ath9k: enable ANI to help with noisy environments

This enables Adaptive Noise Immunity (ANI) on ath9k.
ANI is as algorithm designed to minimize the detrimental
effects of time-varying interferences. This should
help with throughput in noisy environments. To use
ANI we re-enable the MIB interrupt. Since ANI works
on a timer and updates the noise floor we take
advantage of this and also report a non-static noise
floor now to mac80211.

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: Jouni Malinen <Jouni.Malinen@Atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 122 insertions, 7 deletions

diff --git a/drivers/net/wireless/ath9k/core.c b/drivers/net/wireless/ath9k/core.c
index 5af7dfb..c5033f6 100644
--- a/drivers/net/wireless/ath9k/core.c
+++ b/drivers/net/wireless/ath9k/core.c
@@ -490,6 +490,122 @@ void ath_update_chainmask(struct ath_softc *sc, int is_ht)
 		__func__, sc->sc_tx_chainmask, sc->sc_rx_chainmask);
 }
 
+/*******/
+/* ANI */
+/*******/
+
+/*
+ *  This routine performs the periodic noise floor calibration function
+ *  that is used to adjust and optimize the chip performance.  This
+ *  takes environmental changes (location, temperature) into account.
+ *  When the task is complete, it reschedules itself depending on the
+ *  appropriate interval that was calculated.
+ */
+
+static void ath_ani_calibrate(unsigned long data)
+{
+	struct ath_softc *sc;
+	struct ath_hal *ah;
+	bool longcal = false;
+	bool shortcal = false;
+	bool aniflag = false;
+	unsigned int timestamp = jiffies_to_msecs(jiffies);
+	u32 cal_interval;
+
+	sc = (struct ath_softc *)data;
+	ah = sc->sc_ah;
+
+	/*
+	* don't calibrate when we're scanning.
+	* we are most likely not on our home channel.
+	*/
+	if (sc->rx_filter & FIF_BCN_PRBRESP_PROMISC)
+		return;
+
+	/* Long calibration runs independently of short calibration. */
+	if ((timestamp - sc->sc_ani.sc_longcal_timer) >= ATH_LONG_CALINTERVAL) {
+		longcal = true;
+		DPRINTF(sc, ATH_DBG_ANI, "%s: longcal @%lu\n",
+			__func__, jiffies);
+		sc->sc_ani.sc_longcal_timer = timestamp;
+	}
+
+	/* Short calibration applies only while sc_caldone is false */
+	if (!sc->sc_ani.sc_caldone) {
+		if ((timestamp - sc->sc_ani.sc_shortcal_timer) >=
+		    ATH_SHORT_CALINTERVAL) {
+			shortcal = true;
+			DPRINTF(sc, ATH_DBG_ANI, "%s: shortcal @%lu\n",
+			       __func__, jiffies);
+			sc->sc_ani.sc_shortcal_timer = timestamp;
+			sc->sc_ani.sc_resetcal_timer = timestamp;
+		}
+	} else {
+		if ((timestamp - sc->sc_ani.sc_resetcal_timer) >=
+		    ATH_RESTART_CALINTERVAL) {
+			ath9k_hw_reset_calvalid(ah, ah->ah_curchan,
+						&sc->sc_ani.sc_caldone);
+			if (sc->sc_ani.sc_caldone)
+				sc->sc_ani.sc_resetcal_timer = timestamp;
+		}
+	}
+
+	/* Verify whether we must check ANI */
+	if ((timestamp - sc->sc_ani.sc_checkani_timer) >=
+	   ATH_ANI_POLLINTERVAL) {
+		aniflag = true;
+		sc->sc_ani.sc_checkani_timer = timestamp;
+	}
+
+	/* Skip all processing if there's nothing to do. */
+	if (longcal || shortcal || aniflag) {
+		/* Call ANI routine if necessary */
+		if (aniflag)
+			ath9k_hw_ani_monitor(ah, &sc->sc_halstats,
+					     ah->ah_curchan);
+
+		/* Perform calibration if necessary */
+		if (longcal || shortcal) {
+			bool iscaldone = false;
+
+			if (ath9k_hw_calibrate(ah, ah->ah_curchan,
+					       sc->sc_rx_chainmask, longcal,
+					       &iscaldone)) {
+				if (longcal)
+					sc->sc_ani.sc_noise_floor =
+						ath9k_hw_getchan_noise(ah,
+							       ah->ah_curchan);
+
+				DPRINTF(sc, ATH_DBG_ANI,
+					"%s: calibrate chan %u/%x nf: %d\n",
+					 __func__,
+					ah->ah_curchan->channel,
+					ah->ah_curchan->channelFlags,
+					sc->sc_ani.sc_noise_floor);
+			} else {
+				DPRINTF(sc, ATH_DBG_ANY,
+					"%s: calibrate chan %u/%x failed\n",
+					 __func__,
+					ah->ah_curchan->channel,
+					ah->ah_curchan->channelFlags);
+			}
+			sc->sc_ani.sc_caldone = iscaldone;
+		}
+	}
+
+	/*
+	* Set timer interval based on previous results.
+	* The interval must be the shortest necessary to satisfy ANI,
+	* short calibration and long calibration.
+	*/
+
+	cal_interval = ATH_ANI_POLLINTERVAL;
+	if (!sc->sc_ani.sc_caldone)
+		cal_interval = min(cal_interval, (u32)ATH_SHORT_CALINTERVAL);
+
+	mod_timer(&sc->sc_ani.timer, jiffies + msecs_to_jiffies(cal_interval));
+}
+
 /******************/
 /* VAP management */
 /******************/
@@ -676,12 +792,6 @@ int ath_open(struct ath_softc *sc, struct ath9k_channel *initial_chan)
 	if (ah->ah_caps.hw_caps & ATH9K_HW_CAP_HT)
 		sc->sc_imask |= ATH9K_INT_CST;
 
-	/* Note: We disable MIB interrupts for now as we don't yet
-	 * handle processing ANI, otherwise you will get an interrupt
-	 * storm after about 7 hours of usage making the system unusable
-	 * with huge latency. Once we do have ANI processing included
-	 * we can re-enable this interrupt. */
-#if 0
 	/*
 	 * Enable MIB interrupts when there are hardware phy counters.
 	 * Note we only do this (at the moment) for station mode.
@@ -690,7 +800,6 @@ int ath_open(struct ath_softc *sc, struct ath9k_channel *initial_chan)
 	    ((sc->sc_ah->ah_opmode == ATH9K_M_STA) ||
 	     (sc->sc_ah->ah_opmode == ATH9K_M_IBSS)))
 		sc->sc_imask |= ATH9K_INT_MIB;
-#endif
 	/*
 	 * Some hardware processes the TIM IE and fires an
 	 * interrupt when the TIM bit is set.  For hardware
@@ -991,6 +1100,10 @@ int ath_init(u16 devid, struct ath_softc *sc)
 	}
 	sc->sc_ah = ah;
 
+	/* Initializes the noise floor to a reasonable default value.
+	 * Later on this will be updated during ANI processing. */
+	sc->sc_ani.sc_noise_floor = ATH_DEFAULT_NOISE_FLOOR;
+
 	/* Get the hardware key cache size. */
 	sc->sc_keymax = ah->ah_caps.keycache_size;
 	if (sc->sc_keymax > ATH_KEYMAX) {
@@ -1098,6 +1211,8 @@ int ath_init(u16 devid, struct ath_softc *sc)
 		goto bad2;
 	}
 
+	setup_timer(&sc->sc_ani.timer, ath_ani_calibrate, (unsigned long)sc);
+
 	sc->sc_rc = ath_rate_attach(ah);
 	if (sc->sc_rc == NULL) {
 		error = -EIO;