drivers/net/wireless/ath/ath9k/dfs.c

   1 /*
   2  * Copyright (c) 2008-2011 Atheros Communications Inc.
   3  * Copyright (c) 2011 Neratec Solutions AG
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include "hw.h"
  19 #include "hw-ops.h"
  20 #include "ath9k.h"
  21 #include "dfs.h"
  22 #include "dfs_debug.h"
  23
  24 /* internal struct to pass radar data */
  25 struct ath_radar_data {
  26         u8 pulse_bw_info;
  27         u8 rssi;
  28         u8 ext_rssi;
  29         u8 pulse_length_ext;
  30         u8 pulse_length_pri;
  31 };
  32
  33 /**** begin: CHIRP ************************************************************/
  34
  35 /* min and max gradients for defined FCC chirping pulses, given by
  36  * - 20MHz chirp width over a pulse width of  50us
  37  * -  5MHz chirp width over a pulse width of 100us
  38  */
  39 static const int BIN_DELTA_MIN          = 1;
  40 static const int BIN_DELTA_MAX          = 10;
  41
  42 /* we need at least 3 deltas / 4 samples for a reliable chirp detection */
  43 #define NUM_DIFFS 3
  44 static const int FFT_NUM_SAMPLES        = (NUM_DIFFS + 1);
  45
  46 /* Threshold for difference of delta peaks */
  47 static const int MAX_DIFF               = 2;
  48
  49 /* width range to be checked for chirping */
  50 static const int MIN_CHIRP_PULSE_WIDTH  = 20;
  51 static const int MAX_CHIRP_PULSE_WIDTH  = 110;
  52
  53 struct ath9k_dfs_fft_20 {
  54         u8 bin[28];
  55         u8 lower_bins[3];
  56 } __packed;
  57 struct ath9k_dfs_fft_40 {
  58         u8 bin[64];
  59         u8 lower_bins[3];
  60         u8 upper_bins[3];
  61 } __packed;
  62
  63 static inline int fft_max_index(u8 *bins)
  64 {
  65         return (bins[2] & 0xfc) >> 2;
  66 }
  67 static inline int fft_max_magnitude(u8 *bins)
  68 {
  69         return (bins[0] & 0xc0) >> 6 | bins[1] << 2 | (bins[2] & 0x03) << 10;
  70 }
  71 static inline u8 fft_bitmap_weight(u8 *bins)
  72 {
  73         return bins[0] & 0x3f;
  74 }
  75
  76 static int ath9k_get_max_index_ht40(struct ath9k_dfs_fft_40 *fft,
  77                                     bool is_ctl, bool is_ext)
  78 {
  79         const int DFS_UPPER_BIN_OFFSET = 64;
  80         /* if detected radar on both channels, select the significant one */
  81         if (is_ctl && is_ext) {
  82                 /* first check wether channels have 'strong' bins */
  83                 is_ctl = fft_bitmap_weight(fft->lower_bins) != 0;
  84                 is_ext = fft_bitmap_weight(fft->upper_bins) != 0;
  85
  86                 /* if still unclear, take higher magnitude */
  87                 if (is_ctl && is_ext) {
  88                         int mag_lower = fft_max_magnitude(fft->lower_bins);
  89                         int mag_upper = fft_max_magnitude(fft->upper_bins);
  90                         if (mag_upper > mag_lower)
  91                                 is_ctl = false;
  92                         else
  93                                 is_ext = false;
  94                 }
  95         }
  96         if (is_ctl)
  97                 return fft_max_index(fft->lower_bins);
  98         return fft_max_index(fft->upper_bins) + DFS_UPPER_BIN_OFFSET;
  99 }
 100 static bool ath9k_check_chirping(struct ath_softc *sc, u8 *data,
 101                                  int datalen, bool is_ctl, bool is_ext)
 102 {
 103         int i;
 104         int max_bin[FFT_NUM_SAMPLES];
 105         struct ath_hw *ah = sc->sc_ah;
 106         struct ath_common *common = ath9k_hw_common(ah);
 107         int prev_delta;
 108
 109         if (IS_CHAN_HT40(ah->curchan)) {
 110                 struct ath9k_dfs_fft_40 *fft = (struct ath9k_dfs_fft_40 *) data;
 111                 int num_fft_packets = datalen / sizeof(*fft);
 112                 if (num_fft_packets == 0)
 113                         return false;
 114
 115                 ath_dbg(common, DFS, "HT40: datalen=%d, num_fft_packets=%d\n",
 116                         datalen, num_fft_packets);
 117                 if (num_fft_packets < (FFT_NUM_SAMPLES)) {
 118                         ath_dbg(common, DFS, "not enough packets for chirp\n");
 119                         return false;
 120                 }
 121                 /* HW sometimes adds 2 garbage bytes in front of FFT samples */
 122                 if ((datalen % sizeof(*fft)) == 2) {
 123                         fft = (struct ath9k_dfs_fft_40 *) (data + 2);
 124                         ath_dbg(common, DFS, "fixing datalen by 2\n");
 125                 }
 126                 if (IS_CHAN_HT40MINUS(ah->curchan)) {
 127                         int temp = is_ctl;
 128                         is_ctl = is_ext;
 129                         is_ext = temp;
 130                 }
 131                 for (i = 0; i < FFT_NUM_SAMPLES; i++)
 132                         max_bin[i] = ath9k_get_max_index_ht40(fft + i, is_ctl,
 133                                                               is_ext);
 134         } else {
 135                 struct ath9k_dfs_fft_20 *fft = (struct ath9k_dfs_fft_20 *) data;
 136                 int num_fft_packets = datalen / sizeof(*fft);
 137                 if (num_fft_packets == 0)
 138                         return false;
 139                 ath_dbg(common, DFS, "HT20: datalen=%d, num_fft_packets=%d\n",
 140                         datalen, num_fft_packets);
 141                 if (num_fft_packets < (FFT_NUM_SAMPLES)) {
 142                         ath_dbg(common, DFS, "not enough packets for chirp\n");
 143                         return false;
 144                 }
 145                 /* in ht20, this is a 6-bit signed number => shift it to 0 */
 146                 for (i = 0; i < FFT_NUM_SAMPLES; i++)
 147                         max_bin[i] = fft_max_index(fft[i].lower_bins) ^ 0x20;
 148         }
 149         ath_dbg(common, DFS, "bin_max = [%d, %d, %d, %d]\n",
 150                 max_bin[0], max_bin[1], max_bin[2], max_bin[3]);
 151
 152         /* Check for chirp attributes within specs
 153          * a) delta of adjacent max_bins is within range
 154          * b) delta of adjacent deltas are within tolerance
 155          */
 156         prev_delta = 0;
 157         for (i = 0; i < NUM_DIFFS; i++) {
 158                 int ddelta = -1;
 159                 int delta = max_bin[i + 1] - max_bin[i];
 160
 161                 /* ensure gradient is within valid range */
 162                 if (abs(delta) < BIN_DELTA_MIN || abs(delta) > BIN_DELTA_MAX) {
 163                         ath_dbg(common, DFS, "CHIRP: invalid delta %d "
 164                                 "in sample %d\n", delta, i);
 165                         return false;
 166                 }
 167                 if (i == 0)
 168                         goto done;
 169                 ddelta = delta - prev_delta;
 170                 if (abs(ddelta) > MAX_DIFF) {
 171                         ath_dbg(common, DFS, "CHIRP: ddelta %d too high\n",
 172                                 ddelta);
 173                         return false;
 174                 }
 175 done:
 176                 ath_dbg(common, DFS, "CHIRP - %d: delta=%d, ddelta=%d\n",
 177                         i, delta, ddelta);
 178                 prev_delta = delta;
 179         }
 180         return true;
 181 }
 182 /**** end: CHIRP **************************************************************/
 183
 184 /* convert pulse duration to usecs, considering clock mode */
 185 static u32 dur_to_usecs(struct ath_hw *ah, u32 dur)
 186 {
 187         const u32 AR93X_NSECS_PER_DUR = 800;
 188         const u32 AR93X_NSECS_PER_DUR_FAST = (8000 / 11);
 189         u32 nsecs;
 190
 191         if (IS_CHAN_A_FAST_CLOCK(ah, ah->curchan))
 192                 nsecs = dur * AR93X_NSECS_PER_DUR_FAST;
 193         else
 194                 nsecs = dur * AR93X_NSECS_PER_DUR;
 195
 196         return (nsecs + 500) / 1000;
 197 }
 198
 199 #define PRI_CH_RADAR_FOUND 0x01
 200 #define EXT_CH_RADAR_FOUND 0x02
 201 static bool
 202 ath9k_postprocess_radar_event(struct ath_softc *sc,
 203                               struct ath_radar_data *ard,
 204                               struct pulse_event *pe)
 205 {
 206         u8 rssi;
 207         u16 dur;
 208
 209         /*
 210          * Only the last 2 bits of the BW info are relevant, they indicate
 211          * which channel the radar was detected in.
 212          */
 213         ard->pulse_bw_info &= 0x03;
 214
 215         switch (ard->pulse_bw_info) {
 216         case PRI_CH_RADAR_FOUND:
 217                 /* radar in ctrl channel */
 218                 dur = ard->pulse_length_pri;
 219                 DFS_STAT_INC(sc, pri_phy_errors);
 220                 /*
 221                  * cannot use ctrl channel RSSI
 222                  * if extension channel is stronger
 223                  */
 224                 rssi = (ard->ext_rssi >= (ard->rssi + 3)) ? 0 : ard->rssi;
 225                 break;
 226         case EXT_CH_RADAR_FOUND:
 227                 /* radar in extension channel */
 228                 dur = ard->pulse_length_ext;
 229                 DFS_STAT_INC(sc, ext_phy_errors);
 230                 /*
 231                  * cannot use extension channel RSSI
 232                  * if control channel is stronger
 233                  */
 234                 rssi = (ard->rssi >= (ard->ext_rssi + 12)) ? 0 : ard->ext_rssi;
 235                 break;
 236         case (PRI_CH_RADAR_FOUND | EXT_CH_RADAR_FOUND):
 237                 /*
 238                  * Conducted testing, when pulse is on DC, both pri and ext
 239                  * durations are reported to be same
 240                  *
 241                  * Radiated testing, when pulse is on DC, different pri and
 242                  * ext durations are reported, so take the larger of the two
 243                  */
 244                 if (ard->pulse_length_ext >= ard->pulse_length_pri)
 245                         dur = ard->pulse_length_ext;
 246                 else
 247                         dur = ard->pulse_length_pri;
 248                 DFS_STAT_INC(sc, dc_phy_errors);
 249
 250                 /* when both are present use stronger one */
 251                 rssi = (ard->rssi < ard->ext_rssi) ? ard->ext_rssi : ard->rssi;
 252                 break;
 253         default:
 254                 /*
 255                  * Bogus bandwidth info was received in descriptor,
 256                  * so ignore this PHY error
 257                  */
 258                 DFS_STAT_INC(sc, bwinfo_discards);
 259                 return false;
 260         }
 261
 262         if (rssi == 0) {
 263                 DFS_STAT_INC(sc, rssi_discards);
 264                 return false;
 265         }
 266
 267         /* convert duration to usecs */
 268         pe->width = dur_to_usecs(sc->sc_ah, dur);
 269         pe->rssi = rssi;
 270
 271         DFS_STAT_INC(sc, pulses_detected);
 272         return true;
 273 }
 274
 275 static void
 276 ath9k_dfs_process_radar_pulse(struct ath_softc *sc, struct pulse_event *pe)
 277 {
 278         struct dfs_pattern_detector *pd = sc->dfs_detector;
 279         DFS_STAT_INC(sc, pulses_processed);
 280         if (pd == NULL)
 281                 return;
 282         if (!pd->add_pulse(pd, pe))
 283                 return;
 284         DFS_STAT_INC(sc, radar_detected);
 285         ieee80211_radar_detected(sc->hw);
 286 }
 287
 288 /*
 289  * DFS: check PHY-error for radar pulse and feed the detector
 290  */
 291 void ath9k_dfs_process_phyerr(struct ath_softc *sc, void *data,
 292                               struct ath_rx_status *rs, u64 mactime)
 293 {
 294         struct ath_radar_data ard;
 295         u16 datalen;
 296         char *vdata_end;
 297         struct pulse_event pe;
 298         struct ath_hw *ah = sc->sc_ah;
 299         struct ath_common *common = ath9k_hw_common(ah);
 300
 301         DFS_STAT_INC(sc, pulses_total);
 302         if ((rs->rs_phyerr != ATH9K_PHYERR_RADAR) &&
 303             (rs->rs_phyerr != ATH9K_PHYERR_FALSE_RADAR_EXT)) {
 304                 ath_dbg(common, DFS,
 305                         "Error: rs_phyer=0x%x not a radar error\n",
 306                         rs->rs_phyerr);
 307                 DFS_STAT_INC(sc, pulses_no_dfs);
 308                 return;
 309         }
 310
 311         datalen = rs->rs_datalen;
 312         if (datalen == 0) {
 313                 DFS_STAT_INC(sc, datalen_discards);
 314                 return;
 315         }
 316
 317         ard.rssi = rs->rs_rssi_ctl[0];
 318         ard.ext_rssi = rs->rs_rssi_ext[0];
 319
 320         /*
 321          * hardware stores this as 8 bit signed value.
 322          * we will cap it at 0 if it is a negative number
 323          */
 324         if (ard.rssi & 0x80)
 325                 ard.rssi = 0;
 326         if (ard.ext_rssi & 0x80)
 327                 ard.ext_rssi = 0;
 328
 329         vdata_end = (char *)data + datalen;
 330         ard.pulse_bw_info = vdata_end[-1];
 331         ard.pulse_length_ext = vdata_end[-2];
 332         ard.pulse_length_pri = vdata_end[-3];
 333         pe.freq = ah->curchan->channel;
 334         pe.ts = mactime;
 335         if (!ath9k_postprocess_radar_event(sc, &ard, &pe))
 336                 return;
 337
 338         if (pe.width > MIN_CHIRP_PULSE_WIDTH &&
 339             pe.width < MAX_CHIRP_PULSE_WIDTH) {
 340                 bool is_ctl = !!(ard.pulse_bw_info & PRI_CH_RADAR_FOUND);
 341                 bool is_ext = !!(ard.pulse_bw_info & EXT_CH_RADAR_FOUND);
 342                 int clen = datalen - 3;
 343                 pe.chirp = ath9k_check_chirping(sc, data, clen, is_ctl, is_ext);
 344         } else {
 345                 pe.chirp = false;
 346         }
 347
 348         ath_dbg(common, DFS,
 349                 "ath9k_dfs_process_phyerr: type=%d, freq=%d, ts=%llu, "
 350                 "width=%d, rssi=%d, delta_ts=%llu\n",
 351                 ard.pulse_bw_info, pe.freq, pe.ts, pe.width, pe.rssi,
 352                 pe.ts - sc->dfs_prev_pulse_ts);
 353         sc->dfs_prev_pulse_ts = pe.ts;
 354         if (ard.pulse_bw_info & PRI_CH_RADAR_FOUND)
 355                 ath9k_dfs_process_radar_pulse(sc, &pe);
 356         if (IS_CHAN_HT40(ah->curchan) &&
 357             ard.pulse_bw_info & EXT_CH_RADAR_FOUND) {
 358                 pe.freq += IS_CHAN_HT40PLUS(ah->curchan) ? 20 : -20;
 359                 ath9k_dfs_process_radar_pulse(sc, &pe);
 360         }
 361 }
 362 #undef PRI_CH_RADAR_FOUND
 363 #undef EXT_CH_RADAR_FOUND