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)
108 struct link_ant *ant = &rt2x00dev->link.ant;
110 if (ant->rssi_history)
111 return ant->rssi_history;
115 static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
118 struct link_ant *ant = &rt2x00dev->link.ant;
119 ant->rssi_history = rssi;
122 static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
124 rt2x00dev->link.ant.rssi_ant = 0;
127 static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
129 struct link_ant *ant = &rt2x00dev->link.ant;
130 struct antenna_setup new_ant;
133 int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
134 int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
136 memcpy(&new_ant, &ant->active, sizeof(new_ant));
139 * We are done sampling. Now we should evaluate the results.
141 ant->flags &= ~ANTENNA_MODE_SAMPLE;
144 * During the last period we have sampled the RSSI
145 * from both antennas. It now is time to determine
146 * which antenna demonstrated the best performance.
147 * When we are already on the antenna with the best
148 * performance, just create a good starting point
149 * for the history and we are done.
151 if (sample_current >= sample_other) {
152 rt2x00link_antenna_update_rssi_history(rt2x00dev,
157 other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
159 if (ant->flags & ANTENNA_RX_DIVERSITY)
160 new_ant.rx = other_antenna;
162 if (ant->flags & ANTENNA_TX_DIVERSITY)
163 new_ant.tx = other_antenna;
165 rt2x00lib_config_antenna(rt2x00dev, new_ant);
168 static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
170 struct link_ant *ant = &rt2x00dev->link.ant;
171 struct antenna_setup new_ant;
175 memcpy(&new_ant, &ant->active, sizeof(new_ant));
178 * Get current RSSI value along with the historical value,
179 * after that update the history with the current value.
181 rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
182 rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
183 rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);
186 * Legacy driver indicates that we should swap antenna's
187 * when the difference in RSSI is greater that 5. This
188 * also should be done when the RSSI was actually better
189 * then the previous sample.
190 * When the difference exceeds the threshold we should
191 * sample the rssi from the other antenna to make a valid
192 * comparison between the 2 antennas.
194 if (abs(rssi_curr - rssi_old) < 5)
197 ant->flags |= ANTENNA_MODE_SAMPLE;
199 if (ant->flags & ANTENNA_RX_DIVERSITY)
200 new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
202 if (ant->flags & ANTENNA_TX_DIVERSITY)
203 new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
205 rt2x00lib_config_antenna(rt2x00dev, new_ant);
208 static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
210 struct link_ant *ant = &rt2x00dev->link.ant;
211 unsigned int flags = ant->flags;
214 * Determine if software diversity is enabled for
215 * either the TX or RX antenna (or both).
216 * Always perform this check since within the link
217 * tuner interval the configuration might have changed.
219 flags &= ~ANTENNA_RX_DIVERSITY;
220 flags &= ~ANTENNA_TX_DIVERSITY;
222 if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
223 flags |= ANTENNA_RX_DIVERSITY;
224 if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
225 flags |= ANTENNA_TX_DIVERSITY;
227 if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
228 !(ant->flags & ANTENNA_TX_DIVERSITY)) {
237 * If we have only sampled the data over the last period
238 * we should now harvest the data. Otherwise just evaluate
239 * the data. The latter should only be performed once
242 if (ant->flags & ANTENNA_MODE_SAMPLE) {
243 rt2x00lib_antenna_diversity_sample(rt2x00dev);
245 } else if (rt2x00dev->link.count & 1) {
246 rt2x00lib_antenna_diversity_eval(rt2x00dev);
253 void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
255 struct rxdone_entry_desc *rxdesc)
257 struct link *link = &rt2x00dev->link;
258 struct link_qual *qual = &rt2x00dev->link.qual;
259 struct link_ant *ant = &rt2x00dev->link.ant;
260 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
261 int avg_rssi = rxdesc->rssi;
262 int ant_rssi = rxdesc->rssi;
265 * Frame was received successfully since non-succesfull
266 * frames would have been dropped by the hardware.
271 * We are only interested in quality statistics from
272 * beacons which came from the BSS which we are
275 if (!ieee80211_is_beacon(hdr->frame_control) ||
276 !(rxdesc->dev_flags & RXDONE_MY_BSS))
283 avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
284 link->avg_rssi = avg_rssi;
287 * Update antenna RSSI
290 ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
291 ant->rssi_ant = ant_rssi;
294 static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
296 struct link *link = &rt2x00dev->link;
297 struct link_qual *qual = &rt2x00dev->link.qual;
299 link->rx_percentage =
300 PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
301 link->tx_percentage =
302 PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
305 int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
307 struct link *link = &rt2x00dev->link;
308 int rssi_percentage = 0;
312 * We need a positive value for the RSSI.
315 rssi += rt2x00dev->rssi_offset;
318 * Calculate the different percentages,
319 * which will be used for the signal.
321 rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);
324 * Add the individual percentages and use the WEIGHT
325 * defines to calculate the current link signal.
327 signal = ((WEIGHT_RSSI * rssi_percentage) +
328 (WEIGHT_TX * link->tx_percentage) +
329 (WEIGHT_RX * link->rx_percentage)) / 100;
331 return max_t(int, signal, 100);
334 void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
336 struct link *link = &rt2x00dev->link;
339 * Link tuning should only be performed when
340 * an active sta or master interface exists.
341 * Single monitor mode interfaces should never have
342 * work with link tuners.
344 if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
347 link->rx_percentage = DEFAULT_PERCENTAGE;
348 link->tx_percentage = DEFAULT_PERCENTAGE;
350 rt2x00link_reset_tuner(rt2x00dev, false);
352 ieee80211_queue_delayed_work(rt2x00dev->hw,
353 &link->work, LINK_TUNE_INTERVAL);
356 void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
358 cancel_delayed_work_sync(&rt2x00dev->link.work);
361 void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
363 struct link_qual *qual = &rt2x00dev->link.qual;
365 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
369 * Reset link information.
370 * Both the currently active vgc level as well as
371 * the link tuner counter should be reset. Resetting
372 * the counter is important for devices where the
373 * device should only perform link tuning during the
374 * first minute after being enabled.
376 rt2x00dev->link.count = 0;
377 memset(qual, 0, sizeof(*qual));
380 * Reset the link tuner.
382 rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
385 rt2x00link_antenna_reset(rt2x00dev);
388 static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
390 struct link_qual *qual = &rt2x00dev->link.qual;
392 qual->rx_success = 0;
394 qual->tx_success = 0;
398 static void rt2x00link_tuner(struct work_struct *work)
400 struct rt2x00_dev *rt2x00dev =
401 container_of(work, struct rt2x00_dev, link.work.work);
402 struct link *link = &rt2x00dev->link;
403 struct link_qual *qual = &rt2x00dev->link.qual;
406 * When the radio is shutting down we should
407 * immediately cease all link tuning.
409 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
415 rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
416 rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
419 * Update quality RSSI for link tuning,
420 * when we have received some frames and we managed to
421 * collect the RSSI data we could use this. Otherwise we
422 * must fallback to the default RSSI value.
424 if (!link->avg_rssi || !qual->rx_success)
425 qual->rssi = DEFAULT_RSSI;
427 qual->rssi = link->avg_rssi;
430 * Only perform the link tuning when Link tuning
431 * has been enabled (This could have been disabled from the EEPROM).
433 if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
434 rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
437 * Precalculate a portion of the link signal which is
438 * in based on the tx/rx success/failure counters.
440 rt2x00link_precalculate_signal(rt2x00dev);
443 * Send a signal to the led to update the led signal strength.
445 rt2x00leds_led_quality(rt2x00dev, link->avg_rssi);
448 * Evaluate antenna setup, make this the last step when
449 * rt2x00lib_antenna_diversity made changes the quality
450 * statistics will be reset.
452 if (rt2x00lib_antenna_diversity(rt2x00dev))
453 rt2x00link_reset_qual(rt2x00dev);
456 * Increase tuner counter, and reschedule the next link tuner run.
459 ieee80211_queue_delayed_work(rt2x00dev->hw,
460 &link->work, LINK_TUNE_INTERVAL);
463 void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
465 INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);