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[media] V4L2: add temporary clock helpers
[linux-2.6.git] / net / mac80211 / rc80211_minstrel_ht.c
blob5b2d3012b9830aef8d9101c26ba761402993b382
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];
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 / MCS_GROUP_RATES) + 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 % MCS_GROUP_RATES;
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 * ((mr->probability * 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 /* initialize rates selections starting indexes */
281 if (!mg_rates_valid) {
282 mg->max_tp_rate = mg->max_tp_rate2 =
283 mg->max_prob_rate = i;
284 if (!mi_rates_valid) {
285 mi->max_tp_rate = mi->max_tp_rate2 =
286 mi->max_prob_rate = i;
287 mi_rates_valid = true;
288 }
289 mg_rates_valid = true;
290 }
291
292 mr = &mg->rates[i];
293 mr->retry_updated = false;
294 index = MCS_GROUP_RATES * group + i;
295 minstrel_calc_rate_ewma(mr);
296 minstrel_ht_calc_tp(mi, group, i);
297
298 if (!mr->cur_tp)
299 continue;
300
301 if ((mr->cur_tp > cur_prob_tp && mr->probability >
302 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
303 mg->max_prob_rate = index;
304 cur_prob = mr->probability;
305 cur_prob_tp = mr->cur_tp;
306 }
307
308 if (mr->cur_tp > cur_tp) {
309 swap(index, mg->max_tp_rate);
310 cur_tp = mr->cur_tp;
311 mr = minstrel_get_ratestats(mi, index);
312 }
313
314 if (index >= mg->max_tp_rate)
315 continue;
316
317 if (mr->cur_tp > cur_tp2) {
318 mg->max_tp_rate2 = index;
319 cur_tp2 = mr->cur_tp;
320 }
321 }
322 }
323
324 /* try to sample all available rates during each interval */
325 mi->sample_count *= 8;
326
327 cur_prob = 0;
328 cur_prob_tp = 0;
329 cur_tp = 0;
330 cur_tp2 = 0;
331 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
332 mg = &mi->groups[group];
333 if (!mg->supported)
334 continue;
335
336 mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
337 if (cur_tp < mr->cur_tp) {
338 mi->max_tp_rate2 = mi->max_tp_rate;
339 cur_tp2 = cur_tp;
340 mi->max_tp_rate = mg->max_tp_rate;
341 cur_tp = mr->cur_tp;
342 mi->max_prob_streams = minstrel_mcs_groups[group].streams - 1;
343 }
344
345 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
346 if (cur_tp2 < mr->cur_tp) {
347 mi->max_tp_rate2 = mg->max_tp_rate2;
348 cur_tp2 = mr->cur_tp;
349 }
350 }
351
352 if (mi->max_prob_streams < 1)
353 mi->max_prob_streams = 1;
354
355 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
356 mg = &mi->groups[group];
357 if (!mg->supported)
358 continue;
359 mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
360 if (cur_prob_tp < mr->cur_tp &&
361 minstrel_mcs_groups[group].streams <= mi->max_prob_streams) {
362 mi->max_prob_rate = mg->max_prob_rate;
363 cur_prob = mr->cur_prob;
364 cur_prob_tp = mr->cur_tp;
365 }
366 }
367
368
369 mi->stats_update = jiffies;
370 }
371
372 static bool
373 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
374 {
375 if (rate->idx < 0)
376 return false;
377
378 if (!rate->count)
379 return false;
380
381 if (rate->flags & IEEE80211_TX_RC_MCS)
382 return true;
383
384 return rate->idx == mp->cck_rates[0] ||
385 rate->idx == mp->cck_rates[1] ||
386 rate->idx == mp->cck_rates[2] ||
387 rate->idx == mp->cck_rates[3];
388 }
389
390 static void
391 minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
392 {
393 struct minstrel_mcs_group_data *mg;
394
395 for (;;) {
396 mi->sample_group++;
397 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
398 mg = &mi->groups[mi->sample_group];
399
400 if (!mg->supported)
401 continue;
402
403 if (++mg->index >= MCS_GROUP_RATES) {
404 mg->index = 0;
405 if (++mg->column >= ARRAY_SIZE(sample_table))
406 mg->column = 0;
407 }
408 break;
409 }
410 }
411
412 static void
413 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
414 bool primary)
415 {
416 int group, orig_group;
417
418 orig_group = group = *idx / MCS_GROUP_RATES;
419 while (group > 0) {
420 group--;
421
422 if (!mi->groups[group].supported)
423 continue;
424
425 if (minstrel_mcs_groups[group].streams >
426 minstrel_mcs_groups[orig_group].streams)
427 continue;
428
429 if (primary)
430 *idx = mi->groups[group].max_tp_rate;
431 else
432 *idx = mi->groups[group].max_tp_rate2;
433 break;
434 }
435 }
436
437 static void
438 minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
439 {
440 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
441 struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
442 u16 tid;
443
444 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
445 return;
446
447 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
448 return;
449
450 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
451 if (likely(sta->ampdu_mlme.tid_tx[tid]))
452 return;
453
454 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
455 return;
456
457 ieee80211_start_tx_ba_session(pubsta, tid, 5000);
458 }
459
460 static void
461 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
462 struct ieee80211_sta *sta, void *priv_sta,
463 struct sk_buff *skb)
464 {
465 struct minstrel_ht_sta_priv *msp = priv_sta;
466 struct minstrel_ht_sta *mi = &msp->ht;
467 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
468 struct ieee80211_tx_rate *ar = info->status.rates;
469 struct minstrel_rate_stats *rate, *rate2;
470 struct minstrel_priv *mp = priv;
471 bool last, update = false;
472 int i;
473
474 if (!msp->is_ht)
475 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
476
477 /* This packet was aggregated but doesn't carry status info */
478 if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
479 !(info->flags & IEEE80211_TX_STAT_AMPDU))
480 return;
481
482 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
483 info->status.ampdu_ack_len =
484 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
485 info->status.ampdu_len = 1;
486 }
487
488 mi->ampdu_packets++;
489 mi->ampdu_len += info->status.ampdu_len;
490
491 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
492 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
493 mi->sample_tries = 1;
494 mi->sample_count--;
495 }
496
497 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
498 mi->sample_packets += info->status.ampdu_len;
499
500 last = !minstrel_ht_txstat_valid(mp, &ar[0]);
501 for (i = 0; !last; i++) {
502 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
503 !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
504
505 rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
506
507 if (last)
508 rate->success += info->status.ampdu_ack_len;
509
510 rate->attempts += ar[i].count * info->status.ampdu_len;
511 }
512
513 /*
514 * check for sudden death of spatial multiplexing,
515 * downgrade to a lower number of streams if necessary.
516 */
517 rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
518 if (rate->attempts > 30 &&
519 MINSTREL_FRAC(rate->success, rate->attempts) <
520 MINSTREL_FRAC(20, 100)) {
521 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
522 update = true;
523 }
524
525 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
526 if (rate2->attempts > 30 &&
527 MINSTREL_FRAC(rate2->success, rate2->attempts) <
528 MINSTREL_FRAC(20, 100)) {
529 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
530 update = true;
531 }
532
533 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
534 update = true;
535 minstrel_ht_update_stats(mp, mi);
536 if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
537 mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
538 minstrel_aggr_check(sta, skb);
539 }
540
541 if (update)
542 minstrel_ht_update_rates(mp, mi);
543 }
544
545 static void
546 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
547 int index)
548 {
549 struct minstrel_rate_stats *mr;
550 const struct mcs_group *group;
551 unsigned int tx_time, tx_time_rtscts, tx_time_data;
552 unsigned int cw = mp->cw_min;
553 unsigned int ctime = 0;
554 unsigned int t_slot = 9; /* FIXME */
555 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
556 unsigned int overhead = 0, overhead_rtscts = 0;
557
558 mr = minstrel_get_ratestats(mi, index);
559 if (mr->probability < MINSTREL_FRAC(1, 10)) {
560 mr->retry_count = 1;
561 mr->retry_count_rtscts = 1;
562 return;
563 }
564
565 mr->retry_count = 2;
566 mr->retry_count_rtscts = 2;
567 mr->retry_updated = true;
568
569 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
570 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
571
572 /* Contention time for first 2 tries */
573 ctime = (t_slot * cw) >> 1;
574 cw = min((cw << 1) | 1, mp->cw_max);
575 ctime += (t_slot * cw) >> 1;
576 cw = min((cw << 1) | 1, mp->cw_max);
577
578 if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
579 overhead = mi->overhead;
580 overhead_rtscts = mi->overhead_rtscts;
581 }
582
583 /* Total TX time for data and Contention after first 2 tries */
584 tx_time = ctime + 2 * (overhead + tx_time_data);
585 tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
586
587 /* See how many more tries we can fit inside segment size */
588 do {
589 /* Contention time for this try */
590 ctime = (t_slot * cw) >> 1;
591 cw = min((cw << 1) | 1, mp->cw_max);
592
593 /* Total TX time after this try */
594 tx_time += ctime + overhead + tx_time_data;
595 tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
596
597 if (tx_time_rtscts < mp->segment_size)
598 mr->retry_count_rtscts++;
599 } while ((tx_time < mp->segment_size) &&
600 (++mr->retry_count < mp->max_retry));
601 }
602
603
604 static void
605 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
606 struct ieee80211_sta_rates *ratetbl, int offset, int index)
607 {
608 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
609 struct minstrel_rate_stats *mr;
610 u8 idx;
611 u16 flags;
612
613 mr = minstrel_get_ratestats(mi, index);
614 if (!mr->retry_updated)
615 minstrel_calc_retransmit(mp, mi, index);
616
617 if (mr->probability < MINSTREL_FRAC(20, 100) || !mr->retry_count) {
618 ratetbl->rate[offset].count = 2;
619 ratetbl->rate[offset].count_rts = 2;
620 ratetbl->rate[offset].count_cts = 2;
621 } else {
622 ratetbl->rate[offset].count = mr->retry_count;
623 ratetbl->rate[offset].count_cts = mr->retry_count;
624 ratetbl->rate[offset].count_rts = mr->retry_count_rtscts;
625 }
626
627 if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
628 idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
629 flags = 0;
630 } else {
631 idx = index % MCS_GROUP_RATES +
632 (group->streams - 1) * MCS_GROUP_RATES;
633 flags = IEEE80211_TX_RC_MCS | group->flags;
634 }
635
636 if (offset > 0) {
637 ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
638 flags |= IEEE80211_TX_RC_USE_RTS_CTS;
639 }
640
641 ratetbl->rate[offset].idx = idx;
642 ratetbl->rate[offset].flags = flags;
643 }
644
645 static void
646 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
647 {
648 struct ieee80211_sta_rates *rates;
649 int i = 0;
650
651 rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
652 if (!rates)
653 return;
654
655 /* Start with max_tp_rate */
656 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate);
657
658 if (mp->hw->max_rates >= 3) {
659 /* At least 3 tx rates supported, use max_tp_rate2 next */
660 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate2);
661 }
662
663 if (mp->hw->max_rates >= 2) {
664 /*
665 * At least 2 tx rates supported, use max_prob_rate next */
666 minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
667 }
668
669 rates->rate[i].idx = -1;
670 rate_control_set_rates(mp->hw, mi->sta, rates);
671 }
672
673 static inline int
674 minstrel_get_duration(int index)
675 {
676 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
677 return group->duration[index % MCS_GROUP_RATES];
678 }
679
680 static int
681 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
682 {
683 struct minstrel_rate_stats *mr;
684 struct minstrel_mcs_group_data *mg;
685 unsigned int sample_dur, sample_group;
686 int sample_idx = 0;
687
688 if (mi->sample_wait > 0) {
689 mi->sample_wait--;
690 return -1;
691 }
692
693 if (!mi->sample_tries)
694 return -1;
695
696 mg = &mi->groups[mi->sample_group];
697 sample_idx = sample_table[mg->column][mg->index];
698 mr = &mg->rates[sample_idx];
699 sample_group = mi->sample_group;
700 sample_idx += sample_group * MCS_GROUP_RATES;
701 minstrel_next_sample_idx(mi);
702
703 /*
704 * Sampling might add some overhead (RTS, no aggregation)
705 * to the frame. Hence, don't use sampling for the currently
706 * used rates.
707 */
708 if (sample_idx == mi->max_tp_rate ||
709 sample_idx == mi->max_tp_rate2 ||
710 sample_idx == mi->max_prob_rate)
711 return -1;
712
713 /*
714 * Do not sample if the probability is already higher than 95%
715 * to avoid wasting airtime.
716 */
717 if (mr->probability > MINSTREL_FRAC(95, 100))
718 return -1;
719
720 /*
721 * Make sure that lower rates get sampled only occasionally,
722 * if the link is working perfectly.
723 */
724 sample_dur = minstrel_get_duration(sample_idx);
725 if (sample_dur >= minstrel_get_duration(mi->max_tp_rate2) &&
726 (mi->max_prob_streams <
727 minstrel_mcs_groups[sample_group].streams ||
728 sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
729 if (mr->sample_skipped < 20)
730 return -1;
731
732 if (mi->sample_slow++ > 2)
733 return -1;
734 }
735 mi->sample_tries--;
736
737 return sample_idx;
738 }
739
740 static void
741 minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
742 struct minstrel_ht_sta *mi, bool val)
743 {
744 u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
745
746 if (!supported || !mi->cck_supported_short)
747 return;
748
749 if (supported & (mi->cck_supported_short << (val * 4)))
750 return;
751
752 supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
753 mi->groups[MINSTREL_CCK_GROUP].supported = supported;
754 }
755
756 static void
757 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
758 struct ieee80211_tx_rate_control *txrc)
759 {
760 const struct mcs_group *sample_group;
761 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
762 struct ieee80211_tx_rate *rate = &info->status.rates[0];
763 struct minstrel_ht_sta_priv *msp = priv_sta;
764 struct minstrel_ht_sta *mi = &msp->ht;
765 struct minstrel_priv *mp = priv;
766 int sample_idx;
767
768 if (rate_control_send_low(sta, priv_sta, txrc))
769 return;
770
771 if (!msp->is_ht)
772 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
773
774 info->flags |= mi->tx_flags;
775 minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
776
777 /* Don't use EAPOL frames for sampling on non-mrr hw */
778 if (mp->hw->max_rates == 1 &&
779 txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
780 sample_idx = -1;
781 else
782 sample_idx = minstrel_get_sample_rate(mp, mi);
783
784 #ifdef CONFIG_MAC80211_DEBUGFS
785 /* use fixed index if set */
786 if (mp->fixed_rate_idx != -1) {
787 mi->max_tp_rate = mp->fixed_rate_idx;
788 mi->max_tp_rate2 = mp->fixed_rate_idx;
789 mi->max_prob_rate = mp->fixed_rate_idx;
790 sample_idx = -1;
791 }
792 #endif
793
794 mi->total_packets++;
795
796 /* wraparound */
797 if (mi->total_packets == ~0) {
798 mi->total_packets = 0;
799 mi->sample_packets = 0;
800 }
801
802 if (sample_idx < 0)
803 return;
804
805 sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
806 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
807 rate->idx = sample_idx % MCS_GROUP_RATES +
808 (sample_group->streams - 1) * MCS_GROUP_RATES;
809 rate->flags = IEEE80211_TX_RC_MCS | sample_group->flags;
810 rate->count = 1;
811 }
812
813 static void
814 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
815 struct ieee80211_supported_band *sband,
816 struct ieee80211_sta *sta)
817 {
818 int i;
819
820 if (sband->band != IEEE80211_BAND_2GHZ)
821 return;
822
823 mi->cck_supported = 0;
824 mi->cck_supported_short = 0;
825 for (i = 0; i < 4; i++) {
826 if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
827 continue;
828
829 mi->cck_supported |= BIT(i);
830 if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
831 mi->cck_supported_short |= BIT(i);
832 }
833
834 mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
835 }
836
837 static void
838 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
839 struct ieee80211_sta *sta, void *priv_sta)
840 {
841 struct minstrel_priv *mp = priv;
842 struct minstrel_ht_sta_priv *msp = priv_sta;
843 struct minstrel_ht_sta *mi = &msp->ht;
844 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
845 u16 sta_cap = sta->ht_cap.cap;
846 int n_supported = 0;
847 int ack_dur;
848 int stbc;
849 int i;
850
851 /* fall back to the old minstrel for legacy stations */
852 if (!sta->ht_cap.ht_supported)
853 goto use_legacy;
854
855 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
856 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
857
858 msp->is_ht = true;
859 memset(mi, 0, sizeof(*mi));
860
861 mi->sta = sta;
862 mi->stats_update = jiffies;
863
864 ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
865 mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
866 mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
867
868 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
869
870 /* When using MRR, sample more on the first attempt, without delay */
871 if (mp->has_mrr) {
872 mi->sample_count = 16;
873 mi->sample_wait = 0;
874 } else {
875 mi->sample_count = 8;
876 mi->sample_wait = 8;
877 }
878 mi->sample_tries = 4;
879
880 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
881 IEEE80211_HT_CAP_RX_STBC_SHIFT;
882 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
883
884 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
885 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
886
887 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
888 mi->groups[i].supported = 0;
889 if (i == MINSTREL_CCK_GROUP) {
890 minstrel_ht_update_cck(mp, mi, sband, sta);
891 continue;
892 }
893
894 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
895 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
896 if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
897 continue;
898 } else {
899 if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
900 continue;
901 }
902 }
903
904 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
905 sta->bandwidth < IEEE80211_STA_RX_BW_40)
906 continue;
907
908 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
909 if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
910 minstrel_mcs_groups[i].streams > 1)
911 continue;
912
913 mi->groups[i].supported =
914 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
915
916 if (mi->groups[i].supported)
917 n_supported++;
918 }
919
920 if (!n_supported)
921 goto use_legacy;
922
923 /* create an initial rate table with the lowest supported rates */
924 minstrel_ht_update_stats(mp, mi);
925 minstrel_ht_update_rates(mp, mi);
926
927 return;
928
929 use_legacy:
930 msp->is_ht = false;
931 memset(&msp->legacy, 0, sizeof(msp->legacy));
932 msp->legacy.r = msp->ratelist;
933 msp->legacy.sample_table = msp->sample_table;
934 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
935 }
936
937 static void
938 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
939 struct ieee80211_sta *sta, void *priv_sta)
940 {
941 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
942 }
943
944 static void
945 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
946 struct ieee80211_sta *sta, void *priv_sta,
947 u32 changed)
948 {
949 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
950 }
951
952 static void *
953 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
954 {
955 struct ieee80211_supported_band *sband;
956 struct minstrel_ht_sta_priv *msp;
957 struct minstrel_priv *mp = priv;
958 struct ieee80211_hw *hw = mp->hw;
959 int max_rates = 0;
960 int i;
961
962 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
963 sband = hw->wiphy->bands[i];
964 if (sband && sband->n_bitrates > max_rates)
965 max_rates = sband->n_bitrates;
966 }
967
968 msp = kzalloc(sizeof(*msp), gfp);
969 if (!msp)
970 return NULL;
971
972 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
973 if (!msp->ratelist)
974 goto error;
975
976 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
977 if (!msp->sample_table)
978 goto error1;
979
980 return msp;
981
982 error1:
983 kfree(msp->ratelist);
984 error:
985 kfree(msp);
986 return NULL;
987 }
988
989 static void
990 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
991 {
992 struct minstrel_ht_sta_priv *msp = priv_sta;
993
994 kfree(msp->sample_table);
995 kfree(msp->ratelist);
996 kfree(msp);
997 }
998
999 static void *
1000 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
1001 {
1002 return mac80211_minstrel.alloc(hw, debugfsdir);
1003 }
1004
1005 static void
1006 minstrel_ht_free(void *priv)
1007 {
1008 mac80211_minstrel.free(priv);
1009 }
1010
1011 static struct rate_control_ops mac80211_minstrel_ht = {
1012 .name = "minstrel_ht",
1013 .tx_status = minstrel_ht_tx_status,
1014 .get_rate = minstrel_ht_get_rate,
1015 .rate_init = minstrel_ht_rate_init,
1016 .rate_update = minstrel_ht_rate_update,
1017 .alloc_sta = minstrel_ht_alloc_sta,
1018 .free_sta = minstrel_ht_free_sta,
1019 .alloc = minstrel_ht_alloc,
1020 .free = minstrel_ht_free,
1021 #ifdef CONFIG_MAC80211_DEBUGFS
1022 .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
1023 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
1024 #endif
1025 };
1026
1027
1028 static void
1029 init_sample_table(void)
1030 {
1031 int col, i, new_idx;
1032 u8 rnd[MCS_GROUP_RATES];
1033
1034 memset(sample_table, 0xff, sizeof(sample_table));
1035 for (col = 0; col < SAMPLE_COLUMNS; col++) {
1036 for (i = 0; i < MCS_GROUP_RATES; i++) {
1037 get_random_bytes(rnd, sizeof(rnd));
1038 new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
1039
1040 while (sample_table[col][new_idx] != 0xff)
1041 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
1042
1043 sample_table[col][new_idx] = i;
1044 }
1045 }
1046 }
1047
1048 int __init
1049 rc80211_minstrel_ht_init(void)
1050 {
1051 init_sample_table();
1052 return ieee80211_rate_control_register(&mac80211_minstrel_ht);
1053 }
1054
1055 void
1056 rc80211_minstrel_ht_exit(void)
1057 {
1058 ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
1059 }
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