+static bool is_ht40_not_allowed(struct ieee80211_channel *chan)
+{
+ if (!chan)
+ return true;
+ if (chan->flags & IEEE80211_CHAN_DISABLED)
+ return true;
+ /* This would happen when regulatory rules disallow HT40 completely */
+ if (IEEE80211_CHAN_NO_HT40 == (chan->flags & (IEEE80211_CHAN_NO_HT40)))
+ return true;
+ return false;
+}
+
+static void reg_process_ht_flags_channel(struct wiphy *wiphy,
+ enum ieee80211_band band,
+ unsigned int chan_idx)
+{
+ struct ieee80211_supported_band *sband;
+ struct ieee80211_channel *channel;
+ struct ieee80211_channel *channel_before = NULL, *channel_after = NULL;
+ unsigned int i;
+
+ assert_cfg80211_lock();
+
+ sband = wiphy->bands[band];
+ BUG_ON(chan_idx >= sband->n_channels);
+ channel = &sband->channels[chan_idx];
+
+ if (is_ht40_not_allowed(channel)) {
+ channel->flags |= IEEE80211_CHAN_NO_HT40;
+ return;
+ }
+
+ /*
+ * We need to ensure the extension channels exist to
+ * be able to use HT40- or HT40+, this finds them (or not)
+ */
+ for (i = 0; i < sband->n_channels; i++) {
+ struct ieee80211_channel *c = &sband->channels[i];
+ if (c->center_freq == (channel->center_freq - 20))
+ channel_before = c;
+ if (c->center_freq == (channel->center_freq + 20))
+ channel_after = c;
+ }
+
+ /*
+ * Please note that this assumes target bandwidth is 20 MHz,
+ * if that ever changes we also need to change the below logic
+ * to include that as well.
+ */
+ if (is_ht40_not_allowed(channel_before))
+ channel->flags |= IEEE80211_CHAN_NO_FAT_BELOW;
+ else
+ channel->flags &= ~IEEE80211_CHAN_NO_FAT_BELOW;
+
+ if (is_ht40_not_allowed(channel_after))
+ channel->flags |= IEEE80211_CHAN_NO_FAT_ABOVE;
+ else
+ channel->flags &= ~IEEE80211_CHAN_NO_FAT_ABOVE;
+}
+
+static void reg_process_ht_flags_band(struct wiphy *wiphy,
+ enum ieee80211_band band)
+{
+ unsigned int i;
+ struct ieee80211_supported_band *sband;
+
+ BUG_ON(!wiphy->bands[band]);
+ sband = wiphy->bands[band];
+
+ for (i = 0; i < sband->n_channels; i++)
+ reg_process_ht_flags_channel(wiphy, band, i);
+}
+
+static void reg_process_ht_flags(struct wiphy *wiphy)
+{
+ enum ieee80211_band band;
+
+ if (!wiphy)
+ return;
+
+ for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
+ if (wiphy->bands[band])
+ reg_process_ht_flags_band(wiphy, band);
+ }
+
+}
+