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

DEFINITIONS

1. fft_max_index
2. fft_max_magnitude
3. fft_bitmap_weight
4. ath9k_get_max_index_ht40
5. ath9k_check_chirping
6. dur_to_usecs
7. ath9k_postprocess_radar_event
8. ath9k_dfs_process_radar_pulse
9. ath9k_dfs_process_phyerr

   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 #define 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                         swap(is_ctl, is_ext);
 128 
 129                 for (i = 0; i < FFT_NUM_SAMPLES; i++)
 130                         max_bin[i] = ath9k_get_max_index_ht40(fft + i, is_ctl,
 131                                                               is_ext);
 132         } else {
 133                 struct ath9k_dfs_fft_20 *fft = (struct ath9k_dfs_fft_20 *) data;
 134                 int num_fft_packets = datalen / sizeof(*fft);
 135                 if (num_fft_packets == 0)
 136                         return false;
 137                 ath_dbg(common, DFS, "HT20: datalen=%d, num_fft_packets=%d\n",
 138                         datalen, num_fft_packets);
 139                 if (num_fft_packets < FFT_NUM_SAMPLES) {
 140                         ath_dbg(common, DFS, "not enough packets for chirp\n");
 141                         return false;
 142                 }
 143                 /* in ht20, this is a 6-bit signed number => shift it to 0 */
 144                 for (i = 0; i < FFT_NUM_SAMPLES; i++)
 145                         max_bin[i] = fft_max_index(fft[i].lower_bins) ^ 0x20;
 146         }
 147         ath_dbg(common, DFS, "bin_max = [%d, %d, %d, %d]\n",
 148                 max_bin[0], max_bin[1], max_bin[2], max_bin[3]);
 149 
 150         /* Check for chirp attributes within specs
 151          * a) delta of adjacent max_bins is within range
 152          * b) delta of adjacent deltas are within tolerance
 153          */
 154         prev_delta = 0;
 155         for (i = 0; i < NUM_DIFFS; i++) {
 156                 int ddelta = -1;
 157                 int delta = max_bin[i + 1] - max_bin[i];
 158 
 159                 /* ensure gradient is within valid range */
 160                 if (abs(delta) < BIN_DELTA_MIN || abs(delta) > BIN_DELTA_MAX) {
 161                         ath_dbg(common, DFS, "CHIRP: invalid delta %d "
 162                                 "in sample %d\n", delta, i);
 163                         return false;
 164                 }
 165                 if (i == 0)
 166                         goto done;
 167                 ddelta = delta - prev_delta;
 168                 if (abs(ddelta) > MAX_DIFF) {
 169                         ath_dbg(common, DFS, "CHIRP: ddelta %d too high\n",
 170                                 ddelta);
 171                         return false;
 172                 }
 173 done:
 174                 ath_dbg(common, DFS, "CHIRP - %d: delta=%d, ddelta=%d\n",
 175                         i, delta, ddelta);
 176                 prev_delta = delta;
 177         }
 178         return true;
 179 }
 180 /**** end: CHIRP **************************************************************/
 181 
 182 /* convert pulse duration to usecs, considering clock mode */
 183 static u32 dur_to_usecs(struct ath_hw *ah, u32 dur)
 184 {
 185         const u32 AR93X_NSECS_PER_DUR = 800;
 186         const u32 AR93X_NSECS_PER_DUR_FAST = (8000 / 11);
 187         u32 nsecs;
 188 
 189         if (IS_CHAN_A_FAST_CLOCK(ah, ah->curchan))
 190                 nsecs = dur * AR93X_NSECS_PER_DUR_FAST;
 191         else
 192                 nsecs = dur * AR93X_NSECS_PER_DUR;
 193 
 194         return (nsecs + 500) / 1000;
 195 }
 196 
 197 #define PRI_CH_RADAR_FOUND 0x01
 198 #define EXT_CH_RADAR_FOUND 0x02
 199 static bool
 200 ath9k_postprocess_radar_event(struct ath_softc *sc,
 201                               struct ath_radar_data *ard,
 202                               struct pulse_event *pe)
 203 {
 204         u8 rssi;
 205         u16 dur;
 206 
 207         /*
 208          * Only the last 2 bits of the BW info are relevant, they indicate
 209          * which channel the radar was detected in.
 210          */
 211         ard->pulse_bw_info &= 0x03;
 212 
 213         switch (ard->pulse_bw_info) {
 214         case PRI_CH_RADAR_FOUND:
 215                 /* radar in ctrl channel */
 216                 dur = ard->pulse_length_pri;
 217                 DFS_STAT_INC(sc, pri_phy_errors);
 218                 /*
 219                  * cannot use ctrl channel RSSI
 220                  * if extension channel is stronger
 221                  */
 222                 rssi = (ard->ext_rssi >= (ard->rssi + 3)) ? 0 : ard->rssi;
 223                 break;
 224         case EXT_CH_RADAR_FOUND:
 225                 /* radar in extension channel */
 226                 dur = ard->pulse_length_ext;
 227                 DFS_STAT_INC(sc, ext_phy_errors);
 228                 /*
 229                  * cannot use extension channel RSSI
 230                  * if control channel is stronger
 231                  */
 232                 rssi = (ard->rssi >= (ard->ext_rssi + 12)) ? 0 : ard->ext_rssi;
 233                 break;
 234         case (PRI_CH_RADAR_FOUND | EXT_CH_RADAR_FOUND):
 235                 /*
 236                  * Conducted testing, when pulse is on DC, both pri and ext
 237                  * durations are reported to be same
 238                  *
 239                  * Radiated testing, when pulse is on DC, different pri and
 240                  * ext durations are reported, so take the larger of the two
 241                  */
 242                 if (ard->pulse_length_ext >= ard->pulse_length_pri)
 243                         dur = ard->pulse_length_ext;
 244                 else
 245                         dur = ard->pulse_length_pri;
 246                 DFS_STAT_INC(sc, dc_phy_errors);
 247 
 248                 /* when both are present use stronger one */
 249                 rssi = (ard->rssi < ard->ext_rssi) ? ard->ext_rssi : ard->rssi;
 250                 break;
 251         default:
 252                 /*
 253                  * Bogus bandwidth info was received in descriptor,
 254                  * so ignore this PHY error
 255                  */
 256                 DFS_STAT_INC(sc, bwinfo_discards);
 257                 return false;
 258         }
 259 
 260         if (rssi == 0) {
 261                 DFS_STAT_INC(sc, rssi_discards);
 262                 return false;
 263         }
 264 
 265         /* convert duration to usecs */
 266         pe->width = dur_to_usecs(sc->sc_ah, dur);
 267         pe->rssi = rssi;
 268 
 269         DFS_STAT_INC(sc, pulses_detected);
 270         return true;
 271 }
 272 
 273 static void
 274 ath9k_dfs_process_radar_pulse(struct ath_softc *sc, struct pulse_event *pe)
 275 {
 276         struct dfs_pattern_detector *pd = sc->dfs_detector;
 277         DFS_STAT_INC(sc, pulses_processed);
 278         if (pd == NULL)
 279                 return;
 280         if (!pd->add_pulse(pd, pe, NULL))
 281                 return;
 282         DFS_STAT_INC(sc, radar_detected);
 283         ieee80211_radar_detected(sc->hw);
 284 }
 285 
 286 /*
 287  * DFS: check PHY-error for radar pulse and feed the detector
 288  */
 289 void ath9k_dfs_process_phyerr(struct ath_softc *sc, void *data,
 290                               struct ath_rx_status *rs, u64 mactime)
 291 {
 292         struct ath_radar_data ard;
 293         u16 datalen;
 294         char *vdata_end;
 295         struct pulse_event pe;
 296         struct ath_hw *ah = sc->sc_ah;
 297         struct ath_common *common = ath9k_hw_common(ah);
 298 
 299         DFS_STAT_INC(sc, pulses_total);
 300         if ((rs->rs_phyerr != ATH9K_PHYERR_RADAR) &&
 301             (rs->rs_phyerr != ATH9K_PHYERR_FALSE_RADAR_EXT)) {
 302                 ath_dbg(common, DFS,
 303                         "Error: rs_phyer=0x%x not a radar error\n",
 304                         rs->rs_phyerr);
 305                 DFS_STAT_INC(sc, pulses_no_dfs);
 306                 return;
 307         }
 308 
 309         datalen = rs->rs_datalen;
 310         if (datalen == 0) {
 311                 DFS_STAT_INC(sc, datalen_discards);
 312                 return;
 313         }
 314 
 315         ard.rssi = rs->rs_rssi_ctl[0];
 316         ard.ext_rssi = rs->rs_rssi_ext[0];
 317 
 318         /*
 319          * hardware stores this as 8 bit signed value.
 320          * we will cap it at 0 if it is a negative number
 321          */
 322         if (ard.rssi & 0x80)
 323                 ard.rssi = 0;
 324         if (ard.ext_rssi & 0x80)
 325                 ard.ext_rssi = 0;
 326 
 327         vdata_end = data + datalen;
 328         ard.pulse_bw_info = vdata_end[-1];
 329         ard.pulse_length_ext = vdata_end[-2];
 330         ard.pulse_length_pri = vdata_end[-3];
 331         pe.freq = ah->curchan->channel;
 332         pe.ts = mactime;
 333         if (!ath9k_postprocess_radar_event(sc, &ard, &pe))
 334                 return;
 335 
 336         if (pe.width > MIN_CHIRP_PULSE_WIDTH &&
 337             pe.width < MAX_CHIRP_PULSE_WIDTH) {
 338                 bool is_ctl = !!(ard.pulse_bw_info & PRI_CH_RADAR_FOUND);
 339                 bool is_ext = !!(ard.pulse_bw_info & EXT_CH_RADAR_FOUND);
 340                 int clen = datalen - 3;
 341                 pe.chirp = ath9k_check_chirping(sc, data, clen, is_ctl, is_ext);
 342         } else {
 343                 pe.chirp = false;
 344         }
 345 
 346         ath_dbg(common, DFS,
 347                 "ath9k_dfs_process_phyerr: type=%d, freq=%d, ts=%llu, "
 348                 "width=%d, rssi=%d, delta_ts=%llu\n",
 349                 ard.pulse_bw_info, pe.freq, pe.ts, pe.width, pe.rssi,
 350                 pe.ts - sc->dfs_prev_pulse_ts);
 351         sc->dfs_prev_pulse_ts = pe.ts;
 352         if (ard.pulse_bw_info & PRI_CH_RADAR_FOUND)
 353                 ath9k_dfs_process_radar_pulse(sc, &pe);
 354         if (IS_CHAN_HT40(ah->curchan) &&
 355             ard.pulse_bw_info & EXT_CH_RADAR_FOUND) {
 356                 pe.freq += IS_CHAN_HT40PLUS(ah->curchan) ? 20 : -20;
 357                 ath9k_dfs_process_radar_pulse(sc, &pe);
 358         }
 359 }
 360 #undef PRI_CH_RADAR_FOUND
 361 #undef EXT_CH_RADAR_FOUND