cfg80211: allow restricting supported dfs regions

At the moment, the ath9k/ath10k DFS module only supports detecting ETSI
radar patterns.
Add a bitmap in the interface combinations, indicating which DFS regions
are supported by the detector. If unset, support for all regions is
assumed.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/util.c b/net/wireless/util.c
index a756429..8c61d5c 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1274,10 +1274,20 @@
 					    void *data),
 			       void *data)
 {
+	const struct ieee80211_regdomain *regdom;
+	enum nl80211_dfs_regions region = 0;
 	int i, j, iftype;
 	int num_interfaces = 0;
 	u32 used_iftypes = 0;
 
+	if (radar_detect) {
+		rcu_read_lock();
+		regdom = rcu_dereference(cfg80211_regdomain);
+		if (regdom)
+			region = regdom->dfs_region;
+		rcu_read_unlock();
+	}
+
 	for (iftype = 0; iftype < NUM_NL80211_IFTYPES; iftype++) {
 		num_interfaces += iftype_num[iftype];
 		if (iftype_num[iftype] > 0 &&
@@ -1318,6 +1328,10 @@
 		if (radar_detect != (c->radar_detect_widths & radar_detect))
 			goto cont;
 
+		if (radar_detect && c->radar_detect_regions &&
+		    !(c->radar_detect_regions & BIT(region)))
+			goto cont;
+
 		/* Finally check that all iftypes that we're currently
 		 * using are actually part of this combination. If they
 		 * aren't then we can't use this combination and have