4965-calib.c

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/******************************************************************************
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110,
 * USA
 *
 * The full GNU General Public License is included in this distribution
 * in the file called LICENSE.GPL.
 *
 * Contact Information:
 *  Intel Linux Wireless <[email protected]>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 * BSD LICENSE
 *
 * Copyright(c) 2005 - 2011 Intel Corporation. All rights reserved.
 * All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
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 *
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 *****************************************************************************/

#include <linux/slab.h>
#include <net/mac80211.h>

#include "common.h"
#include "4965.h"

/*****************************************************************************
 * INIT calibrations framework
 *****************************************************************************/

struct stats_general_data {
    u32 beacon_silence_rssi_a;
    u32 beacon_silence_rssi_b;
    u32 beacon_silence_rssi_c;
    u32 beacon_energy_a;
    u32 beacon_energy_b;
    u32 beacon_energy_c;
};

/*****************************************************************************
 * RUNTIME calibrations framework
 *****************************************************************************/

/* "false alarms" are signals that our DSP tries to lock onto,
 *   but then determines that they are either noise, or transmissions
 *   from a distant wireless network (also "noise", really) that get
 *   "stepped on" by stronger transmissions within our own network.
 * This algorithm attempts to set a sensitivity level that is high
 *   enough to receive all of our own network traffic, but not so
 *   high that our DSP gets too busy trying to lock onto non-network
 *   activity/noise. */
static int
il4965_sens_energy_cck(struct il_priv *il, u32 norm_fa, u32 rx_enable_time,
               struct stats_general_data *rx_info)
{
    u32 max_nrg_cck = 0;
    int i = 0;
    u8 max_silence_rssi = 0;
    u32 silence_ref = 0;
    u8 silence_rssi_a = 0;
    u8 silence_rssi_b = 0;
    u8 silence_rssi_c = 0;
    u32 val;

    /* "false_alarms" values below are cross-multiplications to assess the
     *   numbers of false alarms within the measured period of actual Rx
     *   (Rx is off when we're txing), vs the min/max expected false alarms
     *   (some should be expected if rx is sensitive enough) in a
     *   hypothetical listening period of 200 time units (TU), 204.8 msec:
     *
     * MIN_FA/fixed-time < false_alarms/actual-rx-time < MAX_FA/beacon-time
     *
     * */
    u32 false_alarms = norm_fa * 200 * 1024;
    u32 max_false_alarms = MAX_FA_CCK * rx_enable_time;
    u32 min_false_alarms = MIN_FA_CCK * rx_enable_time;
    struct il_sensitivity_data *data = NULL;
    const struct il_sensitivity_ranges *ranges = il->hw_params.sens;

    data = &(il->sensitivity_data);

    data->nrg_auto_corr_silence_diff = 0;

    /* Find max silence rssi among all 3 receivers.
     * This is background noise, which may include transmissions from other
     *    networks, measured during silence before our network's beacon */
    silence_rssi_a =
        (u8) ((rx_info->beacon_silence_rssi_a & ALL_BAND_FILTER) >> 8);
    silence_rssi_b =
        (u8) ((rx_info->beacon_silence_rssi_b & ALL_BAND_FILTER) >> 8);
    silence_rssi_c =
        (u8) ((rx_info->beacon_silence_rssi_c & ALL_BAND_FILTER) >> 8);

    val = max(silence_rssi_b, silence_rssi_c);
    max_silence_rssi = max(silence_rssi_a, (u8) val);

    /* Store silence rssi in 20-beacon history table */
    data->nrg_silence_rssi[data->nrg_silence_idx] = max_silence_rssi;
    data->nrg_silence_idx++;
    if (data->nrg_silence_idx >= NRG_NUM_PREV_STAT_L)
        data->nrg_silence_idx = 0;

    /* Find max silence rssi across 20 beacon history */
    for (i = 0; i < NRG_NUM_PREV_STAT_L; i++) {
        val = data->nrg_silence_rssi[i];
        silence_ref = max(silence_ref, val);
    }
    D_CALIB("silence a %u, b %u, c %u, 20-bcn max %u\n", silence_rssi_a,
        silence_rssi_b, silence_rssi_c, silence_ref);

    /* Find max rx energy (min value!) among all 3 receivers,
     *   measured during beacon frame.
     * Save it in 10-beacon history table. */
    i = data->nrg_energy_idx;
    val = min(rx_info->beacon_energy_b, rx_info->beacon_energy_c);
    data->nrg_value[i] = min(rx_info->beacon_energy_a, val);

    data->nrg_energy_idx++;
    if (data->nrg_energy_idx >= 10)
        data->nrg_energy_idx = 0;

    /* Find min rx energy (max value) across 10 beacon history.
     * This is the minimum signal level that we want to receive well.
     * Add backoff (margin so we don't miss slightly lower energy frames).
     * This establishes an upper bound (min value) for energy threshold. */
    max_nrg_cck = data->nrg_value[0];
    for (i = 1; i < 10; i++)
        max_nrg_cck = (u32) max(max_nrg_cck, (data->nrg_value[i]));
    max_nrg_cck += 6;

    D_CALIB("rx energy a %u, b %u, c %u, 10-bcn max/min %u\n",
        rx_info->beacon_energy_a, rx_info->beacon_energy_b,
        rx_info->beacon_energy_c, max_nrg_cck - 6);

    /* Count number of consecutive beacons with fewer-than-desired
     *   false alarms. */
    if (false_alarms < min_false_alarms)
        data->num_in_cck_no_fa++;
    else
        data->num_in_cck_no_fa = 0;
    D_CALIB("consecutive bcns with few false alarms = %u\n",
        data->num_in_cck_no_fa);

    /* If we got too many false alarms this time, reduce sensitivity */
    if (false_alarms > max_false_alarms &&
        data->auto_corr_cck > AUTO_CORR_MAX_TH_CCK) {
        D_CALIB("norm FA %u > max FA %u\n", false_alarms,
            max_false_alarms);
        D_CALIB("... reducing sensitivity\n");
        data->nrg_curr_state = IL_FA_TOO_MANY;
        /* Store for "fewer than desired" on later beacon */
        data->nrg_silence_ref = silence_ref;

        /* increase energy threshold (reduce nrg value)
         *   to decrease sensitivity */
        data->nrg_th_cck = data->nrg_th_cck - NRG_STEP_CCK;
        /* Else if we got fewer than desired, increase sensitivity */
    } else if (false_alarms < min_false_alarms) {
        data->nrg_curr_state = IL_FA_TOO_FEW;

        /* Compare silence level with silence level for most recent
         *   healthy number or too many false alarms */
        data->nrg_auto_corr_silence_diff =
            (s32) data->nrg_silence_ref - (s32) silence_ref;

        D_CALIB("norm FA %u < min FA %u, silence diff %d\n",
            false_alarms, min_false_alarms,
            data->nrg_auto_corr_silence_diff);

        /* Increase value to increase sensitivity, but only if:
         * 1a) previous beacon did *not* have *too many* false alarms
         * 1b) AND there's a significant difference in Rx levels
         *      from a previous beacon with too many, or healthy # FAs
         * OR 2) We've seen a lot of beacons (100) with too few
         *       false alarms */
        if (data->nrg_prev_state != IL_FA_TOO_MANY &&
            (data->nrg_auto_corr_silence_diff > NRG_DIFF ||
             data->num_in_cck_no_fa > MAX_NUMBER_CCK_NO_FA)) {

            D_CALIB("... increasing sensitivity\n");
            /* Increase nrg value to increase sensitivity */
            val = data->nrg_th_cck + NRG_STEP_CCK;
            data->nrg_th_cck = min((u32) ranges->min_nrg_cck, val);
        } else {
            D_CALIB("... but not changing sensitivity\n");
        }

        /* Else we got a healthy number of false alarms, keep status quo */
    } else {
        D_CALIB(" FA in safe zone\n");
        data->nrg_curr_state = IL_FA_GOOD_RANGE;

        /* Store for use in "fewer than desired" with later beacon */
        data->nrg_silence_ref = silence_ref;

        /* If previous beacon had too many false alarms,
         *   give it some extra margin by reducing sensitivity again
         *   (but don't go below measured energy of desired Rx) */
        if (IL_FA_TOO_MANY == data->nrg_prev_state) {
            D_CALIB("... increasing margin\n");
            if (data->nrg_th_cck > (max_nrg_cck + NRG_MARGIN))
                data->nrg_th_cck -= NRG_MARGIN;
            else
                data->nrg_th_cck = max_nrg_cck;
        }
    }

    /* Make sure the energy threshold does not go above the measured
     * energy of the desired Rx signals (reduced by backoff margin),
     * or else we might start missing Rx frames.
     * Lower value is higher energy, so we use max()!
     */
    data->nrg_th_cck = max(max_nrg_cck, data->nrg_th_cck);
    D_CALIB("new nrg_th_cck %u\n", data->nrg_th_cck);

    data->nrg_prev_state = data->nrg_curr_state;

    /* Auto-correlation CCK algorithm */
    if (false_alarms > min_false_alarms) {

        /* increase auto_corr values to decrease sensitivity
         * so the DSP won't be disturbed by the noise
         */
        if (data->auto_corr_cck < AUTO_CORR_MAX_TH_CCK)
            data->auto_corr_cck = AUTO_CORR_MAX_TH_CCK + 1;
        else {
            val = data->auto_corr_cck + AUTO_CORR_STEP_CCK;
            data->auto_corr_cck =
                min((u32) ranges->auto_corr_max_cck, val);
        }
        val = data->auto_corr_cck_mrc + AUTO_CORR_STEP_CCK;
        data->auto_corr_cck_mrc =
            min((u32) ranges->auto_corr_max_cck_mrc, val);
    } else if (false_alarms < min_false_alarms &&
           (data->nrg_auto_corr_silence_diff > NRG_DIFF ||
            data->num_in_cck_no_fa > MAX_NUMBER_CCK_NO_FA)) {

        /* Decrease auto_corr values to increase sensitivity */
        val = data->auto_corr_cck - AUTO_CORR_STEP_CCK;
        data->auto_corr_cck = max((u32) ranges->auto_corr_min_cck, val);
        val = data->auto_corr_cck_mrc - AUTO_CORR_STEP_CCK;
        data->auto_corr_cck_mrc =
            max((u32) ranges->auto_corr_min_cck_mrc, val);
    }

    return 0;
}

static int
il4965_sens_auto_corr_ofdm(struct il_priv *il, u32 norm_fa, u32 rx_enable_time)
{
    u32 val;
    u32 false_alarms = norm_fa * 200 * 1024;
    u32 max_false_alarms = MAX_FA_OFDM * rx_enable_time;
    u32 min_false_alarms = MIN_FA_OFDM * rx_enable_time;
    struct il_sensitivity_data *data = NULL;
    const struct il_sensitivity_ranges *ranges = il->hw_params.sens;

    data = &(il->sensitivity_data);

    /* If we got too many false alarms this time, reduce sensitivity */
    if (false_alarms > max_false_alarms) {

        D_CALIB("norm FA %u > max FA %u)\n", false_alarms,
            max_false_alarms);

        val = data->auto_corr_ofdm + AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm =
            min((u32) ranges->auto_corr_max_ofdm, val);

        val = data->auto_corr_ofdm_mrc + AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm_mrc =
            min((u32) ranges->auto_corr_max_ofdm_mrc, val);

        val = data->auto_corr_ofdm_x1 + AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm_x1 =
            min((u32) ranges->auto_corr_max_ofdm_x1, val);

        val = data->auto_corr_ofdm_mrc_x1 + AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm_mrc_x1 =
            min((u32) ranges->auto_corr_max_ofdm_mrc_x1, val);
    }

    /* Else if we got fewer than desired, increase sensitivity */
    else if (false_alarms < min_false_alarms) {

        D_CALIB("norm FA %u < min FA %u\n", false_alarms,
            min_false_alarms);

        val = data->auto_corr_ofdm - AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm =
            max((u32) ranges->auto_corr_min_ofdm, val);

        val = data->auto_corr_ofdm_mrc - AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm_mrc =
            max((u32) ranges->auto_corr_min_ofdm_mrc, val);

        val = data->auto_corr_ofdm_x1 - AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm_x1 =
            max((u32) ranges->auto_corr_min_ofdm_x1, val);

        val = data->auto_corr_ofdm_mrc_x1 - AUTO_CORR_STEP_OFDM;
        data->auto_corr_ofdm_mrc_x1 =
            max((u32) ranges->auto_corr_min_ofdm_mrc_x1, val);
    } else {
        D_CALIB("min FA %u < norm FA %u < max FA %u OK\n",
            min_false_alarms, false_alarms, max_false_alarms);
    }
    return 0;
}

static void
il4965_prepare_legacy_sensitivity_tbl(struct il_priv *il,
                      struct il_sensitivity_data *data,
                      __le16 *tbl)
{
    tbl[HD_AUTO_CORR32_X4_TH_ADD_MIN_IDX] =
        cpu_to_le16((u16) data->auto_corr_ofdm);
    tbl[HD_AUTO_CORR32_X4_TH_ADD_MIN_MRC_IDX] =
        cpu_to_le16((u16) data->auto_corr_ofdm_mrc);
    tbl[HD_AUTO_CORR32_X1_TH_ADD_MIN_IDX] =
        cpu_to_le16((u16) data->auto_corr_ofdm_x1);
    tbl[HD_AUTO_CORR32_X1_TH_ADD_MIN_MRC_IDX] =
        cpu_to_le16((u16) data->auto_corr_ofdm_mrc_x1);

    tbl[HD_AUTO_CORR40_X4_TH_ADD_MIN_IDX] =
        cpu_to_le16((u16) data->auto_corr_cck);
    tbl[HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_IDX] =
        cpu_to_le16((u16) data->auto_corr_cck_mrc);

    tbl[HD_MIN_ENERGY_CCK_DET_IDX] = cpu_to_le16((u16) data->nrg_th_cck);
    tbl[HD_MIN_ENERGY_OFDM_DET_IDX] = cpu_to_le16((u16) data->nrg_th_ofdm);

    tbl[HD_BARKER_CORR_TH_ADD_MIN_IDX] =
        cpu_to_le16(data->barker_corr_th_min);
    tbl[HD_BARKER_CORR_TH_ADD_MIN_MRC_IDX] =
        cpu_to_le16(data->barker_corr_th_min_mrc);
    tbl[HD_OFDM_ENERGY_TH_IN_IDX] = cpu_to_le16(data->nrg_th_cca);

    D_CALIB("ofdm: ac %u mrc %u x1 %u mrc_x1 %u thresh %u\n",
        data->auto_corr_ofdm, data->auto_corr_ofdm_mrc,
        data->auto_corr_ofdm_x1, data->auto_corr_ofdm_mrc_x1,
        data->nrg_th_ofdm);

    D_CALIB("cck: ac %u mrc %u thresh %u\n", data->auto_corr_cck,
        data->auto_corr_cck_mrc, data->nrg_th_cck);
}

/* Prepare a C_SENSITIVITY, send to uCode if values have changed */
static int
il4965_sensitivity_write(struct il_priv *il)
{
    struct il_sensitivity_cmd cmd;
    struct il_sensitivity_data *data = NULL;
    struct il_host_cmd cmd_out = {
        .id = C_SENSITIVITY,
        .len = sizeof(struct il_sensitivity_cmd),
        .flags = CMD_ASYNC,
        .data = &cmd,
    };

    data = &(il->sensitivity_data);

    memset(&cmd, 0, sizeof(cmd));

    il4965_prepare_legacy_sensitivity_tbl(il, data, &cmd.table[0]);

    /* Update uCode's "work" table, and copy it to DSP */
    cmd.control = C_SENSITIVITY_CONTROL_WORK_TBL;

    /* Don't send command to uCode if nothing has changed */
    if (!memcmp
        (&cmd.table[0], &(il->sensitivity_tbl[0]),
         sizeof(u16) * HD_TBL_SIZE)) {
        D_CALIB("No change in C_SENSITIVITY\n");
        return 0;
    }

    /* Copy table for comparison next time */
    memcpy(&(il->sensitivity_tbl[0]), &(cmd.table[0]),
           sizeof(u16) * HD_TBL_SIZE);

    return il_send_cmd(il, &cmd_out);
}

void
il4965_init_sensitivity(struct il_priv *il)
{
    int ret = 0;
    int i;
    struct il_sensitivity_data *data = NULL;
    const struct il_sensitivity_ranges *ranges = il->hw_params.sens;

    if (il->disable_sens_cal)
        return;

    D_CALIB("Start il4965_init_sensitivity\n");

    /* Clear driver's sensitivity algo data */
    data = &(il->sensitivity_data);

    if (ranges == NULL)
        return;

    memset(data, 0, sizeof(struct il_sensitivity_data));

    data->num_in_cck_no_fa = 0;
    data->nrg_curr_state = IL_FA_TOO_MANY;
    data->nrg_prev_state = IL_FA_TOO_MANY;
    data->nrg_silence_ref = 0;
    data->nrg_silence_idx = 0;
    data->nrg_energy_idx = 0;

    for (i = 0; i < 10; i++)
        data->nrg_value[i] = 0;

    for (i = 0; i < NRG_NUM_PREV_STAT_L; i++)
        data->nrg_silence_rssi[i] = 0;

    data->auto_corr_ofdm = ranges->auto_corr_min_ofdm;
    data->auto_corr_ofdm_mrc = ranges->auto_corr_min_ofdm_mrc;
    data->auto_corr_ofdm_x1 = ranges->auto_corr_min_ofdm_x1;
    data->auto_corr_ofdm_mrc_x1 = ranges->auto_corr_min_ofdm_mrc_x1;
    data->auto_corr_cck = AUTO_CORR_CCK_MIN_VAL_DEF;
    data->auto_corr_cck_mrc = ranges->auto_corr_min_cck_mrc;
    data->nrg_th_cck = ranges->nrg_th_cck;
    data->nrg_th_ofdm = ranges->nrg_th_ofdm;
    data->barker_corr_th_min = ranges->barker_corr_th_min;
    data->barker_corr_th_min_mrc = ranges->barker_corr_th_min_mrc;
    data->nrg_th_cca = ranges->nrg_th_cca;

    data->last_bad_plcp_cnt_ofdm = 0;
    data->last_fa_cnt_ofdm = 0;
    data->last_bad_plcp_cnt_cck = 0;
    data->last_fa_cnt_cck = 0;

    ret |= il4965_sensitivity_write(il);
    D_CALIB("<<return 0x%X\n", ret);
}

void
il4965_sensitivity_calibration(struct il_priv *il, void *resp)
{
    u32 rx_enable_time;
    u32 fa_cck;
    u32 fa_ofdm;
    u32 bad_plcp_cck;
    u32 bad_plcp_ofdm;
    u32 norm_fa_ofdm;
    u32 norm_fa_cck;
    struct il_sensitivity_data *data = NULL;
    struct stats_rx_non_phy *rx_info;
    struct stats_rx_phy *ofdm, *cck;
    unsigned long flags;
    struct stats_general_data statis;

    if (il->disable_sens_cal)
        return;

    data = &(il->sensitivity_data);

    if (!il_is_any_associated(il)) {
        D_CALIB("<< - not associated\n");
        return;
    }

    spin_lock_irqsave(&il->lock, flags);

    rx_info = &(((struct il_notif_stats *)resp)->rx.general);
    ofdm = &(((struct il_notif_stats *)resp)->rx.ofdm);
    cck = &(((struct il_notif_stats *)resp)->rx.cck);

    if (rx_info->interference_data_flag != INTERFERENCE_DATA_AVAILABLE) {
        D_CALIB("<< invalid data.\n");
        spin_unlock_irqrestore(&il->lock, flags);
        return;
    }

    /* Extract Statistics: */
    rx_enable_time = le32_to_cpu(rx_info->channel_load);
    fa_cck = le32_to_cpu(cck->false_alarm_cnt);
    fa_ofdm = le32_to_cpu(ofdm->false_alarm_cnt);
    bad_plcp_cck = le32_to_cpu(cck->plcp_err);
    bad_plcp_ofdm = le32_to_cpu(ofdm->plcp_err);

    statis.beacon_silence_rssi_a =
        le32_to_cpu(rx_info->beacon_silence_rssi_a);
    statis.beacon_silence_rssi_b =
        le32_to_cpu(rx_info->beacon_silence_rssi_b);
    statis.beacon_silence_rssi_c =
        le32_to_cpu(rx_info->beacon_silence_rssi_c);
    statis.beacon_energy_a = le32_to_cpu(rx_info->beacon_energy_a);
    statis.beacon_energy_b = le32_to_cpu(rx_info->beacon_energy_b);
    statis.beacon_energy_c = le32_to_cpu(rx_info->beacon_energy_c);

    spin_unlock_irqrestore(&il->lock, flags);

    D_CALIB("rx_enable_time = %u usecs\n", rx_enable_time);

    if (!rx_enable_time) {
        D_CALIB("<< RX Enable Time == 0!\n");
        return;
    }

    /* These stats increase monotonically, and do not reset
     *   at each beacon.  Calculate difference from last value, or just
     *   use the new stats value if it has reset or wrapped around. */
    if (data->last_bad_plcp_cnt_cck > bad_plcp_cck)
        data->last_bad_plcp_cnt_cck = bad_plcp_cck;
    else {
        bad_plcp_cck -= data->last_bad_plcp_cnt_cck;
        data->last_bad_plcp_cnt_cck += bad_plcp_cck;
    }

    if (data->last_bad_plcp_cnt_ofdm > bad_plcp_ofdm)
        data->last_bad_plcp_cnt_ofdm = bad_plcp_ofdm;
    else {
        bad_plcp_ofdm -= data->last_bad_plcp_cnt_ofdm;
        data->last_bad_plcp_cnt_ofdm += bad_plcp_ofdm;
    }

    if (data->last_fa_cnt_ofdm > fa_ofdm)
        data->last_fa_cnt_ofdm = fa_ofdm;
    else {
        fa_ofdm -= data->last_fa_cnt_ofdm;
        data->last_fa_cnt_ofdm += fa_ofdm;
    }

    if (data->last_fa_cnt_cck > fa_cck)
        data->last_fa_cnt_cck = fa_cck;
    else {
        fa_cck -= data->last_fa_cnt_cck;
        data->last_fa_cnt_cck += fa_cck;
    }

    /* Total aborted signal locks */
    norm_fa_ofdm = fa_ofdm + bad_plcp_ofdm;
    norm_fa_cck = fa_cck + bad_plcp_cck;

    D_CALIB("cck: fa %u badp %u  ofdm: fa %u badp %u\n", fa_cck,
        bad_plcp_cck, fa_ofdm, bad_plcp_ofdm);

    il4965_sens_auto_corr_ofdm(il, norm_fa_ofdm, rx_enable_time);
    il4965_sens_energy_cck(il, norm_fa_cck, rx_enable_time, &statis);

    il4965_sensitivity_write(il);
}

static inline u8
il4965_find_first_chain(u8 mask)
{
    if (mask & ANT_A)
        return CHAIN_A;
    if (mask & ANT_B)
        return CHAIN_B;
    return CHAIN_C;
}

static void
il4965_find_disconn_antenna(struct il_priv *il, u32 * average_sig,
                struct il_chain_noise_data *data)
{
    u32 active_chains = 0;
    u32 max_average_sig;
    u16 max_average_sig_antenna_i;
    u8 num_tx_chains;
    u8 first_chain;
    u16 i = 0;

    average_sig[0] =
        data->chain_signal_a /
        il->cfg->chain_noise_num_beacons;
    average_sig[1] =
        data->chain_signal_b /
        il->cfg->chain_noise_num_beacons;
    average_sig[2] =
        data->chain_signal_c /
        il->cfg->chain_noise_num_beacons;

    if (average_sig[0] >= average_sig[1]) {
        max_average_sig = average_sig[0];
        max_average_sig_antenna_i = 0;
        active_chains = (1 << max_average_sig_antenna_i);
    } else {
        max_average_sig = average_sig[1];
        max_average_sig_antenna_i = 1;
        active_chains = (1 << max_average_sig_antenna_i);
    }

    if (average_sig[2] >= max_average_sig) {
        max_average_sig = average_sig[2];
        max_average_sig_antenna_i = 2;
        active_chains = (1 << max_average_sig_antenna_i);
    }

    D_CALIB("average_sig: a %d b %d c %d\n", average_sig[0], average_sig[1],
        average_sig[2]);
    D_CALIB("max_average_sig = %d, antenna %d\n", max_average_sig,
        max_average_sig_antenna_i);

    /* Compare signal strengths for all 3 receivers. */
    for (i = 0; i < NUM_RX_CHAINS; i++) {
        if (i != max_average_sig_antenna_i) {
            s32 rssi_delta = (max_average_sig - average_sig[i]);

            /* If signal is very weak, compared with
             * strongest, mark it as disconnected. */
            if (rssi_delta > MAXIMUM_ALLOWED_PATHLOSS)
                data->disconn_array[i] = 1;
            else
                active_chains |= (1 << i);
            D_CALIB("i = %d  rssiDelta = %d  "
                "disconn_array[i] = %d\n", i, rssi_delta,
                data->disconn_array[i]);
        }
    }

    /*
     * The above algorithm sometimes fails when the ucode
     * reports 0 for all chains. It's not clear why that
     * happens to start with, but it is then causing trouble
     * because this can make us enable more chains than the
     * hardware really has.
     *
     * To be safe, simply mask out any chains that we know
     * are not on the device.
     */
    active_chains &= il->hw_params.valid_rx_ant;

    num_tx_chains = 0;
    for (i = 0; i < NUM_RX_CHAINS; i++) {
        /* loops on all the bits of
         * il->hw_setting.valid_tx_ant */
        u8 ant_msk = (1 << i);
        if (!(il->hw_params.valid_tx_ant & ant_msk))
            continue;

        num_tx_chains++;
        if (data->disconn_array[i] == 0)
            /* there is a Tx antenna connected */
            break;
        if (num_tx_chains == il->hw_params.tx_chains_num &&
            data->disconn_array[i]) {
            /*
             * If all chains are disconnected
             * connect the first valid tx chain
             */
            first_chain =
                il4965_find_first_chain(il->cfg->valid_tx_ant);
            data->disconn_array[first_chain] = 0;
            active_chains |= BIT(first_chain);
            D_CALIB("All Tx chains are disconnected"
                "- declare %d as connected\n", first_chain);
            break;
        }
    }

    if (active_chains != il->hw_params.valid_rx_ant &&
        active_chains != il->chain_noise_data.active_chains)
        D_CALIB("Detected that not all antennas are connected! "
            "Connected: %#x, valid: %#x.\n", active_chains,
            il->hw_params.valid_rx_ant);

    /* Save for use within RXON, TX, SCAN commands, etc. */
    data->active_chains = active_chains;
    D_CALIB("active_chains (bitwise) = 0x%x\n", active_chains);
}

static void
il4965_gain_computation(struct il_priv *il, u32 * average_noise,
            u16 min_average_noise_antenna_i, u32 min_average_noise,
            u8 default_chain)
{
    int i, ret;
    struct il_chain_noise_data *data = &il->chain_noise_data;

    data->delta_gain_code[min_average_noise_antenna_i] = 0;

    for (i = default_chain; i < NUM_RX_CHAINS; i++) {
        s32 delta_g = 0;

        if (!data->disconn_array[i] &&
            data->delta_gain_code[i] ==
            CHAIN_NOISE_DELTA_GAIN_INIT_VAL) {
            delta_g = average_noise[i] - min_average_noise;
            data->delta_gain_code[i] = (u8) ((delta_g * 10) / 15);
            data->delta_gain_code[i] =
                min(data->delta_gain_code[i],
                (u8) CHAIN_NOISE_MAX_DELTA_GAIN_CODE);

            data->delta_gain_code[i] =
                (data->delta_gain_code[i] | (1 << 2));
        } else {
            data->delta_gain_code[i] = 0;
        }
    }
    D_CALIB("delta_gain_codes: a %d b %d c %d\n", data->delta_gain_code[0],
        data->delta_gain_code[1], data->delta_gain_code[2]);

    /* Differential gain gets sent to uCode only once */
    if (!data->radio_write) {
        struct il_calib_diff_gain_cmd cmd;
        data->radio_write = 1;

        memset(&cmd, 0, sizeof(cmd));
        cmd.hdr.op_code = IL_PHY_CALIBRATE_DIFF_GAIN_CMD;
        cmd.diff_gain_a = data->delta_gain_code[0];
        cmd.diff_gain_b = data->delta_gain_code[1];
        cmd.diff_gain_c = data->delta_gain_code[2];
        ret = il_send_cmd_pdu(il, C_PHY_CALIBRATION, sizeof(cmd), &cmd);
        if (ret)
            D_CALIB("fail sending cmd " "C_PHY_CALIBRATION\n");

        /* TODO we might want recalculate
         * rx_chain in rxon cmd */

        /* Mark so we run this algo only once! */
        data->state = IL_CHAIN_NOISE_CALIBRATED;
    }
}

/*
 * Accumulate 16 beacons of signal and noise stats for each of
 *   3 receivers/antennas/rx-chains, then figure out:
 * 1)  Which antennas are connected.
 * 2)  Differential rx gain settings to balance the 3 receivers.
 */
void
il4965_chain_noise_calibration(struct il_priv *il, void *stat_resp)
{
    struct il_chain_noise_data *data = NULL;

    u32 chain_noise_a;
    u32 chain_noise_b;
    u32 chain_noise_c;
    u32 chain_sig_a;
    u32 chain_sig_b;
    u32 chain_sig_c;
    u32 average_sig[NUM_RX_CHAINS] = { INITIALIZATION_VALUE };
    u32 average_noise[NUM_RX_CHAINS] = { INITIALIZATION_VALUE };
    u32 min_average_noise = MIN_AVERAGE_NOISE_MAX_VALUE;
    u16 min_average_noise_antenna_i = INITIALIZATION_VALUE;
    u16 i = 0;
    u16 rxon_chnum = INITIALIZATION_VALUE;
    u16 stat_chnum = INITIALIZATION_VALUE;
    u8 rxon_band24;
    u8 stat_band24;
    unsigned long flags;
    struct stats_rx_non_phy *rx_info;

    if (il->disable_chain_noise_cal)
        return;

    data = &(il->chain_noise_data);

    /*
     * Accumulate just the first "chain_noise_num_beacons" after
     * the first association, then we're done forever.
     */
    if (data->state != IL_CHAIN_NOISE_ACCUMULATE) {
        if (data->state == IL_CHAIN_NOISE_ALIVE)
            D_CALIB("Wait for noise calib reset\n");
        return;
    }

    spin_lock_irqsave(&il->lock, flags);

    rx_info = &(((struct il_notif_stats *)stat_resp)->rx.general);

    if (rx_info->interference_data_flag != INTERFERENCE_DATA_AVAILABLE) {
        D_CALIB(" << Interference data unavailable\n");
        spin_unlock_irqrestore(&il->lock, flags);
        return;
    }

    rxon_band24 = !!(il->staging.flags & RXON_FLG_BAND_24G_MSK);
    rxon_chnum = le16_to_cpu(il->staging.channel);

    stat_band24 =
        !!(((struct il_notif_stats *)stat_resp)->
           flag & STATS_REPLY_FLG_BAND_24G_MSK);
    stat_chnum =
        le32_to_cpu(((struct il_notif_stats *)stat_resp)->flag) >> 16;

    /* Make sure we accumulate data for just the associated channel
     *   (even if scanning). */
    if (rxon_chnum != stat_chnum || rxon_band24 != stat_band24) {
        D_CALIB("Stats not from chan=%d, band24=%d\n", rxon_chnum,
            rxon_band24);
        spin_unlock_irqrestore(&il->lock, flags);
        return;
    }

    /*
     *  Accumulate beacon stats values across
     * "chain_noise_num_beacons"
     */
    chain_noise_a =
        le32_to_cpu(rx_info->beacon_silence_rssi_a) & IN_BAND_FILTER;
    chain_noise_b =
        le32_to_cpu(rx_info->beacon_silence_rssi_b) & IN_BAND_FILTER;
    chain_noise_c =
        le32_to_cpu(rx_info->beacon_silence_rssi_c) & IN_BAND_FILTER;

    chain_sig_a = le32_to_cpu(rx_info->beacon_rssi_a) & IN_BAND_FILTER;
    chain_sig_b = le32_to_cpu(rx_info->beacon_rssi_b) & IN_BAND_FILTER;
    chain_sig_c = le32_to_cpu(rx_info->beacon_rssi_c) & IN_BAND_FILTER;

    spin_unlock_irqrestore(&il->lock, flags);

    data->beacon_count++;

    data->chain_noise_a = (chain_noise_a + data->chain_noise_a);
    data->chain_noise_b = (chain_noise_b + data->chain_noise_b);
    data->chain_noise_c = (chain_noise_c + data->chain_noise_c);

    data->chain_signal_a = (chain_sig_a + data->chain_signal_a);
    data->chain_signal_b = (chain_sig_b + data->chain_signal_b);
    data->chain_signal_c = (chain_sig_c + data->chain_signal_c);

    D_CALIB("chan=%d, band24=%d, beacon=%d\n", rxon_chnum, rxon_band24,
        data->beacon_count);
    D_CALIB("chain_sig: a %d b %d c %d\n", chain_sig_a, chain_sig_b,
        chain_sig_c);
    D_CALIB("chain_noise: a %d b %d c %d\n", chain_noise_a, chain_noise_b,
        chain_noise_c);

    /* If this is the "chain_noise_num_beacons", determine:
     * 1)  Disconnected antennas (using signal strengths)
     * 2)  Differential gain (using silence noise) to balance receivers */
    if (data->beacon_count != il->cfg->chain_noise_num_beacons)
        return;

    /* Analyze signal for disconnected antenna */
    il4965_find_disconn_antenna(il, average_sig, data);

    /* Analyze noise for rx balance */
    average_noise[0] =
        data->chain_noise_a / il->cfg->chain_noise_num_beacons;
    average_noise[1] =
        data->chain_noise_b / il->cfg->chain_noise_num_beacons;
    average_noise[2] =
        data->chain_noise_c / il->cfg->chain_noise_num_beacons;

    for (i = 0; i < NUM_RX_CHAINS; i++) {
        if (!data->disconn_array[i] &&
            average_noise[i] <= min_average_noise) {
            /* This means that chain i is active and has
             * lower noise values so far: */
            min_average_noise = average_noise[i];
            min_average_noise_antenna_i = i;
        }
    }

    D_CALIB("average_noise: a %d b %d c %d\n", average_noise[0],
        average_noise[1], average_noise[2]);

    D_CALIB("min_average_noise = %d, antenna %d\n", min_average_noise,
        min_average_noise_antenna_i);

    il4965_gain_computation(il, average_noise, min_average_noise_antenna_i,
                min_average_noise,
                il4965_find_first_chain(il->cfg->valid_rx_ant));

    /* Some power changes may have been made during the calibration.
     * Update and commit the RXON
     */
    if (il->ops->update_chain_flags)
        il->ops->update_chain_flags(il);

    data->state = IL_CHAIN_NOISE_DONE;
    il_power_update_mode(il, false);
}

void
il4965_reset_run_time_calib(struct il_priv *il)
{
    int i;
    memset(&(il->sensitivity_data), 0, sizeof(struct il_sensitivity_data));
    memset(&(il->chain_noise_data), 0, sizeof(struct il_chain_noise_data));
    for (i = 0; i < NUM_RX_CHAINS; i++)
        il->chain_noise_data.delta_gain_code[i] =
            CHAIN_NOISE_DELTA_GAIN_INIT_VAL;

    /* Ask for stats now, the uCode will send notification
     * periodically after association */
    il_send_stats_request(il, CMD_ASYNC, true);
}