cfg80211: add channel switch notify event

The firmware may decide to switch channels while already beaconing, e.g.
in response to a cfg80211 connect request on a different vif. Add this
event to notify userspace when an AP or GO interface has successfully
migrated to a new channel, so it can update its configuration
accordingly.

Signed-off-by: Thomas Pedersen <c_tpeder@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index e14fdcc..6801d96 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -930,6 +930,33 @@
 }
 EXPORT_SYMBOL(cfg80211_pmksa_candidate_notify);
 
+void cfg80211_ch_switch_notify(struct net_device *dev, int freq,
+			       enum nl80211_channel_type type)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct wiphy *wiphy = wdev->wiphy;
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+	struct ieee80211_channel *chan;
+
+	wdev_lock(wdev);
+
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_AP &&
+		    wdev->iftype != NL80211_IFTYPE_P2P_GO))
+		goto out;
+
+	chan = rdev_freq_to_chan(rdev, freq, type);
+	if (WARN_ON(!chan))
+		goto out;
+
+	wdev->channel = chan;
+
+	nl80211_ch_switch_notify(rdev, dev, freq, type, GFP_KERNEL);
+out:
+	wdev_unlock(wdev);
+	return;
+}
+EXPORT_SYMBOL(cfg80211_ch_switch_notify);
+
 bool cfg80211_rx_spurious_frame(struct net_device *dev,
 				const u8 *addr, gfp_t gfp)
 {