3945-rs.c

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/******************************************************************************
 *
 * Copyright(c) 2005 - 2011 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 <[email protected]>
 * 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/slab.h>
#include <net/mac80211.h>

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

#include <linux/workqueue.h>

#include "commands.h"
#include "3945.h"

#define RS_NAME "iwl-3945-rs"

static s32 il3945_expected_tpt_g[RATE_COUNT_3945] = {
    7, 13, 35, 58, 0, 0, 76, 104, 130, 168, 191, 202
};

static s32 il3945_expected_tpt_g_prot[RATE_COUNT_3945] = {
    7, 13, 35, 58, 0, 0, 0, 80, 93, 113, 123, 125
};

static s32 il3945_expected_tpt_a[RATE_COUNT_3945] = {
    0, 0, 0, 0, 40, 57, 72, 98, 121, 154, 177, 186
};

static s32 il3945_expected_tpt_b[RATE_COUNT_3945] = {
    7, 13, 35, 58, 0, 0, 0, 0, 0, 0, 0, 0
};

struct il3945_tpt_entry {
    s8 min_rssi;
    u8 idx;
};

static struct il3945_tpt_entry il3945_tpt_table_a[] = {
    {-60, RATE_54M_IDX},
    {-64, RATE_48M_IDX},
    {-72, RATE_36M_IDX},
    {-80, RATE_24M_IDX},
    {-84, RATE_18M_IDX},
    {-85, RATE_12M_IDX},
    {-87, RATE_9M_IDX},
    {-89, RATE_6M_IDX}
};

static struct il3945_tpt_entry il3945_tpt_table_g[] = {
    {-60, RATE_54M_IDX},
    {-64, RATE_48M_IDX},
    {-68, RATE_36M_IDX},
    {-80, RATE_24M_IDX},
    {-84, RATE_18M_IDX},
    {-85, RATE_12M_IDX},
    {-86, RATE_11M_IDX},
    {-88, RATE_5M_IDX},
    {-90, RATE_2M_IDX},
    {-92, RATE_1M_IDX}
};

#define RATE_MAX_WINDOW     62
#define RATE_FLUSH      (3*HZ)
#define RATE_WIN_FLUSH      (HZ/2)
#define IL39_RATE_HIGH_TH   11520
#define IL_SUCCESS_UP_TH    8960
#define IL_SUCCESS_DOWN_TH  10880
#define RATE_MIN_FAILURE_TH 6
#define RATE_MIN_SUCCESS_TH 8
#define RATE_DECREASE_TH    1920
#define RATE_RETRY_TH       15

static u8
il3945_get_rate_idx_by_rssi(s32 rssi, enum ieee80211_band band)
{
    u32 idx = 0;
    u32 table_size = 0;
    struct il3945_tpt_entry *tpt_table = NULL;

    if (rssi < IL_MIN_RSSI_VAL || rssi > IL_MAX_RSSI_VAL)
        rssi = IL_MIN_RSSI_VAL;

    switch (band) {
    case IEEE80211_BAND_2GHZ:
        tpt_table = il3945_tpt_table_g;
        table_size = ARRAY_SIZE(il3945_tpt_table_g);
        break;
    case IEEE80211_BAND_5GHZ:
        tpt_table = il3945_tpt_table_a;
        table_size = ARRAY_SIZE(il3945_tpt_table_a);
        break;
    default:
        BUG();
        break;
    }

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

    idx = min(idx, table_size - 1);

    return tpt_table[idx].idx;
}

static void
il3945_clear_win(struct il3945_rate_scale_data *win)
{
    win->data = 0;
    win->success_counter = 0;
    win->success_ratio = -1;
    win->counter = 0;
    win->average_tpt = IL_INVALID_VALUE;
    win->stamp = 0;
}

static int
il3945_rate_scale_flush_wins(struct il3945_rs_sta *rs_sta)
{
    int unflushed = 0;
    int i;
    unsigned long flags;
    struct il_priv *il __maybe_unused = rs_sta->il;

    /*
     * For each rate, if we have collected data on that rate
     * and it has been more than RATE_WIN_FLUSH
     * since we flushed, clear out the gathered stats
     */
    for (i = 0; i < 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 + RATE_WIN_FLUSH)) {
            D_RATE("flushing %d samples of rate " "idx %d\n",
                   rs_sta->win[i].counter, i);
            il3945_clear_win(&rs_sta->win[i]);
        } else
            unflushed++;
        spin_unlock_irqrestore(&rs_sta->lock, flags);
    }

    return unflushed;
}

#define RATE_FLUSH_MAX              5000    /* msec */
#define RATE_FLUSH_MIN              50  /* msec */
#define IL_AVERAGE_PACKETS             1500

static void
il3945_bg_rate_scale_flush(unsigned long data)
{
    struct il3945_rs_sta *rs_sta = (void *)data;
    struct il_priv *il __maybe_unused = rs_sta->il;
    int unflushed = 0;
    unsigned long flags;
    u32 packet_count, duration, pps;

    D_RATE("enter\n");

    unflushed = il3945_rate_scale_flush_wins(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);

        D_RATE("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 = (IL_AVERAGE_PACKETS * 1000) / pps;
            if (duration < RATE_FLUSH_MIN)
                duration = RATE_FLUSH_MIN;
            else if (duration > RATE_FLUSH_MAX)
                duration = RATE_FLUSH_MAX;
        } else
            duration = RATE_FLUSH_MAX;

        rs_sta->flush_time = msecs_to_jiffies(duration);

        D_RATE("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 = 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);

    D_RATE("leave\n");
}

static void
il3945_collect_tx_data(struct il3945_rs_sta *rs_sta,
               struct il3945_rate_scale_data *win, int success,
               int retries, int idx)
{
    unsigned long flags;
    s32 fail_count;
    struct il_priv *il __maybe_unused = rs_sta->il;

    if (!retries) {
        D_RATE("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 win; anything older isn't really relevant any more.
     * If we have filled up the sliding win, 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 (win->counter >= RATE_MAX_WINDOW) {

            /* remove earliest */
            win->counter = RATE_MAX_WINDOW - 1;

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

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

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

        retries--;
    }

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

    fail_count = win->counter - win->success_counter;

    /* Calculate average throughput, if we have enough history. */
    if (fail_count >= RATE_MIN_FAILURE_TH ||
        win->success_counter >= RATE_MIN_SUCCESS_TH)
        win->average_tpt =
            ((win->success_ratio * rs_sta->expected_tpt[idx] +
              64) / 128);
    else
        win->average_tpt = IL_INVALID_VALUE;

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

    spin_unlock_irqrestore(&rs_sta->lock, flags);
}

/*
 * Called after adding a new station to initialize rate scaling
 */
void
il3945_rs_rate_init(struct il_priv *il, struct ieee80211_sta *sta, u8 sta_id)
{
    struct ieee80211_hw *hw = il->hw;
    struct ieee80211_conf *conf = &il->hw->conf;
    struct il3945_sta_priv *psta;
    struct il3945_rs_sta *rs_sta;
    struct ieee80211_supported_band *sband;
    int i;

    D_INFO("enter\n");
    if (sta_id == il->hw_params.bcast_id)
        goto out;

    psta = (struct il3945_sta_priv *)sta->drv_priv;
    rs_sta = &psta->rs_sta;
    sband = hw->wiphy->bands[conf->channel->band];

    rs_sta->il = il;

    rs_sta->start_rate = RATE_INVALID;

    /* default to just 802.11b */
    rs_sta->expected_tpt = il3945_expected_tpt_b;

    rs_sta->last_partial_flush = jiffies;
    rs_sta->last_flush = jiffies;
    rs_sta->flush_time = RATE_FLUSH;
    rs_sta->last_tx_packets = 0;

    rs_sta->rate_scale_flush.data = (unsigned long)rs_sta;
    rs_sta->rate_scale_flush.function = il3945_bg_rate_scale_flush;

    for (i = 0; i < RATE_COUNT_3945; i++)
        il3945_clear_win(&rs_sta->win[i]);

    /* 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;
        }
    }

    il->_3945.sta_supp_rates = sta->supp_rates[sband->band];
    /* For 5 GHz band it start at IL_FIRST_OFDM_RATE */
    if (sband->band == IEEE80211_BAND_5GHZ) {
        rs_sta->last_txrate_idx += IL_FIRST_OFDM_RATE;
        il->_3945.sta_supp_rates <<= IL_FIRST_OFDM_RATE;
    }

out:
    il->stations[sta_id].used &= ~IL_STA_UCODE_INPROGRESS;

    D_INFO("leave\n");
}

static void *
il3945_rs_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
{
    return hw->priv;
}

/* rate scale requires free function to be implemented */
static void
il3945_rs_free(void *il)
{
}

static void *
il3945_rs_alloc_sta(void *il_priv, struct ieee80211_sta *sta, gfp_t gfp)
{
    struct il3945_rs_sta *rs_sta;
    struct il3945_sta_priv *psta = (void *)sta->drv_priv;
    struct il_priv *il __maybe_unused = il_priv;

    D_RATE("enter\n");

    rs_sta = &psta->rs_sta;

    spin_lock_init(&rs_sta->lock);
    init_timer(&rs_sta->rate_scale_flush);

    D_RATE("leave\n");

    return rs_sta;
}

static void
il3945_rs_free_sta(void *il_priv, struct ieee80211_sta *sta, void *il_sta)
{
    struct il3945_rs_sta *rs_sta = il_sta;

    /*
     * Be careful not to use any members of il3945_rs_sta (like trying
     * to use il_priv to print out debugging) since it may not be fully
     * initialized at this point.
     */
    del_timer_sync(&rs_sta->rate_scale_flush);
}

static void
il3945_rs_tx_status(void *il_rate, struct ieee80211_supported_band *sband,
            struct ieee80211_sta *sta, void *il_sta,
            struct sk_buff *skb)
{
    s8 retries = 0, current_count;
    int scale_rate_idx, first_idx, last_idx;
    unsigned long flags;
    struct il_priv *il = (struct il_priv *)il_rate;
    struct il3945_rs_sta *rs_sta = il_sta;
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

    D_RATE("enter\n");

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

    first_idx = sband->bitrates[info->status.rates[0].idx].hw_value;
    if (first_idx < 0 || first_idx >= RATE_COUNT_3945) {
        D_RATE("leave: Rate out of bounds: %d\n", first_idx);
        return;
    }

    if (!il_sta) {
        D_RATE("leave: No STA il data to update!\n");
        return;
    }

    /* Treat uninitialized rate scaling data same as non-existing. */
    if (!rs_sta->il) {
        D_RATE("leave: STA il data uninitialized!\n");
        return;
    }

    rs_sta->tx_packets++;

    scale_rate_idx = first_idx;
    last_idx = first_idx;

    /*
     * Update the win 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
     * il value 'retry_rate' vs. rate specific
     *
     * On exit from this while loop last_idx indicates the rate
     * at which the frame was finally transmitted (or failed if no
     * ACK)
     */
    while (retries > 1) {
        if ((retries - 1) < il->retry_rate) {
            current_count = (retries - 1);
            last_idx = scale_rate_idx;
        } else {
            current_count = il->retry_rate;
            last_idx = il3945_rs_next_rate(il, scale_rate_idx);
        }

        /* Update this rate accounting for as many retries
         * as was used for it (per current_count) */
        il3945_collect_tx_data(rs_sta, &rs_sta->win[scale_rate_idx], 0,
                       current_count, scale_rate_idx);
        D_RATE("Update rate %d for %d retries.\n", scale_rate_idx,
               current_count);

        retries -= current_count;

        scale_rate_idx = last_idx;
    }

    /* Update the last idx win with success/failure based on ACK */
    D_RATE("Update rate %d with %s.\n", last_idx,
           (info->flags & IEEE80211_TX_STAT_ACK) ? "success" : "failure");
    il3945_collect_tx_data(rs_sta, &rs_sta->win[last_idx],
                   info->flags & IEEE80211_TX_STAT_ACK, 1,
                   last_idx);

    /* We updated the rate scale win -- 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);

    D_RATE("leave\n");
}

static u16
il3945_get_adjacent_rate(struct il3945_rs_sta *rs_sta, u8 idx, u16 rate_mask,
             enum ieee80211_band band)
{
    u8 high = RATE_INVALID;
    u8 low = RATE_INVALID;
    struct il_priv *il __maybe_unused = rs_sta->il;

    /* 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 = idx - 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 = idx + 1;
        for (mask = (1 << i); i < RATE_COUNT_3945; i++, mask <<= 1) {
            if (rate_mask & mask) {
                high = i;
                break;
            }
        }

        return (high << 8) | low;
    }

    low = idx;
    while (low != RATE_INVALID) {
        if (rs_sta->tgg)
            low = il3945_rates[low].prev_rs_tgg;
        else
            low = il3945_rates[low].prev_rs;
        if (low == RATE_INVALID)
            break;
        if (rate_mask & (1 << low))
            break;
        D_RATE("Skipping masked lower rate: %d\n", low);
    }

    high = idx;
    while (high != RATE_INVALID) {
        if (rs_sta->tgg)
            high = il3945_rates[high].next_rs_tgg;
        else
            high = il3945_rates[high].next_rs;
        if (high == RATE_INVALID)
            break;
        if (rate_mask & (1 << high))
            break;
        D_RATE("Skipping masked higher rate: %d\n", high);
    }

    return (high << 8) | low;
}

static void
il3945_rs_get_rate(void *il_r, struct ieee80211_sta *sta, void *il_sta,
           struct ieee80211_tx_rate_control *txrc)
{
    struct ieee80211_supported_band *sband = txrc->sband;
    struct sk_buff *skb = txrc->skb;
    u8 low = RATE_INVALID;
    u8 high = RATE_INVALID;
    u16 high_low;
    int idx;
    struct il3945_rs_sta *rs_sta = il_sta;
    struct il3945_rate_scale_data *win = NULL;
    int current_tpt = IL_INVALID_VALUE;
    int low_tpt = IL_INVALID_VALUE;
    int high_tpt = IL_INVALID_VALUE;
    u32 fail_count;
    s8 scale_action = 0;
    unsigned long flags;
    u16 rate_mask;
    s8 max_rate_idx = -1;
    struct il_priv *il __maybe_unused = (struct il_priv *)il_r;
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

    D_RATE("enter\n");

    /* Treat uninitialized rate scaling data same as non-existing. */
    if (rs_sta && !rs_sta->il) {
        D_RATE("Rate scaling information not initialized yet.\n");
        il_sta = NULL;
    }

    if (rate_control_send_low(sta, il_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 += IL_FIRST_OFDM_RATE;
    if (max_rate_idx < 0 || max_rate_idx >= RATE_COUNT)
        max_rate_idx = -1;

    idx = min(rs_sta->last_txrate_idx & 0xffff, RATE_COUNT_3945 - 1);

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

    spin_lock_irqsave(&rs_sta->lock, flags);

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

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

    win = &(rs_sta->win[idx]);

    fail_count = win->counter - win->success_counter;

    if (fail_count < RATE_MIN_FAILURE_TH &&
        win->success_counter < RATE_MIN_SUCCESS_TH) {
        spin_unlock_irqrestore(&rs_sta->lock, flags);

        D_RATE("Invalid average_tpt on rate %d: "
               "counter: %d, success_counter: %d, "
               "expected_tpt is %sNULL\n", idx, win->counter,
               win->success_counter,
               rs_sta->expected_tpt ? "not " : "");

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

    }

    current_tpt = win->average_tpt;

    high_low =
        il3945_get_adjacent_rate(rs_sta, idx, 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 = RATE_INVALID;

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

    if (high != 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 (win->success_ratio < RATE_DECREASE_TH || !current_tpt) {
        D_RATE("decrease rate because of low success_ratio\n");
        scale_action = -1;
        /* No throughput measured yet for adjacent rates,
         * try increase */
    } else if (low_tpt == IL_INVALID_VALUE && high_tpt == IL_INVALID_VALUE) {

        if (high != RATE_INVALID &&
            win->success_ratio >= RATE_INCREASE_TH)
            scale_action = 1;
        else if (low != 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 != IL_INVALID_VALUE && high_tpt != IL_INVALID_VALUE
           && low_tpt < current_tpt && high_tpt < current_tpt) {

        D_RATE("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 != IL_INVALID_VALUE) {

            /* High rate has better throughput, Increase
             * rate */
            if (high_tpt > current_tpt &&
                win->success_ratio >= RATE_INCREASE_TH)
                scale_action = 1;
            else {
                D_RATE("decrease rate because of high tpt\n");
                scale_action = 0;
            }
        } else if (low_tpt != IL_INVALID_VALUE) {
            if (low_tpt > current_tpt) {
                D_RATE("decrease rate because of low tpt\n");
                scale_action = -1;
            } else if (win->success_ratio >= 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 != RATE_INVALID &&
        (win->success_ratio > RATE_HIGH_TH ||
         current_tpt > 100 * rs_sta->expected_tpt[low]))
        scale_action = 0;

    switch (scale_action) {
    case -1:
        /* Decrese rate */
        if (low != RATE_INVALID)
            idx = low;
        break;
    case 1:
        /* Increase rate */
        if (high != RATE_INVALID)
            idx = high;

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

    D_RATE("Selected %d (action %d) - low %d high %d\n", idx, scale_action,
           low, high);

out:

    if (sband->band == IEEE80211_BAND_5GHZ) {
        if (WARN_ON_ONCE(idx < IL_FIRST_OFDM_RATE))
            idx = IL_FIRST_OFDM_RATE;
        rs_sta->last_txrate_idx = idx;
        info->control.rates[0].idx = idx - IL_FIRST_OFDM_RATE;
    } else {
        rs_sta->last_txrate_idx = idx;
        info->control.rates[0].idx = rs_sta->last_txrate_idx;
    }

    D_RATE("leave: %d\n", idx);
}

#ifdef CONFIG_MAC80211_DEBUGFS

static ssize_t
il3945_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 il3945_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 idx=%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 < 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 = il3945_sta_dbgfs_stats_table_read,
    .open = simple_open,
    .llseek = default_llseek,
};

static void
il3945_add_debugfs(void *il, void *il_sta, struct dentry *dir)
{
    struct il3945_rs_sta *lq_sta = il_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
il3945_remove_debugfs(void *il, void *il_sta)
{
    struct il3945_rs_sta *lq_sta = il_sta;
    debugfs_remove(lq_sta->rs_sta_dbgfs_stats_table_file);
}
#endif

/*
 * Initialization of rate scaling information is done by driver after
 * the station is added. Since mac80211 calls this function before a
 * station is added we ignore it.
 */
static void
il3945_rs_rate_init_stub(void *il_r, struct ieee80211_supported_band *sband,
             struct ieee80211_sta *sta, void *il_sta)
{
}

static struct rate_control_ops rs_ops = {
    .module = NULL,
    .name = RS_NAME,
    .tx_status = il3945_rs_tx_status,
    .get_rate = il3945_rs_get_rate,
    .rate_init = il3945_rs_rate_init_stub,
    .alloc = il3945_rs_alloc,
    .free = il3945_rs_free,
    .alloc_sta = il3945_rs_alloc_sta,
    .free_sta = il3945_rs_free_sta,
#ifdef CONFIG_MAC80211_DEBUGFS
    .add_sta_debugfs = il3945_add_debugfs,
    .remove_sta_debugfs = il3945_remove_debugfs,
#endif

};

void
il3945_rate_scale_init(struct ieee80211_hw *hw, s32 sta_id)
{
    struct il_priv *il = hw->priv;
    s32 rssi = 0;
    unsigned long flags;
    struct il3945_rs_sta *rs_sta;
    struct ieee80211_sta *sta;
    struct il3945_sta_priv *psta;

    D_RATE("enter\n");

    rcu_read_lock();

    sta = ieee80211_find_sta(il->vif, il->stations[sta_id].sta.sta.addr);
    if (!sta) {
        D_RATE("Unable to find station to initialize rate scaling.\n");
        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 (il->band) {
    case IEEE80211_BAND_2GHZ:
        /* TODO: this always does G, not a regression */
        if (il->active.flags & RXON_FLG_TGG_PROTECT_MSK) {
            rs_sta->tgg = 1;
            rs_sta->expected_tpt = il3945_expected_tpt_g_prot;
        } else
            rs_sta->expected_tpt = il3945_expected_tpt_g;
        break;
    case IEEE80211_BAND_5GHZ:
        rs_sta->expected_tpt = il3945_expected_tpt_a;
        break;
    default:
        BUG();
        break;
    }

    spin_unlock_irqrestore(&rs_sta->lock, flags);

    rssi = il->_3945.last_rx_rssi;
    if (rssi == 0)
        rssi = IL_MIN_RSSI_VAL;

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

    rs_sta->start_rate = il3945_get_rate_idx_by_rssi(rssi, il->band);

    D_RATE("leave: rssi %d assign rate idx: " "%d (plcp 0x%x)\n", rssi,
           rs_sta->start_rate, il3945_rates[rs_sta->start_rate].plcp);
    rcu_read_unlock();
}

int
il3945_rate_control_register(void)
{
    return ieee80211_rate_control_register(&rs_ops);
}

void
il3945_rate_control_unregister(void)
{
    ieee80211_rate_control_unregister(&rs_ops);
}