Release 4.7 drivers/net/wireless/ralink/rt2x00/rt2x00link.c

/*
        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, see <http://www.gnu.org/licenses/>.
 */

/*
        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



static inline int rt2x00link_get_avg_rssi(struct ewma_rssi *ewma)
{
	unsigned long avg;

	avg = ewma_rssi_read(ewma);
	if (avg)
		return -avg;

	return DEFAULT_RSSI;
}

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

	if (rt2x00dev->link.qual.rx_success)
		return rt2x00link_get_avg_rssi(&ant->rssi_ant);

	return DEFAULT_RSSI;
}

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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;
}

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

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

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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);
}

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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);
}

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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;
}

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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
         */
	ewma_rssi_add(&link->avg_rssi, -rxdesc->rssi);

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

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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);
}

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

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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));
	ewma_rssi_init(&rt2x00dev->link.avg_rssi);

	/*
         * 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);
}

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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;
}

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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 (!qual->rx_success)
		qual->rssi = DEFAULT_RSSI;
	else
		qual->rssi = rt2x00link_get_avg_rssi(&link->avg_rssi);

	/*
         * 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 (rt2x00_has_cap_link_tuning(rt2x00dev))
		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);
}

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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);
}

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

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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);
}

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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);
}

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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);
}

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

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

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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);
}

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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);
}

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void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
{
	INIT_DELAYED_WORK(&rt2x00dev->link.agc_work, rt2x00link_agc);
	if (rt2x00_has_cap_vco_recalibration(rt2x00dev))
		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);
}
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1.54%
1
20.00%
Total
65
100.00%
5
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
ivo van doorn
ivo van doorn
1195
69.28%
10
41.67%
helmut schaa
helmut schaa
194
11.25%
4
16.67%
john li
john li
184
10.67%
1
4.17%
lars ericsson
lars ericsson
62
3.59%
2
8.33%
gabor juhos
gabor juhos
56
3.25%
2
8.33%
sean cross
sean cross
24
1.39%
1
4.17%
johannes berg
johannes berg
6
0.35%
1
4.17%
luis r. rodriguez
luis r. rodriguez
2
0.12%
1
4.17%
jeff kirsher
jeff kirsher
1
0.06%
1
4.17%
lucas de marchi
lucas de marchi
1
0.06%
1
4.17%
Total
1725
100.00%
24
100.00%
  
Directory: drivers/net/wireless/ralink/rt2x00

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