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                 break;
  58         case NL80211_CHAN_HT40MINUS:
  59                 diff = -20;
  60                 break;
  61         default:
  62                 return false;
  63         }
  64
  65         sec_chan = ieee80211_get_channel(wiphy, chan->center_freq + diff);
  66         if (!sec_chan)
  67                 return false;
  68
  69         /* we'll need a DFS capability later */
  70         if (sec_chan->flags & (IEEE80211_CHAN_DISABLED |
  71                                IEEE80211_CHAN_PASSIVE_SCAN |
  72                                IEEE80211_CHAN_NO_IBSS |
  73                                IEEE80211_CHAN_RADAR))
  74                 return false;
  75
  76         return true;
  77 }
  78
  79 int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
  80                       struct wireless_dev *wdev, int freq,
  81                       enum nl80211_channel_type channel_type)
  82 {
  83         struct ieee80211_channel *chan;
  84         int result;
  85
  86         if (wdev && wdev->iftype == NL80211_IFTYPE_MONITOR)
  87                 wdev = NULL;
  88
  89         if (wdev) {
  90                 ASSERT_WDEV_LOCK(wdev);
  91
  92                 if (!netif_running(wdev->netdev))
  93                         return -ENETDOWN;
  94         }
  95
  96         if (!rdev->ops->set_channel)
  97                 return -EOPNOTSUPP;
  98
  99         chan = rdev_freq_to_chan(rdev, freq, channel_type);
 100         if (!chan)
 101                 return -EINVAL;
 102
 103         /* Both channels should be able to initiate communication */
 104         if (wdev && (wdev->iftype == NL80211_IFTYPE_ADHOC ||
 105                      wdev->iftype == NL80211_IFTYPE_AP ||
 106                      wdev->iftype == NL80211_IFTYPE_AP_VLAN ||
 107                      wdev->iftype == NL80211_IFTYPE_MESH_POINT ||
 108                      wdev->iftype == NL80211_IFTYPE_P2P_GO)) {
 109                 switch (channel_type) {
 110                 case NL80211_CHAN_HT40PLUS:
 111                 case NL80211_CHAN_HT40MINUS:
 112                         if (!can_beacon_sec_chan(&rdev->wiphy, chan,
 113                                                  channel_type)) {
 114                                 printk(KERN_DEBUG
 115                                        "cfg80211: Secondary channel not "
 116                                        "allowed to initiate communication\n");
 117                                 return -EINVAL;
 118                         }
 119                         break;
 120                 default:
 121                         break;
 122                 }
 123         }
 124
 125         result = rdev->ops->set_channel(&rdev->wiphy,
 126                                         wdev ? wdev->netdev : NULL,
 127                                         chan, channel_type);
 128         if (result)
 129                 return result;
 130
 131         if (wdev)
 132                 wdev->channel = chan;
 133
 134         return 0;
 135 }