2 Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
3 <http://rt2x00.serialmonkey.com>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the
17 Free Software Foundation, Inc.,
18 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
23 Abstract: rt2x00 generic link tuning routines.
26 #include <linux/kernel.h>
27 #include <linux/module.h>
30 #include "rt2x00lib.h"
33 * When we lack RSSI information return something less then -80 to
34 * tell the driver to tune the device to maximum sensitivity.
36 #define DEFAULT_RSSI -128
39 * When no TX/RX percentage could be calculated due to lack of
40 * frames on the air, we fallback to a percentage of 50%.
41 * This will assure we will get at least get some decent value
42 * when the link tuner starts.
43 * The value will be dropped and overwritten with the correct (measured)
44 * value anyway during the first run of the link tuner.
46 #define DEFAULT_PERCENTAGE 50
49 * Small helper macro to work with moving/walking averages.
50 * When adding a value to the average value the following calculation
53 * avg_rssi = ((avg_rssi * 7) + rssi) / 8;
55 * The advantage of this approach is that we only need 1 variable
56 * to store the average in (No need for a count and a total).
57 * But more importantly, normal average values will over time
58 * move less and less towards newly added values this results
59 * that with link tuning, the device can have a very good RSSI
60 * for a few minutes but when the device is moved away from the AP
61 * the average will not decrease fast enough to compensate.
62 * The walking average compensates this and will move towards
63 * the new values correctly allowing a effective link tuning.
65 #define MOVING_AVERAGE(__avg, __val, __samples) \
66 ( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )
69 * Small helper macro for percentage calculation
70 * This is a very simple macro with the only catch that it will
71 * produce a default value in case no total value was provided.
73 #define PERCENTAGE(__value, __total) \
74 ( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )
77 * For calculating the Signal quality we have determined
78 * the total number of success and failed RX and TX frames.
79 * With the addition of the average RSSI value we can determine
80 * the link quality using the following algorithm:
82 * rssi_percentage = (avg_rssi * 100) / rssi_offset
83 * rx_percentage = (rx_success * 100) / rx_total
84 * tx_percentage = (tx_success * 100) / tx_total
85 * avg_signal = ((WEIGHT_RSSI * avg_rssi) +
86 * (WEIGHT_TX * tx_percentage) +
87 * (WEIGHT_RX * rx_percentage)) / 100
89 * This value should then be checked to not be greater then 100.
90 * This means the values of WEIGHT_RSSI, WEIGHT_RX, WEIGHT_TX must
91 * sum up to 100 as well.
93 #define WEIGHT_RSSI 20
97 static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
99 struct link_ant *ant = &rt2x00dev->link.ant;
101 if (ant->rssi_ant && rt2x00dev->link.qual.rx_success)
102 return ant->rssi_ant;
106 static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev,
107 enum antenna antenna)
109 struct link_ant *ant = &rt2x00dev->link.ant;
111 if (ant->rssi_history[antenna - ANTENNA_A])
112 return ant->rssi_history[antenna - ANTENNA_A];
115 /* Small wrapper for rt2x00link_antenna_get_rssi_history() */
116 #define rt2x00link_antenna_get_rssi_rx_history(__dev) \
117 rt2x00link_antenna_get_rssi_history((__dev), \
118 (__dev)->link.ant.active.rx)
119 #define rt2x00link_antenna_get_rssi_tx_history(__dev) \
120 rt2x00link_antenna_get_rssi_history((__dev), \
121 (__dev)->link.ant.active.tx)
123 static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
124 enum antenna antenna,
127 struct link_ant *ant = &rt2x00dev->link.ant;
128 ant->rssi_history[ant->active.rx - ANTENNA_A] = rssi;
130 /* Small wrapper for rt2x00link_antenna_get_rssi_history() */
131 #define rt2x00link_antenna_update_rssi_rx_history(__dev, __rssi) \
132 rt2x00link_antenna_update_rssi_history((__dev), \
133 (__dev)->link.ant.active.rx, \
135 #define rt2x00link_antenna_update_rssi_tx_history(__dev, __rssi) \
136 rt2x00link_antenna_update_rssi_history((__dev), \
137 (__dev)->link.ant.active.tx, \
140 static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
142 rt2x00dev->link.ant.rssi_ant = 0;
145 static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
147 struct link_ant *ant = &rt2x00dev->link.ant;
148 struct antenna_setup new_ant;
149 int sample_a = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_A);
150 int sample_b = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_B);
152 memcpy(&new_ant, &ant->active, sizeof(new_ant));
155 * We are done sampling. Now we should evaluate the results.
157 ant->flags &= ~ANTENNA_MODE_SAMPLE;
160 * During the last period we have sampled the RSSI
161 * from both antennas. It now is time to determine
162 * which antenna demonstrated the best performance.
163 * When we are already on the antenna with the best
164 * performance, then there really is nothing for us
167 if (sample_a == sample_b)
170 if (ant->flags & ANTENNA_RX_DIVERSITY)
171 new_ant.rx = (sample_a > sample_b) ? ANTENNA_A : ANTENNA_B;
173 if (ant->flags & ANTENNA_TX_DIVERSITY)
174 new_ant.tx = (sample_a > sample_b) ? ANTENNA_A : ANTENNA_B;
176 rt2x00lib_config_antenna(rt2x00dev, new_ant);
179 static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
181 struct link_ant *ant = &rt2x00dev->link.ant;
182 struct antenna_setup new_ant;
186 memcpy(&new_ant, &ant->active, sizeof(new_ant));
189 * Get current RSSI value along with the historical value,
190 * after that update the history with the current value.
192 rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
193 rssi_old = rt2x00link_antenna_get_rssi_rx_history(rt2x00dev);
194 rt2x00link_antenna_update_rssi_rx_history(rt2x00dev, rssi_curr);
197 * Legacy driver indicates that we should swap antenna's
198 * when the difference in RSSI is greater that 5. This
199 * also should be done when the RSSI was actually better
200 * then the previous sample.
201 * When the difference exceeds the threshold we should
202 * sample the rssi from the other antenna to make a valid
203 * comparison between the 2 antennas.
205 if (abs(rssi_curr - rssi_old) < 5)
208 ant->flags |= ANTENNA_MODE_SAMPLE;
210 if (ant->flags & ANTENNA_RX_DIVERSITY)
211 new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
213 if (ant->flags & ANTENNA_TX_DIVERSITY)
214 new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
216 rt2x00lib_config_antenna(rt2x00dev, new_ant);
219 static void rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
221 struct link_ant *ant = &rt2x00dev->link.ant;
222 unsigned int flags = ant->flags;
225 * Determine if software diversity is enabled for
226 * either the TX or RX antenna (or both).
227 * Always perform this check since within the link
228 * tuner interval the configuration might have changed.
230 flags &= ~ANTENNA_RX_DIVERSITY;
231 flags &= ~ANTENNA_TX_DIVERSITY;
233 if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
234 flags |= ANTENNA_RX_DIVERSITY;
235 if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
236 flags |= ANTENNA_TX_DIVERSITY;
238 if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
239 !(ant->flags & ANTENNA_TX_DIVERSITY)) {
248 * If we have only sampled the data over the last period
249 * we should now harvest the data. Otherwise just evaluate
250 * the data. The latter should only be performed once
253 if (ant->flags & ANTENNA_MODE_SAMPLE)
254 rt2x00lib_antenna_diversity_sample(rt2x00dev);
255 else if (rt2x00dev->link.count & 1)
256 rt2x00lib_antenna_diversity_eval(rt2x00dev);
259 void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
261 struct rxdone_entry_desc *rxdesc)
263 struct link *link = &rt2x00dev->link;
264 struct link_qual *qual = &rt2x00dev->link.qual;
265 struct link_ant *ant = &rt2x00dev->link.ant;
266 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
267 int avg_rssi = rxdesc->rssi;
268 int ant_rssi = rxdesc->rssi;
271 * Frame was received successfully since non-succesfull
272 * frames would have been dropped by the hardware.
277 * We are only interested in quality statistics from
278 * beacons which came from the BSS which we are
281 if (!ieee80211_is_beacon(hdr->frame_control) ||
282 !(rxdesc->dev_flags & RXDONE_MY_BSS))
289 avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
290 link->avg_rssi = avg_rssi;
293 * Update antenna RSSI
296 ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
297 ant->rssi_ant = ant_rssi;
300 static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
302 struct link *link = &rt2x00dev->link;
303 struct link_qual *qual = &rt2x00dev->link.qual;
305 link->rx_percentage =
306 PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
307 link->tx_percentage =
308 PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
311 int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
313 struct link *link = &rt2x00dev->link;
314 int rssi_percentage = 0;
318 * We need a positive value for the RSSI.
321 rssi += rt2x00dev->rssi_offset;
324 * Calculate the different percentages,
325 * which will be used for the signal.
327 rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);
330 * Add the individual percentages and use the WEIGHT
331 * defines to calculate the current link signal.
333 signal = ((WEIGHT_RSSI * rssi_percentage) +
334 (WEIGHT_TX * link->tx_percentage) +
335 (WEIGHT_RX * link->rx_percentage)) / 100;
337 return max_t(int, signal, 100);
340 void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
342 struct link *link = &rt2x00dev->link;
345 * Link tuning should only be performed when
346 * an active sta or master interface exists.
347 * Single monitor mode interfaces should never have
348 * work with link tuners.
350 if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
353 link->rx_percentage = DEFAULT_PERCENTAGE;
354 link->tx_percentage = DEFAULT_PERCENTAGE;
356 rt2x00link_reset_tuner(rt2x00dev, false);
358 ieee80211_queue_delayed_work(rt2x00dev->hw,
359 &link->work, LINK_TUNE_INTERVAL);
362 void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
364 cancel_delayed_work_sync(&rt2x00dev->link.work);
367 void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
369 struct link_qual *qual = &rt2x00dev->link.qual;
371 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
375 * Reset link information.
376 * Both the currently active vgc level as well as
377 * the link tuner counter should be reset. Resetting
378 * the counter is important for devices where the
379 * device should only perform link tuning during the
380 * first minute after being enabled.
382 rt2x00dev->link.count = 0;
383 memset(qual, 0, sizeof(*qual));
386 * Reset the link tuner.
388 rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
391 rt2x00link_antenna_reset(rt2x00dev);
394 static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
396 struct link_qual *qual = &rt2x00dev->link.qual;
398 qual->rx_success = 0;
400 qual->tx_success = 0;
404 static void rt2x00link_tuner(struct work_struct *work)
406 struct rt2x00_dev *rt2x00dev =
407 container_of(work, struct rt2x00_dev, link.work.work);
408 struct link *link = &rt2x00dev->link;
409 struct link_qual *qual = &rt2x00dev->link.qual;
412 * When the radio is shutting down we should
413 * immediately cease all link tuning.
415 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
421 rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
422 rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
425 * Update quality RSSI for link tuning,
426 * when we have received some frames and we managed to
427 * collect the RSSI data we could use this. Otherwise we
428 * must fallback to the default RSSI value.
430 if (!link->avg_rssi || !qual->rx_success)
431 qual->rssi = DEFAULT_RSSI;
433 qual->rssi = link->avg_rssi;
436 * Only perform the link tuning when Link tuning
437 * has been enabled (This could have been disabled from the EEPROM).
439 if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
440 rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
443 * Precalculate a portion of the link signal which is
444 * in based on the tx/rx success/failure counters.
446 rt2x00link_precalculate_signal(rt2x00dev);
449 * Send a signal to the led to update the led signal strength.
451 rt2x00leds_led_quality(rt2x00dev, link->avg_rssi);
454 * Evaluate antenna setup, make this the last step since this could
455 * possibly reset some statistics.
457 rt2x00lib_antenna_diversity(rt2x00dev);
460 * Reset the quality counters which recounted during each period.
462 rt2x00link_reset_qual(rt2x00dev);
465 * Increase tuner counter, and reschedule the next link tuner run.
468 ieee80211_queue_delayed_work(rt2x00dev->hw,
469 &link->work, LINK_TUNE_INTERVAL);
472 void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
474 INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);