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 /* convert pulse duration to usecs, considering clock mode */
  34 static u32 dur_to_usecs(struct ath_hw *ah, u32 dur)
  35 {
  36         const u32 AR93X_NSECS_PER_DUR = 800;
  37         const u32 AR93X_NSECS_PER_DUR_FAST = (8000 / 11);
  38         u32 nsecs;
  39
  40         if (IS_CHAN_A_FAST_CLOCK(ah, ah->curchan))
  41                 nsecs = dur * AR93X_NSECS_PER_DUR_FAST;
  42         else
  43                 nsecs = dur * AR93X_NSECS_PER_DUR;
  44
  45         return (nsecs + 500) / 1000;
  46 }
  47
  48 #define PRI_CH_RADAR_FOUND 0x01
  49 #define EXT_CH_RADAR_FOUND 0x02
  50 static bool
  51 ath9k_postprocess_radar_event(struct ath_softc *sc,
  52                               struct ath_radar_data *ard,
  53                               struct pulse_event *pe)
  54 {
  55         u8 rssi;
  56         u16 dur;
  57
  58         /*
  59          * Only the last 2 bits of the BW info are relevant, they indicate
  60          * which channel the radar was detected in.
  61          */
  62         ard->pulse_bw_info &= 0x03;
  63
  64         switch (ard->pulse_bw_info) {
  65         case PRI_CH_RADAR_FOUND:
  66                 /* radar in ctrl channel */
  67                 dur = ard->pulse_length_pri;
  68                 DFS_STAT_INC(sc, pri_phy_errors);
  69                 /*
  70                  * cannot use ctrl channel RSSI
  71                  * if extension channel is stronger
  72                  */
  73                 rssi = (ard->ext_rssi >= (ard->rssi + 3)) ? 0 : ard->rssi;
  74                 break;
  75         case EXT_CH_RADAR_FOUND:
  76                 /* radar in extension channel */
  77                 dur = ard->pulse_length_ext;
  78                 DFS_STAT_INC(sc, ext_phy_errors);
  79                 /*
  80                  * cannot use extension channel RSSI
  81                  * if control channel is stronger
  82                  */
  83                 rssi = (ard->rssi >= (ard->ext_rssi + 12)) ? 0 : ard->ext_rssi;
  84                 break;
  85         case (PRI_CH_RADAR_FOUND | EXT_CH_RADAR_FOUND):
  86                 /*
  87                  * Conducted testing, when pulse is on DC, both pri and ext
  88                  * durations are reported to be same
  89                  *
  90                  * Radiated testing, when pulse is on DC, different pri and
  91                  * ext durations are reported, so take the larger of the two
  92                  */
  93                 if (ard->pulse_length_ext >= ard->pulse_length_pri)
  94                         dur = ard->pulse_length_ext;
  95                 else
  96                         dur = ard->pulse_length_pri;
  97                 DFS_STAT_INC(sc, dc_phy_errors);
  98
  99                 /* when both are present use stronger one */
 100                 rssi = (ard->rssi < ard->ext_rssi) ? ard->ext_rssi : ard->rssi;
 101                 break;
 102         default:
 103                 /*
 104                  * Bogus bandwidth info was received in descriptor,
 105                  * so ignore this PHY error
 106                  */
 107                 DFS_STAT_INC(sc, bwinfo_discards);
 108                 return false;
 109         }
 110
 111         if (rssi == 0) {
 112                 DFS_STAT_INC(sc, rssi_discards);
 113                 return false;
 114         }
 115
 116         /*
 117          * TODO: check chirping pulses
 118          *       checks for chirping are dependent on the DFS regulatory domain
 119          *       used, which is yet TBD
 120          */
 121
 122         /* convert duration to usecs */
 123         pe->width = dur_to_usecs(sc->sc_ah, dur);
 124         pe->rssi = rssi;
 125
 126         DFS_STAT_INC(sc, pulses_detected);
 127         return true;
 128 }
 129 #undef PRI_CH_RADAR_FOUND
 130 #undef EXT_CH_RADAR_FOUND
 131
 132 /*
 133  * DFS: check PHY-error for radar pulse and feed the detector
 134  */
 135 void ath9k_dfs_process_phyerr(struct ath_softc *sc, void *data,
 136                               struct ath_rx_status *rs, u64 mactime)
 137 {
 138         struct ath_radar_data ard;
 139         u16 datalen;
 140         char *vdata_end;
 141         struct pulse_event pe;
 142         struct ath_hw *ah = sc->sc_ah;
 143         struct ath_common *common = ath9k_hw_common(ah);
 144
 145         DFS_STAT_INC(sc, pulses_total);
 146         if ((rs->rs_phyerr != ATH9K_PHYERR_RADAR) &&
 147             (rs->rs_phyerr != ATH9K_PHYERR_FALSE_RADAR_EXT)) {
 148                 ath_dbg(common, DFS,
 149                         "Error: rs_phyer=0x%x not a radar error\n",
 150                         rs->rs_phyerr);
 151                 DFS_STAT_INC(sc, pulses_no_dfs);
 152                 return;
 153         }
 154
 155         datalen = rs->rs_datalen;
 156         if (datalen == 0) {
 157                 DFS_STAT_INC(sc, datalen_discards);
 158                 return;
 159         }
 160
 161         ard.rssi = rs->rs_rssi_ctl0;
 162         ard.ext_rssi = rs->rs_rssi_ext0;
 163
 164         /*
 165          * hardware stores this as 8 bit signed value.
 166          * we will cap it at 0 if it is a negative number
 167          */
 168         if (ard.rssi & 0x80)
 169                 ard.rssi = 0;
 170         if (ard.ext_rssi & 0x80)
 171                 ard.ext_rssi = 0;
 172
 173         vdata_end = (char *)data + datalen;
 174         ard.pulse_bw_info = vdata_end[-1];
 175         ard.pulse_length_ext = vdata_end[-2];
 176         ard.pulse_length_pri = vdata_end[-3];
 177         pe.freq = ah->curchan->channel;
 178         pe.ts = mactime;
 179         if (ath9k_postprocess_radar_event(sc, &ard, &pe)) {
 180                 struct dfs_pattern_detector *pd = sc->dfs_detector;
 181                 static u64 last_ts;
 182                 ath_dbg(common, DFS,
 183                         "ath9k_dfs_process_phyerr: channel=%d, ts=%llu, "
 184                         "width=%d, rssi=%d, delta_ts=%llu\n",
 185                         pe.freq, pe.ts, pe.width, pe.rssi, pe.ts-last_ts);
 186                 last_ts = pe.ts;
 187                 DFS_STAT_INC(sc, pulses_processed);
 188                 if (pd != NULL && pd->add_pulse(pd, &pe)) {
 189                         DFS_STAT_INC(sc, radar_detected);
 190                         ieee80211_radar_detected(sc->hw);
 191                 }
 192         }
 193 }