zd_mac.c

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/* ZD1211 USB-WLAN driver for Linux
 *
 * Copyright (C) 2005-2007 Ulrich Kunitz <[email protected]>
 * Copyright (C) 2006-2007 Daniel Drake <[email protected]>
 * Copyright (C) 2006-2007 Michael Wu <[email protected]>
 * Copyright (C) 2007-2008 Luis R. Rodriguez <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/jiffies.h>
#include <net/ieee80211_radiotap.h>

#include "zd_def.h"
#include "zd_chip.h"
#include "zd_mac.h"
#include "zd_rf.h"

struct zd_reg_alpha2_map {
    u32 reg;
    char alpha2[2];
};

static struct zd_reg_alpha2_map reg_alpha2_map[] = {
    { ZD_REGDOMAIN_FCC, "US" },
    { ZD_REGDOMAIN_IC, "CA" },
    { ZD_REGDOMAIN_ETSI, "DE" }, /* Generic ETSI, use most restrictive */
    { ZD_REGDOMAIN_JAPAN, "JP" },
    { ZD_REGDOMAIN_JAPAN_2, "JP" },
    { ZD_REGDOMAIN_JAPAN_3, "JP" },
    { ZD_REGDOMAIN_SPAIN, "ES" },
    { ZD_REGDOMAIN_FRANCE, "FR" },
};

/* This table contains the hardware specific values for the modulation rates. */
static const struct ieee80211_rate zd_rates[] = {
    { .bitrate = 10,
      .hw_value = ZD_CCK_RATE_1M, },
    { .bitrate = 20,
      .hw_value = ZD_CCK_RATE_2M,
      .hw_value_short = ZD_CCK_RATE_2M | ZD_CCK_PREA_SHORT,
      .flags = IEEE80211_RATE_SHORT_PREAMBLE },
    { .bitrate = 55,
      .hw_value = ZD_CCK_RATE_5_5M,
      .hw_value_short = ZD_CCK_RATE_5_5M | ZD_CCK_PREA_SHORT,
      .flags = IEEE80211_RATE_SHORT_PREAMBLE },
    { .bitrate = 110,
      .hw_value = ZD_CCK_RATE_11M,
      .hw_value_short = ZD_CCK_RATE_11M | ZD_CCK_PREA_SHORT,
      .flags = IEEE80211_RATE_SHORT_PREAMBLE },
    { .bitrate = 60,
      .hw_value = ZD_OFDM_RATE_6M,
      .flags = 0 },
    { .bitrate = 90,
      .hw_value = ZD_OFDM_RATE_9M,
      .flags = 0 },
    { .bitrate = 120,
      .hw_value = ZD_OFDM_RATE_12M,
      .flags = 0 },
    { .bitrate = 180,
      .hw_value = ZD_OFDM_RATE_18M,
      .flags = 0 },
    { .bitrate = 240,
      .hw_value = ZD_OFDM_RATE_24M,
      .flags = 0 },
    { .bitrate = 360,
      .hw_value = ZD_OFDM_RATE_36M,
      .flags = 0 },
    { .bitrate = 480,
      .hw_value = ZD_OFDM_RATE_48M,
      .flags = 0 },
    { .bitrate = 540,
      .hw_value = ZD_OFDM_RATE_54M,
      .flags = 0 },
};

/*
 * Zydas retry rates table. Each line is listed in the same order as
 * in zd_rates[] and contains all the rate used when a packet is sent
 * starting with a given rates. Let's consider an example :
 *
 * "11 Mbits : 4, 3, 2, 1, 0" means :
 * - packet is sent using 4 different rates
 * - 1st rate is index 3 (ie 11 Mbits)
 * - 2nd rate is index 2 (ie 5.5 Mbits)
 * - 3rd rate is index 1 (ie 2 Mbits)
 * - 4th rate is index 0 (ie 1 Mbits)
 */

static const struct tx_retry_rate zd_retry_rates[] = {
    { /*  1 Mbits */    1, { 0 }},
    { /*  2 Mbits */    2, { 1,  0 }},
    { /*  5.5 Mbits */  3, { 2,  1, 0 }},
    { /* 11 Mbits */    4, { 3,  2, 1, 0 }},
    { /*  6 Mbits */    5, { 4,  3, 2, 1, 0 }},
    { /*  9 Mbits */    6, { 5,  4, 3, 2, 1, 0}},
    { /* 12 Mbits */    5, { 6,  3, 2, 1, 0 }},
    { /* 18 Mbits */    6, { 7,  6, 3, 2, 1, 0 }},
    { /* 24 Mbits */    6, { 8,  6, 3, 2, 1, 0 }},
    { /* 36 Mbits */    7, { 9,  8, 6, 3, 2, 1, 0 }},
    { /* 48 Mbits */    8, {10,  9, 8, 6, 3, 2, 1, 0 }},
    { /* 54 Mbits */    9, {11, 10, 9, 8, 6, 3, 2, 1, 0 }}
};

static const struct ieee80211_channel zd_channels[] = {
    { .center_freq = 2412, .hw_value = 1 },
    { .center_freq = 2417, .hw_value = 2 },
    { .center_freq = 2422, .hw_value = 3 },
    { .center_freq = 2427, .hw_value = 4 },
    { .center_freq = 2432, .hw_value = 5 },
    { .center_freq = 2437, .hw_value = 6 },
    { .center_freq = 2442, .hw_value = 7 },
    { .center_freq = 2447, .hw_value = 8 },
    { .center_freq = 2452, .hw_value = 9 },
    { .center_freq = 2457, .hw_value = 10 },
    { .center_freq = 2462, .hw_value = 11 },
    { .center_freq = 2467, .hw_value = 12 },
    { .center_freq = 2472, .hw_value = 13 },
    { .center_freq = 2484, .hw_value = 14 },
};

static void housekeeping_init(struct zd_mac *mac);
static void housekeeping_enable(struct zd_mac *mac);
static void housekeeping_disable(struct zd_mac *mac);
static void beacon_init(struct zd_mac *mac);
static void beacon_enable(struct zd_mac *mac);
static void beacon_disable(struct zd_mac *mac);
static void set_rts_cts(struct zd_mac *mac, unsigned int short_preamble);
static int zd_mac_config_beacon(struct ieee80211_hw *hw,
                struct sk_buff *beacon, bool in_intr);

static int zd_reg2alpha2(u8 regdomain, char *alpha2)
{
    unsigned int i;
    struct zd_reg_alpha2_map *reg_map;
    for (i = 0; i < ARRAY_SIZE(reg_alpha2_map); i++) {
        reg_map = &reg_alpha2_map[i];
        if (regdomain == reg_map->reg) {
            alpha2[0] = reg_map->alpha2[0];
            alpha2[1] = reg_map->alpha2[1];
            return 0;
        }
    }
    return 1;
}

static int zd_check_signal(struct ieee80211_hw *hw, int signal)
{
    struct zd_mac *mac = zd_hw_mac(hw);

    dev_dbg_f_cond(zd_mac_dev(mac), signal < 0 || signal > 100,
            "%s: signal value from device not in range 0..100, "
            "but %d.\n", __func__, signal);

    if (signal < 0)
        signal = 0;
    else if (signal > 100)
        signal = 100;

    return signal;
}

int zd_mac_preinit_hw(struct ieee80211_hw *hw)
{
    int r;
    u8 addr[ETH_ALEN];
    struct zd_mac *mac = zd_hw_mac(hw);

    r = zd_chip_read_mac_addr_fw(&mac->chip, addr);
    if (r)
        return r;

    SET_IEEE80211_PERM_ADDR(hw, addr);

    return 0;
}

int zd_mac_init_hw(struct ieee80211_hw *hw)
{
    int r;
    struct zd_mac *mac = zd_hw_mac(hw);
    struct zd_chip *chip = &mac->chip;
    char alpha2[2];
    u8 default_regdomain;

    r = zd_chip_enable_int(chip);
    if (r)
        goto out;
    r = zd_chip_init_hw(chip);
    if (r)
        goto disable_int;

    ZD_ASSERT(!irqs_disabled());

    r = zd_read_regdomain(chip, &default_regdomain);
    if (r)
        goto disable_int;
    spin_lock_irq(&mac->lock);
    mac->regdomain = mac->default_regdomain = default_regdomain;
    spin_unlock_irq(&mac->lock);

    /* We must inform the device that we are doing encryption/decryption in
     * software at the moment. */
    r = zd_set_encryption_type(chip, ENC_SNIFFER);
    if (r)
        goto disable_int;

    r = zd_reg2alpha2(mac->regdomain, alpha2);
    if (r)
        goto disable_int;

    r = regulatory_hint(hw->wiphy, alpha2);
disable_int:
    zd_chip_disable_int(chip);
out:
    return r;
}

void zd_mac_clear(struct zd_mac *mac)
{
    flush_workqueue(zd_workqueue);
    zd_chip_clear(&mac->chip);
    ZD_ASSERT(!spin_is_locked(&mac->lock));
    ZD_MEMCLEAR(mac, sizeof(struct zd_mac));
}

static int set_rx_filter(struct zd_mac *mac)
{
    unsigned long flags;
    u32 filter = STA_RX_FILTER;

    spin_lock_irqsave(&mac->lock, flags);
    if (mac->pass_ctrl)
        filter |= RX_FILTER_CTRL;
    spin_unlock_irqrestore(&mac->lock, flags);

    return zd_iowrite32(&mac->chip, CR_RX_FILTER, filter);
}

static int set_mac_and_bssid(struct zd_mac *mac)
{
    int r;

    if (!mac->vif)
        return -1;

    r = zd_write_mac_addr(&mac->chip, mac->vif->addr);
    if (r)
        return r;

    /* Vendor driver after setting MAC either sets BSSID for AP or
     * filter for other modes.
     */
    if (mac->type != NL80211_IFTYPE_AP)
        return set_rx_filter(mac);
    else
        return zd_write_bssid(&mac->chip, mac->vif->addr);
}

static int set_mc_hash(struct zd_mac *mac)
{
    struct zd_mc_hash hash;
    zd_mc_clear(&hash);
    return zd_chip_set_multicast_hash(&mac->chip, &hash);
}

int zd_op_start(struct ieee80211_hw *hw)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct zd_chip *chip = &mac->chip;
    struct zd_usb *usb = &chip->usb;
    int r;

    if (!usb->initialized) {
        r = zd_usb_init_hw(usb);
        if (r)
            goto out;
    }

    r = zd_chip_enable_int(chip);
    if (r < 0)
        goto out;

    r = zd_chip_set_basic_rates(chip, CR_RATES_80211B | CR_RATES_80211G);
    if (r < 0)
        goto disable_int;
    r = set_rx_filter(mac);
    if (r)
        goto disable_int;
    r = set_mc_hash(mac);
    if (r)
        goto disable_int;

    /* Wait after setting the multicast hash table and powering on
     * the radio otherwise interface bring up will fail. This matches
     * what the vendor driver did.
     */
    msleep(10);

    r = zd_chip_switch_radio_on(chip);
    if (r < 0) {
        dev_err(zd_chip_dev(chip),
            "%s: failed to set radio on\n", __func__);
        goto disable_int;
    }
    r = zd_chip_enable_rxtx(chip);
    if (r < 0)
        goto disable_radio;
    r = zd_chip_enable_hwint(chip);
    if (r < 0)
        goto disable_rxtx;

    housekeeping_enable(mac);
    beacon_enable(mac);
    set_bit(ZD_DEVICE_RUNNING, &mac->flags);
    return 0;
disable_rxtx:
    zd_chip_disable_rxtx(chip);
disable_radio:
    zd_chip_switch_radio_off(chip);
disable_int:
    zd_chip_disable_int(chip);
out:
    return r;
}

void zd_op_stop(struct ieee80211_hw *hw)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct zd_chip *chip = &mac->chip;
    struct sk_buff *skb;
    struct sk_buff_head *ack_wait_queue = &mac->ack_wait_queue;

    clear_bit(ZD_DEVICE_RUNNING, &mac->flags);

    /* The order here deliberately is a little different from the open()
     * method, since we need to make sure there is no opportunity for RX
     * frames to be processed by mac80211 after we have stopped it.
     */

    zd_chip_disable_rxtx(chip);
    beacon_disable(mac);
    housekeeping_disable(mac);
    flush_workqueue(zd_workqueue);

    zd_chip_disable_hwint(chip);
    zd_chip_switch_radio_off(chip);
    zd_chip_disable_int(chip);


    while ((skb = skb_dequeue(ack_wait_queue)))
        dev_kfree_skb_any(skb);
}

int zd_restore_settings(struct zd_mac *mac)
{
    struct sk_buff *beacon;
    struct zd_mc_hash multicast_hash;
    unsigned int short_preamble;
    int r, beacon_interval, beacon_period;
    u8 channel;

    dev_dbg_f(zd_mac_dev(mac), "\n");

    spin_lock_irq(&mac->lock);
    multicast_hash = mac->multicast_hash;
    short_preamble = mac->short_preamble;
    beacon_interval = mac->beacon.interval;
    beacon_period = mac->beacon.period;
    channel = mac->channel;
    spin_unlock_irq(&mac->lock);

    r = set_mac_and_bssid(mac);
    if (r < 0) {
        dev_dbg_f(zd_mac_dev(mac), "set_mac_and_bssid failed, %d\n", r);
        return r;
    }

    r = zd_chip_set_channel(&mac->chip, channel);
    if (r < 0) {
        dev_dbg_f(zd_mac_dev(mac), "zd_chip_set_channel failed, %d\n",
              r);
        return r;
    }

    set_rts_cts(mac, short_preamble);

    r = zd_chip_set_multicast_hash(&mac->chip, &multicast_hash);
    if (r < 0) {
        dev_dbg_f(zd_mac_dev(mac),
              "zd_chip_set_multicast_hash failed, %d\n", r);
        return r;
    }

    if (mac->type == NL80211_IFTYPE_MESH_POINT ||
        mac->type == NL80211_IFTYPE_ADHOC ||
        mac->type == NL80211_IFTYPE_AP) {
        if (mac->vif != NULL) {
            beacon = ieee80211_beacon_get(mac->hw, mac->vif);
            if (beacon)
                zd_mac_config_beacon(mac->hw, beacon, false);
        }

        zd_set_beacon_interval(&mac->chip, beacon_interval,
                    beacon_period, mac->type);

        spin_lock_irq(&mac->lock);
        mac->beacon.last_update = jiffies;
        spin_unlock_irq(&mac->lock);
    }

    return 0;
}

static void zd_mac_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
              int ackssi, struct tx_status *tx_status)
{
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
    int i;
    int success = 1, retry = 1;
    int first_idx;
    const struct tx_retry_rate *retries;

    ieee80211_tx_info_clear_status(info);

    if (tx_status) {
        success = !tx_status->failure;
        retry = tx_status->retry + success;
    }

    if (success) {
        /* success */
        info->flags |= IEEE80211_TX_STAT_ACK;
    } else {
        /* failure */
        info->flags &= ~IEEE80211_TX_STAT_ACK;
    }

    first_idx = info->status.rates[0].idx;
    ZD_ASSERT(0<=first_idx && first_idx<ARRAY_SIZE(zd_retry_rates));
    retries = &zd_retry_rates[first_idx];
    ZD_ASSERT(1 <= retry && retry <= retries->count);

    info->status.rates[0].idx = retries->rate[0];
    info->status.rates[0].count = 1; // (retry > 1 ? 2 : 1);

    for (i=1; i<IEEE80211_TX_MAX_RATES-1 && i<retry; i++) {
        info->status.rates[i].idx = retries->rate[i];
        info->status.rates[i].count = 1; // ((i==retry-1) && success ? 1:2);
    }
    for (; i<IEEE80211_TX_MAX_RATES && i<retry; i++) {
        info->status.rates[i].idx = retries->rate[retry - 1];
        info->status.rates[i].count = 1; // (success ? 1:2);
    }
    if (i<IEEE80211_TX_MAX_RATES)
        info->status.rates[i].idx = -1; /* terminate */

    info->status.ack_signal = zd_check_signal(hw, ackssi);
    ieee80211_tx_status_irqsafe(hw, skb);
}

void zd_mac_tx_failed(struct urb *urb)
{
    struct ieee80211_hw * hw = zd_usb_to_hw(urb->context);
    struct zd_mac *mac = zd_hw_mac(hw);
    struct sk_buff_head *q = &mac->ack_wait_queue;
    struct sk_buff *skb;
    struct tx_status *tx_status = (struct tx_status *)urb->transfer_buffer;
    unsigned long flags;
    int success = !tx_status->failure;
    int retry = tx_status->retry + success;
    int found = 0;
    int i, position = 0;

    q = &mac->ack_wait_queue;
    spin_lock_irqsave(&q->lock, flags);

    skb_queue_walk(q, skb) {
        struct ieee80211_hdr *tx_hdr;
        struct ieee80211_tx_info *info;
        int first_idx, final_idx;
        const struct tx_retry_rate *retries;
        u8 final_rate;

        position ++;

        /* if the hardware reports a failure and we had a 802.11 ACK
         * pending, then we skip the first skb when searching for a
         * matching frame */
        if (tx_status->failure && mac->ack_pending &&
            skb_queue_is_first(q, skb)) {
            continue;
        }

        tx_hdr = (struct ieee80211_hdr *)skb->data;

        /* we skip all frames not matching the reported destination */
        if (unlikely(memcmp(tx_hdr->addr1, tx_status->mac, ETH_ALEN))) {
            continue;
        }

        /* we skip all frames not matching the reported final rate */

        info = IEEE80211_SKB_CB(skb);
        first_idx = info->status.rates[0].idx;
        ZD_ASSERT(0<=first_idx && first_idx<ARRAY_SIZE(zd_retry_rates));
        retries = &zd_retry_rates[first_idx];
        if (retry <= 0 || retry > retries->count)
            continue;

        final_idx = retries->rate[retry - 1];
        final_rate = zd_rates[final_idx].hw_value;

        if (final_rate != tx_status->rate) {
            continue;
        }

        found = 1;
        break;
    }

    if (found) {
        for (i=1; i<=position; i++) {
            skb = __skb_dequeue(q);
            zd_mac_tx_status(hw, skb,
                     mac->ack_pending ? mac->ack_signal : 0,
                     i == position ? tx_status : NULL);
            mac->ack_pending = 0;
        }
    }

    spin_unlock_irqrestore(&q->lock, flags);
}

void zd_mac_tx_to_dev(struct sk_buff *skb, int error)
{
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
    struct ieee80211_hw *hw = info->rate_driver_data[0];
    struct zd_mac *mac = zd_hw_mac(hw);

    ieee80211_tx_info_clear_status(info);

    skb_pull(skb, sizeof(struct zd_ctrlset));
    if (unlikely(error ||
        (info->flags & IEEE80211_TX_CTL_NO_ACK))) {
        /*
         * FIXME : do we need to fill in anything ?
         */
        ieee80211_tx_status_irqsafe(hw, skb);
    } else {
        struct sk_buff_head *q = &mac->ack_wait_queue;

        skb_queue_tail(q, skb);
        while (skb_queue_len(q) > ZD_MAC_MAX_ACK_WAITERS) {
            zd_mac_tx_status(hw, skb_dequeue(q),
                     mac->ack_pending ? mac->ack_signal : 0,
                     NULL);
            mac->ack_pending = 0;
        }
    }
}

static int zd_calc_tx_length_us(u8 *service, u8 zd_rate, u16 tx_length)
{
    /* ZD_PURE_RATE() must be used to remove the modulation type flag of
     * the zd-rate values.
     */
    static const u8 rate_divisor[] = {
        [ZD_PURE_RATE(ZD_CCK_RATE_1M)]   =  1,
        [ZD_PURE_RATE(ZD_CCK_RATE_2M)]   =  2,
        /* Bits must be doubled. */
        [ZD_PURE_RATE(ZD_CCK_RATE_5_5M)] = 11,
        [ZD_PURE_RATE(ZD_CCK_RATE_11M)]  = 11,
        [ZD_PURE_RATE(ZD_OFDM_RATE_6M)]  =  6,
        [ZD_PURE_RATE(ZD_OFDM_RATE_9M)]  =  9,
        [ZD_PURE_RATE(ZD_OFDM_RATE_12M)] = 12,
        [ZD_PURE_RATE(ZD_OFDM_RATE_18M)] = 18,
        [ZD_PURE_RATE(ZD_OFDM_RATE_24M)] = 24,
        [ZD_PURE_RATE(ZD_OFDM_RATE_36M)] = 36,
        [ZD_PURE_RATE(ZD_OFDM_RATE_48M)] = 48,
        [ZD_PURE_RATE(ZD_OFDM_RATE_54M)] = 54,
    };

    u32 bits = (u32)tx_length * 8;
    u32 divisor;

    divisor = rate_divisor[ZD_PURE_RATE(zd_rate)];
    if (divisor == 0)
        return -EINVAL;

    switch (zd_rate) {
    case ZD_CCK_RATE_5_5M:
        bits = (2*bits) + 10; /* round up to the next integer */
        break;
    case ZD_CCK_RATE_11M:
        if (service) {
            u32 t = bits % 11;
            *service &= ~ZD_PLCP_SERVICE_LENGTH_EXTENSION;
            if (0 < t && t <= 3) {
                *service |= ZD_PLCP_SERVICE_LENGTH_EXTENSION;
            }
        }
        bits += 10; /* round up to the next integer */
        break;
    }

    return bits/divisor;
}

static void cs_set_control(struct zd_mac *mac, struct zd_ctrlset *cs,
                       struct ieee80211_hdr *header,
                       struct ieee80211_tx_info *info)
{
    /*
     * CONTROL TODO:
     * - if backoff needed, enable bit 0
     * - if burst (backoff not needed) disable bit 0
     */

    cs->control = 0;

    /* First fragment */
    if (info->flags & IEEE80211_TX_CTL_FIRST_FRAGMENT)
        cs->control |= ZD_CS_NEED_RANDOM_BACKOFF;

    /* No ACK expected (multicast, etc.) */
    if (info->flags & IEEE80211_TX_CTL_NO_ACK)
        cs->control |= ZD_CS_NO_ACK;

    /* PS-POLL */
    if (ieee80211_is_pspoll(header->frame_control))
        cs->control |= ZD_CS_PS_POLL_FRAME;

    if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)
        cs->control |= ZD_CS_RTS;

    if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT)
        cs->control |= ZD_CS_SELF_CTS;

    /* FIXME: Management frame? */
}

static bool zd_mac_match_cur_beacon(struct zd_mac *mac, struct sk_buff *beacon)
{
    if (!mac->beacon.cur_beacon)
        return false;

    if (mac->beacon.cur_beacon->len != beacon->len)
        return false;

    return !memcmp(beacon->data, mac->beacon.cur_beacon->data, beacon->len);
}

static void zd_mac_free_cur_beacon_locked(struct zd_mac *mac)
{
    ZD_ASSERT(mutex_is_locked(&mac->chip.mutex));

    kfree_skb(mac->beacon.cur_beacon);
    mac->beacon.cur_beacon = NULL;
}

static void zd_mac_free_cur_beacon(struct zd_mac *mac)
{
    mutex_lock(&mac->chip.mutex);
    zd_mac_free_cur_beacon_locked(mac);
    mutex_unlock(&mac->chip.mutex);
}

static int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon,
                bool in_intr)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    int r, ret, num_cmds, req_pos = 0;
    u32 tmp, j = 0;
    /* 4 more bytes for tail CRC */
    u32 full_len = beacon->len + 4;
    unsigned long end_jiffies, message_jiffies;
    struct zd_ioreq32 *ioreqs;

    mutex_lock(&mac->chip.mutex);

    /* Check if hw already has this beacon. */
    if (zd_mac_match_cur_beacon(mac, beacon)) {
        r = 0;
        goto out_nofree;
    }

    /* Alloc memory for full beacon write at once. */
    num_cmds = 1 + zd_chip_is_zd1211b(&mac->chip) + full_len;
    ioreqs = kmalloc(num_cmds * sizeof(struct zd_ioreq32), GFP_KERNEL);
    if (!ioreqs) {
        r = -ENOMEM;
        goto out_nofree;
    }

    r = zd_iowrite32_locked(&mac->chip, 0, CR_BCN_FIFO_SEMAPHORE);
    if (r < 0)
        goto out;
    r = zd_ioread32_locked(&mac->chip, &tmp, CR_BCN_FIFO_SEMAPHORE);
    if (r < 0)
        goto release_sema;
    if (in_intr && tmp & 0x2) {
        r = -EBUSY;
        goto release_sema;
    }

    end_jiffies = jiffies + HZ / 2; /*~500ms*/
    message_jiffies = jiffies + HZ / 10; /*~100ms*/
    while (tmp & 0x2) {
        r = zd_ioread32_locked(&mac->chip, &tmp, CR_BCN_FIFO_SEMAPHORE);
        if (r < 0)
            goto release_sema;
        if (time_is_before_eq_jiffies(message_jiffies)) {
            message_jiffies = jiffies + HZ / 10;
            dev_err(zd_mac_dev(mac),
                    "CR_BCN_FIFO_SEMAPHORE not ready\n");
            if (time_is_before_eq_jiffies(end_jiffies))  {
                dev_err(zd_mac_dev(mac),
                        "Giving up beacon config.\n");
                r = -ETIMEDOUT;
                goto reset_device;
            }
        }
        msleep(20);
    }

    ioreqs[req_pos].addr = CR_BCN_FIFO;
    ioreqs[req_pos].value = full_len - 1;
    req_pos++;
    if (zd_chip_is_zd1211b(&mac->chip)) {
        ioreqs[req_pos].addr = CR_BCN_LENGTH;
        ioreqs[req_pos].value = full_len - 1;
        req_pos++;
    }

    for (j = 0 ; j < beacon->len; j++) {
        ioreqs[req_pos].addr = CR_BCN_FIFO;
        ioreqs[req_pos].value = *((u8 *)(beacon->data + j));
        req_pos++;
    }

    for (j = 0; j < 4; j++) {
        ioreqs[req_pos].addr = CR_BCN_FIFO;
        ioreqs[req_pos].value = 0x0;
        req_pos++;
    }

    BUG_ON(req_pos != num_cmds);

    r = zd_iowrite32a_locked(&mac->chip, ioreqs, num_cmds);

release_sema:
    /*
     * Try very hard to release device beacon semaphore, as otherwise
     * device/driver can be left in unusable state.
     */
    end_jiffies = jiffies + HZ / 2; /*~500ms*/
    ret = zd_iowrite32_locked(&mac->chip, 1, CR_BCN_FIFO_SEMAPHORE);
    while (ret < 0) {
        if (in_intr || time_is_before_eq_jiffies(end_jiffies)) {
            ret = -ETIMEDOUT;
            break;
        }

        msleep(20);
        ret = zd_iowrite32_locked(&mac->chip, 1, CR_BCN_FIFO_SEMAPHORE);
    }

    if (ret < 0)
        dev_err(zd_mac_dev(mac), "Could not release "
                     "CR_BCN_FIFO_SEMAPHORE!\n");
    if (r < 0 || ret < 0) {
        if (r >= 0)
            r = ret;

        /* We don't know if beacon was written successfully or not,
         * so clear current. */
        zd_mac_free_cur_beacon_locked(mac);

        goto out;
    }

    /* Beacon has now been written successfully, update current. */
    zd_mac_free_cur_beacon_locked(mac);
    mac->beacon.cur_beacon = beacon;
    beacon = NULL;

    /* 802.11b/g 2.4G CCK 1Mb
     * 802.11a, not yet implemented, uses different values (see GPL vendor
     * driver)
     */
    r = zd_iowrite32_locked(&mac->chip, 0x00000400 | (full_len << 19),
                CR_BCN_PLCP_CFG);
out:
    kfree(ioreqs);
out_nofree:
    kfree_skb(beacon);
    mutex_unlock(&mac->chip.mutex);

    return r;

reset_device:
    zd_mac_free_cur_beacon_locked(mac);
    kfree_skb(beacon);

    mutex_unlock(&mac->chip.mutex);
    kfree(ioreqs);

    /* semaphore stuck, reset device to avoid fw freeze later */
    dev_warn(zd_mac_dev(mac), "CR_BCN_FIFO_SEMAPHORE stuck, "
                  "resetting device...");
    usb_queue_reset_device(mac->chip.usb.intf);

    return r;
}

static int fill_ctrlset(struct zd_mac *mac,
            struct sk_buff *skb)
{
    int r;
    struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
    unsigned int frag_len = skb->len + FCS_LEN;
    unsigned int packet_length;
    struct ieee80211_rate *txrate;
    struct zd_ctrlset *cs = (struct zd_ctrlset *)
        skb_push(skb, sizeof(struct zd_ctrlset));
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

    ZD_ASSERT(frag_len <= 0xffff);

    /*
     * Firmware computes the duration itself (for all frames except PSPoll)
     * and needs the field set to 0 at input, otherwise firmware messes up
     * duration_id and sets bits 14 and 15 on.
     */
    if (!ieee80211_is_pspoll(hdr->frame_control))
        hdr->duration_id = 0;

    txrate = ieee80211_get_tx_rate(mac->hw, info);

    cs->modulation = txrate->hw_value;
    if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE)
        cs->modulation = txrate->hw_value_short;

    cs->tx_length = cpu_to_le16(frag_len);

    cs_set_control(mac, cs, hdr, info);

    packet_length = frag_len + sizeof(struct zd_ctrlset) + 10;
    ZD_ASSERT(packet_length <= 0xffff);
    /* ZD1211B: Computing the length difference this way, gives us
     * flexibility to compute the packet length.
     */
    cs->packet_length = cpu_to_le16(zd_chip_is_zd1211b(&mac->chip) ?
            packet_length - frag_len : packet_length);

    /*
     * CURRENT LENGTH:
     * - transmit frame length in microseconds
     * - seems to be derived from frame length
     * - see Cal_Us_Service() in zdinlinef.h
     * - if macp->bTxBurstEnable is enabled, then multiply by 4
     *  - bTxBurstEnable is never set in the vendor driver
     *
     * SERVICE:
     * - "for PLCP configuration"
     * - always 0 except in some situations at 802.11b 11M
     * - see line 53 of zdinlinef.h
     */
    cs->service = 0;
    r = zd_calc_tx_length_us(&cs->service, ZD_RATE(cs->modulation),
                         le16_to_cpu(cs->tx_length));
    if (r < 0)
        return r;
    cs->current_length = cpu_to_le16(r);
    cs->next_frame_length = 0;

    return 0;
}

static void zd_op_tx(struct ieee80211_hw *hw,
             struct ieee80211_tx_control *control,
             struct sk_buff *skb)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
    int r;

    r = fill_ctrlset(mac, skb);
    if (r)
        goto fail;

    info->rate_driver_data[0] = hw;

    r = zd_usb_tx(&mac->chip.usb, skb);
    if (r)
        goto fail;
    return;

fail:
    dev_kfree_skb(skb);
}

static int filter_ack(struct ieee80211_hw *hw, struct ieee80211_hdr *rx_hdr,
              struct ieee80211_rx_status *stats)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct sk_buff *skb;
    struct sk_buff_head *q;
    unsigned long flags;
    int found = 0;
    int i, position = 0;

    if (!ieee80211_is_ack(rx_hdr->frame_control))
        return 0;

    q = &mac->ack_wait_queue;
    spin_lock_irqsave(&q->lock, flags);
    skb_queue_walk(q, skb) {
        struct ieee80211_hdr *tx_hdr;

        position ++;

        if (mac->ack_pending && skb_queue_is_first(q, skb))
            continue;

        tx_hdr = (struct ieee80211_hdr *)skb->data;
        if (likely(!memcmp(tx_hdr->addr2, rx_hdr->addr1, ETH_ALEN)))
        {
            found = 1;
            break;
        }
    }

    if (found) {
        for (i=1; i<position; i++) {
            skb = __skb_dequeue(q);
            zd_mac_tx_status(hw, skb,
                     mac->ack_pending ? mac->ack_signal : 0,
                     NULL);
            mac->ack_pending = 0;
        }

        mac->ack_pending = 1;
        mac->ack_signal = stats->signal;

        /* Prevent pending tx-packet on AP-mode */
        if (mac->type == NL80211_IFTYPE_AP) {
            skb = __skb_dequeue(q);
            zd_mac_tx_status(hw, skb, mac->ack_signal, NULL);
            mac->ack_pending = 0;
        }
    }

    spin_unlock_irqrestore(&q->lock, flags);
    return 1;
}

int zd_mac_rx(struct ieee80211_hw *hw, const u8 *buffer, unsigned int length)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct ieee80211_rx_status stats;
    const struct rx_status *status;
    struct sk_buff *skb;
    int bad_frame = 0;
    __le16 fc;
    int need_padding;
    int i;
    u8 rate;

    if (length < ZD_PLCP_HEADER_SIZE + 10 /* IEEE80211_1ADDR_LEN */ +
                 FCS_LEN + sizeof(struct rx_status))
        return -EINVAL;

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

    /* Note about pass_failed_fcs and pass_ctrl access below:
     * mac locking intentionally omitted here, as this is the only unlocked
     * reader and the only writer is configure_filter. Plus, if there were
     * any races accessing these variables, it wouldn't really matter.
     * If mac80211 ever provides a way for us to access filter flags
     * from outside configure_filter, we could improve on this. Also, this
     * situation may change once we implement some kind of DMA-into-skb
     * RX path. */

    /* Caller has to ensure that length >= sizeof(struct rx_status). */
    status = (struct rx_status *)
        (buffer + (length - sizeof(struct rx_status)));
    if (status->frame_status & ZD_RX_ERROR) {
        if (mac->pass_failed_fcs &&
                (status->frame_status & ZD_RX_CRC32_ERROR)) {
            stats.flag |= RX_FLAG_FAILED_FCS_CRC;
            bad_frame = 1;
        } else {
            return -EINVAL;
        }
    }

    stats.freq = zd_channels[_zd_chip_get_channel(&mac->chip) - 1].center_freq;
    stats.band = IEEE80211_BAND_2GHZ;
    stats.signal = zd_check_signal(hw, status->signal_strength);

    rate = zd_rx_rate(buffer, status);

    /* todo: return index in the big switches in zd_rx_rate instead */
    for (i = 0; i < mac->band.n_bitrates; i++)
        if (rate == mac->band.bitrates[i].hw_value)
            stats.rate_idx = i;

    length -= ZD_PLCP_HEADER_SIZE + sizeof(struct rx_status);
    buffer += ZD_PLCP_HEADER_SIZE;

    /* Except for bad frames, filter each frame to see if it is an ACK, in
     * which case our internal TX tracking is updated. Normally we then
     * bail here as there's no need to pass ACKs on up to the stack, but
     * there is also the case where the stack has requested us to pass
     * control frames on up (pass_ctrl) which we must consider. */
    if (!bad_frame &&
            filter_ack(hw, (struct ieee80211_hdr *)buffer, &stats)
            && !mac->pass_ctrl)
        return 0;

    fc = get_unaligned((__le16*)buffer);
    need_padding = ieee80211_is_data_qos(fc) ^ ieee80211_has_a4(fc);

    skb = dev_alloc_skb(length + (need_padding ? 2 : 0));
    if (skb == NULL)
        return -ENOMEM;
    if (need_padding) {
        /* Make sure the payload data is 4 byte aligned. */
        skb_reserve(skb, 2);
    }

    /* FIXME : could we avoid this big memcpy ? */
    memcpy(skb_put(skb, length), buffer, length);

    memcpy(IEEE80211_SKB_RXCB(skb), &stats, sizeof(stats));
    ieee80211_rx_irqsafe(hw, skb);
    return 0;
}

static int zd_op_add_interface(struct ieee80211_hw *hw,
                struct ieee80211_vif *vif)
{
    struct zd_mac *mac = zd_hw_mac(hw);

    /* using NL80211_IFTYPE_UNSPECIFIED to indicate no mode selected */
    if (mac->type != NL80211_IFTYPE_UNSPECIFIED)
        return -EOPNOTSUPP;

    switch (vif->type) {
    case NL80211_IFTYPE_MONITOR:
    case NL80211_IFTYPE_MESH_POINT:
    case NL80211_IFTYPE_STATION:
    case NL80211_IFTYPE_ADHOC:
    case NL80211_IFTYPE_AP:
        mac->type = vif->type;
        break;
    default:
        return -EOPNOTSUPP;
    }

    mac->vif = vif;

    return set_mac_and_bssid(mac);
}

static void zd_op_remove_interface(struct ieee80211_hw *hw,
                    struct ieee80211_vif *vif)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    mac->type = NL80211_IFTYPE_UNSPECIFIED;
    mac->vif = NULL;
    zd_set_beacon_interval(&mac->chip, 0, 0, NL80211_IFTYPE_UNSPECIFIED);
    zd_write_mac_addr(&mac->chip, NULL);

    zd_mac_free_cur_beacon(mac);
}

static int zd_op_config(struct ieee80211_hw *hw, u32 changed)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct ieee80211_conf *conf = &hw->conf;

    spin_lock_irq(&mac->lock);
    mac->channel = conf->channel->hw_value;
    spin_unlock_irq(&mac->lock);

    return zd_chip_set_channel(&mac->chip, conf->channel->hw_value);
}

static void zd_beacon_done(struct zd_mac *mac)
{
    struct sk_buff *skb, *beacon;

    if (!test_bit(ZD_DEVICE_RUNNING, &mac->flags))
        return;
    if (!mac->vif || mac->vif->type != NL80211_IFTYPE_AP)
        return;

    /*
     * Send out buffered broad- and multicast frames.
     */
    while (!ieee80211_queue_stopped(mac->hw, 0)) {
        skb = ieee80211_get_buffered_bc(mac->hw, mac->vif);
        if (!skb)
            break;
        zd_op_tx(mac->hw, NULL, skb);
    }

    /*
     * Fetch next beacon so that tim_count is updated.
     */
    beacon = ieee80211_beacon_get(mac->hw, mac->vif);
    if (beacon)
        zd_mac_config_beacon(mac->hw, beacon, true);

    spin_lock_irq(&mac->lock);
    mac->beacon.last_update = jiffies;
    spin_unlock_irq(&mac->lock);
}

static void zd_process_intr(struct work_struct *work)
{
    u16 int_status;
    unsigned long flags;
    struct zd_mac *mac = container_of(work, struct zd_mac, process_intr);

    spin_lock_irqsave(&mac->lock, flags);
    int_status = le16_to_cpu(*(__le16 *)(mac->intr_buffer + 4));
    spin_unlock_irqrestore(&mac->lock, flags);

    if (int_status & INT_CFG_NEXT_BCN) {
        /*dev_dbg_f_limit(zd_mac_dev(mac), "INT_CFG_NEXT_BCN\n");*/
        zd_beacon_done(mac);
    } else {
        dev_dbg_f(zd_mac_dev(mac), "Unsupported interrupt\n");
    }

    zd_chip_enable_hwint(&mac->chip);
}


static u64 zd_op_prepare_multicast(struct ieee80211_hw *hw,
                   struct netdev_hw_addr_list *mc_list)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    struct zd_mc_hash hash;
    struct netdev_hw_addr *ha;

    zd_mc_clear(&hash);

    netdev_hw_addr_list_for_each(ha, mc_list) {
        dev_dbg_f(zd_mac_dev(mac), "mc addr %pM\n", ha->addr);
        zd_mc_add_addr(&hash, ha->addr);
    }

    return hash.low | ((u64)hash.high << 32);
}

#define SUPPORTED_FIF_FLAGS \
    (FIF_PROMISC_IN_BSS | FIF_ALLMULTI | FIF_FCSFAIL | FIF_CONTROL | \
    FIF_OTHER_BSS | FIF_BCN_PRBRESP_PROMISC)
static void zd_op_configure_filter(struct ieee80211_hw *hw,
            unsigned int changed_flags,
            unsigned int *new_flags,
            u64 multicast)
{
    struct zd_mc_hash hash = {
        .low = multicast,
        .high = multicast >> 32,
    };
    struct zd_mac *mac = zd_hw_mac(hw);
    unsigned long flags;
    int r;

    /* Only deal with supported flags */
    changed_flags &= SUPPORTED_FIF_FLAGS;
    *new_flags &= SUPPORTED_FIF_FLAGS;

    /*
     * If multicast parameter (as returned by zd_op_prepare_multicast)
     * has changed, no bit in changed_flags is set. To handle this
     * situation, we do not return if changed_flags is 0. If we do so,
     * we will have some issue with IPv6 which uses multicast for link
     * layer address resolution.
     */
    if (*new_flags & (FIF_PROMISC_IN_BSS | FIF_ALLMULTI))
        zd_mc_add_all(&hash);

    spin_lock_irqsave(&mac->lock, flags);
    mac->pass_failed_fcs = !!(*new_flags & FIF_FCSFAIL);
    mac->pass_ctrl = !!(*new_flags & FIF_CONTROL);
    mac->multicast_hash = hash;
    spin_unlock_irqrestore(&mac->lock, flags);

    zd_chip_set_multicast_hash(&mac->chip, &hash);

    if (changed_flags & FIF_CONTROL) {
        r = set_rx_filter(mac);
        if (r)
            dev_err(zd_mac_dev(mac), "set_rx_filter error %d\n", r);
    }

    /* no handling required for FIF_OTHER_BSS as we don't currently
     * do BSSID filtering */
    /* FIXME: in future it would be nice to enable the probe response
     * filter (so that the driver doesn't see them) until
     * FIF_BCN_PRBRESP_PROMISC is set. however due to atomicity here, we'd
     * have to schedule work to enable prbresp reception, which might
     * happen too late. For now we'll just listen and forward them all the
     * time. */
}

static void set_rts_cts(struct zd_mac *mac, unsigned int short_preamble)
{
    mutex_lock(&mac->chip.mutex);
    zd_chip_set_rts_cts_rate_locked(&mac->chip, short_preamble);
    mutex_unlock(&mac->chip.mutex);
}

static void zd_op_bss_info_changed(struct ieee80211_hw *hw,
                   struct ieee80211_vif *vif,
                   struct ieee80211_bss_conf *bss_conf,
                   u32 changes)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    int associated;

    dev_dbg_f(zd_mac_dev(mac), "changes: %x\n", changes);

    if (mac->type == NL80211_IFTYPE_MESH_POINT ||
        mac->type == NL80211_IFTYPE_ADHOC ||
        mac->type == NL80211_IFTYPE_AP) {
        associated = true;
        if (changes & BSS_CHANGED_BEACON) {
            struct sk_buff *beacon = ieee80211_beacon_get(hw, vif);

            if (beacon) {
                zd_chip_disable_hwint(&mac->chip);
                zd_mac_config_beacon(hw, beacon, false);
                zd_chip_enable_hwint(&mac->chip);
            }
        }

        if (changes & BSS_CHANGED_BEACON_ENABLED) {
            u16 interval = 0;
            u8 period = 0;

            if (bss_conf->enable_beacon) {
                period = bss_conf->dtim_period;
                interval = bss_conf->beacon_int;
            }

            spin_lock_irq(&mac->lock);
            mac->beacon.period = period;
            mac->beacon.interval = interval;
            mac->beacon.last_update = jiffies;
            spin_unlock_irq(&mac->lock);

            zd_set_beacon_interval(&mac->chip, interval, period,
                           mac->type);
        }
    } else
        associated = is_valid_ether_addr(bss_conf->bssid);

    spin_lock_irq(&mac->lock);
    mac->associated = associated;
    spin_unlock_irq(&mac->lock);

    /* TODO: do hardware bssid filtering */

    if (changes & BSS_CHANGED_ERP_PREAMBLE) {
        spin_lock_irq(&mac->lock);
        mac->short_preamble = bss_conf->use_short_preamble;
        spin_unlock_irq(&mac->lock);

        set_rts_cts(mac, bss_conf->use_short_preamble);
    }
}

static u64 zd_op_get_tsf(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
{
    struct zd_mac *mac = zd_hw_mac(hw);
    return zd_chip_get_tsf(&mac->chip);
}

static const struct ieee80211_ops zd_ops = {
    .tx         = zd_op_tx,
    .start          = zd_op_start,
    .stop           = zd_op_stop,
    .add_interface      = zd_op_add_interface,
    .remove_interface   = zd_op_remove_interface,
    .config         = zd_op_config,
    .prepare_multicast  = zd_op_prepare_multicast,
    .configure_filter   = zd_op_configure_filter,
    .bss_info_changed   = zd_op_bss_info_changed,
    .get_tsf        = zd_op_get_tsf,
};

struct ieee80211_hw *zd_mac_alloc_hw(struct usb_interface *intf)
{
    struct zd_mac *mac;
    struct ieee80211_hw *hw;

    hw = ieee80211_alloc_hw(sizeof(struct zd_mac), &zd_ops);
    if (!hw) {
        dev_dbg_f(&intf->dev, "out of memory\n");
        return NULL;
    }

    mac = zd_hw_mac(hw);

    memset(mac, 0, sizeof(*mac));
    spin_lock_init(&mac->lock);
    mac->hw = hw;

    mac->type = NL80211_IFTYPE_UNSPECIFIED;

    memcpy(mac->channels, zd_channels, sizeof(zd_channels));
    memcpy(mac->rates, zd_rates, sizeof(zd_rates));
    mac->band.n_bitrates = ARRAY_SIZE(zd_rates);
    mac->band.bitrates = mac->rates;
    mac->band.n_channels = ARRAY_SIZE(zd_channels);
    mac->band.channels = mac->channels;

    hw->wiphy->bands[IEEE80211_BAND_2GHZ] = &mac->band;

    hw->flags = IEEE80211_HW_RX_INCLUDES_FCS |
            IEEE80211_HW_SIGNAL_UNSPEC |
            IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
            IEEE80211_HW_MFP_CAPABLE;

    hw->wiphy->interface_modes =
        BIT(NL80211_IFTYPE_MESH_POINT) |
        BIT(NL80211_IFTYPE_STATION) |
        BIT(NL80211_IFTYPE_ADHOC) |
        BIT(NL80211_IFTYPE_AP);

    hw->max_signal = 100;
    hw->queues = 1;
    hw->extra_tx_headroom = sizeof(struct zd_ctrlset);

    /*
     * Tell mac80211 that we support multi rate retries
     */
    hw->max_rates = IEEE80211_TX_MAX_RATES;
    hw->max_rate_tries = 18;    /* 9 rates * 2 retries/rate */

    skb_queue_head_init(&mac->ack_wait_queue);
    mac->ack_pending = 0;

    zd_chip_init(&mac->chip, hw, intf);
    housekeeping_init(mac);
    beacon_init(mac);
    INIT_WORK(&mac->process_intr, zd_process_intr);

    SET_IEEE80211_DEV(hw, &intf->dev);
    return hw;
}

#define BEACON_WATCHDOG_DELAY round_jiffies_relative(HZ)

static void beacon_watchdog_handler(struct work_struct *work)
{
    struct zd_mac *mac =
        container_of(work, struct zd_mac, beacon.watchdog_work.work);
    struct sk_buff *beacon;
    unsigned long timeout;
    int interval, period;

    if (!test_bit(ZD_DEVICE_RUNNING, &mac->flags))
        goto rearm;
    if (mac->type != NL80211_IFTYPE_AP || !mac->vif)
        goto rearm;

    spin_lock_irq(&mac->lock);
    interval = mac->beacon.interval;
    period = mac->beacon.period;
    timeout = mac->beacon.last_update +
            msecs_to_jiffies(interval * 1024 / 1000) * 3;
    spin_unlock_irq(&mac->lock);

    if (interval > 0 && time_is_before_jiffies(timeout)) {
        dev_dbg_f(zd_mac_dev(mac), "beacon interrupt stalled, "
                       "restarting. "
                       "(interval: %d, dtim: %d)\n",
                       interval, period);

        zd_chip_disable_hwint(&mac->chip);

        beacon = ieee80211_beacon_get(mac->hw, mac->vif);
        if (beacon) {
            zd_mac_free_cur_beacon(mac);

            zd_mac_config_beacon(mac->hw, beacon, false);
        }

        zd_set_beacon_interval(&mac->chip, interval, period, mac->type);

        zd_chip_enable_hwint(&mac->chip);

        spin_lock_irq(&mac->lock);
        mac->beacon.last_update = jiffies;
        spin_unlock_irq(&mac->lock);
    }

rearm:
    queue_delayed_work(zd_workqueue, &mac->beacon.watchdog_work,
               BEACON_WATCHDOG_DELAY);
}

static void beacon_init(struct zd_mac *mac)
{
    INIT_DELAYED_WORK(&mac->beacon.watchdog_work, beacon_watchdog_handler);
}

static void beacon_enable(struct zd_mac *mac)
{
    dev_dbg_f(zd_mac_dev(mac), "\n");

    mac->beacon.last_update = jiffies;
    queue_delayed_work(zd_workqueue, &mac->beacon.watchdog_work,
               BEACON_WATCHDOG_DELAY);
}

static void beacon_disable(struct zd_mac *mac)
{
    dev_dbg_f(zd_mac_dev(mac), "\n");
    cancel_delayed_work_sync(&mac->beacon.watchdog_work);

    zd_mac_free_cur_beacon(mac);
}

#define LINK_LED_WORK_DELAY HZ

static void link_led_handler(struct work_struct *work)
{
    struct zd_mac *mac =
        container_of(work, struct zd_mac, housekeeping.link_led_work.work);
    struct zd_chip *chip = &mac->chip;
    int is_associated;
    int r;

    if (!test_bit(ZD_DEVICE_RUNNING, &mac->flags))
        goto requeue;

    spin_lock_irq(&mac->lock);
    is_associated = mac->associated;
    spin_unlock_irq(&mac->lock);

    r = zd_chip_control_leds(chip,
                         is_associated ? ZD_LED_ASSOCIATED : ZD_LED_SCANNING);
    if (r)
        dev_dbg_f(zd_mac_dev(mac), "zd_chip_control_leds error %d\n", r);

requeue:
    queue_delayed_work(zd_workqueue, &mac->housekeeping.link_led_work,
                   LINK_LED_WORK_DELAY);
}

static void housekeeping_init(struct zd_mac *mac)
{
    INIT_DELAYED_WORK(&mac->housekeeping.link_led_work, link_led_handler);
}

static void housekeeping_enable(struct zd_mac *mac)
{
    dev_dbg_f(zd_mac_dev(mac), "\n");
    queue_delayed_work(zd_workqueue, &mac->housekeeping.link_led_work,
               0);
}

static void housekeeping_disable(struct zd_mac *mac)
{
    dev_dbg_f(zd_mac_dev(mac), "\n");
    cancel_delayed_work_sync(&mac->housekeeping.link_led_work);
    zd_chip_control_leds(&mac->chip, ZD_LED_OFF);
}