2 Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
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 * Helper struct and macro to work with moving/walking averages.
40 * When adding a value to the average value the following calculation
43 * avg_rssi = ((avg_rssi * 7) + rssi) / 8;
45 * The advantage of this approach is that we only need 1 variable
46 * to store the average in (No need for a count and a total).
47 * But more importantly, normal average values will over time
48 * move less and less towards newly added values this results
49 * that with link tuning, the device can have a very good RSSI
50 * for a few minutes but when the device is moved away from the AP
51 * the average will not decrease fast enough to compensate.
52 * The walking average compensates this and will move towards
53 * the new values correctly allowing a effective link tuning,
54 * the speed of the average moving towards other values depends
55 * on the value for the number of samples. The higher the number
56 * of samples, the slower the average will move.
57 * We use two variables to keep track of the average value to
58 * compensate for the rounding errors. This can be a significant
59 * error (>5dBm) if the factor is too low.
62 #define AVG_FACTOR 1000
63 #define MOVING_AVERAGE(__avg, __val) \
65 struct avg_val __new; \
67 (__avg).avg_weight ? \
68 ((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \
69 ((__val) * (AVG_FACTOR))) / \
71 ((__val) * (AVG_FACTOR)); \
72 __new.avg = __new.avg_weight / (AVG_FACTOR); \
76 static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
78 struct link_ant *ant = &rt2x00dev->link.ant;
80 if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)
81 return ant->rssi_ant.avg;
85 static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
87 struct link_ant *ant = &rt2x00dev->link.ant;
89 if (ant->rssi_history)
90 return ant->rssi_history;
94 static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
97 struct link_ant *ant = &rt2x00dev->link.ant;
98 ant->rssi_history = rssi;
101 static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
103 rt2x00dev->link.ant.rssi_ant.avg = 0;
104 rt2x00dev->link.ant.rssi_ant.avg_weight = 0;
107 static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
109 struct link_ant *ant = &rt2x00dev->link.ant;
110 struct antenna_setup new_ant;
113 int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
114 int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
116 memcpy(&new_ant, &ant->active, sizeof(new_ant));
119 * We are done sampling. Now we should evaluate the results.
121 ant->flags &= ~ANTENNA_MODE_SAMPLE;
124 * During the last period we have sampled the RSSI
125 * from both antennas. It now is time to determine
126 * which antenna demonstrated the best performance.
127 * When we are already on the antenna with the best
128 * performance, just create a good starting point
129 * for the history and we are done.
131 if (sample_current >= sample_other) {
132 rt2x00link_antenna_update_rssi_history(rt2x00dev,
137 other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
139 if (ant->flags & ANTENNA_RX_DIVERSITY)
140 new_ant.rx = other_antenna;
142 if (ant->flags & ANTENNA_TX_DIVERSITY)
143 new_ant.tx = other_antenna;
145 rt2x00lib_config_antenna(rt2x00dev, new_ant);
148 static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
150 struct link_ant *ant = &rt2x00dev->link.ant;
151 struct antenna_setup new_ant;
155 memcpy(&new_ant, &ant->active, sizeof(new_ant));
158 * Get current RSSI value along with the historical value,
159 * after that update the history with the current value.
161 rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
162 rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
163 rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);
166 * Legacy driver indicates that we should swap antenna's
167 * when the difference in RSSI is greater that 5. This
168 * also should be done when the RSSI was actually better
169 * then the previous sample.
170 * When the difference exceeds the threshold we should
171 * sample the rssi from the other antenna to make a valid
172 * comparison between the 2 antennas.
174 if (abs(rssi_curr - rssi_old) < 5)
177 ant->flags |= ANTENNA_MODE_SAMPLE;
179 if (ant->flags & ANTENNA_RX_DIVERSITY)
180 new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
182 if (ant->flags & ANTENNA_TX_DIVERSITY)
183 new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
185 rt2x00lib_config_antenna(rt2x00dev, new_ant);
188 static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
190 struct link_ant *ant = &rt2x00dev->link.ant;
191 unsigned int flags = ant->flags;
194 * Determine if software diversity is enabled for
195 * either the TX or RX antenna (or both).
196 * Always perform this check since within the link
197 * tuner interval the configuration might have changed.
199 flags &= ~ANTENNA_RX_DIVERSITY;
200 flags &= ~ANTENNA_TX_DIVERSITY;
202 if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
203 flags |= ANTENNA_RX_DIVERSITY;
204 if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
205 flags |= ANTENNA_TX_DIVERSITY;
207 if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
208 !(ant->flags & ANTENNA_TX_DIVERSITY)) {
217 * If we have only sampled the data over the last period
218 * we should now harvest the data. Otherwise just evaluate
219 * the data. The latter should only be performed once
222 if (ant->flags & ANTENNA_MODE_SAMPLE) {
223 rt2x00lib_antenna_diversity_sample(rt2x00dev);
225 } else if (rt2x00dev->link.count & 1) {
226 rt2x00lib_antenna_diversity_eval(rt2x00dev);
233 void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
235 struct rxdone_entry_desc *rxdesc)
237 struct link *link = &rt2x00dev->link;
238 struct link_qual *qual = &rt2x00dev->link.qual;
239 struct link_ant *ant = &rt2x00dev->link.ant;
240 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
243 * Frame was received successfully since non-succesfull
244 * frames would have been dropped by the hardware.
249 * We are only interested in quality statistics from
250 * beacons which came from the BSS which we are
253 if (!ieee80211_is_beacon(hdr->frame_control) ||
254 !(rxdesc->dev_flags & RXDONE_MY_BSS))
260 link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);
263 * Update antenna RSSI
265 ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);
268 void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
270 struct link *link = &rt2x00dev->link;
273 * Link tuning should only be performed when
274 * an active sta or master interface exists.
275 * Single monitor mode interfaces should never have
276 * work with link tuners.
278 if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
281 rt2x00link_reset_tuner(rt2x00dev, false);
283 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
284 ieee80211_queue_delayed_work(rt2x00dev->hw,
285 &link->work, LINK_TUNE_INTERVAL);
288 void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
290 cancel_delayed_work_sync(&rt2x00dev->link.work);
293 void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
295 struct link_qual *qual = &rt2x00dev->link.qual;
297 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
301 * Reset link information.
302 * Both the currently active vgc level as well as
303 * the link tuner counter should be reset. Resetting
304 * the counter is important for devices where the
305 * device should only perform link tuning during the
306 * first minute after being enabled.
308 rt2x00dev->link.count = 0;
309 memset(qual, 0, sizeof(*qual));
312 * Reset the link tuner.
314 rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
317 rt2x00link_antenna_reset(rt2x00dev);
320 static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
322 struct link_qual *qual = &rt2x00dev->link.qual;
324 qual->rx_success = 0;
326 qual->tx_success = 0;
330 static void rt2x00link_tuner(struct work_struct *work)
332 struct rt2x00_dev *rt2x00dev =
333 container_of(work, struct rt2x00_dev, link.work.work);
334 struct link *link = &rt2x00dev->link;
335 struct link_qual *qual = &rt2x00dev->link.qual;
338 * When the radio is shutting down we should
339 * immediately cease all link tuning.
341 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
347 rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
348 rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
351 * Update quality RSSI for link tuning,
352 * when we have received some frames and we managed to
353 * collect the RSSI data we could use this. Otherwise we
354 * must fallback to the default RSSI value.
356 if (!link->avg_rssi.avg || !qual->rx_success)
357 qual->rssi = DEFAULT_RSSI;
359 qual->rssi = link->avg_rssi.avg;
362 * Only perform the link tuning when Link tuning
363 * has been enabled (This could have been disabled from the EEPROM).
365 if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
366 rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
369 * Send a signal to the led to update the led signal strength.
371 rt2x00leds_led_quality(rt2x00dev, qual->rssi);
374 * Evaluate antenna setup, make this the last step when
375 * rt2x00lib_antenna_diversity made changes the quality
376 * statistics will be reset.
378 if (rt2x00lib_antenna_diversity(rt2x00dev))
379 rt2x00link_reset_qual(rt2x00dev);
382 * Increase tuner counter, and reschedule the next link tuner run.
386 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
387 ieee80211_queue_delayed_work(rt2x00dev->hw,
388 &link->work, LINK_TUNE_INTERVAL);
391 void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
393 INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);