/* Copyright (C) 2004 - 2009 rt2x00 SourceForge Project 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 #include #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); queue_delayed_work(rt2x00dev->hw->workqueue, &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++; queue_delayed_work(rt2x00dev->hw->workqueue, &link->work, LINK_TUNE_INTERVAL); } void rt2x00link_register(struct rt2x00_dev *rt2x00dev) { INIT_DELAYED_WORK(&rt2x00dev->link.work, rt2x00link_tuner); }