1 /* 2 * Copyright (C) 2010-2013 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 #define CCK_DURATION(_bitrate, _short, _len) \ 67 (10 /* SIFS */ + \ 68 (_short ? 72 + 24 : 144 + 48 ) + \ 69 (8 * (_len + 4) * 10) / (_bitrate)) 70 71 #define CCK_ACK_DURATION(_bitrate, _short) \ 72 (CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \ 73 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE)) 74 75 #define CCK_DURATION_LIST(_short) \ 76 CCK_ACK_DURATION(10, _short), \ 77 CCK_ACK_DURATION(20, _short), \ 78 CCK_ACK_DURATION(55, _short), \ 79 CCK_ACK_DURATION(110, _short) 80 81 #define CCK_GROUP \ 82 [MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = { \ 83 .streams = 0, \ 84 .duration = { \ 85 CCK_DURATION_LIST(false), \ 86 CCK_DURATION_LIST(true) \ 87 } \ 88 } 89 90 /* 91 * To enable sufficiently targeted rate sampling, MCS rates are divided into 92 * groups, based on the number of streams and flags (HT40, SGI) that they 93 * use. 94 * 95 * Sortorder has to be fixed for GROUP_IDX macro to be applicable: 96 * HT40 -> SGI -> #streams 97 */ 98 const struct mcs_group minstrel_mcs_groups[] = { 99 MCS_GROUP(1, 0, 0), 100 MCS_GROUP(2, 0, 0), 101 #if MINSTREL_MAX_STREAMS >= 3 102 MCS_GROUP(3, 0, 0), 103 #endif 104 105 MCS_GROUP(1, 1, 0), 106 MCS_GROUP(2, 1, 0), 107 #if MINSTREL_MAX_STREAMS >= 3 108 MCS_GROUP(3, 1, 0), 109 #endif 110 111 MCS_GROUP(1, 0, 1), 112 MCS_GROUP(2, 0, 1), 113 #if MINSTREL_MAX_STREAMS >= 3 114 MCS_GROUP(3, 0, 1), 115 #endif 116 117 MCS_GROUP(1, 1, 1), 118 MCS_GROUP(2, 1, 1), 119 #if MINSTREL_MAX_STREAMS >= 3 120 MCS_GROUP(3, 1, 1), 121 #endif 122 123 /* must be last */ 124 CCK_GROUP 125 }; 126 127 #define MINSTREL_CCK_GROUP (ARRAY_SIZE(minstrel_mcs_groups) - 1) 128 129 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES]; 130 131 /* 132 * Perform EWMA (Exponentially Weighted Moving Average) calculation 133 */ 134 static int 135 minstrel_ewma(int old, int new, int weight) 136 { 137 return (new * (100 - weight) + old * weight) / 100; 138 } 139 140 /* 141 * Look up an MCS group index based on mac80211 rate information 142 */ 143 static int 144 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate) 145 { 146 return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1, 147 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI), 148 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH)); 149 } 150 151 static struct minstrel_rate_stats * 152 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 153 struct ieee80211_tx_rate *rate) 154 { 155 int group, idx; 156 157 if (rate->flags & IEEE80211_TX_RC_MCS) { 158 group = minstrel_ht_get_group_idx(rate); 159 idx = rate->idx % MCS_GROUP_RATES; 160 } else { 161 group = MINSTREL_CCK_GROUP; 162 163 for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) 164 if (rate->idx == mp->cck_rates[idx]) 165 break; 166 167 /* short preamble */ 168 if (!(mi->groups[group].supported & BIT(idx))) 169 idx += 4; 170 } 171 return &mi->groups[group].rates[idx]; 172 } 173 174 static inline struct minstrel_rate_stats * 175 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index) 176 { 177 return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES]; 178 } 179 180 181 /* 182 * Recalculate success probabilities and counters for a rate using EWMA 183 */ 184 static void 185 minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr) 186 { 187 if (unlikely(mr->attempts > 0)) { 188 mr->sample_skipped = 0; 189 mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts); 190 if (!mr->att_hist) 191 mr->probability = mr->cur_prob; 192 else 193 mr->probability = minstrel_ewma(mr->probability, 194 mr->cur_prob, EWMA_LEVEL); 195 mr->att_hist += mr->attempts; 196 mr->succ_hist += mr->success; 197 } else { 198 mr->sample_skipped++; 199 } 200 mr->last_success = mr->success; 201 mr->last_attempts = mr->attempts; 202 mr->success = 0; 203 mr->attempts = 0; 204 } 205 206 /* 207 * Calculate throughput based on the average A-MPDU length, taking into account 208 * the expected number of retransmissions and their expected length 209 */ 210 static void 211 minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate) 212 { 213 struct minstrel_rate_stats *mr; 214 unsigned int usecs = 0; 215 216 mr = &mi->groups[group].rates[rate]; 217 218 if (mr->probability < MINSTREL_FRAC(1, 10)) { 219 mr->cur_tp = 0; 220 return; 221 } 222 223 if (group != MINSTREL_CCK_GROUP) 224 usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len); 225 226 usecs += minstrel_mcs_groups[group].duration[rate]; 227 mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability); 228 } 229 230 /* 231 * Update rate statistics and select new primary rates 232 * 233 * Rules for rate selection: 234 * - max_prob_rate must use only one stream, as a tradeoff between delivery 235 * probability and throughput during strong fluctuations 236 * - as long as the max prob rate has a probability of more than 3/4, pick 237 * higher throughput rates, even if the probablity is a bit lower 238 */ 239 static void 240 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) 241 { 242 struct minstrel_mcs_group_data *mg; 243 struct minstrel_rate_stats *mr; 244 int cur_prob, cur_prob_tp, cur_tp, cur_tp2; 245 int group, i, index; 246 247 if (mi->ampdu_packets > 0) { 248 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len, 249 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL); 250 mi->ampdu_len = 0; 251 mi->ampdu_packets = 0; 252 } 253 254 mi->sample_slow = 0; 255 mi->sample_count = 0; 256 mi->max_tp_rate = 0; 257 mi->max_tp_rate2 = 0; 258 mi->max_prob_rate = 0; 259 260 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) { 261 cur_prob = 0; 262 cur_prob_tp = 0; 263 cur_tp = 0; 264 cur_tp2 = 0; 265 266 mg = &mi->groups[group]; 267 if (!mg->supported) 268 continue; 269 270 mg->max_tp_rate = 0; 271 mg->max_tp_rate2 = 0; 272 mg->max_prob_rate = 0; 273 mi->sample_count++; 274 275 for (i = 0; i < MCS_GROUP_RATES; i++) { 276 if (!(mg->supported & BIT(i))) 277 continue; 278 279 mr = &mg->rates[i]; 280 mr->retry_updated = false; 281 index = MCS_GROUP_RATES * group + i; 282 minstrel_calc_rate_ewma(mr); 283 minstrel_ht_calc_tp(mi, group, i); 284 285 if (!mr->cur_tp) 286 continue; 287 288 if ((mr->cur_tp > cur_prob_tp && mr->probability > 289 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) { 290 mg->max_prob_rate = index; 291 cur_prob = mr->probability; 292 cur_prob_tp = mr->cur_tp; 293 } 294 295 if (mr->cur_tp > cur_tp) { 296 swap(index, mg->max_tp_rate); 297 cur_tp = mr->cur_tp; 298 mr = minstrel_get_ratestats(mi, index); 299 } 300 301 if (index >= mg->max_tp_rate) 302 continue; 303 304 if (mr->cur_tp > cur_tp2) { 305 mg->max_tp_rate2 = index; 306 cur_tp2 = mr->cur_tp; 307 } 308 } 309 } 310 311 /* try to sample up to half of the available rates during each interval */ 312 mi->sample_count *= 4; 313 314 cur_prob = 0; 315 cur_prob_tp = 0; 316 cur_tp = 0; 317 cur_tp2 = 0; 318 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) { 319 mg = &mi->groups[group]; 320 if (!mg->supported) 321 continue; 322 323 mr = minstrel_get_ratestats(mi, mg->max_prob_rate); 324 if (cur_prob_tp < mr->cur_tp && 325 minstrel_mcs_groups[group].streams == 1) { 326 mi->max_prob_rate = mg->max_prob_rate; 327 cur_prob = mr->cur_prob; 328 cur_prob_tp = mr->cur_tp; 329 } 330 331 mr = minstrel_get_ratestats(mi, mg->max_tp_rate); 332 if (cur_tp < mr->cur_tp) { 333 mi->max_tp_rate2 = mi->max_tp_rate; 334 cur_tp2 = cur_tp; 335 mi->max_tp_rate = mg->max_tp_rate; 336 cur_tp = mr->cur_tp; 337 } 338 339 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2); 340 if (cur_tp2 < mr->cur_tp) { 341 mi->max_tp_rate2 = mg->max_tp_rate2; 342 cur_tp2 = mr->cur_tp; 343 } 344 } 345 346 mi->stats_update = jiffies; 347 } 348 349 static bool 350 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate) 351 { 352 if (rate->idx < 0) 353 return false; 354 355 if (!rate->count) 356 return false; 357 358 if (rate->flags & IEEE80211_TX_RC_MCS) 359 return true; 360 361 return rate->idx == mp->cck_rates[0] || 362 rate->idx == mp->cck_rates[1] || 363 rate->idx == mp->cck_rates[2] || 364 rate->idx == mp->cck_rates[3]; 365 } 366 367 static void 368 minstrel_next_sample_idx(struct minstrel_ht_sta *mi) 369 { 370 struct minstrel_mcs_group_data *mg; 371 372 for (;;) { 373 mi->sample_group++; 374 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups); 375 mg = &mi->groups[mi->sample_group]; 376 377 if (!mg->supported) 378 continue; 379 380 if (++mg->index >= MCS_GROUP_RATES) { 381 mg->index = 0; 382 if (++mg->column >= ARRAY_SIZE(sample_table)) 383 mg->column = 0; 384 } 385 break; 386 } 387 } 388 389 static void 390 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx, 391 bool primary) 392 { 393 int group, orig_group; 394 395 orig_group = group = *idx / MCS_GROUP_RATES; 396 while (group > 0) { 397 group--; 398 399 if (!mi->groups[group].supported) 400 continue; 401 402 if (minstrel_mcs_groups[group].streams > 403 minstrel_mcs_groups[orig_group].streams) 404 continue; 405 406 if (primary) 407 *idx = mi->groups[group].max_tp_rate; 408 else 409 *idx = mi->groups[group].max_tp_rate2; 410 break; 411 } 412 } 413 414 static void 415 minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb) 416 { 417 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 418 struct sta_info *sta = container_of(pubsta, struct sta_info, sta); 419 u16 tid; 420 421 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control))) 422 return; 423 424 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE))) 425 return; 426 427 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK; 428 if (likely(sta->ampdu_mlme.tid_tx[tid])) 429 return; 430 431 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO) 432 return; 433 434 ieee80211_start_tx_ba_session(pubsta, tid, 5000); 435 } 436 437 static void 438 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband, 439 struct ieee80211_sta *sta, void *priv_sta, 440 struct sk_buff *skb) 441 { 442 struct minstrel_ht_sta_priv *msp = priv_sta; 443 struct minstrel_ht_sta *mi = &msp->ht; 444 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 445 struct ieee80211_tx_rate *ar = info->status.rates; 446 struct minstrel_rate_stats *rate, *rate2; 447 struct minstrel_priv *mp = priv; 448 bool last; 449 int i; 450 451 if (!msp->is_ht) 452 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb); 453 454 /* This packet was aggregated but doesn't carry status info */ 455 if ((info->flags & IEEE80211_TX_CTL_AMPDU) && 456 !(info->flags & IEEE80211_TX_STAT_AMPDU)) 457 return; 458 459 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) { 460 info->status.ampdu_ack_len = 461 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0); 462 info->status.ampdu_len = 1; 463 } 464 465 mi->ampdu_packets++; 466 mi->ampdu_len += info->status.ampdu_len; 467 468 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) { 469 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len); 470 mi->sample_tries = 2; 471 mi->sample_count--; 472 } 473 474 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) 475 mi->sample_packets += info->status.ampdu_len; 476 477 last = !minstrel_ht_txstat_valid(mp, &ar[0]); 478 for (i = 0; !last; i++) { 479 last = (i == IEEE80211_TX_MAX_RATES - 1) || 480 !minstrel_ht_txstat_valid(mp, &ar[i + 1]); 481 482 rate = minstrel_ht_get_stats(mp, mi, &ar[i]); 483 484 if (last) 485 rate->success += info->status.ampdu_ack_len; 486 487 rate->attempts += ar[i].count * info->status.ampdu_len; 488 } 489 490 /* 491 * check for sudden death of spatial multiplexing, 492 * downgrade to a lower number of streams if necessary. 493 */ 494 rate = minstrel_get_ratestats(mi, mi->max_tp_rate); 495 if (rate->attempts > 30 && 496 MINSTREL_FRAC(rate->success, rate->attempts) < 497 MINSTREL_FRAC(20, 100)) 498 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true); 499 500 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2); 501 if (rate2->attempts > 30 && 502 MINSTREL_FRAC(rate2->success, rate2->attempts) < 503 MINSTREL_FRAC(20, 100)) 504 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false); 505 506 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) { 507 minstrel_ht_update_stats(mp, mi); 508 if (!(info->flags & IEEE80211_TX_CTL_AMPDU) && 509 mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) 510 minstrel_aggr_check(sta, skb); 511 } 512 } 513 514 static void 515 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 516 int index) 517 { 518 struct minstrel_rate_stats *mr; 519 const struct mcs_group *group; 520 unsigned int tx_time, tx_time_rtscts, tx_time_data; 521 unsigned int cw = mp->cw_min; 522 unsigned int ctime = 0; 523 unsigned int t_slot = 9; /* FIXME */ 524 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len); 525 unsigned int overhead = 0, overhead_rtscts = 0; 526 527 mr = minstrel_get_ratestats(mi, index); 528 if (mr->probability < MINSTREL_FRAC(1, 10)) { 529 mr->retry_count = 1; 530 mr->retry_count_rtscts = 1; 531 return; 532 } 533 534 mr->retry_count = 2; 535 mr->retry_count_rtscts = 2; 536 mr->retry_updated = true; 537 538 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES]; 539 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len; 540 541 /* Contention time for first 2 tries */ 542 ctime = (t_slot * cw) >> 1; 543 cw = min((cw << 1) | 1, mp->cw_max); 544 ctime += (t_slot * cw) >> 1; 545 cw = min((cw << 1) | 1, mp->cw_max); 546 547 if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) { 548 overhead = mi->overhead; 549 overhead_rtscts = mi->overhead_rtscts; 550 } 551 552 /* Total TX time for data and Contention after first 2 tries */ 553 tx_time = ctime + 2 * (overhead + tx_time_data); 554 tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data); 555 556 /* See how many more tries we can fit inside segment size */ 557 do { 558 /* Contention time for this try */ 559 ctime = (t_slot * cw) >> 1; 560 cw = min((cw << 1) | 1, mp->cw_max); 561 562 /* Total TX time after this try */ 563 tx_time += ctime + overhead + tx_time_data; 564 tx_time_rtscts += ctime + overhead_rtscts + tx_time_data; 565 566 if (tx_time_rtscts < mp->segment_size) 567 mr->retry_count_rtscts++; 568 } while ((tx_time < mp->segment_size) && 569 (++mr->retry_count < mp->max_retry)); 570 } 571 572 573 static void 574 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 575 struct ieee80211_tx_rate *rate, int index, 576 bool sample, bool rtscts) 577 { 578 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES]; 579 struct minstrel_rate_stats *mr; 580 581 mr = minstrel_get_ratestats(mi, index); 582 if (!mr->retry_updated) 583 minstrel_calc_retransmit(mp, mi, index); 584 585 if (sample) 586 rate->count = 1; 587 else if (mr->probability < MINSTREL_FRAC(20, 100)) 588 rate->count = 2; 589 else if (rtscts) 590 rate->count = mr->retry_count_rtscts; 591 else 592 rate->count = mr->retry_count; 593 594 rate->flags = 0; 595 if (rtscts) 596 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS; 597 598 if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) { 599 rate->idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)]; 600 return; 601 } 602 603 rate->flags |= IEEE80211_TX_RC_MCS | group->flags; 604 rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES; 605 } 606 607 static inline int 608 minstrel_get_duration(int index) 609 { 610 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES]; 611 return group->duration[index % MCS_GROUP_RATES]; 612 } 613 614 static int 615 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) 616 { 617 struct minstrel_rate_stats *mr; 618 struct minstrel_mcs_group_data *mg; 619 int sample_idx = 0; 620 621 if (mi->sample_wait > 0) { 622 mi->sample_wait--; 623 return -1; 624 } 625 626 if (!mi->sample_tries) 627 return -1; 628 629 mi->sample_tries--; 630 mg = &mi->groups[mi->sample_group]; 631 sample_idx = sample_table[mg->column][mg->index]; 632 mr = &mg->rates[sample_idx]; 633 sample_idx += mi->sample_group * MCS_GROUP_RATES; 634 minstrel_next_sample_idx(mi); 635 636 /* 637 * Sampling might add some overhead (RTS, no aggregation) 638 * to the frame. Hence, don't use sampling for the currently 639 * used max TP rate. 640 */ 641 if (sample_idx == mi->max_tp_rate) 642 return -1; 643 /* 644 * When not using MRR, do not sample if the probability is already 645 * higher than 95% to avoid wasting airtime 646 */ 647 if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100))) 648 return -1; 649 650 /* 651 * Make sure that lower rates get sampled only occasionally, 652 * if the link is working perfectly. 653 */ 654 if (minstrel_get_duration(sample_idx) > 655 minstrel_get_duration(mi->max_tp_rate)) { 656 if (mr->sample_skipped < 20) 657 return -1; 658 659 if (mi->sample_slow++ > 2) 660 return -1; 661 } 662 663 return sample_idx; 664 } 665 666 static void 667 minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp, 668 struct minstrel_ht_sta *mi, bool val) 669 { 670 u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported; 671 672 if (!supported || !mi->cck_supported_short) 673 return; 674 675 if (supported & (mi->cck_supported_short << (val * 4))) 676 return; 677 678 supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4); 679 mi->groups[MINSTREL_CCK_GROUP].supported = supported; 680 } 681 682 static void 683 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta, 684 struct ieee80211_tx_rate_control *txrc) 685 { 686 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb); 687 struct ieee80211_tx_rate *ar = info->status.rates; 688 struct minstrel_ht_sta_priv *msp = priv_sta; 689 struct minstrel_ht_sta *mi = &msp->ht; 690 struct minstrel_priv *mp = priv; 691 int sample_idx; 692 bool sample = false; 693 694 if (rate_control_send_low(sta, priv_sta, txrc)) 695 return; 696 697 if (!msp->is_ht) 698 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc); 699 700 info->flags |= mi->tx_flags; 701 minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble); 702 703 /* Don't use EAPOL frames for sampling on non-mrr hw */ 704 if (mp->hw->max_rates == 1 && 705 txrc->skb->protocol == cpu_to_be16(ETH_P_PAE)) 706 sample_idx = -1; 707 else 708 sample_idx = minstrel_get_sample_rate(mp, mi); 709 710 #ifdef CONFIG_MAC80211_DEBUGFS 711 /* use fixed index if set */ 712 if (mp->fixed_rate_idx != -1) { 713 mi->max_tp_rate = mp->fixed_rate_idx; 714 mi->max_tp_rate2 = mp->fixed_rate_idx; 715 mi->max_prob_rate = mp->fixed_rate_idx; 716 sample_idx = -1; 717 } 718 #endif 719 720 if (sample_idx >= 0) { 721 sample = true; 722 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx, 723 true, false); 724 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE; 725 } else { 726 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate, 727 false, false); 728 } 729 730 if (mp->hw->max_rates >= 3) { 731 /* 732 * At least 3 tx rates supported, use 733 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and 734 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default. 735 */ 736 if (sample_idx >= 0) 737 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate, 738 false, false); 739 else 740 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2, 741 false, true); 742 743 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate, 744 false, !sample); 745 746 ar[3].count = 0; 747 ar[3].idx = -1; 748 } else if (mp->hw->max_rates == 2) { 749 /* 750 * Only 2 tx rates supported, use 751 * sample_rate -> max_prob_rate for sampling and 752 * max_tp_rate -> max_prob_rate by default. 753 */ 754 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate, 755 false, !sample); 756 757 ar[2].count = 0; 758 ar[2].idx = -1; 759 } else { 760 /* Not using MRR, only use the first rate */ 761 ar[1].count = 0; 762 ar[1].idx = -1; 763 } 764 765 mi->total_packets++; 766 767 /* wraparound */ 768 if (mi->total_packets == ~0) { 769 mi->total_packets = 0; 770 mi->sample_packets = 0; 771 } 772 } 773 774 static void 775 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 776 struct ieee80211_supported_band *sband, 777 struct ieee80211_sta *sta) 778 { 779 int i; 780 781 if (sband->band != IEEE80211_BAND_2GHZ) 782 return; 783 784 mi->cck_supported = 0; 785 mi->cck_supported_short = 0; 786 for (i = 0; i < 4; i++) { 787 if (!rate_supported(sta, sband->band, mp->cck_rates[i])) 788 continue; 789 790 mi->cck_supported |= BIT(i); 791 if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE) 792 mi->cck_supported_short |= BIT(i); 793 } 794 795 mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported; 796 } 797 798 static void 799 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband, 800 struct ieee80211_sta *sta, void *priv_sta) 801 { 802 struct minstrel_priv *mp = priv; 803 struct minstrel_ht_sta_priv *msp = priv_sta; 804 struct minstrel_ht_sta *mi = &msp->ht; 805 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs; 806 u16 sta_cap = sta->ht_cap.cap; 807 int n_supported = 0; 808 int ack_dur; 809 int stbc; 810 int i; 811 812 /* fall back to the old minstrel for legacy stations */ 813 if (!sta->ht_cap.ht_supported) 814 goto use_legacy; 815 816 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != 817 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1); 818 819 msp->is_ht = true; 820 memset(mi, 0, sizeof(*mi)); 821 mi->stats_update = jiffies; 822 823 ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1); 824 mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur; 825 mi->overhead_rtscts = mi->overhead + 2 * ack_dur; 826 827 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1); 828 829 /* When using MRR, sample more on the first attempt, without delay */ 830 if (mp->has_mrr) { 831 mi->sample_count = 16; 832 mi->sample_wait = 0; 833 } else { 834 mi->sample_count = 8; 835 mi->sample_wait = 8; 836 } 837 mi->sample_tries = 4; 838 839 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >> 840 IEEE80211_HT_CAP_RX_STBC_SHIFT; 841 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT; 842 843 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING) 844 mi->tx_flags |= IEEE80211_TX_CTL_LDPC; 845 846 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) { 847 mi->groups[i].supported = 0; 848 if (i == MINSTREL_CCK_GROUP) { 849 minstrel_ht_update_cck(mp, mi, sband, sta); 850 continue; 851 } 852 853 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) { 854 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) { 855 if (!(sta_cap & IEEE80211_HT_CAP_SGI_40)) 856 continue; 857 } else { 858 if (!(sta_cap & IEEE80211_HT_CAP_SGI_20)) 859 continue; 860 } 861 } 862 863 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH && 864 sta->bandwidth < IEEE80211_STA_RX_BW_40) 865 continue; 866 867 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */ 868 if (sta->smps_mode == IEEE80211_SMPS_STATIC && 869 minstrel_mcs_groups[i].streams > 1) 870 continue; 871 872 mi->groups[i].supported = 873 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1]; 874 875 if (mi->groups[i].supported) 876 n_supported++; 877 } 878 879 if (!n_supported) 880 goto use_legacy; 881 882 return; 883 884 use_legacy: 885 msp->is_ht = false; 886 memset(&msp->legacy, 0, sizeof(msp->legacy)); 887 msp->legacy.r = msp->ratelist; 888 msp->legacy.sample_table = msp->sample_table; 889 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy); 890 } 891 892 static void 893 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband, 894 struct ieee80211_sta *sta, void *priv_sta) 895 { 896 minstrel_ht_update_caps(priv, sband, sta, priv_sta); 897 } 898 899 static void 900 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband, 901 struct ieee80211_sta *sta, void *priv_sta, 902 u32 changed) 903 { 904 minstrel_ht_update_caps(priv, sband, sta, priv_sta); 905 } 906 907 static void * 908 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp) 909 { 910 struct ieee80211_supported_band *sband; 911 struct minstrel_ht_sta_priv *msp; 912 struct minstrel_priv *mp = priv; 913 struct ieee80211_hw *hw = mp->hw; 914 int max_rates = 0; 915 int i; 916 917 for (i = 0; i < IEEE80211_NUM_BANDS; i++) { 918 sband = hw->wiphy->bands[i]; 919 if (sband && sband->n_bitrates > max_rates) 920 max_rates = sband->n_bitrates; 921 } 922 923 msp = kzalloc(sizeof(*msp), gfp); 924 if (!msp) 925 return NULL; 926 927 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp); 928 if (!msp->ratelist) 929 goto error; 930 931 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp); 932 if (!msp->sample_table) 933 goto error1; 934 935 return msp; 936 937 error1: 938 kfree(msp->ratelist); 939 error: 940 kfree(msp); 941 return NULL; 942 } 943 944 static void 945 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta) 946 { 947 struct minstrel_ht_sta_priv *msp = priv_sta; 948 949 kfree(msp->sample_table); 950 kfree(msp->ratelist); 951 kfree(msp); 952 } 953 954 static void * 955 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir) 956 { 957 return mac80211_minstrel.alloc(hw, debugfsdir); 958 } 959 960 static void 961 minstrel_ht_free(void *priv) 962 { 963 mac80211_minstrel.free(priv); 964 } 965 966 static struct rate_control_ops mac80211_minstrel_ht = { 967 .name = "minstrel_ht", 968 .tx_status = minstrel_ht_tx_status, 969 .get_rate = minstrel_ht_get_rate, 970 .rate_init = minstrel_ht_rate_init, 971 .rate_update = minstrel_ht_rate_update, 972 .alloc_sta = minstrel_ht_alloc_sta, 973 .free_sta = minstrel_ht_free_sta, 974 .alloc = minstrel_ht_alloc, 975 .free = minstrel_ht_free, 976 #ifdef CONFIG_MAC80211_DEBUGFS 977 .add_sta_debugfs = minstrel_ht_add_sta_debugfs, 978 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs, 979 #endif 980 }; 981 982 983 static void 984 init_sample_table(void) 985 { 986 int col, i, new_idx; 987 u8 rnd[MCS_GROUP_RATES]; 988 989 memset(sample_table, 0xff, sizeof(sample_table)); 990 for (col = 0; col < SAMPLE_COLUMNS; col++) { 991 for (i = 0; i < MCS_GROUP_RATES; i++) { 992 get_random_bytes(rnd, sizeof(rnd)); 993 new_idx = (i + rnd[i]) % MCS_GROUP_RATES; 994 995 while (sample_table[col][new_idx] != 0xff) 996 new_idx = (new_idx + 1) % MCS_GROUP_RATES; 997 998 sample_table[col][new_idx] = i; 999 } 1000 } 1001 } 1002 1003 int __init 1004 rc80211_minstrel_ht_init(void) 1005 { 1006 init_sample_table(); 1007 return ieee80211_rate_control_register(&mac80211_minstrel_ht); 1008 } 1009 1010 void 1011 rc80211_minstrel_ht_exit(void) 1012 { 1013 ieee80211_rate_control_unregister(&mac80211_minstrel_ht); 1014 } 1015