mac80211: add support for parsing ADDBA_EXT IEs

ADDBA_EXT IEs can be used to negotiate the BA fragmentation level.
Signed-off-by: John Crispin <john@phrozen.org>
Link: https://lore.kernel.org/r/20190713163642.18491-2-john@phrozen.orgSigned-off-by: Johannes Berg <johannes.berg@intel.com>

include/linux/ieee80211.h

@@ -881,6 +881,14 @@ struct ieee80211_tpc_report_ie {
 	u8 link_margin;
 } __packed;
 
+#define IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK	GENMASK(2, 1)
+#define IEEE80211_ADDBA_EXT_FRAG_LEVEL_SHIFT	1
+#define IEEE80211_ADDBA_EXT_NO_FRAG		BIT(0)
+
+struct ieee80211_addba_ext_ie {
+	u8 data;
+} __packed;
+
 struct ieee80211_mgmt {
 	__le16 frame_control;
 	__le16 duration;

net/mac80211/ieee80211_i.h

@@ -1506,6 +1506,7 @@ struct ieee802_11_elems {
 	u8 max_bssid_indicator;
 	u8 dtim_count;
 	u8 dtim_period;
+	const struct ieee80211_addba_ext_ie *addba_ext_ie;
 
 	/* length of them, respectively */
 	u8 ext_capab_len;

net/mac80211/util.c

@@ -1200,6 +1200,13 @@ _ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 
 			elems->cisco_dtpc_elem = pos;
 			break;
+		case WLAN_EID_ADDBA_EXT:
+			if (elen != sizeof(struct ieee80211_addba_ext_ie)) {
+				elem_parse_failed = true;
+				break;
+			}
+			elems->addba_ext_ie = (void *)pos;
+			break;
 		case WLAN_EID_TIMEOUT_INTERVAL:
 			if (elen >= sizeof(struct ieee80211_timeout_interval_ie))
 				elems->timeout_int = (void *)pos;