summaryrefslogtreecommitdiffstats
path: root/drivers/net/wireless/rt2x00/rt2x00link.c
blob: eb9b981b9139f2ff976a47095a2a7202d8ab2aa5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
/*
	Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
	<http://rt2x00.serialmonkey.com>

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the
	Free Software Foundation, Inc.,
	59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*
	Module: rt2x00lib
	Abstract: rt2x00 generic link tuning routines.
 */

#include <linux/kernel.h>
#include <linux/module.h>

#include "rt2x00.h"
#include "rt2x00lib.h"

/*
 * When we lack RSSI information return something less then -80 to
 * tell the driver to tune the device to maximum sensitivity.
 */
#define DEFAULT_RSSI		-128

/*
 * When no TX/RX percentage could be calculated due to lack of
 * frames on the air, we fallback to a percentage of 50%.
 * This will assure we will get at least get some decent value
 * when the link tuner starts.
 * The value will be dropped and overwritten with the correct (measured)
 * value anyway during the first run of the link tuner.
 */
#define DEFAULT_PERCENTAGE	50

/*
 * Small helper macro to work with moving/walking averages.
 * When adding a value to the average value the following calculation
 * is needed:
 *
 *        avg_rssi = ((avg_rssi * 7) + rssi) / 8;
 *
 * The advantage of this approach is that we only need 1 variable
 * to store the average in (No need for a count and a total).
 * But more importantly, normal average values will over time
 * move less and less towards newly added values this results
 * that with link tuning, the device can have a very good RSSI
 * for a few minutes but when the device is moved away from the AP
 * the average will not decrease fast enough to compensate.
 * The walking average compensates this and will move towards
 * the new values correctly allowing a effective link tuning.
 */
#define MOVING_AVERAGE(__avg, __val, __samples) \
	( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )

/*
 * Small helper macro for percentage calculation
 * This is a very simple macro with the only catch that it will
 * produce a default value in case no total value was provided.
 */
#define PERCENTAGE(__value, __total) \
	( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )

/*
 * For calculating the Signal quality we have determined
 * the total number of success and failed RX and TX frames.
 * With the addition of the average RSSI value we can determine
 * the link quality using the following algorithm:
 *
 *         rssi_percentage = (avg_rssi * 100) / rssi_offset
 *         rx_percentage = (rx_success * 100) / rx_total
 *         tx_percentage = (tx_success * 100) / tx_total
 *         avg_signal = ((WEIGHT_RSSI * avg_rssi) +
 *                       (WEIGHT_TX * tx_percentage) +
 *                       (WEIGHT_RX * rx_percentage)) / 100
 *
 * This value should then be checked to not be greater then 100.
 * This means the values of WEIGHT_RSSI, WEIGHT_RX, WEIGHT_TX must
 * sum up to 100 as well.
 */
#define WEIGHT_RSSI	20
#define WEIGHT_RX	40
#define WEIGHT_TX	40

static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
{
	struct link_ant *ant = &rt2x00dev->link.ant;

	if (ant->rssi_ant && rt2x00dev->link.qual.rx_success)
		return ant->rssi_ant;
	return DEFAULT_RSSI;
}

static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev,
					       enum antenna antenna)
{
	struct link_ant *ant = &rt2x00dev->link.ant;

	if (ant->rssi_history[antenna - ANTENNA_A])
		return ant->rssi_history[antenna - ANTENNA_A];
	return DEFAULT_RSSI;
}
/* Small wrapper for rt2x00link_antenna_get_rssi_history() */
#define rt2x00link_antenna_get_rssi_rx_history(__dev) \
	rt2x00link_antenna_get_rssi_history((__dev), \
					    (__dev)->link.ant.active.rx)
#define rt2x00link_antenna_get_rssi_tx_history(__dev) \
	rt2x00link_antenna_get_rssi_history((__dev), \
					    (__dev)->link.ant.active.tx)

static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
						   enum antenna antenna,
						   int rssi)
{
	struct link_ant *ant = &rt2x00dev->link.ant;
	ant->rssi_history[ant->active.rx - ANTENNA_A] = rssi;
}
/* Small wrapper for rt2x00link_antenna_get_rssi_history() */
#define rt2x00link_antenna_update_rssi_rx_history(__dev, __rssi) \
	rt2x00link_antenna_update_rssi_history((__dev), \
					       (__dev)->link.ant.active.rx, \
					       (__rssi))
#define rt2x00link_antenna_update_rssi_tx_history(__dev, __rssi) \
	rt2x00link_antenna_update_rssi_history((__dev), \
					       (__dev)->link.ant.active.tx, \
					       (__rssi))

static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
{
	rt2x00dev->link.ant.rssi_ant = 0;
}

static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
{
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct antenna_setup new_ant;
	int sample_a = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_A);
	int sample_b = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_B);

	memcpy(&new_ant, &ant->active, sizeof(new_ant));

	/*
	 * We are done sampling. Now we should evaluate the results.
	 */
	ant->flags &= ~ANTENNA_MODE_SAMPLE;

	/*
	 * During the last period we have sampled the RSSI
	 * from both antenna's. It now is time to determine
	 * which antenna demonstrated the best performance.
	 * When we are already on the antenna with the best
	 * performance, then there really is nothing for us
	 * left to do.
	 */
	if (sample_a == sample_b)
		return;

	if (ant->flags & ANTENNA_RX_DIVERSITY)
		new_ant.rx = (sample_a > sample_b) ? ANTENNA_A : ANTENNA_B;

	if (ant->flags & ANTENNA_TX_DIVERSITY)
		new_ant.tx = (sample_a > sample_b) ? ANTENNA_A : ANTENNA_B;

	rt2x00lib_config_antenna(rt2x00dev, &new_ant);
}

static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
{
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct antenna_setup new_ant;
	int rssi_curr;
	int rssi_old;

	memcpy(&new_ant, &ant->active, sizeof(new_ant));

	/*
	 * Get current RSSI value along with the historical value,
	 * after that update the history with the current value.
	 */
	rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
	rssi_old = rt2x00link_antenna_get_rssi_rx_history(rt2x00dev);
	rt2x00link_antenna_update_rssi_rx_history(rt2x00dev, rssi_curr);

	/*
	 * Legacy driver indicates that we should swap antenna's
	 * when the difference in RSSI is greater that 5. This
	 * also should be done when the RSSI was actually better
	 * then the previous sample.
	 * When the difference exceeds the threshold we should
	 * sample the rssi from the other antenna to make a valid
	 * comparison between the 2 antennas.
	 */
	if (abs(rssi_curr - rssi_old) < 5)
		return;

	ant->flags |= ANTENNA_MODE_SAMPLE;

	if (ant->flags & ANTENNA_RX_DIVERSITY)
		new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

	if (ant->flags & ANTENNA_TX_DIVERSITY)
		new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

	rt2x00lib_config_antenna(rt2x00dev, &new_ant);
}

static void rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
{
	struct link_ant *ant = &rt2x00dev->link.ant;

	/*
	 * Determine if software diversity is enabled for
	 * either the TX or RX antenna (or both).
	 * Always perform this check since within the link
	 * tuner interval the configuration might have changed.
	 */
	ant->flags &= ~ANTENNA_RX_DIVERSITY;
	ant->flags &= ~ANTENNA_TX_DIVERSITY;

	if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
		ant->flags |= ANTENNA_RX_DIVERSITY;
	if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
		ant->flags |= ANTENNA_TX_DIVERSITY;

	if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
	    !(ant->flags & ANTENNA_TX_DIVERSITY)) {
		ant->flags = 0;
		return;
	}

	/*
	 * If we have only sampled the data over the last period
	 * we should now harvest the data. Otherwise just evaluate
	 * the data. The latter should only be performed once
	 * every 2 seconds.
	 */
	if (ant->flags & ANTENNA_MODE_SAMPLE)
		rt2x00lib_antenna_diversity_sample(rt2x00dev);
	else if (rt2x00dev->link.count & 1)
		rt2x00lib_antenna_diversity_eval(rt2x00dev);
}

void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
			     struct sk_buff *skb,
			     struct rxdone_entry_desc *rxdesc)
{
	struct link *link = &rt2x00dev->link;
	struct link_qual *qual = &rt2x00dev->link.qual;
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	int avg_rssi = rxdesc->rssi;
	int ant_rssi = rxdesc->rssi;

	/*
	 * Frame was received successfully since non-succesfull
	 * frames would have been dropped by the hardware.
	 */
	qual->rx_success++;

	/*
	 * We are only interested in quality statistics from
	 * beacons which came from the BSS which we are
	 * associated with.
	 */
	if (!ieee80211_is_beacon(hdr->frame_control) ||
	    !(rxdesc->dev_flags & RXDONE_MY_BSS))
		return;

	/*
	 * Update global RSSI
	 */
	if (link->avg_rssi)
		avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
	link->avg_rssi = avg_rssi;

	/*
	 * Update antenna RSSI
	 */
	if (ant->rssi_ant)
		ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
	ant->rssi_ant = ant_rssi;
}

static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
{
	struct link *link = &rt2x00dev->link;
	struct link_qual *qual = &rt2x00dev->link.qual;

	link->rx_percentage =
	    PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
	link->tx_percentage =
	    PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
}

int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
{
	struct link *link = &rt2x00dev->link;
	int rssi_percentage = 0;
	int signal;

	/*
	 * We need a positive value for the RSSI.
	 */
	if (rssi < 0)
		rssi += rt2x00dev->rssi_offset;

	/*
	 * Calculate the different percentages,
	 * which will be used for the signal.
	 */
	rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);

	/*
	 * Add the individual percentages and use the WEIGHT
	 * defines to calculate the current link signal.
	 */
	signal = ((WEIGHT_RSSI * rssi_percentage) +
		  (WEIGHT_TX * link->tx_percentage) +
		  (WEIGHT_RX * link->rx_percentage)) / 100;

	return max_t(int, signal, 100);
}

void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
{
	struct link *link = &rt2x00dev->link;

	/*
	 * Link tuning should only be performed when
	 * an active sta or master interface exists.
	 * Single monitor mode interfaces should never have
	 * work with link tuners.
	 */
	if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
		return;

	link->rx_percentage = DEFAULT_PERCENTAGE;
	link->tx_percentage = DEFAULT_PERCENTAGE;

	rt2x00link_reset_tuner(rt2x00dev, false);

	queue_delayed_work(rt2x00dev->hw->workqueue,
			   &link->work, LINK_TUNE_INTERVAL);
}

void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
{
	cancel_delayed_work_sync(&rt2x00dev->link.work);
}

void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
{
	struct link_qual *qual = &rt2x00dev->link.qual;

	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
		return;

	/*
	 * Reset link information.
	 * Both the currently active vgc level as well as
	 * the link tuner counter should be reset. Resetting
	 * the counter is important for devices where the
	 * device should only perform link tuning during the
	 * first minute after being enabled.
	 */
	rt2x00dev->link.count = 0;
	memset(qual, 0, sizeof(*qual));

	/*
	 * Reset the link tuner.
	 */
	rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);

	if (antenna)
		rt2x00link_antenna_reset(rt2x00dev);
}

static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
{
	struct link_qual *qual = &rt2x00dev->link.qual;

	qual->rx_success = 0;
	qual->rx_failed = 0;
	qual->tx_success = 0;
	qual->tx_failed = 0;
}

static void rt2x00link_tuner(struct work_struct *work)
{
	struct rt2x00_dev *rt2x00dev =
	    container_of(work, struct rt2x00_dev, link.work.work);
	struct link *link = &rt2x00dev->link;
	struct link_qual *qual = &rt2x00dev->link.qual;

	/*
	 * When the radio is shutting down we should
	 * immediately cease all link tuning.
	 */
	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
		return;

	/*
	 * Update statistics.
	 */
	rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
	rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;

	/*
	 * Update quality RSSI for link tuning,
	 * when we have received some frames and we managed to
	 * collect the RSSI data we could use this. Otherwise we
	 * must fallback to the default RSSI value.
	 */
	if (!link->avg_rssi || !qual->rx_success)
		qual->rssi = DEFAULT_RSSI;
	else
		qual->rssi = link->avg_rssi;

	/*
	 * Only perform the link tuning when Link tuning
	 * has been enabled (This could have been disabled from the EEPROM).
	 */
	if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
		rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);

	/*
	 * Precalculate a portion of the link signal which is
	 * in based on the tx/rx success/failure counters.
	 */
	rt2x00link_precalculate_signal(rt2x00dev);

	/*
	 * Send a signal to the led to update the led signal strength.
	 */
	rt2x00leds_led_quality(rt2x00dev, link->avg_rssi);

	/*
	 * Evaluate antenna setup, make this the last step since this could
	 * possibly reset some statistics.
	 */
	rt2x00lib_antenna_diversity(rt2x00dev);

	/*
	 * Reset the quality counters which recounted during each period.
	 */
	rt2x00link_reset_qual(rt2x00dev);

	/*
	 * Increase tuner counter, and reschedule the next link tuner run.
	 */
	link->count++;
	queue_delayed_work(rt2x00dev->hw->workqueue,
			   &link->work, LINK_TUNE_INTERVAL);
}

void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
{
	INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
}
OpenPOWER on IntegriCloud