net/wireless/chan.c

   1 /*
   2  * This file contains helper code to handle channel
   3  * settings and keeping track of what is possible at
   4  * any point in time.
   5  *
   6  * Copyright 2009       Johannes Berg <johannes@sipsolutions.net>
   7  */
   8
   9 #include <net/cfg80211.h>
  10 #include "core.h"
  11
  12 struct ieee80211_channel *
  13 rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
  14                   int freq, enum nl80211_channel_type channel_type)
  15 {
  16         struct ieee80211_channel *chan;
  17         struct ieee80211_sta_ht_cap *ht_cap;
  18
  19         chan = ieee80211_get_channel(&rdev->wiphy, freq);
  20
  21         /* Primary channel not allowed */
  22         if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)
  23                 return NULL;
  24
  25         if (channel_type == NL80211_CHAN_HT40MINUS &&
  26             chan->flags & IEEE80211_CHAN_NO_HT40MINUS)
  27                 return NULL;
  28         else if (channel_type == NL80211_CHAN_HT40PLUS &&
  29                  chan->flags & IEEE80211_CHAN_NO_HT40PLUS)
  30                 return NULL;
  31
  32         ht_cap = &rdev->wiphy.bands[chan->band]->ht_cap;
  33
  34         if (channel_type != NL80211_CHAN_NO_HT) {
  35                 if (!ht_cap->ht_supported)
  36                         return NULL;
  37
  38                 if (channel_type != NL80211_CHAN_HT20 &&
  39                     (!(ht_cap->cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) ||
  40                     ht_cap->cap & IEEE80211_HT_CAP_40MHZ_INTOLERANT))
  41                         return NULL;
  42         }
  43
  44         return chan;
  45 }
  46
  47 static bool can_beacon_sec_chan(struct wiphy *wiphy,
  48                                 struct ieee80211_channel *chan,
  49                                 enum nl80211_channel_type channel_type)
  50 {
  51         struct ieee80211_channel *sec_chan;
  52         int diff;
  53
  54         switch (channel_type) {
  55         case NL80211_CHAN_HT40PLUS:
  56                 diff = 20;
  57         case NL80211_CHAN_HT40MINUS:
  58                 diff = -20;
  59         default:
  60                 return false;
  61         }
  62
  63         sec_chan = ieee80211_get_channel(wiphy, chan->center_freq + diff);
  64         if (!sec_chan)
  65                 return false;
  66
  67         /* we'll need a DFS capability later */
  68         if (sec_chan->flags & (IEEE80211_CHAN_DISABLED |
  69                                IEEE80211_CHAN_PASSIVE_SCAN |
  70                                IEEE80211_CHAN_NO_IBSS |
  71                                IEEE80211_CHAN_RADAR))
  72                 return false;
  73
  74         return true;
  75 }
  76
  77 int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
  78                       struct wireless_dev *wdev, int freq,
  79                       enum nl80211_channel_type channel_type)
  80 {
  81         struct ieee80211_channel *chan;
  82         int result;
  83
  84         if (wdev && wdev->iftype == NL80211_IFTYPE_MONITOR)
  85                 wdev = NULL;
  86
  87         if (wdev) {
  88                 ASSERT_WDEV_LOCK(wdev);
  89
  90                 if (!netif_running(wdev->netdev))
  91                         return -ENETDOWN;
  92         }
  93
  94         if (!rdev->ops->set_channel)
  95                 return -EOPNOTSUPP;
  96
  97         chan = rdev_freq_to_chan(rdev, freq, channel_type);
  98         if (!chan)
  99                 return -EINVAL;
 100
 101         /* Both channels should be able to initiate communication */
 102         if (wdev && (wdev->iftype == NL80211_IFTYPE_ADHOC ||
 103                      wdev->iftype == NL80211_IFTYPE_AP ||
 104                      wdev->iftype == NL80211_IFTYPE_AP_VLAN ||
 105                      wdev->iftype == NL80211_IFTYPE_MESH_POINT ||
 106                      wdev->iftype == NL80211_IFTYPE_P2P_GO)) {
 107                 switch (channel_type) {
 108                 case NL80211_CHAN_HT40PLUS:
 109                 case NL80211_CHAN_HT40MINUS:
 110                         if (!can_beacon_sec_chan(&rdev->wiphy, chan,
 111                                                  channel_type)) {
 112                                 printk(KERN_DEBUG
 113                                        "cfg80211: Secondary channel not "
 114                                        "allowed to initiate communication\n");
 115                                 return -EINVAL;
 116                         }
 117                         break;
 118                 default:
 119                         break;
 120                 }
 121         }
 122
 123         result = rdev->ops->set_channel(&rdev->wiphy,
 124                                         wdev ? wdev->netdev : NULL,
 125                                         chan, channel_type);
 126         if (result)
 127                 return result;
 128
 129         if (wdev)
 130                 wdev->channel = chan;
 131
 132         return 0;
 133 }