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

   1 /*
   2  * Copyright (c) 2009 Atheros Communications Inc.
   3  *
   4  * Permission to use, copy, modify, and/or distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 /*
  18  * Module for common driver code between ath9k and ath9k_htc
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23
  24 #include "common.h"
  25
  26 MODULE_AUTHOR("Atheros Communications");
  27 MODULE_DESCRIPTION("Shared library for Atheros wireless 802.11n LAN cards.");
  28 MODULE_LICENSE("Dual BSD/GPL");
  29
  30 /* Common RX processing */
  31
  32 /* Assumes you've already done the endian to CPU conversion */
  33 static bool ath9k_rx_accept(struct ath_common *common,
  34                             struct sk_buff *skb,
  35                             struct ieee80211_rx_status *rxs,
  36                             struct ath_rx_status *rx_stats,
  37                             bool *decrypt_error)
  38 {
  39         struct ath_hw *ah = common->ah;
  40         struct ieee80211_hdr *hdr;
  41         __le16 fc;
  42
  43         hdr = (struct ieee80211_hdr *) skb->data;
  44         fc = hdr->frame_control;
  45
  46         if (!rx_stats->rs_datalen)
  47                 return false;
  48         /*
  49          * rs_status follows rs_datalen so if rs_datalen is too large
  50          * we can take a hint that hardware corrupted it, so ignore
  51          * those frames.
  52          */
  53         if (rx_stats->rs_datalen > common->rx_bufsize)
  54                 return false;
  55
  56         /*
  57          * rs_more indicates chained descriptors which can be used
  58          * to link buffers together for a sort of scatter-gather
  59          * operation.
  60          *
  61          * The rx_stats->rs_status will not be set until the end of the
  62          * chained descriptors so it can be ignored if rs_more is set. The
  63          * rs_more will be false at the last element of the chained
  64          * descriptors.
  65          */
  66         if (!rx_stats->rs_more && rx_stats->rs_status != 0) {
  67                 if (rx_stats->rs_status & ATH9K_RXERR_CRC)
  68                         rxs->flag |= RX_FLAG_FAILED_FCS_CRC;
  69                 if (rx_stats->rs_status & ATH9K_RXERR_PHY)
  70                         return false;
  71
  72                 if (rx_stats->rs_status & ATH9K_RXERR_DECRYPT) {
  73                         *decrypt_error = true;
  74                 } else if (rx_stats->rs_status & ATH9K_RXERR_MIC) {
  75                         if (ieee80211_is_ctl(fc))
  76                                 /*
  77                                  * Sometimes, we get invalid
  78                                  * MIC failures on valid control frames.
  79                                  * Remove these mic errors.
  80                                  */
  81                                 rx_stats->rs_status &= ~ATH9K_RXERR_MIC;
  82                         else
  83                                 rxs->flag |= RX_FLAG_MMIC_ERROR;
  84                 }
  85                 /*
  86                  * Reject error frames with the exception of
  87                  * decryption and MIC failures. For monitor mode,
  88                  * we also ignore the CRC error.
  89                  */
  90                 if (ah->opmode == NL80211_IFTYPE_MONITOR) {
  91                         if (rx_stats->rs_status &
  92                             ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC |
  93                               ATH9K_RXERR_CRC))
  94                                 return false;
  95                 } else {
  96                         if (rx_stats->rs_status &
  97                             ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC)) {
  98                                 return false;
  99                         }
 100                 }
 101         }
 102         return true;
 103 }
 104
 105 static u8 ath9k_process_rate(struct ath_common *common,
 106                              struct ieee80211_hw *hw,
 107                              struct ath_rx_status *rx_stats,
 108                              struct ieee80211_rx_status *rxs,
 109                              struct sk_buff *skb)
 110 {
 111         struct ieee80211_supported_band *sband;
 112         enum ieee80211_band band;
 113         unsigned int i = 0;
 114
 115         band = hw->conf.channel->band;
 116         sband = hw->wiphy->bands[band];
 117
 118         if (rx_stats->rs_rate & 0x80) {
 119                 /* HT rate */
 120                 rxs->flag |= RX_FLAG_HT;
 121                 if (rx_stats->rs_flags & ATH9K_RX_2040)
 122                         rxs->flag |= RX_FLAG_40MHZ;
 123                 if (rx_stats->rs_flags & ATH9K_RX_GI)
 124                         rxs->flag |= RX_FLAG_SHORT_GI;
 125                 return rx_stats->rs_rate & 0x7f;
 126         }
 127
 128         for (i = 0; i < sband->n_bitrates; i++) {
 129                 if (sband->bitrates[i].hw_value == rx_stats->rs_rate)
 130                         return i;
 131                 if (sband->bitrates[i].hw_value_short == rx_stats->rs_rate) {
 132                         rxs->flag |= RX_FLAG_SHORTPRE;
 133                         return i;
 134                 }
 135         }
 136
 137         /* No valid hardware bitrate found -- we should not get here */
 138         ath_print(common, ATH_DBG_XMIT, "unsupported hw bitrate detected "
 139                   "0x%02x using 1 Mbit\n", rx_stats->rs_rate);
 140         if ((common->debug_mask & ATH_DBG_XMIT))
 141                 print_hex_dump_bytes("", DUMP_PREFIX_NONE, skb->data, skb->len);
 142
 143         return 0;
 144 }
 145
 146 static void ath9k_process_rssi(struct ath_common *common,
 147                                struct ieee80211_hw *hw,
 148                                struct sk_buff *skb,
 149                                struct ath_rx_status *rx_stats)
 150 {
 151         struct ath_hw *ah = common->ah;
 152         struct ieee80211_sta *sta;
 153         struct ieee80211_hdr *hdr;
 154         struct ath_node *an;
 155         int last_rssi = ATH_RSSI_DUMMY_MARKER;
 156         __le16 fc;
 157
 158         hdr = (struct ieee80211_hdr *)skb->data;
 159         fc = hdr->frame_control;
 160
 161         rcu_read_lock();
 162         /*
 163          * XXX: use ieee80211_find_sta! This requires quite a bit of work
 164          * under the current ath9k virtual wiphy implementation as we have
 165          * no way of tying a vif to wiphy. Typically vifs are attached to
 166          * at least one sdata of a wiphy on mac80211 but with ath9k virtual
 167          * wiphy you'd have to iterate over every wiphy and each sdata.
 168          */
 169         sta = ieee80211_find_sta_by_hw(hw, hdr->addr2);
 170         if (sta) {
 171                 an = (struct ath_node *) sta->drv_priv;
 172                 if (rx_stats->rs_rssi != ATH9K_RSSI_BAD &&
 173                    !rx_stats->rs_moreaggr)
 174                         ATH_RSSI_LPF(an->last_rssi, rx_stats->rs_rssi);
 175                 last_rssi = an->last_rssi;
 176         }
 177         rcu_read_unlock();
 178
 179         if (likely(last_rssi != ATH_RSSI_DUMMY_MARKER))
 180                 rx_stats->rs_rssi = ATH_EP_RND(last_rssi,
 181                                               ATH_RSSI_EP_MULTIPLIER);
 182         if (rx_stats->rs_rssi < 0)
 183                 rx_stats->rs_rssi = 0;
 184         else if (rx_stats->rs_rssi > 127)
 185                 rx_stats->rs_rssi = 127;
 186
 187         /* Update Beacon RSSI, this is used by ANI. */
 188         if (ieee80211_is_beacon(fc))
 189                 ah->stats.avgbrssi = rx_stats->rs_rssi;
 190 }
 191
 192 /*
 193  * For Decrypt or Demic errors, we only mark packet status here and always push
 194  * up the frame up to let mac80211 handle the actual error case, be it no
 195  * decryption key or real decryption error. This let us keep statistics there.
 196  */
 197 int ath9k_cmn_rx_skb_preprocess(struct ath_common *common,
 198                                 struct ieee80211_hw *hw,
 199                                 struct sk_buff *skb,
 200                                 struct ath_rx_status *rx_stats,
 201                                 struct ieee80211_rx_status *rx_status,
 202                                 bool *decrypt_error)
 203 {
 204         struct ath_hw *ah = common->ah;
 205
 206         memset(rx_status, 0, sizeof(struct ieee80211_rx_status));
 207         if (!ath9k_rx_accept(common, skb, rx_status, rx_stats, decrypt_error))
 208                 return -EINVAL;
 209
 210         ath9k_process_rssi(common, hw, skb, rx_stats);
 211
 212         rx_status->rate_idx = ath9k_process_rate(common, hw,
 213                                                  rx_stats, rx_status, skb);
 214         rx_status->mactime = ath9k_hw_extend_tsf(ah, rx_stats->rs_tstamp);
 215         rx_status->band = hw->conf.channel->band;
 216         rx_status->freq = hw->conf.channel->center_freq;
 217         rx_status->noise = common->ani.noise_floor;
 218         rx_status->signal = ATH_DEFAULT_NOISE_FLOOR + rx_stats->rs_rssi;
 219         rx_status->antenna = rx_stats->rs_antenna;
 220         rx_status->flag |= RX_FLAG_TSFT;
 221
 222         return 0;
 223 }
 224 EXPORT_SYMBOL(ath9k_cmn_rx_skb_preprocess);
 225
 226 void ath9k_cmn_rx_skb_postprocess(struct ath_common *common,
 227                                   struct sk_buff *skb,
 228                                   struct ath_rx_status *rx_stats,
 229                                   struct ieee80211_rx_status *rxs,
 230                                   bool decrypt_error)
 231 {
 232         struct ath_hw *ah = common->ah;
 233         struct ieee80211_hdr *hdr;
 234         int hdrlen, padsize;
 235         u8 keyix;
 236         __le16 fc;
 237
 238         /* see if any padding is done by the hw and remove it */
 239         hdr = (struct ieee80211_hdr *) skb->data;
 240         hdrlen = ieee80211_get_hdrlen_from_skb(skb);
 241         fc = hdr->frame_control;
 242
 243         /* The MAC header is padded to have 32-bit boundary if the
 244          * packet payload is non-zero. The general calculation for
 245          * padsize would take into account odd header lengths:
 246          * padsize = (4 - hdrlen % 4) % 4; However, since only
 247          * even-length headers are used, padding can only be 0 or 2
 248          * bytes and we can optimize this a bit. In addition, we must
 249          * not try to remove padding from short control frames that do
 250          * not have payload. */
 251         padsize = hdrlen & 3;
 252         if (padsize && hdrlen >= 24) {
 253                 memmove(skb->data + padsize, skb->data, hdrlen);
 254                 skb_pull(skb, padsize);
 255         }
 256
 257         keyix = rx_stats->rs_keyix;
 258
 259         if (!(keyix == ATH9K_RXKEYIX_INVALID) && !decrypt_error) {
 260                 rxs->flag |= RX_FLAG_DECRYPTED;
 261         } else if (ieee80211_has_protected(fc)
 262                    && !decrypt_error && skb->len >= hdrlen + 4) {
 263                 keyix = skb->data[hdrlen + 3] >> 6;
 264
 265                 if (test_bit(keyix, common->keymap))
 266                         rxs->flag |= RX_FLAG_DECRYPTED;
 267         }
 268         if (ah->sw_mgmt_crypto &&
 269             (rxs->flag & RX_FLAG_DECRYPTED) &&
 270             ieee80211_is_mgmt(fc))
 271                 /* Use software decrypt for management frames. */
 272                 rxs->flag &= ~RX_FLAG_DECRYPTED;
 273 }
 274 EXPORT_SYMBOL(ath9k_cmn_rx_skb_postprocess);
 275
 276 static int __init ath9k_cmn_init(void)
 277 {
 278         return 0;
 279 }
 280 module_init(ath9k_cmn_init);
 281
 282 static void __exit ath9k_cmn_exit(void)
 283 {
 284         return;
 285 }
 286 module_exit(ath9k_cmn_exit);