/*
 * Copyright (c) 2012 Qualcomm Atheros, Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "ath9k.h"

/*
 * AR9285
 * ======
 *
 * EEPROM has 2 4-bit fields containing the card configuration.
 *
 * antdiv_ctl1:
 * ------------
 * bb_enable_ant_div_lnadiv : 1
 * bb_ant_div_alt_gaintb    : 1
 * bb_ant_div_main_gaintb   : 1
 * bb_enable_ant_fast_div   : 1
 *
 * antdiv_ctl2:
 * -----------
 * bb_ant_div_alt_lnaconf  : 2
 * bb_ant_div_main_lnaconf : 2
 *
 * The EEPROM bits are used as follows:
 * ------------------------------------
 *
 * bb_enable_ant_div_lnadiv      - Enable LNA path rx antenna diversity/combining.
 *                                 Set in AR_PHY_MULTICHAIN_GAIN_CTL.
 *
 * bb_ant_div_[alt/main]_gaintb  - 0 -> Antenna config Alt/Main uses gaintable 0
 *                                 1 -> Antenna config Alt/Main uses gaintable 1
 *                                 Set in AR_PHY_MULTICHAIN_GAIN_CTL.
 *
 * bb_enable_ant_fast_div        - Enable fast antenna diversity.
 *                                 Set in AR_PHY_CCK_DETECT.
 *
 * bb_ant_div_[alt/main]_lnaconf - Alt/Main LNA diversity/combining input config.
 *                                 Set in AR_PHY_MULTICHAIN_GAIN_CTL.
 *                                 10=LNA1
 *                                 01=LNA2
 *                                 11=LNA1+LNA2
 *                                 00=LNA1-LNA2
 *
 * AR9485 / AR9565 / AR9331
 * ========================
 *
 * The same bits are present in the EEPROM, but the location in the
 * EEPROM is different (ant_div_control in ar9300_BaseExtension_1).
 *
 * ant_div_alt_lnaconf      ==> bit 0~1
 * ant_div_main_lnaconf     ==> bit 2~3
 * ant_div_alt_gaintb       ==> bit 4
 * ant_div_main_gaintb      ==> bit 5
 * enable_ant_div_lnadiv    ==> bit 6
 * enable_ant_fast_div      ==> bit 7
 */

static inline bool ath_is_alt_ant_ratio_better(struct ath_ant_comb *antcomb,
                                               int alt_ratio, int maxdelta,
                                               int mindelta, int main_rssi_avg,
                                               int alt_rssi_avg, int pkt_count)
{
        if (pkt_count <= 50)
                return false;

        if (alt_rssi_avg > main_rssi_avg + mindelta)
                return true;

        if (alt_ratio >= antcomb->ant_ratio2 &&
            alt_rssi_avg >= antcomb->low_rssi_thresh &&
            (alt_rssi_avg > main_rssi_avg + maxdelta))
                return true;

        return false;
}

static inline bool ath_ant_div_comb_alt_check(struct ath_hw_antcomb_conf *conf,
                                              struct ath_ant_comb *antcomb,
                                              int alt_ratio, int alt_rssi_avg,
                                              int main_rssi_avg)
{
        bool result, set1, set2;

        result = set1 = set2 = false;

        if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA2 &&
            conf->alt_lna_conf == ATH_ANT_DIV_COMB_LNA1)
                set1 = true;

        if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA1 &&
            conf->alt_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                set2 = true;

        switch (conf->div_group) {
        case 0:
                if (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO)
                        result = true;
                break;
        case 1:
        case 2:
                if (alt_rssi_avg < 4 || alt_rssi_avg < antcomb->low_rssi_thresh)
                        break;

                if ((set1 && (alt_rssi_avg >= (main_rssi_avg - 5))) ||
                    (set2 && (alt_rssi_avg >= (main_rssi_avg - 2))) ||
                    (alt_ratio > antcomb->ant_ratio))
                        result = true;

                break;
        case 3:
                if (alt_rssi_avg < 4 || alt_rssi_avg < antcomb->low_rssi_thresh)
                        break;

                if ((set1 && (alt_rssi_avg >= (main_rssi_avg - 3))) ||
                    (set2 && (alt_rssi_avg >= (main_rssi_avg + 3))) ||
                    (alt_ratio > antcomb->ant_ratio))
                        result = true;

                break;
        }

        return result;
}

static void ath_lnaconf_alt_good_scan(struct ath_ant_comb *antcomb,
                                      struct ath_hw_antcomb_conf ant_conf,
                                      int main_rssi_avg)
{
        antcomb->quick_scan_cnt = 0;

        if (ant_conf.main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                antcomb->rssi_lna2 = main_rssi_avg;
        else if (ant_conf.main_lna_conf == ATH_ANT_DIV_COMB_LNA1)
                antcomb->rssi_lna1 = main_rssi_avg;

        switch ((ant_conf.main_lna_conf << 4) | ant_conf.alt_lna_conf) {
        case 0x10: /* LNA2 A-B */
                antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                antcomb->first_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA1;
                break;
        case 0x20: /* LNA1 A-B */
                antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                antcomb->first_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA2;
                break;
        case 0x21: /* LNA1 LNA2 */
                antcomb->main_conf = ATH_ANT_DIV_COMB_LNA2;
                antcomb->first_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                antcomb->second_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                break;
        case 0x12: /* LNA2 LNA1 */
                antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1;
                antcomb->first_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                antcomb->second_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                break;
        case 0x13: /* LNA2 A+B */
                antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                antcomb->first_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA1;
                break;
        case 0x23: /* LNA1 A+B */
                antcomb->main_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                antcomb->first_quick_scan_conf =
                        ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                antcomb->second_quick_scan_conf = ATH_ANT_DIV_COMB_LNA2;
                break;
        default:
                break;
        }
}

static void ath_ant_set_alt_ratio(struct ath_ant_comb *antcomb,
                                  struct ath_hw_antcomb_conf *conf)
{
        /* set alt to the conf with maximum ratio */
        if (antcomb->first_ratio && antcomb->second_ratio) {
                if (antcomb->rssi_second > antcomb->rssi_third) {
                        /* first alt*/
                        if ((antcomb->first_quick_scan_conf == ATH_ANT_DIV_COMB_LNA1) ||
                            (antcomb->first_quick_scan_conf == ATH_ANT_DIV_COMB_LNA2))
                                /* Set alt LNA1 or LNA2*/
                                if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                                        conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                                else
                                        conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                        else
                                /* Set alt to A+B or A-B */
                                conf->alt_lna_conf =
                                        antcomb->first_quick_scan_conf;
                } else if ((antcomb->second_quick_scan_conf == ATH_ANT_DIV_COMB_LNA1) ||
                           (antcomb->second_quick_scan_conf == ATH_ANT_DIV_COMB_LNA2)) {
                        /* Set alt LNA1 or LNA2 */
                        if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                        else
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                } else {
                        /* Set alt to A+B or A-B */
                        conf->alt_lna_conf = antcomb->second_quick_scan_conf;
                }
        } else if (antcomb->first_ratio) {
                /* first alt */
                if ((antcomb->first_quick_scan_conf == ATH_ANT_DIV_COMB_LNA1) ||
                    (antcomb->first_quick_scan_conf == ATH_ANT_DIV_COMB_LNA2))
                        /* Set alt LNA1 or LNA2 */
                        if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                        else
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                else
                        /* Set alt to A+B or A-B */
                        conf->alt_lna_conf = antcomb->first_quick_scan_conf;
        } else if (antcomb->second_ratio) {
                /* second alt */
                if ((antcomb->second_quick_scan_conf == ATH_ANT_DIV_COMB_LNA1) ||
                    (antcomb->second_quick_scan_conf == ATH_ANT_DIV_COMB_LNA2))
                        /* Set alt LNA1 or LNA2 */
                        if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                        else
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                else
                        /* Set alt to A+B or A-B */
                        conf->alt_lna_conf = antcomb->second_quick_scan_conf;
        } else {
                /* main is largest */
                if ((antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1) ||
                    (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2))
                        /* Set alt LNA1 or LNA2 */
                        if (conf->main_lna_conf == ATH_ANT_DIV_COMB_LNA2)
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                        else
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                else
                        /* Set alt to A+B or A-B */
                        conf->alt_lna_conf = antcomb->main_conf;
        }
}

static void ath_select_ant_div_from_quick_scan(struct ath_ant_comb *antcomb,
                                       struct ath_hw_antcomb_conf *div_ant_conf,
                                       int main_rssi_avg, int alt_rssi_avg,
                                       int alt_ratio)
{
        /* alt_good */
        switch (antcomb->quick_scan_cnt) {
        case 0:
                /* set alt to main, and alt to first conf */
                div_ant_conf->main_lna_conf = antcomb->main_conf;
                div_ant_conf->alt_lna_conf = antcomb->first_quick_scan_conf;
                break;
        case 1:
                /* set alt to main, and alt to first conf */
                div_ant_conf->main_lna_conf = antcomb->main_conf;
                div_ant_conf->alt_lna_conf = antcomb->second_quick_scan_conf;
                antcomb->rssi_first = main_rssi_avg;
                antcomb->rssi_second = alt_rssi_avg;

                if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1) {
                        /* main is LNA1 */
                        if (ath_is_alt_ant_ratio_better(antcomb, alt_ratio,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_HI,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
                                                main_rssi_avg, alt_rssi_avg,
                                                antcomb->total_pkt_count))
                                antcomb->first_ratio = true;
                        else
                                antcomb->first_ratio = false;
                } else if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2) {
                        if (ath_is_alt_ant_ratio_better(antcomb, alt_ratio,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_MID,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
                                                main_rssi_avg, alt_rssi_avg,
                                                antcomb->total_pkt_count))
                                antcomb->first_ratio = true;
                        else
                                antcomb->first_ratio = false;
                } else {
                        if (ath_is_alt_ant_ratio_better(antcomb, alt_ratio,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_HI,
                                                0,
                                                main_rssi_avg, alt_rssi_avg,
                                                antcomb->total_pkt_count))
                                antcomb->first_ratio = true;
                        else
                                antcomb->first_ratio = false;
                }
                break;
        case 2:
                antcomb->alt_good = false;
                antcomb->scan_not_start = false;
                antcomb->scan = false;
                antcomb->rssi_first = main_rssi_avg;
                antcomb->rssi_third = alt_rssi_avg;

                switch(antcomb->second_quick_scan_conf) {
                case ATH_ANT_DIV_COMB_LNA1:
                        antcomb->rssi_lna1 = alt_rssi_avg;
                        break;
                case ATH_ANT_DIV_COMB_LNA2:
                        antcomb->rssi_lna2 = alt_rssi_avg;
                        break;
                case ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2:
                        if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2)
                                antcomb->rssi_lna2 = main_rssi_avg;
                        else if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1)
                                antcomb->rssi_lna1 = main_rssi_avg;
                        break;
                default:
                        break;
                }

                if (antcomb->rssi_lna2 > antcomb->rssi_lna1 +
                    div_ant_conf->lna1_lna2_switch_delta)
                        div_ant_conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                else
                        div_ant_conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;

                if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA1) {
                        if (ath_is_alt_ant_ratio_better(antcomb, alt_ratio,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_HI,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
                                                main_rssi_avg, alt_rssi_avg,
                                                antcomb->total_pkt_count))
                                antcomb->second_ratio = true;
                        else
                                antcomb->second_ratio = false;
                } else if (antcomb->main_conf == ATH_ANT_DIV_COMB_LNA2) {
                        if (ath_is_alt_ant_ratio_better(antcomb, alt_ratio,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_MID,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_LOW,
                                                main_rssi_avg, alt_rssi_avg,
                                                antcomb->total_pkt_count))
                                antcomb->second_ratio = true;
                        else
                                antcomb->second_ratio = false;
                } else {
                        if (ath_is_alt_ant_ratio_better(antcomb, alt_ratio,
                                                ATH_ANT_DIV_COMB_LNA1_DELTA_HI,
                                                0,
                                                main_rssi_avg, alt_rssi_avg,
                                                antcomb->total_pkt_count))
                                antcomb->second_ratio = true;
                        else
                                antcomb->second_ratio = false;
                }

                ath_ant_set_alt_ratio(antcomb, div_ant_conf);

                break;
        default:
                break;
        }
}

static void ath_ant_div_conf_fast_divbias(struct ath_hw_antcomb_conf *ant_conf,
                                          struct ath_ant_comb *antcomb,
                                          int alt_ratio)
{
        ant_conf->main_gaintb = 0;
        ant_conf->alt_gaintb = 0;

        if (ant_conf->div_group == 0) {
                /* Adjust the fast_div_bias based on main and alt lna conf */
                switch ((ant_conf->main_lna_conf << 4) |
                                ant_conf->alt_lna_conf) {
                case 0x01: /* A-B LNA2 */
                        ant_conf->fast_div_bias = 0x3b;
                        break;
                case 0x02: /* A-B LNA1 */
                        ant_conf->fast_div_bias = 0x3d;
                        break;
                case 0x03: /* A-B A+B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x10: /* LNA2 A-B */
                        ant_conf->fast_div_bias = 0x7;
                        break;
                case 0x12: /* LNA2 LNA1 */
                        ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x13: /* LNA2 A+B */
                        ant_conf->fast_div_bias = 0x7;
                        break;
                case 0x20: /* LNA1 A-B */
                        ant_conf->fast_div_bias = 0x6;
                        break;
                case 0x21: /* LNA1 LNA2 */
                        ant_conf->fast_div_bias = 0x0;
                        break;
                case 0x23: /* LNA1 A+B */
                        ant_conf->fast_div_bias = 0x6;
                        break;
                case 0x30: /* A+B A-B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x31: /* A+B LNA2 */
                        ant_conf->fast_div_bias = 0x3b;
                        break;
                case 0x32: /* A+B LNA1 */
                        ant_conf->fast_div_bias = 0x3d;
                        break;
                default:
                        break;
                }
        } else if (ant_conf->div_group == 1) {
                /* Adjust the fast_div_bias based on main and alt_lna_conf */
                switch ((ant_conf->main_lna_conf << 4) |
                        ant_conf->alt_lna_conf) {
                case 0x01: /* A-B LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x02: /* A-B LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x03: /* A-B A+B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x10: /* LNA2 A-B */
                        if (!(antcomb->scan) &&
                            (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO))
                                ant_conf->fast_div_bias = 0x3f;
                        else
                                ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x12: /* LNA2 LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x13: /* LNA2 A+B */
                        if (!(antcomb->scan) &&
                            (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO))
                                ant_conf->fast_div_bias = 0x3f;
                        else
                                ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x20: /* LNA1 A-B */
                        if (!(antcomb->scan) &&
                            (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO))
                                ant_conf->fast_div_bias = 0x3f;
                        else
                                ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x21: /* LNA1 LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x23: /* LNA1 A+B */
                        if (!(antcomb->scan) &&
                            (alt_ratio > ATH_ANT_DIV_COMB_ALT_ANT_RATIO))
                                ant_conf->fast_div_bias = 0x3f;
                        else
                                ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x30: /* A+B A-B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x31: /* A+B LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x32: /* A+B LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                default:
                        break;
                }
        } else if (ant_conf->div_group == 2) {
                /* Adjust the fast_div_bias based on main and alt_lna_conf */
                switch ((ant_conf->main_lna_conf << 4) |
                                ant_conf->alt_lna_conf) {
                case 0x01: /* A-B LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x02: /* A-B LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x03: /* A-B A+B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x10: /* LNA2 A-B */
                        if (!antcomb->scan && (alt_ratio > antcomb->ant_ratio))
                                ant_conf->fast_div_bias = 0x1;
                        else
                                ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x12: /* LNA2 LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x13: /* LNA2 A+B */
                        if (!antcomb->scan && (alt_ratio > antcomb->ant_ratio))
                                ant_conf->fast_div_bias = 0x1;
                        else
                                ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x20: /* LNA1 A-B */
                        if (!antcomb->scan && (alt_ratio > antcomb->ant_ratio))
                                ant_conf->fast_div_bias = 0x1;
                        else
                                ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x21: /* LNA1 LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x23: /* LNA1 A+B */
                        if (!antcomb->scan && (alt_ratio > antcomb->ant_ratio))
                                ant_conf->fast_div_bias = 0x1;
                        else
                                ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x30: /* A+B A-B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x31: /* A+B LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x32: /* A+B LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                default:
                        break;
                }

                if (antcomb->fast_div_bias)
                        ant_conf->fast_div_bias = antcomb->fast_div_bias;
        } else if (ant_conf->div_group == 3) {
                switch ((ant_conf->main_lna_conf << 4) |
                        ant_conf->alt_lna_conf) {
                case 0x01: /* A-B LNA2 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x02: /* A-B LNA1 */
                        ant_conf->fast_div_bias = 0x39;
                        break;
                case 0x03: /* A-B A+B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x10: /* LNA2 A-B */
                        ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x12: /* LNA2 LNA1 */
                        ant_conf->fast_div_bias = 0x3f;
                        break;
                case 0x13: /* LNA2 A+B */
                        ant_conf->fast_div_bias = 0x2;
                        break;
                case 0x20: /* LNA1 A-B */
                        ant_conf->fast_div_bias = 0x3;
                        break;
                case 0x21: /* LNA1 LNA2 */
                        ant_conf->fast_div_bias = 0x3;
                        break;
                case 0x23: /* LNA1 A+B */
                        ant_conf->fast_div_bias = 0x3;
                        break;
                case 0x30: /* A+B A-B */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                case 0x31: /* A+B LNA2 */
                        ant_conf->fast_div_bias = 0x6;
                        break;
                case 0x32: /* A+B LNA1 */
                        ant_conf->fast_div_bias = 0x1;
                        break;
                default:
                        break;
                }
        }
}

static void ath_ant_try_scan(struct ath_ant_comb *antcomb,
                             struct ath_hw_antcomb_conf *conf,
                             int curr_alt_set, int alt_rssi_avg,
                             int main_rssi_avg)
{
        switch (curr_alt_set) {
        case ATH_ANT_DIV_COMB_LNA2:
                antcomb->rssi_lna2 = alt_rssi_avg;
                antcomb->rssi_lna1 = main_rssi_avg;
                antcomb->scan = true;
                /* set to A+B */
                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                break;
        case ATH_ANT_DIV_COMB_LNA1:
                antcomb->rssi_lna1 = alt_rssi_avg;
                antcomb->rssi_lna2 = main_rssi_avg;
                antcomb->scan = true;
                /* set to A+B */
                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                break;
        case ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2:
                antcomb->rssi_add = alt_rssi_avg;
                antcomb->scan = true;
                /* set to A-B */
                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                break;
        case ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2:
                antcomb->rssi_sub = alt_rssi_avg;
                antcomb->scan = false;
                if (antcomb->rssi_lna2 >
                    (antcomb->rssi_lna1 + conf->lna1_lna2_switch_delta)) {
                        /* use LNA2 as main LNA */
                        if ((antcomb->rssi_add > antcomb->rssi_lna1) &&
                            (antcomb->rssi_add > antcomb->rssi_sub)) {
                                /* set to A+B */
                                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                        } else if (antcomb->rssi_sub >
                                   antcomb->rssi_lna1) {
                                /* set to A-B */
                                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                        } else {
                                /* set to LNA1 */
                                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                        }
                } else {
                        /* use LNA1 as main LNA */
                        if ((antcomb->rssi_add > antcomb->rssi_lna2) &&
                            (antcomb->rssi_add > antcomb->rssi_sub)) {
                                /* set to A+B */
                                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_PLUS_LNA2;
                        } else if (antcomb->rssi_sub >
                                   antcomb->rssi_lna2) {
                                /* set to A-B */
                                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1_MINUS_LNA2;
                        } else {
                                /* set to LNA2 */
                                conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                                conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                        }
                }
                break;
        default:
                break;
        }
}

static bool ath_ant_try_switch(struct ath_hw_antcomb_conf *div_ant_conf,
                               struct ath_ant_comb *antcomb,
                               int alt_ratio, int alt_rssi_avg,
                               int main_rssi_avg, int curr_main_set,
                               int curr_alt_set)
{
        bool ret = false;

        if (ath_ant_div_comb_alt_check(div_ant_conf, antcomb, alt_ratio,
                                       alt_rssi_avg, main_rssi_avg)) {
                if (curr_alt_set == ATH_ANT_DIV_COMB_LNA2) {
                        /*
                         * Switch main and alt LNA.
                         */
                        div_ant_conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                        div_ant_conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                } else if (curr_alt_set == ATH_ANT_DIV_COMB_LNA1) {
                        div_ant_conf->main_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                        div_ant_conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;
                }

                ret = true;
        } else if ((curr_alt_set != ATH_ANT_DIV_COMB_LNA1) &&
                   (curr_alt_set != ATH_ANT_DIV_COMB_LNA2)) {
                /*
                  Set alt to another LNA.
                */
                if (curr_main_set == ATH_ANT_DIV_COMB_LNA2)
                        div_ant_conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA1;
                else if (curr_main_set == ATH_ANT_DIV_COMB_LNA1)
                        div_ant_conf->alt_lna_conf = ATH_ANT_DIV_COMB_LNA2;

                ret = true;
        }

        return ret;
}

static bool ath_ant_short_scan_check(struct ath_ant_comb *antcomb)
{
        int alt_ratio;

        if (!antcomb->scan || !antcomb->alt_good)
                return false;

        if (time_after(jiffies, antcomb->scan_start_time +
                       msecs_to_jiffies(ATH_ANT_DIV_COMB_SHORT_SCAN_INTR)))
                return true;

        if (antcomb->total_pkt_count == ATH_ANT_DIV_COMB_SHORT_SCAN_PKTCOUNT) {
                alt_ratio = ((antcomb->alt_recv_cnt * 100) /
                             antcomb->total_pkt_count);
                if (alt_ratio < antcomb->ant_ratio)
                        return true;
        }

        return false;
}

void ath_ant_comb_scan(struct ath_softc *sc, struct ath_rx_status *rs)
{
        struct ath_hw_antcomb_conf div_ant_conf;
        struct ath_ant_comb *antcomb = &sc->ant_comb;
        int alt_ratio = 0, alt_rssi_avg = 0, main_rssi_avg = 0, curr_alt_set;
        int curr_main_set;
        int main_rssi = rs->rs_rssi_ctl[0];
        int alt_rssi = rs->rs_rssi_ctl[1];
        int rx_ant_conf,  main_ant_conf;
        bool short_scan = false, ret;

        rx_ant_conf = (rs->rs_rssi_ctl[2] >> ATH_ANT_RX_CURRENT_SHIFT) &
                       ATH_ANT_RX_MASK;
        main_ant_conf = (rs->rs_rssi_ctl[2] >> ATH_ANT_RX_MAIN_SHIFT) &
                         ATH_ANT_RX_MASK;

        if (alt_rssi >= antcomb->low_rssi_thresh) {
                antcomb->ant_ratio = ATH_ANT_DIV_COMB_ALT_ANT_RATIO;
                antcomb->ant_ratio2 = ATH_ANT_DIV_COMB_ALT_ANT_RATIO2;
        } else {
                antcomb->ant_ratio = ATH_ANT_DIV_COMB_ALT_ANT_RATIO_LOW_RSSI;
                antcomb->ant_ratio2 = ATH_ANT_DIV_COMB_ALT_ANT_RATIO2_LOW_RSSI;
        }

        /* Record packet only when both main_rssi and  alt_rssi is positive */
        if (main_rssi > 0 && alt_rssi > 0) {
                antcomb->total_pkt_count++;
                antcomb->main_total_rssi += main_rssi;
                antcomb->alt_total_rssi  += alt_rssi;

                if (main_ant_conf == rx_ant_conf)
                        antcomb->main_recv_cnt++;
                else
                        antcomb->alt_recv_cnt++;
        }

        if (main_ant_conf == rx_ant_conf) {
                ANT_STAT_INC(sc, ANT_MAIN, recv_cnt);
                ANT_LNA_INC(sc, ANT_MAIN, rx_ant_conf);
        } else {
                ANT_STAT_INC(sc, ANT_ALT, recv_cnt);
                ANT_LNA_INC(sc, ANT_ALT, rx_ant_conf);
        }

        /* Short scan check */
        short_scan = ath_ant_short_scan_check(antcomb);

        if (((antcomb->total_pkt_count < ATH_ANT_DIV_COMB_MAX_PKTCOUNT) ||
             rs->rs_moreaggr) && !short_scan)
                return;

        if (antcomb->total_pkt_count) {
                alt_ratio = ((antcomb->alt_recv_cnt * 100) /
                             antcomb->total_pkt_count);
                main_rssi_avg = (antcomb->main_total_rssi /
                                 antcomb->total_pkt_count);
                alt_rssi_avg = (antcomb->alt_total_rssi /
                                 antcomb->total_pkt_count);
        }

        ath9k_hw_antdiv_comb_conf_get(sc->sc_ah, &div_ant_conf);
        curr_alt_set = div_ant_conf.alt_lna_conf;
        curr_main_set = div_ant_conf.main_lna_conf;
        antcomb->count++;

        if (antcomb->count == ATH_ANT_DIV_COMB_MAX_COUNT) {
                if (alt_ratio > antcomb->ant_ratio) {
                        ath_lnaconf_alt_good_scan(antcomb, div_ant_conf,
                                                  main_rssi_avg);
                        antcomb->alt_good = true;
                } else {
                        antcomb->alt_good = false;
                }

                antcomb->count = 0;
                antcomb->scan = true;
                antcomb->scan_not_start = true;
        }

        if (!antcomb->scan) {
                ret = ath_ant_try_switch(&div_ant_conf, antcomb, alt_ratio,
                                         alt_rssi_avg, main_rssi_avg,
                                         curr_main_set, curr_alt_set);
                if (ret)
                        goto div_comb_done;
        }

        if (!antcomb->scan &&
            (alt_rssi_avg < (main_rssi_avg + div_ant_conf.lna1_lna2_delta)))
                goto div_comb_done;

        if (!antcomb->scan_not_start) {
                ath_ant_try_scan(antcomb, &div_ant_conf, curr_alt_set,
                                 alt_rssi_avg, main_rssi_avg);
        } else {
                if (!antcomb->alt_good) {
                        antcomb->scan_not_start = false;
                        /* Set alt to another LNA */
                        if (curr_main_set == ATH_ANT_DIV_COMB_LNA2) {
                                div_ant_conf.main_lna_conf =
                                        ATH_ANT_DIV_COMB_LNA2;
                                div_ant_conf.alt_lna_conf =
                                        ATH_ANT_DIV_COMB_LNA1;
                        } else if (curr_main_set == ATH_ANT_DIV_COMB_LNA1) {
                                div_ant_conf.main_lna_conf =
                                        ATH_ANT_DIV_COMB_LNA1;
                                div_ant_conf.alt_lna_conf =
                                        ATH_ANT_DIV_COMB_LNA2;
                        }
                        goto div_comb_done;
                }
                ath_select_ant_div_from_quick_scan(antcomb, &div_ant_conf,
                                                   main_rssi_avg, alt_rssi_avg,
                                                   alt_ratio);
                antcomb->quick_scan_cnt++;
        }

div_comb_done:
        ath_ant_div_conf_fast_divbias(&div_ant_conf, antcomb, alt_ratio);
        ath9k_hw_antdiv_comb_conf_set(sc->sc_ah, &div_ant_conf);
        ath9k_debug_stat_ant(sc, &div_ant_conf, main_rssi_avg, alt_rssi_avg);

        antcomb->scan_start_time = jiffies;
        antcomb->total_pkt_count = 0;
        antcomb->main_total_rssi = 0;
        antcomb->alt_total_rssi = 0;
        antcomb->main_recv_cnt = 0;
        antcomb->alt_recv_cnt = 0;
}