40)        \
  43        MINSTREL_MAX_STREAMS * 2 * _ht40 +      \
  44        MINSTREL_MAX_STREAMS * _sgi +           \
  45        _streams - 1
  46
  47/* MCS rate information for an MCS group */
  48#define MCS_GROUP(_streams, _sgi, _ht40)                                \
  49        [GROUP_IDX(_streams, _sgi, _ht40)] = {                          \
  50        .streams = _streams,                                            \
  51        .flags =                                                        \
  52                (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |                 \
  53                (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),             \
  54        .duration = {                                                   \
  55                MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26),          \
  56                MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52),         \
  57                MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78),         \
  58                MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104),        \
  59                MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156),        \
  60                MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208),        \
  61                MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234),        \
  62                MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260)         \
  63        }                                                               \
  64}
  65
  66/*
  67 * To enable sufficiently targeted rate sampling, MCS rates are divided into
  68 * groups, based on the number of streams and flags (HT40, SGI) that they
  69 * use.
  70 *
  71 * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
  72 * HT40 -> SGI -> #streams
  73 */
  74const struct mcs_group minstrel_mcs_groups[] = {
  75        MCS_GROUP(1, 0, 0),
  76        MCS_GROUP(2, 0, 0),
  77#if MINSTREL_MAX_STREAMS >= 3
  78        MCS_GROUP(3, 0, 0),
  79#endif
  80
  81        MCS_GROUP(1, 1, 0),
  82        MCS_GROUP(2, 1, 0),
  83#if MINSTREL_MAX_STREAMS >= 3
  84        MCS_GROUP(3, 1, 0),
  85#endif
  86
  87        MCS_GROUP(1, 0, 1),
  88        MCS_GROUP(2, 0, 1),
  89#if MINSTREL_MAX_STREAMS >= 3
  90        MCS_GROUP(3, 0, 1),
  91#endif
  92
  93        MCS_GROUP(1, 1, 1),
  94        MCS_GROUP(2, 1, 1),
  95#if MINSTREL_MAX_STREAMS >= 3
  96        MCS_GROUP(3, 1, 1),
  97#endif
  98};
  99
 100static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
 101
 102/*
 103 * Perform EWMA (Exponentially Weighted Moving Average) calculation
 104 */
 105static int
 106minstrel_ewma(int old, int new, int weight)
 107{
 108        return (new * (100 - weight) + old * weight) / 100;
 109}
 110
 111/*
 112 * Look up an MCS group index based on mac80211 rate information
 113 */
 114static int
 115minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
 116{
 117        return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
 118                         !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
 119                         !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
 120}
 121
 122static inline struct minstrel_rate_stats *
 123minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
 124{
 125        return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
 126}
 127
 128
 129/*
 130 * Recalculate success probabilities and counters for a rate using EWMA
 131 */
 132static void
 133minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
 134{
 135        if (unlikely(mr->attempts > 0)) {
 136                mr->sample_skipped = 0;
 137                mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
 138                if (!mr->att_hist)
 139                        mr->probability = mr->cur_prob;
 140                else
 141                        mr->probability = minstrel_ewma(mr->probability,
 142                                mr->cur_prob, EWMA_LEVEL);
 143                mr->att_hist += mr->attempts;
 144                mr->succ_hist += mr->success;
 145        } else {
 146                mr->sample_skipped++;
 147        }
 148        mr->last_success = mr->success;
 149        mr->last_attempts = mr->attempts;
 150        mr->success = 0;
 151        mr->attempts = 0;
 152}
 153
 154/*
 155 * Calculate throughput based on the average A-MPDU length, taking into account
 156 * the expected number of retransmissions and their expected length
 157 */
 158static void
 159minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
 160{
 161        struct minstrel_rate_stats *mr;
 162        unsigned int usecs;
 163
 164        mr = &mi->groups[group].rates[rate];
 165
 166        if (mr->probability < MINSTREL_FRAC(1, 10)) {
 167                mr->cur_tp = 0;
 168                return;
 169        }
 170
 171        usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
 172        usecs += minstrel_mcs_groups[group].duration[rate];
 173        mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
 174}
 175
 176/*
 177 * Update rate statistics and select new primary rates
 178 *
 179 * Rules for rate selection:
 180 *  - max_prob_rate must use only one stream, as a tradeoff between delivery
 181 *    probability and throughput during strong fluctuations
 182 *  - as long as the max prob rate has a probability of more than 3/4, pick
 183 *    higher throughput rates, even if the probablity is a bit lower
 184 */
 185static void
 186minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 187{
 188        struct minstrel_mcs_group_data *mg;
 189        struct minstrel_rate_stats *mr;
 190        int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
 191        int group, i, index;
 192
 193        if (mi->ampdu_packets > 0) {
 194                mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
 195                        MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
 196                mi->ampdu_len = 0;
 197                mi->ampdu_packets = 0;
 198        }
 199
 200        mi->sample_slow = 0;
 201        mi->sample_count = 0;
 202        mi->max_tp_rate = 0;
 203        mi->max_tp_rate2 = 0;
 204        mi->max_prob_rate = 0;
 205
 206        for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
 207                cur_prob = 0;
 208                cur_prob_tp = 0;
 209                cur_tp = 0;
 210                cur_tp2 = 0;
 211
 212                mg = &mi->groups[group];
 213                if (!mg->supported)
 214                        continue;
 215
 216                mg->max_tp_rate = 0;
 217                mg->max_tp_rate2 = 0;
 218                mg->max_prob_rate = 0;
 219                mi->sample_count++;
 220
 221                for (i = 0; i < MCS_GROUP_RATES; i++) {
 222                        if (!(mg->supported & BIT(i)))
 223                                continue;
 224
 225                        mr = &mg->rates[i];
 226                        mr->retry_updated = false;
 227                        index = MCS_GROUP_RATES * group + i;
 228                        minstrel_calc_rate_ewma(mr);
 229                        minstrel_ht_calc_tp(mi, group, i);
 230
 231                        if (!mr->cur_tp)
 232                                continue;
 233
 234                        /* ignore the lowest rate of each single-stream group */
 235                        if (!i && minstrel_mcs_groups[group].streams == 1)
 236                                continue;
 237
 238                        if ((mr->cur_tp > cur_prob_tp && mr->probability >
 239                             MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
 240                                mg->max_prob_rate = index;
 241                                cur_prob = mr->probability;
 242                                cur_prob_tp = mr->cur_tp;
 243                        }
 244
 245                        if (mr->cur_tp > cur_tp) {
 246                                swap(index, mg->max_tp_rate);
 247                                cur_tp = mr->cur_tp;
 248                                mr = minstrel_get_ratestats(mi, index);
 249                        }
 250
 251                        if (index >= mg->max_tp_rate)
 252                                continue;
 253
 254                        if (mr->cur_tp > cur_tp2) {
 255                                mg->max_tp_rate2 = index;
 256                                cur_tp2 = mr->cur_tp;
 257                        }
 258                }
 259        }
 260
 261        /* try to sample up to half of the available rates during each interval */
 262        mi->sample_count *= 4;
 263
 264        cur_prob = 0;
 265        cur_prob_tp = 0;
 266        cur_tp = 0;
 267        cur_tp2 = 0;
 268        for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
 269                mg = &mi->groups[group];
 270                if (!mg->supported)
 271                        continue;
 272
 273                mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
 274                if (cur_prob_tp < mr->cur_tp &&
 275                    minstrel_mcs_groups[group].streams == 1) {
 276                        mi->max_prob_rate = mg->max_prob_rate;
 277                        cur_prob = mr->cur_prob;
 278                        cur_prob_tp = mr->cur_tp;
 279                }
 280
 281                mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
 282                if (cur_tp < mr->cur_tp) {
 283                        mi->max_tp_rate2 = mi->max_tp_rate;
 284                        cur_tp2 = cur_tp;
 285                        mi->max_tp_rate = mg->max_tp_rate;
 286                        cur_tp = mr->cur_tp;
 287                }
 288
 289                mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
 290                if (cur_tp2 < mr->cur_tp) {
 291                        mi->max_tp_rate2 = mg->max_tp_rate2;
 292                        cur_tp2 = mr->cur_tp;
 293                }
 294        }
 295
 296        mi->stats_update = jiffies;
 297}
 298
 299static bool
 300minstrel_ht_txstat_valid(struct ieee80211_tx_rate *rate)
 301{
 302        if (rate->idx < 0)
 303                return false;
 304
 305        if (!rate->count)
 306                return false;
 307
 308        return !!(rate->flags & IEEE80211_TX_RC_MCS);
 309}
 310
 311static void
 312minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
 313{
 314        struct minstrel_mcs_group_data *mg;
 315
 316        for (;;) {
 317                mi->sample_group++;
 318                mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
 319                mg = &mi->groups[mi->sample_group];
 320
 321                if (!mg->supported)
 322                        continue;
 323
 324                if (++mg->index >= MCS_GROUP_RATES) {
 325                        mg->index = 0;
 326                        if (++mg->column >= ARRAY_SIZE(sample_table))
 327                                mg->column = 0;
 328                }
 329                break;
 330        }
 331}
 332
 333static void
 334minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
 335                        bool primary)
 336{
 337        int group, orig_group;
 338
 339        orig_group = group = *idx / MCS_GROUP_RATES;
 340        while (group > 0) {
 341                group--;
 342
 343                if (!mi->groups[group].supported)
 344                        continue;
 345
 346                if (minstrel_mcs_groups[group].streams >
 347                    minstrel_mcs_groups[orig_group].streams)
 348                        continue;
 349
 350                if (primary)
 351                        *idx = mi->groups[group].max_tp_rate;
 352                else
 353                        *idx = mi->groups[group].max_tp_rate2;
 354                break;
 355        }
 356}
 357
 358static void
 359minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
 360{
 361        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 362        struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
 363        u16 tid;
 364
 365        if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
 366                return;
 367
 368        if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
 369                return;
 370
 371        tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 372        if (likely(sta->ampdu_mlme.tid_tx[tid]))
 373                return;
 374
 375        if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
 376                return;
 377
 378        ieee80211_start_tx_ba_session(pubsta, tid, 5000);
 379}
 380
 381static void
 382minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 383                      struct ieee80211_sta *sta, void *priv_sta,
 384                      struct sk_buff *skb)
 385{
 386        struct minstrel_ht_sta_priv *msp = priv_sta;
 387        struct minstrel_ht_sta *mi = &msp->ht;
 388        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 389        struct ieee80211_tx_rate *ar = info->status.rates;
 390        struct minstrel_rate_stats *rate, *rate2;
 391        struct minstrel_priv *mp = priv;
 392        bool last = false;
 393        int group;
 394        int i = 0;
 395
 396        if (!msp->is_ht)
 397                return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
 398
 399        /* This packet was aggregated but doesn't carry status info */
 400        if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
 401            !(info->flags & IEEE80211_TX_STAT_AMPDU))
 402                return;
 403
 404        if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
 405                info->status.ampdu_ack_len =
 406                        (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
 407                info->status.ampdu_len = 1;
 408        }
 409
 410        mi->ampdu_packets++;
 411        mi->ampdu_len += info->status.ampdu_len;
 412
 413        if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
 414                mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
 415                mi->sample_tries = 2;
 416                mi->sample_count--;
 417        }
 418
 419        if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
 420                mi->sample_packets += info->status.ampdu_len;
 421
 422        for (i = 0; !last; i++) {
 423                last = (i == IEEE80211_TX_MAX_RATES - 1) ||
 424                       !minstrel_ht_txstat_valid(&ar[i + 1]);
 425
 426                if (!minstrel_ht_txstat_valid(&ar[i]))
 427                        break;
 428
 429                group = minstrel_ht_get_group_idx(&ar[i]);
 430                rate = &mi->groups[group].rates[ar[i].idx % 8];
 431
 432                if (last)
 433                        rate->success += info->status.ampdu_ack_len;
 434
 435                rate->attempts += ar[i].count * info->status.ampdu_len;
 436        }
 437
 438        /*
 439         * check for sudden death of spatial multiplexing,
 440         * downgrade to a lower number of streams if necessary.
 441         */
 442        rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
 443        if (rate->attempts > 30 &&
 444            MINSTREL_FRAC(rate->success, rate->attempts) <
 445            MINSTREL_FRAC(20, 100))
 446                minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
 447
 448        rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
 449        if (rate2->attempts > 30 &&
 450            MINSTREL_FRAC(rate2->success, rate2->attempts) <
 451            MINSTREL_FRAC(20, 100))
 452                minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
 453
 454        if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
 455                minstrel_ht_update_stats(mp, mi);
 456                if (!(info->flags & IEEE80211_TX_CTL_AMPDU))
 457                        minstrel_aggr_check(sta, skb);
 458        }
 459}
 460
 461static void
 462minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 463                         int index)
 464{
 465        struct minstrel_rate_stats *mr;
 466        const struct mcs_group *group;
 467        unsigned int tx_time, tx_time_rtscts, tx_time_data;
 468        unsigned int cw = mp->cw_min;
 469        unsigned int ctime = 0;
 470        unsigned int t_slot = 9; /* FIXME */
 471        unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
 472
 473        mr = minstrel_get_ratestats(mi, index);
 474        if (mr->probability < MINSTREL_FRAC(1, 10)) {
 475                mr->retry_count = 1;
 476                mr->retry_count_rtscts = 1;
 477                return;
 478        }
 479
 480        mr->retry_count = 2;
 481        mr->retry_count_rtscts = 2;
 482        mr->retry_updated = true;
 483
 484        group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
 485        tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len;
 486
 487        /* Contention time for first 2 tries */
 488        ctime = (t_slot * cw) >> 1;
 489        cw = min((cw << 1) | 1, mp->cw_max);
 490        ctime += (t_slot * cw) >> 1;
 491        cw = min((cw << 1) | 1, mp->cw_max);
 492
 493        /* Total TX time for data and Contention after first 2 tries */
 494        tx_time = ctime + 2 * (mi->overhead + tx_time_data);
 495        tx_time_rtscts = ctime + 2 * (mi->overhead_rtscts + tx_time_data);
 496
 497        /* See how many more tries we can fit inside segment size */
 498        do {
 499                /* Contention time for this try */
 500                ctime = (t_slot * cw) >> 1;
 501                cw = min((cw << 1) | 1, mp->cw_max);
 502
 503                /* Total TX time after this try */
 504                tx_time += ctime + mi->overhead + tx_time_data;
 505                tx_time_rtscts += ctime + mi->overhead_rtscts + tx_time_data;
 506
 507                if (tx_time_rtscts < mp->segment_size)
 508                        mr->retry_count_rtscts++;
 509        } while ((tx_time < mp->segment_size) &&
 510                 (++mr->retry_count < mp->max_retry));
 511}
 512
 513
 514static void
 515minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 516                     struct ieee80211_tx_rate *rate, int index,
 517                     bool sample, bool rtscts)
 518{
 519        const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
 520        struct minstrel_rate_stats *mr;
 521
 522        mr = minstrel_get_ratestats(mi, index);
 523        if (!mr->retry_updated)
 524                minstrel_calc_retransmit(mp, mi, index);
 525
 526        if (sample)
 527                rate->count = 1;
 528        else if (mr->probability < MINSTREL_FRAC(20, 100))
 529                rate->count = 2;
 530        else if (rtscts)
 531                rate->count = mr->retry_count_rtscts;
 532        else
 533                rate->count = mr->retry_count;
 534
 535        rate->flags = IEEE80211_TX_RC_MCS | group->flags;
 536        if (rtscts)
 537                rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
 538        rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
 539}
 540
 541static inline int
 542minstrel_get_duration(int index)
 543{
 544        const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
 545        return group->duration[index % MCS_GROUP_RATES];
 546}
 547
 548static int
 549minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 550{
 551        struct minstrel_rate_stats *mr;
 552        struct minstrel_mcs_group_data *mg;
 553        int sample_idx = 0;
 554
 555        if (mi->sample_wait > 0) {
 556                mi->sample_wait--;
 557                return -1;
 558        }
 559
 560        if (!mi->sample_tries)
 561                return -1;
 562
 563        mi->sample_tries--;
 564        mg = &mi->groups[mi->sample_group];
 565        sample_idx = sample_table[mg->column][mg->index];
 566        mr = &mg->rates[sample_idx];
 567        sample_idx += mi->sample_group * MCS_GROUP_RATES;
 568        minstrel_next_sample_idx(mi);
 569
 570        /*
 571         * Sampling might add some overhead (RTS, no aggregation)
 572         * to the frame. Hence, don't use sampling for the currently
 573         * used max TP rate.
 574         */
 575        if (sample_idx == mi->max_tp_rate)
 576                return -1;
 577        /*
 578         * When not using MRR, do not sample if the probability is already
 579         * higher than 95% to avoid wasting airtime
 580         */
 581        if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
 582                return -1;
 583
 584        /*
 585         * Make sure that lower rates get sampled only occasionally,
 586         * if the link is working perfectly.
 587         */
 588        if (minstrel_get_duration(sample_idx) >
 589            minstrel_get_duration(mi->max_tp_rate)) {
 590                if (mr->sample_skipped < 20)
 591                        return -1;
 592
 593                if (mi->sample_slow++ > 2)
 594                        return -1;
 595        }
 596
 597        return sample_idx;
 598}
 599
 600static void
 601minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 602                     struct ieee80211_tx_rate_control *txrc)
 603{
 604        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 605        struct ieee80211_tx_rate *ar = info->status.rates;
 606        struct minstrel_ht_sta_priv *msp = priv_sta;
 607        struct minstrel_ht_sta *mi = &msp->ht;
 608        struct minstrel_priv *mp = priv;
 609        int sample_idx;
 610        bool sample = false;
 611
 612        if (rate_control_send_low(sta, priv_sta, txrc))
 613                return;
 614
 615        if (!msp->is_ht)
 616                return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
 617
 618        info->flags |= mi->tx_flags;
 619
 620        /* Don't use EAPOL frames for sampling on non-mrr hw */
 621        if (mp->hw->max_rates == 1 &&
 622            txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
 623                sample_idx = -1;
 624        else
 625                sample_idx = minstrel_get_sample_rate(mp, mi);
 626
 627#ifdef CONFIG_MAC80211_DEBUGFS
 628        /* use fixed index if set */
 629        if (mp->fixed_rate_idx != -1) {
 630                mi->max_tp_rate = mp->fixed_rate_idx;
 631                mi->max_tp_rate2 = mp->fixed_rate_idx;
 632                mi->max_prob_rate = mp->fixed_rate_idx;
 633                sample_idx = -1;
 634        }
 635#endif
 636
 637        if (sample_idx >= 0) {
 638                sample = true;
 639                minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
 640                        true, false);
 641                info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
 642        } else {
 643                minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
 644                        false, false);
 645        }
 646
 647        if (mp->hw->max_rates >= 3) {
 648                /*
 649                 * At least 3 tx rates supported, use
 650                 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
 651                 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
 652                 */
 653                if (sample_idx >= 0)
 654                        minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
 655                                false, false);
 656                else
 657                        minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
 658                                false, true);
 659
 660                minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
 661                                     false, !sample);
 662
 663                ar[3].count = 0;
 664                ar[3].idx = -1;
 665        } else if (mp->hw->max_rates == 2) {
 666                /*
 667                 * Only 2 tx rates supported, use
 668                 * sample_rate -> max_prob_rate for sampling and
 669                 * max_tp_rate -> max_prob_rate by default.
 670                 */
 671                minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
 672                                     false, !sample);
 673
 674                ar[2].count = 0;
 675                ar[2].idx = -1;
 676        } else {
 677                /* Not using MRR, only use the first rate */
 678                ar[1].count = 0;
 679                ar[1].idx = -1;
 680        }
 681
 682        mi->total_packets++;
 683
 684        /* wraparound */
 685        if (mi->total_packets == ~0) {
 686                mi->total_packets = 0;
 687                mi->sample_packets = 0;
 688        }
 689}
 690
 691static void
 692minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 693                        struct ieee80211_sta *sta, void *priv_sta)
 694{
 695        struct minstrel_priv *mp = priv;
 696        struct minstrel_ht_sta_priv *msp = priv_sta;
 697        struct minstrel_ht_sta *mi = &msp->ht;
 698        struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
 699        u16 sta_cap = sta->ht_cap.cap;
 700        int n_supported = 0;
 701        int ack_dur;
 702        int stbc;
 703        int i;
 704        unsigned int smps;
 705
 706        /* fall back to the old minstrel for legacy stations */
 707        if (!sta->ht_cap.ht_supported)
 708                goto use_legacy;
 709
 710        BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
 711                MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
 712
 713        msp->is_ht = true;
 714        memset(mi, 0, sizeof(*mi));
 715        mi->stats_update = jiffies;
 716
 717        ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
 718        mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
 719        mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
 720
 721        mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
 722
 723        /* When using MRR, sample more on the first attempt, without delay */
 724        if (mp->has_mrr) {
 725                mi->sample_count = 16;
 726                mi->sample_wait = 0;
 727        } else {
 728                mi->sample_count = 8;
 729                mi->sample_wait = 8;
 730        }
 731        mi->sample_tries = 4;
 732
 733        stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
 734                IEEE80211_HT_CAP_RX_STBC_SHIFT;
 735        mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
 736
 737        if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
 738                mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
 739
 740        smps = (sta_cap & IEEE80211_HT_CAP_SM_PS) >>
 741                IEEE80211_HT_CAP_SM_PS_SHIFT;
 742
 743        for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
 744                u16 req = 0;
 745
 746                mi->groups[i].supported = 0;
 747                if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
 748                        if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
 749                                req |= IEEE80211_HT_CAP_SGI_40;
 750                        else
 751                                req |= IEEE80211_HT_CAP_SGI_20;
 752                }
 753
 754                if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
 755                        req |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
 756
 757                if ((sta_cap & req) != req)
 758                        continue;
 759
 760                /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
 761                if (smps == WLAN_HT_CAP_SM_PS_STATIC &&
 762                    minstrel_mcs_groups[i].streams > 1)
 763                        continue;
 764
 765                mi->groups[i].supported =
 766                        mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
 767
 768                if (mi->groups[i].supported)
 769                        n_supported++;
 770        }
 771
 772        if (!n_supported)
 773                goto use_legacy;
 774
 775        return;
 776
 777use_legacy:
 778        msp->is_ht = false;
 779        memset(&msp->legacy, 0, sizeof(msp->legacy));
 780        msp->legacy.r = msp->ratelist;
 781        msp->legacy.sample_table = msp->sample_table;
 782        return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
 783}
 784
 785static void
 786minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
 787                      struct ieee80211_sta *sta, void *priv_sta)
 788{
 789        minstrel_ht_update_caps(priv, sband, sta, priv_sta);
 790}
 791
 792static void
 793minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
 794                        struct ieee80211_sta *sta, void *priv_sta,
 795                        u32 changed)
 796{
 797        minstrel_ht_update_caps(priv, sband, sta, priv_sta);
 798}
 799
 800static void *
 801minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
 802{
 803        struct ieee80211_supported_band *sband;
 804        struct minstrel_ht_sta_priv *msp;
 805        struct minstrel_priv *mp = priv;
 806        struct ieee80211_hw *hw = mp->hw;
 807        int max_rates = 0;
 808        int i;
 809
 810        for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 811                sband = hw->wiphy->bands[i];
 812                if (sband && sband->n_bitrates > max_rates)
 813                        max_rates = sband->n_bitrates;
 814        }
 815
 816        msp = kzalloc(sizeof(*msp), gfp);
 817        if (!msp)
 818                return NULL;
 819
 820        msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
 821        if (!msp->ratelist)
 822                goto error;
 823
 824        msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
 825        if (!msp->sample_table)
 826                goto error1;
 827
 828        return msp;
 829
 830error1:
 831        kfree(msp->ratelist);
 832error:
 833        kfree(msp);
 834        return NULL;
 835}
 836
 837static void
 838minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
 839{
 840        struct minstrel_ht_sta_priv *msp = priv_sta;
 841
 842        kfree(msp->sample_table);
 843        kfree(msp->ratelist);
 844        kfree(msp);
 845}
 846
 847static void *
 848minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
 849{
 850        return mac80211_minstrel.alloc(hw, debugfsdir);
 851}
 852
 853static void
 854minstrel_ht_free(void *priv)
 855{
 856        mac80211_minstrel.free(priv);
 857}
 858
 859static struct rate_control_ops mac80211_minstrel_ht = {
 860        .name = "minstrel_ht",
 861        .tx_status = minstrel_ht_tx_status,
 862        .get_rate = minstrel_ht_get_rate,
 863        .rate_init = minstrel_ht_rate_init,
 864        .rate_update = minstrel_ht_rate_update,
 865        .alloc_sta = minstrel_ht_alloc_sta,
 866        .free_sta = minstrel_ht_free_sta,
 867        .alloc = minstrel_ht_alloc,
 868        .free = minstrel_ht_free,
 869#ifdef CONFIG_MAC80211_DEBUGFS
 870        .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
 871        .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
 872#endif
 873};
 874
 875
 876static void
 877init_sample_table(void)
 878{
 879        int col, i, new_idx;
 880        u8 rnd[MCS_GROUP_RATES];
 881
 882        memset(sample_table, 0xff, sizeof(sample_table));
 883        for (col = 0; col < SAMPLE_COLUMNS; col++) {
 884                for (i = 0; i < MCS_GROUP_RATES; i++) {
 885                        get_random_bytes(rnd, sizeof(rnd));
 886                        new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
 887
 888                        while (sample_table[col][new_idx] != 0xff)
 889                                new_idx = (new_idx + 1) % MCS_GROUP_RATES;
 890
 891                        sample_table[col][new_idx] = i;
 892                }
 893        }
 894}
 895
 896int __init
 897rc80211_minstrel_ht_init(void)
 898{
 899        init_sample_table();
 900        return ieee80211_rate_control_register(&mac80211_minstrel_ht);
 901}
 902
 903void
 904rc80211_minstrel_ht_exit(void)
 905{
 906        ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
 907}
 908
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