2 * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 * $FreeBSD: head/sys/net80211/ieee80211_dfs.c 196785 2009-09-03 16:29:02Z sam $
29 * IEEE 802.11 DFS/Radar support.
34 #include <sys/param.h>
35 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/kernel.h>
40 #include <sys/socket.h>
41 #include <sys/sockio.h>
42 #include <sys/endian.h>
43 #include <sys/errno.h>
45 #include <sys/sysctl.h>
48 #include <net/if_media.h>
49 #include <net/route.h>
51 #include <netproto/802_11/ieee80211_var.h>
53 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
55 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
56 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
57 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
58 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
60 static int ieee80211_cac_timeout = 60; /* 60 seconds */
61 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
62 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
63 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
66 ieee80211_dfs_attach(struct ieee80211com *ic)
68 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
70 callout_init(&dfs->nol_timer);
71 callout_init(&dfs->cac_timer);
75 ieee80211_dfs_detach(struct ieee80211com *ic)
77 /* NB: we assume no locking is needed */
78 ieee80211_dfs_reset(ic);
82 ieee80211_dfs_reset(struct ieee80211com *ic)
84 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
87 /* NB: we assume no locking is needed */
88 /* NB: cac_timer should be cleared by the state machine */
89 callout_stop(&dfs->nol_timer);
90 for (i = 0; i < ic->ic_nchans; i++)
91 ic->ic_channels[i].ic_state = 0;
96 cac_timeout_callout(void *arg)
98 struct ieee80211vap *vap = arg;
99 struct ieee80211com *ic;
100 struct ieee80211_dfs_state *dfs;
103 wlan_serialize_enter();
106 if (vap->iv_state != IEEE80211_S_CAC) { /* NB: just in case */
107 wlan_serialize_exit();
111 * When radar is detected during a CAC we are woken
112 * up prematurely to switch to a new channel.
113 * Check the channel to decide how to act.
115 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
116 ieee80211_notify_cac(ic, ic->ic_curchan,
117 IEEE80211_NOTIFY_CAC_RADAR);
119 if_printf(vap->iv_ifp,
120 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
121 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
123 /* XXX clobbers any existing desired channel */
124 /* NB: dfs->newchan may be NULL, that's ok */
125 vap->iv_des_chan = dfs->newchan;
126 /* XXX recursive lock need ieee80211_new_state_locked */
127 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
129 if_printf(vap->iv_ifp,
130 "CAC timer on channel %u (%u MHz) expired; "
131 "no radar detected\n",
132 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
134 * Mark all channels with the current frequency
135 * as having completed CAC; this keeps us from
136 * doing it again until we change channels.
138 for (i = 0; i < ic->ic_nchans; i++) {
139 struct ieee80211_channel *c = &ic->ic_channels[i];
140 if (c->ic_freq == ic->ic_curchan->ic_freq)
141 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
143 ieee80211_notify_cac(ic, ic->ic_curchan,
144 IEEE80211_NOTIFY_CAC_EXPIRE);
145 ieee80211_cac_completeswitch(vap);
147 wlan_serialize_exit();
151 * Initiate the CAC timer. The driver is responsible
152 * for setting up the hardware to scan for radar on the
153 * channnel, we just handle timing things out.
156 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
158 struct ieee80211com *ic = vap->iv_ic;
159 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
161 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout_callout, vap);
162 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
163 ticks_to_secs(CAC_TIMEOUT),
164 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
165 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
169 * Clear the CAC timer.
172 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
174 struct ieee80211com *ic = vap->iv_ic;
175 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
177 /* NB: racey but not important */
178 if (callout_pending(&dfs->cac_timer)) {
179 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
180 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
181 ieee80211_notify_cac(ic, ic->ic_curchan,
182 IEEE80211_NOTIFY_CAC_STOP);
184 callout_stop(&dfs->cac_timer);
188 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
189 const struct ieee80211_channel *chan)
193 for (i = 0; i < ic->ic_nchans; i++) {
194 struct ieee80211_channel *c = &ic->ic_channels[i];
195 if (c->ic_freq == chan->ic_freq)
196 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
201 dfs_timeout_callout(void *arg)
203 struct ieee80211com *ic = arg;
204 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
205 struct ieee80211_channel *c;
208 wlan_serialize_enter();
209 now = oldest = ticks;
210 for (i = 0; i < ic->ic_nchans; i++) {
211 c = &ic->ic_channels[i];
212 if (IEEE80211_IS_CHAN_RADAR(c)) {
213 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
214 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
215 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
217 * NB: do this here so we get only one
218 * msg instead of one for every channel
221 if_printf(ic->ic_ifp, "radar on channel"
222 " %u (%u MHz) cleared after timeout\n",
223 c->ic_ieee, c->ic_freq);
224 /* notify user space */
226 ~IEEE80211_CHANSTATE_NORADAR;
227 ieee80211_notify_radar(ic, c);
229 } else if (dfs->nol_event[i] < oldest)
230 oldest = dfs->nol_event[i];
234 /* arrange to process next channel up for a status change */
235 callout_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT - now,
236 dfs_timeout_callout, ic);
238 wlan_serialize_exit();
242 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
243 const struct ieee80211_channel *newchan)
246 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
247 curchan->ic_ieee, curchan->ic_freq);
249 if_printf(ifp, "radar detected on channel %u (%u MHz), "
250 "moving to channel %u (%u MHz)\n",
251 curchan->ic_ieee, curchan->ic_freq,
252 newchan->ic_ieee, newchan->ic_freq);
256 * Handle a radar detection event on a channel. The channel is
257 * added to the NOL list and we record the time of the event.
258 * Entries are aged out after NOL_TIMEOUT. If radar was
259 * detected while doing CAC we force a state/channel change.
260 * Otherwise radar triggers a channel switch using the CSA
261 * mechanism (when the channel is the bss channel).
264 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
266 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
270 * Mark all entries with this frequency. Notify user
271 * space and arrange for notification when the radar
272 * indication is cleared. Then kick the NOL processing
273 * thread if not already running.
276 for (i = 0; i < ic->ic_nchans; i++) {
277 struct ieee80211_channel *c = &ic->ic_channels[i];
278 if (c->ic_freq == chan->ic_freq) {
279 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
280 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
281 dfs->nol_event[i] = now;
284 ieee80211_notify_radar(ic, chan);
285 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
286 if (!callout_pending(&dfs->nol_timer)) {
287 callout_reset(&dfs->nol_timer, NOL_TIMEOUT,
288 dfs_timeout_callout, ic);
292 * If radar is detected on the bss channel while
293 * doing CAC; force a state change by scheduling the
294 * callout to be dispatched asap. Otherwise, if this
295 * event is for the bss channel then we must quiet
296 * traffic and schedule a channel switch.
298 * Note this allows us to receive notification about
299 * channels other than the bss channel; not sure
300 * that can/will happen but it's simple to support.
302 if (chan == ic->ic_bsschan) {
303 /* XXX need a way to defer to user app */
304 dfs->newchan = ieee80211_dfs_pickchannel(ic);
306 announce_radar(ic->ic_ifp, chan, dfs->newchan);
309 if (callout_pending(&dfs->cac_timer)) {
310 callout_reset(&dfs->cac_timer, 0,
311 cac_timeout_callout, vap);
313 else if (dfs->newchan != NULL) {
314 /* XXX mode 1, switch count 2 */
315 /* XXX calculate switch count based on max
316 switch time and beacon interval? */
317 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
320 * Spec says to stop all transmissions and
321 * wait on the current channel for an entry
322 * on the NOL to expire.
329 * Issue rate-limited console msgs.
331 if (dfs->lastchan != chan) {
332 dfs->lastchan = chan;
334 announce_radar(ic->ic_ifp, chan, NULL);
335 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
336 announce_radar(ic->ic_ifp, chan, NULL);
341 struct ieee80211_channel *
342 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
344 struct ieee80211_channel *c;
349 * Consult the scan cache first.
351 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
353 * XXX if curchan is HT this will never find a channel
354 * XXX 'cuz we scan only legacy channels
356 c = ieee80211_scan_pickchannel(ic, flags);
360 * No channel found in scan cache; select a compatible
361 * one at random (skipping channels where radar has
364 get_random_bytes(&v, sizeof(v));
366 for (i = v; i < ic->ic_nchans; i++) {
367 c = &ic->ic_channels[i];
368 if (!IEEE80211_IS_CHAN_RADAR(c) &&
369 (c->ic_flags & flags) == flags)
372 for (i = 0; i < v; i++) {
373 c = &ic->ic_channels[i];
374 if (!IEEE80211_IS_CHAN_RADAR(c) &&
375 (c->ic_flags & flags) == flags)
378 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");