drivers/net/wireless/rt2x00/rt2x00link.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
 	Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
 	<http://rt2x00.serialmonkey.com>

 	This program is free software; you can redistribute it and/or modify
 	it under the terms of the GNU General Public License as published by
 	the Free Software Foundation; either version 2 of the License, or
 	(at your option) any later version.

 	This program is distributed in the hope that it will be useful,
 	but WITHOUT ANY WARRANTY; without even the implied warranty of
 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 	GNU General Public License for more details.

 	You should have received a copy of the GNU General Public License
 	along with this program; if not, write to the
 	Free Software Foundation, Inc.,
 	59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */

 /*
 	Module: rt2x00lib
 	Abstract: rt2x00 generic link tuning routines.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>

 #include "rt2x00.h"
 #include "rt2x00lib.h"

 /*
  * When we lack RSSI information return something less then -80 to
  * tell the driver to tune the device to maximum sensitivity.
  */
 #define DEFAULT_RSSI		-128

 /*
  * Helper struct and macro to work with moving/walking averages.
  * When adding a value to the average value the following calculation
  * is needed:
  *
  *        avg_rssi = ((avg_rssi * 7) + rssi) / 8;
  *
  * The advantage of this approach is that we only need 1 variable
  * to store the average in (No need for a count and a total).
  * But more importantly, normal average values will over time
  * move less and less towards newly added values this results
  * that with link tuning, the device can have a very good RSSI
  * for a few minutes but when the device is moved away from the AP
  * the average will not decrease fast enough to compensate.
  * The walking average compensates this and will move towards
  * the new values correctly allowing a effective link tuning,
  * the speed of the average moving towards other values depends
  * on the value for the number of samples. The higher the number
  * of samples, the slower the average will move.
  * We use two variables to keep track of the average value to
  * compensate for the rounding errors. This can be a significant
  * error (>5dBm) if the factor is too low.
  */
 #define AVG_SAMPLES	8
 #define AVG_FACTOR	1000
 #define MOVING_AVERAGE(__avg, __val) \
 ({ \
 	struct avg_val __new; \
 	__new.avg_weight = \
 	    (__avg).avg_weight  ? \
 		((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \
 		  ((__val) * (AVG_FACTOR))) / \
 		 (AVG_SAMPLES)) : \
 		((__val) * (AVG_FACTOR)); \
 	__new.avg = __new.avg_weight / (AVG_FACTOR); \
 	__new; \
 })

 static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;

 	if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)
 		return ant->rssi_ant.avg;
 	return DEFAULT_RSSI;
 }

 static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;

 	if (ant->rssi_history)
 		return ant->rssi_history;
 	return DEFAULT_RSSI;
 }

 static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
 						   int rssi)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;
 	ant->rssi_history = rssi;
 }

 static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
 {
 	rt2x00dev->link.ant.rssi_ant.avg = 0;
 	rt2x00dev->link.ant.rssi_ant.avg_weight = 0;
 }

 static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;
 	struct antenna_setup new_ant;
 	int other_antenna;

 	int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
 	int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);

 	memcpy(&new_ant, &ant->active, sizeof(new_ant));

 	/*
 	 * We are done sampling. Now we should evaluate the results.
 	 */
 	ant->flags &= ~ANTENNA_MODE_SAMPLE;

 	/*
 	 * During the last period we have sampled the RSSI
 	 * from both antennas. It now is time to determine
 	 * which antenna demonstrated the best performance.
 	 * When we are already on the antenna with the best
 	 * performance, just create a good starting point
 	 * for the history and we are done.
 	 */
 	if (sample_current >= sample_other) {
 		rt2x00link_antenna_update_rssi_history(rt2x00dev,
 			sample_current);
 		return;
 	}

 	other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

 	if (ant->flags & ANTENNA_RX_DIVERSITY)
 		new_ant.rx = other_antenna;

 	if (ant->flags & ANTENNA_TX_DIVERSITY)
 		new_ant.tx = other_antenna;

 	rt2x00lib_config_antenna(rt2x00dev, new_ant);
 }

 static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;
 	struct antenna_setup new_ant;
 	int rssi_curr;
 	int rssi_old;

 	memcpy(&new_ant, &ant->active, sizeof(new_ant));

 	/*
 	 * Get current RSSI value along with the historical value,
 	 * after that update the history with the current value.
 	 */
 	rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
 	rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
 	rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);

 	/*
 	 * Legacy driver indicates that we should swap antenna's
 	 * when the difference in RSSI is greater that 5. This
 	 * also should be done when the RSSI was actually better
 	 * then the previous sample.
 	 * When the difference exceeds the threshold we should
 	 * sample the rssi from the other antenna to make a valid
 	 * comparison between the 2 antennas.
 	 */
 	if (abs(rssi_curr - rssi_old) < 5)
 		return;

 	ant->flags |= ANTENNA_MODE_SAMPLE;

 	if (ant->flags & ANTENNA_RX_DIVERSITY)
 		new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

 	if (ant->flags & ANTENNA_TX_DIVERSITY)
 		new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

 	rt2x00lib_config_antenna(rt2x00dev, new_ant);
 }

 static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;

 	/*
 	 * Determine if software diversity is enabled for
 	 * either the TX or RX antenna (or both).
 	 */
 	if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
 	    !(ant->flags & ANTENNA_TX_DIVERSITY)) {
 		ant->flags = 0;
 		return true;
 	}

 	/*
 	 * If we have only sampled the data over the last period
 	 * we should now harvest the data. Otherwise just evaluate
 	 * the data. The latter should only be performed once
 	 * every 2 seconds.
 	 */
 	if (ant->flags & ANTENNA_MODE_SAMPLE) {
 		rt2x00lib_antenna_diversity_sample(rt2x00dev);
 		return true;
 	} else if (rt2x00dev->link.count & 1) {
 		rt2x00lib_antenna_diversity_eval(rt2x00dev);
 		return true;
 	}

 	return false;
 }

 void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
 			     struct sk_buff *skb,
 			     struct rxdone_entry_desc *rxdesc)
 {
 	struct link *link = &rt2x00dev->link;
 	struct link_qual *qual = &rt2x00dev->link.qual;
 	struct link_ant *ant = &rt2x00dev->link.ant;
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

 	/*
 	 * No need to update the stats for !=STA interfaces
 	 */
 	if (!rt2x00dev->intf_sta_count)
 		return;

 	/*
 	 * Frame was received successfully since non-succesfull
 	 * frames would have been dropped by the hardware.
 	 */
 	qual->rx_success++;

 	/*
 	 * We are only interested in quality statistics from
 	 * beacons which came from the BSS which we are
 	 * associated with.
 	 */
 	if (!ieee80211_is_beacon(hdr->frame_control) ||
 	    !(rxdesc->dev_flags & RXDONE_MY_BSS))
 		return;

 	/*
 	 * Update global RSSI
 	 */
 	link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);

 	/*
 	 * Update antenna RSSI
 	 */
 	ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);
 }

 void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
 {
 	struct link *link = &rt2x00dev->link;

 	/*
 	 * Link tuning should only be performed when
 	 * an active sta interface exists. AP interfaces
 	 * don't need link tuning and monitor mode interfaces
 	 * should never have to work with link tuners.
 	 */
 	if (!rt2x00dev->intf_sta_count)
 		return;

 	/**
 	 * While scanning, link tuning is disabled. By default
 	 * the most sensitive settings will be used to make sure
 	 * that all beacons and probe responses will be received
 	 * during the scan.
 	 */
 	if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
 		return;

 	rt2x00link_reset_tuner(rt2x00dev, false);

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->work, LINK_TUNE_INTERVAL);
 }

 void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
 {
 	cancel_delayed_work_sync(&rt2x00dev->link.work);
 }

 void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
 {
 	struct link_qual *qual = &rt2x00dev->link.qual;
 	u8 vgc_level = qual->vgc_level_reg;

 	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;

 	/*
 	 * Reset link information.
 	 * Both the currently active vgc level as well as
 	 * the link tuner counter should be reset. Resetting
 	 * the counter is important for devices where the
 	 * device should only perform link tuning during the
 	 * first minute after being enabled.
 	 */
 	rt2x00dev->link.count = 0;
 	memset(qual, 0, sizeof(*qual));

 	/*
 	 * Restore the VGC level as stored in the registers,
 	 * the driver can use this to determine if the register
 	 * must be updated during reset or not.
 	 */
 	qual->vgc_level_reg = vgc_level;

 	/*
 	 * Reset the link tuner.
 	 */
 	rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);

 	if (antenna)
 		rt2x00link_antenna_reset(rt2x00dev);
 }

 static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_qual *qual = &rt2x00dev->link.qual;

 	qual->rx_success = 0;
 	qual->rx_failed = 0;
 	qual->tx_success = 0;
 	qual->tx_failed = 0;
 }

 static void rt2x00link_tuner(struct work_struct *work)
 {
 	struct rt2x00_dev *rt2x00dev =
 	    container_of(work, struct rt2x00_dev, link.work.work);
 	struct link *link = &rt2x00dev->link;
 	struct link_qual *qual = &rt2x00dev->link.qual;

 	/*
 	 * When the radio is shutting down we should
 	 * immediately cease all link tuning.
 	 */
 	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags) ||
 	    test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
 		return;

 	/*
 	 * Update statistics.
 	 */
 	rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
 	rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;

 	/*
 	 * Update quality RSSI for link tuning,
 	 * when we have received some frames and we managed to
 	 * collect the RSSI data we could use this. Otherwise we
 	 * must fallback to the default RSSI value.
 	 */
 	if (!link->avg_rssi.avg || !qual->rx_success)
 		qual->rssi = DEFAULT_RSSI;
 	else
 		qual->rssi = link->avg_rssi.avg;

 	/*
 	 * Check if link tuning is supported by the hardware, some hardware
 	 * do not support link tuning at all, while other devices can disable
 	 * the feature from the EEPROM.
 	 */
 	if (test_bit(CAPABILITY_LINK_TUNING, &rt2x00dev->cap_flags))
 		rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);

 	/*
 	 * Send a signal to the led to update the led signal strength.
 	 */
 	rt2x00leds_led_quality(rt2x00dev, qual->rssi);

 	/*
 	 * Evaluate antenna setup, make this the last step when
 	 * rt2x00lib_antenna_diversity made changes the quality
 	 * statistics will be reset.
 	 */
 	if (rt2x00lib_antenna_diversity(rt2x00dev))
 		rt2x00link_reset_qual(rt2x00dev);

 	/*
 	 * Increase tuner counter, and reschedule the next link tuner run.
 	 */
 	link->count++;

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->work, LINK_TUNE_INTERVAL);
 }

 void rt2x00link_start_watchdog(struct rt2x00_dev *rt2x00dev)
 {
 	struct link *link = &rt2x00dev->link;

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
 	    rt2x00dev->ops->lib->watchdog)
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->watchdog_work,
 					     WATCHDOG_INTERVAL);
 }

 void rt2x00link_stop_watchdog(struct rt2x00_dev *rt2x00dev)
 {
 	cancel_delayed_work_sync(&rt2x00dev->link.watchdog_work);
 }

 static void rt2x00link_watchdog(struct work_struct *work)
 {
 	struct rt2x00_dev *rt2x00dev =
 	    container_of(work, struct rt2x00_dev, link.watchdog_work.work);
 	struct link *link = &rt2x00dev->link;

 	/*
 	 * When the radio is shutting down we should
 	 * immediately cease the watchdog monitoring.
 	 */
 	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;

 	rt2x00dev->ops->lib->watchdog(rt2x00dev);

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->watchdog_work,
 					     WATCHDOG_INTERVAL);
 }

 void rt2x00link_start_agc(struct rt2x00_dev *rt2x00dev)
 {
 	struct link *link = &rt2x00dev->link;

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
 	    rt2x00dev->ops->lib->gain_calibration)
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->agc_work,
 					     AGC_INTERVAL);
 }

 void rt2x00link_start_vcocal(struct rt2x00_dev *rt2x00dev)
 {
 	struct link *link = &rt2x00dev->link;

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
 	    rt2x00dev->ops->lib->vco_calibration)
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->vco_work,
 					     VCO_INTERVAL);
 }

 void rt2x00link_stop_agc(struct rt2x00_dev *rt2x00dev)
 {
 	cancel_delayed_work_sync(&rt2x00dev->link.agc_work);
 }

 void rt2x00link_stop_vcocal(struct rt2x00_dev *rt2x00dev)
 {
 	cancel_delayed_work_sync(&rt2x00dev->link.vco_work);
 }

 static void rt2x00link_agc(struct work_struct *work)
 {
 	struct rt2x00_dev *rt2x00dev =
 	    container_of(work, struct rt2x00_dev, link.agc_work.work);
 	struct link *link = &rt2x00dev->link;

 	/*
 	 * When the radio is shutting down we should
 	 * immediately cease the watchdog monitoring.
 	 */
 	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;

 	rt2x00dev->ops->lib->gain_calibration(rt2x00dev);

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->agc_work,
 					     AGC_INTERVAL);
 }

 static void rt2x00link_vcocal(struct work_struct *work)
 {
 	struct rt2x00_dev *rt2x00dev =
 	    container_of(work, struct rt2x00_dev, link.vco_work.work);
 	struct link *link = &rt2x00dev->link;

 	/*
 	 * When the radio is shutting down we should
 	 * immediately cease the VCO calibration.
 	 */
 	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;

 	rt2x00dev->ops->lib->vco_calibration(rt2x00dev);

 	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
 		ieee80211_queue_delayed_work(rt2x00dev->hw,
 					     &link->vco_work,
 					     VCO_INTERVAL);
 }

 void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
 {
 	INIT_DELAYED_WORK(&rt2x00dev->link.agc_work, rt2x00link_agc);
 	if (test_bit(CAPABILITY_VCO_RECALIBRATION, &rt2x00dev->cap_flags))
 		INIT_DELAYED_WORK(&rt2x00dev->link.vco_work, rt2x00link_vcocal);
 	INIT_DELAYED_WORK(&rt2x00dev->link.watchdog_work, rt2x00link_watchdog);
 	INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
 }
	/*
	Copyright (C) 2004 - 2009 Ivo van Doorn <IvDoorn@gmail.com>
	<http://rt2x00.serialmonkey.com>

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the
	Free Software Foundation, Inc.,
	59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	*/

	/*
	Module: rt2x00lib
	Abstract: rt2x00 generic link tuning routines.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>

	#include "rt2x00.h"
	#include "rt2x00lib.h"

	/*
	* When we lack RSSI information return something less then -80 to
	* tell the driver to tune the device to maximum sensitivity.
	*/
	#define DEFAULT_RSSI -128

	/*
	* Helper struct and macro to work with moving/walking averages.
	* When adding a value to the average value the following calculation
	* is needed:
	*
	* avg_rssi = ((avg_rssi * 7) + rssi) / 8;
	*
	* The advantage of this approach is that we only need 1 variable
	* to store the average in (No need for a count and a total).
	* But more importantly, normal average values will over time
	* move less and less towards newly added values this results
	* that with link tuning, the device can have a very good RSSI
	* for a few minutes but when the device is moved away from the AP
	* the average will not decrease fast enough to compensate.
	* The walking average compensates this and will move towards
	* the new values correctly allowing a effective link tuning,
	* the speed of the average moving towards other values depends
	* on the value for the number of samples. The higher the number
	* of samples, the slower the average will move.
	* We use two variables to keep track of the average value to
	* compensate for the rounding errors. This can be a significant
	* error (>5dBm) if the factor is too low.
	*/
	#define AVG_SAMPLES 8
	#define AVG_FACTOR 1000
	#define MOVING_AVERAGE(__avg, __val) \
	({ \
	struct avg_val __new; \
	__new.avg_weight = \
	(__avg).avg_weight ? \
	((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \
	((__val) * (AVG_FACTOR))) / \
	(AVG_SAMPLES)) : \
	((__val) * (AVG_FACTOR)); \
	__new.avg = __new.avg_weight / (AVG_FACTOR); \
	__new; \
	})

	static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;

	if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)
	return ant->rssi_ant.avg;
	return DEFAULT_RSSI;
	}

	static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;

	if (ant->rssi_history)
	return ant->rssi_history;
	return DEFAULT_RSSI;
	}

	static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
	int rssi)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;
	ant->rssi_history = rssi;
	}

	static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
	{
	rt2x00dev->link.ant.rssi_ant.avg = 0;
	rt2x00dev->link.ant.rssi_ant.avg_weight = 0;
	}

	static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct antenna_setup new_ant;
	int other_antenna;

	int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
	int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);

	memcpy(&new_ant, &ant->active, sizeof(new_ant));

	/*
	* We are done sampling. Now we should evaluate the results.
	*/
	ant->flags &= ~ANTENNA_MODE_SAMPLE;

	/*
	* During the last period we have sampled the RSSI
	* from both antennas. It now is time to determine
	* which antenna demonstrated the best performance.
	* When we are already on the antenna with the best
	* performance, just create a good starting point
	* for the history and we are done.
	*/
	if (sample_current >= sample_other) {
	rt2x00link_antenna_update_rssi_history(rt2x00dev,
	sample_current);
	return;
	}

	other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

	if (ant->flags & ANTENNA_RX_DIVERSITY)
	new_ant.rx = other_antenna;

	if (ant->flags & ANTENNA_TX_DIVERSITY)
	new_ant.tx = other_antenna;

	rt2x00lib_config_antenna(rt2x00dev, new_ant);
	}

	static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct antenna_setup new_ant;
	int rssi_curr;
	int rssi_old;

	memcpy(&new_ant, &ant->active, sizeof(new_ant));

	/*
	* Get current RSSI value along with the historical value,
	* after that update the history with the current value.
	*/
	rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
	rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
	rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);

	/*
	* Legacy driver indicates that we should swap antenna's
	* when the difference in RSSI is greater that 5. This
	* also should be done when the RSSI was actually better
	* then the previous sample.
	* When the difference exceeds the threshold we should
	* sample the rssi from the other antenna to make a valid
	* comparison between the 2 antennas.
	*/
	if (abs(rssi_curr - rssi_old) < 5)
	return;

	ant->flags \|= ANTENNA_MODE_SAMPLE;

	if (ant->flags & ANTENNA_RX_DIVERSITY)
	new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

	if (ant->flags & ANTENNA_TX_DIVERSITY)
	new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;

	rt2x00lib_config_antenna(rt2x00dev, new_ant);
	}

	static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;

	/*
	* Determine if software diversity is enabled for
	* either the TX or RX antenna (or both).
	*/
	if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
	!(ant->flags & ANTENNA_TX_DIVERSITY)) {
	ant->flags = 0;
	return true;
	}

	/*
	* If we have only sampled the data over the last period
	* we should now harvest the data. Otherwise just evaluate
	* the data. The latter should only be performed once
	* every 2 seconds.
	*/
	if (ant->flags & ANTENNA_MODE_SAMPLE) {
	rt2x00lib_antenna_diversity_sample(rt2x00dev);
	return true;
	} else if (rt2x00dev->link.count & 1) {
	rt2x00lib_antenna_diversity_eval(rt2x00dev);
	return true;
	}

	return false;
	}

	void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
	struct sk_buff *skb,
	struct rxdone_entry_desc *rxdesc)
	{
	struct link *link = &rt2x00dev->link;
	struct link_qual *qual = &rt2x00dev->link.qual;
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct ieee80211_hdr hdr = (struct ieee80211_hdr )skb->data;

	/*
	* No need to update the stats for !=STA interfaces
	*/
	if (!rt2x00dev->intf_sta_count)
	return;

	/*
	* Frame was received successfully since non-succesfull
	* frames would have been dropped by the hardware.
	*/
	qual->rx_success++;

	/*
	* We are only interested in quality statistics from
	* beacons which came from the BSS which we are
	* associated with.
	*/
	if (!ieee80211_is_beacon(hdr->frame_control) \|\|
	!(rxdesc->dev_flags & RXDONE_MY_BSS))
	return;

	/*
	* Update global RSSI
	*/
	link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);

	/*
	* Update antenna RSSI
	*/
	ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);
	}

	void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
	{
	struct link *link = &rt2x00dev->link;

	/*
	* Link tuning should only be performed when
	* an active sta interface exists. AP interfaces
	* don't need link tuning and monitor mode interfaces
	* should never have to work with link tuners.
	*/
	if (!rt2x00dev->intf_sta_count)
	return;

	/**
	* While scanning, link tuning is disabled. By default
	* the most sensitive settings will be used to make sure
	* that all beacons and probe responses will be received
	* during the scan.
	*/
	if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
	return;

	rt2x00link_reset_tuner(rt2x00dev, false);

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->work, LINK_TUNE_INTERVAL);
	}

	void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
	{
	cancel_delayed_work_sync(&rt2x00dev->link.work);
	}

	void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
	{
	struct link_qual *qual = &rt2x00dev->link.qual;
	u8 vgc_level = qual->vgc_level_reg;

	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
	return;

	/*
	* Reset link information.
	* Both the currently active vgc level as well as
	* the link tuner counter should be reset. Resetting
	* the counter is important for devices where the
	* device should only perform link tuning during the
	* first minute after being enabled.
	*/
	rt2x00dev->link.count = 0;
	memset(qual, 0, sizeof(*qual));

	/*
	* Restore the VGC level as stored in the registers,
	* the driver can use this to determine if the register
	* must be updated during reset or not.
	*/
	qual->vgc_level_reg = vgc_level;

	/*
	* Reset the link tuner.
	*/
	rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);

	if (antenna)
	rt2x00link_antenna_reset(rt2x00dev);
	}

	static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
	{
	struct link_qual *qual = &rt2x00dev->link.qual;

	qual->rx_success = 0;
	qual->rx_failed = 0;
	qual->tx_success = 0;
	qual->tx_failed = 0;
	}

	static void rt2x00link_tuner(struct work_struct *work)
	{
	struct rt2x00_dev *rt2x00dev =
	container_of(work, struct rt2x00_dev, link.work.work);
	struct link *link = &rt2x00dev->link;
	struct link_qual *qual = &rt2x00dev->link.qual;

	/*
	* When the radio is shutting down we should
	* immediately cease all link tuning.
	*/
	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags) \|\|
	test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
	return;

	/*
	* Update statistics.
	*/
	rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
	rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;

	/*
	* Update quality RSSI for link tuning,
	* when we have received some frames and we managed to
	* collect the RSSI data we could use this. Otherwise we
	* must fallback to the default RSSI value.
	*/
	if (!link->avg_rssi.avg \|\| !qual->rx_success)
	qual->rssi = DEFAULT_RSSI;
	else
	qual->rssi = link->avg_rssi.avg;

	/*
	* Check if link tuning is supported by the hardware, some hardware
	* do not support link tuning at all, while other devices can disable
	* the feature from the EEPROM.
	*/
	if (test_bit(CAPABILITY_LINK_TUNING, &rt2x00dev->cap_flags))
	rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);

	/*
	* Send a signal to the led to update the led signal strength.
	*/
	rt2x00leds_led_quality(rt2x00dev, qual->rssi);

	/*
	* Evaluate antenna setup, make this the last step when
	* rt2x00lib_antenna_diversity made changes the quality
	* statistics will be reset.
	*/
	if (rt2x00lib_antenna_diversity(rt2x00dev))
	rt2x00link_reset_qual(rt2x00dev);

	/*
	* Increase tuner counter, and reschedule the next link tuner run.
	*/
	link->count++;

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->work, LINK_TUNE_INTERVAL);
	}

	void rt2x00link_start_watchdog(struct rt2x00_dev *rt2x00dev)
	{
	struct link *link = &rt2x00dev->link;

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
	rt2x00dev->ops->lib->watchdog)
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->watchdog_work,
	WATCHDOG_INTERVAL);
	}

	void rt2x00link_stop_watchdog(struct rt2x00_dev *rt2x00dev)
	{
	cancel_delayed_work_sync(&rt2x00dev->link.watchdog_work);
	}

	static void rt2x00link_watchdog(struct work_struct *work)
	{
	struct rt2x00_dev *rt2x00dev =
	container_of(work, struct rt2x00_dev, link.watchdog_work.work);
	struct link *link = &rt2x00dev->link;

	/*
	* When the radio is shutting down we should
	* immediately cease the watchdog monitoring.
	*/
	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
	return;

	rt2x00dev->ops->lib->watchdog(rt2x00dev);

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->watchdog_work,
	WATCHDOG_INTERVAL);
	}

	void rt2x00link_start_agc(struct rt2x00_dev *rt2x00dev)
	{
	struct link *link = &rt2x00dev->link;

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
	rt2x00dev->ops->lib->gain_calibration)
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->agc_work,
	AGC_INTERVAL);
	}

	void rt2x00link_start_vcocal(struct rt2x00_dev *rt2x00dev)
	{
	struct link *link = &rt2x00dev->link;

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) &&
	rt2x00dev->ops->lib->vco_calibration)
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->vco_work,
	VCO_INTERVAL);
	}

	void rt2x00link_stop_agc(struct rt2x00_dev *rt2x00dev)
	{
	cancel_delayed_work_sync(&rt2x00dev->link.agc_work);
	}

	void rt2x00link_stop_vcocal(struct rt2x00_dev *rt2x00dev)
	{
	cancel_delayed_work_sync(&rt2x00dev->link.vco_work);
	}

	static void rt2x00link_agc(struct work_struct *work)
	{
	struct rt2x00_dev *rt2x00dev =
	container_of(work, struct rt2x00_dev, link.agc_work.work);
	struct link *link = &rt2x00dev->link;

	/*
	* When the radio is shutting down we should
	* immediately cease the watchdog monitoring.
	*/
	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
	return;

	rt2x00dev->ops->lib->gain_calibration(rt2x00dev);

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->agc_work,
	AGC_INTERVAL);
	}

	static void rt2x00link_vcocal(struct work_struct *work)
	{
	struct rt2x00_dev *rt2x00dev =
	container_of(work, struct rt2x00_dev, link.vco_work.work);
	struct link *link = &rt2x00dev->link;

	/*
	* When the radio is shutting down we should
	* immediately cease the VCO calibration.
	*/
	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
	return;

	rt2x00dev->ops->lib->vco_calibration(rt2x00dev);

	if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->vco_work,
	VCO_INTERVAL);
	}

	void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
	{
	INIT_DELAYED_WORK(&rt2x00dev->link.agc_work, rt2x00link_agc);
	if (test_bit(CAPABILITY_VCO_RECALIBRATION, &rt2x00dev->cap_flags))
	INIT_DELAYED_WORK(&rt2x00dev->link.vco_work, rt2x00link_vcocal);
	INIT_DELAYED_WORK(&rt2x00dev->link.watchdog_work, rt2x00link_watchdog);
	INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
	}