/******************************************************************************
 *
 * Copyright(c) 2005 - 2009 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
 *
 * The full GNU General Public License is included in this distribution in the
 * file called LICENSE.
 *
 * Contact Information:
 *  Intel Linux Wireless <ilw@linux.intel.com>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 *****************************************************************************/

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/wireless.h>
#include <net/mac80211.h>

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/delay.h>

#include <linux/workqueue.h>

#include "iwl-commands.h"
#include "iwl-3945.h"
#include "iwl-sta.h"

#define RS_NAME "iwl-3945-rs"

struct iwl3945_rate_scale_data {
        u64 data;
        s32 success_counter;
        s32 success_ratio;
        s32 counter;
        s32 average_tpt;
        unsigned long stamp;
};

struct iwl3945_rs_sta {
        spinlock_t lock;
        struct iwl_priv *priv;
        s32 *expected_tpt;
        unsigned long last_partial_flush;
        unsigned long last_flush;
        u32 flush_time;
        u32 last_tx_packets;
        u32 tx_packets;
        u8 tgg;
        u8 flush_pending;
        u8 start_rate;
        u8 ibss_sta_added;
        struct timer_list rate_scale_flush;
        struct iwl3945_rate_scale_data win[IWL_RATE_COUNT_3945];
#ifdef CONFIG_MAC80211_DEBUGFS
        struct dentry *rs_sta_dbgfs_stats_table_file;
#endif

        /* used to be in sta_info */
        int last_txrate_idx;
};

static s32 iwl3945_expected_tpt_g[IWL_RATE_COUNT_3945] = {
        7, 13, 35, 58, 0, 0, 76, 104, 130, 168, 191, 202
};

static s32 iwl3945_expected_tpt_g_prot[IWL_RATE_COUNT_3945] = {
        7, 13, 35, 58, 0, 0, 0, 80, 93, 113, 123, 125
};

static s32 iwl3945_expected_tpt_a[IWL_RATE_COUNT_3945] = {
        0, 0, 0, 0, 40, 57, 72, 98, 121, 154, 177, 186
};

static s32 iwl3945_expected_tpt_b[IWL_RATE_COUNT_3945] = {
        7, 13, 35, 58, 0, 0, 0, 0, 0, 0, 0, 0
};

struct iwl3945_tpt_entry {
        s8 min_rssi;
        u8 index;
};

static struct iwl3945_tpt_entry iwl3945_tpt_table_a[] = {
        {-60, IWL_RATE_54M_INDEX},
        {-64, IWL_RATE_48M_INDEX},
        {-72, IWL_RATE_36M_INDEX},
        {-80, IWL_RATE_24M_INDEX},
        {-84, IWL_RATE_18M_INDEX},
        {-85, IWL_RATE_12M_INDEX},
        {-87, IWL_RATE_9M_INDEX},
        {-89, IWL_RATE_6M_INDEX}
};

static struct iwl3945_tpt_entry iwl3945_tpt_table_g[] = {
        {-60, IWL_RATE_54M_INDEX},
        {-64, IWL_RATE_48M_INDEX},
        {-68, IWL_RATE_36M_INDEX},
        {-80, IWL_RATE_24M_INDEX},
        {-84, IWL_RATE_18M_INDEX},
        {-85, IWL_RATE_12M_INDEX},
        {-86, IWL_RATE_11M_INDEX},
        {-88, IWL_RATE_5M_INDEX},
        {-90, IWL_RATE_2M_INDEX},
        {-92, IWL_RATE_1M_INDEX}
};

#define IWL_RATE_MAX_WINDOW          62
#define IWL_RATE_FLUSH           (3*HZ)
#define IWL_RATE_WIN_FLUSH       (HZ/2)
#define IWL39_RATE_HIGH_TH          11520
#define IWL_SUCCESS_UP_TH          8960
#define IWL_SUCCESS_DOWN_TH       10880
#define IWL_RATE_MIN_FAILURE_TH       6
#define IWL_RATE_MIN_SUCCESS_TH       8
#define IWL_RATE_DECREASE_TH       1920
#define IWL_RATE_RETRY_TH            15

static u8 iwl3945_get_rate_index_by_rssi(s32 rssi, enum ieee80211_band band)
{
        u32 index = 0;
        u32 table_size = 0;
        struct iwl3945_tpt_entry *tpt_table = NULL;

        if ((rssi < IWL_MIN_RSSI_VAL) || (rssi > IWL_MAX_RSSI_VAL))
                rssi = IWL_MIN_RSSI_VAL;

        switch (band) {
        case IEEE80211_BAND_2GHZ:
                tpt_table = iwl3945_tpt_table_g;
                table_size = ARRAY_SIZE(iwl3945_tpt_table_g);
                break;

        case IEEE80211_BAND_5GHZ:
                tpt_table = iwl3945_tpt_table_a;
                table_size = ARRAY_SIZE(iwl3945_tpt_table_a);
                break;

        default:
                BUG();
                break;
        }

        while ((index < table_size) && (rssi < tpt_table[index].min_rssi))
                index++;

        index = min(index, (table_size - 1));

        return tpt_table[index].index;
}

static void iwl3945_clear_window(struct iwl3945_rate_scale_data *window)
{
        window->data = 0;
        window->success_counter = 0;
        window->success_ratio = -1;
        window->counter = 0;
        window->average_tpt = IWL_INVALID_VALUE;
        window->stamp = 0;
}

/**
 * iwl3945_rate_scale_flush_windows - flush out the rate scale windows
 *
 * Returns the number of windows that have gathered data but were
 * not flushed.  If there were any that were not flushed, then
 * reschedule the rate flushing routine.
 */
static int iwl3945_rate_scale_flush_windows(struct iwl3945_rs_sta *rs_sta)
{
        int unflushed = 0;
        int i;
        unsigned long flags;
        struct iwl_priv *priv __maybe_unused = rs_sta->priv;

        /*
         * For each rate, if we have collected data on that rate
         * and it has been more than IWL_RATE_WIN_FLUSH
         * since we flushed, clear out the gathered statistics
         */
        for (i = 0; i < IWL_RATE_COUNT_3945; i++) {
                if (!rs_sta->win[i].counter)
                        continue;

                spin_lock_irqsave(&rs_sta->lock, flags);
                if (time_after(jiffies, rs_sta->win[i].stamp +
                               IWL_RATE_WIN_FLUSH)) {
                        IWL_DEBUG_RATE(priv, "flushing %d samples of rate "
                                       "index %d\n",
                                       rs_sta->win[i].counter, i);
                        iwl3945_clear_window(&rs_sta->win[i]);
                } else
                        unflushed++;
                spin_unlock_irqrestore(&rs_sta->lock, flags);
        }

        return unflushed;
}

#define IWL_RATE_FLUSH_MAX              5000    /* msec */
#define IWL_RATE_FLUSH_MIN              50      /* msec */
#define IWL_AVERAGE_PACKETS             1500

static void iwl3945_bg_rate_scale_flush(unsigned long data)
{
        struct iwl3945_rs_sta *rs_sta = (void *)data;
        struct iwl_priv *priv __maybe_unused = rs_sta->priv;
        int unflushed = 0;
        unsigned long flags;
        u32 packet_count, duration, pps;

        IWL_DEBUG_RATE(priv, "enter\n");

        unflushed = iwl3945_rate_scale_flush_windows(rs_sta);

        spin_lock_irqsave(&rs_sta->lock, flags);

        /* Number of packets Rx'd since last time this timer ran */
        packet_count = (rs_sta->tx_packets - rs_sta->last_tx_packets) + 1;

        rs_sta->last_tx_packets = rs_sta->tx_packets + 1;

        if (unflushed) {
                duration =
                    jiffies_to_msecs(jiffies - rs_sta->last_partial_flush);

                IWL_DEBUG_RATE(priv, "Tx'd %d packets in %dms\n",
                               packet_count, duration);

                /* Determine packets per second */
                if (duration)
                        pps = (packet_count * 1000) / duration;
                else
                        pps = 0;

                if (pps) {
                        duration = (IWL_AVERAGE_PACKETS * 1000) / pps;
                        if (duration < IWL_RATE_FLUSH_MIN)
                                duration = IWL_RATE_FLUSH_MIN;
                        else if (duration > IWL_RATE_FLUSH_MAX)
                                duration = IWL_RATE_FLUSH_MAX;
                } else
                        duration = IWL_RATE_FLUSH_MAX;

                rs_sta->flush_time = msecs_to_jiffies(duration);

                IWL_DEBUG_RATE(priv, "new flush period: %d msec ave %d\n",
                               duration, packet_count);

                mod_timer(&rs_sta->rate_scale_flush, jiffies +
                          rs_sta->flush_time);

                rs_sta->last_partial_flush = jiffies;
        } else {
                rs_sta->flush_time = IWL_RATE_FLUSH;
                rs_sta->flush_pending = 0;
        }
        /* If there weren't any unflushed entries, we don't schedule the timer
         * to run again */

        rs_sta->last_flush = jiffies;

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        IWL_DEBUG_RATE(priv, "leave\n");
}

/**
 * iwl3945_collect_tx_data - Update the success/failure sliding window
 *
 * We keep a sliding window of the last 64 packets transmitted
 * at this rate.  window->data contains the bitmask of successful
 * packets.
 */
static void iwl3945_collect_tx_data(struct iwl3945_rs_sta *rs_sta,
                                struct iwl3945_rate_scale_data *window,
                                int success, int retries, int index)
{
        unsigned long flags;
        s32 fail_count;
        struct iwl_priv *priv __maybe_unused = rs_sta->priv;

        if (!retries) {
                IWL_DEBUG_RATE(priv, "leave: retries == 0 -- should be at least 1\n");
                return;
        }

        spin_lock_irqsave(&rs_sta->lock, flags);

        /*
         * Keep track of only the latest 62 tx frame attempts in this rate's
         * history window; anything older isn't really relevant any more.
         * If we have filled up the sliding window, drop the oldest attempt;
         * if the oldest attempt (highest bit in bitmap) shows "success",
         * subtract "1" from the success counter (this is the main reason
         * we keep these bitmaps!).
         * */
        while (retries > 0) {
                if (window->counter >= IWL_RATE_MAX_WINDOW) {

                        /* remove earliest */
                        window->counter = IWL_RATE_MAX_WINDOW - 1;

                        if (window->data & (1ULL << (IWL_RATE_MAX_WINDOW - 1))) {
                                window->data &= ~(1ULL << (IWL_RATE_MAX_WINDOW - 1));
                                window->success_counter--;
                        }
                }

                /* Increment frames-attempted counter */
                window->counter++;

                /* Shift bitmap by one frame (throw away oldest history),
                 * OR in "1", and increment "success" if this
                 * frame was successful. */
                window->data <<= 1;
                if (success > 0) {
                        window->success_counter++;
                        window->data |= 0x1;
                        success--;
                }

                retries--;
        }

        /* Calculate current success ratio, avoid divide-by-0! */
        if (window->counter > 0)
                window->success_ratio = 128 * (100 * window->success_counter)
                                        / window->counter;
        else
                window->success_ratio = IWL_INVALID_VALUE;

        fail_count = window->counter - window->success_counter;

        /* Calculate average throughput, if we have enough history. */
        if ((fail_count >= IWL_RATE_MIN_FAILURE_TH) ||
            (window->success_counter >= IWL_RATE_MIN_SUCCESS_TH))
                window->average_tpt = ((window->success_ratio *
                                rs_sta->expected_tpt[index] + 64) / 128);
        else
                window->average_tpt = IWL_INVALID_VALUE;

        /* Tag this window as having been updated */
        window->stamp = jiffies;

        spin_unlock_irqrestore(&rs_sta->lock, flags);

}

static void rs_rate_init(void *priv_r, struct ieee80211_supported_band *sband,
                         struct ieee80211_sta *sta, void *priv_sta)
{
        struct iwl3945_rs_sta *rs_sta = priv_sta;
        struct iwl_priv *priv = (struct iwl_priv *)priv_r;
        int i;

        IWL_DEBUG_RATE(priv, "enter\n");

        /* TODO: what is a good starting rate for STA? About middle? Maybe not
         * the lowest or the highest rate.. Could consider using RSSI from
         * previous packets? Need to have IEEE 802.1X auth succeed immediately
         * after assoc.. */

        for (i = sband->n_bitrates - 1; i >= 0; i--) {
                if (sta->supp_rates[sband->band] & (1 << i)) {
                        rs_sta->last_txrate_idx = i;
                        break;
                }
        }

        priv->sta_supp_rates = sta->supp_rates[sband->band];
        /* For 5 GHz band it start at IWL_FIRST_OFDM_RATE */
        if (sband->band == IEEE80211_BAND_5GHZ) {
                rs_sta->last_txrate_idx += IWL_FIRST_OFDM_RATE;
                priv->sta_supp_rates = priv->sta_supp_rates <<
                                                IWL_FIRST_OFDM_RATE;
        }


        IWL_DEBUG_RATE(priv, "leave\n");
}

static void *rs_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
{
        return hw->priv;
}

/* rate scale requires free function to be implemented */
static void rs_free(void *priv)
{
        return;
}

static void *rs_alloc_sta(void *iwl_priv, struct ieee80211_sta *sta, gfp_t gfp)
{
        struct iwl3945_rs_sta *rs_sta;
        struct iwl3945_sta_priv *psta = (void *) sta->drv_priv;
        struct iwl_priv *priv = iwl_priv;
        int i;

        /*
         * XXX: If it's using sta->drv_priv anyway, it might
         *      as well just put all the information there.
         */

        IWL_DEBUG_RATE(priv, "enter\n");

        rs_sta = kzalloc(sizeof(struct iwl3945_rs_sta), gfp);
        if (!rs_sta) {
                IWL_DEBUG_RATE(priv, "leave: ENOMEM\n");
                return NULL;
        }

        psta->rs_sta = rs_sta;

        spin_lock_init(&rs_sta->lock);

        rs_sta->priv = priv;

        rs_sta->start_rate = IWL_RATE_INVALID;

        /* default to just 802.11b */
        rs_sta->expected_tpt = iwl3945_expected_tpt_b;

        rs_sta->last_partial_flush = jiffies;
        rs_sta->last_flush = jiffies;
        rs_sta->flush_time = IWL_RATE_FLUSH;
        rs_sta->last_tx_packets = 0;
        rs_sta->ibss_sta_added = 0;

        init_timer(&rs_sta->rate_scale_flush);
        rs_sta->rate_scale_flush.data = (unsigned long)rs_sta;
        rs_sta->rate_scale_flush.function = &iwl3945_bg_rate_scale_flush;

        for (i = 0; i < IWL_RATE_COUNT_3945; i++)
                iwl3945_clear_window(&rs_sta->win[i]);

        IWL_DEBUG_RATE(priv, "leave\n");

        return rs_sta;
}

static void rs_free_sta(void *iwl_priv, struct ieee80211_sta *sta,
                        void *priv_sta)
{
        struct iwl3945_sta_priv *psta = (void *) sta->drv_priv;
        struct iwl3945_rs_sta *rs_sta = priv_sta;
        struct iwl_priv *priv __maybe_unused = rs_sta->priv;

        psta->rs_sta = NULL;

        IWL_DEBUG_RATE(priv, "enter\n");
        del_timer_sync(&rs_sta->rate_scale_flush);
        kfree(rs_sta);
        IWL_DEBUG_RATE(priv, "leave\n");
}


/**
 * rs_tx_status - Update rate control values based on Tx results
 *
 * NOTE: Uses iwl_priv->retry_rate for the # of retries attempted by
 * the hardware for each rate.
 */
static void rs_tx_status(void *priv_rate, struct ieee80211_supported_band *sband,
                         struct ieee80211_sta *sta, void *priv_sta,
                         struct sk_buff *skb)
{
        s8 retries = 0, current_count;
        int scale_rate_index, first_index, last_index;
        unsigned long flags;
        struct iwl_priv *priv = (struct iwl_priv *)priv_rate;
        struct iwl3945_rs_sta *rs_sta = priv_sta;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

        IWL_DEBUG_RATE(priv, "enter\n");

        retries = info->status.rates[0].count;
        /* Sanity Check for retries */
        if (retries > IWL_RATE_RETRY_TH)
                retries = IWL_RATE_RETRY_TH;

        first_index = sband->bitrates[info->status.rates[0].idx].hw_value;
        if ((first_index < 0) || (first_index >= IWL_RATE_COUNT_3945)) {
                IWL_DEBUG_RATE(priv, "leave: Rate out of bounds: %d\n", first_index);
                return;
        }

        if (!priv_sta) {
                IWL_DEBUG_RATE(priv, "leave: No STA priv data to update!\n");
                return;
        }

        rs_sta->tx_packets++;

        scale_rate_index = first_index;
        last_index = first_index;

        /*
         * Update the window for each rate.  We determine which rates
         * were Tx'd based on the total number of retries vs. the number
         * of retries configured for each rate -- currently set to the
         * priv value 'retry_rate' vs. rate specific
         *
         * On exit from this while loop last_index indicates the rate
         * at which the frame was finally transmitted (or failed if no
         * ACK)
         */
        while (retries > 1) {
                if ((retries - 1) < priv->retry_rate) {
                        current_count = (retries - 1);
                        last_index = scale_rate_index;
                } else {
                        current_count = priv->retry_rate;
                        last_index = iwl3945_rs_next_rate(priv,
                                                         scale_rate_index);
                }

                /* Update this rate accounting for as many retries
                 * as was used for it (per current_count) */
                iwl3945_collect_tx_data(rs_sta,
                                    &rs_sta->win[scale_rate_index],
                                    0, current_count, scale_rate_index);
                IWL_DEBUG_RATE(priv, "Update rate %d for %d retries.\n",
                               scale_rate_index, current_count);

                retries -= current_count;

                scale_rate_index = last_index;
        }


        /* Update the last index window with success/failure based on ACK */
        IWL_DEBUG_RATE(priv, "Update rate %d with %s.\n",
                       last_index,
                       (info->flags & IEEE80211_TX_STAT_ACK) ?
                       "success" : "failure");
        iwl3945_collect_tx_data(rs_sta,
                            &rs_sta->win[last_index],
                            info->flags & IEEE80211_TX_STAT_ACK, 1, last_index);

        /* We updated the rate scale window -- if its been more than
         * flush_time since the last run, schedule the flush
         * again */
        spin_lock_irqsave(&rs_sta->lock, flags);

        if (!rs_sta->flush_pending &&
            time_after(jiffies, rs_sta->last_flush +
                       rs_sta->flush_time)) {

                rs_sta->last_partial_flush = jiffies;
                rs_sta->flush_pending = 1;
                mod_timer(&rs_sta->rate_scale_flush,
                          jiffies + rs_sta->flush_time);
        }

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        IWL_DEBUG_RATE(priv, "leave\n");

        return;
}

static u16 iwl3945_get_adjacent_rate(struct iwl3945_rs_sta *rs_sta,
                                 u8 index, u16 rate_mask, enum ieee80211_band band)
{
        u8 high = IWL_RATE_INVALID;
        u8 low = IWL_RATE_INVALID;
        struct iwl_priv *priv __maybe_unused = rs_sta->priv;

        /* 802.11A walks to the next literal adjacent rate in
         * the rate table */
        if (unlikely(band == IEEE80211_BAND_5GHZ)) {
                int i;
                u32 mask;

                /* Find the previous rate that is in the rate mask */
                i = index - 1;
                for (mask = (1 << i); i >= 0; i--, mask >>= 1) {
                        if (rate_mask & mask) {
                                low = i;
                                break;
                        }
                }

                /* Find the next rate that is in the rate mask */
                i = index + 1;
                for (mask = (1 << i); i < IWL_RATE_COUNT_3945;
                     i++, mask <<= 1) {
                        if (rate_mask & mask) {
                                high = i;
                                break;
                        }
                }

                return (high << 8) | low;
        }

        low = index;
        while (low != IWL_RATE_INVALID) {
                if (rs_sta->tgg)
                        low = iwl3945_rates[low].prev_rs_tgg;
                else
                        low = iwl3945_rates[low].prev_rs;
                if (low == IWL_RATE_INVALID)
                        break;
                if (rate_mask & (1 << low))
                        break;
                IWL_DEBUG_RATE(priv, "Skipping masked lower rate: %d\n", low);
        }

        high = index;
        while (high != IWL_RATE_INVALID) {
                if (rs_sta->tgg)
                        high = iwl3945_rates[high].next_rs_tgg;
                else
                        high = iwl3945_rates[high].next_rs;
                if (high == IWL_RATE_INVALID)
                        break;
                if (rate_mask & (1 << high))
                        break;
                IWL_DEBUG_RATE(priv, "Skipping masked higher rate: %d\n", high);
        }

        return (high << 8) | low;
}

/**
 * rs_get_rate - find the rate for the requested packet
 *
 * Returns the ieee80211_rate structure allocated by the driver.
 *
 * The rate control algorithm has no internal mapping between hw_mode's
 * rate ordering and the rate ordering used by the rate control algorithm.
 *
 * The rate control algorithm uses a single table of rates that goes across
 * the entire A/B/G spectrum vs. being limited to just one particular
 * hw_mode.
 *
 * As such, we can't convert the index obtained below into the hw_mode's
 * rate table and must reference the driver allocated rate table
 *
 */
static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta,
                        void *priv_sta, struct ieee80211_tx_rate_control *txrc)
{
        struct ieee80211_supported_band *sband = txrc->sband;
        struct sk_buff *skb = txrc->skb;
        u8 low = IWL_RATE_INVALID;
        u8 high = IWL_RATE_INVALID;
        u16 high_low;
        int index;
        struct iwl3945_rs_sta *rs_sta = priv_sta;
        struct iwl3945_rate_scale_data *window = NULL;
        int current_tpt = IWL_INVALID_VALUE;
        int low_tpt = IWL_INVALID_VALUE;
        int high_tpt = IWL_INVALID_VALUE;
        u32 fail_count;
        s8 scale_action = 0;
        unsigned long flags;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        u16 rate_mask = sta ? sta->supp_rates[sband->band] : 0;
        s8 max_rate_idx = -1;
        struct iwl_priv *priv = (struct iwl_priv *)priv_r;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

        IWL_DEBUG_RATE(priv, "enter\n");

        if (rate_control_send_low(sta, priv_sta, txrc))
                return;

        rate_mask = sta->supp_rates[sband->band];

        /* get user max rate if set */
        max_rate_idx = txrc->max_rate_idx;
        if ((sband->band == IEEE80211_BAND_5GHZ) && (max_rate_idx != -1))
                max_rate_idx += IWL_FIRST_OFDM_RATE;
        if ((max_rate_idx < 0) || (max_rate_idx >= IWL_RATE_COUNT))
                max_rate_idx = -1;

        index = min(rs_sta->last_txrate_idx & 0xffff, IWL_RATE_COUNT_3945 - 1);

        if (sband->band == IEEE80211_BAND_5GHZ)
                rate_mask = rate_mask << IWL_FIRST_OFDM_RATE;

        if ((priv->iw_mode == NL80211_IFTYPE_ADHOC) &&
            !rs_sta->ibss_sta_added) {
                u8 sta_id = iwl_find_station(priv, hdr->addr1);

                if (sta_id == IWL_INVALID_STATION) {
                        IWL_DEBUG_RATE(priv, "LQ: ADD station %pM\n",
                                       hdr->addr1);
                        sta_id = iwl_add_station(priv, hdr->addr1, false,
                                CMD_ASYNC, NULL);
                }
                if (sta_id != IWL_INVALID_STATION)
                        rs_sta->ibss_sta_added = 1;
        }

        spin_lock_irqsave(&rs_sta->lock, flags);

        /* for recent assoc, choose best rate regarding
         * to rssi value
         */
        if (rs_sta->start_rate != IWL_RATE_INVALID) {
                if (rs_sta->start_rate < index &&
                   (rate_mask & (1 << rs_sta->start_rate)))
                        index = rs_sta->start_rate;
                rs_sta->start_rate = IWL_RATE_INVALID;
        }

        /* force user max rate if set by user */
        if ((max_rate_idx != -1) && (max_rate_idx < index)) {
                if (rate_mask & (1 << max_rate_idx))
                        index = max_rate_idx;
        }

        window = &(rs_sta->win[index]);

        fail_count = window->counter - window->success_counter;

        if (((fail_count < IWL_RATE_MIN_FAILURE_TH) &&
             (window->success_counter < IWL_RATE_MIN_SUCCESS_TH))) {
                spin_unlock_irqrestore(&rs_sta->lock, flags);

                IWL_DEBUG_RATE(priv, "Invalid average_tpt on rate %d: "
                               "counter: %d, success_counter: %d, "
                               "expected_tpt is %sNULL\n",
                               index,
                               window->counter,
                               window->success_counter,
                               rs_sta->expected_tpt ? "not " : "");

           /* Can't calculate this yet; not enough history */
                window->average_tpt = IWL_INVALID_VALUE;
                goto out;

        }

        current_tpt = window->average_tpt;

        high_low = iwl3945_get_adjacent_rate(rs_sta, index, rate_mask,
                                             sband->band);
        low = high_low & 0xff;
        high = (high_low >> 8) & 0xff;

        /* If user set max rate, dont allow higher than user constrain */
        if ((max_rate_idx != -1) && (max_rate_idx < high))
                high = IWL_RATE_INVALID;

        /* Collect Measured throughputs of adjacent rates */
        if (low != IWL_RATE_INVALID)
                low_tpt = rs_sta->win[low].average_tpt;

        if (high != IWL_RATE_INVALID)
                high_tpt = rs_sta->win[high].average_tpt;

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        scale_action = 0;

        /* Low success ratio , need to drop the rate */
        if ((window->success_ratio < IWL_RATE_DECREASE_TH) || !current_tpt) {
                IWL_DEBUG_RATE(priv, "decrease rate because of low success_ratio\n");
                scale_action = -1;
        /* No throughput measured yet for adjacent rates,
         * try increase */
        } else if ((low_tpt == IWL_INVALID_VALUE) &&
                   (high_tpt == IWL_INVALID_VALUE)) {

                if (high != IWL_RATE_INVALID && window->success_ratio >= IWL_RATE_INCREASE_TH)
                        scale_action = 1;
                else if (low != IWL_RATE_INVALID)
                        scale_action = 0;

        /* Both adjacent throughputs are measured, but neither one has
         * better throughput; we're using the best rate, don't change
         * it! */
        } else if ((low_tpt != IWL_INVALID_VALUE) &&
                 (high_tpt != IWL_INVALID_VALUE) &&
                 (low_tpt < current_tpt) && (high_tpt < current_tpt)) {

                IWL_DEBUG_RATE(priv, "No action -- low [%d] & high [%d] < "
                               "current_tpt [%d]\n",
                               low_tpt, high_tpt, current_tpt);
                scale_action = 0;

        /* At least one of the rates has better throughput */
        } else {
                if (high_tpt != IWL_INVALID_VALUE) {

                        /* High rate has better throughput, Increase
                         * rate */
                        if (high_tpt > current_tpt &&
                                window->success_ratio >= IWL_RATE_INCREASE_TH)
                                scale_action = 1;
                        else {
                                IWL_DEBUG_RATE(priv,
                                    "decrease rate because of high tpt\n");
                                scale_action = 0;
                        }
                } else if (low_tpt != IWL_INVALID_VALUE) {
                        if (low_tpt > current_tpt) {
                                IWL_DEBUG_RATE(priv,
                                    "decrease rate because of low tpt\n");
                                scale_action = -1;
                        } else if (window->success_ratio >= IWL_RATE_INCREASE_TH) {
                                /* Lower rate has better
                                 * throughput,decrease rate */
                                scale_action = 1;
                        }
                }
        }

        /* Sanity check; asked for decrease, but success rate or throughput
         * has been good at old rate.  Don't change it. */
        if ((scale_action == -1) && (low != IWL_RATE_INVALID) &&
                    ((window->success_ratio > IWL_RATE_HIGH_TH) ||
                     (current_tpt > (100 * rs_sta->expected_tpt[low]))))
                scale_action = 0;

        switch (scale_action) {
        case -1:

                /* Decrese rate */
                if (low != IWL_RATE_INVALID)
                        index = low;
                break;

        case 1:
                /* Increase rate */
                if (high != IWL_RATE_INVALID)
                        index = high;

                break;

        case 0:
        default:
                /* No change */
                break;
        }

        IWL_DEBUG_RATE(priv, "Selected %d (action %d) - low %d high %d\n",
                       index, scale_action, low, high);

 out:

        rs_sta->last_txrate_idx = index;
        if (sband->band == IEEE80211_BAND_5GHZ)
                info->control.rates[0].idx = rs_sta->last_txrate_idx -
                                IWL_FIRST_OFDM_RATE;
        else
                info->control.rates[0].idx = rs_sta->last_txrate_idx;

        IWL_DEBUG_RATE(priv, "leave: %d\n", index);
}

#ifdef CONFIG_MAC80211_DEBUGFS
static int iwl3945_open_file_generic(struct inode *inode, struct file *file)
{
        file->private_data = inode->i_private;
        return 0;
}

static ssize_t iwl3945_sta_dbgfs_stats_table_read(struct file *file,
                                                  char __user *user_buf,
                                                  size_t count, loff_t *ppos)
{
        char *buff;
        int desc = 0;
        int j;
        ssize_t ret;
        struct iwl3945_rs_sta *lq_sta = file->private_data;

        buff = kmalloc(1024, GFP_KERNEL);
        if (!buff)
                return -ENOMEM;

        desc += sprintf(buff + desc, "tx packets=%d last rate index=%d\n"
                        "rate=0x%X flush time %d\n",
                        lq_sta->tx_packets,
                        lq_sta->last_txrate_idx,
                        lq_sta->start_rate, jiffies_to_msecs(lq_sta->flush_time));
        for (j = 0; j < IWL_RATE_COUNT_3945; j++) {
                desc += sprintf(buff+desc,
                                "counter=%d success=%d %%=%d\n",
                                lq_sta->win[j].counter,
                                lq_sta->win[j].success_counter,
                                lq_sta->win[j].success_ratio);
        }
        ret = simple_read_from_buffer(user_buf, count, ppos, buff, desc);
        kfree(buff);
        return ret;
}

static const struct file_operations rs_sta_dbgfs_stats_table_ops = {
        .read = iwl3945_sta_dbgfs_stats_table_read,
        .open = iwl3945_open_file_generic,
};

static void iwl3945_add_debugfs(void *priv, void *priv_sta,
                                struct dentry *dir)
{
        struct iwl3945_rs_sta *lq_sta = priv_sta;

        lq_sta->rs_sta_dbgfs_stats_table_file =
                debugfs_create_file("rate_stats_table", 0600, dir,
                lq_sta, &rs_sta_dbgfs_stats_table_ops);

}

static void iwl3945_remove_debugfs(void *priv, void *priv_sta)
{
        struct iwl3945_rs_sta *lq_sta = priv_sta;
        debugfs_remove(lq_sta->rs_sta_dbgfs_stats_table_file);
}
#endif

static struct rate_control_ops rs_ops = {
        .module = NULL,
        .name = RS_NAME,
        .tx_status = rs_tx_status,
        .get_rate = rs_get_rate,
        .rate_init = rs_rate_init,
        .alloc = rs_alloc,
        .free = rs_free,
        .alloc_sta = rs_alloc_sta,
        .free_sta = rs_free_sta,
#ifdef CONFIG_MAC80211_DEBUGFS
        .add_sta_debugfs = iwl3945_add_debugfs,
        .remove_sta_debugfs = iwl3945_remove_debugfs,
#endif

};

void iwl3945_rate_scale_init(struct ieee80211_hw *hw, s32 sta_id)
{
        struct iwl_priv *priv = hw->priv;
        s32 rssi = 0;
        unsigned long flags;
        struct iwl3945_rs_sta *rs_sta;
        struct ieee80211_sta *sta;
        struct iwl3945_sta_priv *psta;

        IWL_DEBUG_RATE(priv, "enter\n");

        rcu_read_lock();

        sta = ieee80211_find_sta(hw, priv->stations[sta_id].sta.sta.addr);
        if (!sta) {
                rcu_read_unlock();
                return;
        }

        psta = (void *) sta->drv_priv;
        rs_sta = psta->rs_sta;

        spin_lock_irqsave(&rs_sta->lock, flags);

        rs_sta->tgg = 0;
        switch (priv->band) {
        case IEEE80211_BAND_2GHZ:
                /* TODO: this always does G, not a regression */
                if (priv->active_rxon.flags & RXON_FLG_TGG_PROTECT_MSK) {
                        rs_sta->tgg = 1;
                        rs_sta->expected_tpt = iwl3945_expected_tpt_g_prot;
                } else
                        rs_sta->expected_tpt = iwl3945_expected_tpt_g;
                break;

        case IEEE80211_BAND_5GHZ:
                rs_sta->expected_tpt = iwl3945_expected_tpt_a;
                break;
        case IEEE80211_NUM_BANDS:
                BUG();
                break;
        }

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        rssi = priv->last_rx_rssi;
        if (rssi == 0)
                rssi = IWL_MIN_RSSI_VAL;

        IWL_DEBUG_RATE(priv, "Network RSSI: %d\n", rssi);

        rs_sta->start_rate = iwl3945_get_rate_index_by_rssi(rssi, priv->band);

        IWL_DEBUG_RATE(priv, "leave: rssi %d assign rate index: "
                       "%d (plcp 0x%x)\n", rssi, rs_sta->start_rate,
                       iwl3945_rates[rs_sta->start_rate].plcp);
        rcu_read_unlock();
}

int iwl3945_rate_control_register(void)
{
        return ieee80211_rate_control_register(&rs_ops);
}

void iwl3945_rate_control_unregister(void)
{
        ieee80211_rate_control_unregister(&rs_ops);
}