net/mac80211/rc80211_minstrel_ht.c

   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  */
  74 const 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
 100 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
 101
 102 /*
 103  * Perform EWMA (Exponentially Weighted Moving Average) calculation
 104  */
 105 static int
 106 minstrel_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  */
 114 static int
 115 minstrel_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
 122 static inline struct minstrel_rate_stats *
 123 minstrel_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  */
 132 static void
 133 minstrel_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  */
 158 static void
 159 minstrel_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  */
 185 static void
 186 minstrel_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
 299 static bool
 300 minstrel_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
 311 static void
 312 minstrel_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
 333 static void
 334 minstrel_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
 358 static void
 359 minstrel_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
 381 static void
 382 minstrel_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;
 393         int group;
 394         int i;
 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         last = !minstrel_ht_txstat_valid(&ar[0]);
 423         for (i = 0; !last; i++) {
 424                 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
 425                        !minstrel_ht_txstat_valid(&ar[i + 1]);
 426
 427                 group = minstrel_ht_get_group_idx(&ar[i]);
 428                 rate = &mi->groups[group].rates[ar[i].idx % 8];
 429
 430                 if (last)
 431                         rate->success += info->status.ampdu_ack_len;
 432
 433                 rate->attempts += ar[i].count * info->status.ampdu_len;
 434         }
 435
 436         /*
 437          * check for sudden death of spatial multiplexing,
 438          * downgrade to a lower number of streams if necessary.
 439          */
 440         rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
 441         if (rate->attempts > 30 &&
 442             MINSTREL_FRAC(rate->success, rate->attempts) <
 443             MINSTREL_FRAC(20, 100))
 444                 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
 445
 446         rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
 447         if (rate2->attempts > 30 &&
 448             MINSTREL_FRAC(rate2->success, rate2->attempts) <
 449             MINSTREL_FRAC(20, 100))
 450                 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
 451
 452         if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
 453                 minstrel_ht_update_stats(mp, mi);
 454                 if (!(info->flags & IEEE80211_TX_CTL_AMPDU))
 455                         minstrel_aggr_check(sta, skb);
 456         }
 457 }
 458
 459 static void
 460 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 461                          int index)
 462 {
 463         struct minstrel_rate_stats *mr;
 464         const struct mcs_group *group;
 465         unsigned int tx_time, tx_time_rtscts, tx_time_data;
 466         unsigned int cw = mp->cw_min;
 467         unsigned int ctime = 0;
 468         unsigned int t_slot = 9; /* FIXME */
 469         unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
 470
 471         mr = minstrel_get_ratestats(mi, index);
 472         if (mr->probability < MINSTREL_FRAC(1, 10)) {
 473                 mr->retry_count = 1;
 474                 mr->retry_count_rtscts = 1;
 475                 return;
 476         }
 477
 478         mr->retry_count = 2;
 479         mr->retry_count_rtscts = 2;
 480         mr->retry_updated = true;
 481
 482         group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
 483         tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len;
 484
 485         /* Contention time for first 2 tries */
 486         ctime = (t_slot * cw) >> 1;
 487         cw = min((cw << 1) | 1, mp->cw_max);
 488         ctime += (t_slot * cw) >> 1;
 489         cw = min((cw << 1) | 1, mp->cw_max);
 490
 491         /* Total TX time for data and Contention after first 2 tries */
 492         tx_time = ctime + 2 * (mi->overhead + tx_time_data);
 493         tx_time_rtscts = ctime + 2 * (mi->overhead_rtscts + tx_time_data);
 494
 495         /* See how many more tries we can fit inside segment size */
 496         do {
 497                 /* Contention time for this try */
 498                 ctime = (t_slot * cw) >> 1;
 499                 cw = min((cw << 1) | 1, mp->cw_max);
 500
 501                 /* Total TX time after this try */
 502                 tx_time += ctime + mi->overhead + tx_time_data;
 503                 tx_time_rtscts += ctime + mi->overhead_rtscts + tx_time_data;
 504
 505                 if (tx_time_rtscts < mp->segment_size)
 506                         mr->retry_count_rtscts++;
 507         } while ((tx_time < mp->segment_size) &&
 508                  (++mr->retry_count < mp->max_retry));
 509 }
 510
 511
 512 static void
 513 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 514                      struct ieee80211_tx_rate *rate, int index,
 515                      bool sample, bool rtscts)
 516 {
 517         const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
 518         struct minstrel_rate_stats *mr;
 519
 520         mr = minstrel_get_ratestats(mi, index);
 521         if (!mr->retry_updated)
 522                 minstrel_calc_retransmit(mp, mi, index);
 523
 524         if (sample)
 525                 rate->count = 1;
 526         else if (mr->probability < MINSTREL_FRAC(20, 100))
 527                 rate->count = 2;
 528         else if (rtscts)
 529                 rate->count = mr->retry_count_rtscts;
 530         else
 531                 rate->count = mr->retry_count;
 532
 533         rate->flags = IEEE80211_TX_RC_MCS | group->flags;
 534         if (rtscts)
 535                 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
 536         rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
 537 }
 538
 539 static inline int
 540 minstrel_get_duration(int index)
 541 {
 542         const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
 543         return group->duration[index % MCS_GROUP_RATES];
 544 }
 545
 546 static int
 547 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 548 {
 549         struct minstrel_rate_stats *mr;
 550         struct minstrel_mcs_group_data *mg;
 551         int sample_idx = 0;
 552
 553         if (mi->sample_wait > 0) {
 554                 mi->sample_wait--;
 555                 return -1;
 556         }
 557
 558         if (!mi->sample_tries)
 559                 return -1;
 560
 561         mi->sample_tries--;
 562         mg = &mi->groups[mi->sample_group];
 563         sample_idx = sample_table[mg->column][mg->index];
 564         mr = &mg->rates[sample_idx];
 565         sample_idx += mi->sample_group * MCS_GROUP_RATES;
 566         minstrel_next_sample_idx(mi);
 567
 568         /*
 569          * Sampling might add some overhead (RTS, no aggregation)
 570          * to the frame. Hence, don't use sampling for the currently
 571          * used max TP rate.
 572          */
 573         if (sample_idx == mi->max_tp_rate)
 574                 return -1;
 575         /*
 576          * When not using MRR, do not sample if the probability is already
 577          * higher than 95% to avoid wasting airtime
 578          */
 579         if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
 580                 return -1;
 581
 582         /*
 583          * Make sure that lower rates get sampled only occasionally,
 584          * if the link is working perfectly.
 585          */
 586         if (minstrel_get_duration(sample_idx) >
 587             minstrel_get_duration(mi->max_tp_rate)) {
 588                 if (mr->sample_skipped < 20)
 589                         return -1;
 590
 591                 if (mi->sample_slow++ > 2)
 592                         return -1;
 593         }
 594
 595         return sample_idx;
 596 }
 597
 598 static void
 599 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 600                      struct ieee80211_tx_rate_control *txrc)
 601 {
 602         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
 603         struct ieee80211_tx_rate *ar = info->status.rates;
 604         struct minstrel_ht_sta_priv *msp = priv_sta;
 605         struct minstrel_ht_sta *mi = &msp->ht;
 606         struct minstrel_priv *mp = priv;
 607         int sample_idx;
 608         bool sample = false;
 609
 610         if (rate_control_send_low(sta, priv_sta, txrc))
 611                 return;
 612
 613         if (!msp->is_ht)
 614                 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
 615
 616         info->flags |= mi->tx_flags;
 617
 618         /* Don't use EAPOL frames for sampling on non-mrr hw */
 619         if (mp->hw->max_rates == 1 &&
 620             txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
 621                 sample_idx = -1;
 622         else
 623                 sample_idx = minstrel_get_sample_rate(mp, mi);
 624
 625 #ifdef CONFIG_MAC80211_DEBUGFS
 626         /* use fixed index if set */
 627         if (mp->fixed_rate_idx != -1) {
 628                 mi->max_tp_rate = mp->fixed_rate_idx;
 629                 mi->max_tp_rate2 = mp->fixed_rate_idx;
 630                 mi->max_prob_rate = mp->fixed_rate_idx;
 631                 sample_idx = -1;
 632         }
 633 #endif
 634
 635         if (sample_idx >= 0) {
 636                 sample = true;
 637                 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
 638                         true, false);
 639                 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
 640         } else {
 641                 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
 642                         false, false);
 643         }
 644
 645         if (mp->hw->max_rates >= 3) {
 646                 /*
 647                  * At least 3 tx rates supported, use
 648                  * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
 649                  * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
 650                  */
 651                 if (sample_idx >= 0)
 652                         minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
 653                                 false, false);
 654                 else
 655                         minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
 656                                 false, true);
 657
 658                 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
 659                                      false, !sample);
 660
 661                 ar[3].count = 0;
 662                 ar[3].idx = -1;
 663         } else if (mp->hw->max_rates == 2) {
 664                 /*
 665                  * Only 2 tx rates supported, use
 666                  * sample_rate -> max_prob_rate for sampling and
 667                  * max_tp_rate -> max_prob_rate by default.
 668                  */
 669                 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
 670                                      false, !sample);
 671
 672                 ar[2].count = 0;
 673                 ar[2].idx = -1;
 674         } else {
 675                 /* Not using MRR, only use the first rate */
 676                 ar[1].count = 0;
 677                 ar[1].idx = -1;
 678         }
 679
 680         mi->total_packets++;
 681
 682         /* wraparound */
 683         if (mi->total_packets == ~0) {
 684                 mi->total_packets = 0;
 685                 mi->sample_packets = 0;
 686         }
 687 }
 688
 689 static void
 690 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 691                         struct ieee80211_sta *sta, void *priv_sta)
 692 {
 693         struct minstrel_priv *mp = priv;
 694         struct minstrel_ht_sta_priv *msp = priv_sta;
 695         struct minstrel_ht_sta *mi = &msp->ht;
 696         struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
 697         u16 sta_cap = sta->ht_cap.cap;
 698         int n_supported = 0;
 699         int ack_dur;
 700         int stbc;
 701         int i;
 702         unsigned int smps;
 703
 704         /* fall back to the old minstrel for legacy stations */
 705         if (!sta->ht_cap.ht_supported)
 706                 goto use_legacy;
 707
 708         BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
 709                 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
 710
 711         msp->is_ht = true;
 712         memset(mi, 0, sizeof(*mi));
 713         mi->stats_update = jiffies;
 714
 715         ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
 716         mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
 717         mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
 718
 719         mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
 720
 721         /* When using MRR, sample more on the first attempt, without delay */
 722         if (mp->has_mrr) {
 723                 mi->sample_count = 16;
 724                 mi->sample_wait = 0;
 725         } else {
 726                 mi->sample_count = 8;
 727                 mi->sample_wait = 8;
 728         }
 729         mi->sample_tries = 4;
 730
 731         stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
 732                 IEEE80211_HT_CAP_RX_STBC_SHIFT;
 733         mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
 734
 735         if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
 736                 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
 737
 738         smps = (sta_cap & IEEE80211_HT_CAP_SM_PS) >>
 739                 IEEE80211_HT_CAP_SM_PS_SHIFT;
 740
 741         for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
 742                 u16 req = 0;
 743
 744                 mi->groups[i].supported = 0;
 745                 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
 746                         if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
 747                                 req |= IEEE80211_HT_CAP_SGI_40;
 748                         else
 749                                 req |= IEEE80211_HT_CAP_SGI_20;
 750                 }
 751
 752                 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
 753                         req |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
 754
 755                 if ((sta_cap & req) != req)
 756                         continue;
 757
 758                 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
 759                 if (smps == WLAN_HT_CAP_SM_PS_STATIC &&
 760                     minstrel_mcs_groups[i].streams > 1)
 761                         continue;
 762
 763                 mi->groups[i].supported =
 764                         mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
 765
 766                 if (mi->groups[i].supported)
 767                         n_supported++;
 768         }
 769
 770         if (!n_supported)
 771                 goto use_legacy;
 772
 773         return;
 774
 775 use_legacy:
 776         msp->is_ht = false;
 777         memset(&msp->legacy, 0, sizeof(msp->legacy));
 778         msp->legacy.r = msp->ratelist;
 779         msp->legacy.sample_table = msp->sample_table;
 780         return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
 781 }
 782
 783 static void
 784 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
 785                       struct ieee80211_sta *sta, void *priv_sta)
 786 {
 787         minstrel_ht_update_caps(priv, sband, sta, priv_sta);
 788 }
 789
 790 static void
 791 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
 792                         struct ieee80211_sta *sta, void *priv_sta,
 793                         u32 changed)
 794 {
 795         minstrel_ht_update_caps(priv, sband, sta, priv_sta);
 796 }
 797
 798 static void *
 799 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
 800 {
 801         struct ieee80211_supported_band *sband;
 802         struct minstrel_ht_sta_priv *msp;
 803         struct minstrel_priv *mp = priv;
 804         struct ieee80211_hw *hw = mp->hw;
 805         int max_rates = 0;
 806         int i;
 807
 808         for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 809                 sband = hw->wiphy->bands[i];
 810                 if (sband && sband->n_bitrates > max_rates)
 811                         max_rates = sband->n_bitrates;
 812         }
 813
 814         msp = kzalloc(sizeof(*msp), gfp);
 815         if (!msp)
 816                 return NULL;
 817
 818         msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
 819         if (!msp->ratelist)
 820                 goto error;
 821
 822         msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
 823         if (!msp->sample_table)
 824                 goto error1;
 825
 826         return msp;
 827
 828 error1:
 829         kfree(msp->ratelist);
 830 error:
 831         kfree(msp);
 832         return NULL;
 833 }
 834
 835 static void
 836 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
 837 {
 838         struct minstrel_ht_sta_priv *msp = priv_sta;
 839
 840         kfree(msp->sample_table);
 841         kfree(msp->ratelist);
 842         kfree(msp);
 843 }
 844
 845 static void *
 846 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
 847 {
 848         return mac80211_minstrel.alloc(hw, debugfsdir);
 849 }
 850
 851 static void
 852 minstrel_ht_free(void *priv)
 853 {
 854         mac80211_minstrel.free(priv);
 855 }
 856
 857 static struct rate_control_ops mac80211_minstrel_ht = {
 858         .name = "minstrel_ht",
 859         .tx_status = minstrel_ht_tx_status,
 860         .get_rate = minstrel_ht_get_rate,
 861         .rate_init = minstrel_ht_rate_init,
 862         .rate_update = minstrel_ht_rate_update,
 863         .alloc_sta = minstrel_ht_alloc_sta,
 864         .free_sta = minstrel_ht_free_sta,
 865         .alloc = minstrel_ht_alloc,
 866         .free = minstrel_ht_free,
 867 #ifdef CONFIG_MAC80211_DEBUGFS
 868         .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
 869         .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
 870 #endif
 871 };
 872
 873
 874 static void
 875 init_sample_table(void)
 876 {
 877         int col, i, new_idx;
 878         u8 rnd[MCS_GROUP_RATES];
 879
 880         memset(sample_table, 0xff, sizeof(sample_table));
 881         for (col = 0; col < SAMPLE_COLUMNS; col++) {
 882                 for (i = 0; i < MCS_GROUP_RATES; i++) {
 883                         get_random_bytes(rnd, sizeof(rnd));
 884                         new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
 885
 886                         while (sample_table[col][new_idx] != 0xff)
 887                                 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
 888
 889                         sample_table[col][new_idx] = i;
 890                 }
 891         }
 892 }
 893
 894 int __init
 895 rc80211_minstrel_ht_init(void)
 896 {
 897         init_sample_table();
 898         return ieee80211_rate_control_register(&mac80211_minstrel_ht);
 899 }
 900
 901 void
 902 rc80211_minstrel_ht_exit(void)
 903 {
 904         ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
 905 }