[deliverable/linux.git] / drivers / net / wireless / iwlwifi / iwl-agn-rs.c

/******************************************************************************
 *
 * Copyright(c) 2005 - 2008 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:
 * James P. Ketrenos <ipw2100-admin@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 "../net/mac80211/rate.h"

#include "iwl-dev.h"
#include "iwl-sta.h"
#include "iwl-core.h"
#include "iwl-helpers.h"

#define RS_NAME "iwl-agn-rs"

#define NUM_TRY_BEFORE_ANT_TOGGLE 1
#define IWL_NUMBER_TRY      1
#define IWL_HT_NUMBER_TRY   3

#define IWL_RATE_MAX_WINDOW             62      /* # tx in history window */
#define IWL_RATE_MIN_FAILURE_TH         6       /* min failures to calc tpt */
#define IWL_RATE_MIN_SUCCESS_TH         8       /* min successes to calc tpt */

/* max time to accum history 2 seconds */
#define IWL_RATE_SCALE_FLUSH_INTVL   (2*HZ)

static u8 rs_ht_to_legacy[] = {
        IWL_RATE_6M_INDEX, IWL_RATE_6M_INDEX,
        IWL_RATE_6M_INDEX, IWL_RATE_6M_INDEX,
        IWL_RATE_6M_INDEX,
        IWL_RATE_6M_INDEX, IWL_RATE_9M_INDEX,
        IWL_RATE_12M_INDEX, IWL_RATE_18M_INDEX,
        IWL_RATE_24M_INDEX, IWL_RATE_36M_INDEX,
        IWL_RATE_48M_INDEX, IWL_RATE_54M_INDEX
};

static const u8 ant_toggle_lookup[] = {
        /*ANT_NONE -> */ ANT_NONE,
        /*ANT_A    -> */ ANT_B,
        /*ANT_B    -> */ ANT_C,
        /*ANT_AB   -> */ ANT_BC,
        /*ANT_C    -> */ ANT_A,
        /*ANT_AC   -> */ ANT_AB,
        /*ANT_BC   -> */ ANT_AC,
        /*ANT_ABC  -> */ ANT_ABC,
};

/**
 * struct iwl_rate_scale_data -- tx success history for one rate
 */
struct iwl_rate_scale_data {
        u64 data;               /* bitmap of successful frames */
        s32 success_counter;    /* number of frames successful */
        s32 success_ratio;      /* per-cent * 128  */
        s32 counter;            /* number of frames attempted */
        s32 average_tpt;        /* success ratio * expected throughput */
        unsigned long stamp;
};

/**
 * struct iwl_scale_tbl_info -- tx params and success history for all rates
 *
 * There are two of these in struct iwl_lq_sta,
 * one for "active", and one for "search".
 */
struct iwl_scale_tbl_info {
        enum iwl_table_type lq_type;
        u8 ant_type;
        u8 is_SGI;      /* 1 = short guard interval */
        u8 is_fat;      /* 1 = 40 MHz channel width */
        u8 is_dup;      /* 1 = duplicated data streams */
        u8 action;      /* change modulation; IWL_[LEGACY/SISO/MIMO]_SWITCH_* */
        s32 *expected_tpt;      /* throughput metrics; expected_tpt_G, etc. */
        u32 current_rate;  /* rate_n_flags, uCode API format */
        struct iwl_rate_scale_data win[IWL_RATE_COUNT]; /* rate histories */
};

struct iwl_traffic_load {
        unsigned long time_stamp;       /* age of the oldest statistics */
        u32 packet_count[TID_QUEUE_MAX_SIZE];   /* packet count in this time
                                                 * slice */
        u32 total;                      /* total num of packets during the
                                         * last TID_MAX_TIME_DIFF */
        u8 queue_count;                 /* number of queues that has
                                         * been used since the last cleanup */
        u8 head;                        /* start of the circular buffer */
};

/**
 * struct iwl_lq_sta -- driver's rate scaling private structure
 *
 * Pointer to this gets passed back and forth between driver and mac80211.
 */
struct iwl_lq_sta {
        u8 active_tbl;          /* index of active table, range 0-1 */
        u8 enable_counter;      /* indicates HT mode */
        u8 stay_in_tbl;         /* 1: disallow, 0: allow search for new mode */
        u8 search_better_tbl;   /* 1: currently trying alternate mode */
        s32 last_tpt;

        /* The following determine when to search for a new mode */
        u32 table_count_limit;
        u32 max_failure_limit;  /* # failed frames before new search */
        u32 max_success_limit;  /* # successful frames before new search */
        u32 table_count;
        u32 total_failed;       /* total failed frames, any/all rates */
        u32 total_success;      /* total successful frames, any/all rates */
        u32 flush_timer;        /* time staying in mode before new search */

        u8 action_counter;      /* # mode-switch actions tried */
        u8 is_green;
        u8 is_dup;
        enum ieee80211_band band;
        u8 ibss_sta_added;

        /* The following are bitmaps of rates; IWL_RATE_6M_MASK, etc. */
        u32 supp_rates;
        u16 active_legacy_rate;
        u16 active_siso_rate;
        u16 active_mimo2_rate;
        u16 active_mimo3_rate;
        u16 active_rate_basic;

        struct iwl_link_quality_cmd lq;
        struct iwl_scale_tbl_info lq_info[LQ_SIZE]; /* "active", "search" */
        struct iwl_traffic_load load[TID_MAX_LOAD_COUNT];
        u8 tx_agg_tid_en;
#ifdef CONFIG_MAC80211_DEBUGFS
        struct dentry *rs_sta_dbgfs_scale_table_file;
        struct dentry *rs_sta_dbgfs_stats_table_file;
        struct dentry *rs_sta_dbgfs_tx_agg_tid_en_file;
        u32 dbg_fixed_rate;
#endif
        struct iwl_priv *drv;
};

static void rs_rate_scale_perform(struct iwl_priv *priv,
                                   struct net_device *dev,
                                   struct ieee80211_hdr *hdr,
                                   struct sta_info *sta);
static void rs_fill_link_cmd(const struct iwl_priv *priv,
                             struct iwl_lq_sta *lq_sta, u32 rate_n_flags);


#ifdef CONFIG_MAC80211_DEBUGFS
static void rs_dbgfs_set_mcs(struct iwl_lq_sta *lq_sta,
                             u32 *rate_n_flags, int index);
#else
static void rs_dbgfs_set_mcs(struct iwl_lq_sta *lq_sta,
                             u32 *rate_n_flags, int index)
{}
#endif

/*
 * Expected throughput metrics for following rates:
 * 1, 2, 5.5, 11, 6, 9, 12, 18, 24, 36, 48, 54, 60 MBits
 * "G" is the only table that supports CCK (the first 4 rates).
 */
/*FIXME:RS:need to spearate tables for MIMO2/MIMO3*/
static s32 expected_tpt_A[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 40, 57, 72, 98, 121, 154, 177, 186, 186
};

static s32 expected_tpt_G[IWL_RATE_COUNT] = {
        7, 13, 35, 58, 40, 57, 72, 98, 121, 154, 177, 186, 186
};

static s32 expected_tpt_siso20MHz[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 42, 42, 76, 102, 124, 159, 183, 193, 202
};

static s32 expected_tpt_siso20MHzSGI[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 46, 46, 82, 110, 132, 168, 192, 202, 211
};

static s32 expected_tpt_mimo20MHz[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 74, 74, 123, 155, 179, 214, 236, 244, 251
};

static s32 expected_tpt_mimo20MHzSGI[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 81, 81, 131, 164, 188, 222, 243, 251, 257
};

static s32 expected_tpt_siso40MHz[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 77, 77, 127, 160, 184, 220, 242, 250, 257
};

static s32 expected_tpt_siso40MHzSGI[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 83, 83, 135, 169, 193, 229, 250, 257, 264
};

static s32 expected_tpt_mimo40MHz[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 123, 123, 182, 214, 235, 264, 279, 285, 289
};

static s32 expected_tpt_mimo40MHzSGI[IWL_RATE_COUNT] = {
        0, 0, 0, 0, 131, 131, 191, 222, 242, 270, 284, 289, 293
};

static inline u8 rs_extract_rate(u32 rate_n_flags)
{
        return (u8)(rate_n_flags & 0xFF);
}

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

static inline u8 rs_is_valid_ant(u8 valid_antenna, u8 ant_type)
{
        return (ant_type & valid_antenna) == ant_type;
}

/*
 *      removes the old data from the statistics. All data that is older than
 *      TID_MAX_TIME_DIFF, will be deleted.
 */
static void rs_tl_rm_old_stats(struct iwl_traffic_load *tl, u32 curr_time)
{
        /* The oldest age we want to keep */
        u32 oldest_time = curr_time - TID_MAX_TIME_DIFF;

        while (tl->queue_count &&
               (tl->time_stamp < oldest_time)) {
                tl->total -= tl->packet_count[tl->head];
                tl->packet_count[tl->head] = 0;
                tl->time_stamp += TID_QUEUE_CELL_SPACING;
                tl->queue_count--;
                tl->head++;
                if (tl->head >= TID_QUEUE_MAX_SIZE)
                        tl->head = 0;
        }
}

/*
 *      increment traffic load value for tid and also remove
 *      any old values if passed the certain time period
 */
static u8 rs_tl_add_packet(struct iwl_lq_sta *lq_data,
                           struct ieee80211_hdr *hdr)
{
        u32 curr_time = jiffies_to_msecs(jiffies);
        u32 time_diff;
        s32 index;
        struct iwl_traffic_load *tl = NULL;
        __le16 fc = hdr->frame_control;
        u8 tid;

        if (ieee80211_is_data_qos(fc)) {
                u8 *qc = ieee80211_get_qos_ctl(hdr);
                tid = qc[0] & 0xf;
        } else
                return MAX_TID_COUNT;

        tl = &lq_data->load[tid];

        curr_time -= curr_time % TID_ROUND_VALUE;

        /* Happens only for the first packet. Initialize the data */
        if (!(tl->queue_count)) {
                tl->total = 1;
                tl->time_stamp = curr_time;
                tl->queue_count = 1;
                tl->head = 0;
                tl->packet_count[0] = 1;
                return MAX_TID_COUNT;
        }

        time_diff = TIME_WRAP_AROUND(tl->time_stamp, curr_time);
        index = time_diff / TID_QUEUE_CELL_SPACING;

        /* The history is too long: remove data that is older than */
        /* TID_MAX_TIME_DIFF */
        if (index >= TID_QUEUE_MAX_SIZE)
                rs_tl_rm_old_stats(tl, curr_time);

        index = (tl->head + index) % TID_QUEUE_MAX_SIZE;
        tl->packet_count[index] = tl->packet_count[index] + 1;
        tl->total = tl->total + 1;

        if ((index + 1) > tl->queue_count)
                tl->queue_count = index + 1;

        return tid;
}

/*
        get the traffic load value for tid
*/
static u32 rs_tl_get_load(struct iwl_lq_sta *lq_data, u8 tid)
{
        u32 curr_time = jiffies_to_msecs(jiffies);
        u32 time_diff;
        s32 index;
        struct iwl_traffic_load *tl = NULL;

        if (tid >= TID_MAX_LOAD_COUNT)
                return 0;

        tl = &(lq_data->load[tid]);

        curr_time -= curr_time % TID_ROUND_VALUE;

        if (!(tl->queue_count))
                return 0;

        time_diff = TIME_WRAP_AROUND(tl->time_stamp, curr_time);
        index = time_diff / TID_QUEUE_CELL_SPACING;

        /* The history is too long: remove data that is older than */
        /* TID_MAX_TIME_DIFF */
        if (index >= TID_QUEUE_MAX_SIZE)
                rs_tl_rm_old_stats(tl, curr_time);

        return tl->total;
}

static void rs_tl_turn_on_agg_for_tid(struct iwl_priv *priv,
                                      struct iwl_lq_sta *lq_data, u8 tid,
                                      struct sta_info *sta)
{
        unsigned long state;
        DECLARE_MAC_BUF(mac);

        spin_lock_bh(&sta->lock);
        state = sta->ampdu_mlme.tid_state_tx[tid];
        spin_unlock_bh(&sta->lock);

        if (state == HT_AGG_STATE_IDLE &&
            rs_tl_get_load(lq_data, tid) > IWL_AGG_LOAD_THRESHOLD) {
                IWL_DEBUG_HT("Starting Tx agg: STA: %s tid: %d\n",
                                print_mac(mac, sta->addr), tid);
                ieee80211_start_tx_ba_session(priv->hw, sta->addr, tid);
        }
}

static void rs_tl_turn_on_agg(struct iwl_priv *priv, u8 tid,
                              struct iwl_lq_sta *lq_data,
                              struct sta_info *sta)
{
        if ((tid < TID_MAX_LOAD_COUNT))
                rs_tl_turn_on_agg_for_tid(priv, lq_data, tid, sta);
        else if (tid == IWL_AGG_ALL_TID)
                for (tid = 0; tid < TID_MAX_LOAD_COUNT; tid++)
                        rs_tl_turn_on_agg_for_tid(priv, lq_data, tid, sta);
}

static inline int get_num_of_ant_from_rate(u32 rate_n_flags)
{
        return !!(rate_n_flags & RATE_MCS_ANT_A_MSK) +
               !!(rate_n_flags & RATE_MCS_ANT_B_MSK) +
               !!(rate_n_flags & RATE_MCS_ANT_C_MSK);
}

/**
 * rs_collect_tx_data - Update the success/failure sliding window
 *
 * We keep a sliding window of the last 62 packets transmitted
 * at this rate.  window->data contains the bitmask of successful
 * packets.
 */
static int rs_collect_tx_data(struct iwl_rate_scale_data *windows,
                              int scale_index, s32 tpt, int retries,
                              int successes)
{
        struct iwl_rate_scale_data *window = NULL;
        static const u64 mask = (((u64)1) << (IWL_RATE_MAX_WINDOW - 1));
        s32 fail_count;

        if (scale_index < 0 || scale_index >= IWL_RATE_COUNT)
                return -EINVAL;

        /* Select data for current tx bit rate */
        window = &(windows[scale_index]);

        /*
         * 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 & mask) {
                                window->data &= ~mask;
                                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 (successes > 0) {
                        window->success_counter++;
                        window->data |= 0x1;
                        successes--;
                }

                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 * tpt + 64) / 128;
        else
                window->average_tpt = IWL_INVALID_VALUE;

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

        return 0;
}

/*
 * Fill uCode API rate_n_flags field, based on "search" or "active" table.
 */
/* FIXME:RS:remove this function and put the flags statically in the table */
static u32 rate_n_flags_from_tbl(struct iwl_scale_tbl_info *tbl,
                                       int index, u8 use_green)
{
        u32 rate_n_flags = 0;

        if (is_legacy(tbl->lq_type)) {
                rate_n_flags = iwl_rates[index].plcp;
                if (index >= IWL_FIRST_CCK_RATE && index <= IWL_LAST_CCK_RATE)
                        rate_n_flags |= RATE_MCS_CCK_MSK;

        } else if (is_Ht(tbl->lq_type)) {
                if (index > IWL_LAST_OFDM_RATE) {
                        IWL_ERROR("invalid HT rate index %d\n", index);
                        index = IWL_LAST_OFDM_RATE;
                }
                rate_n_flags = RATE_MCS_HT_MSK;

                if (is_siso(tbl->lq_type))
                        rate_n_flags |= iwl_rates[index].plcp_siso;
                else if (is_mimo2(tbl->lq_type))
                        rate_n_flags |= iwl_rates[index].plcp_mimo2;
                else
                        rate_n_flags |= iwl_rates[index].plcp_mimo3;
        } else {
                IWL_ERROR("Invalid tbl->lq_type %d\n", tbl->lq_type);
        }

        rate_n_flags |= ((tbl->ant_type << RATE_MCS_ANT_POS) &
                                                     RATE_MCS_ANT_ABC_MSK);

        if (is_Ht(tbl->lq_type)) {
                if (tbl->is_fat) {
                        if (tbl->is_dup)
                                rate_n_flags |= RATE_MCS_DUP_MSK;
                        else
                                rate_n_flags |= RATE_MCS_FAT_MSK;
                }
                if (tbl->is_SGI)
                        rate_n_flags |= RATE_MCS_SGI_MSK;

                if (use_green) {
                        rate_n_flags |= RATE_MCS_GF_MSK;
                        if (is_siso(tbl->lq_type) && tbl->is_SGI) {
                                rate_n_flags &= ~RATE_MCS_SGI_MSK;
                                IWL_ERROR("GF was set with SGI:SISO\n");
                        }
                }
        }
        return rate_n_flags;
}

/*
 * Interpret uCode API's rate_n_flags format,
 * fill "search" or "active" tx mode table.
 */
static int rs_get_tbl_info_from_mcs(const u32 rate_n_flags,
                                    enum ieee80211_band band,
                                    struct iwl_scale_tbl_info *tbl,
                                    int *rate_idx)
{
        u32 ant_msk = (rate_n_flags & RATE_MCS_ANT_ABC_MSK);
        u8 num_of_ant = get_num_of_ant_from_rate(rate_n_flags);
        u8 mcs;

        *rate_idx = iwl_hwrate_to_plcp_idx(rate_n_flags);

        if (*rate_idx  == IWL_RATE_INVALID) {
                *rate_idx = -1;
                return -EINVAL;
        }
        tbl->is_SGI = 0;        /* default legacy setup */
        tbl->is_fat = 0;
        tbl->is_dup = 0;
        tbl->ant_type = (ant_msk >> RATE_MCS_ANT_POS);
        tbl->lq_type = LQ_NONE;

        /* legacy rate format */
        if (!(rate_n_flags & RATE_MCS_HT_MSK)) {
                if (num_of_ant == 1) {
                        if (band == IEEE80211_BAND_5GHZ)
                                tbl->lq_type = LQ_A;
                        else
                                tbl->lq_type = LQ_G;
                }
        /* HT rate format */
        } else {
                if (rate_n_flags & RATE_MCS_SGI_MSK)
                        tbl->is_SGI = 1;

                if ((rate_n_flags & RATE_MCS_FAT_MSK) ||
                    (rate_n_flags & RATE_MCS_DUP_MSK))
                        tbl->is_fat = 1;

                if (rate_n_flags & RATE_MCS_DUP_MSK)
                        tbl->is_dup = 1;

                mcs = rs_extract_rate(rate_n_flags);

                /* SISO */
                if (mcs <= IWL_RATE_SISO_60M_PLCP) {
                        if (num_of_ant == 1)
                                tbl->lq_type = LQ_SISO; /*else NONE*/
                /* MIMO2 */
                } else if (mcs <= IWL_RATE_MIMO2_60M_PLCP) {
                        if (num_of_ant == 2)
                                tbl->lq_type = LQ_MIMO2;
                /* MIMO3 */
                } else {
                        if (num_of_ant == 3)
                                tbl->lq_type = LQ_MIMO3;
                }
        }
        return 0;
}

/* switch to another antenna/antennas and return 1 */
/* if no other valid antenna found, return 0 */
static int rs_toggle_antenna(u32 valid_ant, u32 *rate_n_flags,
                             struct iwl_scale_tbl_info *tbl)
{
        u8 new_ant_type;

        if (!tbl->ant_type || tbl->ant_type > ANT_ABC)
                return 0;

        if (!rs_is_valid_ant(valid_ant, tbl->ant_type))
                return 0;

        new_ant_type = ant_toggle_lookup[tbl->ant_type];

        while ((new_ant_type != tbl->ant_type) &&
               !rs_is_valid_ant(valid_ant, new_ant_type))
                new_ant_type = ant_toggle_lookup[new_ant_type];

        if (new_ant_type == tbl->ant_type)
                return 0;

        tbl->ant_type = new_ant_type;
        *rate_n_flags &= ~RATE_MCS_ANT_ABC_MSK;
        *rate_n_flags |= new_ant_type << RATE_MCS_ANT_POS;
        return 1;
}

/* FIXME:RS: in 4965 we don't use greenfield at all */
/* FIXME:RS: don't use greenfield for now in TX */
#if 0
static inline u8 rs_use_green(struct iwl_priv *priv, struct ieee80211_conf *conf)
{
        return (conf->flags & IEEE80211_CONF_SUPPORT_HT_MODE) &&
                priv->current_ht_config.is_green_field &&
                !priv->current_ht_config.non_GF_STA_present;
}
#endif
static inline u8 rs_use_green(struct iwl_priv *priv, struct ieee80211_conf *conf)
{
        return 0;
}

/**
 * rs_get_supported_rates - get the available rates
 *
 * if management frame or broadcast frame only return
 * basic available rates.
 *
 */
static u16 rs_get_supported_rates(struct iwl_lq_sta *lq_sta,
                                  struct ieee80211_hdr *hdr,
                                  enum iwl_table_type rate_type)
{
        if (hdr && is_multicast_ether_addr(hdr->addr1) &&
            lq_sta->active_rate_basic)
                return lq_sta->active_rate_basic;

        if (is_legacy(rate_type)) {
                return lq_sta->active_legacy_rate;
        } else {
                if (is_siso(rate_type))
                        return lq_sta->active_siso_rate;
                else if (is_mimo2(rate_type))
                        return lq_sta->active_mimo2_rate;
                else
                        return lq_sta->active_mimo3_rate;
        }
}

static u16 rs_get_adjacent_rate(struct iwl_priv *priv, u8 index, u16 rate_mask,
                                int rate_type)
{
        u8 high = IWL_RATE_INVALID;
        u8 low = IWL_RATE_INVALID;

        /* 802.11A or ht walks to the next literal adjacent rate in
         * the rate table */
        if (is_a_band(rate_type) || !is_legacy(rate_type)) {
                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; i++, mask <<= 1) {
                        if (rate_mask & mask) {
                                high = i;
                                break;
                        }
                }

                return (high << 8) | low;
        }

        low = index;
        while (low != IWL_RATE_INVALID) {
                low = iwl_rates[low].prev_rs;
                if (low == IWL_RATE_INVALID)
                        break;
                if (rate_mask & (1 << low))
                        break;
                IWL_DEBUG_RATE("Skipping masked lower rate: %d\n", low);
        }

        high = index;
        while (high != IWL_RATE_INVALID) {
                high = iwl_rates[high].next_rs;
                if (high == IWL_RATE_INVALID)
                        break;
                if (rate_mask & (1 << high))
                        break;
                IWL_DEBUG_RATE("Skipping masked higher rate: %d\n", high);
        }

        return (high << 8) | low;
}

static u32 rs_get_lower_rate(struct iwl_lq_sta *lq_sta,
                             struct iwl_scale_tbl_info *tbl,
                             u8 scale_index, u8 ht_possible)
{
        s32 low;
        u16 rate_mask;
        u16 high_low;
        u8 switch_to_legacy = 0;
        u8 is_green = lq_sta->is_green;

        /* check if we need to switch from HT to legacy rates.
         * assumption is that mandatory rates (1Mbps or 6Mbps)
         * are always supported (spec demand) */
        if (!is_legacy(tbl->lq_type) && (!ht_possible || !scale_index)) {
                switch_to_legacy = 1;
                scale_index = rs_ht_to_legacy[scale_index];
                if (lq_sta->band == IEEE80211_BAND_5GHZ)
                        tbl->lq_type = LQ_A;
                else
                        tbl->lq_type = LQ_G;

                if (num_of_ant(tbl->ant_type) > 1)
                        tbl->ant_type = ANT_A;/*FIXME:RS*/

                tbl->is_fat = 0;
                tbl->is_SGI = 0;
        }

        rate_mask = rs_get_supported_rates(lq_sta, NULL, tbl->lq_type);

        /* Mask with station rate restriction */
        if (is_legacy(tbl->lq_type)) {
                /* supp_rates has no CCK bits in A mode */
                if (lq_sta->band == IEEE80211_BAND_5GHZ)
                        rate_mask  = (u16)(rate_mask &
                           (lq_sta->supp_rates << IWL_FIRST_OFDM_RATE));
                else
                        rate_mask = (u16)(rate_mask & lq_sta->supp_rates);
        }

        /* If we switched from HT to legacy, check current rate */
        if (switch_to_legacy && (rate_mask & (1 << scale_index))) {
                low = scale_index;
                goto out;
        }

        high_low = rs_get_adjacent_rate(lq_sta->drv, scale_index, rate_mask,
                                        tbl->lq_type);
        low = high_low & 0xff;

        if (low == IWL_RATE_INVALID)
                low = scale_index;

out:
        return rate_n_flags_from_tbl(tbl, low, is_green);
}

/*
 * mac80211 sends us Tx status
 */
static void rs_tx_status(void *priv_rate, struct net_device *dev,
                         struct sk_buff *skb)
{
        int status;
        u8 retries;
        int rs_index, index = 0;
        struct iwl_lq_sta *lq_sta;
        struct iwl_link_quality_cmd *table;
        struct sta_info *sta;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        struct iwl_priv *priv = (struct iwl_priv *)priv_rate;
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct ieee80211_hw *hw = local_to_hw(local);
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct iwl_rate_scale_data *window = NULL;
        struct iwl_rate_scale_data *search_win = NULL;
        u32 tx_rate;
        struct iwl_scale_tbl_info tbl_type;
        struct iwl_scale_tbl_info *curr_tbl, *search_tbl;
        u8 active_index = 0;
        __le16 fc = hdr->frame_control;
        s32 tpt = 0;

        IWL_DEBUG_RATE_LIMIT("get frame ack response, update rate scale window\n");

        if (!ieee80211_is_data(fc) || is_multicast_ether_addr(hdr->addr1))
                return;

        /* This packet was aggregated but doesn't carry rate scale info */
        if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
            !(info->flags & IEEE80211_TX_STAT_AMPDU))
                return;

        retries = info->status.retry_count;

        if (retries > 15)
                retries = 15;

        rcu_read_lock();

        sta = sta_info_get(local, hdr->addr1);

        if (!sta || !sta->rate_ctrl_priv)
                goto out;


        lq_sta = (struct iwl_lq_sta *)sta->rate_ctrl_priv;

        if ((priv->iw_mode == IEEE80211_IF_TYPE_IBSS) &&
            !lq_sta->ibss_sta_added)
                goto out;

        table = &lq_sta->lq;
        active_index = lq_sta->active_tbl;

        curr_tbl = &(lq_sta->lq_info[active_index]);
        search_tbl = &(lq_sta->lq_info[(1 - active_index)]);
        window = (struct iwl_rate_scale_data *)&(curr_tbl->win[0]);
        search_win = (struct iwl_rate_scale_data *)&(search_tbl->win[0]);

        /*
         * Ignore this Tx frame response if its initial rate doesn't match
         * that of latest Link Quality command.  There may be stragglers
         * from a previous Link Quality command, but we're no longer interested
         * in those; they're either from the "active" mode while we're trying
         * to check "search" mode, or a prior "search" mode after we've moved
         * to a new "search" mode (which might become the new "active" mode).
         */
        tx_rate = le32_to_cpu(table->rs_table[0].rate_n_flags);
        rs_get_tbl_info_from_mcs(tx_rate, priv->band, &tbl_type, &rs_index);
        if (priv->band == IEEE80211_BAND_5GHZ)
                rs_index -= IWL_FIRST_OFDM_RATE;

        if ((info->tx_rate_idx < 0) ||
            (tbl_type.is_SGI ^
                !!(info->flags & IEEE80211_TX_CTL_SHORT_GI)) ||
            (tbl_type.is_fat ^
                !!(info->flags & IEEE80211_TX_CTL_40_MHZ_WIDTH)) ||
            (tbl_type.is_dup ^
                !!(info->flags & IEEE80211_TX_CTL_DUP_DATA)) ||
            (tbl_type.ant_type ^ info->antenna_sel_tx) ||
            (!!(tx_rate & RATE_MCS_HT_MSK) ^
                !!(info->flags & IEEE80211_TX_CTL_OFDM_HT)) ||
            (!!(tx_rate & RATE_MCS_GF_MSK) ^
                !!(info->flags & IEEE80211_TX_CTL_GREEN_FIELD)) ||
            (hw->wiphy->bands[priv->band]->bitrates[rs_index].bitrate !=
             hw->wiphy->bands[info->band]->bitrates[info->tx_rate_idx].bitrate)) {
                IWL_DEBUG_RATE("initial rate does not match 0x%x\n", tx_rate);
                goto out;
        }

        /* Update frame history window with "failure" for each Tx retry. */
        while (retries) {
                /* Look up the rate and other info used for each tx attempt.
                 * Each tx attempt steps one entry deeper in the rate table. */
                tx_rate = le32_to_cpu(table->rs_table[index].rate_n_flags);
                rs_get_tbl_info_from_mcs(tx_rate, priv->band,
                                          &tbl_type, &rs_index);

                /* If type matches "search" table,
                 * add failure to "search" history */
                if ((tbl_type.lq_type == search_tbl->lq_type) &&
                    (tbl_type.ant_type == search_tbl->ant_type) &&
                    (tbl_type.is_SGI == search_tbl->is_SGI)) {
                        if (search_tbl->expected_tpt)
                                tpt = search_tbl->expected_tpt[rs_index];
                        else
                                tpt = 0;
                        rs_collect_tx_data(search_win, rs_index, tpt, 1, 0);

                /* Else if type matches "current/active" table,
                 * add failure to "current/active" history */
                } else if ((tbl_type.lq_type == curr_tbl->lq_type) &&
                           (tbl_type.ant_type == curr_tbl->ant_type) &&
                           (tbl_type.is_SGI == curr_tbl->is_SGI)) {
                        if (curr_tbl->expected_tpt)
                                tpt = curr_tbl->expected_tpt[rs_index];
                        else
                                tpt = 0;
                        rs_collect_tx_data(window, rs_index, tpt, 1, 0);
                }

                /* If not searching for a new mode, increment failed counter
                 * ... this helps determine when to start searching again */
                if (lq_sta->stay_in_tbl)
                        lq_sta->total_failed++;
                --retries;
                index++;

        }

        /*
         * Find (by rate) the history window to update with final Tx attempt;
         * if Tx was successful first try, use original rate,
         * else look up the rate that was, finally, successful.
         */
        tx_rate = le32_to_cpu(table->rs_table[index].rate_n_flags);
        rs_get_tbl_info_from_mcs(tx_rate, priv->band, &tbl_type, &rs_index);

        /* Update frame history window with "success" if Tx got ACKed ... */
        status = !!(info->flags & IEEE80211_TX_STAT_ACK);

        /* If type matches "search" table,
         * add final tx status to "search" history */
        if ((tbl_type.lq_type == search_tbl->lq_type) &&
            (tbl_type.ant_type == search_tbl->ant_type) &&
            (tbl_type.is_SGI == search_tbl->is_SGI)) {
                if (search_tbl->expected_tpt)
                        tpt = search_tbl->expected_tpt[rs_index];
                else
                        tpt = 0;
                if (info->flags & IEEE80211_TX_CTL_AMPDU)
                        rs_collect_tx_data(search_win, rs_index, tpt,
                                           info->status.ampdu_ack_len,
                                           info->status.ampdu_ack_map);
                else
                        rs_collect_tx_data(search_win, rs_index, tpt,
                                           1, status);
        /* Else if type matches "current/active" table,
         * add final tx status to "current/active" history */
        } else if ((tbl_type.lq_type == curr_tbl->lq_type) &&
                   (tbl_type.ant_type == curr_tbl->ant_type) &&
                   (tbl_type.is_SGI == curr_tbl->is_SGI)) {
                if (curr_tbl->expected_tpt)
                        tpt = curr_tbl->expected_tpt[rs_index];
                else
                        tpt = 0;
                if (info->flags & IEEE80211_TX_CTL_AMPDU)
                        rs_collect_tx_data(window, rs_index, tpt,
                                           info->status.ampdu_ack_len,
                                           info->status.ampdu_ack_map);
                else
                        rs_collect_tx_data(window, rs_index, tpt,
                                           1, status);
        }

        /* If not searching for new mode, increment success/failed counter
         * ... these help determine when to start searching again */
        if (lq_sta->stay_in_tbl) {
                if (info->flags & IEEE80211_TX_CTL_AMPDU) {
                        lq_sta->total_success += info->status.ampdu_ack_map;
                        lq_sta->total_failed +=
                             (info->status.ampdu_ack_len - info->status.ampdu_ack_map);
                } else {
                        if (status)
                                lq_sta->total_success++;
                        else
                                lq_sta->total_failed++;
                }
        }

        /* See if there's a better rate or modulation mode to try. */
        rs_rate_scale_perform(priv, dev, hdr, sta);
out:
        rcu_read_unlock();
        return;
}

/*
 * Begin a period of staying with a selected modulation mode.
 * Set "stay_in_tbl" flag to prevent any mode switches.
 * Set frame tx success limits according to legacy vs. high-throughput,
 * and reset overall (spanning all rates) tx success history statistics.
 * These control how long we stay using same modulation mode before
 * searching for a new mode.
 */
static void rs_set_stay_in_table(struct iwl_priv *priv, u8 is_legacy,
                                 struct iwl_lq_sta *lq_sta)
{
        IWL_DEBUG_RATE("we are staying in the same table\n");
        lq_sta->stay_in_tbl = 1;        /* only place this gets set */
        if (is_legacy) {
                lq_sta->table_count_limit = IWL_LEGACY_TABLE_COUNT;
                lq_sta->max_failure_limit = IWL_LEGACY_FAILURE_LIMIT;
                lq_sta->max_success_limit = IWL_LEGACY_SUCCESS_LIMIT;
        } else {
                lq_sta->table_count_limit = IWL_NONE_LEGACY_TABLE_COUNT;
                lq_sta->max_failure_limit = IWL_NONE_LEGACY_FAILURE_LIMIT;
                lq_sta->max_success_limit = IWL_NONE_LEGACY_SUCCESS_LIMIT;
        }
        lq_sta->table_count = 0;
        lq_sta->total_failed = 0;
        lq_sta->total_success = 0;
}

/*
 * Find correct throughput table for given mode of modulation
 */
static void rs_set_expected_tpt_table(struct iwl_lq_sta *lq_sta,
                                      struct iwl_scale_tbl_info *tbl)
{
        if (is_legacy(tbl->lq_type)) {
                if (!is_a_band(tbl->lq_type))
                        tbl->expected_tpt = expected_tpt_G;
                else
                        tbl->expected_tpt = expected_tpt_A;
        } else if (is_siso(tbl->lq_type)) {
                if (tbl->is_fat && !lq_sta->is_dup)
                        if (tbl->is_SGI)
                                tbl->expected_tpt = expected_tpt_siso40MHzSGI;
                        else
                                tbl->expected_tpt = expected_tpt_siso40MHz;
                else if (tbl->is_SGI)
                        tbl->expected_tpt = expected_tpt_siso20MHzSGI;
                else
                        tbl->expected_tpt = expected_tpt_siso20MHz;

        } else if (is_mimo(tbl->lq_type)) { /* FIXME:need to separate mimo2/3 */
                if (tbl->is_fat && !lq_sta->is_dup)
                        if (tbl->is_SGI)
                                tbl->expected_tpt = expected_tpt_mimo40MHzSGI;
                        else
                                tbl->expected_tpt = expected_tpt_mimo40MHz;
                else if (tbl->is_SGI)
                        tbl->expected_tpt = expected_tpt_mimo20MHzSGI;
                else
                        tbl->expected_tpt = expected_tpt_mimo20MHz;
        } else
                tbl->expected_tpt = expected_tpt_G;
}

/*
 * Find starting rate for new "search" high-throughput mode of modulation.
 * Goal is to find lowest expected rate (under perfect conditions) that is
 * above the current measured throughput of "active" mode, to give new mode
 * a fair chance to prove itself without too many challenges.
 *
 * This gets called when transitioning to more aggressive modulation
 * (i.e. legacy to SISO or MIMO, or SISO to MIMO), as well as less aggressive
 * (i.e. MIMO to SISO).  When moving to MIMO, bit rate will typically need
 * to decrease to match "active" throughput.  When moving from MIMO to SISO,
 * bit rate will typically need to increase, but not if performance was bad.
 */
static s32 rs_get_best_rate(struct iwl_priv *priv,
                            struct iwl_lq_sta *lq_sta,
                            struct iwl_scale_tbl_info *tbl,     /* "search" */
                            u16 rate_mask, s8 index)
{
        /* "active" values */
        struct iwl_scale_tbl_info *active_tbl =
            &(lq_sta->lq_info[lq_sta->active_tbl]);
        s32 active_sr = active_tbl->win[index].success_ratio;
        s32 active_tpt = active_tbl->expected_tpt[index];

        /* expected "search" throughput */
        s32 *tpt_tbl = tbl->expected_tpt;

        s32 new_rate, high, low, start_hi;
        u16 high_low;
        s8 rate = index;

        new_rate = high = low = start_hi = IWL_RATE_INVALID;

        for (; ;) {
                high_low = rs_get_adjacent_rate(priv, rate, rate_mask,
                                                tbl->lq_type);

                low = high_low & 0xff;
                high = (high_low >> 8) & 0xff;

                /*
                 * Lower the "search" bit rate, to give new "search" mode
                 * approximately the same throughput as "active" if:
                 *
                 * 1) "Active" mode has been working modestly well (but not
                 *    great), and expected "search" throughput (under perfect
                 *    conditions) at candidate rate is above the actual
                 *    measured "active" throughput (but less than expected
                 *    "active" throughput under perfect conditions).
                 * OR
                 * 2) "Active" mode has been working perfectly or very well
                 *    and expected "search" throughput (under perfect
                 *    conditions) at candidate rate is above expected
                 *    "active" throughput (under perfect conditions).
                 */
                if ((((100 * tpt_tbl[rate]) > lq_sta->last_tpt) &&
                     ((active_sr > IWL_RATE_DECREASE_TH) &&
                      (active_sr <= IWL_RATE_HIGH_TH) &&
                      (tpt_tbl[rate] <= active_tpt))) ||
                    ((active_sr >= IWL_RATE_SCALE_SWITCH) &&
                     (tpt_tbl[rate] > active_tpt))) {

                        /* (2nd or later pass)
                         * If we've already tried to raise the rate, and are
                         * now trying to lower it, use the higher rate. */
                        if (start_hi != IWL_RATE_INVALID) {
                                new_rate = start_hi;
                                break;
                        }

                        new_rate = rate;

                        /* Loop again with lower rate */
                        if (low != IWL_RATE_INVALID)
                                rate = low;

                        /* Lower rate not available, use the original */
                        else
                                break;

                /* Else try to raise the "search" rate to match "active" */
                } else {
                        /* (2nd or later pass)
                         * If we've already tried to lower the rate, and are
                         * now trying to raise it, use the lower rate. */
                        if (new_rate != IWL_RATE_INVALID)
                                break;

                        /* Loop again with higher rate */
                        else if (high != IWL_RATE_INVALID) {
                                start_hi = high;
                                rate = high;

                        /* Higher rate not available, use the original */
                        } else {
                                new_rate = rate;
                                break;
                        }
                }
        }

        return new_rate;
}

/*
 * Set up search table for MIMO
 */
static int rs_switch_to_mimo2(struct iwl_priv *priv,
                             struct iwl_lq_sta *lq_sta,
                             struct ieee80211_conf *conf,
                             struct sta_info *sta,
                             struct iwl_scale_tbl_info *tbl, int index)
{
        u16 rate_mask;
        s32 rate;
        s8 is_green = lq_sta->is_green;

        if (!(conf->flags & IEEE80211_CONF_SUPPORT_HT_MODE) ||
            !sta->ht_info.ht_supported)
                return -1;

        if (((sta->ht_info.cap & IEEE80211_HT_CAP_SM_PS) >> 2)
                                                == WLAN_HT_CAP_SM_PS_STATIC)
                return -1;

        /* Need both Tx chains/antennas to support MIMO */
        if (priv->hw_params.tx_chains_num < 2)
                return -1;

        IWL_DEBUG_RATE("LQ: try to switch to MIMO2\n");

        tbl->lq_type = LQ_MIMO2;
        tbl->is_dup = lq_sta->is_dup;
        tbl->action = 0;
        rate_mask = lq_sta->active_mimo2_rate;

        if (priv->current_ht_config.supported_chan_width
                                        == IWL_CHANNEL_WIDTH_40MHZ)
                tbl->is_fat = 1;
        else
                tbl->is_fat = 0;

        /* FIXME: - don't toggle SGI here
        if (tbl->is_fat) {
                if (priv->current_ht_config.sgf & HT_SHORT_GI_40MHZ_ONLY)
                        tbl->is_SGI = 1;
                else
                        tbl->is_SGI = 0;
        } else if (priv->current_ht_config.sgf & HT_SHORT_GI_20MHZ_ONLY)
                tbl->is_SGI = 1;
        else
                tbl->is_SGI = 0;
        */

        rs_set_expected_tpt_table(lq_sta, tbl);

        rate = rs_get_best_rate(priv, lq_sta, tbl, rate_mask, index);

        IWL_DEBUG_RATE("LQ: MIMO2 best rate %d mask %X\n", rate, rate_mask);

        if ((rate == IWL_RATE_INVALID) || !((1 << rate) & rate_mask)) {
                IWL_DEBUG_RATE("Can't switch with index %d rate mask %x\n",
                                                rate, rate_mask);
                return -1;
        }
        tbl->current_rate = rate_n_flags_from_tbl(tbl, rate, is_green);

        IWL_DEBUG_RATE("LQ: Switch to new mcs %X index is green %X\n",
                     tbl->current_rate, is_green);
        return 0;
}

/*
 * Set up search table for SISO
 */
static int rs_switch_to_siso(struct iwl_priv *priv,
                             struct iwl_lq_sta *lq_sta,
                             struct ieee80211_conf *conf,
                             struct sta_info *sta,
                             struct iwl_scale_tbl_info *tbl, int index)
{
        u16 rate_mask;
        u8 is_green = lq_sta->is_green;
        s32 rate;

        if (!(conf->flags & IEEE80211_CONF_SUPPORT_HT_MODE) ||
            !sta->ht_info.ht_supported)
                return -1;

        IWL_DEBUG_RATE("LQ: try to switch to SISO\n");

        tbl->is_dup = lq_sta->is_dup;
        tbl->lq_type = LQ_SISO;
        tbl->action = 0;
        rate_mask = lq_sta->active_siso_rate;

        if (priv->current_ht_config.supported_chan_width
            == IWL_CHANNEL_WIDTH_40MHZ)
                tbl->is_fat = 1;
        else
                tbl->is_fat = 0;

        /* FIXME: - don't toggle SGI here
        if (tbl->is_fat) {
                if (priv->current_ht_config.sgf & HT_SHORT_GI_40MHZ_ONLY)
                        tbl->is_SGI = 1;
                else
                        tbl->is_SGI = 0;
        } else if (priv->current_ht_config.sgf & HT_SHORT_GI_20MHZ_ONLY)
                tbl->is_SGI = 1;
        else
                tbl->is_SGI = 0;
        */

        if (is_green)
                tbl->is_SGI = 0; /*11n spec: no SGI in SISO+Greenfield*/

        rs_set_expected_tpt_table(lq_sta, tbl);
        rate = rs_get_best_rate(priv, lq_sta, tbl, rate_mask, index);

        IWL_DEBUG_RATE("LQ: get best rate %d mask %X\n", rate, rate_mask);
        if ((rate == IWL_RATE_INVALID) || !((1 << rate) & rate_mask)) {
                IWL_DEBUG_RATE("can not switch with index %d rate mask %x\n",
                             rate, rate_mask);
                return -1;
        }
        tbl->current_rate = rate_n_flags_from_tbl(tbl, rate, is_green);
        IWL_DEBUG_RATE("LQ: Switch to new mcs %X index is green %X\n",
                     tbl->current_rate, is_green);
        return 0;
}

/*
 * Try to switch to new modulation mode from legacy
 */
static int rs_move_legacy_other(struct iwl_priv *priv,
                                struct iwl_lq_sta *lq_sta,
                                struct ieee80211_conf *conf,
                                struct sta_info *sta,
                                int index)
{
        struct iwl_scale_tbl_info *tbl = &(lq_sta->lq_info[lq_sta->active_tbl]);
        struct iwl_scale_tbl_info *search_tbl =
                                &(lq_sta->lq_info[(1 - lq_sta->active_tbl)]);
        struct iwl_rate_scale_data *window = &(tbl->win[index]);
        u32 sz = (sizeof(struct iwl_scale_tbl_info) -
                  (sizeof(struct iwl_rate_scale_data) * IWL_RATE_COUNT));
        u8 start_action = tbl->action;
        u8 valid_tx_ant = priv->hw_params.valid_tx_ant;
        int ret = 0;

        for (; ;) {
                switch (tbl->action) {
                case IWL_LEGACY_SWITCH_ANTENNA:
                        IWL_DEBUG_RATE("LQ: Legacy toggle Antenna\n");

                        lq_sta->action_counter++;

                        /* Don't change antenna if success has been great */
                        if (window->success_ratio >= IWL_RS_GOOD_RATIO)
                                break;

                        /* Set up search table to try other antenna */
                        memcpy(search_tbl, tbl, sz);

                        if (rs_toggle_antenna(valid_tx_ant,
                                &search_tbl->current_rate, search_tbl)) {
                                lq_sta->search_better_tbl = 1;
                                goto out;
                        }
                        break;
                case IWL_LEGACY_SWITCH_SISO:
                        IWL_DEBUG_RATE("LQ: Legacy switch to SISO\n");

                        /* Set up search table to try SISO */
                        memcpy(search_tbl, tbl, sz);
                        search_tbl->is_SGI = 0;
                        ret = rs_switch_to_siso(priv, lq_sta, conf, sta,
                                                 search_tbl, index);
                        if (!ret) {
                                lq_sta->search_better_tbl = 1;
                                lq_sta->action_counter = 0;
                                goto out;
                        }

                        break;
                case IWL_LEGACY_SWITCH_MIMO2:
                        IWL_DEBUG_RATE("LQ: Legacy switch to MIMO2\n");

                        /* Set up search table to try MIMO */
                        memcpy(search_tbl, tbl, sz);
                        search_tbl->is_SGI = 0;
                        search_tbl->ant_type = ANT_AB;/*FIXME:RS*/
                                /*FIXME:RS:need to check ant validity*/
                        ret = rs_switch_to_mimo2(priv, lq_sta, conf, sta,
                                                 search_tbl, index);
                        if (!ret) {
                                lq_sta->search_better_tbl = 1;
                                lq_sta->action_counter = 0;
                                goto out;
                        }
                        break;
                }
                tbl->action++;
                if (tbl->action > IWL_LEGACY_SWITCH_MIMO2)
                        tbl->action = IWL_LEGACY_SWITCH_ANTENNA;

                if (tbl->action == start_action)
                        break;

        }
        return 0;

 out:
        tbl->action++;
        if (tbl->action > IWL_LEGACY_SWITCH_MIMO2)
                tbl->action = IWL_LEGACY_SWITCH_ANTENNA;
        return 0;

}

/*
 * Try to switch to new modulation mode from SISO
 */
static int rs_move_siso_to_other(struct iwl_priv *priv,
                                 struct iwl_lq_sta *lq_sta,
                                 struct ieee80211_conf *conf,
                                 struct sta_info *sta, int index)
{
        u8 is_green = lq_sta->is_green;
        struct iwl_scale_tbl_info *tbl = &(lq_sta->lq_info[lq_sta->active_tbl]);
        struct iwl_scale_tbl_info *search_tbl =
                                &(lq_sta->lq_info[(1 - lq_sta->active_tbl)]);
        struct iwl_rate_scale_data *window = &(tbl->win[index]);
        u32 sz = (sizeof(struct iwl_scale_tbl_info) -
                  (sizeof(struct iwl_rate_scale_data) * IWL_RATE_COUNT));
        u8 start_action = tbl->action;
        u8 valid_tx_ant = priv->hw_params.valid_tx_ant;
        int ret;

        for (;;) {
                lq_sta->action_counter++;
                switch (tbl->action) {
                case IWL_SISO_SWITCH_ANTENNA:
                        IWL_DEBUG_RATE("LQ: SISO toggle Antenna\n");
                        if (window->success_ratio >= IWL_RS_GOOD_RATIO)
                                break;

                        memcpy(search_tbl, tbl, sz);
                        if (rs_toggle_antenna(valid_tx_ant,
                                       &search_tbl->current_rate, search_tbl)) {
                                lq_sta->search_better_tbl = 1;
                                goto out;
                        }
                        break;
                case IWL_SISO_SWITCH_MIMO2:
                        IWL_DEBUG_RATE("LQ: SISO switch to MIMO2\n");
                        memcpy(search_tbl, tbl, sz);
                        search_tbl->is_SGI = 0;
                        search_tbl->ant_type = ANT_AB; /*FIXME:RS*/
                        ret = rs_switch_to_mimo2(priv, lq_sta, conf, sta,
                                                 search_tbl, index);
                        if (!ret) {
                                lq_sta->search_better_tbl = 1;
                                goto out;
                        }
                        break;
                case IWL_SISO_SWITCH_GI:
                        if (!tbl->is_fat &&
                                !(priv->current_ht_config.sgf &
                                                HT_SHORT_GI_20MHZ))
                                break;
                        if (tbl->is_fat &&
                                !(priv->current_ht_config.sgf &
                                                HT_SHORT_GI_40MHZ))
                                break;

                        IWL_DEBUG_RATE("LQ: SISO toggle SGI/NGI\n");

                        memcpy(search_tbl, tbl, sz);
                        if (is_green) {
                                if (!tbl->is_SGI)
                                        break;
                                else
                                        IWL_ERROR("SGI was set in GF+SISO\n");
                        }
                        search_tbl->is_SGI = !tbl->is_SGI;
                        rs_set_expected_tpt_table(lq_sta, search_tbl);
                        if (tbl->is_SGI) {
                                s32 tpt = lq_sta->last_tpt / 100;
                                if (tpt >= search_tbl->expected_tpt[index])
                                        break;
                        }
                        search_tbl->current_rate = rate_n_flags_from_tbl(
                                                search_tbl, index, is_green);
                        lq_sta->search_better_tbl = 1;
                        goto out;
                }
                tbl->action++;
                if (tbl->action > IWL_SISO_SWITCH_GI)
                        tbl->action = IWL_SISO_SWITCH_ANTENNA;

                if (tbl->action == start_action)
                        break;
        }
        return 0;

 out:
        tbl->action++;
        if (tbl->action > IWL_SISO_SWITCH_GI)
                tbl->action = IWL_SISO_SWITCH_ANTENNA;
        return 0;
}

/*
 * Try to switch to new modulation mode from MIMO
 */
static int rs_move_mimo_to_other(struct iwl_priv *priv,
                                 struct iwl_lq_sta *lq_sta,
                                 struct ieee80211_conf *conf,
                                 struct sta_info *sta, int index)
{
        s8 is_green = lq_sta->is_green;
        struct iwl_scale_tbl_info *tbl = &(lq_sta->lq_info[lq_sta->active_tbl]);
        struct iwl_scale_tbl_info *search_tbl =
                                &(lq_sta->lq_info[(1 - lq_sta->active_tbl)]);
        u32 sz = (sizeof(struct iwl_scale_tbl_info) -
                  (sizeof(struct iwl_rate_scale_data) * IWL_RATE_COUNT));
        u8 start_action = tbl->action;
        /*u8 valid_tx_ant = priv->hw_params.valid_tx_ant;*/
        int ret;

        for (;;) {
                lq_sta->action_counter++;
                switch (tbl->action) {
                case IWL_MIMO_SWITCH_ANTENNA_A:
                case IWL_MIMO_SWITCH_ANTENNA_B:
                        IWL_DEBUG_RATE("LQ: MIMO2 switch to SISO\n");

                        /* Set up new search table for SISO */
                        memcpy(search_tbl, tbl, sz);

                        /*FIXME:RS:need to check ant validity + C*/
                        if (tbl->action == IWL_MIMO_SWITCH_ANTENNA_A)
                                search_tbl->ant_type = ANT_A;
                        else
                                search_tbl->ant_type = ANT_B;

                        ret = rs_switch_to_siso(priv, lq_sta, conf, sta,
                                                 search_tbl, index);
                        if (!ret) {
                                lq_sta->search_better_tbl = 1;
                                goto out;
                        }
                        break;

                case IWL_MIMO_SWITCH_GI:
                        if (!tbl->is_fat &&
                                !(priv->current_ht_config.sgf &
                                                HT_SHORT_GI_20MHZ))
                                break;
                        if (tbl->is_fat &&
                                !(priv->current_ht_config.sgf &
                                                HT_SHORT_GI_40MHZ))
                                break;

                        IWL_DEBUG_RATE("LQ: MIMO toggle SGI/NGI\n");

                        /* Set up new search table for MIMO */
                        memcpy(search_tbl, tbl, sz);
                        search_tbl->is_SGI = !tbl->is_SGI;
                        rs_set_expected_tpt_table(lq_sta, search_tbl);
                        /*
                         * If active table already uses the fastest possible
                         * modulation (dual stream with short guard interval),
                         * and it's working well, there's no need to look
                         * for a better type of modulation!
                         */
                        if (tbl->is_SGI) {
                                s32 tpt = lq_sta->last_tpt / 100;
                                if (tpt >= search_tbl->expected_tpt[index])
                                        break;
                        }
                        search_tbl->current_rate = rate_n_flags_from_tbl(
                                                search_tbl, index, is_green);
                        lq_sta->search_better_tbl = 1;
                        goto out;

                }
                tbl->action++;
                if (tbl->action > IWL_MIMO_SWITCH_GI)
                        tbl->action = IWL_MIMO_SWITCH_ANTENNA_A;

                if (tbl->action == start_action)
                        break;
        }

        return 0;
 out:
        tbl->action++;
        if (tbl->action > IWL_MIMO_SWITCH_GI)
                tbl->action = IWL_MIMO_SWITCH_ANTENNA_A;
        return 0;

}

/*
 * Check whether we should continue using same modulation mode, or
 * begin search for a new mode, based on:
 * 1) # tx successes or failures while using this mode
 * 2) # times calling this function
 * 3) elapsed time in this mode (not used, for now)
 */
static void rs_stay_in_table(struct iwl_lq_sta *lq_sta)
{
        struct iwl_scale_tbl_info *tbl;
        int i;
        int active_tbl;
        int flush_interval_passed = 0;
        struct iwl_priv *priv;

        priv = lq_sta->drv;
        active_tbl = lq_sta->active_tbl;

        tbl = &(lq_sta->lq_info[active_tbl]);

        /* If we've been disallowing search, see if we should now allow it */
        if (lq_sta->stay_in_tbl) {

                /* Elapsed time using current modulation mode */
                if (lq_sta->flush_timer)
                        flush_interval_passed =
                            time_after(jiffies,
                                       (unsigned long)(lq_sta->flush_timer +
                                        IWL_RATE_SCALE_FLUSH_INTVL));

                /*
                 * Check if we should allow search for new modulation mode.
                 * If many frames have failed or succeeded, or we've used
                 * this same modulation for a long time, allow search, and
                 * reset history stats that keep track of whether we should
                 * allow a new search.  Also (below) reset all bitmaps and
                 * stats in active history.
                 */
                if ((lq_sta->total_failed > lq_sta->max_failure_limit) ||
                    (lq_sta->total_success > lq_sta->max_success_limit) ||
                    ((!lq_sta->search_better_tbl) && (lq_sta->flush_timer)
                     && (flush_interval_passed))) {
                        IWL_DEBUG_RATE("LQ: stay is expired %d %d %d\n:",
                                     lq_sta->total_failed,
                                     lq_sta->total_success,
                                     flush_interval_passed);

                        /* Allow search for new mode */
                        lq_sta->stay_in_tbl = 0;        /* only place reset */
                        lq_sta->total_failed = 0;
                        lq_sta->total_success = 0;
                        lq_sta->flush_timer = 0;

                /*
                 * Else if we've used this modulation mode enough repetitions
                 * (regardless of elapsed time or success/failure), reset
                 * history bitmaps and rate-specific stats for all rates in
                 * active table.
                 */
                } else {
                        lq_sta->table_count++;
                        if (lq_sta->table_count >=
                            lq_sta->table_count_limit) {
                                lq_sta->table_count = 0;

                                IWL_DEBUG_RATE("LQ: stay in table clear win\n");
                                for (i = 0; i < IWL_RATE_COUNT; i++)
                                        rs_rate_scale_clear_window(
                                                &(tbl->win[i]));
                        }
                }

                /* If transitioning to allow "search", reset all history
                 * bitmaps and stats in active table (this will become the new
                 * "search" table). */
                if (!lq_sta->stay_in_tbl) {
                        for (i = 0; i < IWL_RATE_COUNT; i++)
                                rs_rate_scale_clear_window(&(tbl->win[i]));
                }
        }
}

/*
 * Do rate scaling and search for new modulation mode.
 */
static void rs_rate_scale_perform(struct iwl_priv *priv,
                                  struct net_device *dev,
                                  struct ieee80211_hdr *hdr,
                                  struct sta_info *sta)
{
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct ieee80211_hw *hw = local_to_hw(local);
        struct ieee80211_conf *conf = &hw->conf;
        int low = IWL_RATE_INVALID;
        int high = IWL_RATE_INVALID;
        int index;
        int i;
        struct iwl_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;
        __le16 fc;
        u16 rate_mask;
        u8 update_lq = 0;
        struct iwl_lq_sta *lq_sta;
        struct iwl_scale_tbl_info *tbl, *tbl1;
        u16 rate_scale_index_msk = 0;
        u32 rate;
        u8 is_green = 0;
        u8 active_tbl = 0;
        u8 done_search = 0;
        u16 high_low;
        s32 sr;
        u8 tid = MAX_TID_COUNT;

        IWL_DEBUG_RATE("rate scale calculate new rate for skb\n");

        fc = hdr->frame_control;
        if (!ieee80211_is_data(fc) || is_multicast_ether_addr(hdr->addr1)) {
                /* Send management frames and broadcast/multicast data using
                 * lowest rate. */
                /* TODO: this could probably be improved.. */
                return;
        }

        if (!sta || !sta->rate_ctrl_priv)
                return;

        lq_sta = (struct iwl_lq_sta *)sta->rate_ctrl_priv;
        lq_sta->supp_rates = sta->supp_rates[lq_sta->band];

        tid = rs_tl_add_packet(lq_sta, hdr);

        /*
         * Select rate-scale / modulation-mode table to work with in
         * the rest of this function:  "search" if searching for better
         * modulation mode, or "active" if doing rate scaling within a mode.
         */
        if (!lq_sta->search_better_tbl)
                active_tbl = lq_sta->active_tbl;
        else
                active_tbl = 1 - lq_sta->active_tbl;

        tbl = &(lq_sta->lq_info[active_tbl]);
        is_green = lq_sta->is_green;

        /* current tx rate */
        index = sta->last_txrate_idx;

        IWL_DEBUG_RATE("Rate scale index %d for type %d\n", index,
                       tbl->lq_type);

        /* rates available for this association, and for modulation mode */
        rate_mask = rs_get_supported_rates(lq_sta, hdr, tbl->lq_type);

        IWL_DEBUG_RATE("mask 0x%04X \n", rate_mask);

        /* mask with station rate restriction */
        if (is_legacy(tbl->lq_type)) {
                if (lq_sta->band == IEEE80211_BAND_5GHZ)
                        /* supp_rates has no CCK bits in A mode */
                        rate_scale_index_msk = (u16) (rate_mask &
                                (lq_sta->supp_rates << IWL_FIRST_OFDM_RATE));
                else
                        rate_scale_index_msk = (u16) (rate_mask &
                                                      lq_sta->supp_rates);

        } else
                rate_scale_index_msk = rate_mask;

        if (!rate_scale_index_msk)
                rate_scale_index_msk = rate_mask;

        if (!((1 << index) & rate_scale_index_msk)) {
                IWL_ERROR("Current Rate is not valid\n");
                return;
        }

        /* Get expected throughput table and history window for current rate */
        if (!tbl->expected_tpt) {
                IWL_ERROR("tbl->expected_tpt is NULL\n");
                return;
        }

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

        /*
         * If there is not enough history to calculate actual average
         * throughput, keep analyzing results of more tx frames, without
         * changing rate or mode (bypass most of the rest of this function).
         * Set up new rate table in uCode only if old rate is not supported
         * in current association (use new rate found above).
         */
        fail_count = window->counter - window->success_counter;
        if ((fail_count < IWL_RATE_MIN_FAILURE_TH) &&
                        (window->success_counter < IWL_RATE_MIN_SUCCESS_TH)) {
                IWL_DEBUG_RATE("LQ: still below TH. succ=%d total=%d "
                               "for index %d\n",
                               window->success_counter, window->counter, index);

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

                /* Should we stay with this modulation mode,
                 * or search for a new one? */
                rs_stay_in_table(lq_sta);

                goto out;

        /* Else we have enough samples; calculate estimate of
         * actual average throughput */
        } else {
                /*FIXME:RS remove this else if we don't get this error*/
                if (window->average_tpt != ((window->success_ratio *
                                tbl->expected_tpt[index] + 64) / 128)) {
                        IWL_ERROR("expected_tpt should have been calculated"
                                                                " by now\n");
                        window->average_tpt = ((window->success_ratio *
                                        tbl->expected_tpt[index] + 64) / 128);
                }
        }

        /* If we are searching for better modulation mode, check success. */
        if (lq_sta->search_better_tbl) {

                /* If good success, continue using the "search" mode;
                 * no need to send new link quality command, since we're
                 * continuing to use the setup that we've been trying. */
                if (window->average_tpt > lq_sta->last_tpt) {

                        IWL_DEBUG_RATE("LQ: SWITCHING TO CURRENT TABLE "
                                        "suc=%d cur-tpt=%d old-tpt=%d\n",
                                        window->success_ratio,
                                        window->average_tpt,
                                        lq_sta->last_tpt);

                        if (!is_legacy(tbl->lq_type))
                                lq_sta->enable_counter = 1;

                        /* Swap tables; "search" becomes "active" */
                        lq_sta->active_tbl = active_tbl;
                        current_tpt = window->average_tpt;

                /* Else poor success; go back to mode in "active" table */
                } else {

                        IWL_DEBUG_RATE("LQ: GOING BACK TO THE OLD TABLE "
                                        "suc=%d cur-tpt=%d old-tpt=%d\n",
                                        window->success_ratio,
                                        window->average_tpt,
                                        lq_sta->last_tpt);

                        /* Nullify "search" table */
                        tbl->lq_type = LQ_NONE;

                        /* Revert to "active" table */
                        active_tbl = lq_sta->active_tbl;
                        tbl = &(lq_sta->lq_info[active_tbl]);

                        /* Revert to "active" rate and throughput info */
                        index = iwl_hwrate_to_plcp_idx(tbl->current_rate);
                        current_tpt = lq_sta->last_tpt;

                        /* Need to set up a new rate table in uCode */
                        update_lq = 1;
                }

                /* Either way, we've made a decision; modulation mode
                 * search is done, allow rate adjustment next time. */
                lq_sta->search_better_tbl = 0;
                done_search = 1;        /* Don't switch modes below! */
                goto lq_update;
        }

        /* (Else) not in search of better modulation mode, try for better
         * starting rate, while staying in this mode. */
        high_low = rs_get_adjacent_rate(priv, index, rate_scale_index_msk,
                                        tbl->lq_type);
        low = high_low & 0xff;
        high = (high_low >> 8) & 0xff;

        sr = window->success_ratio;

        /* Collect measured throughputs for current and adjacent rates */
        current_tpt = window->average_tpt;
        if (low != IWL_RATE_INVALID)
                low_tpt = tbl->win[low].average_tpt;
        if (high != IWL_RATE_INVALID)
                high_tpt = tbl->win[high].average_tpt;

        scale_action = 0;

        /* Too many failures, decrease rate */
        if ((sr <= IWL_RATE_DECREASE_TH) || (current_tpt == 0)) {
                IWL_DEBUG_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 == IWL_INVALID_VALUE) &&
                   (high_tpt == IWL_INVALID_VALUE)) {

                if (high != IWL_RATE_INVALID && sr >= IWL_RATE_INCREASE_TH)
                        scale_action = 1;
                else if (low != IWL_RATE_INVALID)
                        scale_action = -1;
        }

        /* 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))
                scale_action = 0;

        /* At least one adjacent rate's throughput is measured,
         * and may have better performance. */
        else {
                /* Higher adjacent rate's throughput is measured */
                if (high_tpt != IWL_INVALID_VALUE) {
                        /* Higher rate has better throughput */
                        if (high_tpt > current_tpt &&
                                        sr >= IWL_RATE_INCREASE_TH) {
                                scale_action = 1;
                        } else {
                                IWL_DEBUG_RATE
                                    ("decrease rate because of high tpt\n");
                                scale_action = -1;
                        }

                /* Lower adjacent rate's throughput is measured */
                } else if (low_tpt != IWL_INVALID_VALUE) {
                        /* Lower rate has better throughput */
                        if (low_tpt > current_tpt) {
                                IWL_DEBUG_RATE
                                    ("decrease rate because of low tpt\n");
                                scale_action = -1;
                        } else if (sr >= IWL_RATE_INCREASE_TH) {
                                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) &&
                    ((sr > IWL_RATE_HIGH_TH) ||
                     (current_tpt > (100 * tbl->expected_tpt[low]))))
                scale_action = 0;

        switch (scale_action) {
        case -1:
                /* Decrease starting rate, update uCode's rate table */
                if (low != IWL_RATE_INVALID) {
                        update_lq = 1;
                        index = low;
                }
                break;
        case 1:
                /* Increase starting rate, update uCode's rate table */
                if (high != IWL_RATE_INVALID) {
                        update_lq = 1;
                        index = high;
                }

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

        IWL_DEBUG_RATE("choose rate scale index %d action %d low %d "
                    "high %d type %d\n",
                     index, scale_action, low, high, tbl->lq_type);

lq_update:
        /* Replace uCode's rate table for the destination station. */
        if (update_lq) {
                rate = rate_n_flags_from_tbl(tbl, index, is_green);
                rs_fill_link_cmd(priv, lq_sta, rate);
                iwl_send_lq_cmd(priv, &lq_sta->lq, CMD_ASYNC);
        }

        /* Should we stay with this modulation mode, or search for a new one? */
        rs_stay_in_table(lq_sta);

        /*
         * Search for new modulation mode if we're:
         * 1)  Not changing rates right now
         * 2)  Not just finishing up a search
         * 3)  Allowing a new search
         */
        if (!update_lq && !done_search && !lq_sta->stay_in_tbl && window->counter) {
                /* Save current throughput to compare with "search" throughput*/
                lq_sta->last_tpt = current_tpt;

                /* Select a new "search" modulation mode to try.
                 * If one is found, set up the new "search" table. */
                if (is_legacy(tbl->lq_type))
                        rs_move_legacy_other(priv, lq_sta, conf, sta, index);
                else if (is_siso(tbl->lq_type))
                        rs_move_siso_to_other(priv, lq_sta, conf, sta, index);
                else
                        rs_move_mimo_to_other(priv, lq_sta, conf, sta, index);

                /* If new "search" mode was selected, set up in uCode table */
                if (lq_sta->search_better_tbl) {
                        /* Access the "search" table, clear its history. */
                        tbl = &(lq_sta->lq_info[(1 - lq_sta->active_tbl)]);
                        for (i = 0; i < IWL_RATE_COUNT; i++)
                                rs_rate_scale_clear_window(&(tbl->win[i]));

                        /* Use new "search" start rate */
                        index = iwl_hwrate_to_plcp_idx(tbl->current_rate);

                        IWL_DEBUG_RATE("Switch current  mcs: %X index: %d\n",
                                     tbl->current_rate, index);
                        rs_fill_link_cmd(priv, lq_sta, tbl->current_rate);
                        iwl_send_lq_cmd(priv, &lq_sta->lq, CMD_ASYNC);
                }

                /* If the "active" (non-search) mode was legacy,
                 * and we've tried switching antennas,
                 * but we haven't been able to try HT modes (not available),
                 * stay with best antenna legacy modulation for a while
                 * before next round of mode comparisons. */
                tbl1 = &(lq_sta->lq_info[lq_sta->active_tbl]);
                if (is_legacy(tbl1->lq_type) &&
                   (!(conf->flags & IEEE80211_CONF_SUPPORT_HT_MODE)) &&
                    (lq_sta->action_counter >= 1)) {
                        lq_sta->action_counter = 0;
                        IWL_DEBUG_RATE("LQ: STAY in legacy table\n");
                        rs_set_stay_in_table(priv, 1, lq_sta);
                }

                /* If we're in an HT mode, and all 3 mode switch actions
                 * have been tried and compared, stay in this best modulation
                 * mode for a while before next round of mode comparisons. */
                if (lq_sta->enable_counter &&
                    (lq_sta->action_counter >= IWL_ACTION_LIMIT)) {
                        if ((lq_sta->last_tpt > IWL_AGG_TPT_THREHOLD) &&
                            (lq_sta->tx_agg_tid_en & (1 << tid)) &&
                            (tid != MAX_TID_COUNT)) {
                                IWL_DEBUG_RATE("try to aggregate tid %d\n", tid);
                                rs_tl_turn_on_agg(priv, tid, lq_sta, sta);
                        }
                        lq_sta->action_counter = 0;
                        rs_set_stay_in_table(priv, 0, lq_sta);
                }

        /*
         * Else, don't search for a new modulation mode.
         * Put new timestamp in stay-in-modulation-mode flush timer if:
         * 1)  Not changing rates right now
         * 2)  Not just finishing up a search
         * 3)  flush timer is empty
         */
        } else {
                if ((!update_lq) && (!done_search) && (!lq_sta->flush_timer))
                        lq_sta->flush_timer = jiffies;
        }

out:
        tbl->current_rate = rate_n_flags_from_tbl(tbl, index, is_green);
        i = index;
        sta->last_txrate_idx = i;

        /* sta->txrate_idx is an index to A mode rates which start
         * at IWL_FIRST_OFDM_RATE
         */
        if (lq_sta->band == IEEE80211_BAND_5GHZ)
                sta->txrate_idx = i - IWL_FIRST_OFDM_RATE;
        else
                sta->txrate_idx = i;

        return;
}


static void rs_initialize_lq(struct iwl_priv *priv,
                             struct ieee80211_conf *conf,
                             struct sta_info *sta)
{
        struct iwl_lq_sta *lq_sta;
        struct iwl_scale_tbl_info *tbl;
        int rate_idx;
        int i;
        u32 rate;
        u8 use_green = rs_use_green(priv, conf);
        u8 active_tbl = 0;
        u8 valid_tx_ant;

        if (!sta || !sta->rate_ctrl_priv)
                goto out;

        lq_sta = (struct iwl_lq_sta *)sta->rate_ctrl_priv;
        i = sta->last_txrate_idx;

        if ((lq_sta->lq.sta_id == 0xff) &&
            (priv->iw_mode == IEEE80211_IF_TYPE_IBSS))
                goto out;

        valid_tx_ant = priv->hw_params.valid_tx_ant;

        if (!lq_sta->search_better_tbl)
                active_tbl = lq_sta->active_tbl;
        else
                active_tbl = 1 - lq_sta->active_tbl;

        tbl = &(lq_sta->lq_info[active_tbl]);

        if ((i < 0) || (i >= IWL_RATE_COUNT))
                i = 0;

        /* FIXME:RS: This is also wrong in 4965 */
        rate = iwl_rates[i].plcp;
        rate |= RATE_MCS_ANT_B_MSK;
        rate &= ~RATE_MCS_ANT_A_MSK;

        if (i >= IWL_FIRST_CCK_RATE && i <= IWL_LAST_CCK_RATE)
                rate |= RATE_MCS_CCK_MSK;

        tbl->ant_type = ANT_B;
        rs_get_tbl_info_from_mcs(rate, priv->band, tbl, &rate_idx);
        if (!rs_is_valid_ant(valid_tx_ant, tbl->ant_type))
            rs_toggle_antenna(valid_tx_ant, &rate, tbl);

        rate = rate_n_flags_from_tbl(tbl, rate_idx, use_green);
        tbl->current_rate = rate;
        rs_set_expected_tpt_table(lq_sta, tbl);
        rs_fill_link_cmd(NULL, lq_sta, rate);
        iwl_send_lq_cmd(priv, &lq_sta->lq, CMD_ASYNC);
 out:
        return;
}

static void rs_get_rate(void *priv_rate, struct net_device *dev,
                        struct ieee80211_supported_band *sband,
                        struct sk_buff *skb,
                        struct rate_selection *sel)
{

        int i;
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct ieee80211_conf *conf = &local->hw.conf;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        struct sta_info *sta;
        __le16 fc;
        struct iwl_priv *priv = (struct iwl_priv *)priv_rate;
        struct iwl_lq_sta *lq_sta;

        IWL_DEBUG_RATE_LIMIT("rate scale calculate new rate for skb\n");

        rcu_read_lock();

        sta = sta_info_get(local, hdr->addr1);

        /* Send management frames and broadcast/multicast data using lowest
         * rate. */
        fc = hdr->frame_control;
        if (!ieee80211_is_data(fc) || is_multicast_ether_addr(hdr->addr1) ||
            !sta || !sta->rate_ctrl_priv) {
                sel->rate_idx = rate_lowest_index(local, sband, sta);
                goto out;
        }

        lq_sta = (struct iwl_lq_sta *)sta->rate_ctrl_priv;
        i = sta->last_txrate_idx;

        if ((priv->iw_mode == IEEE80211_IF_TYPE_IBSS) &&
            !lq_sta->ibss_sta_added) {
                u8 sta_id = iwl_find_station(priv, hdr->addr1);
                DECLARE_MAC_BUF(mac);

                if (sta_id == IWL_INVALID_STATION) {
                        IWL_DEBUG_RATE("LQ: ADD station %s\n",
                                       print_mac(mac, hdr->addr1));
                        sta_id = iwl_add_station_flags(priv, hdr->addr1,
                                                        0, CMD_ASYNC, NULL);
                }
                if ((sta_id != IWL_INVALID_STATION)) {
                        lq_sta->lq.sta_id = sta_id;
                        lq_sta->lq.rs_table[0].rate_n_flags = 0;
                        lq_sta->ibss_sta_added = 1;
                        rs_initialize_lq(priv, conf, sta);
                }
        }

        if ((i < 0) || (i > IWL_RATE_COUNT)) {
                sel->rate_idx = rate_lowest_index(local, sband, sta);
                goto out;
        }

        if (sband->band == IEEE80211_BAND_5GHZ)
                i -= IWL_FIRST_OFDM_RATE;
        sel->rate_idx = i;
out:
        rcu_read_unlock();
}

static void *rs_alloc_sta(void *priv_rate, gfp_t gfp)
{
        struct iwl_lq_sta *lq_sta;
        struct iwl_priv *priv;
        int i, j;

        priv = (struct iwl_priv *)priv_rate;
        IWL_DEBUG_RATE("create station rate scale window\n");

        lq_sta = kzalloc(sizeof(struct iwl_lq_sta), gfp);

        if (lq_sta == NULL)
                return NULL;
        lq_sta->lq.sta_id = 0xff;


        for (j = 0; j < LQ_SIZE; j++)
                for (i = 0; i < IWL_RATE_COUNT; i++)
                        rs_rate_scale_clear_window(&lq_sta->lq_info[j].win[i]);

        return lq_sta;
}

static void rs_rate_init(void *priv_rate, void *priv_sta,
                         struct ieee80211_local *local,
                         struct sta_info *sta)
{
        int i, j;
        struct ieee80211_conf *conf = &local->hw.conf;
        struct ieee80211_supported_band *sband;
        struct iwl_priv *priv = (struct iwl_priv *)priv_rate;
        struct iwl_lq_sta *lq_sta = priv_sta;

        sband = local->hw.wiphy->bands[local->hw.conf.channel->band];

        lq_sta->flush_timer = 0;
        lq_sta->supp_rates = sta->supp_rates[sband->band];
        sta->txrate_idx = 3;
        for (j = 0; j < LQ_SIZE; j++)
                for (i = 0; i < IWL_RATE_COUNT; i++)
                        rs_rate_scale_clear_window(&lq_sta->lq_info[j].win[i]);

        IWL_DEBUG_RATE("LQ: *** rate scale global init ***\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.. */

        lq_sta->ibss_sta_added = 0;
        if (priv->iw_mode == IEEE80211_IF_TYPE_AP) {
                u8 sta_id = iwl_find_station(priv, sta->addr);
                DECLARE_MAC_BUF(mac);

                /* for IBSS the call are from tasklet */
                IWL_DEBUG_RATE("LQ: ADD station %s\n",
                             print_mac(mac, sta->addr));

                if (sta_id == IWL_INVALID_STATION) {
                        IWL_DEBUG_RATE("LQ: ADD station %s\n",
                                       print_mac(mac, sta->addr));
                        sta_id = iwl_add_station_flags(priv, sta->addr,
                                                        0, CMD_ASYNC, NULL);
                }
                if ((sta_id != IWL_INVALID_STATION)) {
                        lq_sta->lq.sta_id = sta_id;
                        lq_sta->lq.rs_table[0].rate_n_flags = 0;
                }
                /* FIXME: this is w/a remove it later */
                priv->assoc_station_added = 1;
        }

        /* Find highest tx rate supported by hardware and destination station */
        for (i = 0; i < sband->n_bitrates; i++)
                if (sta->supp_rates[sband->band] & BIT(i))
                        sta->txrate_idx = i;

        sta->last_txrate_idx = sta->txrate_idx;
        /* For MODE_IEEE80211A, skip over cck rates in global rate table */
        if (local->hw.conf.channel->band == IEEE80211_BAND_5GHZ)
                sta->last_txrate_idx += IWL_FIRST_OFDM_RATE;

        lq_sta->is_dup = 0;
        lq_sta->is_green = rs_use_green(priv, conf);
        lq_sta->active_legacy_rate = priv->active_rate & ~(0x1000);
        lq_sta->active_rate_basic = priv->active_rate_basic;
        lq_sta->band = priv->band;
        /*
         * active_siso_rate mask includes 9 MBits (bit 5), and CCK (bits 0-3),
         * supp_rates[] does not; shift to convert format, force 9 MBits off.
         */
        lq_sta->active_siso_rate = conf->ht_conf.supp_mcs_set[0] << 1;
        lq_sta->active_siso_rate |= conf->ht_conf.supp_mcs_set[0] & 0x1;
        lq_sta->active_siso_rate &= ~((u16)0x2);
        lq_sta->active_siso_rate <<= IWL_FIRST_OFDM_RATE;

        /* Same here */
        lq_sta->active_mimo2_rate = conf->ht_conf.supp_mcs_set[1] << 1;
        lq_sta->active_mimo2_rate |= conf->ht_conf.supp_mcs_set[1] & 0x1;
        lq_sta->active_mimo2_rate &= ~((u16)0x2);
        lq_sta->active_mimo2_rate <<= IWL_FIRST_OFDM_RATE;

        lq_sta->active_mimo3_rate = conf->ht_conf.supp_mcs_set[2] << 1;
        lq_sta->active_mimo3_rate |= conf->ht_conf.supp_mcs_set[2] & 0x1;
        lq_sta->active_mimo3_rate &= ~((u16)0x2);
        lq_sta->active_mimo3_rate <<= IWL_FIRST_OFDM_RATE;

        IWL_DEBUG_RATE("SISO-RATE=%X MIMO2-RATE=%X MIMO3-RATE=%X\n",
                     lq_sta->active_siso_rate,
                     lq_sta->active_mimo2_rate,
                     lq_sta->active_mimo3_rate);

        /* These values will be overriden later */
        lq_sta->lq.general_params.single_stream_ant_msk = ANT_A;
        lq_sta->lq.general_params.dual_stream_ant_msk = ANT_AB;

        /* as default allow aggregation for all tids */
        lq_sta->tx_agg_tid_en = IWL_AGG_ALL_TID;
        lq_sta->drv = priv;

        rs_initialize_lq(priv, conf, sta);
}

static void rs_fill_link_cmd(const struct iwl_priv *priv,
                             struct iwl_lq_sta *lq_sta, u32 new_rate)
{
        struct iwl_scale_tbl_info tbl_type;
        int index = 0;
        int rate_idx;
        int repeat_rate = 0;
        u8 ant_toggle_cnt = 0;
        u8 use_ht_possible = 1;
        u8 valid_tx_ant = 0;
        struct iwl_link_quality_cmd *lq_cmd = &lq_sta->lq;

        /* Override starting rate (index 0) if needed for debug purposes */
        rs_dbgfs_set_mcs(lq_sta, &new_rate, index);

        /* Interpret new_rate (rate_n_flags) */
        memset(&tbl_type, 0, sizeof(tbl_type));
        rs_get_tbl_info_from_mcs(new_rate, lq_sta->band,
                                  &tbl_type, &rate_idx);

        /* How many times should we repeat the initial rate? */
        if (is_legacy(tbl_type.lq_type)) {
                ant_toggle_cnt = 1;
                repeat_rate = IWL_NUMBER_TRY;
        } else {
                repeat_rate = IWL_HT_NUMBER_TRY;
        }

        lq_cmd->general_params.mimo_delimiter =
                        is_mimo(tbl_type.lq_type) ? 1 : 0;

        /* Fill 1st table entry (index 0) */
        lq_cmd->rs_table[index].rate_n_flags = cpu_to_le32(new_rate);

        if (num_of_ant(tbl_type.ant_type) == 1) {
                lq_cmd->general_params.single_stream_ant_msk =
                                                tbl_type.ant_type;
        } else if (num_of_ant(tbl_type.ant_type) == 2) {
                lq_cmd->general_params.dual_stream_ant_msk =
                                                tbl_type.ant_type;
        } /* otherwise we don't modify the existing value */

        index++;
        repeat_rate--;

        if (priv)
                valid_tx_ant = priv->hw_params.valid_tx_ant;

        /* Fill rest of rate table */
        while (index < LINK_QUAL_MAX_RETRY_NUM) {
                /* Repeat initial/next rate.
                 * For legacy IWL_NUMBER_TRY == 1, this loop will not execute.
                 * For HT IWL_HT_NUMBER_TRY == 3, this executes twice. */
                while (repeat_rate > 0 && (index < LINK_QUAL_MAX_RETRY_NUM)) {
                        if (is_legacy(tbl_type.lq_type)) {
                                if (ant_toggle_cnt < NUM_TRY_BEFORE_ANT_TOGGLE)
                                        ant_toggle_cnt++;
                                else if (priv &&
                                         rs_toggle_antenna(valid_tx_ant,
                                                        &new_rate, &tbl_type))
                                        ant_toggle_cnt = 1;
}

                        /* Override next rate if needed for debug purposes */
                        rs_dbgfs_set_mcs(lq_sta, &new_rate, index);

                        /* Fill next table entry */
                        lq_cmd->rs_table[index].rate_n_flags =
                                        cpu_to_le32(new_rate);
                        repeat_rate--;
                        index++;
                }

                rs_get_tbl_info_from_mcs(new_rate, lq_sta->band, &tbl_type,
                                                &rate_idx);

                /* Indicate to uCode which entries might be MIMO.
                 * If initial rate was MIMO, this will finally end up
                 * as (IWL_HT_NUMBER_TRY * 2), after 2nd pass, otherwise 0. */
                if (is_mimo(tbl_type.lq_type))
                        lq_cmd->general_params.mimo_delimiter = index;

                /* Get next rate */
                new_rate = rs_get_lower_rate(lq_sta, &tbl_type, rate_idx,
                                             use_ht_possible);

                /* How many times should we repeat the next rate? */
                if (is_legacy(tbl_type.lq_type)) {
                        if (ant_toggle_cnt < NUM_TRY_BEFORE_ANT_TOGGLE)
                                ant_toggle_cnt++;
                        else if (priv &&
                                 rs_toggle_antenna(valid_tx_ant,
                                                   &new_rate, &tbl_type))
                                ant_toggle_cnt = 1;

                        repeat_rate = IWL_NUMBER_TRY;
                } else {
                        repeat_rate = IWL_HT_NUMBER_TRY;
                }

                /* Don't allow HT rates after next pass.
                 * rs_get_lower_rate() will change type to LQ_A or LQ_G. */
                use_ht_possible = 0;

                /* Override next rate if needed for debug purposes */
                rs_dbgfs_set_mcs(lq_sta, &new_rate, index);

                /* Fill next table entry */
                lq_cmd->rs_table[index].rate_n_flags = cpu_to_le32(new_rate);

                index++;
                repeat_rate--;
        }

        lq_cmd->agg_params.agg_frame_cnt_limit = 64;
        lq_cmd->agg_params.agg_dis_start_th = 3;
        lq_cmd->agg_params.agg_time_limit = cpu_to_le16(4000);
}

static void *rs_alloc(struct ieee80211_local *local)
{
        return local->hw.priv;
}
/* rate scale requires free function to be implemented */
static void rs_free(void *priv_rate)
{
        return;
}

static void rs_clear(void *priv_rate)
{
#ifdef CONFIG_IWLWIFI_DEBUG
        struct iwl_priv *priv = (struct iwl_priv *) priv_rate;

        IWL_DEBUG_RATE("enter\n");

        /* TODO - add rate scale state reset */

        IWL_DEBUG_RATE("leave\n");
#endif /* CONFIG_IWLWIFI_DEBUG */
}

static void rs_free_sta(void *priv_rate, void *priv_sta)
{
        struct iwl_lq_sta *lq_sta = priv_sta;
        struct iwl_priv *priv;

        priv = (struct iwl_priv *)priv_rate;
        IWL_DEBUG_RATE("enter\n");
        kfree(lq_sta);
        IWL_DEBUG_RATE("leave\n");
}


#ifdef CONFIG_MAC80211_DEBUGFS
static int open_file_generic(struct inode *inode, struct file *file)
{
        file->private_data = inode->i_private;
        return 0;
}
static void rs_dbgfs_set_mcs(struct iwl_lq_sta *lq_sta,
                             u32 *rate_n_flags, int index)
{
        struct iwl_priv *priv;

        priv = lq_sta->drv;
        if (lq_sta->dbg_fixed_rate) {
                if (index < 12) {
                        *rate_n_flags = lq_sta->dbg_fixed_rate;
                } else {
                        if (lq_sta->band == IEEE80211_BAND_5GHZ)
                                *rate_n_flags = 0x800D;
                        else
                                *rate_n_flags = 0x820A;
                }
                IWL_DEBUG_RATE("Fixed rate ON\n");
        } else {
                IWL_DEBUG_RATE("Fixed rate OFF\n");
        }
}

static ssize_t rs_sta_dbgfs_scale_table_write(struct file *file,
                        const char __user *user_buf, size_t count, loff_t *ppos)
{
        struct iwl_lq_sta *lq_sta = file->private_data;
        struct iwl_priv *priv;
        char buf[64];
        int buf_size;
        u32 parsed_rate;

        priv = lq_sta->drv;
        memset(buf, 0, sizeof(buf));
        buf_size = min(count, sizeof(buf) -  1);
        if (copy_from_user(buf, user_buf, buf_size))
                return -EFAULT;

        if (sscanf(buf, "%x", &parsed_rate) == 1)
                lq_sta->dbg_fixed_rate = parsed_rate;
        else
                lq_sta->dbg_fixed_rate = 0;

        lq_sta->active_legacy_rate = 0x0FFF;    /* 1 - 54 MBits, includes CCK */
        lq_sta->active_siso_rate   = 0x1FD0;    /* 6 - 60 MBits, no 9, no CCK */
        lq_sta->active_mimo2_rate  = 0x1FD0;    /* 6 - 60 MBits, no 9, no CCK */
        lq_sta->active_mimo3_rate  = 0x1FD0;    /* 6 - 60 MBits, no 9, no CCK */

        IWL_DEBUG_RATE("sta_id %d rate 0x%X\n",
                lq_sta->lq.sta_id, lq_sta->dbg_fixed_rate);

        if (lq_sta->dbg_fixed_rate) {
                rs_fill_link_cmd(NULL, lq_sta, lq_sta->dbg_fixed_rate);
                iwl_send_lq_cmd(lq_sta->drv, &lq_sta->lq, CMD_ASYNC);
        }

        return count;
}

static ssize_t rs_sta_dbgfs_scale_table_read(struct file *file,
                        char __user *user_buf, size_t count, loff_t *ppos)
{
        char buff[1024];
        int desc = 0;
        int i = 0;

        struct iwl_lq_sta *lq_sta = file->private_data;

        desc += sprintf(buff+desc, "sta_id %d\n", lq_sta->lq.sta_id);
        desc += sprintf(buff+desc, "failed=%d success=%d rate=0%X\n",
                        lq_sta->total_failed, lq_sta->total_success,
                        lq_sta->active_legacy_rate);
        desc += sprintf(buff+desc, "fixed rate 0x%X\n",
                        lq_sta->dbg_fixed_rate);
        desc += sprintf(buff+desc, "general:"
                "flags=0x%X mimo-d=%d s-ant0x%x d-ant=0x%x\n",
                lq_sta->lq.general_params.flags,
                lq_sta->lq.general_params.mimo_delimiter,
                lq_sta->lq.general_params.single_stream_ant_msk,
                lq_sta->lq.general_params.dual_stream_ant_msk);

        desc += sprintf(buff+desc, "agg:"
                        "time_limit=%d dist_start_th=%d frame_cnt_limit=%d\n",
                        le16_to_cpu(lq_sta->lq.agg_params.agg_time_limit),
                        lq_sta->lq.agg_params.agg_dis_start_th,
                        lq_sta->lq.agg_params.agg_frame_cnt_limit);

        desc += sprintf(buff+desc,
                        "Start idx [0]=0x%x [1]=0x%x [2]=0x%x [3]=0x%x\n",
                        lq_sta->lq.general_params.start_rate_index[0],
                        lq_sta->lq.general_params.start_rate_index[1],
                        lq_sta->lq.general_params.start_rate_index[2],
                        lq_sta->lq.general_params.start_rate_index[3]);


        for (i = 0; i < LINK_QUAL_MAX_RETRY_NUM; i++)
                desc += sprintf(buff+desc, " rate[%d] 0x%X\n",
                        i, le32_to_cpu(lq_sta->lq.rs_table[i].rate_n_flags));

        return simple_read_from_buffer(user_buf, count, ppos, buff, desc);
}

static const struct file_operations rs_sta_dbgfs_scale_table_ops = {
        .write = rs_sta_dbgfs_scale_table_write,
        .read = rs_sta_dbgfs_scale_table_read,
        .open = open_file_generic,
};
static ssize_t rs_sta_dbgfs_stats_table_read(struct file *file,
                        char __user *user_buf, size_t count, loff_t *ppos)
{
        char buff[1024];
        int desc = 0;
        int i, j;

        struct iwl_lq_sta *lq_sta = file->private_data;
        for (i = 0; i < LQ_SIZE; i++) {
                desc += sprintf(buff+desc, "%s type=%d SGI=%d FAT=%d DUP=%d\n"
                                "rate=0x%X\n",
                                lq_sta->active_tbl == i?"*":"x",
                                lq_sta->lq_info[i].lq_type,
                                lq_sta->lq_info[i].is_SGI,
                                lq_sta->lq_info[i].is_fat,
                                lq_sta->lq_info[i].is_dup,
                                lq_sta->lq_info[i].current_rate);
                for (j = 0; j < IWL_RATE_COUNT; j++) {
                        desc += sprintf(buff+desc,
                                "counter=%d success=%d %%=%d\n",
                                lq_sta->lq_info[i].win[j].counter,
                                lq_sta->lq_info[i].win[j].success_counter,
                                lq_sta->lq_info[i].win[j].success_ratio);
                }
        }
        return simple_read_from_buffer(user_buf, count, ppos, buff, desc);
}

static const struct file_operations rs_sta_dbgfs_stats_table_ops = {
        .read = rs_sta_dbgfs_stats_table_read,
        .open = open_file_generic,
};

static void rs_add_debugfs(void *priv, void *priv_sta,
                                        struct dentry *dir)
{
        struct iwl_lq_sta *lq_sta = priv_sta;
        lq_sta->rs_sta_dbgfs_scale_table_file =
                debugfs_create_file("rate_scale_table", 0600, dir,
                                lq_sta, &rs_sta_dbgfs_scale_table_ops);
        lq_sta->rs_sta_dbgfs_stats_table_file =
                debugfs_create_file("rate_stats_table", 0600, dir,
                        lq_sta, &rs_sta_dbgfs_stats_table_ops);
        lq_sta->rs_sta_dbgfs_tx_agg_tid_en_file =
                debugfs_create_u8("tx_agg_tid_enable", 0600, dir,
                &lq_sta->tx_agg_tid_en);

}

static void rs_remove_debugfs(void *priv, void *priv_sta)
{
        struct iwl_lq_sta *lq_sta = priv_sta;
        debugfs_remove(lq_sta->rs_sta_dbgfs_scale_table_file);
        debugfs_remove(lq_sta->rs_sta_dbgfs_stats_table_file);
        debugfs_remove(lq_sta->rs_sta_dbgfs_tx_agg_tid_en_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,
        .clear = rs_clear,
        .alloc = rs_alloc,
        .free = rs_free,
        .alloc_sta = rs_alloc_sta,
        .free_sta = rs_free_sta,
#ifdef CONFIG_MAC80211_DEBUGFS
        .add_sta_debugfs = rs_add_debugfs,
        .remove_sta_debugfs = rs_remove_debugfs,
#endif
};

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

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