rate.c revision 234e340582901211f40d8c732afc49f0630ecf05 
1/*
2 * Copyright 2002-2005, Instant802 Networks, Inc.
3 * Copyright 2005-2006, Devicescape Software, Inc.
4 * Copyright (c) 2006 Jiri Benc <jbenc@suse.cz>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/kernel.h>
12#include <linux/rtnetlink.h>
13#include <linux/slab.h>
14#include <linux/module.h>
15#include "rate.h"
16#include "ieee80211_i.h"
17#include "debugfs.h"
18
19struct rate_control_alg {
20	struct list_head list;
21	struct rate_control_ops *ops;
22};
23
24static LIST_HEAD(rate_ctrl_algs);
25static DEFINE_MUTEX(rate_ctrl_mutex);
26
27static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
28module_param(ieee80211_default_rc_algo, charp, 0644);
29MODULE_PARM_DESC(ieee80211_default_rc_algo,
30		 "Default rate control algorithm for mac80211 to use");
31
32int ieee80211_rate_control_register(struct rate_control_ops *ops)
33{
34	struct rate_control_alg *alg;
35
36	if (!ops->name)
37		return -EINVAL;
38
39	mutex_lock(&rate_ctrl_mutex);
40	list_for_each_entry(alg, &rate_ctrl_algs, list) {
41		if (!strcmp(alg->ops->name, ops->name)) {
42			/* don't register an algorithm twice */
43			WARN_ON(1);
44			mutex_unlock(&rate_ctrl_mutex);
45			return -EALREADY;
46		}
47	}
48
49	alg = kzalloc(sizeof(*alg), GFP_KERNEL);
50	if (alg == NULL) {
51		mutex_unlock(&rate_ctrl_mutex);
52		return -ENOMEM;
53	}
54	alg->ops = ops;
55
56	list_add_tail(&alg->list, &rate_ctrl_algs);
57	mutex_unlock(&rate_ctrl_mutex);
58
59	return 0;
60}
61EXPORT_SYMBOL(ieee80211_rate_control_register);
62
63void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
64{
65	struct rate_control_alg *alg;
66
67	mutex_lock(&rate_ctrl_mutex);
68	list_for_each_entry(alg, &rate_ctrl_algs, list) {
69		if (alg->ops == ops) {
70			list_del(&alg->list);
71			kfree(alg);
72			break;
73		}
74	}
75	mutex_unlock(&rate_ctrl_mutex);
76}
77EXPORT_SYMBOL(ieee80211_rate_control_unregister);
78
79static struct rate_control_ops *
80ieee80211_try_rate_control_ops_get(const char *name)
81{
82	struct rate_control_alg *alg;
83	struct rate_control_ops *ops = NULL;
84
85	if (!name)
86		return NULL;
87
88	mutex_lock(&rate_ctrl_mutex);
89	list_for_each_entry(alg, &rate_ctrl_algs, list) {
90		if (!strcmp(alg->ops->name, name))
91			if (try_module_get(alg->ops->module)) {
92				ops = alg->ops;
93				break;
94			}
95	}
96	mutex_unlock(&rate_ctrl_mutex);
97	return ops;
98}
99
100/* Get the rate control algorithm. */
101static struct rate_control_ops *
102ieee80211_rate_control_ops_get(const char *name)
103{
104	struct rate_control_ops *ops;
105	const char *alg_name;
106
107	kparam_block_sysfs_write(ieee80211_default_rc_algo);
108	if (!name)
109		alg_name = ieee80211_default_rc_algo;
110	else
111		alg_name = name;
112
113	ops = ieee80211_try_rate_control_ops_get(alg_name);
114	if (!ops) {
115		request_module("rc80211_%s", alg_name);
116		ops = ieee80211_try_rate_control_ops_get(alg_name);
117	}
118	if (!ops && name)
119		/* try default if specific alg requested but not found */
120		ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
121
122	/* try built-in one if specific alg requested but not found */
123	if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
124		ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
125	kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
126
127	return ops;
128}
129
130static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
131{
132	module_put(ops->module);
133}
134
135#ifdef CONFIG_MAC80211_DEBUGFS
136static ssize_t rcname_read(struct file *file, char __user *userbuf,
137			   size_t count, loff_t *ppos)
138{
139	struct rate_control_ref *ref = file->private_data;
140	int len = strlen(ref->ops->name);
141
142	return simple_read_from_buffer(userbuf, count, ppos,
143				       ref->ops->name, len);
144}
145
146static const struct file_operations rcname_ops = {
147	.read = rcname_read,
148	.open = simple_open,
149	.llseek = default_llseek,
150};
151#endif
152
153static struct rate_control_ref *rate_control_alloc(const char *name,
154					    struct ieee80211_local *local)
155{
156	struct dentry *debugfsdir = NULL;
157	struct rate_control_ref *ref;
158
159	ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
160	if (!ref)
161		goto fail_ref;
162	ref->local = local;
163	ref->ops = ieee80211_rate_control_ops_get(name);
164	if (!ref->ops)
165		goto fail_ops;
166
167#ifdef CONFIG_MAC80211_DEBUGFS
168	debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
169	local->debugfs.rcdir = debugfsdir;
170	debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
171#endif
172
173	ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
174	if (!ref->priv)
175		goto fail_priv;
176	return ref;
177
178fail_priv:
179	ieee80211_rate_control_ops_put(ref->ops);
180fail_ops:
181	kfree(ref);
182fail_ref:
183	return NULL;
184}
185
186static void rate_control_free(struct rate_control_ref *ctrl_ref)
187{
188	ctrl_ref->ops->free(ctrl_ref->priv);
189
190#ifdef CONFIG_MAC80211_DEBUGFS
191	debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
192	ctrl_ref->local->debugfs.rcdir = NULL;
193#endif
194
195	ieee80211_rate_control_ops_put(ctrl_ref->ops);
196	kfree(ctrl_ref);
197}
198
199static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
200{
201	struct sk_buff *skb = txrc->skb;
202	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
203	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
204	__le16 fc;
205
206	fc = hdr->frame_control;
207
208	return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
209			       IEEE80211_TX_CTL_USE_MINRATE)) ||
210		!ieee80211_is_data(fc);
211}
212
213static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
214				  struct ieee80211_supported_band *sband)
215{
216	u8 i;
217
218	if (basic_rates == 0)
219		return; /* assume basic rates unknown and accept rate */
220	if (*idx < 0)
221		return;
222	if (basic_rates & (1 << *idx))
223		return; /* selected rate is a basic rate */
224
225	for (i = *idx + 1; i <= sband->n_bitrates; i++) {
226		if (basic_rates & (1 << i)) {
227			*idx = i;
228			return;
229		}
230	}
231
232	/* could not find a basic rate; use original selection */
233}
234
235static inline s8
236rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
237			  struct ieee80211_sta *sta)
238{
239	int i;
240
241	for (i = 0; i < sband->n_bitrates; i++) {
242		struct ieee80211_rate *srate = &sband->bitrates[i];
243		if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
244		    (srate->bitrate == 55) || (srate->bitrate == 110))
245			continue;
246
247		if (rate_supported(sta, sband->band, i))
248			return i;
249	}
250
251	/* No matching rate found */
252	return 0;
253}
254
255
256bool rate_control_send_low(struct ieee80211_sta *sta,
257			   void *priv_sta,
258			   struct ieee80211_tx_rate_control *txrc)
259{
260	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
261	struct ieee80211_supported_band *sband = txrc->sband;
262	int mcast_rate;
263
264	if (!sta || !priv_sta || rc_no_data_or_no_ack_use_min(txrc)) {
265		if ((sband->band != IEEE80211_BAND_2GHZ) ||
266		    !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
267			info->control.rates[0].idx =
268				rate_lowest_index(txrc->sband, sta);
269		else
270			info->control.rates[0].idx =
271				rate_lowest_non_cck_index(txrc->sband, sta);
272		info->control.rates[0].count =
273			(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
274			1 : txrc->hw->max_rate_tries;
275		if (!sta && txrc->bss) {
276			mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
277			if (mcast_rate > 0) {
278				info->control.rates[0].idx = mcast_rate - 1;
279				return true;
280			}
281
282			rc_send_low_broadcast(&info->control.rates[0].idx,
283					      txrc->bss_conf->basic_rates,
284					      sband);
285		}
286		return true;
287	}
288	return false;
289}
290EXPORT_SYMBOL(rate_control_send_low);
291
292static bool rate_idx_match_legacy_mask(struct ieee80211_tx_rate *rate,
293				       int n_bitrates, u32 mask)
294{
295	int j;
296
297	/* See whether the selected rate or anything below it is allowed. */
298	for (j = rate->idx; j >= 0; j--) {
299		if (mask & (1 << j)) {
300			/* Okay, found a suitable rate. Use it. */
301			rate->idx = j;
302			return true;
303		}
304	}
305
306	/* Try to find a higher rate that would be allowed */
307	for (j = rate->idx + 1; j < n_bitrates; j++) {
308		if (mask & (1 << j)) {
309			/* Okay, found a suitable rate. Use it. */
310			rate->idx = j;
311			return true;
312		}
313	}
314	return false;
315}
316
317static bool rate_idx_match_mcs_mask(struct ieee80211_tx_rate *rate,
318				    u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
319{
320	int i, j;
321	int ridx, rbit;
322
323	ridx = rate->idx / 8;
324	rbit = rate->idx % 8;
325
326	/* sanity check */
327	if (ridx < 0 || ridx >= IEEE80211_HT_MCS_MASK_LEN)
328		return false;
329
330	/* See whether the selected rate or anything below it is allowed. */
331	for (i = ridx; i >= 0; i--) {
332		for (j = rbit; j >= 0; j--)
333			if (mcs_mask[i] & BIT(j)) {
334				rate->idx = i * 8 + j;
335				return true;
336			}
337		rbit = 7;
338	}
339
340	/* Try to find a higher rate that would be allowed */
341	ridx = (rate->idx + 1) / 8;
342	rbit = (rate->idx + 1) % 8;
343
344	for (i = ridx; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
345		for (j = rbit; j < 8; j++)
346			if (mcs_mask[i] & BIT(j)) {
347				rate->idx = i * 8 + j;
348				return true;
349			}
350		rbit = 0;
351	}
352	return false;
353}
354
355
356
357static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
358				struct ieee80211_tx_rate_control *txrc,
359				u32 mask,
360				u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
361{
362	struct ieee80211_tx_rate alt_rate;
363
364	/* handle HT rates */
365	if (rate->flags & IEEE80211_TX_RC_MCS) {
366		if (rate_idx_match_mcs_mask(rate, mcs_mask))
367			return;
368
369		/* also try the legacy rates. */
370		alt_rate.idx = 0;
371		/* keep protection flags */
372		alt_rate.flags = rate->flags &
373				 (IEEE80211_TX_RC_USE_RTS_CTS |
374				  IEEE80211_TX_RC_USE_CTS_PROTECT |
375				  IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
376		alt_rate.count = rate->count;
377		if (rate_idx_match_legacy_mask(&alt_rate,
378					       txrc->sband->n_bitrates,
379					       mask)) {
380			*rate = alt_rate;
381			return;
382		}
383	} else {
384		struct sk_buff *skb = txrc->skb;
385		struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
386		__le16 fc;
387
388		/* handle legacy rates */
389		if (rate_idx_match_legacy_mask(rate, txrc->sband->n_bitrates,
390					       mask))
391			return;
392
393		/* if HT BSS, and we handle a data frame, also try HT rates */
394		if (txrc->bss_conf->channel_type == NL80211_CHAN_NO_HT)
395			return;
396
397		fc = hdr->frame_control;
398		if (!ieee80211_is_data(fc))
399			return;
400
401		alt_rate.idx = 0;
402		/* keep protection flags */
403		alt_rate.flags = rate->flags &
404				 (IEEE80211_TX_RC_USE_RTS_CTS |
405				  IEEE80211_TX_RC_USE_CTS_PROTECT |
406				  IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
407		alt_rate.count = rate->count;
408
409		alt_rate.flags |= IEEE80211_TX_RC_MCS;
410
411		if ((txrc->bss_conf->channel_type == NL80211_CHAN_HT40MINUS) ||
412		    (txrc->bss_conf->channel_type == NL80211_CHAN_HT40PLUS))
413			alt_rate.flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
414
415		if (rate_idx_match_mcs_mask(&alt_rate, mcs_mask)) {
416			*rate = alt_rate;
417			return;
418		}
419	}
420
421	/*
422	 * Uh.. No suitable rate exists. This should not really happen with
423	 * sane TX rate mask configurations. However, should someone manage to
424	 * configure supported rates and TX rate mask in incompatible way,
425	 * allow the frame to be transmitted with whatever the rate control
426	 * selected.
427	 */
428}
429
430void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
431			   struct sta_info *sta,
432			   struct ieee80211_tx_rate_control *txrc)
433{
434	struct rate_control_ref *ref = sdata->local->rate_ctrl;
435	void *priv_sta = NULL;
436	struct ieee80211_sta *ista = NULL;
437	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
438	int i;
439	u32 mask;
440	u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
441
442	if (sta && test_sta_flag(sta, WLAN_STA_RATE_CONTROL)) {
443		ista = &sta->sta;
444		priv_sta = sta->rate_ctrl_priv;
445	}
446
447	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
448		info->control.rates[i].idx = -1;
449		info->control.rates[i].flags = 0;
450		info->control.rates[i].count = 0;
451	}
452
453	if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
454		return;
455
456	ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
457
458	/*
459	 * Try to enforce the rateidx mask the user wanted. skip this if the
460	 * default mask (allow all rates) is used to save some processing for
461	 * the common case.
462	 */
463	mask = sdata->rc_rateidx_mask[info->band];
464	memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[info->band],
465	       sizeof(mcs_mask));
466	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
467		if (sta) {
468			/* Filter out rates that the STA does not support */
469			mask &= sta->sta.supp_rates[info->band];
470			for (i = 0; i < sizeof(mcs_mask); i++)
471				mcs_mask[i] &= sta->sta.ht_cap.mcs.rx_mask[i];
472		}
473		/*
474		 * Make sure the rate index selected for each TX rate is
475		 * included in the configured mask and change the rate indexes
476		 * if needed.
477		 */
478		for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
479			/* Skip invalid rates */
480			if (info->control.rates[i].idx < 0)
481				break;
482			rate_idx_match_mask(&info->control.rates[i], txrc,
483					    mask, mcs_mask);
484		}
485	}
486
487	BUG_ON(info->control.rates[0].idx < 0);
488}
489
490int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
491				 const char *name)
492{
493	struct rate_control_ref *ref;
494
495	ASSERT_RTNL();
496
497	if (local->open_count)
498		return -EBUSY;
499
500	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
501		if (WARN_ON(!local->ops->set_rts_threshold))
502			return -EINVAL;
503		return 0;
504	}
505
506	ref = rate_control_alloc(name, local);
507	if (!ref) {
508		wiphy_warn(local->hw.wiphy,
509			   "Failed to select rate control algorithm\n");
510		return -ENOENT;
511	}
512
513	WARN_ON(local->rate_ctrl);
514	local->rate_ctrl = ref;
515
516	wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
517		    ref->ops->name);
518
519	return 0;
520}
521
522void rate_control_deinitialize(struct ieee80211_local *local)
523{
524	struct rate_control_ref *ref;
525
526	ref = local->rate_ctrl;
527
528	if (!ref)
529		return;
530
531	local->rate_ctrl = NULL;
532	rate_control_free(ref);
533}
534
535