| /* |
| 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 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) ) |
| |
| /* |
| * Helper struct and macro to work with moving/walking averages. |
| * When adding a value to the average value the following calculation |
| * is needed: |
| * |
| * avg_rssi = ((avg_rssi * 7) + rssi) / 8; |
| * |
| * The advantage of this approach is that we only need 1 variable |
| * to store the average in (No need for a count and a total). |
| * But more importantly, normal average values will over time |
| * move less and less towards newly added values this results |
| * that with link tuning, the device can have a very good RSSI |
| * for a few minutes but when the device is moved away from the AP |
| * the average will not decrease fast enough to compensate. |
| * The walking average compensates this and will move towards |
| * the new values correctly allowing a effective link tuning, |
| * the speed of the average moving towards other values depends |
| * on the value for the number of samples. The higher the number |
| * of samples, the slower the average will move. |
| * We use two variables to keep track of the average value to |
| * compensate for the rounding errors. This can be a significant |
| * error (>5dBm) if the factor is too low. |
| */ |
| #define AVG_SAMPLES 8 |
| #define AVG_FACTOR 1000 |
| #define MOVING_AVERAGE(__avg, __val) \ |
| ({ \ |
| struct avg_val __new; \ |
| __new.avg_weight = \ |
| (__avg).avg_weight ? \ |
| ((((__avg).avg_weight * ((AVG_SAMPLES) - 1)) + \ |
| ((__val) * (AVG_FACTOR))) / \ |
| (AVG_SAMPLES) ) : \ |
| ((__val) * (AVG_FACTOR)); \ |
| __new.avg = __new.avg_weight / (AVG_FACTOR); \ |
| __new; \ |
| }) |
| |
| /* |
| * 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.avg && rt2x00dev->link.qual.rx_success) |
| return ant->rssi_ant.avg; |
| return DEFAULT_RSSI; |
| } |
| |
| static int rt2x00link_antenna_get_rssi_history(struct rt2x00_dev *rt2x00dev) |
| { |
| struct link_ant *ant = &rt2x00dev->link.ant; |
| |
| if (ant->rssi_history) |
| return ant->rssi_history; |
| return DEFAULT_RSSI; |
| } |
| |
| static void rt2x00link_antenna_update_rssi_history(struct rt2x00_dev *rt2x00dev, |
| int rssi) |
| { |
| struct link_ant *ant = &rt2x00dev->link.ant; |
| ant->rssi_history = rssi; |
| } |
| |
| static void rt2x00link_antenna_reset(struct rt2x00_dev *rt2x00dev) |
| { |
| rt2x00dev->link.ant.rssi_ant.avg = 0; |
| rt2x00dev->link.ant.rssi_ant.avg_weight = 0; |
| } |
| |
| static void rt2x00lib_antenna_diversity_sample(struct rt2x00_dev *rt2x00dev) |
| { |
| struct link_ant *ant = &rt2x00dev->link.ant; |
| struct antenna_setup new_ant; |
| int other_antenna; |
| |
| int sample_current = rt2x00link_antenna_get_link_rssi(rt2x00dev); |
| int sample_other = rt2x00link_antenna_get_rssi_history(rt2x00dev); |
| |
| memcpy(&new_ant, &ant->active, sizeof(new_ant)); |
| |
| /* |
| * We are done sampling. Now we should evaluate the results. |
| */ |
| ant->flags &= ~ANTENNA_MODE_SAMPLE; |
| |
| /* |
| * During the last period we have sampled the RSSI |
| * from both antennas. It now is time to determine |
| * which antenna demonstrated the best performance. |
| * When we are already on the antenna with the best |
| * performance, just create a good starting point |
| * for the history and we are done. |
| */ |
| if (sample_current >= sample_other) { |
| rt2x00link_antenna_update_rssi_history(rt2x00dev, |
| sample_current); |
| return; |
| } |
| |
| other_antenna = (ant->active.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A; |
| |
| if (ant->flags & ANTENNA_RX_DIVERSITY) |
| new_ant.rx = other_antenna; |
| |
| if (ant->flags & ANTENNA_TX_DIVERSITY) |
| new_ant.tx = other_antenna; |
| |
| rt2x00lib_config_antenna(rt2x00dev, new_ant); |
| } |
| |
| static void rt2x00lib_antenna_diversity_eval(struct rt2x00_dev *rt2x00dev) |
| { |
| struct link_ant *ant = &rt2x00dev->link.ant; |
| struct antenna_setup new_ant; |
| int rssi_curr; |
| int rssi_old; |
| |
| memcpy(&new_ant, &ant->active, sizeof(new_ant)); |
| |
| /* |
| * Get current RSSI value along with the historical value, |
| * after that update the history with the current value. |
| */ |
| rssi_curr = rt2x00link_antenna_get_link_rssi(rt2x00dev); |
| rssi_old = rt2x00link_antenna_get_rssi_history(rt2x00dev); |
| rt2x00link_antenna_update_rssi_history(rt2x00dev, rssi_curr); |
| |
| /* |
| * Legacy driver indicates that we should swap antenna's |
| * when the difference in RSSI is greater that 5. This |
| * also should be done when the RSSI was actually better |
| * then the previous sample. |
| * When the difference exceeds the threshold we should |
| * sample the rssi from the other antenna to make a valid |
| * comparison between the 2 antennas. |
| */ |
| if (abs(rssi_curr - rssi_old) < 5) |
| return; |
| |
| ant->flags |= ANTENNA_MODE_SAMPLE; |
| |
| if (ant->flags & ANTENNA_RX_DIVERSITY) |
| new_ant.rx = (new_ant.rx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A; |
| |
| if (ant->flags & ANTENNA_TX_DIVERSITY) |
| new_ant.tx = (new_ant.tx == ANTENNA_A) ? ANTENNA_B : ANTENNA_A; |
| |
| rt2x00lib_config_antenna(rt2x00dev, new_ant); |
| } |
| |
| static bool rt2x00lib_antenna_diversity(struct rt2x00_dev *rt2x00dev) |
| { |
| struct link_ant *ant = &rt2x00dev->link.ant; |
| unsigned int flags = ant->flags; |
| |
| /* |
| * 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. |
| */ |
| flags &= ~ANTENNA_RX_DIVERSITY; |
| flags &= ~ANTENNA_TX_DIVERSITY; |
| |
| if (rt2x00dev->default_ant.rx == ANTENNA_SW_DIVERSITY) |
| flags |= ANTENNA_RX_DIVERSITY; |
| if (rt2x00dev->default_ant.tx == ANTENNA_SW_DIVERSITY) |
| flags |= ANTENNA_TX_DIVERSITY; |
| |
| if (!(ant->flags & ANTENNA_RX_DIVERSITY) && |
| !(ant->flags & ANTENNA_TX_DIVERSITY)) { |
| ant->flags = 0; |
| return true; |
| } |
| |
| /* Update flags */ |
| ant->flags = flags; |
| |
| /* |
| * If we have only sampled the data over the last period |
| * we should now harvest the data. Otherwise just evaluate |
| * the data. The latter should only be performed once |
| * every 2 seconds. |
| */ |
| if (ant->flags & ANTENNA_MODE_SAMPLE) { |
| rt2x00lib_antenna_diversity_sample(rt2x00dev); |
| return true; |
| } else if (rt2x00dev->link.count & 1) { |
| rt2x00lib_antenna_diversity_eval(rt2x00dev); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| void rt2x00link_update_stats(struct rt2x00_dev *rt2x00dev, |
| struct sk_buff *skb, |
| struct rxdone_entry_desc *rxdesc) |
| { |
| struct link *link = &rt2x00dev->link; |
| struct link_qual *qual = &rt2x00dev->link.qual; |
| struct link_ant *ant = &rt2x00dev->link.ant; |
| struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
| |
| /* |
| * Frame was received successfully since non-succesfull |
| * frames would have been dropped by the hardware. |
| */ |
| qual->rx_success++; |
| |
| /* |
| * We are only interested in quality statistics from |
| * beacons which came from the BSS which we are |
| * associated with. |
| */ |
| if (!ieee80211_is_beacon(hdr->frame_control) || |
| !(rxdesc->dev_flags & RXDONE_MY_BSS)) |
| return; |
| |
| /* |
| * Update global RSSI |
| */ |
| link->avg_rssi = MOVING_AVERAGE(link->avg_rssi, rxdesc->rssi); |
| |
| /* |
| * Update antenna RSSI |
| */ |
| ant->rssi_ant = MOVING_AVERAGE(ant->rssi_ant, rxdesc->rssi); |
| } |
| |
| 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.avg || !qual->rx_success) |
| qual->rssi = DEFAULT_RSSI; |
| else |
| qual->rssi = link->avg_rssi.avg; |
| |
| /* |
| * 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, 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++; |
| 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); |
| } |