LXR linux/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 */
  25struct 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 */
  39static const int BIN_DELTA_MIN          = 1;
  40static 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 */
  47static const int MAX_DIFF               = 2;
  48
  49/* width range to be checked for chirping */
  50static const int MIN_CHIRP_PULSE_WIDTH  = 20;
  51static const int MAX_CHIRP_PULSE_WIDTH  = 110;
  52
  53struct ath9k_dfs_fft_20 {
  54        u8 bin[28];
  55        u8 lower_bins[3];
  56} __packed;
  57struct ath9k_dfs_fft_40 {
  58        u8 bin[64];
  59        u8 lower_bins[3];
  60        u8 upper_bins[3];
  61} __packed;
  62
  63static inline int fft_max_index(u8 *bins)
  64{
  65        return (bins[2] & 0xfc) >> 2;
  66}
  67static inline int fft_max_magnitude(u8 *bins)
  68{
  69        return (bins[0] & 0xc0) >> 6 | bins[1] << 2 | (bins[2] & 0x03) << 10;
  70}
  71static inline u8 fft_bitmap_weight(u8 *bins)
  72{
  73        return bins[0] & 0x3f;
  74}
  75
  76static 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}
 100static 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                }
 173done:
 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 */
 183static 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
 199static bool
 200ath9k_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
 273static void
 274ath9k_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 */
 289void 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
 362