drivers/net/wireless/rt2x00/rt2x00link.c - kernel/msm-4.19 - Gitiles

 /*
 	Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
 	<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

 /*
  * When no TX/RX percentage could be calculated due to lack of
  * frames on the air, we fallback to a percentage of 50%.
  * This will assure we will get at least get some decent value
  * when the link tuner starts.
  * The value will be dropped and overwritten with the correct (measured)
  * value anyway during the first run of the link tuner.
  */
 #define DEFAULT_PERCENTAGE	50

 /*
  * Small helper 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.
  */
 #define MOVING_AVERAGE(__avg, __val, __samples) \
 	( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )

 /*
  * Small helper macro for percentage calculation
  * This is a very simple macro with the only catch that it will
  * produce a default value in case no total value was provided.
  */
 #define PERCENTAGE(__value, __total) \
 	( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )

 /*
  * For calculating the Signal quality we have determined
  * the total number of success and failed RX and TX frames.
  * With the addition of the average RSSI value we can determine
  * the link quality using the following algorithm:
  *
  *         rssi_percentage = (avg_rssi * 100) / rssi_offset
  *         rx_percentage = (rx_success * 100) / rx_total
  *         tx_percentage = (tx_success * 100) / tx_total
  *         avg_signal = ((WEIGHT_RSSI * avg_rssi) +
  *                       (WEIGHT_TX * tx_percentage) +
  *                       (WEIGHT_RX * rx_percentage)) / 100
  *
  * This value should then be checked to not be greater then 100.
  * This means the values of WEIGHT_RSSI, WEIGHT_RX, WEIGHT_TX must
  * sum up to 100 as well.
  */
 #define WEIGHT_RSSI	20
 #define WEIGHT_RX	40
 #define WEIGHT_TX	40

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

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

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

 	if (ant->rssi_history[antenna - ANTENNA_A])
 		return ant->rssi_history[antenna - ANTENNA_A];
 	return DEFAULT_RSSI;
 }
 /* Small wrapper for rt2x00link_antenna_get_rssi_history() */
 #define rt2x00link_antenna_get_rssi_rx_history(__dev) \
 	rt2x00link_antenna_get_rssi_history((__dev), \
 					    (__dev)->link.ant.active.rx)
 #define rt2x00link_antenna_get_rssi_tx_history(__dev) \
 	rt2x00link_antenna_get_rssi_history((__dev), \
 					    (__dev)->link.ant.active.tx)

 static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
 						   enum antenna antenna,
 						   int rssi)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;
 	ant->rssi_history[ant->active.rx - ANTENNA_A] = rssi;
 }
 /* Small wrapper for rt2x00link_antenna_get_rssi_history() */
 #define rt2x00link_antenna_update_rssi_rx_history(__dev, __rssi) \
 	rt2x00link_antenna_update_rssi_history((__dev), \
 					       (__dev)->link.ant.active.rx, \
 					       (__rssi))
 #define rt2x00link_antenna_update_rssi_tx_history(__dev, __rssi) \
 	rt2x00link_antenna_update_rssi_history((__dev), \
 					       (__dev)->link.ant.active.tx, \
 					       (__rssi))

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

 static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
 {
 	struct link_ant *ant = &rt2x00dev->link.ant;
 	struct antenna_setup new_ant;
 	int sample_a = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_A);
 	int sample_b = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_B);

 	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, then there really is nothing for us
 	 * left to do.
 	 */
 	if (sample_a == sample_b)
 		return;

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

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

 	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_rx_history(rt2x00dev);
 	rt2x00link_antenna_update_rssi_rx_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 void 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).
 	 * Always perform this check since within the link
 	 * tuner interval the configuration might have changed.
 	 */
 	ant->flags &= ~ANTENNA_RX_DIVERSITY;
 	ant->flags &= ~ANTENNA_TX_DIVERSITY;

 	if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
 		ant->flags |= ANTENNA_RX_DIVERSITY;
 	if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
 		ant->flags |= ANTENNA_TX_DIVERSITY;

 	if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
 	    !(ant->flags & ANTENNA_TX_DIVERSITY)) {
 		ant->flags = 0;
 		return;
 	}

 	/*
 	 * 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);
 	else if (rt2x00dev->link.count & 1)
 		rt2x00lib_antenna_diversity_eval(rt2x00dev);
 }

 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;
 	int avg_rssi = rxdesc->rssi;
 	int ant_rssi = rxdesc->rssi;

 	/*
 	 * 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
 	 */
 	if (link->avg_rssi)
 		avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
 	link->avg_rssi = avg_rssi;

 	/*
 	 * Update antenna RSSI
 	 */
 	if (ant->rssi_ant)
 		ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
 	ant->rssi_ant = ant_rssi;
 }

 static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
 {
 	struct link *link = &rt2x00dev->link;
 	struct link_qual *qual = &rt2x00dev->link.qual;

 	link->rx_percentage =
 	    PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
 	link->tx_percentage =
 	    PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
 }

 int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
 {
 	struct link *link = &rt2x00dev->link;
 	int rssi_percentage = 0;
 	int signal;

 	/*
 	 * We need a positive value for the RSSI.
 	 */
 	if (rssi < 0)
 		rssi += rt2x00dev->rssi_offset;

 	/*
 	 * Calculate the different percentages,
 	 * which will be used for the signal.
 	 */
 	rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);

 	/*
 	 * Add the individual percentages and use the WEIGHT
 	 * defines to calculate the current link signal.
 	 */
 	signal = ((WEIGHT_RSSI * rssi_percentage) +
 		  (WEIGHT_TX * link->tx_percentage) +
 		  (WEIGHT_RX * link->rx_percentage)) / 100;

 	return max_t(int, signal, 100);
 }

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

 	/*
 	 * Link tuning should only be performed when
 	 * an active sta or master interface exists.
 	 * Single monitor mode interfaces should never have
 	 * work with link tuners.
 	 */
 	if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
 		return;

 	link->rx_percentage = DEFAULT_PERCENTAGE;
 	link->tx_percentage = DEFAULT_PERCENTAGE;

 	rt2x00link_reset_tuner(rt2x00dev, false);

 	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;

 	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));

 	/*
 	 * 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))
 		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 || !qual->rx_success)
 		qual->rssi = DEFAULT_RSSI;
 	else
 		qual->rssi = link->avg_rssi;

 	/*
 	 * Only perform the link tuning when Link tuning
 	 * has been enabled (This could have been disabled from the EEPROM).
 	 */
 	if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
 		rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);

 	/*
 	 * Precalculate a portion of the link signal which is
 	 * in based on the tx/rx success/failure counters.
 	 */
 	rt2x00link_precalculate_signal(rt2x00dev);

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

 	/*
 	 * Evaluate antenna setup, make this the last step since this could
 	 * possibly reset some statistics.
 	 */
 	rt2x00lib_antenna_diversity(rt2x00dev);

 	/*
 	 * Reset the quality counters which recounted during each period.
 	 */
 	rt2x00link_reset_qual(rt2x00dev);

 	/*
 	 * Increase tuner counter, and reschedule the next link tuner run.
 	 */
 	link->count++;
 	ieee80211_queue_delayed_work(rt2x00dev->hw,
 				     &link->work, LINK_TUNE_INTERVAL);
 }

 void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
 {
 	INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
 }
	/*
	Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
	<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

	/*
	* When no TX/RX percentage could be calculated due to lack of
	* frames on the air, we fallback to a percentage of 50%.
	* This will assure we will get at least get some decent value
	* when the link tuner starts.
	* The value will be dropped and overwritten with the correct (measured)
	* value anyway during the first run of the link tuner.
	*/
	#define DEFAULT_PERCENTAGE 50

	/*
	* Small helper 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.
	*/
	#define MOVING_AVERAGE(__avg, __val, __samples) \
	( (((__avg) * ((__samples) - 1)) + (__val)) / (__samples) )

	/*
	* Small helper macro for percentage calculation
	* This is a very simple macro with the only catch that it will
	* produce a default value in case no total value was provided.
	*/
	#define PERCENTAGE(__value, __total) \
	( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )

	/*
	* For calculating the Signal quality we have determined
	* the total number of success and failed RX and TX frames.
	* With the addition of the average RSSI value we can determine
	* the link quality using the following algorithm:
	*
	* rssi_percentage = (avg_rssi * 100) / rssi_offset
	* rx_percentage = (rx_success * 100) / rx_total
	* tx_percentage = (tx_success * 100) / tx_total
	* avg_signal = ((WEIGHT_RSSI * avg_rssi) +
	* (WEIGHT_TX * tx_percentage) +
	* (WEIGHT_RX * rx_percentage)) / 100
	*
	* This value should then be checked to not be greater then 100.
	* This means the values of WEIGHT_RSSI, WEIGHT_RX, WEIGHT_TX must
	* sum up to 100 as well.
	*/
	#define WEIGHT_RSSI 20
	#define WEIGHT_RX 40
	#define WEIGHT_TX 40

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

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

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

	if (ant->rssi_history[antenna - ANTENNA_A])
	return ant->rssi_history[antenna - ANTENNA_A];
	return DEFAULT_RSSI;
	}
	/* Small wrapper for rt2x00link_antenna_get_rssi_history() */
	#define rt2x00link_antenna_get_rssi_rx_history(__dev) \
	rt2x00link_antenna_get_rssi_history((__dev), \
	(__dev)->link.ant.active.rx)
	#define rt2x00link_antenna_get_rssi_tx_history(__dev) \
	rt2x00link_antenna_get_rssi_history((__dev), \
	(__dev)->link.ant.active.tx)

	static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
	enum antenna antenna,
	int rssi)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;
	ant->rssi_history[ant->active.rx - ANTENNA_A] = rssi;
	}
	/* Small wrapper for rt2x00link_antenna_get_rssi_history() */
	#define rt2x00link_antenna_update_rssi_rx_history(__dev, __rssi) \
	rt2x00link_antenna_update_rssi_history((__dev), \
	(__dev)->link.ant.active.rx, \
	(__rssi))
	#define rt2x00link_antenna_update_rssi_tx_history(__dev, __rssi) \
	rt2x00link_antenna_update_rssi_history((__dev), \
	(__dev)->link.ant.active.tx, \
	(__rssi))

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

	static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
	{
	struct link_ant *ant = &rt2x00dev->link.ant;
	struct antenna_setup new_ant;
	int sample_a = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_A);
	int sample_b = rt2x00link_antenna_get_rssi_history(rt2x00dev, ANTENNA_B);

	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, then there really is nothing for us
	* left to do.
	*/
	if (sample_a == sample_b)
	return;

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

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

	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_rx_history(rt2x00dev);
	rt2x00link_antenna_update_rssi_rx_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 void 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).
	* Always perform this check since within the link
	* tuner interval the configuration might have changed.
	*/
	ant->flags &= ~ANTENNA_RX_DIVERSITY;
	ant->flags &= ~ANTENNA_TX_DIVERSITY;

	if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
	ant->flags \|= ANTENNA_RX_DIVERSITY;
	if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
	ant->flags \|= ANTENNA_TX_DIVERSITY;

	if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
	!(ant->flags & ANTENNA_TX_DIVERSITY)) {
	ant->flags = 0;
	return;
	}

	/*
	* 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);
	else if (rt2x00dev->link.count & 1)
	rt2x00lib_antenna_diversity_eval(rt2x00dev);
	}

	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;
	int avg_rssi = rxdesc->rssi;
	int ant_rssi = rxdesc->rssi;

	/*
	* 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
	*/
	if (link->avg_rssi)
	avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi, 8);
	link->avg_rssi = avg_rssi;

	/*
	* Update antenna RSSI
	*/
	if (ant->rssi_ant)
	ant_rssi = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi, 8);
	ant->rssi_ant = ant_rssi;
	}

	static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
	{
	struct link *link = &rt2x00dev->link;
	struct link_qual *qual = &rt2x00dev->link.qual;

	link->rx_percentage =
	PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
	link->tx_percentage =
	PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
	}

	int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
	{
	struct link *link = &rt2x00dev->link;
	int rssi_percentage = 0;
	int signal;

	/*
	* We need a positive value for the RSSI.
	*/
	if (rssi < 0)
	rssi += rt2x00dev->rssi_offset;

	/*
	* Calculate the different percentages,
	* which will be used for the signal.
	*/
	rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);

	/*
	* Add the individual percentages and use the WEIGHT
	* defines to calculate the current link signal.
	*/
	signal = ((WEIGHT_RSSI * rssi_percentage) +
	(WEIGHT_TX * link->tx_percentage) +
	(WEIGHT_RX * link->rx_percentage)) / 100;

	return max_t(int, signal, 100);
	}

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

	/*
	* Link tuning should only be performed when
	* an active sta or master interface exists.
	* Single monitor mode interfaces should never have
	* work with link tuners.
	*/
	if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
	return;

	link->rx_percentage = DEFAULT_PERCENTAGE;
	link->tx_percentage = DEFAULT_PERCENTAGE;

	rt2x00link_reset_tuner(rt2x00dev, false);

	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;

	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));

	/*
	* 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))
	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 \|\| !qual->rx_success)
	qual->rssi = DEFAULT_RSSI;
	else
	qual->rssi = link->avg_rssi;

	/*
	* Only perform the link tuning when Link tuning
	* has been enabled (This could have been disabled from the EEPROM).
	*/
	if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
	rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);

	/*
	* Precalculate a portion of the link signal which is
	* in based on the tx/rx success/failure counters.
	*/
	rt2x00link_precalculate_signal(rt2x00dev);

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

	/*
	* Evaluate antenna setup, make this the last step since this could
	* possibly reset some statistics.
	*/
	rt2x00lib_antenna_diversity(rt2x00dev);

	/*
	* Reset the quality counters which recounted during each period.
	*/
	rt2x00link_reset_qual(rt2x00dev);

	/*
	* Increase tuner counter, and reschedule the next link tuner run.
	*/
	link->count++;
	ieee80211_queue_delayed_work(rt2x00dev->hw,
	&link->work, LINK_TUNE_INTERVAL);
	}

	void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
	{
	INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
	}