Save sram context after changing MPU, DSP or core clocks

[linux-ginger.git] / drivers / net / wireless / zd1211rw / zd_mac.c

/* 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, 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/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_ADD, "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 },
};

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 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;
}

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

static 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;
        r = zd_chip_switch_radio_on(chip);
        if (r < 0)
                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);
        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;
}

static 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;

        /* 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);
        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);
}

/**
 * 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 tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
                      int ackssi, bool success)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

        ieee80211_tx_info_clear_status(info);

        if (success)
                info->flags |= IEEE80211_TX_STAT_ACK;
        info->status.ack_signal = 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 succesfully be
 * 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 ieee80211_hw *hw)
{
        struct sk_buff_head *q = &zd_hw_mac(hw)->ack_wait_queue;
        struct sk_buff *skb;

        skb = skb_dequeue(q);
        if (skb == NULL)
                return;

        tx_status(hw, skb, 0, 0);
}

/**
 * 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];

        skb_pull(skb, sizeof(struct zd_ctrlset));
        if (unlikely(error ||
            (info->flags & IEEE80211_TX_CTL_NO_ACK))) {
                tx_status(hw, skb, 0, !error);
        } else {
                struct sk_buff_head *q =
                        &zd_hw_mac(hw)->ack_wait_queue;

                skb_queue_tail(q, skb);
                while (skb_queue_len(q) > ZD_MAC_MAX_ACK_WAITERS)
                        zd_mac_tx_failed(hw);
        }
}

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 int zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
{
        struct zd_mac *mac = zd_hw_mac(hw);
        int r;
        u32 tmp, j = 0;
        /* 4 more bytes for tail CRC */
        u32 full_len = beacon->len + 4;

        r = zd_iowrite32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, 0);
        if (r < 0)
                return r;
        r = zd_ioread32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, &tmp);
        if (r < 0)
                return r;

        while (tmp & 0x2) {
                r = zd_ioread32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, &tmp);
                if (r < 0)
                        return r;
                if ((++j % 100) == 0) {
                        printk(KERN_ERR "CR_BCN_FIFO_SEMAPHORE not ready\n");
                        if (j >= 500)  {
                                printk(KERN_ERR "Giving up beacon config.\n");
                                return -ETIMEDOUT;
                        }
                }
                msleep(1);
        }

        r = zd_iowrite32(&mac->chip, CR_BCN_FIFO, full_len - 1);
        if (r < 0)
                return r;
        if (zd_chip_is_zd1211b(&mac->chip)) {
                r = zd_iowrite32(&mac->chip, CR_BCN_LENGTH, full_len - 1);
                if (r < 0)
                        return r;
        }

        for (j = 0 ; j < beacon->len; j++) {
                r = zd_iowrite32(&mac->chip, CR_BCN_FIFO,
                                *((u8 *)(beacon->data + j)));
                if (r < 0)
                        return r;
        }

        for (j = 0; j < 4; j++) {
                r = zd_iowrite32(&mac->chip, CR_BCN_FIFO, 0x0);
                if (r < 0)
                        return r;
        }

        r = zd_iowrite32(&mac->chip, CR_BCN_FIFO_SEMAPHORE, 1);
        if (r < 0)
                return r;

        /* 802.11b/g 2.4G CCK 1Mb
         * 802.11a, not yet implemented, uses different values (see GPL vendor
         * driver)
         */
        return zd_iowrite32(&mac->chip, CR_BCN_PLCP_CFG, 0x00000400 |
                        (full_len << 19));
}

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);

        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 int zd_op_tx(struct ieee80211_hw *hw, 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 0;

fail:
        dev_kfree_skb(skb);
        return 0;
}

/**
 * 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 sk_buff *skb;
        struct sk_buff_head *q;
        unsigned long flags;

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

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

                tx_hdr = (struct ieee80211_hdr *)skb->data;
                if (likely(!memcmp(tx_hdr->addr2, rx_hdr->addr1, ETH_ALEN)))
                {
                        __skb_unlink(skb, q);
                        tx_status(hw, skb, stats->signal, 1);
                        goto out;
                }
        }
out:
        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 = status->signal_strength;
        stats.qual = zd_rx_qual_percent(buffer,
                                          length - sizeof(struct rx_status),
                                          status);

        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 the payload data is 4 byte aligned. */
                skb_reserve(skb, 2);
        }

        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_if_init_conf *conf)
{
        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 (conf->type) {
        case NL80211_IFTYPE_MONITOR:
        case NL80211_IFTYPE_MESH_POINT:
        case NL80211_IFTYPE_STATION:
        case NL80211_IFTYPE_ADHOC:
                mac->type = conf->type;
                break;
        default:
                return -EOPNOTSUPP;
        }

        return zd_write_mac_addr(&mac->chip, conf->mac_addr);
}

static void zd_op_remove_interface(struct ieee80211_hw *hw,
                                    struct ieee80211_if_init_conf *conf)
{
        struct zd_mac *mac = zd_hw_mac(hw);
        mac->type = NL80211_IFTYPE_UNSPECIFIED;
        zd_set_beacon_interval(&mac->chip, 0);
        zd_write_mac_addr(&mac->chip, NULL);
}

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;

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

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

        int_status = le16_to_cpu(*(__le16 *)(mac->intr_buffer+4));
        if (int_status & INT_CFG_NEXT_BCN)
                dev_dbg_f_limit(zd_mac_dev(mac), "INT_CFG_NEXT_BCN\n");
        else
                dev_dbg_f(zd_mac_dev(mac), "Unsupported interrupt\n");

        zd_chip_enable_hwint(&mac->chip);
}


static void set_multicast_hash_handler(struct work_struct *work)
{
        struct zd_mac *mac =
                container_of(work, struct zd_mac, set_multicast_hash_work);
        struct zd_mc_hash hash;

        spin_lock_irq(&mac->lock);
        hash = mac->multicast_hash;
        spin_unlock_irq(&mac->lock);

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

static void set_rx_filter_handler(struct work_struct *work)
{
        struct zd_mac *mac =
                container_of(work, struct zd_mac, set_rx_filter_work);
        int r;

        dev_dbg_f(zd_mac_dev(mac), "\n");
        r = set_rx_filter(mac);
        if (r)
                dev_err(zd_mac_dev(mac), "set_rx_filter_handler error %d\n", r);
}

static u64 zd_op_prepare_multicast(struct ieee80211_hw *hw,
                                   int mc_count, struct dev_addr_list *mclist)
{
        struct zd_mac *mac = zd_hw_mac(hw);
        struct zd_mc_hash hash;
        int i;

        zd_mc_clear(&hash);

        for (i = 0; i < mc_count; i++) {
                if (!mclist)
                        break;
                dev_dbg_f(zd_mac_dev(mac), "mc addr %pM\n", mclist->dmi_addr);
                zd_mc_add_addr(&hash, mclist->dmi_addr);
                mclist = mclist->next;
        }

        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;

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

        /* changed_flags is always populated but this driver
         * doesn't support all FIF flags so its possible we don't
         * need to do anything */
        if (!changed_flags)
                return;

        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);

        /* XXX: these can be called here now, can sleep now! */
        queue_work(zd_workqueue, &mac->set_multicast_hash_work);

        if (changed_flags & FIF_CONTROL)
                queue_work(zd_workqueue, &mac->set_rx_filter_work);

        /* 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_work(struct work_struct *work)
{
        struct zd_mac *mac =
                container_of(work, struct zd_mac, set_rts_cts_work);
        unsigned long flags;
        unsigned int short_preamble;

        mutex_lock(&mac->chip.mutex);

        spin_lock_irqsave(&mac->lock, flags);
        mac->updating_rts_rate = 0;
        short_preamble = mac->short_preamble;
        spin_unlock_irqrestore(&mac->lock, flags);

        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);
        unsigned long flags;
        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) {
                associated = true;
                if (changes & BSS_CHANGED_BEACON) {
                        struct sk_buff *beacon = ieee80211_beacon_get(hw, vif);

                        if (beacon) {
                                zd_mac_config_beacon(hw, beacon);
                                kfree_skb(beacon);
                        }
                }

                if (changes & BSS_CHANGED_BEACON_ENABLED) {
                        u32 interval;

                        if (bss_conf->enable_beacon)
                                interval = BCN_MODE_IBSS |
                                                bss_conf->beacon_int;
                        else
                                interval = 0;

                        zd_set_beacon_interval(&mac->chip, interval);
                }
        } 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_irqsave(&mac->lock, flags);
                mac->short_preamble = bss_conf->use_short_preamble;
                if (!mac->updating_rts_rate) {
                        mac->updating_rts_rate = 1;
                        /* FIXME: should disable TX here, until work has
                         * completed and RTS_CTS reg is updated */
                        queue_work(zd_workqueue, &mac->set_rts_cts_work);
                }
                spin_unlock_irqrestore(&mac->lock, flags);
        }
}

static u64 zd_op_get_tsf(struct ieee80211_hw *hw)
{
        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;

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

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

        skb_queue_head_init(&mac->ack_wait_queue);

        zd_chip_init(&mac->chip, hw, intf);
        housekeeping_init(mac);
        INIT_WORK(&mac->set_multicast_hash_work, set_multicast_hash_handler);
        INIT_WORK(&mac->set_rts_cts_work, set_rts_cts_work);
        INIT_WORK(&mac->set_rx_filter_work, set_rx_filter_handler);
        INIT_WORK(&mac->process_intr, zd_process_intr);

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

#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;

        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);

        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_rearming_delayed_workqueue(zd_workqueue,
                &mac->housekeeping.link_led_work);
        zd_chip_control_leds(&mac->chip, ZD_LED_OFF);
}