1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
4 <http://rt2x00.serialmonkey.com>
5
6 */
7
8/*
9 Module: rt2x00lib
10 Abstract: rt2x00 generic link tuning routines.
11 */
12
13#include <linux/kernel.h>
14#include <linux/module.h>
15
16#include "rt2x00.h"
17#include "rt2x00lib.h"
18
19/*
20 * When we lack RSSI information return something less then -80 to
21 * tell the driver to tune the device to maximum sensitivity.
22 */
23#define DEFAULT_RSSI -128
24
25static inline int rt2x00link_get_avg_rssi(struct ewma_rssi *ewma)
26{
27 unsigned long avg;
28
29 avg = ewma_rssi_read(e: ewma);
30 if (avg)
31 return -avg;
32
33 return DEFAULT_RSSI;
34}
35
36static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
37{
38 struct link_ant *ant = &rt2x00dev->link.ant;
39
40 if (rt2x00dev->link.qual.rx_success)
41 return rt2x00link_get_avg_rssi(ewma: &ant->rssi_ant);
42
43 return DEFAULT_RSSI;
44}
45
46static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
47{
48 struct link_ant *ant = &rt2x00dev->link.ant;
49
50 if (ant->rssi_history)
51 return ant->rssi_history;
52 return DEFAULT_RSSI;
53}
54
55static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
56 int rssi)
57{
58 struct link_ant *ant = &rt2x00dev->link.ant;
59 ant->rssi_history = rssi;
60}
61
62static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
63{
64 ewma_rssi_init(e: &rt2x00dev->link.ant.rssi_ant);
65}
66
67static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
68{
69 struct link_ant *ant = &rt2x00dev->link.ant;
70 struct antenna_setup new_ant;
71 int other_antenna;
72
73 int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
74 int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
75
76 memcpy(&new_ant, &ant->active, sizeof(new_ant));
77
78 /*
79 * We are done sampling. Now we should evaluate the results.
80 */
81 ant->flags &= ~ANTENNA_MODE_SAMPLE;
82
83 /*
84 * During the last period we have sampled the RSSI
85 * from both antennas. It now is time to determine
86 * which antenna demonstrated the best performance.
87 * When we are already on the antenna with the best
88 * performance, just create a good starting point
89 * for the history and we are done.
90 */
91 if (sample_current >= sample_other) {
92 rt2x00link_antenna_update_rssi_history(rt2x00dev,
93 rssi: sample_current);
94 return;
95 }
96
97 other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
98
99 if (ant->flags & ANTENNA_RX_DIVERSITY)
100 new_ant.rx = other_antenna;
101
102 if (ant->flags & ANTENNA_TX_DIVERSITY)
103 new_ant.tx = other_antenna;
104
105 rt2x00lib_config_antenna(rt2x00dev, ant: new_ant);
106}
107
108static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
109{
110 struct link_ant *ant = &rt2x00dev->link.ant;
111 struct antenna_setup new_ant;
112 int rssi_curr;
113 int rssi_old;
114
115 memcpy(&new_ant, &ant->active, sizeof(new_ant));
116
117 /*
118 * Get current RSSI value along with the historical value,
119 * after that update the history with the current value.
120 */
121 rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
122 rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
123 rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi: rssi_curr);
124
125 /*
126 * Legacy driver indicates that we should swap antenna's
127 * when the difference in RSSI is greater that 5. This
128 * also should be done when the RSSI was actually better
129 * then the previous sample.
130 * When the difference exceeds the threshold we should
131 * sample the rssi from the other antenna to make a valid
132 * comparison between the 2 antennas.
133 */
134 if (abs(rssi_curr - rssi_old) < 5)
135 return;
136
137 ant->flags |= ANTENNA_MODE_SAMPLE;
138
139 if (ant->flags & ANTENNA_RX_DIVERSITY)
140 new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
141
142 if (ant->flags & ANTENNA_TX_DIVERSITY)
143 new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
144
145 rt2x00lib_config_antenna(rt2x00dev, ant: new_ant);
146}
147
148static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
149{
150 struct link_ant *ant = &rt2x00dev->link.ant;
151
152 /*
153 * Determine if software diversity is enabled for
154 * either the TX or RX antenna (or both).
155 */
156 if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
157 !(ant->flags & ANTENNA_TX_DIVERSITY)) {
158 ant->flags = 0;
159 return true;
160 }
161
162 /*
163 * If we have only sampled the data over the last period
164 * we should now harvest the data. Otherwise just evaluate
165 * the data. The latter should only be performed once
166 * every 2 seconds.
167 */
168 if (ant->flags & ANTENNA_MODE_SAMPLE) {
169 rt2x00lib_antenna_diversity_sample(rt2x00dev);
170 return true;
171 } else if (rt2x00dev->link.count & 1) {
172 rt2x00lib_antenna_diversity_eval(rt2x00dev);
173 return true;
174 }
175
176 return false;
177}
178
179void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
180 struct sk_buff *skb,
181 struct rxdone_entry_desc *rxdesc)
182{
183 struct link *link = &rt2x00dev->link;
184 struct link_qual *qual = &rt2x00dev->link.qual;
185 struct link_ant *ant = &rt2x00dev->link.ant;
186 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
187
188 /*
189 * No need to update the stats for !=STA interfaces
190 */
191 if (!rt2x00dev->intf_sta_count)
192 return;
193
194 /*
195 * Frame was received successfully since non-successful
196 * frames would have been dropped by the hardware.
197 */
198 qual->rx_success++;
199
200 /*
201 * We are only interested in quality statistics from
202 * beacons which came from the BSS which we are
203 * associated with.
204 */
205 if (!ieee80211_is_beacon(fc: hdr->frame_control) ||
206 !(rxdesc->dev_flags & RXDONE_MY_BSS))
207 return;
208
209 /*
210 * Update global RSSI
211 */
212 ewma_rssi_add(e: &link->avg_rssi, val: -rxdesc->rssi);
213
214 /*
215 * Update antenna RSSI
216 */
217 ewma_rssi_add(e: &ant->rssi_ant, val: -rxdesc->rssi);
218}
219
220void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
221{
222 struct link *link = &rt2x00dev->link;
223
224 /*
225 * Single monitor mode interfaces should never have
226 * work with link tuners.
227 */
228 if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
229 return;
230
231 /*
232 * While scanning, link tuning is disabled. By default
233 * the most sensitive settings will be used to make sure
234 * that all beacons and probe responses will be received
235 * during the scan.
236 */
237 if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
238 return;
239
240 rt2x00link_reset_tuner(rt2x00dev, antenna: false);
241
242 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
243 ieee80211_queue_delayed_work(hw: rt2x00dev->hw,
244 dwork: &link->work, LINK_TUNE_INTERVAL);
245}
246
247void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
248{
249 cancel_delayed_work_sync(dwork: &rt2x00dev->link.work);
250}
251
252void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
253{
254 struct link_qual *qual = &rt2x00dev->link.qual;
255 u8 vgc_level = qual->vgc_level_reg;
256
257 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
258 return;
259
260 /*
261 * Reset link information.
262 * Both the currently active vgc level as well as
263 * the link tuner counter should be reset. Resetting
264 * the counter is important for devices where the
265 * device should only perform link tuning during the
266 * first minute after being enabled.
267 */
268 rt2x00dev->link.count = 0;
269 memset(qual, 0, sizeof(*qual));
270 ewma_rssi_init(e: &rt2x00dev->link.avg_rssi);
271
272 /*
273 * Restore the VGC level as stored in the registers,
274 * the driver can use this to determine if the register
275 * must be updated during reset or not.
276 */
277 qual->vgc_level_reg = vgc_level;
278
279 /*
280 * Reset the link tuner.
281 */
282 rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
283
284 if (antenna)
285 rt2x00link_antenna_reset(rt2x00dev);
286}
287
288static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
289{
290 struct link_qual *qual = &rt2x00dev->link.qual;
291
292 qual->rx_success = 0;
293 qual->rx_failed = 0;
294 qual->tx_success = 0;
295 qual->tx_failed = 0;
296}
297
298static void rt2x00link_tuner_sta(struct rt2x00_dev *rt2x00dev, struct link *link)
299{
300 struct link_qual *qual = &rt2x00dev->link.qual;
301
302 /*
303 * Update statistics.
304 */
305 rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
306 rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
307
308 /*
309 * Update quality RSSI for link tuning,
310 * when we have received some frames and we managed to
311 * collect the RSSI data we could use this. Otherwise we
312 * must fallback to the default RSSI value.
313 */
314 if (!qual->rx_success)
315 qual->rssi = DEFAULT_RSSI;
316 else
317 qual->rssi = rt2x00link_get_avg_rssi(ewma: &link->avg_rssi);
318
319 /*
320 * Check if link tuning is supported by the hardware, some hardware
321 * do not support link tuning at all, while other devices can disable
322 * the feature from the EEPROM.
323 */
324 if (rt2x00_has_cap_link_tuning(rt2x00dev))
325 rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
326
327 /*
328 * Send a signal to the led to update the led signal strength.
329 */
330 rt2x00leds_led_quality(rt2x00dev, rssi: qual->rssi);
331
332 /*
333 * Evaluate antenna setup, make this the last step when
334 * rt2x00lib_antenna_diversity made changes the quality
335 * statistics will be reset.
336 */
337 if (rt2x00lib_antenna_diversity(rt2x00dev))
338 rt2x00link_reset_qual(rt2x00dev);
339}
340
341static void rt2x00link_tuner(struct work_struct *work)
342{
343 struct rt2x00_dev *rt2x00dev =
344 container_of(work, struct rt2x00_dev, link.work.work);
345 struct link *link = &rt2x00dev->link;
346
347 /*
348 * When the radio is shutting down we should
349 * immediately cease all link tuning.
350 */
351 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags) ||
352 test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
353 return;
354
355 /* Do not race with rt2x00mac_config(). */
356 mutex_lock(&rt2x00dev->conf_mutex);
357
358 if (rt2x00dev->intf_sta_count)
359 rt2x00link_tuner_sta(rt2x00dev, link);
360
361 if (rt2x00dev->ops->lib->gain_calibration &&
362 (link->count % (AGC_SECONDS / LINK_TUNE_SECONDS)) == 0)
363 rt2x00dev->ops->lib->gain_calibration(rt2x00dev);
364
365 if (rt2x00dev->ops->lib->vco_calibration &&
366 rt2x00_has_cap_vco_recalibration(rt2x00dev) &&
367 (link->count % (VCO_SECONDS / LINK_TUNE_SECONDS)) == 0)
368 rt2x00dev->ops->lib->vco_calibration(rt2x00dev);
369
370 mutex_unlock(lock: &rt2x00dev->conf_mutex);
371
372 /*
373 * Increase tuner counter, and reschedule the next link tuner run.
374 */
375 link->count++;
376
377 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
378 ieee80211_queue_delayed_work(hw: rt2x00dev->hw,
379 dwork: &link->work, LINK_TUNE_INTERVAL);
380}
381
382void rt2x00link_start_watchdog(struct rt2x00_dev *rt2x00dev)
383{
384 struct link *link = &rt2x00dev->link;
385
386 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
387 rt2x00dev->ops->lib->watchdog && link->watchdog)
388 ieee80211_queue_delayed_work(hw: rt2x00dev->hw,
389 dwork: &link->watchdog_work,
390 delay: link->watchdog_interval);
391}
392
393void rt2x00link_stop_watchdog(struct rt2x00_dev *rt2x00dev)
394{
395 cancel_delayed_work_sync(dwork: &rt2x00dev->link.watchdog_work);
396}
397
398static void rt2x00link_watchdog(struct work_struct *work)
399{
400 struct rt2x00_dev *rt2x00dev =
401 container_of(work, struct rt2x00_dev, link.watchdog_work.work);
402 struct link *link = &rt2x00dev->link;
403
404 /*
405 * When the radio is shutting down we should
406 * immediately cease the watchdog monitoring.
407 */
408 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
409 return;
410
411 rt2x00dev->ops->lib->watchdog(rt2x00dev);
412
413 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
414 ieee80211_queue_delayed_work(hw: rt2x00dev->hw,
415 dwork: &link->watchdog_work,
416 delay: link->watchdog_interval);
417}
418
419void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
420{
421 struct link *link = &rt2x00dev->link;
422
423 INIT_DELAYED_WORK(&link->work, rt2x00link_tuner);
424 INIT_DELAYED_WORK(&link->watchdog_work, rt2x00link_watchdog);
425
426 if (link->watchdog_interval == 0)
427 link->watchdog_interval = WATCHDOG_INTERVAL;
428}
429

source code of linux/drivers/net/wireless/ralink/rt2x00/rt2x00link.c