1 files changed, 461 insertions, 0 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00link.c b/drivers/net/wireless/rt2x00/rt2x00link.c
new file mode 100644
index 000000000000..9223a6d1f1d0
--- /dev/null
+++ b/drivers/net/wireless/rt2x00/rt2x00link.c
@@ -0,0 +1,461 @@
+/*
+        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);
+
+        qual->rx_success = 0;
+        qual->rx_failed = 0;
+        qual->tx_success = 0;
+        qual->tx_failed = 0;
+}
+
+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_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);
+
+        /*
+         * 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);
+}