mac80211: add beacon_loss debugfs file

Add beacon_loss debugfs file that emulates
ieee80211_beacon_loss call from the driver.

This can be used for various testing scenarios.
Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/debugfs_netdev.c

@@ -358,6 +358,18 @@ static ssize_t ieee80211_if_parse_tkip_mic_test(
 }
 IEEE80211_IF_FILE_W(tkip_mic_test);
 
+static ssize_t ieee80211_if_parse_beacon_loss(
+	struct ieee80211_sub_if_data *sdata, const char *buf, int buflen)
+{
+	if (!ieee80211_sdata_running(sdata) || !sdata->vif.bss_conf.assoc)
+		return -ENOTCONN;
+
+	ieee80211_beacon_loss(&sdata->vif);
+
+	return buflen;
+}
+IEEE80211_IF_FILE_W(beacon_loss);
+
 static ssize_t ieee80211_if_fmt_uapsd_queues(
 	const struct ieee80211_sub_if_data *sdata, char *buf, int buflen)
 {
@@ -569,6 +581,7 @@ static void add_sta_files(struct ieee80211_sub_if_data *sdata)
 	DEBUGFS_ADD(beacon_timeout);
 	DEBUGFS_ADD_MODE(smps, 0600);
 	DEBUGFS_ADD_MODE(tkip_mic_test, 0200);
+	DEBUGFS_ADD_MODE(beacon_loss, 0200);
 	DEBUGFS_ADD_MODE(uapsd_queues, 0600);
 	DEBUGFS_ADD_MODE(uapsd_max_sp_len, 0600);
 }