diff options
Diffstat (limited to 'drivers/net/wireless/rt2x00/rt2x00link.c')
| -rw-r--r-- | drivers/net/wireless/rt2x00/rt2x00link.c | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/drivers/net/wireless/rt2x00/rt2x00link.c b/drivers/net/wireless/rt2x00/rt2x00link.c new file mode 100644 index 00000000000..7eb5cd7e5f3 --- /dev/null +++ b/drivers/net/wireless/rt2x00/rt2x00link.c @@ -0,0 +1,471 @@ +/* + 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 antenna's. 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); +} + +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); +} |