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.
26 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
32 * IEEE 802.11 DFS/Radar support.
37 #include <sys/param.h>
38 #include <sys/systm.h>
40 #include <sys/malloc.h>
41 #include <sys/kernel.h>
43 #include <sys/socket.h>
44 #include <sys/sockio.h>
45 #include <sys/endian.h>
46 #include <sys/errno.h>
48 #include <sys/sysctl.h>
51 #include <net/if_media.h>
53 #include <net80211/ieee80211_var.h>
55 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
57 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
58 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
59 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
60 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
62 static int ieee80211_cac_timeout = 60; /* 60 seconds */
63 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
64 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
65 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
68 ieee80211_dfs_attach(struct ieee80211com *ic)
70 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
72 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
73 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
77 ieee80211_dfs_detach(struct ieee80211com *ic)
79 /* NB: we assume no locking is needed */
80 ieee80211_dfs_reset(ic);
84 ieee80211_dfs_reset(struct ieee80211com *ic)
86 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
89 /* NB: we assume no locking is needed */
90 /* NB: cac_timer should be cleared by the state machine */
91 callout_drain(&dfs->nol_timer);
92 for (i = 0; i < ic->ic_nchans; i++)
93 ic->ic_channels[i].ic_state = 0;
98 cac_timeout(void *arg)
100 struct ieee80211vap *vap = arg;
101 struct ieee80211com *ic = vap->iv_ic;
102 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
105 IEEE80211_LOCK_ASSERT(ic);
107 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
110 * When radar is detected during a CAC we are woken
111 * up prematurely to switch to a new channel.
112 * Check the channel to decide how to act.
114 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
115 ieee80211_notify_cac(ic, ic->ic_curchan,
116 IEEE80211_NOTIFY_CAC_RADAR);
118 if_printf(vap->iv_ifp,
119 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
120 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
122 /* XXX clobbers any existing desired channel */
123 /* NB: dfs->newchan may be NULL, that's ok */
124 vap->iv_des_chan = dfs->newchan;
125 /* XXX recursive lock need ieee80211_new_state_locked */
126 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
128 if_printf(vap->iv_ifp,
129 "CAC timer on channel %u (%u MHz) expired; "
130 "no radar detected\n",
131 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
133 * Mark all channels with the current frequency
134 * as having completed CAC; this keeps us from
135 * doing it again until we change channels.
137 for (i = 0; i < ic->ic_nchans; i++) {
138 struct ieee80211_channel *c = &ic->ic_channels[i];
139 if (c->ic_freq == ic->ic_curchan->ic_freq)
140 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
142 ieee80211_notify_cac(ic, ic->ic_curchan,
143 IEEE80211_NOTIFY_CAC_EXPIRE);
144 ieee80211_cac_completeswitch(vap);
149 * Initiate the CAC timer. The driver is responsible
150 * for setting up the hardware to scan for radar on the
151 * channnel, we just handle timing things out.
154 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
156 struct ieee80211com *ic = vap->iv_ic;
157 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
159 IEEE80211_LOCK_ASSERT(ic);
161 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, 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 IEEE80211_LOCK_ASSERT(ic);
179 /* NB: racey but not important */
180 if (callout_pending(&dfs->cac_timer)) {
181 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
182 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
183 ieee80211_notify_cac(ic, ic->ic_curchan,
184 IEEE80211_NOTIFY_CAC_STOP);
186 callout_stop(&dfs->cac_timer);
190 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
191 const struct ieee80211_channel *chan)
195 for (i = 0; i < ic->ic_nchans; i++) {
196 struct ieee80211_channel *c = &ic->ic_channels[i];
197 if (c->ic_freq == chan->ic_freq)
198 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
203 dfs_timeout(void *arg)
205 struct ieee80211com *ic = arg;
206 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
207 struct ieee80211_channel *c;
210 IEEE80211_LOCK_ASSERT(ic);
212 now = oldest = ticks;
213 for (i = 0; i < ic->ic_nchans; i++) {
214 c = &ic->ic_channels[i];
215 if (IEEE80211_IS_CHAN_RADAR(c)) {
216 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
217 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
218 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
220 * NB: do this here so we get only one
221 * msg instead of one for every channel
224 if_printf(ic->ic_ifp, "radar on channel"
225 " %u (%u MHz) cleared after timeout\n",
226 c->ic_ieee, c->ic_freq);
227 /* notify user space */
229 ~IEEE80211_CHANSTATE_NORADAR;
230 ieee80211_notify_radar(ic, c);
232 } else if (dfs->nol_event[i] < oldest)
233 oldest = dfs->nol_event[i];
237 /* arrange to process next channel up for a status change */
238 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
243 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
244 const struct ieee80211_channel *newchan)
247 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
248 curchan->ic_ieee, curchan->ic_freq);
250 if_printf(ifp, "radar detected on channel %u (%u MHz), "
251 "moving to channel %u (%u MHz)\n",
252 curchan->ic_ieee, curchan->ic_freq,
253 newchan->ic_ieee, newchan->ic_freq);
257 * Handle a radar detection event on a channel. The channel is
258 * added to the NOL list and we record the time of the event.
259 * Entries are aged out after NOL_TIMEOUT. If radar was
260 * detected while doing CAC we force a state/channel change.
261 * Otherwise radar triggers a channel switch using the CSA
262 * mechanism (when the channel is the bss channel).
265 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
267 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
270 IEEE80211_LOCK_ASSERT(ic);
273 * Mark all entries with this frequency. Notify user
274 * space and arrange for notification when the radar
275 * indication is cleared. Then kick the NOL processing
276 * thread if not already running.
279 for (i = 0; i < ic->ic_nchans; i++) {
280 struct ieee80211_channel *c = &ic->ic_channels[i];
281 if (c->ic_freq == chan->ic_freq) {
282 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
283 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
284 dfs->nol_event[i] = now;
287 ieee80211_notify_radar(ic, chan);
288 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
289 if (!callout_pending(&dfs->nol_timer))
290 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic);
293 * If radar is detected on the bss channel while
294 * doing CAC; force a state change by scheduling the
295 * callout to be dispatched asap. Otherwise, if this
296 * event is for the bss channel then we must quiet
297 * traffic and schedule a channel switch.
299 * Note this allows us to receive notification about
300 * channels other than the bss channel; not sure
301 * that can/will happen but it's simple to support.
303 if (chan == ic->ic_bsschan) {
304 /* XXX need a way to defer to user app */
305 dfs->newchan = ieee80211_dfs_pickchannel(ic);
307 announce_radar(ic->ic_ifp, chan, dfs->newchan);
309 if (callout_pending(&dfs->cac_timer))
310 callout_schedule(&dfs->cac_timer, 0);
311 else if (dfs->newchan != NULL) {
312 /* XXX mode 1, switch count 2 */
313 /* XXX calculate switch count based on max
314 switch time and beacon interval? */
315 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
318 * Spec says to stop all transmissions and
319 * wait on the current channel for an entry
320 * on the NOL to expire.
323 if_printf(ic->ic_ifp, "%s: No free channels; waiting for entry "
324 "on NOL to expire\n", __func__);
328 * Issue rate-limited console msgs.
330 if (dfs->lastchan != chan) {
331 dfs->lastchan = chan;
333 announce_radar(ic->ic_ifp, chan, NULL);
334 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
335 announce_radar(ic->ic_ifp, chan, NULL);
340 struct ieee80211_channel *
341 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
343 struct ieee80211_channel *c;
348 * Consult the scan cache first.
350 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
352 * XXX if curchan is HT this will never find a channel
353 * XXX 'cuz we scan only legacy channels
355 c = ieee80211_scan_pickchannel(ic, flags);
359 * No channel found in scan cache; select a compatible
360 * one at random (skipping channels where radar has
363 get_random_bytes(&v, sizeof(v));
365 for (i = v; i < ic->ic_nchans; i++) {
366 c = &ic->ic_channels[i];
367 if (!IEEE80211_IS_CHAN_RADAR(c) &&
368 (c->ic_flags & flags) == flags)
371 for (i = 0; i < v; i++) {
372 c = &ic->ic_channels[i];
373 if (!IEEE80211_IS_CHAN_RADAR(c) &&
374 (c->ic_flags & flags) == flags)
377 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");