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 <linux/export.h>
  10 #include <net/cfg80211.h>
  11 #include "core.h"
  12
  13 struct ieee80211_channel *
  14 rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
  15                   int freq, enum nl80211_channel_type channel_type)
  16 {
  17         struct ieee80211_channel *chan;
  18         struct ieee80211_sta_ht_cap *ht_cap;
  19
  20         chan = ieee80211_get_channel(&rdev->wiphy, freq);
  21
  22         /* Primary channel not allowed */
  23         if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)
  24                 return NULL;
  25
  26         if (channel_type == NL80211_CHAN_HT40MINUS &&
  27             chan->flags & IEEE80211_CHAN_NO_HT40MINUS)
  28                 return NULL;
  29         else if (channel_type == NL80211_CHAN_HT40PLUS &&
  30                  chan->flags & IEEE80211_CHAN_NO_HT40PLUS)
  31                 return NULL;
  32
  33         ht_cap = &rdev->wiphy.bands[chan->band]->ht_cap;
  34
  35         if (channel_type != NL80211_CHAN_NO_HT) {
  36                 if (!ht_cap->ht_supported)
  37                         return NULL;
  38
  39                 if (channel_type != NL80211_CHAN_HT20 &&
  40                     (!(ht_cap->cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) ||
  41                     ht_cap->cap & IEEE80211_HT_CAP_40MHZ_INTOLERANT))
  42                         return NULL;
  43         }
  44
  45         return chan;
  46 }
  47
  48 int cfg80211_can_beacon_sec_chan(struct wiphy *wiphy,
  49                                   struct ieee80211_channel *chan,
  50                                   enum nl80211_channel_type channel_type)
  51 {
  52         struct ieee80211_channel *sec_chan;
  53         int diff;
  54
  55         switch (channel_type) {
  56         case NL80211_CHAN_HT40PLUS:
  57                 diff = 20;
  58                 break;
  59         case NL80211_CHAN_HT40MINUS:
  60                 diff = -20;
  61                 break;
  62         default:
  63                 return false;
  64         }
  65
  66         sec_chan = ieee80211_get_channel(wiphy, chan->center_freq + diff);
  67         if (!sec_chan)
  68                 return false;
  69
  70         /* we'll need a DFS capability later */
  71         if (sec_chan->flags & (IEEE80211_CHAN_DISABLED |
  72                                IEEE80211_CHAN_PASSIVE_SCAN |
  73                                IEEE80211_CHAN_NO_IBSS |
  74                                IEEE80211_CHAN_RADAR))
  75                 return false;
  76
  77         return true;
  78 }
  79 EXPORT_SYMBOL(cfg80211_can_beacon_sec_chan);
  80
  81 int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
  82                       struct wireless_dev *wdev, int freq,
  83                       enum nl80211_channel_type channel_type)
  84 {
  85         struct ieee80211_channel *chan;
  86         int result;
  87         struct wireless_dev *mon_dev = NULL;
  88
  89         if (wdev && wdev->iftype == NL80211_IFTYPE_MONITOR) {
  90                 mon_dev = wdev;
  91                 wdev = NULL;
  92         }
  93
  94         if (wdev) {
  95                 ASSERT_WDEV_LOCK(wdev);
  96
  97                 if (!netif_running(wdev->netdev))
  98                         return -ENETDOWN;
  99         }
 100
 101         if (!rdev->ops->set_channel)
 102                 return -EOPNOTSUPP;
 103
 104         chan = rdev_freq_to_chan(rdev, freq, channel_type);
 105         if (!chan)
 106                 return -EINVAL;
 107
 108         /* Both channels should be able to initiate communication */
 109         if (wdev && (wdev->iftype == NL80211_IFTYPE_ADHOC ||
 110                      wdev->iftype == NL80211_IFTYPE_AP ||
 111                      wdev->iftype == NL80211_IFTYPE_AP_VLAN ||
 112                      wdev->iftype == NL80211_IFTYPE_MESH_POINT ||
 113                      wdev->iftype == NL80211_IFTYPE_P2P_GO)) {
 114                 switch (channel_type) {
 115                 case NL80211_CHAN_HT40PLUS:
 116                 case NL80211_CHAN_HT40MINUS:
 117                         if (!cfg80211_can_beacon_sec_chan(&rdev->wiphy, chan,
 118                                                           channel_type)) {
 119                                 printk(KERN_DEBUG
 120                                        "cfg80211: Secondary channel not "
 121                                        "allowed to initiate communication\n");
 122                                 return -EINVAL;
 123                         }
 124                         break;
 125                 default:
 126                         break;
 127                 }
 128         }
 129
 130         result = rdev->ops->set_channel(&rdev->wiphy,
 131                                         wdev ? wdev->netdev : NULL,
 132                                         chan, channel_type);
 133         if (result)
 134                 return result;
 135
 136         if (wdev)
 137                 wdev->channel = chan;
 138
 139         if (mon_dev)
 140                 mon_dev->channel = chan;
 141
 142         return 0;
 143 }