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 21 /* Number of bits for an average sized packet */ 22 #define MCS_NBITS (AVG_PKT_SIZE << 3) 23 24 /* Number of symbols for a packet with (bps) bits per symbol */ 25 #define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps)) 26 27 /* Transmission time (nanoseconds) for a packet containing (syms) symbols */ 28 #define MCS_SYMBOL_TIME(sgi, syms) \ 29 (sgi ? \ 30 ((syms) * 18000 + 4000) / 5 : /* syms * 3.6 us */ \ 31 ((syms) * 1000) << 2 /* syms * 4 us */ \ 32 ) 33 34 /* Transmit duration for the raw data part of an average sized packet */ 35 #define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps))) 36 37 /* 38 * Define group sort order: HT40 -> SGI -> #streams 39 */ 40 #define GROUP_IDX(_streams, _sgi, _ht40) \ 41 MINSTREL_MAX_STREAMS * 2 * _ht40 + \ 42 MINSTREL_MAX_STREAMS * _sgi + \ 43 _streams - 1 44 45 /* MCS rate information for an MCS group */ 46 #define MCS_GROUP(_streams, _sgi, _ht40) \ 47 [GROUP_IDX(_streams, _sgi, _ht40)] = { \ 48 .streams = _streams, \ 49 .flags = \ 50 (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \ 51 (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \ 52 .duration = { \ 53 MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \ 54 MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \ 55 MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \ 56 MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \ 57 MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \ 58 MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \ 59 MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \ 60 MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \ 61 } \ 62 } 63 64 #define CCK_DURATION(_bitrate, _short, _len) \ 65 (1000 * (10 /* SIFS */ + \ 66 (_short ? 72 + 24 : 144 + 48) + \ 67 (8 * (_len + 4) * 10) / (_bitrate))) 68 69 #define CCK_ACK_DURATION(_bitrate, _short) \ 70 (CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \ 71 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE)) 72 73 #define CCK_DURATION_LIST(_short) \ 74 CCK_ACK_DURATION(10, _short), \ 75 CCK_ACK_DURATION(20, _short), \ 76 CCK_ACK_DURATION(55, _short), \ 77 CCK_ACK_DURATION(110, _short) 78 79 #define CCK_GROUP \ 80 [MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = { \ 81 .streams = 0, \ 82 .duration = { \ 83 CCK_DURATION_LIST(false), \ 84 CCK_DURATION_LIST(true) \ 85 } \ 86 } 87 88 /* 89 * To enable sufficiently targeted rate sampling, MCS rates are divided into 90 * groups, based on the number of streams and flags (HT40, SGI) that they 91 * use. 92 * 93 * Sortorder has to be fixed for GROUP_IDX macro to be applicable: 94 * HT40 -> SGI -> #streams 95 */ 96 const struct mcs_group minstrel_mcs_groups[] = { 97 MCS_GROUP(1, 0, 0), 98 MCS_GROUP(2, 0, 0), 99 #if MINSTREL_MAX_STREAMS >= 3 100 MCS_GROUP(3, 0, 0), 101 #endif 102 103 MCS_GROUP(1, 1, 0), 104 MCS_GROUP(2, 1, 0), 105 #if MINSTREL_MAX_STREAMS >= 3 106 MCS_GROUP(3, 1, 0), 107 #endif 108 109 MCS_GROUP(1, 0, 1), 110 MCS_GROUP(2, 0, 1), 111 #if MINSTREL_MAX_STREAMS >= 3 112 MCS_GROUP(3, 0, 1), 113 #endif 114 115 MCS_GROUP(1, 1, 1), 116 MCS_GROUP(2, 1, 1), 117 #if MINSTREL_MAX_STREAMS >= 3 118 MCS_GROUP(3, 1, 1), 119 #endif 120 121 /* must be last */ 122 CCK_GROUP 123 }; 124 125 #define MINSTREL_CCK_GROUP (ARRAY_SIZE(minstrel_mcs_groups) - 1) 126 127 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly; 128 129 static void 130 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi); 131 132 /* 133 * Look up an MCS group index based on mac80211 rate information 134 */ 135 static int 136 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate) 137 { 138 return GROUP_IDX((rate->idx / 8) + 1, 139 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI), 140 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH)); 141 } 142 143 static struct minstrel_rate_stats * 144 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 145 struct ieee80211_tx_rate *rate) 146 { 147 int group, idx; 148 149 if (rate->flags & IEEE80211_TX_RC_MCS) { 150 group = minstrel_ht_get_group_idx(rate); 151 idx = rate->idx % 8; 152 } else { 153 group = MINSTREL_CCK_GROUP; 154 155 for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) 156 if (rate->idx == mp->cck_rates[idx]) 157 break; 158 159 /* short preamble */ 160 if (!(mi->groups[group].supported & BIT(idx))) 161 idx += 4; 162 } 163 return &mi->groups[group].rates[idx]; 164 } 165 166 static inline struct minstrel_rate_stats * 167 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index) 168 { 169 return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES]; 170 } 171 172 173 /* 174 * Recalculate success probabilities and counters for a rate using EWMA 175 */ 176 static void 177 minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr) 178 { 179 if (unlikely(mr->attempts > 0)) { 180 mr->sample_skipped = 0; 181 mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts); 182 if (!mr->att_hist) 183 mr->probability = mr->cur_prob; 184 else 185 mr->probability = minstrel_ewma(mr->probability, 186 mr->cur_prob, EWMA_LEVEL); 187 mr->att_hist += mr->attempts; 188 mr->succ_hist += mr->success; 189 } else { 190 mr->sample_skipped++; 191 } 192 mr->last_success = mr->success; 193 mr->last_attempts = mr->attempts; 194 mr->success = 0; 195 mr->attempts = 0; 196 } 197 198 /* 199 * Calculate throughput based on the average A-MPDU length, taking into account 200 * the expected number of retransmissions and their expected length 201 */ 202 static void 203 minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate) 204 { 205 struct minstrel_rate_stats *mr; 206 unsigned int nsecs = 0; 207 unsigned int tp; 208 unsigned int prob; 209 210 mr = &mi->groups[group].rates[rate]; 211 prob = mr->probability; 212 213 if (prob < MINSTREL_FRAC(1, 10)) { 214 mr->cur_tp = 0; 215 return; 216 } 217 218 /* 219 * For the throughput calculation, limit the probability value to 90% to 220 * account for collision related packet error rate fluctuation 221 */ 222 if (prob > MINSTREL_FRAC(9, 10)) 223 prob = MINSTREL_FRAC(9, 10); 224 225 if (group != MINSTREL_CCK_GROUP) 226 nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len); 227 228 nsecs += minstrel_mcs_groups[group].duration[rate]; 229 tp = 1000000 * ((prob * 1000) / nsecs); 230 231 mr->cur_tp = MINSTREL_TRUNC(tp); 232 } 233 234 /* 235 * Update rate statistics and select new primary rates 236 * 237 * Rules for rate selection: 238 * - max_prob_rate must use only one stream, as a tradeoff between delivery 239 * probability and throughput during strong fluctuations 240 * - as long as the max prob rate has a probability of more than 3/4, pick 241 * higher throughput rates, even if the probablity is a bit lower 242 */ 243 static void 244 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) 245 { 246 struct minstrel_mcs_group_data *mg; 247 struct minstrel_rate_stats *mr; 248 int cur_prob, cur_prob_tp, cur_tp, cur_tp2; 249 int group, i, index; 250 bool mi_rates_valid = false; 251 252 if (mi->ampdu_packets > 0) { 253 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len, 254 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL); 255 mi->ampdu_len = 0; 256 mi->ampdu_packets = 0; 257 } 258 259 mi->sample_slow = 0; 260 mi->sample_count = 0; 261 262 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) { 263 bool mg_rates_valid = false; 264 265 cur_prob = 0; 266 cur_prob_tp = 0; 267 cur_tp = 0; 268 cur_tp2 = 0; 269 270 mg = &mi->groups[group]; 271 if (!mg->supported) 272 continue; 273 274 mi->sample_count++; 275 276 for (i = 0; i < MCS_GROUP_RATES; i++) { 277 if (!(mg->supported & BIT(i))) 278 continue; 279 280 index = MCS_GROUP_RATES * group + i; 281 282 /* initialize rates selections starting indexes */ 283 if (!mg_rates_valid) { 284 mg->max_tp_rate = mg->max_tp_rate2 = 285 mg->max_prob_rate = i; 286 if (!mi_rates_valid) { 287 mi->max_tp_rate = mi->max_tp_rate2 = 288 mi->max_prob_rate = index; 289 mi_rates_valid = true; 290 } 291 mg_rates_valid = true; 292 } 293 294 mr = &mg->rates[i]; 295 mr->retry_updated = false; 296 minstrel_calc_rate_ewma(mr); 297 minstrel_ht_calc_tp(mi, group, i); 298 299 if (!mr->cur_tp) 300 continue; 301 302 if ((mr->cur_tp > cur_prob_tp && mr->probability > 303 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) { 304 mg->max_prob_rate = index; 305 cur_prob = mr->probability; 306 cur_prob_tp = mr->cur_tp; 307 } 308 309 if (mr->cur_tp > cur_tp) { 310 swap(index, mg->max_tp_rate); 311 cur_tp = mr->cur_tp; 312 mr = minstrel_get_ratestats(mi, index); 313 } 314 315 if (index >= mg->max_tp_rate) 316 continue; 317 318 if (mr->cur_tp > cur_tp2) { 319 mg->max_tp_rate2 = index; 320 cur_tp2 = mr->cur_tp; 321 } 322 } 323 } 324 325 /* try to sample all available rates during each interval */ 326 mi->sample_count *= 8; 327 328 cur_prob = 0; 329 cur_prob_tp = 0; 330 cur_tp = 0; 331 cur_tp2 = 0; 332 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) { 333 mg = &mi->groups[group]; 334 if (!mg->supported) 335 continue; 336 337 mr = minstrel_get_ratestats(mi, mg->max_tp_rate); 338 if (cur_tp < mr->cur_tp) { 339 mi->max_tp_rate2 = mi->max_tp_rate; 340 cur_tp2 = cur_tp; 341 mi->max_tp_rate = mg->max_tp_rate; 342 cur_tp = mr->cur_tp; 343 mi->max_prob_streams = minstrel_mcs_groups[group].streams - 1; 344 } 345 346 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2); 347 if (cur_tp2 < mr->cur_tp) { 348 mi->max_tp_rate2 = mg->max_tp_rate2; 349 cur_tp2 = mr->cur_tp; 350 } 351 } 352 353 if (mi->max_prob_streams < 1) 354 mi->max_prob_streams = 1; 355 356 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) { 357 mg = &mi->groups[group]; 358 if (!mg->supported) 359 continue; 360 mr = minstrel_get_ratestats(mi, mg->max_prob_rate); 361 if (cur_prob_tp < mr->cur_tp && 362 minstrel_mcs_groups[group].streams <= mi->max_prob_streams) { 363 mi->max_prob_rate = mg->max_prob_rate; 364 cur_prob = mr->cur_prob; 365 cur_prob_tp = mr->cur_tp; 366 } 367 } 368 369 #ifdef CONFIG_MAC80211_DEBUGFS 370 /* use fixed index if set */ 371 if (mp->fixed_rate_idx != -1) { 372 mi->max_tp_rate = mp->fixed_rate_idx; 373 mi->max_tp_rate2 = mp->fixed_rate_idx; 374 mi->max_prob_rate = mp->fixed_rate_idx; 375 } 376 #endif 377 378 mi->stats_update = jiffies; 379 } 380 381 static bool 382 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate) 383 { 384 if (rate->idx < 0) 385 return false; 386 387 if (!rate->count) 388 return false; 389 390 if (rate->flags & IEEE80211_TX_RC_MCS) 391 return true; 392 393 return rate->idx == mp->cck_rates[0] || 394 rate->idx == mp->cck_rates[1] || 395 rate->idx == mp->cck_rates[2] || 396 rate->idx == mp->cck_rates[3]; 397 } 398 399 static void 400 minstrel_next_sample_idx(struct minstrel_ht_sta *mi) 401 { 402 struct minstrel_mcs_group_data *mg; 403 404 for (;;) { 405 mi->sample_group++; 406 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups); 407 mg = &mi->groups[mi->sample_group]; 408 409 if (!mg->supported) 410 continue; 411 412 if (++mg->index >= MCS_GROUP_RATES) { 413 mg->index = 0; 414 if (++mg->column >= ARRAY_SIZE(sample_table)) 415 mg->column = 0; 416 } 417 break; 418 } 419 } 420 421 static void 422 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx, 423 bool primary) 424 { 425 int group, orig_group; 426 427 orig_group = group = *idx / MCS_GROUP_RATES; 428 while (group > 0) { 429 group--; 430 431 if (!mi->groups[group].supported) 432 continue; 433 434 if (minstrel_mcs_groups[group].streams > 435 minstrel_mcs_groups[orig_group].streams) 436 continue; 437 438 if (primary) 439 *idx = mi->groups[group].max_tp_rate; 440 else 441 *idx = mi->groups[group].max_tp_rate2; 442 break; 443 } 444 } 445 446 static void 447 minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb) 448 { 449 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; 450 struct sta_info *sta = container_of(pubsta, struct sta_info, sta); 451 u16 tid; 452 453 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control))) 454 return; 455 456 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE))) 457 return; 458 459 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK; 460 if (likely(sta->ampdu_mlme.tid_tx[tid])) 461 return; 462 463 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO) 464 return; 465 466 ieee80211_start_tx_ba_session(pubsta, tid, 5000); 467 } 468 469 static void 470 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband, 471 struct ieee80211_sta *sta, void *priv_sta, 472 struct sk_buff *skb) 473 { 474 struct minstrel_ht_sta_priv *msp = priv_sta; 475 struct minstrel_ht_sta *mi = &msp->ht; 476 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); 477 struct ieee80211_tx_rate *ar = info->status.rates; 478 struct minstrel_rate_stats *rate, *rate2; 479 struct minstrel_priv *mp = priv; 480 bool last, update = false; 481 int i; 482 483 if (!msp->is_ht) 484 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb); 485 486 /* This packet was aggregated but doesn't carry status info */ 487 if ((info->flags & IEEE80211_TX_CTL_AMPDU) && 488 !(info->flags & IEEE80211_TX_STAT_AMPDU)) 489 return; 490 491 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) { 492 info->status.ampdu_ack_len = 493 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0); 494 info->status.ampdu_len = 1; 495 } 496 497 mi->ampdu_packets++; 498 mi->ampdu_len += info->status.ampdu_len; 499 500 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) { 501 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len); 502 mi->sample_tries = 1; 503 mi->sample_count--; 504 } 505 506 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) 507 mi->sample_packets += info->status.ampdu_len; 508 509 last = !minstrel_ht_txstat_valid(mp, &ar[0]); 510 for (i = 0; !last; i++) { 511 last = (i == IEEE80211_TX_MAX_RATES - 1) || 512 !minstrel_ht_txstat_valid(mp, &ar[i + 1]); 513 514 rate = minstrel_ht_get_stats(mp, mi, &ar[i]); 515 516 if (last) 517 rate->success += info->status.ampdu_ack_len; 518 519 rate->attempts += ar[i].count * info->status.ampdu_len; 520 } 521 522 /* 523 * check for sudden death of spatial multiplexing, 524 * downgrade to a lower number of streams if necessary. 525 */ 526 rate = minstrel_get_ratestats(mi, mi->max_tp_rate); 527 if (rate->attempts > 30 && 528 MINSTREL_FRAC(rate->success, rate->attempts) < 529 MINSTREL_FRAC(20, 100)) { 530 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true); 531 update = true; 532 } 533 534 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2); 535 if (rate2->attempts > 30 && 536 MINSTREL_FRAC(rate2->success, rate2->attempts) < 537 MINSTREL_FRAC(20, 100)) { 538 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false); 539 update = true; 540 } 541 542 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) { 543 update = true; 544 minstrel_ht_update_stats(mp, mi); 545 if (!(info->flags & IEEE80211_TX_CTL_AMPDU) && 546 mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) 547 minstrel_aggr_check(sta, skb); 548 } 549 550 if (update) 551 minstrel_ht_update_rates(mp, mi); 552 } 553 554 static void 555 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 556 int index) 557 { 558 struct minstrel_rate_stats *mr; 559 const struct mcs_group *group; 560 unsigned int tx_time, tx_time_rtscts, tx_time_data; 561 unsigned int cw = mp->cw_min; 562 unsigned int ctime = 0; 563 unsigned int t_slot = 9; /* FIXME */ 564 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len); 565 unsigned int overhead = 0, overhead_rtscts = 0; 566 567 mr = minstrel_get_ratestats(mi, index); 568 if (mr->probability < MINSTREL_FRAC(1, 10)) { 569 mr->retry_count = 1; 570 mr->retry_count_rtscts = 1; 571 return; 572 } 573 574 mr->retry_count = 2; 575 mr->retry_count_rtscts = 2; 576 mr->retry_updated = true; 577 578 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES]; 579 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000; 580 581 /* Contention time for first 2 tries */ 582 ctime = (t_slot * cw) >> 1; 583 cw = min((cw << 1) | 1, mp->cw_max); 584 ctime += (t_slot * cw) >> 1; 585 cw = min((cw << 1) | 1, mp->cw_max); 586 587 if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) { 588 overhead = mi->overhead; 589 overhead_rtscts = mi->overhead_rtscts; 590 } 591 592 /* Total TX time for data and Contention after first 2 tries */ 593 tx_time = ctime + 2 * (overhead + tx_time_data); 594 tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data); 595 596 /* See how many more tries we can fit inside segment size */ 597 do { 598 /* Contention time for this try */ 599 ctime = (t_slot * cw) >> 1; 600 cw = min((cw << 1) | 1, mp->cw_max); 601 602 /* Total TX time after this try */ 603 tx_time += ctime + overhead + tx_time_data; 604 tx_time_rtscts += ctime + overhead_rtscts + tx_time_data; 605 606 if (tx_time_rtscts < mp->segment_size) 607 mr->retry_count_rtscts++; 608 } while ((tx_time < mp->segment_size) && 609 (++mr->retry_count < mp->max_retry)); 610 } 611 612 613 static void 614 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 615 struct ieee80211_sta_rates *ratetbl, int offset, int index) 616 { 617 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES]; 618 struct minstrel_rate_stats *mr; 619 u8 idx; 620 u16 flags; 621 622 mr = minstrel_get_ratestats(mi, index); 623 if (!mr->retry_updated) 624 minstrel_calc_retransmit(mp, mi, index); 625 626 if (mr->probability < MINSTREL_FRAC(20, 100) || !mr->retry_count) { 627 ratetbl->rate[offset].count = 2; 628 ratetbl->rate[offset].count_rts = 2; 629 ratetbl->rate[offset].count_cts = 2; 630 } else { 631 ratetbl->rate[offset].count = mr->retry_count; 632 ratetbl->rate[offset].count_cts = mr->retry_count; 633 ratetbl->rate[offset].count_rts = mr->retry_count_rtscts; 634 } 635 636 if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) { 637 idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)]; 638 flags = 0; 639 } else { 640 idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8; 641 flags = IEEE80211_TX_RC_MCS | group->flags; 642 } 643 644 if (offset > 0) { 645 ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts; 646 flags |= IEEE80211_TX_RC_USE_RTS_CTS; 647 } 648 649 ratetbl->rate[offset].idx = idx; 650 ratetbl->rate[offset].flags = flags; 651 } 652 653 static void 654 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) 655 { 656 struct ieee80211_sta_rates *rates; 657 int i = 0; 658 659 rates = kzalloc(sizeof(*rates), GFP_ATOMIC); 660 if (!rates) 661 return; 662 663 /* Start with max_tp_rate */ 664 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate); 665 666 if (mp->hw->max_rates >= 3) { 667 /* At least 3 tx rates supported, use max_tp_rate2 next */ 668 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate2); 669 } 670 671 if (mp->hw->max_rates >= 2) { 672 /* 673 * At least 2 tx rates supported, use max_prob_rate next */ 674 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate); 675 } 676 677 rates->rate[i].idx = -1; 678 rate_control_set_rates(mp->hw, mi->sta, rates); 679 } 680 681 static inline int 682 minstrel_get_duration(int index) 683 { 684 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES]; 685 return group->duration[index % MCS_GROUP_RATES]; 686 } 687 688 static int 689 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi) 690 { 691 struct minstrel_rate_stats *mr; 692 struct minstrel_mcs_group_data *mg; 693 unsigned int sample_dur, sample_group; 694 int sample_idx = 0; 695 696 if (mi->sample_wait > 0) { 697 mi->sample_wait--; 698 return -1; 699 } 700 701 if (!mi->sample_tries) 702 return -1; 703 704 sample_group = mi->sample_group; 705 mg = &mi->groups[sample_group]; 706 sample_idx = sample_table[mg->column][mg->index]; 707 minstrel_next_sample_idx(mi); 708 709 if (!(mg->supported & BIT(sample_idx))) 710 return -1; 711 712 mr = &mg->rates[sample_idx]; 713 sample_idx += sample_group * MCS_GROUP_RATES; 714 715 /* 716 * Sampling might add some overhead (RTS, no aggregation) 717 * to the frame. Hence, don't use sampling for the currently 718 * used rates. 719 */ 720 if (sample_idx == mi->max_tp_rate || 721 sample_idx == mi->max_tp_rate2 || 722 sample_idx == mi->max_prob_rate) 723 return -1; 724 725 /* 726 * Do not sample if the probability is already higher than 95% 727 * to avoid wasting airtime. 728 */ 729 if (mr->probability > MINSTREL_FRAC(95, 100)) 730 return -1; 731 732 /* 733 * Make sure that lower rates get sampled only occasionally, 734 * if the link is working perfectly. 735 */ 736 sample_dur = minstrel_get_duration(sample_idx); 737 if (sample_dur >= minstrel_get_duration(mi->max_tp_rate2) && 738 (mi->max_prob_streams < 739 minstrel_mcs_groups[sample_group].streams || 740 sample_dur >= minstrel_get_duration(mi->max_prob_rate))) { 741 if (mr->sample_skipped < 20) 742 return -1; 743 744 if (mi->sample_slow++ > 2) 745 return -1; 746 } 747 mi->sample_tries--; 748 749 return sample_idx; 750 } 751 752 static void 753 minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp, 754 struct minstrel_ht_sta *mi, bool val) 755 { 756 u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported; 757 758 if (!supported || !mi->cck_supported_short) 759 return; 760 761 if (supported & (mi->cck_supported_short << (val * 4))) 762 return; 763 764 supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4); 765 mi->groups[MINSTREL_CCK_GROUP].supported = supported; 766 } 767 768 static void 769 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta, 770 struct ieee80211_tx_rate_control *txrc) 771 { 772 const struct mcs_group *sample_group; 773 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb); 774 struct ieee80211_tx_rate *rate = &info->status.rates[0]; 775 struct minstrel_ht_sta_priv *msp = priv_sta; 776 struct minstrel_ht_sta *mi = &msp->ht; 777 struct minstrel_priv *mp = priv; 778 int sample_idx; 779 780 if (rate_control_send_low(sta, priv_sta, txrc)) 781 return; 782 783 if (!msp->is_ht) 784 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc); 785 786 info->flags |= mi->tx_flags; 787 minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble); 788 789 #ifdef CONFIG_MAC80211_DEBUGFS 790 if (mp->fixed_rate_idx != -1) 791 return; 792 #endif 793 794 /* Don't use EAPOL frames for sampling on non-mrr hw */ 795 if (mp->hw->max_rates == 1 && 796 (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO)) 797 sample_idx = -1; 798 else 799 sample_idx = minstrel_get_sample_rate(mp, mi); 800 801 mi->total_packets++; 802 803 /* wraparound */ 804 if (mi->total_packets == ~0) { 805 mi->total_packets = 0; 806 mi->sample_packets = 0; 807 } 808 809 if (sample_idx < 0) 810 return; 811 812 sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES]; 813 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE; 814 rate->count = 1; 815 816 if (sample_idx / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) { 817 int idx = sample_idx % ARRAY_SIZE(mp->cck_rates); 818 rate->idx = mp->cck_rates[idx]; 819 rate->flags = 0; 820 return; 821 } 822 823 rate->idx = sample_idx % MCS_GROUP_RATES + 824 (sample_group->streams - 1) * 8; 825 rate->flags = IEEE80211_TX_RC_MCS | sample_group->flags; 826 } 827 828 static void 829 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi, 830 struct ieee80211_supported_band *sband, 831 struct ieee80211_sta *sta) 832 { 833 int i; 834 835 if (sband->band != IEEE80211_BAND_2GHZ) 836 return; 837 838 if (!(mp->hw->flags & IEEE80211_HW_SUPPORTS_HT_CCK_RATES)) 839 return; 840 841 mi->cck_supported = 0; 842 mi->cck_supported_short = 0; 843 for (i = 0; i < 4; i++) { 844 if (!rate_supported(sta, sband->band, mp->cck_rates[i])) 845 continue; 846 847 mi->cck_supported |= BIT(i); 848 if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE) 849 mi->cck_supported_short |= BIT(i); 850 } 851 852 mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported; 853 } 854 855 static void 856 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband, 857 struct cfg80211_chan_def *chandef, 858 struct ieee80211_sta *sta, void *priv_sta) 859 { 860 struct minstrel_priv *mp = priv; 861 struct minstrel_ht_sta_priv *msp = priv_sta; 862 struct minstrel_ht_sta *mi = &msp->ht; 863 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs; 864 u16 sta_cap = sta->ht_cap.cap; 865 int n_supported = 0; 866 int ack_dur; 867 int stbc; 868 int i; 869 870 /* fall back to the old minstrel for legacy stations */ 871 if (!sta->ht_cap.ht_supported) 872 goto use_legacy; 873 874 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != 875 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1); 876 877 msp->is_ht = true; 878 memset(mi, 0, sizeof(*mi)); 879 880 mi->sta = sta; 881 mi->stats_update = jiffies; 882 883 ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0); 884 mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0); 885 mi->overhead += ack_dur; 886 mi->overhead_rtscts = mi->overhead + 2 * ack_dur; 887 888 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1); 889 890 /* When using MRR, sample more on the first attempt, without delay */ 891 if (mp->has_mrr) { 892 mi->sample_count = 16; 893 mi->sample_wait = 0; 894 } else { 895 mi->sample_count = 8; 896 mi->sample_wait = 8; 897 } 898 mi->sample_tries = 4; 899 900 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >> 901 IEEE80211_HT_CAP_RX_STBC_SHIFT; 902 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT; 903 904 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING) 905 mi->tx_flags |= IEEE80211_TX_CTL_LDPC; 906 907 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) { 908 mi->groups[i].supported = 0; 909 if (i == MINSTREL_CCK_GROUP) { 910 minstrel_ht_update_cck(mp, mi, sband, sta); 911 continue; 912 } 913 914 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) { 915 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) { 916 if (!(sta_cap & IEEE80211_HT_CAP_SGI_40)) 917 continue; 918 } else { 919 if (!(sta_cap & IEEE80211_HT_CAP_SGI_20)) 920 continue; 921 } 922 } 923 924 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH && 925 sta->bandwidth < IEEE80211_STA_RX_BW_40) 926 continue; 927 928 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */ 929 if (sta->smps_mode == IEEE80211_SMPS_STATIC && 930 minstrel_mcs_groups[i].streams > 1) 931 continue; 932 933 mi->groups[i].supported = 934 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1]; 935 936 if (mi->groups[i].supported) 937 n_supported++; 938 } 939 940 if (!n_supported) 941 goto use_legacy; 942 943 /* create an initial rate table with the lowest supported rates */ 944 minstrel_ht_update_stats(mp, mi); 945 minstrel_ht_update_rates(mp, mi); 946 947 return; 948 949 use_legacy: 950 msp->is_ht = false; 951 memset(&msp->legacy, 0, sizeof(msp->legacy)); 952 msp->legacy.r = msp->ratelist; 953 msp->legacy.sample_table = msp->sample_table; 954 return mac80211_minstrel.rate_init(priv, sband, chandef, sta, 955 &msp->legacy); 956 } 957 958 static void 959 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband, 960 struct cfg80211_chan_def *chandef, 961 struct ieee80211_sta *sta, void *priv_sta) 962 { 963 minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta); 964 } 965 966 static void 967 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband, 968 struct cfg80211_chan_def *chandef, 969 struct ieee80211_sta *sta, void *priv_sta, 970 u32 changed) 971 { 972 minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta); 973 } 974 975 static void * 976 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp) 977 { 978 struct ieee80211_supported_band *sband; 979 struct minstrel_ht_sta_priv *msp; 980 struct minstrel_priv *mp = priv; 981 struct ieee80211_hw *hw = mp->hw; 982 int max_rates = 0; 983 int i; 984 985 for (i = 0; i < IEEE80211_NUM_BANDS; i++) { 986 sband = hw->wiphy->bands[i]; 987 if (sband && sband->n_bitrates > max_rates) 988 max_rates = sband->n_bitrates; 989 } 990 991 msp = kzalloc(sizeof(*msp), gfp); 992 if (!msp) 993 return NULL; 994 995 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp); 996 if (!msp->ratelist) 997 goto error; 998 999 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp); 1000 if (!msp->sample_table) 1001 goto error1; 1002 1003 return msp; 1004 1005 error1: 1006 kfree(msp->ratelist); 1007 error: 1008 kfree(msp); 1009 return NULL; 1010 } 1011 1012 static void 1013 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta) 1014 { 1015 struct minstrel_ht_sta_priv *msp = priv_sta; 1016 1017 kfree(msp->sample_table); 1018 kfree(msp->ratelist); 1019 kfree(msp); 1020 } 1021 1022 static void * 1023 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir) 1024 { 1025 return mac80211_minstrel.alloc(hw, debugfsdir); 1026 } 1027 1028 static void 1029 minstrel_ht_free(void *priv) 1030 { 1031 mac80211_minstrel.free(priv); 1032 } 1033 1034 static const struct rate_control_ops mac80211_minstrel_ht = { 1035 .name = "minstrel_ht", 1036 .tx_status = minstrel_ht_tx_status, 1037 .get_rate = minstrel_ht_get_rate, 1038 .rate_init = minstrel_ht_rate_init, 1039 .rate_update = minstrel_ht_rate_update, 1040 .alloc_sta = minstrel_ht_alloc_sta, 1041 .free_sta = minstrel_ht_free_sta, 1042 .alloc = minstrel_ht_alloc, 1043 .free = minstrel_ht_free, 1044 #ifdef CONFIG_MAC80211_DEBUGFS 1045 .add_sta_debugfs = minstrel_ht_add_sta_debugfs, 1046 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs, 1047 #endif 1048 }; 1049 1050 1051 static void __init init_sample_table(void) 1052 { 1053 int col, i, new_idx; 1054 u8 rnd[MCS_GROUP_RATES]; 1055 1056 memset(sample_table, 0xff, sizeof(sample_table)); 1057 for (col = 0; col < SAMPLE_COLUMNS; col++) { 1058 prandom_bytes(rnd, sizeof(rnd)); 1059 for (i = 0; i < MCS_GROUP_RATES; i++) { 1060 new_idx = (i + rnd[i]) % MCS_GROUP_RATES; 1061 while (sample_table[col][new_idx] != 0xff) 1062 new_idx = (new_idx + 1) % MCS_GROUP_RATES; 1063 1064 sample_table[col][new_idx] = i; 1065 } 1066 } 1067 } 1068 1069 int __init 1070 rc80211_minstrel_ht_init(void) 1071 { 1072 init_sample_table(); 1073 return ieee80211_rate_control_register(&mac80211_minstrel_ht); 1074 } 1075 1076 void 1077 rc80211_minstrel_ht_exit(void) 1078 { 1079 ieee80211_rate_control_unregister(&mac80211_minstrel_ht); 1080 } 1081