483 lines
14 KiB
C
483 lines
14 KiB
C
/*
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Copyright (C) 2004 - 2009 rt2x00 SourceForge Project
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<http://rt2x00.serialmonkey.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the
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Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/*
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Module: rt2x00lib
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Abstract: rt2x00 generic link tuning routines.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include "rt2x00.h"
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#include "rt2x00lib.h"
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/*
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* When we lack RSSI information return something less then -80 to
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* tell the driver to tune the device to maximum sensitivity.
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*/
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#define DEFAULT_RSSI -128
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/*
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* When no TX/RX percentage could be calculated due to lack of
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* frames on the air, we fallback to a percentage of 50%.
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* This will assure we will get at least get some decent value
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* when the link tuner starts.
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* The value will be dropped and overwritten with the correct (measured)
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* value anyway during the first run of the link tuner.
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*/
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#define DEFAULT_PERCENTAGE 50
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/*
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* Small helper macro for percentage calculation
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* This is a very simple macro with the only catch that it will
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* produce a default value in case no total value was provided.
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*/
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#define PERCENTAGE(__value, __total) \
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( (__total) ? (((__value) * 100) / (__total)) : (DEFAULT_PERCENTAGE) )
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/*
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* Helper struct and macro to work with moving/walking averages.
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* When adding a value to the average value the following calculation
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* is needed:
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*
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* avg_rssi = ((avg_rssi * 7) + rssi) / 8;
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*
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* The advantage of this approach is that we only need 1 variable
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* to store the average in (No need for a count and a total).
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* But more importantly, normal average values will over time
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* move less and less towards newly added values this results
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* that with link tuning, the device can have a very good RSSI
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* for a few minutes but when the device is moved away from the AP
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* the average will not decrease fast enough to compensate.
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* The walking average compensates this and will move towards
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* the new values correctly allowing a effective link tuning,
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* the speed of the average moving towards other values depends
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* on the value for the number of samples. The higher the number
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* of samples, the slower the average will move.
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* We use two variables to keep track of the average value to
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* compensate for the rounding errors. This can be a significant
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* error (>5dBm) if the factor is too low.
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*/
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#define AVG_SAMPLES 8
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#define AVG_FACTOR 1000
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#define MOVING_AVERAGE(__avg, __val) \
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({ \
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struct avg_val __new; \
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__new.avg_weight = \
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(__avg).avg_weight ? \
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((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \
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((__val) * (AVG_FACTOR))) / \
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(AVG_SAMPLES) ) : \
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((__val) * (AVG_FACTOR)); \
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__new.avg = __new.avg_weight / (AVG_FACTOR); \
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__new; \
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})
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/*
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* For calculating the Signal quality we have determined
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* the total number of success and failed RX and TX frames.
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* With the addition of the average RSSI value we can determine
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* the link quality using the following algorithm:
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*
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* rssi_percentage = (avg_rssi * 100) / rssi_offset
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* rx_percentage = (rx_success * 100) / rx_total
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* tx_percentage = (tx_success * 100) / tx_total
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* avg_signal = ((WEIGHT_RSSI * avg_rssi) +
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* (WEIGHT_TX * tx_percentage) +
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* (WEIGHT_RX * rx_percentage)) / 100
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*
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* This value should then be checked to not be greater then 100.
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* This means the values of WEIGHT_RSSI, WEIGHT_RX, WEIGHT_TX must
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* sum up to 100 as well.
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*/
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#define WEIGHT_RSSI 20
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#define WEIGHT_RX 40
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#define WEIGHT_TX 40
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static int rt2x00link_antenna_get_link_rssi(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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if (ant->rssi_ant.avg && rt2x00dev->link.qual.rx_success)
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return ant->rssi_ant.avg;
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return DEFAULT_RSSI;
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}
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static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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if (ant->rssi_history)
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return ant->rssi_history;
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return DEFAULT_RSSI;
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}
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static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev,
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int rssi)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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ant->rssi_history = rssi;
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}
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static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev)
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{
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rt2x00dev->link.ant.rssi_ant.avg = 0;
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rt2x00dev->link.ant.rssi_ant.avg_weight = 0;
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}
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static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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struct antenna_setup new_ant;
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int other_antenna;
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int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev);
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int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev);
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memcpy(&new_ant, &ant->active, sizeof(new_ant));
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/*
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* We are done sampling. Now we should evaluate the results.
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*/
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ant->flags &= ~ANTENNA_MODE_SAMPLE;
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/*
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* During the last period we have sampled the RSSI
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* from both antennas. It now is time to determine
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* which antenna demonstrated the best performance.
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* When we are already on the antenna with the best
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* performance, just create a good starting point
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* for the history and we are done.
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*/
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if (sample_current >= sample_other) {
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rt2x00link_antenna_update_rssi_history(rt2x00dev,
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sample_current);
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return;
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}
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other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
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if (ant->flags & ANTENNA_RX_DIVERSITY)
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new_ant.rx = other_antenna;
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if (ant->flags & ANTENNA_TX_DIVERSITY)
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new_ant.tx = other_antenna;
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rt2x00lib_config_antenna(rt2x00dev, new_ant);
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}
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static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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struct antenna_setup new_ant;
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int rssi_curr;
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int rssi_old;
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memcpy(&new_ant, &ant->active, sizeof(new_ant));
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/*
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* Get current RSSI value along with the historical value,
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* after that update the history with the current value.
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*/
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rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev);
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rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev);
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rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr);
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/*
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* Legacy driver indicates that we should swap antenna's
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* when the difference in RSSI is greater that 5. This
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* also should be done when the RSSI was actually better
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* then the previous sample.
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* When the difference exceeds the threshold we should
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* sample the rssi from the other antenna to make a valid
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* comparison between the 2 antennas.
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*/
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if (abs(rssi_curr - rssi_old) < 5)
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return;
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ant->flags |= ANTENNA_MODE_SAMPLE;
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if (ant->flags & ANTENNA_RX_DIVERSITY)
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new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
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if (ant->flags & ANTENNA_TX_DIVERSITY)
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new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A;
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rt2x00lib_config_antenna(rt2x00dev, new_ant);
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}
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static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev)
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{
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struct link_ant *ant = &rt2x00dev->link.ant;
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unsigned int flags = ant->flags;
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/*
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* Determine if software diversity is enabled for
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* either the TX or RX antenna (or both).
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* Always perform this check since within the link
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* tuner interval the configuration might have changed.
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*/
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flags &= ~ANTENNA_RX_DIVERSITY;
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flags &= ~ANTENNA_TX_DIVERSITY;
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if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY)
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flags |= ANTENNA_RX_DIVERSITY;
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if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY)
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flags |= ANTENNA_TX_DIVERSITY;
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if (!(ant->flags & ANTENNA_RX_DIVERSITY) &&
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!(ant->flags & ANTENNA_TX_DIVERSITY)) {
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ant->flags = 0;
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return true;
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}
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/* Update flags */
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ant->flags = flags;
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/*
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* If we have only sampled the data over the last period
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* we should now harvest the data. Otherwise just evaluate
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* the data. The latter should only be performed once
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* every 2 seconds.
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*/
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if (ant->flags & ANTENNA_MODE_SAMPLE) {
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rt2x00lib_antenna_diversity_sample(rt2x00dev);
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return true;
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} else if (rt2x00dev->link.count & 1) {
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rt2x00lib_antenna_diversity_eval(rt2x00dev);
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return true;
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}
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return false;
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}
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void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev,
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struct sk_buff *skb,
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struct rxdone_entry_desc *rxdesc)
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{
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struct link *link = &rt2x00dev->link;
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struct link_qual *qual = &rt2x00dev->link.qual;
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struct link_ant *ant = &rt2x00dev->link.ant;
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
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/*
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* Frame was received successfully since non-succesfull
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* frames would have been dropped by the hardware.
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*/
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qual->rx_success++;
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/*
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* We are only interested in quality statistics from
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* beacons which came from the BSS which we are
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* associated with.
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*/
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if (!ieee80211_is_beacon(hdr->frame_control) ||
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!(rxdesc->dev_flags & RXDONE_MY_BSS))
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return;
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/*
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* Update global RSSI
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*/
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link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi);
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/*
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* Update antenna RSSI
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*/
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ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi);
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}
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static void rt2x00link_precalculate_signal(struct rt2x00_dev *rt2x00dev)
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{
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struct link *link = &rt2x00dev->link;
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struct link_qual *qual = &rt2x00dev->link.qual;
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link->rx_percentage =
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PERCENTAGE(qual->rx_success, qual->rx_failed + qual->rx_success);
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link->tx_percentage =
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PERCENTAGE(qual->tx_success, qual->tx_failed + qual->tx_success);
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}
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int rt2x00link_calculate_signal(struct rt2x00_dev *rt2x00dev, int rssi)
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{
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struct link *link = &rt2x00dev->link;
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int rssi_percentage = 0;
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int signal;
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/*
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* We need a positive value for the RSSI.
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*/
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if (rssi < 0)
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rssi += rt2x00dev->rssi_offset;
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/*
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* Calculate the different percentages,
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* which will be used for the signal.
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*/
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rssi_percentage = PERCENTAGE(rssi, rt2x00dev->rssi_offset);
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/*
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* Add the individual percentages and use the WEIGHT
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* defines to calculate the current link signal.
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*/
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signal = ((WEIGHT_RSSI * rssi_percentage) +
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(WEIGHT_TX * link->tx_percentage) +
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(WEIGHT_RX * link->rx_percentage)) / 100;
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return max_t(int, signal, 100);
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}
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void rt2x00link_start_tuner(struct rt2x00_dev *rt2x00dev)
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{
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struct link *link = &rt2x00dev->link;
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/*
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* Link tuning should only be performed when
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* an active sta or master interface exists.
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* Single monitor mode interfaces should never have
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* work with link tuners.
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*/
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if (!rt2x00dev->intf_ap_count && !rt2x00dev->intf_sta_count)
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return;
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link->rx_percentage = DEFAULT_PERCENTAGE;
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link->tx_percentage = DEFAULT_PERCENTAGE;
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rt2x00link_reset_tuner(rt2x00dev, false);
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if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
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ieee80211_queue_delayed_work(rt2x00dev->hw,
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&link->work, LINK_TUNE_INTERVAL);
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}
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void rt2x00link_stop_tuner(struct rt2x00_dev *rt2x00dev)
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{
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cancel_delayed_work_sync(&rt2x00dev->link.work);
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}
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void rt2x00link_reset_tuner(struct rt2x00_dev *rt2x00dev, bool antenna)
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{
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struct link_qual *qual = &rt2x00dev->link.qual;
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if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
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return;
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/*
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* Reset link information.
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* Both the currently active vgc level as well as
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* the link tuner counter should be reset. Resetting
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* the counter is important for devices where the
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* device should only perform link tuning during the
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* first minute after being enabled.
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*/
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rt2x00dev->link.count = 0;
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memset(qual, 0, sizeof(*qual));
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/*
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* Reset the link tuner.
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*/
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rt2x00dev->ops->lib->reset_tuner(rt2x00dev, qual);
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if (antenna)
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rt2x00link_antenna_reset(rt2x00dev);
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}
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static void rt2x00link_reset_qual(struct rt2x00_dev *rt2x00dev)
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{
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struct link_qual *qual = &rt2x00dev->link.qual;
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qual->rx_success = 0;
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qual->rx_failed = 0;
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qual->tx_success = 0;
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qual->tx_failed = 0;
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}
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static void rt2x00link_tuner(struct work_struct *work)
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{
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struct rt2x00_dev *rt2x00dev =
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container_of(work, struct rt2x00_dev, link.work.work);
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struct link *link = &rt2x00dev->link;
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struct link_qual *qual = &rt2x00dev->link.qual;
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/*
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* When the radio is shutting down we should
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* immediately cease all link tuning.
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*/
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if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
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return;
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/*
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* Update statistics.
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*/
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rt2x00dev->ops->lib->link_stats(rt2x00dev, qual);
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rt2x00dev->low_level_stats.dot11FCSErrorCount += qual->rx_failed;
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/*
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* Update quality RSSI for link tuning,
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* when we have received some frames and we managed to
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* collect the RSSI data we could use this. Otherwise we
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* must fallback to the default RSSI value.
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*/
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if (!link->avg_rssi.avg || !qual->rx_success)
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qual->rssi = DEFAULT_RSSI;
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else
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qual->rssi = link->avg_rssi.avg;
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/*
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* Only perform the link tuning when Link tuning
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* has been enabled (This could have been disabled from the EEPROM).
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*/
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if (!test_bit(CONFIG_DISABLE_LINK_TUNING, &rt2x00dev->flags))
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rt2x00dev->ops->lib->link_tuner(rt2x00dev, qual, link->count);
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/*
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* Precalculate a portion of the link signal which is
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* in based on the tx/rx success/failure counters.
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*/
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rt2x00link_precalculate_signal(rt2x00dev);
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/*
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* Send a signal to the led to update the led signal strength.
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*/
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rt2x00leds_led_quality(rt2x00dev, qual->rssi);
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/*
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* Evaluate antenna setup, make this the last step when
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* rt2x00lib_antenna_diversity made changes the quality
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* statistics will be reset.
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*/
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if (rt2x00lib_antenna_diversity(rt2x00dev))
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rt2x00link_reset_qual(rt2x00dev);
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/*
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* Increase tuner counter, and reschedule the next link tuner run.
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*/
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link->count++;
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if (test_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags))
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ieee80211_queue_delayed_work(rt2x00dev->hw,
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&link->work, LINK_TUNE_INTERVAL);
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}
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void rt2x00link_register(struct rt2x00_dev *rt2x00dev)
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{
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INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner);
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}
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