recipes-connectivity/hostapd/files/patches/901-master-zero-wait_dfs.patch

diff --git a/hostapd/config_file.c b/hostapd/config_file.c
index 1e1b685..8f6281a 100644
--- a/hostapd/config_file.c
+++ b/hostapd/config_file.c
@@ -2476,6 +2476,8 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 		conf->ieee80211d = atoi(pos);
 	} else if (os_strcmp(buf, "ieee80211h") == 0) {
 		conf->ieee80211h = atoi(pos);
+	} else if (os_strcmp(buf, "radar_offchan") == 0) {
+		conf->radar_offchan = atoi(pos);
 	} else if (os_strcmp(buf, "ieee8021x") == 0) {
 		bss->ieee802_1x = atoi(pos);
 	} else if (os_strcmp(buf, "eapol_version") == 0) {
diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf
index a89ce9b..0c951a9 100644
--- a/hostapd/hostapd.conf
+++ b/hostapd/hostapd.conf
@@ -143,6 +143,13 @@ ssid=test
 # ieee80211d=1 and local_pwr_constraint configured.
 #spectrum_mgmt_required=1
 
+# Enable radar/CAC detection through a dedicated offchannel chain available on
+# some hw. The chain can't be used to transmits or receives frames.
+# This feature allows to avoid CAC downtime switching on a different channel
+# during CAC detection on the selected radar channel.
+# (default: 0 = disabled, 1 = enabled)
+#radar_offchan=0
+
 # Operation mode (a = IEEE 802.11a (5 GHz), b = IEEE 802.11b (2.4 GHz),
 # g = IEEE 802.11g (2.4 GHz), ad = IEEE 802.11ad (60 GHz); a/g options are used
 # with IEEE 802.11n (HT), too, to specify band). For IEEE 802.11ac (VHT), this
diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h
index 28b7efe..ffc3c2c 100644
--- a/src/ap/ap_config.h
+++ b/src/ap/ap_config.h
@@ -993,6 +993,7 @@ struct hostapd_config {
 	int ieee80211d;
 
 	int ieee80211h; /* DFS */
+	int radar_offchan;
 
 	/*
 	 * Local power constraint is an octet encoded as an unsigned integer in
diff --git a/src/ap/ap_drv_ops.c b/src/ap/ap_drv_ops.c
index bc49079..c97ee39 100644
--- a/src/ap/ap_drv_ops.c
+++ b/src/ap/ap_drv_ops.c
@@ -810,7 +810,8 @@ int hostapd_start_dfs_cac(struct hostapd_iface *iface,
 			  int channel, int ht_enabled, int vht_enabled,
 			  int he_enabled,
 			  int sec_channel_offset, int oper_chwidth,
-			  int center_segment0, int center_segment1)
+			  int center_segment0, int center_segment1,
+			  int radar_offchan)
 {
 	struct hostapd_data *hapd = iface->bss[0];
 	struct hostapd_freq_params data;
@@ -836,10 +837,14 @@ int hostapd_start_dfs_cac(struct hostapd_iface *iface,
 		wpa_printf(MSG_ERROR, "Can't set freq params");
 		return -1;
 	}
+	data.radar_offchan = radar_offchan;
 
 	res = hapd->driver->start_dfs_cac(hapd->drv_priv, &data);
 	if (!res) {
-		iface->cac_started = 1;
+		if (radar_offchan)
+			iface->radar_offchan.cac_started = 1;
+		else
+			iface->cac_started = 1;
 		os_get_reltime(&iface->dfs_cac_start);
 	}
 
diff --git a/src/ap/ap_drv_ops.h b/src/ap/ap_drv_ops.h
index 61c8f64..92842a1 100644
--- a/src/ap/ap_drv_ops.h
+++ b/src/ap/ap_drv_ops.h
@@ -130,7 +130,8 @@ int hostapd_start_dfs_cac(struct hostapd_iface *iface,
 			  int channel, int ht_enabled, int vht_enabled,
 			  int he_enabled,
 			  int sec_channel_offset, int oper_chwidth,
-			  int center_segment0, int center_segment1);
+			  int center_segment0, int center_segment1,
+			  int radar_offchan);
 int hostapd_drv_do_acs(struct hostapd_data *hapd);
 int hostapd_drv_update_dh_ie(struct hostapd_data *hapd, const u8 *peer,
 			     u16 reason_code, const u8 *ie, size_t ielen);
diff --git a/src/ap/dfs.c b/src/ap/dfs.c
index eccda1a..3b1276f 100644
--- a/src/ap/dfs.c
+++ b/src/ap/dfs.c
@@ -51,16 +51,31 @@ static int dfs_get_used_n_chans(struct hostapd_iface *iface, int *seg1)
 	return n_chans;
 }
 
-
+/*
+ * flags:
+ * - 0: any channel
+ * - 1: non-radar channel or radar available one
+ * - 2: radar-only channel not yet available
+ */
 static int dfs_channel_available(struct hostapd_channel_data *chan,
-				 int skip_radar)
+				 int flags)
 {
+	if (flags == 2) {
+		/* Select only radar channel where CAC has not been
+		 * performed yet
+		 */
+		if ((chan->flag & HOSTAPD_CHAN_RADAR) &&
+		    (chan->flag & HOSTAPD_CHAN_DFS_MASK) ==
+		     HOSTAPD_CHAN_DFS_USABLE)
+			return 1;
+		return 0;
+	}
 	/*
 	 * When radar detection happens, CSA is performed. However, there's no
 	 * time for CAC, so radar channels must be skipped when finding a new
 	 * channel for CSA, unless they are available for immediate use.
 	 */
-	if (skip_radar && (chan->flag & HOSTAPD_CHAN_RADAR) &&
+	if (flags && (chan->flag & HOSTAPD_CHAN_RADAR) &&
 	    ((chan->flag & HOSTAPD_CHAN_DFS_MASK) !=
 	     HOSTAPD_CHAN_DFS_AVAILABLE))
 		return 0;
@@ -136,10 +151,15 @@ dfs_get_chan_data(struct hostapd_hw_modes *mode, int freq, int first_chan_idx)
 	return NULL;
 }
 
-
+/*
+ * flags:
+ * - 0: any channel
+ * - 1: non-radar channel or radar available one
+ * - 2: radar-only channel not yet available
+ */
 static int dfs_chan_range_available(struct hostapd_hw_modes *mode,
 				    int first_chan_idx, int num_chans,
-				    int skip_radar)
+				    int flags)
 {
 	struct hostapd_channel_data *first_chan, *chan;
 	int i;
@@ -178,7 +198,7 @@ static int dfs_chan_range_available(struct hostapd_hw_modes *mode,
 			return 0;
 		}
 
-		if (!dfs_channel_available(chan, skip_radar)) {
+		if (!dfs_channel_available(chan, flags)) {
 			wpa_printf(MSG_DEBUG, "DFS: channel not available %d",
 				   first_chan->freq + i * 20);
 			return 0;
@@ -205,10 +225,15 @@ static int is_in_chanlist(struct hostapd_iface *iface,
  *  - hapd->secondary_channel
  *  - hapd->vht/he_oper_centr_freq_seg0_idx
  *  - hapd->vht/he_oper_centr_freq_seg1_idx
+ *
+ * flags:
+ * - 0: any channel
+ * - 1: non-radar channel or radar available one
+ * - 2: radar-only channel not yet available
  */
 static int dfs_find_channel(struct hostapd_iface *iface,
 			    struct hostapd_channel_data **ret_chan,
-			    int idx, int skip_radar)
+			    int idx, int flags)
 {
 	struct hostapd_hw_modes *mode;
 	struct hostapd_channel_data *chan;
@@ -233,7 +258,7 @@ static int dfs_find_channel(struct hostapd_iface *iface,
 		}
 
 		/* Skip incompatible chandefs */
-		if (!dfs_chan_range_available(mode, i, n_chans, skip_radar)) {
+		if (!dfs_chan_range_available(mode, i, n_chans, flags)) {
 			wpa_printf(MSG_DEBUG,
 				   "DFS: range not available for %d (%d)",
 				   chan->freq, chan->chan);
@@ -467,13 +492,18 @@ static int dfs_check_chans_unavailable(struct hostapd_iface *iface,
 	return res;
 }
 
-
+/*
+ * flags:
+ * - 0: any channel
+ * - 1: non-radar channel or radar available one
+ * - 2: radar-only channel not yet available
+ */
 static struct hostapd_channel_data *
 dfs_get_valid_channel(struct hostapd_iface *iface,
 		      int *secondary_channel,
 		      u8 *oper_centr_freq_seg0_idx,
 		      u8 *oper_centr_freq_seg1_idx,
-		      int skip_radar)
+		      int flags)
 {
 	struct hostapd_hw_modes *mode;
 	struct hostapd_channel_data *chan = NULL;
@@ -502,7 +532,7 @@ dfs_get_valid_channel(struct hostapd_iface *iface,
 		return NULL;
 
 	/* Get the count first */
-	num_available_chandefs = dfs_find_channel(iface, NULL, 0, skip_radar);
+	num_available_chandefs = dfs_find_channel(iface, NULL, 0, flags);
 	wpa_printf(MSG_DEBUG, "DFS: num_available_chandefs=%d",
 		   num_available_chandefs);
 	if (num_available_chandefs == 0)
@@ -523,7 +553,7 @@ dfs_get_valid_channel(struct hostapd_iface *iface,
 		return NULL;
 
 	chan_idx = _rand % num_available_chandefs;
-	dfs_find_channel(iface, &chan, chan_idx, skip_radar);
+	dfs_find_channel(iface, &chan, chan_idx, flags);
 	if (!chan) {
 		wpa_printf(MSG_DEBUG, "DFS: no random channel found");
 		return NULL;
@@ -552,7 +582,7 @@ dfs_get_valid_channel(struct hostapd_iface *iface,
 		for (i = 0; i < num_available_chandefs - 1; i++) {
 			/* start from chan_idx + 1, end when chan_idx - 1 */
 			chan_idx2 = (chan_idx + 1 + i) % num_available_chandefs;
-			dfs_find_channel(iface, &chan2, chan_idx2, skip_radar);
+			dfs_find_channel(iface, &chan2, chan_idx2, flags);
 			if (chan2 && abs(chan2->chan - chan->chan) > 12) {
 				/* two channels are not adjacent */
 				sec_chan_idx_80p80 = chan2->chan;
@@ -582,6 +612,27 @@ dfs_get_valid_channel(struct hostapd_iface *iface,
 	return chan;
 }
 
+static int dfs_set_valid_channel(struct hostapd_iface *iface, int skip_radar)
+{
+	struct hostapd_channel_data *channel;
+	u8 cf1 = 0, cf2 = 0;
+	int sec = 0;
+
+	channel = dfs_get_valid_channel(iface, &sec, &cf1, &cf2,
+					skip_radar);
+	if (!channel) {
+		wpa_printf(MSG_ERROR, "could not get valid channel");
+		return -1;
+	}
+
+	iface->freq = channel->freq;
+	iface->conf->channel = channel->chan;
+	iface->conf->secondary_channel = sec;
+	hostapd_set_oper_centr_freq_seg0_idx(iface->conf, cf1);
+	hostapd_set_oper_centr_freq_seg1_idx(iface->conf, cf2);
+
+	return 0;
+}
 
 static int set_dfs_state_freq(struct hostapd_iface *iface, int freq, u32 state)
 {
@@ -761,6 +812,11 @@ static unsigned int dfs_get_cac_time(struct hostapd_iface *iface,
 	return cac_time_ms;
 }
 
+static int hostapd_is_radar_offchan_enabled(struct hostapd_iface *iface)
+{
+	return (iface->drv_flags2 & WPA_DRIVER_RADAR_OFFCHAN) &&
+	       iface->conf->radar_offchan;
+}
 
 /*
  * Main DFS handler
@@ -770,9 +826,8 @@ static unsigned int dfs_get_cac_time(struct hostapd_iface *iface,
  */
 int hostapd_handle_dfs(struct hostapd_iface *iface)
 {
-	struct hostapd_channel_data *channel;
 	int res, n_chans, n_chans1, start_chan_idx, start_chan_idx1;
-	int skip_radar = 0;
+	int skip_radar = 0, radar_offchan;
 
 	if (is_6ghz_freq(iface->freq))
 		return 1;
@@ -825,28 +880,18 @@ int hostapd_handle_dfs(struct hostapd_iface *iface)
 		wpa_printf(MSG_DEBUG, "DFS %d chans unavailable - choose other channel: %s",
 			   res, res ? "yes": "no");
 		if (res) {
-			int sec = 0;
-			u8 cf1 = 0, cf2 = 0;
-
-			channel = dfs_get_valid_channel(iface, &sec, &cf1, &cf2,
-							skip_radar);
-			if (!channel) {
-				wpa_printf(MSG_ERROR, "could not get valid channel");
+			if (dfs_set_valid_channel(iface, skip_radar) < 0) {
 				hostapd_set_state(iface, HAPD_IFACE_DFS);
 				return 0;
 			}
-
-			iface->freq = channel->freq;
-			iface->conf->channel = channel->chan;
-			iface->conf->secondary_channel = sec;
-			hostapd_set_oper_centr_freq_seg0_idx(iface->conf, cf1);
-			hostapd_set_oper_centr_freq_seg1_idx(iface->conf, cf2);
 		}
 	} while (res);
 
 	/* Finally start CAC */
 	hostapd_set_state(iface, HAPD_IFACE_DFS);
-	wpa_printf(MSG_DEBUG, "DFS start CAC on %d MHz", iface->freq);
+	radar_offchan = hostapd_is_radar_offchan_enabled(iface);
+	wpa_printf(MSG_DEBUG, "DFS start CAC on %d MHz offchan %d",
+		   iface->freq, radar_offchan);
 	wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, DFS_EVENT_CAC_START
 		"freq=%d chan=%d sec_chan=%d, width=%d, seg0=%d, seg1=%d, cac_time=%ds",
 		iface->freq,
@@ -863,13 +908,37 @@ int hostapd_handle_dfs(struct hostapd_iface *iface)
 		iface->conf->secondary_channel,
 		hostapd_get_oper_chwidth(iface->conf),
 		hostapd_get_oper_centr_freq_seg0_idx(iface->conf),
-		hostapd_get_oper_centr_freq_seg1_idx(iface->conf));
+		hostapd_get_oper_centr_freq_seg1_idx(iface->conf),
+		radar_offchan);
 
 	if (res) {
 		wpa_printf(MSG_ERROR, "DFS start_dfs_cac() failed, %d", res);
 		return -1;
 	}
 
+	if (radar_offchan) {
+		/* Cache offchannel radar parameters */
+		iface->radar_offchan.channel = iface->conf->channel;
+		iface->radar_offchan.secondary_channel =
+			iface->conf->secondary_channel;
+		iface->radar_offchan.freq = iface->freq;
+		iface->radar_offchan.centr_freq_seg0_idx =
+			hostapd_get_oper_centr_freq_seg0_idx(iface->conf);
+		iface->radar_offchan.centr_freq_seg1_idx =
+			hostapd_get_oper_centr_freq_seg1_idx(iface->conf);
+
+		/*
+		 * Let's select a random channel for the moment
+		 * and perform CAC on dedicated radar chain
+		 */
+		res = dfs_set_valid_channel(iface, 1);
+		if (res < 0)
+			return res;
+
+		iface->radar_offchan.temp_ch = 1;
+		return 1;
+	}
+
 	return 0;
 }
 
@@ -890,6 +959,157 @@ int hostapd_is_dfs_chan_available(struct hostapd_iface *iface)
 	return dfs_check_chans_available(iface, start_chan_idx, n_chans);
 }
 
+static int hostapd_dfs_request_channel_switch(struct hostapd_iface *iface,
+					      int channel, int freq,
+					      int secondary_channel,
+					      u8 oper_centr_freq_seg0_idx,
+					      u8 oper_centr_freq_seg1_idx)
+{
+	struct hostapd_hw_modes *cmode = iface->current_mode;
+	int ieee80211_mode = IEEE80211_MODE_AP, err, i;
+	struct csa_settings csa_settings;
+	u8 new_vht_oper_chwidth;
+
+	wpa_printf(MSG_DEBUG, "DFS will switch to a new channel %d", channel);
+	wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, DFS_EVENT_NEW_CHANNEL
+		"freq=%d chan=%d sec_chan=%d", freq, channel,
+		secondary_channel);
+
+	new_vht_oper_chwidth = hostapd_get_oper_chwidth(iface->conf);
+	hostapd_set_oper_chwidth(iface->conf,
+				 hostapd_get_oper_chwidth(iface->conf));
+
+	/* Setup CSA request */
+	os_memset(&csa_settings, 0, sizeof(csa_settings));
+	csa_settings.cs_count = 5;
+	csa_settings.block_tx = 1;
+#ifdef CONFIG_MESH
+	if (iface->mconf)
+		ieee80211_mode = IEEE80211_MODE_MESH;
+#endif /* CONFIG_MESH */
+	err = hostapd_set_freq_params(&csa_settings.freq_params,
+				      iface->conf->hw_mode,
+				      freq, channel,
+				      iface->conf->enable_edmg,
+				      iface->conf->edmg_channel,
+				      iface->conf->ieee80211n,
+				      iface->conf->ieee80211ac,
+				      iface->conf->ieee80211ax,
+				      secondary_channel,
+				      new_vht_oper_chwidth,
+				      oper_centr_freq_seg0_idx,
+				      oper_centr_freq_seg1_idx,
+				      cmode->vht_capab,
+				      &cmode->he_capab[ieee80211_mode]);
+
+	if (err) {
+		wpa_printf(MSG_ERROR, "DFS failed to calculate CSA freq params");
+		hostapd_disable_iface(iface);
+		return err;
+	}
+
+	for (i = 0; i < iface->num_bss; i++) {
+		err = hostapd_switch_channel(iface->bss[i], &csa_settings);
+		if (err)
+			break;
+	}
+
+	if (err) {
+		wpa_printf(MSG_WARNING, "DFS failed to schedule CSA (%d) - trying fallback",
+			   err);
+		iface->freq = freq;
+		iface->conf->channel = channel;
+		iface->conf->secondary_channel = secondary_channel;
+		hostapd_set_oper_chwidth(iface->conf, new_vht_oper_chwidth);
+		hostapd_set_oper_centr_freq_seg0_idx(iface->conf,
+						     oper_centr_freq_seg0_idx);
+		hostapd_set_oper_centr_freq_seg1_idx(iface->conf,
+						     oper_centr_freq_seg1_idx);
+
+		hostapd_disable_iface(iface);
+		hostapd_enable_iface(iface);
+
+		return 0;
+	}
+
+	/* Channel configuration will be updated once CSA completes and
+	 * ch_switch_notify event is received */
+	wpa_printf(MSG_DEBUG, "DFS waiting channel switch event");
+
+	return 0;
+}
+
+static struct hostapd_channel_data *
+dfs_downgrade_bandwidth(struct hostapd_iface *iface, int *secondary_channel,
+			u8 *oper_centr_freq_seg0_idx,
+			u8 *oper_centr_freq_seg1_idx, int *skip_radar);
+
+static void
+hostpad_dfs_update_offchannel_chain(struct hostapd_iface *iface)
+{
+	struct hostapd_channel_data *channel;
+	int sec = 0, flags = 2;
+	u8 cf1 = 0, cf2 = 0;
+
+	channel = dfs_get_valid_channel(iface, &sec, &cf1, &cf2, 2);
+	if (!channel || channel->chan == iface->conf->channel)
+		channel = dfs_downgrade_bandwidth(iface, &sec, &cf1, &cf2,
+						  &flags);
+	if (!channel ||
+	    hostapd_start_dfs_cac(iface, iface->conf->hw_mode,
+				  channel->freq, channel->chan,
+				  iface->conf->ieee80211n,
+				  iface->conf->ieee80211ac,
+				  iface->conf->ieee80211ax,
+				  sec, hostapd_get_oper_chwidth(iface->conf),
+				  cf1, cf2, 1)) {
+		/*
+		 * Toggle interface state to enter DFS state
+		 * until NOP is finished.
+		 */
+		wpa_printf(MSG_ERROR, "DFS failed start CAC offchannel");
+		return;
+	}
+
+	wpa_printf(MSG_DEBUG, "%s: setting offchannel chain to chan %d (%d MHz)",
+		   __func__, channel->chan, channel->freq);
+
+	iface->radar_offchan.channel = channel->chan;
+	iface->radar_offchan.freq = channel->freq;
+	iface->radar_offchan.secondary_channel = sec;
+	iface->radar_offchan.centr_freq_seg0_idx = cf1;
+	iface->radar_offchan.centr_freq_seg1_idx = cf2;
+}
+
+/* FIXME: check if all channel bandwith */
+static int
+hostapd_dfs_is_offchan_event(struct hostapd_iface *iface, int freq)
+{
+	if (iface->radar_offchan.freq != freq)
+		return 0;
+
+	return 1;
+}
+
+static int
+hostapd_dfs_start_channel_switch_offchan(struct hostapd_iface *iface)
+{
+	iface->conf->channel = iface->radar_offchan.channel;
+	iface->freq = iface->radar_offchan.freq;
+	iface->conf->secondary_channel =
+		iface->radar_offchan.secondary_channel;
+	hostapd_set_oper_centr_freq_seg0_idx(iface->conf,
+			iface->radar_offchan.centr_freq_seg0_idx);
+	hostapd_set_oper_centr_freq_seg1_idx(iface->conf,
+			iface->radar_offchan.centr_freq_seg1_idx);
+
+	hostpad_dfs_update_offchannel_chain(iface);
+
+	return hostapd_dfs_request_channel_switch(iface, iface->conf->channel,
+						  iface->freq, iface->conf->secondary_channel,
+						  hostapd_get_oper_centr_freq_seg0_idx(iface->conf),
+						  hostapd_get_oper_centr_freq_seg1_idx(iface->conf));
+}
 
 int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 			     int ht_enabled, int chan_offset, int chan_width,
@@ -911,6 +1131,23 @@ int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 			set_dfs_state(iface, freq, ht_enabled, chan_offset,
 				      chan_width, cf1, cf2,
 				      HOSTAPD_CHAN_DFS_AVAILABLE);
+
+			/*
+			 * radar event from offchannel chain for selected
+			 * channel. Perfrom CSA, move main chain to selected
+			 * channel and configure offchannel chain to a new DFS
+			 * channel
+			 */
+			if (hostapd_is_radar_offchan_enabled(iface) &&
+			    hostapd_dfs_is_offchan_event(iface, freq)) {
+				iface->radar_offchan.cac_started = 0;
+				if (iface->radar_offchan.temp_ch) {
+					iface->radar_offchan.temp_ch = 0;
+					return hostapd_dfs_start_channel_switch_offchan(iface);
+				}
+				return 0;
+			}
+
 			/*
 			 * Just mark the channel available when CAC completion
 			 * event is received in enabled state. CAC result could
@@ -927,6 +1164,10 @@ int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 				iface->cac_started = 0;
 			}
 		}
+	} else if (hostapd_is_radar_offchan_enabled(iface) &&
+		   hostapd_dfs_is_offchan_event(iface, freq)) {
+		iface->radar_offchan.cac_started = 0;
+		hostpad_dfs_update_offchannel_chain(iface);
 	}
 
 	return 0;
@@ -1036,6 +1277,44 @@ static int hostapd_dfs_start_channel_switch_cac(struct hostapd_iface *iface)
 	return err;
 }
 
+static int
+hostapd_dfs_offchan_start_channel_switch(struct hostapd_iface *iface, int freq)
+{
+	if (!hostapd_is_radar_offchan_enabled(iface))
+		return -1; /* Offchannel chain not supported */
+
+	wpa_printf(MSG_DEBUG,
+		   "%s called (offchannel CAC active: %s, CSA active: %s)",
+		   __func__, iface->radar_offchan.cac_started ? "yes" : "no",
+		   hostapd_csa_in_progress(iface) ? "yes" : "no");
+
+	/* Check if CSA in progress */
+	if (hostapd_csa_in_progress(iface))
+		return 0;
+
+	/*
+	 * If offchannel radar detation is supported and radar channel
+	 * monitored by offchain is available switch to it without waiting
+	 * for the CAC otherwise let's keep a random channel.
+	 * If radar pattern is reported on offchannel chain, just switch to
+	 * monitor another radar channel.
+	 */
+	if (hostapd_dfs_is_offchan_event(iface, freq)) {
+		hostpad_dfs_update_offchannel_chain(iface);
+		return 0;
+	}
+
+	/* Offchannel not availanle yet. Perform CAC on main chain */
+	if (iface->radar_offchan.cac_started) {
+		/* We want to switch to monitored channel as soon as
+		 * CAC is completed.
+		 */
+		iface->radar_offchan.temp_ch = 1;
+		return -1;
+	}
+
+	return hostapd_dfs_start_channel_switch_offchan(iface);
+}
 
 static int hostapd_dfs_start_channel_switch(struct hostapd_iface *iface)
 {
@@ -1043,13 +1322,7 @@ static int hostapd_dfs_start_channel_switch(struct hostapd_iface *iface)
 	int secondary_channel;
 	u8 oper_centr_freq_seg0_idx;
 	u8 oper_centr_freq_seg1_idx;
-	u8 new_vht_oper_chwidth;
 	int skip_radar = 1;
-	struct csa_settings csa_settings;
-	unsigned int i;
-	int err = 1;
-	struct hostapd_hw_modes *cmode = iface->current_mode;
-	u8 current_vht_oper_chwidth = hostapd_get_oper_chwidth(iface->conf);
 	int ieee80211_mode = IEEE80211_MODE_AP;
 
 	wpa_printf(MSG_DEBUG, "%s called (CAC active: %s, CSA active: %s)",
@@ -1113,73 +1386,16 @@ static int hostapd_dfs_start_channel_switch(struct hostapd_iface *iface)
 		}
 	}
 
-	wpa_printf(MSG_DEBUG, "DFS will switch to a new channel %d",
-		   channel->chan);
-	wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, DFS_EVENT_NEW_CHANNEL
-		"freq=%d chan=%d sec_chan=%d", channel->freq,
-		channel->chan, secondary_channel);
-
-	new_vht_oper_chwidth = hostapd_get_oper_chwidth(iface->conf);
-	hostapd_set_oper_chwidth(iface->conf, current_vht_oper_chwidth);
-
-	/* Setup CSA request */
-	os_memset(&csa_settings, 0, sizeof(csa_settings));
-	csa_settings.cs_count = 5;
-	csa_settings.block_tx = 1;
 #ifdef CONFIG_MESH
 	if (iface->mconf)
 		ieee80211_mode = IEEE80211_MODE_MESH;
 #endif /* CONFIG_MESH */
-	err = hostapd_set_freq_params(&csa_settings.freq_params,
-				      iface->conf->hw_mode,
-				      channel->freq,
-				      channel->chan,
-				      iface->conf->enable_edmg,
-				      iface->conf->edmg_channel,
-				      iface->conf->ieee80211n,
-				      iface->conf->ieee80211ac,
-				      iface->conf->ieee80211ax,
-				      secondary_channel,
-				      new_vht_oper_chwidth,
-				      oper_centr_freq_seg0_idx,
-				      oper_centr_freq_seg1_idx,
-				      cmode->vht_capab,
-				      &cmode->he_capab[ieee80211_mode]);
-
-	if (err) {
-		wpa_printf(MSG_ERROR, "DFS failed to calculate CSA freq params");
-		hostapd_disable_iface(iface);
-		return err;
-	}
 
-	for (i = 0; i < iface->num_bss; i++) {
-		err = hostapd_switch_channel(iface->bss[i], &csa_settings);
-		if (err)
-			break;
-	}
-
-	if (err) {
-		wpa_printf(MSG_WARNING, "DFS failed to schedule CSA (%d) - trying fallback",
-			   err);
-		iface->freq = channel->freq;
-		iface->conf->channel = channel->chan;
-		iface->conf->secondary_channel = secondary_channel;
-		hostapd_set_oper_chwidth(iface->conf, new_vht_oper_chwidth);
-		hostapd_set_oper_centr_freq_seg0_idx(iface->conf,
-						     oper_centr_freq_seg0_idx);
-		hostapd_set_oper_centr_freq_seg1_idx(iface->conf,
-						     oper_centr_freq_seg1_idx);
-
-		hostapd_disable_iface(iface);
-		hostapd_enable_iface(iface);
-		return 0;
-	}
-
-	/* Channel configuration will be updated once CSA completes and
-	 * ch_switch_notify event is received */
-
-	wpa_printf(MSG_DEBUG, "DFS waiting channel switch event");
-	return 0;
+	return hostapd_dfs_request_channel_switch(iface, channel->chan,
+						  channel->freq,
+						  secondary_channel,
+						  oper_centr_freq_seg0_idx,
+						  oper_centr_freq_seg1_idx);
 }
 
 
@@ -1208,15 +1424,19 @@ int hostapd_dfs_radar_detected(struct hostapd_iface *iface, int freq,
 	if (!res)
 		return 0;
 
-	/* Skip if reported radar event not overlapped our channels */
-	res = dfs_are_channels_overlapped(iface, freq, chan_width, cf1, cf2);
-	if (!res)
-		return 0;
+	if (!hostapd_dfs_is_offchan_event(iface, freq)) {
+		/* Skip if reported radar event not overlapped our channels */
+		res = dfs_are_channels_overlapped(iface, freq, chan_width,
+						  cf1, cf2);
+		if (!res)
+			return 0;
+	}
 
-	/* radar detected while operating, switch the channel. */
-	res = hostapd_dfs_start_channel_switch(iface);
+	if (hostapd_dfs_offchan_start_channel_switch(iface, freq))
+		/* radar detected while operating, switch the channel. */
+		return hostapd_dfs_start_channel_switch(iface);
 
-	return res;
+	return 0;
 }
 
 
@@ -1284,7 +1504,11 @@ int hostapd_dfs_start_cac(struct hostapd_iface *iface, int freq,
 		"seg1=%d cac_time=%ds",
 		freq, (freq - 5000) / 5, chan_offset, chan_width, cf1, cf2,
 		iface->dfs_cac_ms / 1000);
-	iface->cac_started = 1;
+
+	if (hostapd_dfs_is_offchan_event(iface, freq))
+		iface->radar_offchan.cac_started = 1;
+	else
+		iface->cac_started = 1;
 	os_get_reltime(&iface->dfs_cac_start);
 	return 0;
 }
diff --git a/src/ap/hostapd.h b/src/ap/hostapd.h
index 27b985d..1c6c94e 100644
--- a/src/ap/hostapd.h
+++ b/src/ap/hostapd.h
@@ -521,6 +521,21 @@ struct hostapd_iface {
 	int *basic_rates;
 	int freq;
 
+	/* Offchanel chain configuration */
+	struct {
+		int channel;
+		int secondary_channel;
+		int freq;
+		int centr_freq_seg0_idx;
+		int centr_freq_seg1_idx;
+		/* Main chain is on temporary channel during
+		 * CAC detection on radar offchain
+		 */
+		unsigned int temp_ch:1;
+		/* CAC started on radar offchain */
+		unsigned int cac_started:1;
+	} radar_offchan;
+
 	u16 hw_flags;
 
 	/* Number of associated Non-ERP stations (i.e., stations using 802.11b
diff --git a/src/drivers/driver.h b/src/drivers/driver.h
index 6d9194f..7ed47c0 100644
--- a/src/drivers/driver.h
+++ b/src/drivers/driver.h
@@ -777,6 +777,11 @@ struct hostapd_freq_params {
 	 * for IEEE 802.11ay EDMG configuration.
 	 */
 	struct ieee80211_edmg_config edmg;
+
+	/**
+	 * radar_offchan - Whether radar/CAC offchannel is requested
+	 */
+	int radar_offchan;
 };
 
 /**
@@ -2026,6 +2031,8 @@ struct wpa_driver_capa {
 #define WPA_DRIVER_FLAGS2_OCV			0x0000000000000080ULL
 /** Driver expects user space implementation of SME in AP mode */
 #define WPA_DRIVER_FLAGS2_AP_SME		0x0000000000000100ULL
+/** Driver supports offchannel radar/CAC detection */
+#define WPA_DRIVER_RADAR_OFFCHAN		0x0000000000000200ULL
 	u64 flags2;
 
 #define FULL_AP_CLIENT_STATE_SUPP(drv_flags) \
diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 4db8cce..62c3cd8 100644
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -4885,6 +4885,7 @@ static int nl80211_put_freq_params(struct nl_msg *msg,
 	wpa_printf(MSG_DEBUG, "  * he_enabled=%d", freq->he_enabled);
 	wpa_printf(MSG_DEBUG, "  * vht_enabled=%d", freq->vht_enabled);
 	wpa_printf(MSG_DEBUG, "  * ht_enabled=%d", freq->ht_enabled);
+	wpa_printf(MSG_DEBUG, "  * radar_offchan=%d", freq->radar_offchan);
 
 	hw_mode = ieee80211_freq_to_chan(freq->freq, &channel);
 	is_24ghz = hw_mode == HOSTAPD_MODE_IEEE80211G ||
@@ -4962,6 +4963,9 @@ static int nl80211_put_freq_params(struct nl_msg *msg,
 				NL80211_CHAN_NO_HT))
 			return -ENOBUFS;
 	}
+	if (freq->radar_offchan)
+		nla_put_flag(msg, NL80211_ATTR_RADAR_OFFCHAN);
+
 	return 0;
 }
 
diff --git a/src/drivers/driver_nl80211_capa.c b/src/drivers/driver_nl80211_capa.c
index cd596e3..e370ef3 100644
--- a/src/drivers/driver_nl80211_capa.c
+++ b/src/drivers/driver_nl80211_capa.c
@@ -665,6 +665,10 @@ static void wiphy_info_ext_feature_flags(struct wiphy_info_data *info,
 	if (ext_feature_isset(ext_features, len,
 			      NL80211_EXT_FEATURE_OPERATING_CHANNEL_VALIDATION))
 		capa->flags2 |= WPA_DRIVER_FLAGS2_OCV;
+
+	if (ext_feature_isset(ext_features, len,
+			      NL80211_EXT_FEATURE_RADAR_OFFCHAN))
+		capa->flags2 |= WPA_DRIVER_RADAR_OFFCHAN;
 }
 
 
diff --git a/src/drivers/nl80211_copy.h b/src/drivers/nl80211_copy.h
index f7be755..736b483 100644
--- a/src/drivers/nl80211_copy.h
+++ b/src/drivers/nl80211_copy.h
@@ -2573,6 +2573,10 @@ enum nl80211_commands {
  * @NL80211_ATTR_WIPHY_ANTENNA_GAIN: Configured antenna gain. Used to reduce
  *	transmit power to stay within regulatory limits. u32, dBi.
  *
+ * @NL80211_ATTR_RADAR_OFFCHAN: Configure dedicated chain available for radar
+ *	detection on some hw. The chain can't be used to transmits or receives
+ *	frames. The driver is supposed to implement CAC management in sw or fw.
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -3078,6 +3082,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_WIPHY_ANTENNA_GAIN,
 
+	NL80211_ATTR_RADAR_OFFCHAN,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -5974,6 +5980,9 @@ enum nl80211_feature_flags {
  * @NL80211_EXT_FEATURE_BSS_COLOR: The driver supports BSS color collision
  *	detection and change announcemnts.
  *
+ * @NL80211_EXT_FEATURE_RADAR_OFFCHAN: Device supports offchannel radar/CAC
+ *	detection.
+ *
  * @NUM_NL80211_EXT_FEATURES: number of extended features.
  * @MAX_NL80211_EXT_FEATURES: highest extended feature index.
  */
@@ -6039,6 +6048,7 @@ enum nl80211_ext_feature_index {
 	NL80211_EXT_FEATURE_SECURE_RTT,
 	NL80211_EXT_FEATURE_PROT_RANGE_NEGO_AND_MEASURE,
 	NL80211_EXT_FEATURE_BSS_COLOR,
+	NL80211_EXT_FEATURE_RADAR_OFFCHAN,
 
 	/* add new features before the definition below */
 	NUM_NL80211_EXT_FEATURES,