drivers/net/wireless/rt2x00/rt2x00link.c

   1 /*
   2         Copyright (C) 2004 - 2008 rt2x00 SourceForge Project
   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 static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
  33 {
  34         struct link_ant *ant = &rt2x00dev->link.ant;
  35
  36         if (ant->rssi_ant && rt2x00dev->link.qual.rx_success)
  37                 return ant->rssi_ant;
  38         return DEFAULT_RSSI;
  39 }
  40
  41 static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev,
  42                                                enum antenna antenna)
  43 {
  44         struct link_ant *ant = &rt2x00dev->link.ant;
  45
  46         if (ant->rssi_history[antenna - ANTENNA_A])
  47                 return ant->rssi_history[antenna - ANTENNA_A];
  48         return DEFAULT_RSSI;
  49 }
  50 /* Small wrapper for rt2x00link_antenna_get_rssi_history() */
  51 #define rt2x00link_antenna_get_rssi_rx_history(__dev) \
  52         rt2x00link_antenna_get_rssi_history((__dev), \
  53                                             (__dev)->link.ant.active.rx)
  54 #define rt2x00link_antenna_get_rssi_tx_history(__dev) \
  55         rt2x00link_antenna_get_rssi_history((__dev), \
  56                                             (__dev)->link.ant.active.tx)
  57
  58 static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
  59                                                    enum antenna antenna,
  60                                                    int rssi)
  61 {
  62         struct link_ant *ant = &rt2x00dev->link.ant;
  63         ant->rssi_history[ant->active.rx - ANTENNA_A] = rssi;
  64 }
  65 /* Small wrapper for rt2x00link_antenna_get_rssi_history() */
  66 #define rt2x00link_antenna_update_rssi_rx_history(__dev, __rssi) \
  67         rt2x00link_antenna_update_rssi_history((__dev), \
  68                                                (__dev)->link.ant.active.rx, \
  69                                                (__rssi))
  70 #define rt2x00link_antenna_update_rssi_tx_history(__dev, __rssi) \
  71         rt2x00link_antenna_update_rssi_history((__dev), \
  72                                                (__dev)->link.ant.active.tx, \
  73                                                (__rssi))
  74
  75 static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
  76 {
  77         rt2x00dev->link.ant.rssi_ant = 0;
  78 }
  79
  80 static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
  81 {
  82         struct link_ant *ant = &rt2x00dev->link.ant;
  83         struct antenna_setup new_ant;
  84         int sample_a = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_A);
  85         int sample_b = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_B);
  86
  87         memcpy(&new_ant, &ant->active, sizeof(new_ant));
  88
  89         /*
  90          * We are done sampling. Now we should evaluate the results.
  91          */
  92         ant->flags &= ~ANTENNA_MODE_SAMPLE;
  93
  94         /*
  95          * During the last period we have sampled the RSSI
  96          * from both antenna's. It now is time to determine
  97          * which antenna demonstrated the best performance.
  98          * When we are already on the antenna with the best
  99          * performance, then there really is nothing for us
 100          * left to do.
 101          */
 102         if (sample_a == sample_b)
 103                 return;
 104
 105         if (ant->flags & ANTENNA_RX_DIVERSITY)
 106                 new_ant.rx = (sample_a > sample_b) ? ANTENNA_A : ANTENNA_B;
 107
 108         if (ant->flags & ANTENNA_TX_DIVERSITY)
 109                 new_ant.tx = (sample_a > sample_b) ? ANTENNA_A : ANTENNA_B;
 110
 111         rt2x00lib_config_antenna(rt2x00dev, &new_ant);
 112 }
 113
 114 static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
 115 {
 116         struct link_ant *ant = &rt2x00dev->link.ant;
 117         struct antenna_setup new_ant;
 118         int rssi_curr;
 119         int rssi_old;
 120
 121         memcpy(&new_ant, &ant->active, sizeof(new_ant));
 122
 123         /*
 124          * Get current RSSI value along with the historical value,
 125          * after that update the history with the current value.
 126          */
 127         rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
 128         rssi_old = rt2x00link_antenna_get_rssi_rx_history(rt2x00dev);
 129         rt2x00link_antenna_update_rssi_rx_history(rt2x00dev, rssi_curr);
 130
 131         /*
 132          * Legacy driver indicates that we should swap antenna's
 133          * when the difference in RSSI is greater that 5. This
 134          * also should be done when the RSSI was actually better
 135          * then the previous sample.
 136          * When the difference exceeds the threshold we should
 137          * sample the rssi from the other antenna to make a valid
 138          * comparison between the 2 antennas.
 139          */
 140         if (abs(rssi_curr - rssi_old) < 5)
 141                 return;
 142
 143         ant->flags |= ANTENNA_MODE_SAMPLE;
 144
 145         if (ant->flags & ANTENNA_RX_DIVERSITY)
 146                 new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
 147
 148         if (ant->flags & ANTENNA_TX_DIVERSITY)
 149                 new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
 150
 151         rt2x00lib_config_antenna(rt2x00dev, &new_ant);
 152 }
 153
 154 static void rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
 155 {
 156         struct link_ant *ant = &rt2x00dev->link.ant;
 157
 158         /*
 159          * Determine if software diversity is enabled for
 160          * either the TX or RX antenna (or both).
 161          * Always perform this check since within the link
 162          * tuner interval the configuration might have changed.
 163          */
 164         ant->flags &= ~ANTENNA_RX_DIVERSITY;
 165         ant->flags &= ~ANTENNA_TX_DIVERSITY;
 166
 167         if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
 168                 ant->flags |= ANTENNA_RX_DIVERSITY;
 169         if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
 170                 ant->flags |= ANTENNA_TX_DIVERSITY;
 171
 172         if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
 173             !(ant->flags & ANTENNA_TX_DIVERSITY)) {
 174                 ant->flags = 0;
 175                 return;
 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         else if (rt2x00dev->link.count & 1)
 187                 rt2x00lib_antenna_diversity_eval(rt2x00dev);
 188 }
 189
 190 void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
 191                              struct sk_buff *skb,
 192                              struct rxdone_entry_desc *rxdesc)
 193 {
 194         struct link_qual *qual = &rt2x00dev->link.qual;
 195         struct link_ant *ant = &rt2x00dev->link.ant;
 196         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 197         int avg_rssi = rxdesc->rssi;
 198         int ant_rssi = rxdesc->rssi;
 199
 200         /*
 201          * Frame was received successfully since non-succesfull
 202          * frames would have been dropped by the hardware.
 203          */
 204         qual->rx_success++;
 205
 206         /*
 207          * We are only interested in quality statistics from
 208          * beacons which came from the BSS which we are
 209          * associated with.
 210          */
 211         if (!ieee80211_is_beacon(hdr->frame_control) ||
 212             !(rxdesc->dev_flags & RXDONE_MY_BSS))
 213                 return;
 214
 215         /*
 216          * Update global RSSI
 217          */
 218         if (qual->avg_rssi)
 219                 avg_rssi = MOVING_AVERAGE(qual->avg_rssi, rxdesc->rssi, 8);
 220         qual->avg_rssi = avg_rssi;
 221
 222         /*
 223          * Update antenna RSSI
 224          */
 225         if (ant->rssi_ant)
 226                 ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
 227         ant->rssi_ant = ant_rssi;
 228 }
 229
 230 static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
 231 {
 232         struct link_qual *qual = &rt2x00dev->link.qual;
 233
 234         if (qual->rx_failed || qual->rx_success)
 235                 qual->rx_percentage =
 236                     (qual->rx_success * 100) /
 237                     (qual->rx_failed + qual->rx_success);
 238         else
 239                 qual->rx_percentage = 50;
 240
 241         if (qual->tx_failed || qual->tx_success)
 242                 qual->tx_percentage =
 243                     (qual->tx_success * 100) /
 244                     (qual->tx_failed + qual->tx_success);
 245         else
 246                 qual->tx_percentage = 50;
 247
 248         qual->rx_success = 0;
 249         qual->rx_failed = 0;
 250         qual->tx_success = 0;
 251         qual->tx_failed = 0;
 252 }
 253
 254 int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
 255 {
 256         struct link_qual *qual = &rt2x00dev->link.qual;
 257         int rssi_percentage = 0;
 258         int signal;
 259
 260         /*
 261          * We need a positive value for the RSSI.
 262          */
 263         if (rssi < 0)
 264                 rssi += rt2x00dev->rssi_offset;
 265
 266         /*
 267          * Calculate the different percentages,
 268          * which will be used for the signal.
 269          */
 270         rssi_percentage = (rssi * 100) / rt2x00dev->rssi_offset;
 271
 272         /*
 273          * Add the individual percentages and use the WEIGHT
 274          * defines to calculate the current link signal.
 275          */
 276         signal = ((WEIGHT_RSSI * rssi_percentage) +
 277                   (WEIGHT_TX * qual->tx_percentage) +
 278                   (WEIGHT_RX * qual->rx_percentage)) / 100;
 279
 280         return max_t(int, signal, 100);
 281 }
 282
 283 void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
 284 {
 285         struct link_qual *qual = &rt2x00dev->link.qual;
 286
 287         /*
 288          * Link tuning should only be performed when
 289          * an active sta or master interface exists.
 290          * Single monitor mode interfaces should never have
 291          * work with link tuners.
 292          */
 293         if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
 294                 return;
 295
 296         /*
 297          * Clear all (possibly) pre-existing quality statistics.
 298          */
 299         memset(qual, 0, sizeof(*qual));
 300
 301         /*
 302          * The RX and TX percentage should start at 50%
 303          * this will assure we will get at least get some
 304          * decent value when the link tuner starts.
 305          * The value will be dropped and overwritten with
 306          * the correct (measured) value anyway during the
 307          * first run of the link tuner.
 308          */
 309         qual->rx_percentage = 50;
 310         qual->tx_percentage = 50;
 311
 312         rt2x00link_reset_tuner(rt2x00dev, false);
 313
 314         queue_delayed_work(rt2x00dev->hw->workqueue,
 315                            &rt2x00dev->link.work, LINK_TUNE_INTERVAL);
 316 }
 317
 318 void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
 319 {
 320         cancel_delayed_work_sync(&rt2x00dev->link.work);
 321 }
 322
 323 void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
 324 {
 325         if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 326                 return;
 327
 328         /*
 329          * Reset link information.
 330          * Both the currently active vgc level as well as
 331          * the link tuner counter should be reset. Resetting
 332          * the counter is important for devices where the
 333          * device should only perform link tuning during the
 334          * first minute after being enabled.
 335          */
 336         rt2x00dev->link.count = 0;
 337         rt2x00dev->link.vgc_level = 0;
 338
 339         /*
 340          * Reset the link tuner.
 341          */
 342         rt2x00dev->ops->lib->reset_tuner(rt2x00dev);
 343
 344         if (antenna)
 345                 rt2x00link_antenna_reset(rt2x00dev);
 346 }
 347
 348 static void rt2x00link_tuner(struct work_struct *work)
 349 {
 350         struct rt2x00_dev *rt2x00dev =
 351             container_of(work, struct rt2x00_dev, link.work.work);
 352         struct link_qual *qual = &rt2x00dev->link.qual;
 353
 354         /*
 355          * When the radio is shutting down we should
 356          * immediately cease all link tuning.
 357          */
 358         if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 359                 return;
 360
 361         /*
 362          * Update statistics.
 363          */
 364         rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
 365         rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
 366
 367         /*
 368          * Only perform the link tuning when Link tuning
 369          * has been enabled (This could have been disabled from the EEPROM).
 370          */
 371         if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
 372                 rt2x00dev->ops->lib->link_tuner(rt2x00dev);
 373
 374         /*
 375          * Precalculate a portion of the link signal which is
 376          * in based on the tx/rx success/failure counters.
 377          */
 378         rt2x00link_precalculate_signal(rt2x00dev);
 379
 380         /*
 381          * Send a signal to the led to update the led signal strength.
 382          */
 383         rt2x00leds_led_quality(rt2x00dev, qual->avg_rssi);
 384
 385         /*
 386          * Evaluate antenna setup, make this the last step since this could
 387          * possibly reset some statistics.
 388          */
 389         rt2x00lib_antenna_diversity(rt2x00dev);
 390
 391         /*
 392          * Increase tuner counter, and reschedule the next link tuner run.
 393          */
 394         rt2x00dev->link.count++;
 395         queue_delayed_work(rt2x00dev->hw->workqueue,
 396                            &rt2x00dev->link.work, LINK_TUNE_INTERVAL);
 397 }
 398
 399 void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
 400 {
 401         INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
 402 }