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 unsigned int flags = ant->flags; 192 193 /* 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. 198 */ 199 flags &= ~ANTENNA_RX_DIVERSITY; 200 flags &= ~ANTENNA_TX_DIVERSITY; 201 202 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; 206 207 if (!(ant->flags & ANTENNA_RX_DIVERSITY) && 208 !(ant->flags & ANTENNA_TX_DIVERSITY)) { 209 ant->flags = 0; 210 return true; 211 } 212 213 /* Update flags */ 214 ant->flags = flags; 215 216 /* 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 220 * every 2 seconds. 221 */ 222 if (ant->flags & ANTENNA_MODE_SAMPLE) { 223 rt2x00lib_antenna_diversity_sample(rt2x00dev); 224 return true; 225 } else if (rt2x00dev->link.count & 1) { 226 rt2x00lib_antenna_diversity_eval(rt2x00dev); 227 return true; 228 } 229 230 return false; 231} 232 233void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev, 234 struct sk_buff *skb, 235 struct rxdone_entry_desc *rxdesc) 236{ 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; 241 242 /* 243 * Frame was received successfully since non-succesfull 244 * frames would have been dropped by the hardware. 245 */ 246 qual->rx_success++; 247 248 /* 249 * We are only interested in quality statistics from 250 * beacons which came from the BSS which we are 251 * associated with. 252 */ 253 if (!ieee80211_is_beacon(hdr->frame_control) || 254 !(rxdesc->dev_flags & RXDONE_MY_BSS)) 255 return; 256 257 /* 258 * Update global RSSI 259 */ 260 link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi); 261 262 /* 263 * Update antenna RSSI 264 */ 265 ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi); 266} 267 268void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev) 269{ 270 struct link *link = &rt2x00dev->link; 271 272 /* 273 * Link tuning should only be performed when 274 * an active sta interface exists. AP interfaces 275 * don't need link tuning and monitor mode interfaces 276 * should never have to work with link tuners. 277 */ 278 if (!rt2x00dev->intf_sta_count) 279 return; 280 281 /** 282 * While scanning, link tuning is disabled. By default 283 * the most sensitive settings will be used to make sure 284 * that all beacons and probe responses will be recieved 285 * during the scan. 286 */ 287 if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags)) 288 return; 289 290 rt2x00link_reset_tuner(rt2x00dev, false); 291 292 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags)) 293 ieee80211_queue_delayed_work(rt2x00dev->hw, 294 &link->work, LINK_TUNE_INTERVAL); 295} 296 297void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev) 298{ 299 cancel_delayed_work_sync(&rt2x00dev->link.work); 300} 301 302void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna) 303{ 304 struct link_qual *qual = &rt2x00dev->link.qual; 305 u8 vgc_level = qual->vgc_level_reg; 306 307 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags)) 308 return; 309 310 /* 311 * Reset link information. 312 * Both the currently active vgc level as well as 313 * the link tuner counter should be reset. Resetting 314 * the counter is important for devices where the 315 * device should only perform link tuning during the 316 * first minute after being enabled. 317 */ 318 rt2x00dev->link.count = 0; 319 memset(qual, 0, sizeof(*qual)); 320 321 /* 322 * Restore the VGC level as stored in the registers, 323 * the driver can use this to determine if the register 324 * must be updated during reset or not. 325 */ 326 qual->vgc_level_reg = vgc_level; 327 328 /* 329 * Reset the link tuner. 330 */ 331 rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual); 332 333 if (antenna) 334 rt2x00link_antenna_reset(rt2x00dev); 335} 336 337static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev) 338{ 339 struct link_qual *qual = &rt2x00dev->link.qual; 340 341 qual->rx_success = 0; 342 qual->rx_failed = 0; 343 qual->tx_success = 0; 344 qual->tx_failed = 0; 345} 346 347static void rt2x00link_tuner(struct work_struct *work) 348{ 349 struct rt2x00_dev *rt2x00dev = 350 container_of(work, struct rt2x00_dev, link.work.work); 351 struct link *link = &rt2x00dev->link; 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 test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags)) 360 return; 361 362 /* 363 * Update statistics. 364 */ 365 rt2x00dev->ops->lib->link_stats(rt2x00dev, qual); 366 rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed; 367 368 /* 369 * Update quality RSSI for link tuning, 370 * when we have received some frames and we managed to 371 * collect the RSSI data we could use this. Otherwise we 372 * must fallback to the default RSSI value. 373 */ 374 if (!link->avg_rssi.avg || !qual->rx_success) 375 qual->rssi = DEFAULT_RSSI; 376 else 377 qual->rssi = link->avg_rssi.avg; 378 379 /* 380 * Check if link tuning is supported by the hardware, some hardware 381 * do not support link tuning at all, while other devices can disable 382 * the feature from the EEPROM. 383 */ 384 if (test_bit(DRIVER_SUPPORT_LINK_TUNING, &rt2x00dev->flags)) 385 rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count); 386 387 /* 388 * Send a signal to the led to update the led signal strength. 389 */ 390 rt2x00leds_led_quality(rt2x00dev, qual->rssi); 391 392 /* 393 * Evaluate antenna setup, make this the last step when 394 * rt2x00lib_antenna_diversity made changes the quality 395 * statistics will be reset. 396 */ 397 if (rt2x00lib_antenna_diversity(rt2x00dev)) 398 rt2x00link_reset_qual(rt2x00dev); 399 400 /* 401 * Increase tuner counter, and reschedule the next link tuner run. 402 */ 403 link->count++; 404 405 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags)) 406 ieee80211_queue_delayed_work(rt2x00dev->hw, 407 &link->work, LINK_TUNE_INTERVAL); 408} 409 410void rt2x00link_start_watchdog(struct rt2x00_dev *rt2x00dev) 411{ 412 struct link *link = &rt2x00dev->link; 413 414 if (!test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) || 415 !test_bit(DRIVER_SUPPORT_WATCHDOG, &rt2x00dev->flags)) 416 return; 417 418 ieee80211_queue_delayed_work(rt2x00dev->hw, 419 &link->watchdog_work, WATCHDOG_INTERVAL); 420} 421 422void rt2x00link_stop_watchdog(struct rt2x00_dev *rt2x00dev) 423{ 424 cancel_delayed_work_sync(&rt2x00dev->link.watchdog_work); 425} 426 427static void rt2x00link_watchdog(struct work_struct *work) 428{ 429 struct rt2x00_dev *rt2x00dev = 430 container_of(work, struct rt2x00_dev, link.watchdog_work.work); 431 struct link *link = &rt2x00dev->link; 432 433 /* 434 * When the radio is shutting down we should 435 * immediately cease the watchdog monitoring. 436 */ 437 if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags)) 438 return; 439 440 rt2x00dev->ops->lib->watchdog(rt2x00dev); 441 442 if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags)) 443 ieee80211_queue_delayed_work(rt2x00dev->hw, 444 &link->watchdog_work, WATCHDOG_INTERVAL); 445} 446 447void rt2x00link_register(struct rt2x00_dev *rt2x00dev) 448{ 449 INIT_DELAYED_WORK(&rt2x00dev->link.watchdog_work, rt2x00link_watchdog); 450 INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner); 451} 452