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 "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;

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

static void rs_rate_scale_perform(struct iwl_priv *priv,
				   struct ieee80211_hdr *hdr,
				   struct ieee80211_sta *sta,
				   struct iwl_lq_sta *lq_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 separate 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 ieee80211_sta *sta)
{
	if (rs_tl_get_load(lq_data, tid) > IWL_AGG_LOAD_THRESHOLD) {
		IWL_DEBUG_HT("Starting Tx agg: STA: %pM tid: %d\n",
				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 ieee80211_sta *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_r, struct ieee80211_supported_band *sband,
			 struct ieee80211_sta *sta, void *priv_sta,
			 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 ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	struct iwl_priv *priv = (struct iwl_priv *)priv_r;
	struct ieee80211_hw *hw = priv->hw;
	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.rates[0].count - 1;

	if (retries > 15)
		retries = 15;

	lq_sta = (struct iwl_lq_sta *)priv_sta;

	if ((priv->iw_mode == NL80211_IFTYPE_ADHOC) &&
	    !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->status.rates[0].idx < 0) ||
	    (tbl_type.is_SGI != !!(info->status.rates[0].flags & IEEE80211_TX_RC_SHORT_GI)) ||
	    (tbl_type.is_fat != !!(info->status.rates[0].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)) ||
	    (tbl_type.is_dup != !!(info->status.rates[0].flags & IEEE80211_TX_RC_DUP_DATA)) ||
	    (tbl_type.ant_type != info->antenna_sel_tx) ||
	    (!!(tx_rate & RATE_MCS_HT_MSK) != !!(info->status.rates[0].flags & IEEE80211_TX_RC_MCS)) ||
	    (!!(tx_rate & RATE_MCS_GF_MSK) != !!(info->status.rates[0].flags & IEEE80211_TX_RC_GREEN_FIELD)) ||
	    (hw->wiphy->bands[priv->band]->bitrates[rs_index].bitrate !=
	     hw->wiphy->bands[info->band]->bitrates[info->status.rates[0].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, hdr, sta, lq_sta);
out:
	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 ieee80211_sta *sta,
			     struct iwl_scale_tbl_info *tbl, int index)
{
	u16 rate_mask;
	s32 rate;
	s8 is_green = lq_sta->is_green;

	if (!conf->ht.enabled || !sta->ht_cap.ht_supported)
		return -1;

	if (((sta->ht_cap.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 ieee80211_sta *sta,
			     struct iwl_scale_tbl_info *tbl, int index)
{
	u16 rate_mask;
	u8 is_green = lq_sta->is_green;
	s32 rate;

	if (!conf->ht.enabled || !sta->ht_cap.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 ieee80211_sta *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;
	u8 tx_chains_num = priv->hw_params.tx_chains_num;
	int ret = 0;

	for (; ;) {
		switch (tbl->action) {
		case IWL_LEGACY_SWITCH_ANTENNA1:
		case IWL_LEGACY_SWITCH_ANTENNA2:
			IWL_DEBUG_RATE("LQ: Legacy toggle Antenna\n");

			lq_sta->action_counter++;

			if ((tbl->action == IWL_LEGACY_SWITCH_ANTENNA1 &&
							tx_chains_num <= 1) ||
			    (tbl->action == IWL_LEGACY_SWITCH_ANTENNA2 &&
							tx_chains_num <= 2))
				break;

			/* 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)) {
				rs_set_expected_tpt_table(lq_sta, search_tbl);
				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->action_counter = 0;
				goto out;
			}

			break;
		case IWL_LEGACY_SWITCH_MIMO2_AB:
		case IWL_LEGACY_SWITCH_MIMO2_AC:
		case IWL_LEGACY_SWITCH_MIMO2_BC:
			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;

			if (tbl->action == IWL_LEGACY_SWITCH_MIMO2_AB)
				search_tbl->ant_type = ANT_AB;
			else if (tbl->action == IWL_LEGACY_SWITCH_MIMO2_AC)
				search_tbl->ant_type = ANT_AC;
			else
				search_tbl->ant_type = ANT_BC;

			if (!rs_is_valid_ant(valid_tx_ant, search_tbl->ant_type))
				break;

			ret = rs_switch_to_mimo2(priv, lq_sta, conf, sta,
						 search_tbl, index);
			if (!ret) {
				lq_sta->action_counter = 0;
				goto out;
			}
			break;
		}
		tbl->action++;
		if (tbl->action > IWL_LEGACY_SWITCH_MIMO2_BC)
			tbl->action = IWL_LEGACY_SWITCH_ANTENNA1;

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

	}
	search_tbl->lq_type = LQ_NONE;
	return 0;

out:
	lq_sta->search_better_tbl = 1;
	tbl->action++;
	if (tbl->action > IWL_LEGACY_SWITCH_MIMO2_BC)
		tbl->action = IWL_LEGACY_SWITCH_ANTENNA1;
	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 ieee80211_sta *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;
	u8 tx_chains_num = priv->hw_params.tx_chains_num;
	int ret;

	for (;;) {
		lq_sta->action_counter++;
		switch (tbl->action) {
		case IWL_SISO_SWITCH_ANTENNA1:
		case IWL_SISO_SWITCH_ANTENNA2:
			IWL_DEBUG_RATE("LQ: SISO toggle Antenna\n");

			if ((tbl->action == IWL_SISO_SWITCH_ANTENNA1 &&
							tx_chains_num <= 1) ||
			    (tbl->action == IWL_SISO_SWITCH_ANTENNA2 &&
							tx_chains_num <= 2))
				break;

			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))
				goto out;
			break;
		case IWL_SISO_SWITCH_MIMO2_AB:
		case IWL_SISO_SWITCH_MIMO2_AC:
		case IWL_SISO_SWITCH_MIMO2_BC:
			IWL_DEBUG_RATE("LQ: SISO switch to MIMO2\n");
			memcpy(search_tbl, tbl, sz);
			search_tbl->is_SGI = 0;

			if (tbl->action == IWL_SISO_SWITCH_MIMO2_AB)
				search_tbl->ant_type = ANT_AB;
			else if (tbl->action == IWL_SISO_SWITCH_MIMO2_AC)
				search_tbl->ant_type = ANT_AC;
			else
				search_tbl->ant_type = ANT_BC;

			if (!rs_is_valid_ant(valid_tx_ant, search_tbl->ant_type))
				break;

			ret = rs_switch_to_mimo2(priv, lq_sta, conf, sta,
						 search_tbl, index);
			if (!ret)
				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);
			goto out;
		}
		tbl->action++;
		if (tbl->action > IWL_SISO_SWITCH_GI)
			tbl->action = IWL_SISO_SWITCH_ANTENNA1;

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

 out:
	lq_sta->search_better_tbl = 1;
	tbl->action++;
	if (tbl->action > IWL_SISO_SWITCH_GI)
		tbl->action = IWL_SISO_SWITCH_ANTENNA1;
	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 ieee80211_sta *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)]);
	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;
	u8 tx_chains_num = priv->hw_params.tx_chains_num;
	int ret;

	for (;;) {
		lq_sta->action_counter++;
		switch (tbl->action) {
		case IWL_MIMO2_SWITCH_ANTENNA1:
		case IWL_MIMO2_SWITCH_ANTENNA2:
			IWL_DEBUG_RATE("LQ: MIMO toggle Antennas\n");

			if (tx_chains_num <= 2)
				break;

			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))
				goto out;
			break;
		case IWL_MIMO2_SWITCH_SISO_A:
		case IWL_MIMO2_SWITCH_SISO_B:
		case IWL_MIMO2_SWITCH_SISO_C:
			IWL_DEBUG_RATE("LQ: MIMO2 switch to SISO\n");

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

			if (tbl->action == IWL_MIMO2_SWITCH_SISO_A)
				search_tbl->ant_type = ANT_A;
			else if (tbl->action == IWL_MIMO2_SWITCH_SISO_B)
				search_tbl->ant_type = ANT_B;
			else
				search_tbl->ant_type = ANT_C;

			if (!rs_is_valid_ant(valid_tx_ant, search_tbl->ant_type))
				break;

			ret = rs_switch_to_siso(priv, lq_sta, conf, sta,
						 search_tbl, index);
			if (!ret)
				goto out;

			break;

		case IWL_MIMO2_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);
			goto out;

		}
		tbl->action++;
		if (tbl->action > IWL_MIMO2_SWITCH_GI)
			tbl->action = IWL_MIMO2_SWITCH_ANTENNA1;

		if (tbl->action == start_action)
			break;
	}
	search_tbl->lq_type = LQ_NONE;
	return 0;
 out:
	lq_sta->search_better_tbl = 1;
	tbl->action++;
	if (tbl->action > IWL_MIMO2_SWITCH_GI)
		tbl->action = IWL_MIMO2_SWITCH_ANTENNA1;
	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 ieee80211_hdr *hdr,
				  struct ieee80211_sta *sta,
				  struct iwl_lq_sta *lq_sta)
{
	struct ieee80211_hw *hw = priv->hw;
	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_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 || !lq_sta)
		return;

	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 = lq_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 */

	BUG_ON(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 NEW 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->ht.enabled &&
		    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;
	lq_sta->last_txrate_idx = i;

	return;
}


static void rs_initialize_lq(struct iwl_priv *priv,
			     struct ieee80211_conf *conf,
			     struct ieee80211_sta *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 || !lq_sta)
		goto out;

	i = lq_sta->last_txrate_idx;

	if ((lq_sta->lq.sta_id == 0xff) &&
	    (priv->iw_mode == NL80211_IFTYPE_ADHOC))
		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_r, struct ieee80211_sta *sta, void *priv_sta,
			struct ieee80211_tx_rate_control *txrc)
{

	int i;
	struct sk_buff *skb = txrc->skb;
	struct ieee80211_supported_band *sband = txrc->sband;
	struct iwl_priv *priv = (struct iwl_priv *)priv_r;
	struct ieee80211_conf *conf = &priv->hw->conf;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	__le16 fc;
	struct iwl_lq_sta *lq_sta;

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

	/* 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 || !priv_sta) {
		info->control.rates[0].idx = rate_lowest_index(sband, sta);
		return;
	}

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

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

		if (sta_id == IWL_INVALID_STATION) {
			IWL_DEBUG_RATE("LQ: ADD station %pM\n",
				       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, lq_sta);
		}
	}

	if ((i < 0) || (i > IWL_RATE_COUNT)) {
		info->control.rates[0].idx = rate_lowest_index(sband, sta);
		return;
	}

	if (sband->band == IEEE80211_BAND_5GHZ)
		i -= IWL_FIRST_OFDM_RATE;
	info->control.rates[0].idx = i;
}

static void *rs_alloc_sta(void *priv_rate, struct ieee80211_sta *sta,
			  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_r, struct ieee80211_supported_band *sband,
			 struct ieee80211_sta *sta, void *priv_sta)
{
	int i, j;
	struct iwl_priv *priv = (struct iwl_priv *)priv_r;
	struct ieee80211_conf *conf = &priv->hw->conf;
	struct iwl_lq_sta *lq_sta = priv_sta;

	lq_sta->flush_timer = 0;
	lq_sta->supp_rates = sta->supp_rates[sband->band];
	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 station 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 == NL80211_IFTYPE_AP) {
		u8 sta_id = iwl_find_station(priv, sta->addr);

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

		if (sta_id == IWL_INVALID_STATION) {
			IWL_DEBUG_RATE("LQ: ADD station %pM\n", 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 */
	lq_sta->last_txrate_idx = 3;
	for (i = 0; i < sband->n_bitrates; i++)
		if (sta->supp_rates[sband->band] & BIT(i))
			lq_sta->last_txrate_idx = i;

	/* For MODE_IEEE80211A, skip over cck rates in global rate table */
	if (sband->band == IEEE80211_BAND_5GHZ)
		lq_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 = sta->ht_cap.mcs.rx_mask[0] << 1;
	lq_sta->active_siso_rate |= sta->ht_cap.mcs.rx_mask[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 = sta->ht_cap.mcs.rx_mask[1] << 1;
	lq_sta->active_mimo2_rate |= sta->ht_cap.mcs.rx_mask[1] & 0x1;
	lq_sta->active_mimo2_rate &= ~((u16)0x2);
	lq_sta->active_mimo2_rate <<= IWL_FIRST_OFDM_RATE;

	lq_sta->active_mimo3_rate = sta->ht_cap.mcs.rx_mask[2] << 1;
	lq_sta->active_mimo3_rate |= sta->ht_cap.mcs.rx_mask[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 overridden 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, lq_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_hw *hw, struct dentry *debugfsdir)
{
	return hw->priv;
}
/* rate scale requires free function to be implemented */
static void rs_free(void *priv_rate)
{
	return;
}

static void rs_free_sta(void *priv_r, struct ieee80211_sta *sta,
			void *priv_sta)
{
	struct iwl_lq_sta *lq_sta = priv_sta;
	struct iwl_priv *priv __maybe_unused = priv_r;

	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,
	.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);
}