mac80211: support RX_FLAG_MACTIME_END

Allow drivers to indicate their mactime is at RX completion and adjust
for this in mac80211. Also rename the existing RX_FLAG_MACTIME_MPDU to
RX_FLAG_MACTIME_START to clarify its intent. Based on similar code by
Johannes Berg.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
[fix docs, atheros drivers]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 5 insertions, 24 deletions

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index c7386b2..cc11558 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -543,30 +543,11 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 	if (ether_addr_equal(cbss->bssid, sdata->u.ibss.bssid))
 		goto put_bss;
 
-	if (rx_status->flag & RX_FLAG_MACTIME_MPDU) {
-		/*
-		 * For correct IBSS merging we need mactime; since mactime is
-		 * defined as the time the first data symbol of the frame hits
-		 * the PHY, and the timestamp of the beacon is defined as "the
-		 * time that the data symbol containing the first bit of the
-		 * timestamp is transmitted to the PHY plus the transmitting
-		 * STA's delays through its local PHY from the MAC-PHY
-		 * interface to its interface with the WM" (802.11 11.1.2)
-		 * - equals the time this bit arrives at the receiver - we have
-		 * to take into account the offset between the two.
-		 *
-		 * E.g. at 1 MBit that means mactime is 192 usec earlier
-		 * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
-		 */
-		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);
+	if (ieee80211_have_rx_timestamp(rx_status)) {
+		/* time when timestamp field was received */
+		rx_timestamp =
+			ieee80211_calculate_rx_timestamp(local, rx_status,
+							 len + FCS_LEN, 24);
 	} else {
 		/*
 		 * second best option: get current TSF