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1/*
2 Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
3 <http://rt2x00.serialmonkey.com>
4
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.
9
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.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19/*
20 Module: rt2x00lib
21 Abstract: rt2x00 generic link tuning routines.
22 */
23
24#include <linux/kernel.h>
25#include <linux/module.h>
26
27#include "rt2x00.h"
28#include "rt2x00lib.h"
29
30/*
31 * When we lack RSSI information return something less then -80 to
32 * tell the driver to tune the device to maximum sensitivity.
33 */
34#define DEFAULT_RSSI -128
35
36/* Constants for EWMA calculations. */
37#define RT2X00_EWMA_FACTOR 1024
38#define RT2X00_EWMA_WEIGHT 8
39
40static inline int rt2x00link_get_avg_rssi(struct ewma *ewma)
41{
42 unsigned long avg;
43
44 avg = ewma_read(ewma);
45 if (avg)
46 return -avg;
47
48 return DEFAULT_RSSI;
49}
50
51static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
52{
53 struct link_ant *ant = &rt2x00dev->link.ant;
54
55 if (rt2x00dev->link.qual.rx_success)
56 return rt2x00link_get_avg_rssi(&ant->rssi_ant);
57
58 return DEFAULT_RSSI;
59}
60
61static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
62{
63 struct link_ant *ant = &rt2x00dev->link.ant;
64
65 if (ant->rssi_history)
66 return ant->rssi_history;
67 return DEFAULT_RSSI;
68}
69
70static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
71 int rssi)
72{
73 struct link_ant *ant = &rt2x00dev->link.ant;
74 ant->rssi_history = rssi;
75}
76
77static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
78{
79 ewma_init(&rt2x00dev->link.ant.rssi_ant, RT2X00_EWMA_FACTOR,
80 RT2X00_EWMA_WEIGHT);
81}
82
83static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
84{
85 struct link_ant *ant = &rt2x00dev->link.ant;
86 struct antenna_setup new_ant;
87 int other_antenna;
88
89 int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
90 int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
91
92 memcpy(&new_ant, &ant->active, sizeof(new_ant));
93
94 /*
95 * We are done sampling. Now we should evaluate the results.
96 */
97 ant->flags &= ~ANTENNA_MODE_SAMPLE;
98
99 /*
100 * During the last period we have sampled the RSSI
101 * from both antennas. It now is time to determine
102 * which antenna demonstrated the best performance.
103 * When we are already on the antenna with the best
104 * performance, just create a good starting point
105 * for the history and we are done.
106 */
107 if (sample_current >= sample_other) {
108 rt2x00link_antenna_update_rssi_history(rt2x00dev,
109 sample_current);
110 return;
111 }
112
113 other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
114
115 if (ant->flags & ANTENNA_RX_DIVERSITY)
116 new_ant.rx = other_antenna;
117
118 if (ant->flags & ANTENNA_TX_DIVERSITY)
119 new_ant.tx = other_antenna;
120
121 rt2x00lib_config_antenna(rt2x00dev, new_ant);
122}
123
124static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
125{
126 struct link_ant *ant = &rt2x00dev->link.ant;
127 struct antenna_setup new_ant;
128 int rssi_curr;
129 int rssi_old;
130
131 memcpy(&new_ant, &ant->active, sizeof(new_ant));
132
133 /*
134 * Get current RSSI value along with the historical value,
135 * after that update the history with the current value.
136 */
137 rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
138 rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
139 rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);
140
141 /*
142 * Legacy driver indicates that we should swap antenna's
143 * when the difference in RSSI is greater that 5. This
144 * also should be done when the RSSI was actually better
145 * then the previous sample.
146 * When the difference exceeds the threshold we should
147 * sample the rssi from the other antenna to make a valid
148 * comparison between the 2 antennas.
149 */
150 if (abs(rssi_curr - rssi_old) < 5)
151 return;
152
153 ant->flags |= ANTENNA_MODE_SAMPLE;
154
155 if (ant->flags & ANTENNA_RX_DIVERSITY)
156 new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
157
158 if (ant->flags & ANTENNA_TX_DIVERSITY)
159 new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
160
161 rt2x00lib_config_antenna(rt2x00dev, new_ant);
162}
163
164static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
165{
166 struct link_ant *ant = &rt2x00dev->link.ant;
167
168 /*
169 * Determine if software diversity is enabled for
170 * either the TX or RX antenna (or both).
171 */
172 if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
173 !(ant->flags & ANTENNA_TX_DIVERSITY)) {
174 ant->flags = 0;
175 return true;
176 }
177
178 /*
179 * If we have only sampled the data over the last period
180 * we should now harvest the data. Otherwise just evaluate
181 * the data. The latter should only be performed once
182 * every 2 seconds.
183 */
184 if (ant->flags & ANTENNA_MODE_SAMPLE) {
185 rt2x00lib_antenna_diversity_sample(rt2x00dev);
186 return true;
187 } else if (rt2x00dev->link.count & 1) {
188 rt2x00lib_antenna_diversity_eval(rt2x00dev);
189 return true;
190 }
191
192 return false;
193}
194
195void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
196 struct sk_buff *skb,
197 struct rxdone_entry_desc *rxdesc)
198{
199 struct link *link = &rt2x00dev->link;
200 struct link_qual *qual = &rt2x00dev->link.qual;
201 struct link_ant *ant = &rt2x00dev->link.ant;
202 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
203
204 /*
205 * No need to update the stats for !=STA interfaces
206 */
207 if (!rt2x00dev->intf_sta_count)
208 return;
209
210 /*
211 * Frame was received successfully since non-succesfull
212 * frames would have been dropped by the hardware.
213 */
214 qual->rx_success++;
215
216 /*
217 * We are only interested in quality statistics from
218 * beacons which came from the BSS which we are
219 * associated with.
220 */
221 if (!ieee80211_is_beacon(hdr->frame_control) ||
222 !(rxdesc->dev_flags & RXDONE_MY_BSS))
223 return;
224
225 /*
226 * Update global RSSI
227 */
228 ewma_add(&link->avg_rssi, -rxdesc->rssi);
229
230 /*
231 * Update antenna RSSI
232 */
233 ewma_add(&ant->rssi_ant, -rxdesc->rssi);
234}
235
236void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
237{
238 struct link *link = &rt2x00dev->link;
239
240 /*
241 * Link tuning should only be performed when
242 * an active sta interface exists. AP interfaces
243 * don't need link tuning and monitor mode interfaces
244 * should never have to work with link tuners.
245 */
246 if (!rt2x00dev->intf_sta_count)
247 return;
248
249 /**
250 * While scanning, link tuning is disabled. By default
251 * the most sensitive settings will be used to make sure
252 * that all beacons and probe responses will be received
253 * during the scan.
254 */
255 if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
256 return;
257
258 rt2x00link_reset_tuner(rt2x00dev, false);
259
260 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
261 ieee80211_queue_delayed_work(rt2x00dev->hw,
262 &link->work, LINK_TUNE_INTERVAL);
263}
264
265void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
266{
267 cancel_delayed_work_sync(&rt2x00dev->link.work);
268}
269
270void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
271{
272 struct link_qual *qual = &rt2x00dev->link.qual;
273 u8 vgc_level = qual->vgc_level_reg;
274
275 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
276 return;
277
278 /*
279 * Reset link information.
280 * Both the currently active vgc level as well as
281 * the link tuner counter should be reset. Resetting
282 * the counter is important for devices where the
283 * device should only perform link tuning during the
284 * first minute after being enabled.
285 */
286 rt2x00dev->link.count = 0;
287 memset(qual, 0, sizeof(*qual));
288 ewma_init(&rt2x00dev->link.avg_rssi, RT2X00_EWMA_FACTOR,
289 RT2X00_EWMA_WEIGHT);
290
291 /*
292 * Restore the VGC level as stored in the registers,
293 * the driver can use this to determine if the register
294 * must be updated during reset or not.
295 */
296 qual->vgc_level_reg = vgc_level;
297
298 /*
299 * Reset the link tuner.
300 */
301 rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
302
303 if (antenna)
304 rt2x00link_antenna_reset(rt2x00dev);
305}
306
307static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
308{
309 struct link_qual *qual = &rt2x00dev->link.qual;
310
311 qual->rx_success = 0;
312 qual->rx_failed = 0;
313 qual->tx_success = 0;
314 qual->tx_failed = 0;
315}
316
317static void rt2x00link_tuner(struct work_struct *work)
318{
319 struct rt2x00_dev *rt2x00dev =
320 container_of(work, struct rt2x00_dev, link.work.work);
321 struct link *link = &rt2x00dev->link;
322 struct link_qual *qual = &rt2x00dev->link.qual;
323
324 /*
325 * When the radio is shutting down we should
326 * immediately cease all link tuning.
327 */
328 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags) ||
329 test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
330 return;
331
332 /*
333 * Update statistics.
334 */
335 rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
336 rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
337
338 /*
339 * Update quality RSSI for link tuning,
340 * when we have received some frames and we managed to
341 * collect the RSSI data we could use this. Otherwise we
342 * must fallback to the default RSSI value.
343 */
344 if (!qual->rx_success)
345 qual->rssi = DEFAULT_RSSI;
346 else
347 qual->rssi = rt2x00link_get_avg_rssi(&link->avg_rssi);
348
349 /*
350 * Check if link tuning is supported by the hardware, some hardware
351 * do not support link tuning at all, while other devices can disable
352 * the feature from the EEPROM.
353 */
354 if (rt2x00_has_cap_link_tuning(rt2x00dev))
355 rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
356
357 /*
358 * Send a signal to the led to update the led signal strength.
359 */
360 rt2x00leds_led_quality(rt2x00dev, qual->rssi);
361
362 /*
363 * Evaluate antenna setup, make this the last step when
364 * rt2x00lib_antenna_diversity made changes the quality
365 * statistics will be reset.
366 */
367 if (rt2x00lib_antenna_diversity(rt2x00dev))
368 rt2x00link_reset_qual(rt2x00dev);
369
370 /*
371 * Increase tuner counter, and reschedule the next link tuner run.
372 */
373 link->count++;
374
375 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
376 ieee80211_queue_delayed_work(rt2x00dev->hw,
377 &link->work, LINK_TUNE_INTERVAL);
378}
379
380void rt2x00link_start_watchdog(struct rt2x00_dev *rt2x00dev)
381{
382 struct link *link = &rt2x00dev->link;
383
384 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
385 rt2x00dev->ops->lib->watchdog)
386 ieee80211_queue_delayed_work(rt2x00dev->hw,
387 &link->watchdog_work,
388 WATCHDOG_INTERVAL);
389}
390
391void rt2x00link_stop_watchdog(struct rt2x00_dev *rt2x00dev)
392{
393 cancel_delayed_work_sync(&rt2x00dev->link.watchdog_work);
394}
395
396static void rt2x00link_watchdog(struct work_struct *work)
397{
398 struct rt2x00_dev *rt2x00dev =
399 container_of(work, struct rt2x00_dev, link.watchdog_work.work);
400 struct link *link = &rt2x00dev->link;
401
402 /*
403 * When the radio is shutting down we should
404 * immediately cease the watchdog monitoring.
405 */
406 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
407 return;
408
409 rt2x00dev->ops->lib->watchdog(rt2x00dev);
410
411 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
412 ieee80211_queue_delayed_work(rt2x00dev->hw,
413 &link->watchdog_work,
414 WATCHDOG_INTERVAL);
415}
416
417void rt2x00link_start_agc(struct rt2x00_dev *rt2x00dev)
418{
419 struct link *link = &rt2x00dev->link;
420
421 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
422 rt2x00dev->ops->lib->gain_calibration)
423 ieee80211_queue_delayed_work(rt2x00dev->hw,
424 &link->agc_work,
425 AGC_INTERVAL);
426}
427
428void rt2x00link_start_vcocal(struct rt2x00_dev *rt2x00dev)
429{
430 struct link *link = &rt2x00dev->link;
431
432 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
433 rt2x00dev->ops->lib->vco_calibration)
434 ieee80211_queue_delayed_work(rt2x00dev->hw,
435 &link->vco_work,
436 VCO_INTERVAL);
437}
438
439void rt2x00link_stop_agc(struct rt2x00_dev *rt2x00dev)
440{
441 cancel_delayed_work_sync(&rt2x00dev->link.agc_work);
442}
443
444void rt2x00link_stop_vcocal(struct rt2x00_dev *rt2x00dev)
445{
446 cancel_delayed_work_sync(&rt2x00dev->link.vco_work);
447}
448
449static void rt2x00link_agc(struct work_struct *work)
450{
451 struct rt2x00_dev *rt2x00dev =
452 container_of(work, struct rt2x00_dev, link.agc_work.work);
453 struct link *link = &rt2x00dev->link;
454
455 /*
456 * When the radio is shutting down we should
457 * immediately cease the watchdog monitoring.
458 */
459 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
460 return;
461
462 rt2x00dev->ops->lib->gain_calibration(rt2x00dev);
463
464 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
465 ieee80211_queue_delayed_work(rt2x00dev->hw,
466 &link->agc_work,
467 AGC_INTERVAL);
468}
469
470static void rt2x00link_vcocal(struct work_struct *work)
471{
472 struct rt2x00_dev *rt2x00dev =
473 container_of(work, struct rt2x00_dev, link.vco_work.work);
474 struct link *link = &rt2x00dev->link;
475
476 /*
477 * When the radio is shutting down we should
478 * immediately cease the VCO calibration.
479 */
480 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
481 return;
482
483 rt2x00dev->ops->lib->vco_calibration(rt2x00dev);
484
485 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
486 ieee80211_queue_delayed_work(rt2x00dev->hw,
487 &link->vco_work,
488 VCO_INTERVAL);
489}
490
491void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
492{
493 INIT_DELAYED_WORK(&rt2x00dev->link.agc_work, rt2x00link_agc);
494 if (rt2x00_has_cap_vco_recalibration(rt2x00dev))
495 INIT_DELAYED_WORK(&rt2x00dev->link.vco_work, rt2x00link_vcocal);
496 INIT_DELAYED_WORK(&rt2x00dev->link.watchdog_work, rt2x00link_watchdog);
497 INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
498}