ath9k: Support RSN IBSS

Add support for using RSN IBSS with ath9k. For now, this uses software
crypto for group addressed frames in RSN IBSS, but that may be
optimized in the future by extending the key cache design to support
per-STA RX GTK.
Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/init.c

@@ -690,6 +690,8 @@ void ath9k_set_hw_capab(struct ath_softc *sc, struct ieee80211_hw *hw)
 	if (AR_SREV_5416(sc->sc_ah))
 		hw->wiphy->flags &= ~WIPHY_FLAG_PS_ON_BY_DEFAULT;
 
+	hw->wiphy->flags |= WIPHY_FLAG_IBSS_RSN;
+
 	hw->queues = 4;
 	hw->max_rates = 4;
 	hw->channel_change_time = 5000;

drivers/net/wireless/ath/ath9k/main.c

@@ -1845,6 +1845,20 @@ static int ath9k_set_key(struct ieee80211_hw *hw,
 	if (ath9k_modparam_nohwcrypt)
 		return -ENOSPC;
 
+	if (vif->type == NL80211_IFTYPE_ADHOC &&
+	    (key->cipher == WLAN_CIPHER_SUITE_TKIP ||
+	     key->cipher == WLAN_CIPHER_SUITE_CCMP) &&
+	    !(key->flags & IEEE80211_KEY_FLAG_PAIRWISE)) {
+		/*
+		 * For now, disable hw crypto for the RSN IBSS group keys. This
+		 * could be optimized in the future to use a modified key cache
+		 * design to support per-STA RX GTK, but until that gets
+		 * implemented, use of software crypto for group addressed
+		 * frames is a acceptable to allow RSN IBSS to be used.
+		 */
+		return -EOPNOTSUPP;
+	}
+
 	mutex_lock(&sc->mutex);
 	ath9k_ps_wakeup(sc);
 	ath_dbg(common, ATH_DBG_CONFIG, "Set HW Key\n");