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Add linux-next specific files for 20110615
[linux-2.6/next.git] / net / mac80211 / rc80211_minstrel_ht.c
blob66a1eeb279c697f1fc11f0bc0ef17f5fbcd0d40b
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 /* MCS rate information for an MCS group */
40 #define MCS_GROUP(_streams, _sgi, _ht40) { \
41 .streams = _streams, \
42 .flags = \
43 (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
44 (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
45 .duration = { \
46 MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \
47 MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \
48 MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \
49 MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \
50 MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \
51 MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \
52 MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \
53 MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \
54 } \
55 }
56
57 /*
58 * To enable sufficiently targeted rate sampling, MCS rates are divided into
59 * groups, based on the number of streams and flags (HT40, SGI) that they
60 * use.
61 */
62 const struct mcs_group minstrel_mcs_groups[] = {
63 MCS_GROUP(1, 0, 0),
64 MCS_GROUP(2, 0, 0),
65 #if MINSTREL_MAX_STREAMS >= 3
66 MCS_GROUP(3, 0, 0),
67 #endif
68
69 MCS_GROUP(1, 1, 0),
70 MCS_GROUP(2, 1, 0),
71 #if MINSTREL_MAX_STREAMS >= 3
72 MCS_GROUP(3, 1, 0),
73 #endif
74
75 MCS_GROUP(1, 0, 1),
76 MCS_GROUP(2, 0, 1),
77 #if MINSTREL_MAX_STREAMS >= 3
78 MCS_GROUP(3, 0, 1),
79 #endif
80
81 MCS_GROUP(1, 1, 1),
82 MCS_GROUP(2, 1, 1),
83 #if MINSTREL_MAX_STREAMS >= 3
84 MCS_GROUP(3, 1, 1),
85 #endif
86 };
87
88 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
89
90 /*
91 * Perform EWMA (Exponentially Weighted Moving Average) calculation
92 */
93 static int
94 minstrel_ewma(int old, int new, int weight)
95 {
96 return (new * (100 - weight) + old * weight) / 100;
97 }
98
99 /*
100 * Look up an MCS group index based on mac80211 rate information
101 */
102 static int
103 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
104 {
105 int streams = (rate->idx / MCS_GROUP_RATES) + 1;
106 u32 flags = IEEE80211_TX_RC_SHORT_GI | IEEE80211_TX_RC_40_MHZ_WIDTH;
107 int i;
108
109 for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
110 if (minstrel_mcs_groups[i].streams != streams)
111 continue;
112 if (minstrel_mcs_groups[i].flags != (rate->flags & flags))
113 continue;
114
115 return i;
116 }
117
118 WARN_ON(1);
119 return 0;
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_priv *mp, 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_priv *mp, struct minstrel_ht_sta *mi,
160 int group, int rate)
161 {
162 struct minstrel_rate_stats *mr;
163 unsigned int usecs;
164
165 mr = &mi->groups[group].rates[rate];
166
167 if (mr->probability < MINSTREL_FRAC(1, 10)) {
168 mr->cur_tp = 0;
169 return;
170 }
171
172 usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
173 usecs += minstrel_mcs_groups[group].duration[rate];
174 mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
175 }
176
177 /*
178 * Update rate statistics and select new primary rates
179 *
180 * Rules for rate selection:
181 * - max_prob_rate must use only one stream, as a tradeoff between delivery
182 * probability and throughput during strong fluctuations
183 * - as long as the max prob rate has a probability of more than 3/4, pick
184 * higher throughput rates, even if the probablity is a bit lower
185 */
186 static void
187 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
188 {
189 struct minstrel_mcs_group_data *mg;
190 struct minstrel_rate_stats *mr;
191 int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
192 int group, i, index;
193
194 if (mi->ampdu_packets > 0) {
195 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
196 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
197 mi->ampdu_len = 0;
198 mi->ampdu_packets = 0;
199 }
200
201 mi->sample_slow = 0;
202 mi->sample_count = 0;
203 mi->max_tp_rate = 0;
204 mi->max_tp_rate2 = 0;
205 mi->max_prob_rate = 0;
206
207 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
208 cur_prob = 0;
209 cur_prob_tp = 0;
210 cur_tp = 0;
211 cur_tp2 = 0;
212
213 mg = &mi->groups[group];
214 if (!mg->supported)
215 continue;
216
217 mg->max_tp_rate = 0;
218 mg->max_tp_rate2 = 0;
219 mg->max_prob_rate = 0;
220 mi->sample_count++;
221
222 for (i = 0; i < MCS_GROUP_RATES; i++) {
223 if (!(mg->supported & BIT(i)))
224 continue;
225
226 mr = &mg->rates[i];
227 mr->retry_updated = false;
228 index = MCS_GROUP_RATES * group + i;
229 minstrel_calc_rate_ewma(mp, mr);
230 minstrel_ht_calc_tp(mp, mi, group, i);
231
232 if (!mr->cur_tp)
233 continue;
234
235 /* ignore the lowest rate of each single-stream group */
236 if (!i && minstrel_mcs_groups[group].streams == 1)
237 continue;
238
239 if ((mr->cur_tp > cur_prob_tp && mr->probability >
240 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
241 mg->max_prob_rate = index;
242 cur_prob = mr->probability;
243 cur_prob_tp = mr->cur_tp;
244 }
245
246 if (mr->cur_tp > cur_tp) {
247 swap(index, mg->max_tp_rate);
248 cur_tp = mr->cur_tp;
249 mr = minstrel_get_ratestats(mi, index);
250 }
251
252 if (index >= mg->max_tp_rate)
253 continue;
254
255 if (mr->cur_tp > cur_tp2) {
256 mg->max_tp_rate2 = index;
257 cur_tp2 = mr->cur_tp;
258 }
259 }
260 }
261
262 /* try to sample up to half of the available rates during each interval */
263 mi->sample_count *= 4;
264
265 cur_prob = 0;
266 cur_prob_tp = 0;
267 cur_tp = 0;
268 cur_tp2 = 0;
269 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
270 mg = &mi->groups[group];
271 if (!mg->supported)
272 continue;
273
274 mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
275 if (cur_prob_tp < mr->cur_tp &&
276 minstrel_mcs_groups[group].streams == 1) {
277 mi->max_prob_rate = mg->max_prob_rate;
278 cur_prob = mr->cur_prob;
279 cur_prob_tp = mr->cur_tp;
280 }
281
282 mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
283 if (cur_tp < mr->cur_tp) {
284 mi->max_tp_rate = mg->max_tp_rate;
285 cur_tp = mr->cur_tp;
286 }
287
288 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
289 if (cur_tp2 < mr->cur_tp) {
290 mi->max_tp_rate2 = mg->max_tp_rate2;
291 cur_tp2 = mr->cur_tp;
292 }
293 }
294
295 mi->stats_update = jiffies;
296 }
297
298 static bool
299 minstrel_ht_txstat_valid(struct ieee80211_tx_rate *rate)
300 {
301 if (!rate->count)
302 return false;
303
304 if (rate->idx < 0)
305 return false;
306
307 return !!(rate->flags & IEEE80211_TX_RC_MCS);
308 }
309
310 static void
311 minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
312 {
313 struct minstrel_mcs_group_data *mg;
314
315 for (;;) {
316 mi->sample_group++;
317 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
318 mg = &mi->groups[mi->sample_group];
319
320 if (!mg->supported)
321 continue;
322
323 if (++mg->index >= MCS_GROUP_RATES) {
324 mg->index = 0;
325 if (++mg->column >= ARRAY_SIZE(sample_table))
326 mg->column = 0;
327 }
328 break;
329 }
330 }
331
332 static void
333 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
334 bool primary)
335 {
336 int group, orig_group;
337
338 orig_group = group = *idx / MCS_GROUP_RATES;
339 while (group > 0) {
340 group--;
341
342 if (!mi->groups[group].supported)
343 continue;
344
345 if (minstrel_mcs_groups[group].streams >
346 minstrel_mcs_groups[orig_group].streams)
347 continue;
348
349 if (primary)
350 *idx = mi->groups[group].max_tp_rate;
351 else
352 *idx = mi->groups[group].max_tp_rate2;
353 break;
354 }
355 }
356
357 static void
358 minstrel_aggr_check(struct minstrel_priv *mp, struct ieee80211_sta *pubsta, struct sk_buff *skb)
359 {
360 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
361 struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
362 u16 tid;
363
364 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
365 return;
366
367 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
368 return;
369
370 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
371 if (likely(sta->ampdu_mlme.tid_tx[tid]))
372 return;
373
374 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
375 return;
376
377 ieee80211_start_tx_ba_session(pubsta, tid, 5000);
378 }
379
380 static void
381 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
382 struct ieee80211_sta *sta, void *priv_sta,
383 struct sk_buff *skb)
384 {
385 struct minstrel_ht_sta_priv *msp = priv_sta;
386 struct minstrel_ht_sta *mi = &msp->ht;
387 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
388 struct ieee80211_tx_rate *ar = info->status.rates;
389 struct minstrel_rate_stats *rate, *rate2;
390 struct minstrel_priv *mp = priv;
391 bool last = false;
392 int group;
393 int i = 0;
394
395 if (!msp->is_ht)
396 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
397
398 /* This packet was aggregated but doesn't carry status info */
399 if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
400 !(info->flags & IEEE80211_TX_STAT_AMPDU))
401 return;
402
403 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
404 info->status.ampdu_ack_len =
405 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
406 info->status.ampdu_len = 1;
407 }
408
409 mi->ampdu_packets++;
410 mi->ampdu_len += info->status.ampdu_len;
411
412 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
413 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
414 mi->sample_tries = 2;
415 mi->sample_count--;
416 }
417
418 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
419 mi->sample_packets += info->status.ampdu_len;
420
421 for (i = 0; !last; i++) {
422 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
423 !minstrel_ht_txstat_valid(&ar[i + 1]);
424
425 if (!minstrel_ht_txstat_valid(&ar[i]))
426 break;
427
428 group = minstrel_ht_get_group_idx(&ar[i]);
429 rate = &mi->groups[group].rates[ar[i].idx % 8];
430
431 if (last)
432 rate->success += info->status.ampdu_ack_len;
433
434 rate->attempts += ar[i].count * info->status.ampdu_len;
435 }
436
437 /*
438 * check for sudden death of spatial multiplexing,
439 * downgrade to a lower number of streams if necessary.
440 */
441 rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
442 if (rate->attempts > 30 &&
443 MINSTREL_FRAC(rate->success, rate->attempts) <
444 MINSTREL_FRAC(20, 100))
445 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
446
447 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
448 if (rate2->attempts > 30 &&
449 MINSTREL_FRAC(rate2->success, rate2->attempts) <
450 MINSTREL_FRAC(20, 100))
451 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
452
453 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
454 minstrel_ht_update_stats(mp, mi);
455 minstrel_aggr_check(mp, 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 struct ieee80211_tx_rate_control *txrc,
516 bool sample, bool rtscts)
517 {
518 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
519 struct minstrel_rate_stats *mr;
520
521 mr = minstrel_get_ratestats(mi, index);
522 if (!mr->retry_updated)
523 minstrel_calc_retransmit(mp, mi, index);
524
525 if (sample)
526 rate->count = 1;
527 else if (mr->probability < MINSTREL_FRAC(20, 100))
528 rate->count = 2;
529 else if (rtscts)
530 rate->count = mr->retry_count_rtscts;
531 else
532 rate->count = mr->retry_count;
533
534 rate->flags = IEEE80211_TX_RC_MCS | group->flags;
535 if (rtscts)
536 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
537 rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
538 }
539
540 static inline int
541 minstrel_get_duration(int index)
542 {
543 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
544 return group->duration[index % MCS_GROUP_RATES];
545 }
546
547 static int
548 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
549 {
550 struct minstrel_rate_stats *mr;
551 struct minstrel_mcs_group_data *mg;
552 int sample_idx = 0;
553
554 if (mi->sample_wait > 0) {
555 mi->sample_wait--;
556 return -1;
557 }
558
559 if (!mi->sample_tries)
560 return -1;
561
562 mi->sample_tries--;
563 mg = &mi->groups[mi->sample_group];
564 sample_idx = sample_table[mg->column][mg->index];
565 mr = &mg->rates[sample_idx];
566 sample_idx += mi->sample_group * MCS_GROUP_RATES;
567 minstrel_next_sample_idx(mi);
568
569 /*
570 * When not using MRR, do not sample if the probability is already
571 * higher than 95% to avoid wasting airtime
572 */
573 if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
574 return -1;
575
576 /*
577 * Make sure that lower rates get sampled only occasionally,
578 * if the link is working perfectly.
579 */
580 if (minstrel_get_duration(sample_idx) >
581 minstrel_get_duration(mi->max_tp_rate)) {
582 if (mr->sample_skipped < 20)
583 return -1;
584
585 if (mi->sample_slow++ > 2)
586 return -1;
587 }
588
589 return sample_idx;
590 }
591
592 static void
593 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
594 struct ieee80211_tx_rate_control *txrc)
595 {
596 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
597 struct ieee80211_tx_rate *ar = info->status.rates;
598 struct minstrel_ht_sta_priv *msp = priv_sta;
599 struct minstrel_ht_sta *mi = &msp->ht;
600 struct minstrel_priv *mp = priv;
601 int sample_idx;
602 bool sample = false;
603
604 if (rate_control_send_low(sta, priv_sta, txrc))
605 return;
606
607 if (!msp->is_ht)
608 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
609
610 info->flags |= mi->tx_flags;
611 sample_idx = minstrel_get_sample_rate(mp, mi);
612
613 #ifdef CONFIG_MAC80211_DEBUGFS
614 /* use fixed index if set */
615 if (mp->fixed_rate_idx != -1)
616 sample_idx = mp->fixed_rate_idx;
617 #endif
618
619 if (sample_idx >= 0) {
620 sample = true;
621 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
622 txrc, true, false);
623 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
624 } else {
625 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
626 txrc, false, false);
627 }
628
629 if (mp->hw->max_rates >= 3) {
630 /*
631 * At least 3 tx rates supported, use
632 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
633 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
634 */
635 if (sample_idx >= 0)
636 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
637 txrc, false, false);
638 else
639 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
640 txrc, false, true);
641
642 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
643 txrc, false, !sample);
644
645 ar[3].count = 0;
646 ar[3].idx = -1;
647 } else if (mp->hw->max_rates == 2) {
648 /*
649 * Only 2 tx rates supported, use
650 * sample_rate -> max_prob_rate for sampling and
651 * max_tp_rate -> max_prob_rate by default.
652 */
653 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
654 txrc, false, !sample);
655
656 ar[2].count = 0;
657 ar[2].idx = -1;
658 } else {
659 /* Not using MRR, only use the first rate */
660 ar[1].count = 0;
661 ar[1].idx = -1;
662 }
663
664 mi->total_packets++;
665
666 /* wraparound */
667 if (mi->total_packets == ~0) {
668 mi->total_packets = 0;
669 mi->sample_packets = 0;
670 }
671 }
672
673 static void
674 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
675 struct ieee80211_sta *sta, void *priv_sta,
676 enum nl80211_channel_type oper_chan_type)
677 {
678 struct minstrel_priv *mp = priv;
679 struct minstrel_ht_sta_priv *msp = priv_sta;
680 struct minstrel_ht_sta *mi = &msp->ht;
681 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
682 struct ieee80211_local *local = hw_to_local(mp->hw);
683 u16 sta_cap = sta->ht_cap.cap;
684 int n_supported = 0;
685 int ack_dur;
686 int stbc;
687 int i;
688
689 /* fall back to the old minstrel for legacy stations */
690 if (!sta->ht_cap.ht_supported)
691 goto use_legacy;
692
693 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
694 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
695
696 msp->is_ht = true;
697 memset(mi, 0, sizeof(*mi));
698 mi->stats_update = jiffies;
699
700 ack_dur = ieee80211_frame_duration(local, 10, 60, 1, 1);
701 mi->overhead = ieee80211_frame_duration(local, 0, 60, 1, 1) + ack_dur;
702 mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
703
704 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
705
706 /* When using MRR, sample more on the first attempt, without delay */
707 if (mp->has_mrr) {
708 mi->sample_count = 16;
709 mi->sample_wait = 0;
710 } else {
711 mi->sample_count = 8;
712 mi->sample_wait = 8;
713 }
714 mi->sample_tries = 4;
715
716 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
717 IEEE80211_HT_CAP_RX_STBC_SHIFT;
718 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
719
720 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
721 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
722
723 if (oper_chan_type != NL80211_CHAN_HT40MINUS &&
724 oper_chan_type != NL80211_CHAN_HT40PLUS)
725 sta_cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
726
727 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
728 u16 req = 0;
729
730 mi->groups[i].supported = 0;
731 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
732 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
733 req |= IEEE80211_HT_CAP_SGI_40;
734 else
735 req |= IEEE80211_HT_CAP_SGI_20;
736 }
737
738 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
739 req |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
740
741 if ((sta_cap & req) != req)
742 continue;
743
744 mi->groups[i].supported =
745 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
746
747 if (mi->groups[i].supported)
748 n_supported++;
749 }
750
751 if (!n_supported)
752 goto use_legacy;
753
754 return;
755
756 use_legacy:
757 msp->is_ht = false;
758 memset(&msp->legacy, 0, sizeof(msp->legacy));
759 msp->legacy.r = msp->ratelist;
760 msp->legacy.sample_table = msp->sample_table;
761 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
762 }
763
764 static void
765 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
766 struct ieee80211_sta *sta, void *priv_sta)
767 {
768 struct minstrel_priv *mp = priv;
769
770 minstrel_ht_update_caps(priv, sband, sta, priv_sta, mp->hw->conf.channel_type);
771 }
772
773 static void
774 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
775 struct ieee80211_sta *sta, void *priv_sta,
776 u32 changed, enum nl80211_channel_type oper_chan_type)
777 {
778 minstrel_ht_update_caps(priv, sband, sta, priv_sta, oper_chan_type);
779 }
780
781 static void *
782 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
783 {
784 struct ieee80211_supported_band *sband;
785 struct minstrel_ht_sta_priv *msp;
786 struct minstrel_priv *mp = priv;
787 struct ieee80211_hw *hw = mp->hw;
788 int max_rates = 0;
789 int i;
790
791 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
792 sband = hw->wiphy->bands[i];
793 if (sband && sband->n_bitrates > max_rates)
794 max_rates = sband->n_bitrates;
795 }
796
797 msp = kzalloc(sizeof(struct minstrel_ht_sta), gfp);
798 if (!msp)
799 return NULL;
800
801 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
802 if (!msp->ratelist)
803 goto error;
804
805 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
806 if (!msp->sample_table)
807 goto error1;
808
809 return msp;
810
811 error1:
812 kfree(msp->ratelist);
813 error:
814 kfree(msp);
815 return NULL;
816 }
817
818 static void
819 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
820 {
821 struct minstrel_ht_sta_priv *msp = priv_sta;
822
823 kfree(msp->sample_table);
824 kfree(msp->ratelist);
825 kfree(msp);
826 }
827
828 static void *
829 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
830 {
831 return mac80211_minstrel.alloc(hw, debugfsdir);
832 }
833
834 static void
835 minstrel_ht_free(void *priv)
836 {
837 mac80211_minstrel.free(priv);
838 }
839
840 static struct rate_control_ops mac80211_minstrel_ht = {
841 .name = "minstrel_ht",
842 .tx_status = minstrel_ht_tx_status,
843 .get_rate = minstrel_ht_get_rate,
844 .rate_init = minstrel_ht_rate_init,
845 .rate_update = minstrel_ht_rate_update,
846 .alloc_sta = minstrel_ht_alloc_sta,
847 .free_sta = minstrel_ht_free_sta,
848 .alloc = minstrel_ht_alloc,
849 .free = minstrel_ht_free,
850 #ifdef CONFIG_MAC80211_DEBUGFS
851 .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
852 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
853 #endif
854 };
855
856
857 static void
858 init_sample_table(void)
859 {
860 int col, i, new_idx;
861 u8 rnd[MCS_GROUP_RATES];
862
863 memset(sample_table, 0xff, sizeof(sample_table));
864 for (col = 0; col < SAMPLE_COLUMNS; col++) {
865 for (i = 0; i < MCS_GROUP_RATES; i++) {
866 get_random_bytes(rnd, sizeof(rnd));
867 new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
868
869 while (sample_table[col][new_idx] != 0xff)
870 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
871
872 sample_table[col][new_idx] = i;
873 }
874 }
875 }
876
877 int __init
878 rc80211_minstrel_ht_init(void)
879 {
880 init_sample_table();
881 return ieee80211_rate_control_register(&mac80211_minstrel_ht);
882 }
883
884 void
885 rc80211_minstrel_ht_exit(void)
886 {
887 ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
888 }
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