/*
 * Copyright (c) 2008-2011 Atheros Communications 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 <linux/export.h>
#include "common.h"

#define FUDGE 2

static u32 ath9k_get_next_tbtt(struct ath_hw *ah, u64 tsf,
                               unsigned int interval)
{
        unsigned int offset, divisor;

        tsf += TU_TO_USEC(FUDGE + ah->config.sw_beacon_response_time);
        divisor = TU_TO_USEC(interval);
        div_u64_rem(tsf, divisor, &offset);

        return (u32) tsf + divisor - offset;
}

/*
 * This sets up the beacon timers according to the timestamp of the last
 * received beacon and the current TSF, configures PCF and DTIM
 * handling, programs the sleep registers so the hardware will wakeup in
 * time to receive beacons, and configures the beacon miss handling so
 * we'll receive a BMISS interrupt when we stop seeing beacons from the AP
 * we've associated with.
 */
int ath9k_cmn_beacon_config_sta(struct ath_hw *ah,
                                 struct ath_beacon_config *conf,
                                 struct ath9k_beacon_state *bs)
{
        struct ath_common *common = ath9k_hw_common(ah);
        int dtim_intval;
        u64 tsf;

        /* No need to configure beacon if we are not associated */
        if (!test_bit(ATH_OP_PRIM_STA_VIF, &common->op_flags)) {
                ath_dbg(common, BEACON,
                        "STA is not yet associated..skipping beacon config\n");
                return -EPERM;
        }

        memset(bs, 0, sizeof(*bs));
        conf->intval = conf->beacon_interval;

        /*
         * Setup dtim parameters according to
         * last beacon we received (which may be none).
         */
        dtim_intval = conf->intval * conf->dtim_period;

        /*
         * Pull nexttbtt forward to reflect the current
         * TSF and calculate dtim state for the result.
         */
        tsf = ath9k_hw_gettsf64(ah);
        conf->nexttbtt = ath9k_get_next_tbtt(ah, tsf, conf->intval);

        bs->bs_intval = TU_TO_USEC(conf->intval);
        bs->bs_dtimperiod = conf->dtim_period * bs->bs_intval;
        bs->bs_nexttbtt = conf->nexttbtt;
        bs->bs_nextdtim = conf->nexttbtt;
        if (conf->dtim_period > 1)
                bs->bs_nextdtim = ath9k_get_next_tbtt(ah, tsf, dtim_intval);

        /*
         * Calculate the number of consecutive beacons to miss* before taking
         * a BMISS interrupt. The configuration is specified in TU so we only
         * need calculate based on the beacon interval.  Note that we clamp the
         * result to at most 15 beacons.
         */
        bs->bs_bmissthreshold = DIV_ROUND_UP(conf->bmiss_timeout, conf->intval);
        if (bs->bs_bmissthreshold > 15)
                bs->bs_bmissthreshold = 15;
        else if (bs->bs_bmissthreshold <= 0)
                bs->bs_bmissthreshold = 1;

        /*
         * Calculate sleep duration. The configuration is given in ms.
         * We ensure a multiple of the beacon period is used. Also, if the sleep
         * duration is greater than the DTIM period then it makes senses
         * to make it a multiple of that.
         *
         * XXX fixed at 100ms
         */

        bs->bs_sleepduration = TU_TO_USEC(roundup(IEEE80211_MS_TO_TU(100),
                                                  conf->intval));
        if (bs->bs_sleepduration > bs->bs_dtimperiod)
                bs->bs_sleepduration = bs->bs_dtimperiod;

        /* TSF out of range threshold fixed at 1 second */
        bs->bs_tsfoor_threshold = ATH9K_TSFOOR_THRESHOLD;

        ath_dbg(common, BEACON, "bmiss: %u sleep: %u\n",
                bs->bs_bmissthreshold, bs->bs_sleepduration);
        return 0;
}
EXPORT_SYMBOL(ath9k_cmn_beacon_config_sta);

void ath9k_cmn_beacon_config_adhoc(struct ath_hw *ah,
                                   struct ath_beacon_config *conf)
{
        struct ath_common *common = ath9k_hw_common(ah);

        conf->intval = TU_TO_USEC(conf->beacon_interval);

        if (conf->ibss_creator)
                conf->nexttbtt = conf->intval;
        else
                conf->nexttbtt = ath9k_get_next_tbtt(ah, ath9k_hw_gettsf64(ah),
                                               conf->beacon_interval);

        if (conf->enable_beacon)
                ah->imask |= ATH9K_INT_SWBA;
        else
                ah->imask &= ~ATH9K_INT_SWBA;

        ath_dbg(common, BEACON,
                "IBSS (%s) nexttbtt: %u intval: %u conf_intval: %u\n",
                (conf->enable_beacon) ? "Enable" : "Disable",
                conf->nexttbtt, conf->intval, conf->beacon_interval);
}
EXPORT_SYMBOL(ath9k_cmn_beacon_config_adhoc);

/*
 * For multi-bss ap support beacons are either staggered evenly over N slots or
 * burst together.  For the former arrange for the SWBA to be delivered for each
 * slot. Slots that are not occupied will generate nothing.
 */
void ath9k_cmn_beacon_config_ap(struct ath_hw *ah,
                                struct ath_beacon_config *conf,
                                unsigned int bc_buf)
{
        struct ath_common *common = ath9k_hw_common(ah);

        /* NB: the beacon interval is kept internally in TU's */
        conf->intval = TU_TO_USEC(conf->beacon_interval);
        conf->intval /= bc_buf;
        conf->nexttbtt = ath9k_get_next_tbtt(ah, ath9k_hw_gettsf64(ah),
                                       conf->beacon_interval);

        if (conf->enable_beacon)
                ah->imask |= ATH9K_INT_SWBA;
        else
                ah->imask &= ~ATH9K_INT_SWBA;

        ath_dbg(common, BEACON,
                "AP (%s) nexttbtt: %u intval: %u conf_intval: %u\n",
                (conf->enable_beacon) ? "Enable" : "Disable",
                conf->nexttbtt, conf->intval, conf->beacon_interval);
}
EXPORT_SYMBOL(ath9k_cmn_beacon_config_ap);