Index: head/sys/dev/usb/wlan/if_rum.c
===================================================================
--- head/sys/dev/usb/wlan/if_rum.c
+++ head/sys/dev/usb/wlan/if_rum.c
@@ -206,6 +206,7 @@
 static void		rum_enable_tsf_sync(struct rum_softc *);
 static void		rum_enable_tsf(struct rum_softc *);
 static void		rum_abort_tsf_sync(struct rum_softc *);
+static void		rum_get_tsf(struct rum_softc *, uint64_t *);
 static void		rum_update_slot(struct rum_softc *);
 static void		rum_set_bssid(struct rum_softc *, const uint8_t *);
 static void		rum_set_macaddr(struct rum_softc *, const uint8_t *);
@@ -857,6 +858,7 @@
 
 				tap->wt_flags = 0;
 				tap->wt_rate = data->rate;
+				rum_get_tsf(sc, &tap->wt_tsf);
 				tap->wt_antenna = sc->tx_ant;
 
 				ieee80211_radiotap_tx(vap, m);
@@ -963,11 +965,11 @@
 		if (ieee80211_radiotap_active(ic)) {
 			struct rum_rx_radiotap_header *tap = &sc->sc_rxtap;
 
-			/* XXX read tsf */
 			tap->wr_flags = 0;
 			tap->wr_rate = ieee80211_plcp2rate(sc->sc_rx_desc.rate,
 			    (flags & RT2573_RX_OFDM) ?
 			    IEEE80211_T_OFDM : IEEE80211_T_CCK);
+			rum_get_tsf(sc, &tap->wr_tsf);
 			tap->wr_antsignal = RT2573_NOISE_FLOOR + rssi;
 			tap->wr_antnoise = RT2573_NOISE_FLOOR;
 			tap->wr_antenna = sc->rx_ant;
@@ -1836,6 +1838,12 @@
 }
 
 static void
+rum_get_tsf(struct rum_softc *sc, uint64_t *buf)
+{
+	rum_read_multi(sc, RT2573_TXRX_CSR12, buf, sizeof (*buf));
+}
+
+static void
 rum_update_slot(struct rum_softc *sc)
 {
 	struct ieee80211com *ic = &sc->sc_ic;
Index: head/sys/dev/usb/wlan/if_rumvar.h
===================================================================
--- head/sys/dev/usb/wlan/if_rumvar.h
+++ head/sys/dev/usb/wlan/if_rumvar.h
@@ -22,6 +22,7 @@
 
 struct rum_rx_radiotap_header {
 	struct ieee80211_radiotap_header wr_ihdr;
+	uint64_t	wr_tsf;
 	uint8_t		wr_flags;
 	uint8_t		wr_rate;
 	uint16_t	wr_chan_freq;
@@ -32,7 +33,8 @@
 } __packed __aligned(8);
 
 #define RT2573_RX_RADIOTAP_PRESENT					\
-	((1 << IEEE80211_RADIOTAP_FLAGS) |				\
+	((1 << IEEE80211_RADIOTAP_TSFT) |				\
+	 (1 << IEEE80211_RADIOTAP_FLAGS) |				\
 	 (1 << IEEE80211_RADIOTAP_RATE) |				\
 	 (1 << IEEE80211_RADIOTAP_CHANNEL) |				\
 	 (1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL) |			\
@@ -42,6 +44,7 @@
 
 struct rum_tx_radiotap_header {
 	struct ieee80211_radiotap_header wt_ihdr;
+	uint64_t	wt_tsf;
 	uint8_t		wt_flags;
 	uint8_t		wt_rate;
 	uint16_t	wt_chan_freq;
@@ -50,7 +53,8 @@
 } __packed __aligned(8);
 
 #define RT2573_TX_RADIOTAP_PRESENT					\
-	((1 << IEEE80211_RADIOTAP_FLAGS) |				\
+	((1 << IEEE80211_RADIOTAP_TSFT) |				\
+	 (1 << IEEE80211_RADIOTAP_FLAGS) |				\
 	 (1 << IEEE80211_RADIOTAP_RATE) |				\
 	 (1 << IEEE80211_RADIOTAP_CHANNEL) |				\
 	 (1 << IEEE80211_RADIOTAP_ANTENNA))