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/drivers/net/wireless/rt2x00/rt2x00link.c

http://github.com/mirrors/linux
C | 520 lines | 266 code | 83 blank | 171 comment | 39 complexity | fd78944ab60b5a1b612ddc746aeeece3 MD5 | raw file
  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, write to the
 17	Free Software Foundation, Inc.,
 18	59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 19 */
 20
 21/*
 22	Module: rt2x00lib
 23	Abstract: rt2x00 generic link tuning routines.
 24 */
 25
 26#include <linux/kernel.h>
 27#include <linux/module.h>
 28
 29#include "rt2x00.h"
 30#include "rt2x00lib.h"
 31
 32/*
 33 * When we lack RSSI information return something less then -80 to
 34 * tell the driver to tune the device to maximum sensitivity.
 35 */
 36#define DEFAULT_RSSI		-128
 37
 38/*
 39 * Helper struct and macro to work with moving/walking averages.
 40 * When adding a value to the average value the following calculation
 41 * is needed:
 42 *
 43 *        avg_rssi = ((avg_rssi * 7) + rssi) / 8;
 44 *
 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.
 60 */
 61#define AVG_SAMPLES	8
 62#define AVG_FACTOR	1000
 63#define MOVING_AVERAGE(__avg, __val) \
 64({ \
 65	struct avg_val __new; \
 66	__new.avg_weight = \
 67	    (__avg).avg_weight  ? \
 68		((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \
 69		  ((__val) * (AVG_FACTOR))) / \
 70		 (AVG_SAMPLES)) : \
 71		((__val) * (AVG_FACTOR)); \
 72	__new.avg = __new.avg_weight / (AVG_FACTOR); \
 73	__new; \
 74})
 75
 76static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
 77{
 78	struct link_ant *ant = &rt2x00dev->link.ant;
 79
 80	if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)
 81		return ant->rssi_ant.avg;
 82	return DEFAULT_RSSI;
 83}
 84
 85static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
 86{
 87	struct link_ant *ant = &rt2x00dev->link.ant;
 88
 89	if (ant->rssi_history)
 90		return ant->rssi_history;
 91	return DEFAULT_RSSI;
 92}
 93
 94static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
 95						   int rssi)
 96{
 97	struct link_ant *ant = &rt2x00dev->link.ant;
 98	ant->rssi_history = rssi;
 99}
100
101static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
102{
103	rt2x00dev->link.ant.rssi_ant.avg = 0;
104	rt2x00dev->link.ant.rssi_ant.avg_weight = 0;
105}
106
107static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
108{
109	struct link_ant *ant = &rt2x00dev->link.ant;
110	struct antenna_setup new_ant;
111	int other_antenna;
112
113	int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
114	int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
115
116	memcpy(&new_ant, &ant->active, sizeof(new_ant));
117
118	/*
119	 * We are done sampling. Now we should evaluate the results.
120	 */
121	ant->flags &= ~ANTENNA_MODE_SAMPLE;
122
123	/*
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.
130	 */
131	if (sample_current >= sample_other) {
132		rt2x00link_antenna_update_rssi_history(rt2x00dev,
133			sample_current);
134		return;
135	}
136
137	other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
138
139	if (ant->flags & ANTENNA_RX_DIVERSITY)
140		new_ant.rx = other_antenna;
141
142	if (ant->flags & ANTENNA_TX_DIVERSITY)
143		new_ant.tx = other_antenna;
144
145	rt2x00lib_config_antenna(rt2x00dev, new_ant);
146}
147
148static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
149{
150	struct link_ant *ant = &rt2x00dev->link.ant;
151	struct antenna_setup new_ant;
152	int rssi_curr;
153	int rssi_old;
154
155	memcpy(&new_ant, &ant->active, sizeof(new_ant));
156
157	/*
158	 * Get current RSSI value along with the historical value,
159	 * after that update the history with the current value.
160	 */
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);
164
165	/*
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.
173	 */
174	if (abs(rssi_curr - rssi_old) < 5)
175		return;
176
177	ant->flags |= ANTENNA_MODE_SAMPLE;
178
179	if (ant->flags & ANTENNA_RX_DIVERSITY)
180		new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
181
182	if (ant->flags & ANTENNA_TX_DIVERSITY)
183		new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
184
185	rt2x00lib_config_antenna(rt2x00dev, new_ant);
186}
187
188static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
189{
190	struct link_ant *ant = &rt2x00dev->link.ant;
191
192	/*
193	 * Determine if software diversity is enabled for
194	 * either the TX or RX antenna (or both).
195	 */
196	if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
197	    !(ant->flags & ANTENNA_TX_DIVERSITY)) {
198		ant->flags = 0;
199		return true;
200	}
201
202	/*
203	 * If we have only sampled the data over the last period
204	 * we should now harvest the data. Otherwise just evaluate
205	 * the data. The latter should only be performed once
206	 * every 2 seconds.
207	 */
208	if (ant->flags & ANTENNA_MODE_SAMPLE) {
209		rt2x00lib_antenna_diversity_sample(rt2x00dev);
210		return true;
211	} else if (rt2x00dev->link.count & 1) {
212		rt2x00lib_antenna_diversity_eval(rt2x00dev);
213		return true;
214	}
215
216	return false;
217}
218
219void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
220			     struct sk_buff *skb,
221			     struct rxdone_entry_desc *rxdesc)
222{
223	struct link *link = &rt2x00dev->link;
224	struct link_qual *qual = &rt2x00dev->link.qual;
225	struct link_ant *ant = &rt2x00dev->link.ant;
226	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
227
228	/*
229	 * No need to update the stats for !=STA interfaces
230	 */
231	if (!rt2x00dev->intf_sta_count)
232		return;
233
234	/*
235	 * Frame was received successfully since non-succesfull
236	 * frames would have been dropped by the hardware.
237	 */
238	qual->rx_success++;
239
240	/*
241	 * We are only interested in quality statistics from
242	 * beacons which came from the BSS which we are
243	 * associated with.
244	 */
245	if (!ieee80211_is_beacon(hdr->frame_control) ||
246	    !(rxdesc->dev_flags & RXDONE_MY_BSS))
247		return;
248
249	/*
250	 * Update global RSSI
251	 */
252	link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);
253
254	/*
255	 * Update antenna RSSI
256	 */
257	ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);
258}
259
260void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
261{
262	struct link *link = &rt2x00dev->link;
263
264	/*
265	 * Link tuning should only be performed when
266	 * an active sta interface exists. AP interfaces
267	 * don't need link tuning and monitor mode interfaces
268	 * should never have to work with link tuners.
269	 */
270	if (!rt2x00dev->intf_sta_count)
271		return;
272
273	/**
274	 * While scanning, link tuning is disabled. By default
275	 * the most sensitive settings will be used to make sure
276	 * that all beacons and probe responses will be received
277	 * during the scan.
278	 */
279	if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
280		return;
281
282	rt2x00link_reset_tuner(rt2x00dev, false);
283
284	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
285		ieee80211_queue_delayed_work(rt2x00dev->hw,
286					     &link->work, LINK_TUNE_INTERVAL);
287}
288
289void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
290{
291	cancel_delayed_work_sync(&rt2x00dev->link.work);
292}
293
294void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
295{
296	struct link_qual *qual = &rt2x00dev->link.qual;
297	u8 vgc_level = qual->vgc_level_reg;
298
299	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
300		return;
301
302	/*
303	 * Reset link information.
304	 * Both the currently active vgc level as well as
305	 * the link tuner counter should be reset. Resetting
306	 * the counter is important for devices where the
307	 * device should only perform link tuning during the
308	 * first minute after being enabled.
309	 */
310	rt2x00dev->link.count = 0;
311	memset(qual, 0, sizeof(*qual));
312
313	/*
314	 * Restore the VGC level as stored in the registers,
315	 * the driver can use this to determine if the register
316	 * must be updated during reset or not.
317	 */
318	qual->vgc_level_reg = vgc_level;
319
320	/*
321	 * Reset the link tuner.
322	 */
323	rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
324
325	if (antenna)
326		rt2x00link_antenna_reset(rt2x00dev);
327}
328
329static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
330{
331	struct link_qual *qual = &rt2x00dev->link.qual;
332
333	qual->rx_success = 0;
334	qual->rx_failed = 0;
335	qual->tx_success = 0;
336	qual->tx_failed = 0;
337}
338
339static void rt2x00link_tuner(struct work_struct *work)
340{
341	struct rt2x00_dev *rt2x00dev =
342	    container_of(work, struct rt2x00_dev, link.work.work);
343	struct link *link = &rt2x00dev->link;
344	struct link_qual *qual = &rt2x00dev->link.qual;
345
346	/*
347	 * When the radio is shutting down we should
348	 * immediately cease all link tuning.
349	 */
350	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags) ||
351	    test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
352		return;
353
354	/*
355	 * Update statistics.
356	 */
357	rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
358	rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
359
360	/*
361	 * Update quality RSSI for link tuning,
362	 * when we have received some frames and we managed to
363	 * collect the RSSI data we could use this. Otherwise we
364	 * must fallback to the default RSSI value.
365	 */
366	if (!link->avg_rssi.avg || !qual->rx_success)
367		qual->rssi = DEFAULT_RSSI;
368	else
369		qual->rssi = link->avg_rssi.avg;
370
371	/*
372	 * Check if link tuning is supported by the hardware, some hardware
373	 * do not support link tuning at all, while other devices can disable
374	 * the feature from the EEPROM.
375	 */
376	if (test_bit(CAPABILITY_LINK_TUNING, &rt2x00dev->cap_flags))
377		rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
378
379	/*
380	 * Send a signal to the led to update the led signal strength.
381	 */
382	rt2x00leds_led_quality(rt2x00dev, qual->rssi);
383
384	/*
385	 * Evaluate antenna setup, make this the last step when
386	 * rt2x00lib_antenna_diversity made changes the quality
387	 * statistics will be reset.
388	 */
389	if (rt2x00lib_antenna_diversity(rt2x00dev))
390		rt2x00link_reset_qual(rt2x00dev);
391
392	/*
393	 * Increase tuner counter, and reschedule the next link tuner run.
394	 */
395	link->count++;
396
397	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
398		ieee80211_queue_delayed_work(rt2x00dev->hw,
399					     &link->work, LINK_TUNE_INTERVAL);
400}
401
402void rt2x00link_start_watchdog(struct rt2x00_dev *rt2x00dev)
403{
404	struct link *link = &rt2x00dev->link;
405
406	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
407	    rt2x00dev->ops->lib->watchdog)
408		ieee80211_queue_delayed_work(rt2x00dev->hw,
409					     &link->watchdog_work,
410					     WATCHDOG_INTERVAL);
411}
412
413void rt2x00link_stop_watchdog(struct rt2x00_dev *rt2x00dev)
414{
415	cancel_delayed_work_sync(&rt2x00dev->link.watchdog_work);
416}
417
418static void rt2x00link_watchdog(struct work_struct *work)
419{
420	struct rt2x00_dev *rt2x00dev =
421	    container_of(work, struct rt2x00_dev, link.watchdog_work.work);
422	struct link *link = &rt2x00dev->link;
423
424	/*
425	 * When the radio is shutting down we should
426	 * immediately cease the watchdog monitoring.
427	 */
428	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
429		return;
430
431	rt2x00dev->ops->lib->watchdog(rt2x00dev);
432
433	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
434		ieee80211_queue_delayed_work(rt2x00dev->hw,
435					     &link->watchdog_work,
436					     WATCHDOG_INTERVAL);
437}
438
439void rt2x00link_start_agc(struct rt2x00_dev *rt2x00dev)
440{
441	struct link *link = &rt2x00dev->link;
442
443	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
444	    rt2x00dev->ops->lib->gain_calibration)
445		ieee80211_queue_delayed_work(rt2x00dev->hw,
446					     &link->agc_work,
447					     AGC_INTERVAL);
448}
449
450void rt2x00link_start_vcocal(struct rt2x00_dev *rt2x00dev)
451{
452	struct link *link = &rt2x00dev->link;
453
454	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
455	    rt2x00dev->ops->lib->vco_calibration)
456		ieee80211_queue_delayed_work(rt2x00dev->hw,
457					     &link->vco_work,
458					     VCO_INTERVAL);
459}
460
461void rt2x00link_stop_agc(struct rt2x00_dev *rt2x00dev)
462{
463	cancel_delayed_work_sync(&rt2x00dev->link.agc_work);
464}
465
466void rt2x00link_stop_vcocal(struct rt2x00_dev *rt2x00dev)
467{
468	cancel_delayed_work_sync(&rt2x00dev->link.vco_work);
469}
470
471static void rt2x00link_agc(struct work_struct *work)
472{
473	struct rt2x00_dev *rt2x00dev =
474	    container_of(work, struct rt2x00_dev, link.agc_work.work);
475	struct link *link = &rt2x00dev->link;
476
477	/*
478	 * When the radio is shutting down we should
479	 * immediately cease the watchdog monitoring.
480	 */
481	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
482		return;
483
484	rt2x00dev->ops->lib->gain_calibration(rt2x00dev);
485
486	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
487		ieee80211_queue_delayed_work(rt2x00dev->hw,
488					     &link->agc_work,
489					     AGC_INTERVAL);
490}
491
492static void rt2x00link_vcocal(struct work_struct *work)
493{
494	struct rt2x00_dev *rt2x00dev =
495	    container_of(work, struct rt2x00_dev, link.vco_work.work);
496	struct link *link = &rt2x00dev->link;
497
498	/*
499	 * When the radio is shutting down we should
500	 * immediately cease the VCO calibration.
501	 */
502	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
503		return;
504
505	rt2x00dev->ops->lib->vco_calibration(rt2x00dev);
506
507	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
508		ieee80211_queue_delayed_work(rt2x00dev->hw,
509					     &link->vco_work,
510					     VCO_INTERVAL);
511}
512
513void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
514{
515	INIT_DELAYED_WORK(&rt2x00dev->link.agc_work, rt2x00link_agc);
516	if (test_bit(CAPABILITY_VCO_RECALIBRATION, &rt2x00dev->cap_flags))
517		INIT_DELAYED_WORK(&rt2x00dev->link.vco_work, rt2x00link_vcocal);
518	INIT_DELAYED_WORK(&rt2x00dev->link.watchdog_work, rt2x00link_watchdog);
519	INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
520}