mac80211: Add HT rates into RX status reporting

This patch adds option for HT-enabled drivers to report HT rates
(HT20/HT40, short GI, MCS index) to mac80211. These rates are
currently not in the rate table, so the rate_idx is used to indicate
MCS index.
Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -436,6 +436,9 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
  *	is valid. This is useful in monitor mode and necessary for beacon frames
  *	to enable IBSS merging.
  * @RX_FLAG_SHORTPRE: Short preamble was used for this frame
+ * @RX_FLAG_HT: HT MCS was used and rate_idx is MCS index
+ * @RX_FLAG_40MHZ: HT40 (40 MHz) was used
+ * @RX_FLAG_SHORT_GI: Short guard interval was used
  */
 enum mac80211_rx_flags {
 	RX_FLAG_MMIC_ERROR	= 1<<0,
@@ -446,7 +449,10 @@ enum mac80211_rx_flags {
 	RX_FLAG_FAILED_FCS_CRC	= 1<<5,
 	RX_FLAG_FAILED_PLCP_CRC = 1<<6,
 	RX_FLAG_TSFT		= 1<<7,
-	RX_FLAG_SHORTPRE	= 1<<8
+	RX_FLAG_SHORTPRE	= 1<<8,
+	RX_FLAG_HT		= 1<<9,
+	RX_FLAG_40MHZ		= 1<<10,
+	RX_FLAG_SHORT_GI	= 1<<11,
 };
 
 /**
@@ -466,7 +472,8 @@ enum mac80211_rx_flags {
  * @noise: noise when receiving this frame, in dBm.
  * @qual: overall signal quality indication, in percent (0-100).
  * @antenna: antenna used
- * @rate_idx: index of data rate into band's supported rates
+ * @rate_idx: index of data rate into band's supported rates or MCS index if
+ *	HT rates are use (RX_FLAG_HT)
  * @flag: %RX_FLAG_*
  */
 struct ieee80211_rx_status {

net/mac80211/mlme.c

@@ -1613,8 +1613,13 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 			 * e.g: at 1 MBit that means mactime is 192 usec earlier
 			 * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
 			 */
-			int rate = local->hw.wiphy->bands[band]->
+			int rate;
+			if (rx_status->flag & RX_FLAG_HT) {
+				rate = 65; /* TODO: HT rates */
+			} else {
+				rate = local->hw.wiphy->bands[band]->
 					bitrates[rx_status->rate_idx].bitrate;
+			}
 			rx_timestamp = rx_status->mactime + (24 * 8 * 10 / rate);
 		} else if (local && local->ops && local->ops->get_tsf)
 			/* second best option: get current TSF */

net/mac80211/rx.c

@@ -149,6 +149,16 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 	pos++;
 
 	/* IEEE80211_RADIOTAP_RATE */
+	if (status->flag & RX_FLAG_HT) {
+		/*
+		 * TODO: add following information into radiotap header once
+		 * suitable fields are defined for it:
+		 * - MCS index (status->rate_idx)
+		 * - HT40 (status->flag & RX_FLAG_40MHZ)
+		 * - short-GI (status->flag & RX_FLAG_SHORT_GI)
+		 */
+		*pos = 0;
+	} else
 		*pos = rate->bitrate / 5;
 	pos++;
 
@@ -1849,9 +1859,15 @@ static int prepare_for_handlers(struct ieee80211_sub_if_data *sdata,
 			if (!(sdata->dev->flags & IFF_PROMISC))
 				return 0;
 			rx->flags &= ~IEEE80211_RX_RA_MATCH;
-		} else if (!rx->sta)
+		} else if (!rx->sta) {
+			int rate_idx;
+			if (rx->status->flag & RX_FLAG_HT)
+				rate_idx = 0; /* TODO: HT rates */
+			else
+				rate_idx = rx->status->rate_idx;
 			rx->sta = ieee80211_ibss_add_sta(sdata, bssid, hdr->addr2,
-				BIT(rx->status->rate_idx));
+				BIT(rate_idx));
+		}
 		break;
 	case NL80211_IFTYPE_MESH_POINT:
 		if (!multicast &&
@@ -2057,7 +2073,13 @@ static u8 ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw,
 					tid_agg_rx->reorder_buf[index]->cb,
 					sizeof(status));
 				sband = local->hw.wiphy->bands[status.band];
-				rate = &sband->bitrates[status.rate_idx];
+				if (status.flag & RX_FLAG_HT) {
+					/* TODO: HT rates */
+					rate = sband->bitrates;
+				} else {
+					rate = &sband->bitrates
+						[status.rate_idx];
+				}
 				__ieee80211_rx_handle_packet(hw,
 					tid_agg_rx->reorder_buf[index],
 					&status, rate);
@@ -2101,6 +2123,9 @@ static u8 ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw,
 		memcpy(&status, tid_agg_rx->reorder_buf[index]->cb,
 			sizeof(status));
 		sband = local->hw.wiphy->bands[status.band];
+		if (status.flag & RX_FLAG_HT)
+			rate = sband->bitrates; /* TODO: HT rates */
+		else
 			rate = &sband->bitrates[status.rate_idx];
 		__ieee80211_rx_handle_packet(hw, tid_agg_rx->reorder_buf[index],
 					     &status, rate);
@@ -2189,15 +2214,26 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
 	}
 
 	sband = local->hw.wiphy->bands[status->band];
-
-	if (!sband ||
-	    status->rate_idx < 0 ||
-	    status->rate_idx >= sband->n_bitrates) {
+	if (!sband) {
 		WARN_ON(1);
 		return;
 	}
 
+	if (status->flag & RX_FLAG_HT) {
+		/* rate_idx is MCS index */
+		if (WARN_ON(status->rate_idx < 0 ||
+			    status->rate_idx >= 76))
+			return;
+		/* HT rates are not in the table - use the highest legacy rate
+		 * for now since other parts of mac80211 may not yet be fully
+		 * MCS aware. */
+		rate = &sband->bitrates[sband->n_bitrates - 1];
+	} else {
+		if (WARN_ON(status->rate_idx < 0 ||
+			    status->rate_idx >= sband->n_bitrates))
+			return;
 		rate = &sband->bitrates[status->rate_idx];
+	}
 
 	/*
 	 * key references and virtual interfaces are protected using RCU