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 *
rdev_freq_to_chan(struct cfg80211_registered_device * rdev,int freq,enum nl80211_channel_type channel_type)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
can_beacon_sec_chan(struct wiphy * wiphy,struct ieee80211_channel * chan,enum nl80211_channel_type channel_type)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
cfg80211_set_freq(struct cfg80211_registered_device * rdev,struct wireless_dev * wdev,int freq,enum nl80211_channel_type channel_type)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 }
136