nl80211/mac80211: define and allow configuring mesh element TTL
[linux-2.6.git] / 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 }