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_fixed_channel(struct cfg80211_registered_device *rdev,
  14                    struct wireless_dev *for_wdev)
  15 {
  16         struct wireless_dev *wdev;
  17         struct ieee80211_channel *result = NULL;
  18
  19         WARN_ON(!mutex_is_locked(&rdev->devlist_mtx));
  20
  21         list_for_each_entry(wdev, &rdev->netdev_list, list) {
  22                 if (wdev == for_wdev)
  23                         continue;
  24
  25                 /*
  26                  * Lock manually to tell lockdep about allowed
  27                  * nesting here if for_wdev->mtx is held already.
  28                  * This is ok as it's all under the rdev devlist
  29                  * mutex and as such can only be done once at any
  30                  * given time.
  31                  */
  32                 mutex_lock_nested(&wdev->mtx, SINGLE_DEPTH_NESTING);
  33                 if (wdev->current_bss)
  34                         result = wdev->current_bss->pub.channel;
  35                 wdev_unlock(wdev);
  36
  37                 if (result)
  38                         break;
  39         }
  40
  41         return result;
  42 }
  43
  44 struct ieee80211_channel *
  45 rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
  46                   int freq, enum nl80211_channel_type channel_type)
  47 {
  48         struct ieee80211_channel *chan;
  49         struct ieee80211_sta_ht_cap *ht_cap;
  50
  51         chan = ieee80211_get_channel(&rdev->wiphy, freq);
  52
  53         /* Primary channel not allowed */
  54         if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)
  55                 return NULL;
  56
  57         if (channel_type == NL80211_CHAN_HT40MINUS &&
  58             chan->flags & IEEE80211_CHAN_NO_HT40MINUS)
  59                 return NULL;
  60         else if (channel_type == NL80211_CHAN_HT40PLUS &&
  61                  chan->flags & IEEE80211_CHAN_NO_HT40PLUS)
  62                 return NULL;
  63
  64         ht_cap = &rdev->wiphy.bands[chan->band]->ht_cap;
  65
  66         if (channel_type != NL80211_CHAN_NO_HT) {
  67                 if (!ht_cap->ht_supported)
  68                         return NULL;
  69
  70                 if (!(ht_cap->cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) ||
  71                     ht_cap->cap & IEEE80211_HT_CAP_40MHZ_INTOLERANT)
  72                         return NULL;
  73         }
  74
  75         return chan;
  76 }
  77
  78 int rdev_set_freq(struct cfg80211_registered_device *rdev,
  79                   struct wireless_dev *for_wdev,
  80                   int freq, enum nl80211_channel_type channel_type)
  81 {
  82         struct ieee80211_channel *chan;
  83         int result;
  84
  85         if (rdev_fixed_channel(rdev, for_wdev))
  86                 return -EBUSY;
  87
  88         if (!rdev->ops->set_channel)
  89                 return -EOPNOTSUPP;
  90
  91         chan = rdev_freq_to_chan(rdev, freq, channel_type);
  92         if (!chan)
  93                 return -EINVAL;
  94
  95         result = rdev->ops->set_channel(&rdev->wiphy, chan, channel_type);
  96         if (result)
  97                 return result;
  98
  99         rdev->channel = chan;
 100
 101         return 0;
 102 }