ath5k: Adaptive Noise Immunity (ANI) Implementation

This is an Adaptive Noise Imunity (ANI) implementation for ath5k. I have looked
at both ath9k and HAL sources (they are nearly the same), and even though i
have implemented some things differently, the basic algorithm is practically
the same, for now. I hope that this can serve as a clean start to improve the
algorithm later.

This also adds a possibility to manually control ANI settings, right now only
thru a debugfs file:
  * set lowest sensitivity (=highest noise immunity):
	echo sens-low > /sys/kernel/debug/ath5k/phy0/ani
  * set highest sensitivity (=lowest noise immunity):
	echo sens-high > /sys/kernel/debug/ath5k/phy0/ani
  * automatically control immunity (default):
	echo ani-on > /sys/kernel/debug/ath5k/phy0/ani
  * to see the parameters in use and watch them change:
	cat /sys/kernel/debug/ath5k/phy0/ani

Manually setting sensitivity will turn the automatic control off. You can also
control each of the five immunity parameters (noise immunity, spur immunity,
firstep, ofdm weak signal detection, cck weak signal detection) manually thru
the debugfs file.

This is tested on AR5414 and nearly doubles the thruput in a noisy 2GHz band.

Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 744 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/ath5k/ani.c b/drivers/net/wireless/ath/ath5k/ani.c
new file mode 100644
index 000000000000..584a32859bdb
--- /dev/null
+++ b/drivers/net/wireless/ath/ath5k/ani.c
@@ -0,0 +1,744 @@
+/*
+ * Copyright (C) 2010 Bruno Randolf <br1@einfach.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "ath5k.h"
+#include "base.h"
+#include "reg.h"
+#include "debug.h"
+#include "ani.h"
+
+/**
+ * DOC: Basic ANI Operation
+ *
+ * Adaptive Noise Immunity (ANI) controls five noise immunity parameters
+ * depending on the amount of interference in the environment, increasing
+ * or reducing sensitivity as necessary.
+ *
+ * The parameters are:
+ *   - "noise immunity"
+ *   - "spur immunity"
+ *   - "firstep level"
+ *   - "OFDM weak signal detection"
+ *   - "CCK weak signal detection"
+ *
+ * Basically we look at the amount of ODFM and CCK timing errors we get and then
+ * raise or lower immunity accordingly by setting one or more of these
+ * parameters.
+ * Newer chipsets have PHY error counters in hardware which will generate a MIB
+ * interrupt when they overflow. Older hardware has too enable PHY error frames
+ * by setting a RX flag and then count every single PHY error. When a specified
+ * threshold of errors has been reached we will raise immunity.
+ * Also we regularly check the amount of errors and lower or raise immunity as
+ * necessary.
+ */
+
+
+/*** ANI parameter control ***/
+
+/**
+ * ath5k_ani_set_noise_immunity_level() - Set noise immunity level
+ *
+ * @level: level between 0 and @ATH5K_ANI_MAX_NOISE_IMM_LVL
+ */
+void
+ath5k_ani_set_noise_immunity_level(struct ath5k_hw *ah, int level)
+{
+	/* TODO:
+	 * ANI documents suggest the following five levels to use, but the HAL
+	 * and ath9k use only use the last two levels, making this
+	 * essentially an on/off option. There *may* be a reason for this (???),
+	 * so i stick with the HAL version for now...
+	 */
+#if 0
+	const s8 hi[] = { -18, -18, -16, -14, -12 };
+	const s8 lo[] = { -52, -56, -60, -64, -70 };
+	const s8 sz[] = { -34, -41, -48, -55, -62 };
+	const s8 fr[] = { -70, -72, -75, -78, -80 };
+#else
+	const s8 sz[] = { -55, -62 };
+	const s8 lo[] = { -64, -70 };
+	const s8 hi[] = { -14, -12 };
+	const s8 fr[] = { -78, -80 };
+#endif
+	if (level < 0 || level > ARRAY_SIZE(sz)) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+			"level out of range %d", level);
+		return;
+	}
+
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_DESIRED_SIZE,
+				AR5K_PHY_DESIRED_SIZE_TOT, sz[level]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_AGCCOARSE,
+				AR5K_PHY_AGCCOARSE_LO, lo[level]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_AGCCOARSE,
+				AR5K_PHY_AGCCOARSE_HI, hi[level]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_SIG,
+				AR5K_PHY_SIG_FIRPWR, fr[level]);
+
+	ah->ah_sc->ani_state.noise_imm_level = level;
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "new level %d", level);
+}
+
+
+/**
+ * ath5k_ani_set_spur_immunity_level() - Set spur immunity level
+ *
+ * @level: level between 0 and @max_spur_level (the maximum level is dependent
+ *	on the chip revision).
+ */
+void
+ath5k_ani_set_spur_immunity_level(struct ath5k_hw *ah, int level)
+{
+	const int val[] = { 2, 4, 6, 8, 10, 12, 14, 16 };
+
+	if (level < 0 || level > ARRAY_SIZE(val) ||
+	    level > ah->ah_sc->ani_state.max_spur_level) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+			"level out of range %d", level);
+		return;
+	}
+
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_OFDM_SELFCORR,
+		AR5K_PHY_OFDM_SELFCORR_CYPWR_THR1, val[level]);
+
+	ah->ah_sc->ani_state.spur_level = level;
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "new level %d", level);
+}
+
+
+/**
+ * ath5k_ani_set_firstep_level() - Set "firstep" level
+ *
+ * @level: level between 0 and @ATH5K_ANI_MAX_FIRSTEP_LVL
+ */
+void
+ath5k_ani_set_firstep_level(struct ath5k_hw *ah, int level)
+{
+	const int val[] = { 0, 4, 8 };
+
+	if (level < 0 || level > ARRAY_SIZE(val)) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+			"level out of range %d", level);
+		return;
+	}
+
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_SIG,
+				AR5K_PHY_SIG_FIRSTEP, val[level]);
+
+	ah->ah_sc->ani_state.firstep_level = level;
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "new level %d", level);
+}
+
+
+/**
+ * ath5k_ani_set_ofdm_weak_signal_detection() - Control OFDM weak signal
+ *						detection
+ *
+ * @on: turn on or off
+ */
+void
+ath5k_ani_set_ofdm_weak_signal_detection(struct ath5k_hw *ah, bool on)
+{
+	const int m1l[] = { 127, 50 };
+	const int m2l[] = { 127, 40 };
+	const int m1[] = { 127, 0x4d };
+	const int m2[] = { 127, 0x40 };
+	const int m2cnt[] = { 31, 16 };
+	const int m2lcnt[] = { 63, 48 };
+
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_WEAK_OFDM_LOW_THR,
+				AR5K_PHY_WEAK_OFDM_LOW_THR_M1, m1l[on]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_WEAK_OFDM_LOW_THR,
+				AR5K_PHY_WEAK_OFDM_LOW_THR_M2, m2l[on]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_WEAK_OFDM_HIGH_THR,
+				AR5K_PHY_WEAK_OFDM_HIGH_THR_M1, m1[on]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_WEAK_OFDM_HIGH_THR,
+				AR5K_PHY_WEAK_OFDM_HIGH_THR_M2, m2[on]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_WEAK_OFDM_HIGH_THR,
+			AR5K_PHY_WEAK_OFDM_HIGH_THR_M2_COUNT, m2cnt[on]);
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_WEAK_OFDM_LOW_THR,
+			AR5K_PHY_WEAK_OFDM_LOW_THR_M2_COUNT, m2lcnt[on]);
+
+	if (on)
+		AR5K_REG_ENABLE_BITS(ah, AR5K_PHY_WEAK_OFDM_LOW_THR,
+				AR5K_PHY_WEAK_OFDM_LOW_THR_SELFCOR_EN);
+	else
+		AR5K_REG_DISABLE_BITS(ah, AR5K_PHY_WEAK_OFDM_LOW_THR,
+				AR5K_PHY_WEAK_OFDM_LOW_THR_SELFCOR_EN);
+
+	ah->ah_sc->ani_state.ofdm_weak_sig = on;
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "turned %s",
+			  on ? "on" : "off");
+}
+
+
+/**
+ * ath5k_ani_set_cck_weak_signal_detection() - control CCK weak signal detection
+ *
+ * @on: turn on or off
+ */
+void
+ath5k_ani_set_cck_weak_signal_detection(struct ath5k_hw *ah, bool on)
+{
+	const int val[] = { 8, 6 };
+	AR5K_REG_WRITE_BITS(ah, AR5K_PHY_CCK_CROSSCORR,
+				AR5K_PHY_CCK_CROSSCORR_WEAK_SIG_THR, val[on]);
+	ah->ah_sc->ani_state.cck_weak_sig = on;
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "turned %s",
+			  on ? "on" : "off");
+}
+
+
+/*** ANI algorithm ***/
+
+/**
+ * ath5k_ani_raise_immunity() - Increase noise immunity
+ *
+ * @ofdm_trigger: If this is true we are called because of too many OFDM errors,
+ *	the algorithm will tune more parameters then.
+ *
+ * Try to raise noise immunity (=decrease sensitivity) in several steps
+ * depending on the average RSSI of the beacons we received.
+ */
+static void
+ath5k_ani_raise_immunity(struct ath5k_hw *ah, struct ath5k_ani_state *as,
+			 bool ofdm_trigger)
+{
+	int rssi = ah->ah_beacon_rssi_avg.avg;
+
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "raise immunity (%s)",
+		ofdm_trigger ? "ODFM" : "CCK");
+
+	/* first: raise noise immunity */
+	if (as->noise_imm_level < ATH5K_ANI_MAX_NOISE_IMM_LVL) {
+		ath5k_ani_set_noise_immunity_level(ah, as->noise_imm_level + 1);
+		return;
+	}
+
+	/* only OFDM: raise spur immunity level */
+	if (ofdm_trigger &&
+	    as->spur_level < ah->ah_sc->ani_state.max_spur_level) {
+		ath5k_ani_set_spur_immunity_level(ah, as->spur_level + 1);
+		return;
+	}
+
+	/* AP mode */
+	if (ah->ah_sc->opmode == NL80211_IFTYPE_AP) {
+		if (as->firstep_level < ATH5K_ANI_MAX_FIRSTEP_LVL)
+			ath5k_ani_set_firstep_level(ah, as->firstep_level + 1);
+		return;
+	}
+
+	/* STA and IBSS mode */
+
+	/* TODO: for IBSS mode it would be better to keep a beacon RSSI average
+	 * per each neighbour node and use the minimum of these, to make sure we
+	 * don't shut out a remote node by raising immunity too high. */
+
+	if (rssi > ATH5K_ANI_RSSI_THR_HIGH) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+				  "beacon RSSI high");
+		/* only OFDM: beacon RSSI is high, we can disable ODFM weak
+		 * signal detection */
+		if (ofdm_trigger && as->ofdm_weak_sig == true) {
+			ath5k_ani_set_ofdm_weak_signal_detection(ah, false);
+			ath5k_ani_set_spur_immunity_level(ah, 0);
+			return;
+		}
+		/* as a last resort or CCK: raise firstep level */
+		if (as->firstep_level < ATH5K_ANI_MAX_FIRSTEP_LVL) {
+			ath5k_ani_set_firstep_level(ah, as->firstep_level + 1);
+			return;
+		}
+	} else if (rssi > ATH5K_ANI_RSSI_THR_LOW) {
+		/* beacon RSSI in mid range, we need OFDM weak signal detect,
+		 * but can raise firstep level */
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+				  "beacon RSSI mid");
+		if (ofdm_trigger && as->ofdm_weak_sig == false)
+			ath5k_ani_set_ofdm_weak_signal_detection(ah, true);
+		if (as->firstep_level < ATH5K_ANI_MAX_FIRSTEP_LVL)
+			ath5k_ani_set_firstep_level(ah, as->firstep_level + 1);
+		return;
+	} else if (ah->ah_current_channel->band == IEEE80211_BAND_2GHZ) {
+		/* beacon RSSI is low. in B/G mode turn of OFDM weak signal
+		 * detect and zero firstep level to maximize CCK sensitivity */
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+				  "beacon RSSI low, 2GHz");
+		if (ofdm_trigger && as->ofdm_weak_sig == true)
+			ath5k_ani_set_ofdm_weak_signal_detection(ah, false);
+		if (as->firstep_level > 0)
+			ath5k_ani_set_firstep_level(ah, 0);
+		return;
+	}
+
+	/* TODO: why not?:
+	if (as->cck_weak_sig == true) {
+		ath5k_ani_set_cck_weak_signal_detection(ah, false);
+	}
+	*/
+}
+
+
+/**
+ * ath5k_ani_lower_immunity() - Decrease noise immunity
+ *
+ * Try to lower noise immunity (=increase sensitivity) in several steps
+ * depending on the average RSSI of the beacons we received.
+ */
+static void
+ath5k_ani_lower_immunity(struct ath5k_hw *ah, struct ath5k_ani_state *as)
+{
+	int rssi = ah->ah_beacon_rssi_avg.avg;
+
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "lower immunity");
+
+	if (ah->ah_sc->opmode == NL80211_IFTYPE_AP) {
+		/* AP mode */
+		if (as->firstep_level > 0) {
+			ath5k_ani_set_firstep_level(ah, as->firstep_level - 1);
+			return;
+		}
+	} else {
+		/* STA and IBSS mode (see TODO above) */
+		if (rssi > ATH5K_ANI_RSSI_THR_HIGH) {
+			/* beacon signal is high, leave OFDM weak signal
+			 * detection off or it may oscillate
+			 * TODO: who said it's off??? */
+		} else if (rssi > ATH5K_ANI_RSSI_THR_LOW) {
+			/* beacon RSSI is mid-range: turn on ODFM weak signal
+			 * detection and next, lower firstep level */
+			if (as->ofdm_weak_sig == false) {
+				ath5k_ani_set_ofdm_weak_signal_detection(ah,
+									 true);
+				return;
+			}
+			if (as->firstep_level > 0) {
+				ath5k_ani_set_firstep_level(ah,
+							as->firstep_level - 1);
+				return;
+			}
+		} else {
+			/* beacon signal is low: only reduce firstep level */
+			if (as->firstep_level > 0) {
+				ath5k_ani_set_firstep_level(ah,
+							as->firstep_level - 1);
+				return;
+			}
+		}
+	}
+
+	/* all modes */
+	if (as->spur_level > 0) {
+		ath5k_ani_set_spur_immunity_level(ah, as->spur_level - 1);
+		return;
+	}
+
+	/* finally, reduce noise immunity */
+	if (as->noise_imm_level > 0) {
+		ath5k_ani_set_noise_immunity_level(ah, as->noise_imm_level - 1);
+		return;
+	}
+}
+
+
+/**
+ * ath5k_hw_ani_get_listen_time() - Calculate time spent listening
+ *
+ * Return an approximation of the time spent "listening" in milliseconds (ms)
+ * since the last call of this function by deducting the cycles spent
+ * transmitting and receiving from the total cycle count.
+ * Save profile count values for debugging/statistics and because we might want
+ * to use them later.
+ *
+ * We assume no one else clears these registers!
+ */
+static int
+ath5k_hw_ani_get_listen_time(struct ath5k_hw *ah, struct ath5k_ani_state *as)
+{
+	int listen;
+
+	/* freeze */
+	ath5k_hw_reg_write(ah, AR5K_MIBC_FMC, AR5K_MIBC);
+	/* read */
+	as->pfc_cycles = ath5k_hw_reg_read(ah, AR5K_PROFCNT_CYCLE);
+	as->pfc_busy = ath5k_hw_reg_read(ah, AR5K_PROFCNT_RXCLR);
+	as->pfc_tx = ath5k_hw_reg_read(ah, AR5K_PROFCNT_TX);
+	as->pfc_rx = ath5k_hw_reg_read(ah, AR5K_PROFCNT_RX);
+	/* clear */
+	ath5k_hw_reg_write(ah, 0, AR5K_PROFCNT_TX);
+	ath5k_hw_reg_write(ah, 0, AR5K_PROFCNT_RX);
+	ath5k_hw_reg_write(ah, 0, AR5K_PROFCNT_RXCLR);
+	ath5k_hw_reg_write(ah, 0, AR5K_PROFCNT_CYCLE);
+	/* un-freeze */
+	ath5k_hw_reg_write(ah, 0, AR5K_MIBC);
+
+	/* TODO: where does 44000 come from? (11g clock rate?) */
+	listen = (as->pfc_cycles - as->pfc_rx - as->pfc_tx) / 44000;
+
+	if (as->pfc_cycles == 0 || listen < 0)
+		return 0;
+	return listen;
+}
+
+
+/**
+ * ath5k_ani_save_and_clear_phy_errors() - Clear and save PHY error counters
+ *
+ * Clear the PHY error counters as soon as possible, since this might be called
+ * from a MIB interrupt and we want to make sure we don't get interrupted again.
+ * Add the count of CCK and OFDM errors to our internal state, so it can be used
+ * by the algorithm later.
+ *
+ * Will be called from interrupt and tasklet context.
+ * Returns 0 if both counters are zero.
+ */
+static int
+ath5k_ani_save_and_clear_phy_errors(struct ath5k_hw *ah,
+				    struct ath5k_ani_state *as)
+{
+	unsigned int ofdm_err, cck_err;
+
+	if (!ah->ah_capabilities.cap_has_phyerr_counters)
+		return 0;
+
+	ofdm_err = ath5k_hw_reg_read(ah, AR5K_PHYERR_CNT1);
+	cck_err = ath5k_hw_reg_read(ah, AR5K_PHYERR_CNT2);
+
+	/* reset counters first, we might be in a hurry (interrupt) */
+	ath5k_hw_reg_write(ah, ATH5K_PHYERR_CNT_MAX - ATH5K_ANI_OFDM_TRIG_HIGH,
+			   AR5K_PHYERR_CNT1);
+	ath5k_hw_reg_write(ah, ATH5K_PHYERR_CNT_MAX - ATH5K_ANI_CCK_TRIG_HIGH,
+			   AR5K_PHYERR_CNT2);
+
+	ofdm_err = ATH5K_ANI_OFDM_TRIG_HIGH - (ATH5K_PHYERR_CNT_MAX - ofdm_err);
+	cck_err = ATH5K_ANI_CCK_TRIG_HIGH - (ATH5K_PHYERR_CNT_MAX - cck_err);
+
+	/* sometimes both can be zero, especially when there is a superfluous
+	 * second interrupt. detect that here and return an error. */
+	if (ofdm_err <= 0 && cck_err <= 0)
+		return 0;
+
+	/* avoid negative values should one of the registers overflow */
+	if (ofdm_err > 0) {
+		as->ofdm_errors += ofdm_err;
+		as->sum_ofdm_errors += ofdm_err;
+	}
+	if (cck_err > 0) {
+		as->cck_errors += cck_err;
+		as->sum_cck_errors += cck_err;
+	}
+	return 1;
+}
+
+
+/**
+ * ath5k_ani_period_restart() - Restart ANI period
+ *
+ * Just reset counters, so they are clear for the next "ani period".
+ */
+static void
+ath5k_ani_period_restart(struct ath5k_hw *ah, struct ath5k_ani_state *as)
+{
+	/* keep last values for debugging */
+	as->last_ofdm_errors = as->ofdm_errors;
+	as->last_cck_errors = as->cck_errors;
+	as->last_listen = as->listen_time;
+
+	as->ofdm_errors = 0;
+	as->cck_errors = 0;
+	as->listen_time = 0;
+}
+
+
+/**
+ * ath5k_ani_calibration() - The main ANI calibration function
+ *
+ * We count OFDM and CCK errors relative to the time where we did not send or
+ * receive ("listen" time) and raise or lower immunity accordingly.
+ * This is called regularly (every second) from the calibration timer, but also
+ * when an error threshold has been reached.
+ *
+ * In order to synchronize access from different contexts, this should be
+ * called only indirectly by scheduling the ANI tasklet!
+ */
+void
+ath5k_ani_calibration(struct ath5k_hw *ah)
+{
+	struct ath5k_ani_state *as = &ah->ah_sc->ani_state;
+	int listen, ofdm_high, ofdm_low, cck_high, cck_low;
+
+	if (as->ani_mode != ATH5K_ANI_MODE_AUTO)
+		return;
+
+	/* get listen time since last call and add it to the counter because we
+	 * might not have restarted the "ani period" last time */
+	listen = ath5k_hw_ani_get_listen_time(ah, as);
+	as->listen_time += listen;
+
+	ath5k_ani_save_and_clear_phy_errors(ah, as);
+
+	ofdm_high = as->listen_time * ATH5K_ANI_OFDM_TRIG_HIGH / 1000;
+	cck_high = as->listen_time * ATH5K_ANI_CCK_TRIG_HIGH / 1000;
+	ofdm_low = as->listen_time * ATH5K_ANI_OFDM_TRIG_LOW / 1000;
+	cck_low = as->listen_time * ATH5K_ANI_CCK_TRIG_LOW / 1000;
+
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+		"listen %d (now %d)", as->listen_time, listen);
+	ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+		"check high ofdm %d/%d cck %d/%d",
+		as->ofdm_errors, ofdm_high, as->cck_errors, cck_high);
+
+	if (as->ofdm_errors > ofdm_high || as->cck_errors > cck_high) {
+		/* too many PHY errors - we have to raise immunity */
+		bool ofdm_flag = as->ofdm_errors > ofdm_high ? true : false;
+		ath5k_ani_raise_immunity(ah, as, ofdm_flag);
+		ath5k_ani_period_restart(ah, as);
+
+	} else if (as->listen_time > 5 * ATH5K_ANI_LISTEN_PERIOD) {
+		/* If more than 5 (TODO: why 5?) periods have passed and we got
+		 * relatively little errors we can try to lower immunity */
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+			"check low ofdm %d/%d cck %d/%d",
+			as->ofdm_errors, ofdm_low, as->cck_errors, cck_low);
+
+		if (as->ofdm_errors <= ofdm_low && as->cck_errors <= cck_low)
+			ath5k_ani_lower_immunity(ah, as);
+
+		ath5k_ani_period_restart(ah, as);
+	}
+}
+
+
+/*** INTERRUPT HANDLER ***/
+
+/**
+ * ath5k_ani_mib_intr() - Interrupt handler for ANI MIB counters
+ *
+ * Just read & reset the registers quickly, so they don't generate more
+ * interrupts, save the counters and schedule the tasklet to decide whether
+ * to raise immunity or not.
+ *
+ * We just need to handle PHY error counters, ath5k_hw_update_mib_counters()
+ * should take care of all "normal" MIB interrupts.
+ */
+void
+ath5k_ani_mib_intr(struct ath5k_hw *ah)
+{
+	struct ath5k_ani_state *as = &ah->ah_sc->ani_state;
+
+	/* nothing to do here if HW does not have PHY error counters - they
+	 * can't be the reason for the MIB interrupt then */
+	if (!ah->ah_capabilities.cap_has_phyerr_counters)
+		return;
+
+	/* not in use but clear anyways */
+	ath5k_hw_reg_write(ah, 0, AR5K_OFDM_FIL_CNT);
+	ath5k_hw_reg_write(ah, 0, AR5K_CCK_FIL_CNT);
+
+	if (ah->ah_sc->ani_state.ani_mode != ATH5K_ANI_MODE_AUTO)
+		return;
+
+	/* if one of the errors triggered, we can get a superfluous second
+	 * interrupt, even though we have already reset the register. the
+	 * function detects that so we can return early */
+	if (ath5k_ani_save_and_clear_phy_errors(ah, as) == 0)
+		return;
+
+	if (as->ofdm_errors > ATH5K_ANI_OFDM_TRIG_HIGH ||
+	    as->cck_errors > ATH5K_ANI_CCK_TRIG_HIGH)
+		tasklet_schedule(&ah->ah_sc->ani_tasklet);
+}
+
+
+/**
+ * ath5k_ani_phy_error_report() - Used by older HW to report PHY errors
+ *
+ * This is used by hardware without PHY error counters to report PHY errors
+ * on a frame-by-frame basis, instead of the interrupt.
+ */
+void
+ath5k_ani_phy_error_report(struct ath5k_hw *ah,
+			   enum ath5k_phy_error_code phyerr)
+{
+	struct ath5k_ani_state *as = &ah->ah_sc->ani_state;
+
+	if (phyerr == AR5K_RX_PHY_ERROR_OFDM_TIMING) {
+		as->ofdm_errors++;
+		if (as->ofdm_errors > ATH5K_ANI_OFDM_TRIG_HIGH)
+			tasklet_schedule(&ah->ah_sc->ani_tasklet);
+	} else if (phyerr == AR5K_RX_PHY_ERROR_CCK_TIMING) {
+		as->cck_errors++;
+		if (as->cck_errors > ATH5K_ANI_CCK_TRIG_HIGH)
+			tasklet_schedule(&ah->ah_sc->ani_tasklet);
+	}
+}
+
+
+/*** INIT ***/
+
+/**
+ * ath5k_enable_phy_err_counters() - Enable PHY error counters
+ *
+ * Enable PHY error counters for OFDM and CCK timing errors.
+ */
+static void
+ath5k_enable_phy_err_counters(struct ath5k_hw *ah)
+{
+	ath5k_hw_reg_write(ah, ATH5K_PHYERR_CNT_MAX - ATH5K_ANI_OFDM_TRIG_HIGH,
+			   AR5K_PHYERR_CNT1);
+	ath5k_hw_reg_write(ah, ATH5K_PHYERR_CNT_MAX - ATH5K_ANI_CCK_TRIG_HIGH,
+			   AR5K_PHYERR_CNT2);
+	ath5k_hw_reg_write(ah, AR5K_PHY_ERR_FIL_OFDM, AR5K_PHYERR_CNT1_MASK);
+	ath5k_hw_reg_write(ah, AR5K_PHY_ERR_FIL_CCK, AR5K_PHYERR_CNT2_MASK);
+
+	/* not in use */
+	ath5k_hw_reg_write(ah, 0, AR5K_OFDM_FIL_CNT);
+	ath5k_hw_reg_write(ah, 0, AR5K_CCK_FIL_CNT);
+}
+
+
+/**
+ * ath5k_disable_phy_err_counters() - Disable PHY error counters
+ *
+ * Disable PHY error counters for OFDM and CCK timing errors.
+ */
+static void
+ath5k_disable_phy_err_counters(struct ath5k_hw *ah)
+{
+	ath5k_hw_reg_write(ah, 0, AR5K_PHYERR_CNT1);
+	ath5k_hw_reg_write(ah, 0, AR5K_PHYERR_CNT2);
+	ath5k_hw_reg_write(ah, 0, AR5K_PHYERR_CNT1_MASK);
+	ath5k_hw_reg_write(ah, 0, AR5K_PHYERR_CNT2_MASK);
+
+	/* not in use */
+	ath5k_hw_reg_write(ah, 0, AR5K_OFDM_FIL_CNT);
+	ath5k_hw_reg_write(ah, 0, AR5K_CCK_FIL_CNT);
+}
+
+
+/**
+ * ath5k_ani_init() - Initialize ANI
+ * @mode: Which mode to use (auto, manual high, manual low, off)
+ *
+ * Initialize ANI according to mode.
+ */
+void
+ath5k_ani_init(struct ath5k_hw *ah, enum ath5k_ani_mode mode)
+{
+	/* ANI is only possible on 5212 and newer */
+	if (ah->ah_version < AR5K_AR5212)
+		return;
+
+	/* clear old state information */
+	memset(&ah->ah_sc->ani_state, 0, sizeof(ah->ah_sc->ani_state));
+
+	/* older hardware has more spur levels than newer */
+	if (ah->ah_mac_srev < AR5K_SREV_AR2414)
+		ah->ah_sc->ani_state.max_spur_level = 7;
+	else
+		ah->ah_sc->ani_state.max_spur_level = 2;
+
+	/* initial values for our ani parameters */
+	if (mode == ATH5K_ANI_MODE_OFF) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "ANI off\n");
+	} else if  (mode == ATH5K_ANI_MODE_MANUAL_LOW) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+			"ANI manual low -> high sensitivity\n");
+		ath5k_ani_set_noise_immunity_level(ah, 0);
+		ath5k_ani_set_spur_immunity_level(ah, 0);
+		ath5k_ani_set_firstep_level(ah, 0);
+		ath5k_ani_set_ofdm_weak_signal_detection(ah, true);
+		ath5k_ani_set_cck_weak_signal_detection(ah, true);
+	} else if (mode == ATH5K_ANI_MODE_MANUAL_HIGH) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI,
+			"ANI manual high -> low sensitivity\n");
+		ath5k_ani_set_noise_immunity_level(ah,
+					ATH5K_ANI_MAX_NOISE_IMM_LVL);
+		ath5k_ani_set_spur_immunity_level(ah,
+					ah->ah_sc->ani_state.max_spur_level);
+		ath5k_ani_set_firstep_level(ah, ATH5K_ANI_MAX_FIRSTEP_LVL);
+		ath5k_ani_set_ofdm_weak_signal_detection(ah, false);
+		ath5k_ani_set_cck_weak_signal_detection(ah, false);
+	} else if (mode == ATH5K_ANI_MODE_AUTO) {
+		ATH5K_DBG_UNLIMIT(ah->ah_sc, ATH5K_DEBUG_ANI, "ANI auto\n");
+		ath5k_ani_set_noise_immunity_level(ah, 0);
+		ath5k_ani_set_spur_immunity_level(ah, 0);
+		ath5k_ani_set_firstep_level(ah, 0);
+		ath5k_ani_set_ofdm_weak_signal_detection(ah, true);
+		ath5k_ani_set_cck_weak_signal_detection(ah, false);
+	}
+
+	/* newer hardware has PHY error counter registers which we can use to
+	 * get OFDM and CCK error counts. older hardware has to set rxfilter and
+	 * report every single PHY error by calling ath5k_ani_phy_error_report()
+	 */
+	if (mode == ATH5K_ANI_MODE_AUTO) {
+		if (ah->ah_capabilities.cap_has_phyerr_counters)
+			ath5k_enable_phy_err_counters(ah);
+		else
+			ath5k_hw_set_rx_filter(ah, ath5k_hw_get_rx_filter(ah) |
+						   AR5K_RX_FILTER_PHYERR);
+	} else {
+		if (ah->ah_capabilities.cap_has_phyerr_counters)
+			ath5k_disable_phy_err_counters(ah);
+		else
+			ath5k_hw_set_rx_filter(ah, ath5k_hw_get_rx_filter(ah) &
+						   ~AR5K_RX_FILTER_PHYERR);
+	}
+
+	ah->ah_sc->ani_state.ani_mode = mode;
+}
+
+
+/*** DEBUG ***/
+
+#ifdef CONFIG_ATH5K_DEBUG
+
+void
+ath5k_ani_print_counters(struct ath5k_hw *ah)
+{
+	/* clears too */
+	printk(KERN_NOTICE "ACK fail\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_ACK_FAIL));
+	printk(KERN_NOTICE "RTS fail\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_RTS_FAIL));
+	printk(KERN_NOTICE "RTS success\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_RTS_OK));
+	printk(KERN_NOTICE "FCS error\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_FCS_FAIL));
+
+	/* no clear */
+	printk(KERN_NOTICE "tx\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_PROFCNT_TX));
+	printk(KERN_NOTICE "rx\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_PROFCNT_RX));
+	printk(KERN_NOTICE "busy\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_PROFCNT_RXCLR));
+	printk(KERN_NOTICE "cycles\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_PROFCNT_CYCLE));
+
+	printk(KERN_NOTICE "AR5K_PHYERR_CNT1\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_PHYERR_CNT1));
+	printk(KERN_NOTICE "AR5K_PHYERR_CNT2\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_PHYERR_CNT2));
+	printk(KERN_NOTICE "AR5K_OFDM_FIL_CNT\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_OFDM_FIL_CNT));
+	printk(KERN_NOTICE "AR5K_CCK_FIL_CNT\t%d\n",
+		ath5k_hw_reg_read(ah, AR5K_CCK_FIL_CNT));
+}
+
+#endif