mac80211: (selectively) add HT details in radiotap

Add a flag for the HT format (mixed vs. greenfield)
to allow drivers to report that on receive. Not all
drivers will do that though, so allow drivers to set
which radiotap MCS details they report.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -667,6 +667,9 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
  * @RX_FLAG_SHORT_GI: Short guard interval was used
  * @RX_FLAG_NO_SIGNAL_VAL: The signal strength value is not present.
  *	Valid only for data frames (mainly A-MPDU)
+ * @RX_FLAG_HT_GF: This frame was received in a HT-greenfield transmission, if
+ *	the driver fills this value it should add %IEEE80211_RADIOTAP_MCS_HAVE_FMT
+ *	to hw.radiotap_mcs_details to advertise that fact
  */
 enum mac80211_rx_flags {
 	RX_FLAG_MMIC_ERROR	= 1<<0,
@@ -681,6 +684,7 @@ enum mac80211_rx_flags {
 	RX_FLAG_40MHZ		= 1<<10,
 	RX_FLAG_SHORT_GI	= 1<<11,
 	RX_FLAG_NO_SIGNAL_VAL	= 1<<12,
+	RX_FLAG_HT_GF		= 1<<13,
 };
 
 /**
@@ -1288,6 +1292,11 @@ enum ieee80211_hw_flags {
  *
  * @offchannel_tx_hw_queue: HW queue ID to use for offchannel TX
  *	(if %IEEE80211_HW_QUEUE_CONTROL is set)
+ *
+ * @radiotap_mcs_details: lists which MCS information can the HW
+ *	reports, by default it is set to _MCS, _GI and _BW but doesn't
+ *	include _FMT. Use %IEEE80211_RADIOTAP_MCS_HAVE_* values, only
+ *	adding _BW is supported today.
  */
 struct ieee80211_hw {
 	struct ieee80211_conf conf;
@@ -1309,6 +1318,7 @@ struct ieee80211_hw {
 	u8 max_rx_aggregation_subframes;
 	u8 max_tx_aggregation_subframes;
 	u8 offchannel_tx_hw_queue;
+	u8 radiotap_mcs_details;
 };
 
 /**

net/mac80211/main.c

@@ -596,6 +596,9 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
 	local->hw.offchannel_tx_hw_queue = IEEE80211_INVAL_HW_QUEUE;
 	local->hw.conf.long_frame_max_tx_count = wiphy->retry_long;
 	local->hw.conf.short_frame_max_tx_count = wiphy->retry_short;
+	local->hw.radiotap_mcs_details = IEEE80211_RADIOTAP_MCS_HAVE_MCS |
+					 IEEE80211_RADIOTAP_MCS_HAVE_GI |
+					 IEEE80211_RADIOTAP_MCS_HAVE_BW;
 	local->user_power_level = -1;
 	wiphy->ht_capa_mod_mask = &mac80211_ht_capa_mod_mask;
 

net/mac80211/rx.c

@@ -204,14 +204,14 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 
 	if (status->flag & RX_FLAG_HT) {
 		rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_MCS);
-		*pos++ = IEEE80211_RADIOTAP_MCS_HAVE_MCS |
-			 IEEE80211_RADIOTAP_MCS_HAVE_GI |
-			 IEEE80211_RADIOTAP_MCS_HAVE_BW;
+		*pos++ = local->hw.radiotap_mcs_details;
 		*pos = 0;
 		if (status->flag & RX_FLAG_SHORT_GI)
 			*pos |= IEEE80211_RADIOTAP_MCS_SGI;
 		if (status->flag & RX_FLAG_40MHZ)
 			*pos |= IEEE80211_RADIOTAP_MCS_BW_40;
+		if (status->flag & RX_FLAG_HT_GF)
+			*pos |= IEEE80211_RADIOTAP_MCS_FMT_GF;
 		pos++;
 		*pos++ = status->rate_idx;
 	}