openwrt/target/linux/package/ieee80211-dscape/src/ieee80211_scan.c

   1 /*
   2  * Copyright 2002-2004, Instant802 Networks, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/config.h>
  10 #include <linux/version.h>
  11 #include <linux/module.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/types.h>
  14 #include <linux/slab.h>
  15 #include <linux/skbuff.h>
  16
  17 #include <net/ieee80211.h>
  18 #include "ieee80211_i.h"
  19 #include "rate_control.h"
  20
  21
  22 /* Maximum number of seconds to wait for the traffic load to get below
  23  * threshold before forcing a passive scan. */
  24 #define MAX_SCAN_WAIT 60
  25 /* Threshold (pkts/sec TX or RX) for delaying passive scan */
  26 #define SCAN_TXRX_THRESHOLD 75
  27
  28 static void get_channel_params(struct ieee80211_local *local, int channel,
  29                                 struct ieee80211_hw_modes **mode,
  30                                 struct ieee80211_channel **chan)
  31 {
  32         int m;
  33
  34         for (m = 0; m < local->hw->num_modes; m++) {
  35                 *mode = &local->hw->modes[m];
  36                 if ((*mode)->mode == local->conf.phymode)
  37                         break;
  38         }
  39         local->scan.mode_idx = m;
  40         local->scan.chan_idx = 0;
  41         do {
  42                 *chan = &(*mode)->channels[local->scan.chan_idx];
  43                 if ((*chan)->chan == channel) {
  44                         return;
  45                 }
  46                 local->scan.chan_idx++;
  47         } while (local->scan.chan_idx < (*mode)->num_channels);
  48         *chan = NULL;
  49 }
  50
  51
  52 static void next_chan_same_mode(struct ieee80211_local *local,
  53                                 struct ieee80211_hw_modes **mode,
  54                                 struct ieee80211_channel **chan)
  55 {
  56         int m, prev;
  57
  58         for (m = 0; m < local->hw->num_modes; m++) {
  59                 *mode = &local->hw->modes[m];
  60                 if ((*mode)->mode == local->conf.phymode)
  61                         break;
  62         }
  63         local->scan.mode_idx = m;
  64
  65         /* Select next channel - scan only channels marked with W_SCAN flag */
  66         prev = local->scan.chan_idx;
  67         do {
  68                 local->scan.chan_idx++;
  69                 if (local->scan.chan_idx >= (*mode)->num_channels)
  70                         local->scan.chan_idx = 0;
  71                 *chan = &(*mode)->channels[local->scan.chan_idx];
  72                 if ((*chan)->flag & IEEE80211_CHAN_W_SCAN)
  73                         break;
  74         } while (local->scan.chan_idx != prev);
  75 }
  76
  77
  78 static void next_chan_all_modes(struct ieee80211_local *local,
  79                                 struct ieee80211_hw_modes **mode,
  80                                 struct ieee80211_channel **chan)
  81 {
  82         int prev, prev_m;
  83
  84         if (local->scan.mode_idx >= local->hw->num_modes) {
  85                 local->scan.mode_idx = 0;
  86                 local->scan.chan_idx = 0;
  87         }
  88
  89         /* Select next channel - scan only channels marked with W_SCAN flag */
  90         prev = local->scan.chan_idx;
  91         prev_m = local->scan.mode_idx;
  92         do {
  93                 *mode = &local->hw->modes[local->scan.mode_idx];
  94                 local->scan.chan_idx++;
  95                 if (local->scan.chan_idx >= (*mode)->num_channels) {
  96                         local->scan.chan_idx = 0;
  97                         local->scan.mode_idx++;
  98                         if (local->scan.mode_idx >= local->hw->num_modes)
  99                                 local->scan.mode_idx = 0;
 100                         *mode = &local->hw->modes[local->scan.mode_idx];
 101                 }
 102                 *chan = &(*mode)->channels[local->scan.chan_idx];
 103                 if ((*chan)->flag & IEEE80211_CHAN_W_SCAN)
 104                         break;
 105         } while (local->scan.chan_idx != prev ||
 106                  local->scan.mode_idx != prev_m);
 107 }
 108
 109
 110 static void ieee80211_scan_start(struct net_device *dev,
 111                                  struct ieee80211_scan_conf *conf)
 112 {
 113         struct ieee80211_local *local = dev->priv;
 114         int old_mode_idx = local->scan.mode_idx;
 115         int old_chan_idx = local->scan.chan_idx;
 116         struct ieee80211_hw_modes *mode = NULL;
 117         struct ieee80211_channel *chan = NULL;
 118         int ret;
 119
 120         if (local->hw->passive_scan == 0) {
 121                 printk(KERN_DEBUG "%s: Scan handler called, yet the hardware "
 122                        "does not support passive scanning. Disabled.\n",
 123                        dev->name);
 124                 return;
 125         }
 126
 127         if ((local->scan.tries < MAX_SCAN_WAIT &&
 128              local->scan.txrx_count > SCAN_TXRX_THRESHOLD)) {
 129                 local->scan.tries++;
 130                 /* Count TX/RX packets during one second interval and allow
 131                  * scan to start only if the number of packets is below the
 132                  * threshold. */
 133                 local->scan.txrx_count = 0;
 134                 local->scan.timer.expires = jiffies + HZ;
 135                 add_timer(&local->scan.timer);
 136                 return;
 137         }
 138
 139         if (local->scan.skb == NULL) {
 140                 printk(KERN_DEBUG "%s: Scan start called even though scan.skb "
 141                        "is not set\n", dev->name);
 142         }
 143
 144         if (local->scan.our_mode_only) {
 145                 if (local->scan.channel > 0) {
 146                         get_channel_params(local, local->scan.channel, &mode,
 147                                            &chan);
 148                 } else
 149                         next_chan_same_mode(local, &mode, &chan);
 150         }
 151         else
 152                 next_chan_all_modes(local, &mode, &chan);
 153
 154         conf->scan_channel = chan->chan;
 155         conf->scan_freq = chan->freq;
 156         conf->scan_channel_val = chan->val;
 157         conf->scan_phymode = mode->mode;
 158         conf->scan_power_level = chan->power_level;
 159         conf->scan_antenna_max = chan->antenna_max;
 160         conf->scan_time = 2 * local->hw->channel_change_time +
 161                 local->scan.time; /* 10ms scan time+hardware changes */
 162         conf->skb = local->scan.skb ?
 163                 skb_clone(local->scan.skb, GFP_ATOMIC) : NULL;
 164         conf->tx_control = &local->scan.tx_control;
 165 #if 0
 166         printk(KERN_DEBUG "%s: Doing scan on mode: %d freq: %d chan: %d "
 167                "for %d ms\n",
 168                dev->name, conf->scan_phymode, conf->scan_freq,
 169                conf->scan_channel, conf->scan_time);
 170 #endif
 171         local->scan.rx_packets = 0;
 172         local->scan.rx_beacon = 0;
 173         local->scan.freq = chan->freq;
 174         local->scan.in_scan = 1;
 175
 176         ieee80211_netif_oper(dev, NETIF_STOP);
 177
 178         ret = local->hw->passive_scan(dev, IEEE80211_SCAN_START, conf);
 179
 180         if (ret == 0) {
 181                 long usec = local->hw->channel_change_time +
 182                         local->scan.time;
 183                 usec += 1000000L / HZ - 1;
 184                 usec /= 1000000L / HZ;
 185                 local->scan.timer.expires = jiffies + usec;
 186         } else {
 187                 local->scan.in_scan = 0;
 188                 if (conf->skb)
 189                         dev_kfree_skb(conf->skb);
 190                 ieee80211_netif_oper(dev, NETIF_WAKE);
 191                 if (ret == -EAGAIN) {
 192                         local->scan.timer.expires = jiffies +
 193                                 (local->scan.interval * HZ / 100);
 194                         local->scan.mode_idx = old_mode_idx;
 195                         local->scan.chan_idx = old_chan_idx;
 196                 } else {
 197                         printk(KERN_DEBUG "%s: Got unknown error from "
 198                                "passive_scan %d\n", dev->name, ret);
 199                         local->scan.timer.expires = jiffies +
 200                                 (local->scan.interval * HZ);
 201                 }
 202                 local->scan.in_scan = 0;
 203         }
 204
 205         add_timer(&local->scan.timer);
 206 }
 207
 208
 209 static void ieee80211_scan_stop(struct net_device *dev,
 210                                 struct ieee80211_scan_conf *conf)
 211 {
 212         struct ieee80211_local *local = dev->priv;
 213         struct ieee80211_hw_modes *mode;
 214         struct ieee80211_channel *chan;
 215         int wait;
 216
 217         if (local->hw->passive_scan == NULL)
 218                 return;
 219
 220         if (local->scan.mode_idx >= local->hw->num_modes) {
 221                 local->scan.mode_idx = 0;
 222                 local->scan.chan_idx = 0;
 223         }
 224
 225         mode = &local->hw->modes[local->scan.mode_idx];
 226
 227         if (local->scan.chan_idx >= mode->num_channels) {
 228                 local->scan.chan_idx = 0;
 229         }
 230
 231         chan = &mode->channels[local->scan.chan_idx];
 232
 233         local->hw->passive_scan(dev, IEEE80211_SCAN_END, conf);
 234
 235 #ifdef CONFIG_IEEE80211_VERBOSE_DEBUG
 236         printk(KERN_DEBUG "%s: Did scan on mode: %d freq: %d chan: %d "
 237                "GOT: %d Beacon: %d (%d)\n",
 238                dev->name,
 239                mode->mode, chan->freq, chan->chan,
 240                local->scan.rx_packets, local->scan.rx_beacon,
 241                local->scan.tries);
 242 #endif /* CONFIG_IEEE80211_VERBOSE_DEBUG */
 243         local->scan.num_scans++;
 244
 245         local->scan.in_scan = 0;
 246         ieee80211_netif_oper(dev, NETIF_WAKE);
 247
 248         local->scan.tries = 0;
 249         /* Use random interval of scan.interval .. 2 * scan.interval */
 250         wait = (local->scan.interval * HZ * ((net_random() & 127) + 128)) /
 251                 128;
 252         local->scan.timer.expires = jiffies + wait;
 253
 254         add_timer(&local->scan.timer);
 255 }
 256
 257
 258 static void ieee80211_scan_handler(unsigned long uldev)
 259 {
 260         struct net_device *dev = (struct net_device *) uldev;
 261         struct ieee80211_local *local = dev->priv;
 262         struct ieee80211_scan_conf conf;
 263
 264         if (local->scan.interval == 0 && !local->scan.in_scan) {
 265                 /* Passive scanning is disabled - keep the timer always
 266                  * running to make code cleaner. */
 267                 local->scan.timer.expires = jiffies + 10 * HZ;
 268                 add_timer(&local->scan.timer);
 269                 return;
 270         }
 271
 272         memset(&conf, 0, sizeof(struct ieee80211_scan_conf));
 273         conf.running_freq = local->conf.freq;
 274         conf.running_channel = local->conf.channel;
 275         conf.running_phymode = local->conf.phymode;
 276         conf.running_channel_val = local->conf.channel_val;
 277         conf.running_power_level = local->conf.power_level;
 278         conf.running_antenna_max = local->conf.antenna_max;
 279
 280         if (local->scan.in_scan == 0)
 281                 ieee80211_scan_start(dev, &conf);
 282         else
 283                 ieee80211_scan_stop(dev, &conf);
 284 }
 285
 286
 287 void ieee80211_init_scan(struct net_device *dev)
 288 {
 289         struct ieee80211_local *local = dev->priv;
 290         struct ieee80211_hdr hdr;
 291         u16 fc;
 292         int len = 10;
 293         struct rate_control_extra extra;
 294
 295         /* Only initialize passive scanning if the hardware supports it */
 296         if (!local->hw->passive_scan) {
 297                 local->scan.skb = NULL;
 298                 memset(&local->scan.tx_control, 0,
 299                        sizeof(local->scan.tx_control));
 300                 printk(KERN_DEBUG "%s: Does not support passive scan, "
 301                        "disabled\n", dev->name);
 302                 return;
 303         }
 304
 305         local->scan.interval = 0;
 306         local->scan.our_mode_only = 1;
 307         local->scan.time = 10000;
 308         local->scan.timer.function = ieee80211_scan_handler;
 309         local->scan.timer.data = (unsigned long) dev;
 310         local->scan.timer.expires = jiffies + local->scan.interval * HZ;
 311         add_timer(&local->scan.timer);
 312
 313         /* Create a CTS from for broadcasting before
 314          * the low level changes channels */
 315         local->scan.skb = alloc_skb(len, GFP_KERNEL);
 316         if (local->scan.skb == NULL) {
 317                 printk(KERN_WARNING "%s: Failed to allocate CTS packet for "
 318                        "passive scan\n", dev->name);
 319                 return;
 320         }
 321
 322         fc = (WLAN_FC_TYPE_CTRL << 2) | (WLAN_FC_STYPE_CTS << 4);
 323         hdr.frame_control = cpu_to_le16(fc);
 324         hdr.duration_id =
 325                 cpu_to_le16(2 * local->hw->channel_change_time +
 326                             local->scan.time);
 327         memcpy(hdr.addr1, dev->dev_addr, ETH_ALEN); /* DA */
 328         hdr.seq_ctrl = 0;
 329
 330         memcpy(skb_put(local->scan.skb, len), &hdr, len);
 331
 332         memset(&local->scan.tx_control, 0, sizeof(local->scan.tx_control));
 333         local->scan.tx_control.key_idx = HW_KEY_IDX_INVALID;
 334         local->scan.tx_control.do_not_encrypt = 1;
 335         memset(&extra, 0, sizeof(extra));
 336         extra.endidx = local->num_curr_rates;
 337         local->scan.tx_control.tx_rate =
 338                 rate_control_get_rate(dev, local->scan.skb, &extra)->val;
 339         local->scan.tx_control.no_ack = 1;
 340 }
 341
 342
 343 void ieee80211_stop_scan(struct net_device *dev)
 344 {
 345         struct ieee80211_local *local = dev->priv;
 346
 347         if (local->hw->passive_scan != 0) {
 348                 del_timer_sync(&local->scan.timer);
 349                 dev_kfree_skb(local->scan.skb);
 350                 local->scan.skb = NULL;
 351         }
 352 }