text: /* ZD1211 USB-WLAN driver for Linux
   *
   * Copyright (C) 2005-2007 Ulrich Kunitz <kune@deine-taler.de>
   * Copyright (C) 2006-2007 Daniel Drake <dsd@gentoo.org>
   * Copyright (C) 2006-2007 Michael Wu <flamingice@sourmilk.net>
   * Copyright (C) 2007-2008 Luis R. Rodriguez <mcgrof@winlab.rutgers.edu>
   *
   * 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, see <http://www.gnu.org/licenses/>.
   */
  
  #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;
  }
  
  /**
   * zd_mac_tx_status - reports tx status of a packet if required
   * @hw - a &struct ieee80211_hw pointer
   * @skb - a sk-buffer
   * @flags: extra flags to set in the TX status info
   * @ackssi: ACK signal strength
   * @success - True for successful transmission of the frame
   *
   * This information calls ieee80211_tx_status_irqsafe() if required by the
   * control information. It copies the control information into the status
   * information.
   *
   * If no status information has been requested, the skb is freed.
   */
  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);
  }
  
  /**
   * zd_mac_tx_failed - callback for failed frames
   * @dev: the mac80211 wireless device
   *
   * This function is called if a frame couldn't be successfully
   * transferred. The first frame from the tx queue, will be selected and
   * reported as error to the upper layers.
   */
  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(!ether_addr_equal(tx_hdr->addr1, tx_status->mac)))
  			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);
  }
  
  /**
   * zd_mac_tx_to_dev - callback for USB layer
   * @skb: a &sk_buff pointer
   * @error: error value, 0 if transmission successful
   *
   * Informs the MAC layer that the frame has successfully transferred to the
   * device. If an ACK is required and the transfer to the device has been
   * successful, the packets are put on the @ack_wait_queue with
   * the control set removed.
   */
  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 = 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;
  }
  
  /**
   * zd_op_tx - transmits a network frame to the device
   *
   * @dev: mac80211 hardware device
   * @skb: socket buffer
   * @control: the control structure
   *
   * This function transmit an IEEE 802.11 network frame to the device. The
   * control block of the skbuff will be initialized. If necessary the incoming
   * mac80211 queues will be stopped.
   */
  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);
  }
  
  /**
   * filter_ack - filters incoming packets for acknowledgements
   * @dev: the mac80211 device
   * @rx_hdr: received header
   * @stats: the status for the received packet
   *
   * This functions looks for ACK packets and tries to match them with the
   * frames in the tx queue. If a match is found the frame will be dequeued and
   * the upper layers is informed about the successful transmission. If
   * mac80211 queues have been stopped and the number of frames still to be
   * transmitted is low the queues will be opened again.
   *
   * Returns 1 if the frame was an ACK, 0 if it was ignored.
   */
  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(ether_addr_equal(tx_hdr->addr2, rx_hdr->addr1)))
  		{
  			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 = NL80211_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 ? */
  	skb_put_data(skb, 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->chandef.chan->hw_value;
  	spin_unlock_irq(&mac->lock);
  
  	return zd_chip_set_channel(&mac->chip, conf->chandef.chan->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_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_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[NL80211_BAND_2GHZ] = &mac->band;
  
  	ieee80211_hw_set(hw, MFP_CAPABLE);
  	ieee80211_hw_set(hw, HOST_BROADCAST_PS_BUFFERING);
  	ieee80211_hw_set(hw, RX_INCLUDES_FCS);
  	ieee80211_hw_set(hw, SIGNAL_UNSPEC);
  
  	hw->wiphy->interface_modes =
  		BIT(NL80211_IFTYPE_MESH_POINT) |
  		BIT(NL80211_IFTYPE_STATION) |
  		BIT(NL80211_IFTYPE_ADHOC) |
  		BIT(NL80211_IFTYPE_AP);
  
  	wiphy_ext_feature_set(hw->wiphy, NL80211_EXT_FEATURE_CQM_RSSI_LIST);
  
  	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);
  }
  