diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index fc01de19c798..e00045c150e7 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -190,6 +190,8 @@ enum ieee80211_channel_flags {
  *	on this channel.
  * @dfs_state_entered: timestamp (jiffies) when the dfs state was entered.
  * @dfs_cac_ms: DFS CAC time in milliseconds, this is valid for DFS channels.
+ * @cac_start_time: timestamp (CLOCK_BOOTTIME, nanoseconds) when CAC was
+ *	started on this channel. Zero when CAC is not in progress.
  * @psd: power spectral density (in dBm)
  */
 struct ieee80211_channel {
@@ -207,6 +209,7 @@ struct ieee80211_channel {
 	enum nl80211_dfs_state dfs_state;
 	unsigned long dfs_state_entered;
 	unsigned int dfs_cac_ms;
+	u64 cac_start_time;
 	s8 psd;
 };
 
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index b63f71850906..c75aa039f096 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -4480,6 +4480,10 @@ enum nl80211_wmm_rule {
  *	as a non-primary subchannel. Only applicable to S1G channels.
  * @NL80211_FREQUENCY_ATTR_NO_UHR: UHR operation is not allowed on this channel
  *	in current regulatory domain.
+ * @NL80211_FREQUENCY_ATTR_CAC_START_TIME: Channel Availability Check (CAC)
+ *	start time (CLOCK_BOOTTIME, nanoseconds). Only present when CAC is
+ *	currently in progress on this channel.
+ * @NL80211_FREQUENCY_ATTR_PAD: attribute used for padding for 64-bit alignment
  * @NL80211_FREQUENCY_ATTR_MAX: highest frequency attribute number
  *	currently defined
  * @__NL80211_FREQUENCY_ATTR_AFTER_LAST: internal use
@@ -4530,6 +4534,8 @@ enum nl80211_frequency_attr {
 	NL80211_FREQUENCY_ATTR_NO_16MHZ,
 	NL80211_FREQUENCY_ATTR_S1G_NO_PRIMARY,
 	NL80211_FREQUENCY_ATTR_NO_UHR,
+	NL80211_FREQUENCY_ATTR_CAC_START_TIME,
+	NL80211_FREQUENCY_ATTR_PAD,
 
 	/* keep last */
 	__NL80211_FREQUENCY_ATTR_AFTER_LAST,
diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index 68221b1ab45e..dfe319565280 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -642,6 +642,33 @@ void cfg80211_set_dfs_state(struct wiphy *wiphy,
 	}
 }
 
+void cfg80211_set_cac_state(struct wiphy *wiphy,
+			    const struct cfg80211_chan_def *chandef,
+			    bool cac_ongoing)
+{
+	struct ieee80211_channel *c;
+	int width;
+	u64 cac_time;
+
+	if (WARN_ON(!cfg80211_chandef_valid(chandef)))
+		return;
+
+	width = cfg80211_chandef_get_width(chandef);
+	if (width < 0)
+		return;
+
+	/* Get the same timestamp for all subchannels */
+	cac_time = cac_ongoing ? ktime_get_boottime_ns() : 0;
+
+	for_each_subchan(chandef, freq, cf) {
+		c = ieee80211_get_channel_khz(wiphy, freq);
+		if (!c)
+			continue;
+
+		c->cac_start_time = cac_time;
+	}
+}
+
 static bool
 cfg80211_dfs_permissive_check_wdev(struct cfg80211_registered_device *rdev,
 				   enum nl80211_iftype iftype,
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 6ac57b7b2615..6cace846d7a3 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -481,6 +481,10 @@ void cfg80211_set_dfs_state(struct wiphy *wiphy,
 			    const struct cfg80211_chan_def *chandef,
 			    enum nl80211_dfs_state dfs_state);
 
+void cfg80211_set_cac_state(struct wiphy *wiphy,
+			    const struct cfg80211_chan_def *chandef,
+			    bool cac_ongoing);
+
 void cfg80211_dfs_channels_update_work(struct work_struct *work);
 
 void cfg80211_sched_dfs_chan_update(struct cfg80211_registered_device *rdev);
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 212178d04efa..283ea4c7c61e 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -1162,9 +1162,11 @@ void cfg80211_cac_event(struct net_device *netdev,
 		fallthrough;
 	case NL80211_RADAR_CAC_ABORTED:
 		wdev->links[link_id].cac_started = false;
+		cfg80211_set_cac_state(wiphy, chandef, false);
 		break;
 	case NL80211_RADAR_CAC_STARTED:
 		wdev->links[link_id].cac_started = true;
+		cfg80211_set_cac_state(wiphy, chandef, true);
 		break;
 	default:
 		WARN_ON(1);
@@ -1192,15 +1194,18 @@ __cfg80211_background_cac_event(struct cfg80211_registered_device *rdev,
 	switch (event) {
 	case NL80211_RADAR_CAC_FINISHED:
 		cfg80211_set_dfs_state(wiphy, chandef, NL80211_DFS_AVAILABLE);
+		cfg80211_set_cac_state(wiphy, chandef, false);
 		memcpy(&rdev->cac_done_chandef, chandef, sizeof(*chandef));
 		queue_work(cfg80211_wq, &rdev->propagate_cac_done_wk);
 		cfg80211_sched_dfs_chan_update(rdev);
 		break;
 	case NL80211_RADAR_CAC_ABORTED:
+		cfg80211_set_cac_state(wiphy, chandef, false);
 		if (!cancel_delayed_work(&rdev->background_cac_done_wk))
 			return;
 		break;
 	case NL80211_RADAR_CAC_STARTED:
+		cfg80211_set_cac_state(wiphy, chandef, true);
 		break;
 	default:
 		return;
@@ -1307,6 +1312,8 @@ void cfg80211_stop_radar_detection(struct wireless_dev *wdev)
 
 		chandef = *wdev_chandef(wdev, link_id);
 		rdev_end_cac(rdev, wdev->netdev, link_id);
+		wdev->links[link_id].cac_started = false;
+		cfg80211_set_cac_state(wiphy, &chandef, false);
 		nl80211_radar_notify(rdev, &chandef, NL80211_RADAR_CAC_ABORTED,
 				     wdev->netdev, GFP_KERNEL);
 	}
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index b94231c8441c..7e288d3ce5ae 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1333,6 +1333,12 @@ static int nl80211_msg_put_channel(struct sk_buff *msg, struct wiphy *wiphy,
 		if ((chan->flags & IEEE80211_CHAN_NO_UHR) &&
 		    nla_put_flag(msg, NL80211_FREQUENCY_ATTR_NO_UHR))
 			goto nla_put_failure;
+		if (chan->cac_start_time &&
+		    nla_put_u64_64bit(msg,
+				      NL80211_FREQUENCY_ATTR_CAC_START_TIME,
+				      chan->cac_start_time,
+				      NL80211_FREQUENCY_ATTR_PAD))
+			goto nla_put_failure;
 	}
 
 	if (nla_put_u32(msg, NL80211_FREQUENCY_ATTR_MAX_TX_POWER,
@@ -11353,6 +11359,7 @@ static int nl80211_start_radar_detection(struct sk_buff *skb,
 	wdev->links[link_id].cac_started = true;
 	wdev->links[link_id].cac_start_time = jiffies;
 	wdev->links[link_id].cac_time_ms = cac_time_ms;
+	cfg80211_set_cac_state(wiphy, &chandef, true);
 
 	return 0;
 }