scan.c

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/******************************************************************************
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2008 - 2012 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110,
 * USA
 *
 * The full GNU General Public License is included in this distribution
 * in the file called LICENSE.GPL.
 *
 * Contact Information:
 *  Intel Linux Wireless <[email protected]>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *****************************************************************************/
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/etherdevice.h>
#include <net/mac80211.h>

#include "dev.h"
#include "agn.h"

/* For active scan, listen ACTIVE_DWELL_TIME (msec) on each channel after
 * sending probe req.  This should be set long enough to hear probe responses
 * from more than one AP.  */
#define IWL_ACTIVE_DWELL_TIME_24    (30)       /* all times in msec */
#define IWL_ACTIVE_DWELL_TIME_52    (20)

#define IWL_ACTIVE_DWELL_FACTOR_24GHZ (3)
#define IWL_ACTIVE_DWELL_FACTOR_52GHZ (2)

/* For passive scan, listen PASSIVE_DWELL_TIME (msec) on each channel.
 * Must be set longer than active dwell time.
 * For the most reliable scan, set > AP beacon interval (typically 100msec). */
#define IWL_PASSIVE_DWELL_TIME_24   (20)       /* all times in msec */
#define IWL_PASSIVE_DWELL_TIME_52   (10)
#define IWL_PASSIVE_DWELL_BASE      (100)
#define IWL_CHANNEL_TUNE_TIME       5
#define MAX_SCAN_CHANNEL        50

/* For reset radio, need minimal dwell time only */
#define IWL_RADIO_RESET_DWELL_TIME  5

static int iwl_send_scan_abort(struct iwl_priv *priv)
{
    int ret;
    struct iwl_host_cmd cmd = {
        .id = REPLY_SCAN_ABORT_CMD,
        .flags = CMD_SYNC | CMD_WANT_SKB,
    };
    __le32 *status;

    /* Exit instantly with error when device is not ready
     * to receive scan abort command or it does not perform
     * hardware scan currently */
    if (!test_bit(STATUS_READY, &priv->status) ||
        !test_bit(STATUS_SCAN_HW, &priv->status) ||
        test_bit(STATUS_FW_ERROR, &priv->status))
        return -EIO;

    ret = iwl_dvm_send_cmd(priv, &cmd);
    if (ret)
        return ret;

    status = (void *)cmd.resp_pkt->data;
    if (*status != CAN_ABORT_STATUS) {
        /* The scan abort will return 1 for success or
         * 2 for "failure".  A failure condition can be
         * due to simply not being in an active scan which
         * can occur if we send the scan abort before we
         * the microcode has notified us that a scan is
         * completed. */
        IWL_DEBUG_SCAN(priv, "SCAN_ABORT ret %d.\n",
                   le32_to_cpu(*status));
        ret = -EIO;
    }

    iwl_free_resp(&cmd);
    return ret;
}

static void iwl_complete_scan(struct iwl_priv *priv, bool aborted)
{
    /* check if scan was requested from mac80211 */
    if (priv->scan_request) {
        IWL_DEBUG_SCAN(priv, "Complete scan in mac80211\n");
        ieee80211_scan_completed(priv->hw, aborted);
    }

    if (priv->scan_type == IWL_SCAN_ROC)
        iwl_scan_roc_expired(priv);

    priv->scan_type = IWL_SCAN_NORMAL;
    priv->scan_vif = NULL;
    priv->scan_request = NULL;
}

static void iwl_process_scan_complete(struct iwl_priv *priv)
{
    bool aborted;

    lockdep_assert_held(&priv->mutex);

    if (!test_and_clear_bit(STATUS_SCAN_COMPLETE, &priv->status))
        return;

    IWL_DEBUG_SCAN(priv, "Completed scan.\n");

    cancel_delayed_work(&priv->scan_check);

    aborted = test_and_clear_bit(STATUS_SCAN_ABORTING, &priv->status);
    if (aborted)
        IWL_DEBUG_SCAN(priv, "Aborted scan completed.\n");

    if (!test_and_clear_bit(STATUS_SCANNING, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "Scan already completed.\n");
        goto out_settings;
    }

    if (priv->scan_type == IWL_SCAN_ROC)
        iwl_scan_roc_expired(priv);

    if (priv->scan_type != IWL_SCAN_NORMAL && !aborted) {
        int err;

        /* Check if mac80211 requested scan during our internal scan */
        if (priv->scan_request == NULL)
            goto out_complete;

        /* If so request a new scan */
        err = iwl_scan_initiate(priv, priv->scan_vif, IWL_SCAN_NORMAL,
                    priv->scan_request->channels[0]->band);
        if (err) {
            IWL_DEBUG_SCAN(priv,
                "failed to initiate pending scan: %d\n", err);
            aborted = true;
            goto out_complete;
        }

        return;
    }

out_complete:
    iwl_complete_scan(priv, aborted);

out_settings:
    /* Can we still talk to firmware ? */
    if (!iwl_is_ready_rf(priv))
        return;

    iwlagn_post_scan(priv);
}

void iwl_force_scan_end(struct iwl_priv *priv)
{
    lockdep_assert_held(&priv->mutex);

    if (!test_bit(STATUS_SCANNING, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "Forcing scan end while not scanning\n");
        return;
    }

    IWL_DEBUG_SCAN(priv, "Forcing scan end\n");
    clear_bit(STATUS_SCANNING, &priv->status);
    clear_bit(STATUS_SCAN_HW, &priv->status);
    clear_bit(STATUS_SCAN_ABORTING, &priv->status);
    clear_bit(STATUS_SCAN_COMPLETE, &priv->status);
    iwl_complete_scan(priv, true);
}

static void iwl_do_scan_abort(struct iwl_priv *priv)
{
    int ret;

    lockdep_assert_held(&priv->mutex);

    if (!test_bit(STATUS_SCANNING, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "Not performing scan to abort\n");
        return;
    }

    if (test_and_set_bit(STATUS_SCAN_ABORTING, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "Scan abort in progress\n");
        return;
    }

    ret = iwl_send_scan_abort(priv);
    if (ret) {
        IWL_DEBUG_SCAN(priv, "Send scan abort failed %d\n", ret);
        iwl_force_scan_end(priv);
    } else
        IWL_DEBUG_SCAN(priv, "Successfully send scan abort\n");
}

int iwl_scan_cancel(struct iwl_priv *priv)
{
    IWL_DEBUG_SCAN(priv, "Queuing abort scan\n");
    queue_work(priv->workqueue, &priv->abort_scan);
    return 0;
}

void iwl_scan_cancel_timeout(struct iwl_priv *priv, unsigned long ms)
{
    unsigned long timeout = jiffies + msecs_to_jiffies(ms);

    lockdep_assert_held(&priv->mutex);

    IWL_DEBUG_SCAN(priv, "Scan cancel timeout\n");

    iwl_do_scan_abort(priv);

    while (time_before_eq(jiffies, timeout)) {
        if (!test_bit(STATUS_SCAN_HW, &priv->status))
            goto finished;
        msleep(20);
    }

    return;

 finished:
    /*
     * Now STATUS_SCAN_HW is clear. This means that the
     * device finished, but the background work is going
     * to execute at best as soon as we release the mutex.
     * Since we need to be able to issue a new scan right
     * after this function returns, run the complete here.
     * The STATUS_SCAN_COMPLETE bit will then be cleared
     * and prevent the background work from "completing"
     * a possible new scan.
     */
    iwl_process_scan_complete(priv);
}

/* Service response to REPLY_SCAN_CMD (0x80) */
static int iwl_rx_reply_scan(struct iwl_priv *priv,
                  struct iwl_rx_cmd_buffer *rxb,
                  struct iwl_device_cmd *cmd)
{
#ifdef CONFIG_IWLWIFI_DEBUG
    struct iwl_rx_packet *pkt = rxb_addr(rxb);
    struct iwl_scanreq_notification *notif = (void *)pkt->data;

    IWL_DEBUG_SCAN(priv, "Scan request status = 0x%x\n", notif->status);
#endif
    return 0;
}

/* Service SCAN_START_NOTIFICATION (0x82) */
static int iwl_rx_scan_start_notif(struct iwl_priv *priv,
                    struct iwl_rx_cmd_buffer *rxb,
                    struct iwl_device_cmd *cmd)
{
    struct iwl_rx_packet *pkt = rxb_addr(rxb);
    struct iwl_scanstart_notification *notif = (void *)pkt->data;

    priv->scan_start_tsf = le32_to_cpu(notif->tsf_low);
    IWL_DEBUG_SCAN(priv, "Scan start: "
               "%d [802.11%s] "
               "(TSF: 0x%08X:%08X) - %d (beacon timer %u)\n",
               notif->channel,
               notif->band ? "bg" : "a",
               le32_to_cpu(notif->tsf_high),
               le32_to_cpu(notif->tsf_low),
               notif->status, notif->beacon_timer);

    if (priv->scan_type == IWL_SCAN_ROC &&
        !priv->hw_roc_start_notified) {
        ieee80211_ready_on_channel(priv->hw);
        priv->hw_roc_start_notified = true;
    }

    return 0;
}

/* Service SCAN_RESULTS_NOTIFICATION (0x83) */
static int iwl_rx_scan_results_notif(struct iwl_priv *priv,
                      struct iwl_rx_cmd_buffer *rxb,
                      struct iwl_device_cmd *cmd)
{
#ifdef CONFIG_IWLWIFI_DEBUG
    struct iwl_rx_packet *pkt = rxb_addr(rxb);
    struct iwl_scanresults_notification *notif = (void *)pkt->data;

    IWL_DEBUG_SCAN(priv, "Scan ch.res: "
               "%d [802.11%s] "
               "probe status: %u:%u "
               "(TSF: 0x%08X:%08X) - %d "
               "elapsed=%lu usec\n",
               notif->channel,
               notif->band ? "bg" : "a",
               notif->probe_status, notif->num_probe_not_sent,
               le32_to_cpu(notif->tsf_high),
               le32_to_cpu(notif->tsf_low),
               le32_to_cpu(notif->statistics[0]),
               le32_to_cpu(notif->tsf_low) - priv->scan_start_tsf);
#endif
    return 0;
}

/* Service SCAN_COMPLETE_NOTIFICATION (0x84) */
static int iwl_rx_scan_complete_notif(struct iwl_priv *priv,
                       struct iwl_rx_cmd_buffer *rxb,
                       struct iwl_device_cmd *cmd)
{
    struct iwl_rx_packet *pkt = rxb_addr(rxb);
    struct iwl_scancomplete_notification *scan_notif = (void *)pkt->data;

    IWL_DEBUG_SCAN(priv, "Scan complete: %d channels (TSF 0x%08X:%08X) - %d\n",
               scan_notif->scanned_channels,
               scan_notif->tsf_low,
               scan_notif->tsf_high, scan_notif->status);

    IWL_DEBUG_SCAN(priv, "Scan on %sGHz took %dms\n",
               (priv->scan_band == IEEE80211_BAND_2GHZ) ? "2.4" : "5.2",
               jiffies_to_msecs(jiffies - priv->scan_start));

    /*
     * When aborting, we run the scan completed background work inline
     * and the background work must then do nothing. The SCAN_COMPLETE
     * bit helps implement that logic and thus needs to be set before
     * queueing the work. Also, since the scan abort waits for SCAN_HW
     * to clear, we need to set SCAN_COMPLETE before clearing SCAN_HW
     * to avoid a race there.
     */
    set_bit(STATUS_SCAN_COMPLETE, &priv->status);
    clear_bit(STATUS_SCAN_HW, &priv->status);
    queue_work(priv->workqueue, &priv->scan_completed);

    if (priv->iw_mode != NL80211_IFTYPE_ADHOC &&
        iwl_advanced_bt_coexist(priv) &&
        priv->bt_status != scan_notif->bt_status) {
        if (scan_notif->bt_status) {
            /* BT on */
            if (!priv->bt_ch_announce)
                priv->bt_traffic_load =
                    IWL_BT_COEX_TRAFFIC_LOAD_HIGH;
            /*
             * otherwise, no traffic load information provided
             * no changes made
             */
        } else {
            /* BT off */
            priv->bt_traffic_load =
                IWL_BT_COEX_TRAFFIC_LOAD_NONE;
        }
        priv->bt_status = scan_notif->bt_status;
        queue_work(priv->workqueue,
               &priv->bt_traffic_change_work);
    }
    return 0;
}

void iwl_setup_rx_scan_handlers(struct iwl_priv *priv)
{
    /* scan handlers */
    priv->rx_handlers[REPLY_SCAN_CMD] = iwl_rx_reply_scan;
    priv->rx_handlers[SCAN_START_NOTIFICATION] = iwl_rx_scan_start_notif;
    priv->rx_handlers[SCAN_RESULTS_NOTIFICATION] =
                    iwl_rx_scan_results_notif;
    priv->rx_handlers[SCAN_COMPLETE_NOTIFICATION] =
                    iwl_rx_scan_complete_notif;
}

static u16 iwl_get_active_dwell_time(struct iwl_priv *priv,
                     enum ieee80211_band band, u8 n_probes)
{
    if (band == IEEE80211_BAND_5GHZ)
        return IWL_ACTIVE_DWELL_TIME_52 +
            IWL_ACTIVE_DWELL_FACTOR_52GHZ * (n_probes + 1);
    else
        return IWL_ACTIVE_DWELL_TIME_24 +
            IWL_ACTIVE_DWELL_FACTOR_24GHZ * (n_probes + 1);
}

static u16 iwl_limit_dwell(struct iwl_priv *priv, u16 dwell_time)
{
    struct iwl_rxon_context *ctx;
    int limits[NUM_IWL_RXON_CTX] = {};
    int n_active = 0;
    u16 limit;

    BUILD_BUG_ON(NUM_IWL_RXON_CTX != 2);

    /*
     * If we're associated, we clamp the dwell time 98%
     * of the beacon interval (minus 2 * channel tune time)
     * If both contexts are active, we have to restrict to
     * 1/2 of the minimum of them, because they might be in
     * lock-step with the time inbetween only half of what
     * time we'd have in each of them.
     */
    for_each_context(priv, ctx) {
        switch (ctx->staging.dev_type) {
        case RXON_DEV_TYPE_P2P:
            /* no timing constraints */
            continue;
        case RXON_DEV_TYPE_ESS:
        default:
            /* timing constraints if associated */
            if (!iwl_is_associated_ctx(ctx))
                continue;
            break;
        case RXON_DEV_TYPE_CP:
        case RXON_DEV_TYPE_2STA:
            /*
             * These seem to always have timers for TBTT
             * active in uCode even when not associated yet.
             */
            break;
        }

        limits[n_active++] = ctx->beacon_int ?: IWL_PASSIVE_DWELL_BASE;
    }

    switch (n_active) {
    case 0:
        return dwell_time;
    case 2:
        limit = (limits[1] * 98) / 100 - IWL_CHANNEL_TUNE_TIME * 2;
        limit /= 2;
        dwell_time = min(limit, dwell_time);
        /* fall through to limit further */
    case 1:
        limit = (limits[0] * 98) / 100 - IWL_CHANNEL_TUNE_TIME * 2;
        limit /= n_active;
        return min(limit, dwell_time);
    default:
        WARN_ON_ONCE(1);
        return dwell_time;
    }
}

static u16 iwl_get_passive_dwell_time(struct iwl_priv *priv,
                      enum ieee80211_band band)
{
    u16 passive = (band == IEEE80211_BAND_2GHZ) ?
        IWL_PASSIVE_DWELL_BASE + IWL_PASSIVE_DWELL_TIME_24 :
        IWL_PASSIVE_DWELL_BASE + IWL_PASSIVE_DWELL_TIME_52;

    return iwl_limit_dwell(priv, passive);
}

/* Return valid, unused, channel for a passive scan to reset the RF */
static u8 iwl_get_single_channel_number(struct iwl_priv *priv,
                    enum ieee80211_band band)
{
    struct ieee80211_supported_band *sband = priv->hw->wiphy->bands[band];
    struct iwl_rxon_context *ctx;
    int i;

    for (i = 0; i < sband->n_channels; i++) {
        bool busy = false;

        for_each_context(priv, ctx) {
            busy = sband->channels[i].hw_value ==
                le16_to_cpu(ctx->staging.channel);
            if (busy)
                break;
        }

        if (busy)
            continue;

        if (!(sband->channels[i].flags & IEEE80211_CHAN_DISABLED))
            return sband->channels[i].hw_value;
    }

    return 0;
}

static int iwl_get_channel_for_reset_scan(struct iwl_priv *priv,
                      struct ieee80211_vif *vif,
                      enum ieee80211_band band,
                      struct iwl_scan_channel *scan_ch)
{
    const struct ieee80211_supported_band *sband;
    u16 channel;

    sband = iwl_get_hw_mode(priv, band);
    if (!sband) {
        IWL_ERR(priv, "invalid band\n");
        return 0;
    }

    channel = iwl_get_single_channel_number(priv, band);
    if (channel) {
        scan_ch->channel = cpu_to_le16(channel);
        scan_ch->type = SCAN_CHANNEL_TYPE_PASSIVE;
        scan_ch->active_dwell =
            cpu_to_le16(IWL_RADIO_RESET_DWELL_TIME);
        scan_ch->passive_dwell =
            cpu_to_le16(IWL_RADIO_RESET_DWELL_TIME);
        /* Set txpower levels to defaults */
        scan_ch->dsp_atten = 110;
        if (band == IEEE80211_BAND_5GHZ)
            scan_ch->tx_gain = ((1 << 5) | (3 << 3)) | 3;
        else
            scan_ch->tx_gain = ((1 << 5) | (5 << 3));
        return 1;
    }

    IWL_ERR(priv, "no valid channel found\n");
    return 0;
}

static int iwl_get_channels_for_scan(struct iwl_priv *priv,
                     struct ieee80211_vif *vif,
                     enum ieee80211_band band,
                     u8 is_active, u8 n_probes,
                     struct iwl_scan_channel *scan_ch)
{
    struct ieee80211_channel *chan;
    const struct ieee80211_supported_band *sband;
    u16 passive_dwell = 0;
    u16 active_dwell = 0;
    int added, i;
    u16 channel;

    sband = iwl_get_hw_mode(priv, band);
    if (!sband)
        return 0;

    active_dwell = iwl_get_active_dwell_time(priv, band, n_probes);
    passive_dwell = iwl_get_passive_dwell_time(priv, band);

    if (passive_dwell <= active_dwell)
        passive_dwell = active_dwell + 1;

    for (i = 0, added = 0; i < priv->scan_request->n_channels; i++) {
        chan = priv->scan_request->channels[i];

        if (chan->band != band)
            continue;

        channel = chan->hw_value;
        scan_ch->channel = cpu_to_le16(channel);

        if (!is_active || (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN))
            scan_ch->type = SCAN_CHANNEL_TYPE_PASSIVE;
        else
            scan_ch->type = SCAN_CHANNEL_TYPE_ACTIVE;

        if (n_probes)
            scan_ch->type |= IWL_SCAN_PROBE_MASK(n_probes);

        scan_ch->active_dwell = cpu_to_le16(active_dwell);
        scan_ch->passive_dwell = cpu_to_le16(passive_dwell);

        /* Set txpower levels to defaults */
        scan_ch->dsp_atten = 110;

        /* NOTE: if we were doing 6Mb OFDM for scans we'd use
         * power level:
         * scan_ch->tx_gain = ((1 << 5) | (2 << 3)) | 3;
         */
        if (band == IEEE80211_BAND_5GHZ)
            scan_ch->tx_gain = ((1 << 5) | (3 << 3)) | 3;
        else
            scan_ch->tx_gain = ((1 << 5) | (5 << 3));

        IWL_DEBUG_SCAN(priv, "Scanning ch=%d prob=0x%X [%s %d]\n",
                   channel, le32_to_cpu(scan_ch->type),
                   (scan_ch->type & SCAN_CHANNEL_TYPE_ACTIVE) ?
                "ACTIVE" : "PASSIVE",
                   (scan_ch->type & SCAN_CHANNEL_TYPE_ACTIVE) ?
                   active_dwell : passive_dwell);

        scan_ch++;
        added++;
    }

    IWL_DEBUG_SCAN(priv, "total channels to scan %d\n", added);
    return added;
}

static u16 iwl_fill_probe_req(struct ieee80211_mgmt *frame, const u8 *ta,
                  const u8 *ies, int ie_len, const u8 *ssid,
                  u8 ssid_len, int left)
{
    int len = 0;
    u8 *pos = NULL;

    /* Make sure there is enough space for the probe request,
     * two mandatory IEs and the data */
    left -= 24;
    if (left < 0)
        return 0;

    frame->frame_control = cpu_to_le16(IEEE80211_STYPE_PROBE_REQ);
    eth_broadcast_addr(frame->da);
    memcpy(frame->sa, ta, ETH_ALEN);
    eth_broadcast_addr(frame->bssid);
    frame->seq_ctrl = 0;

    len += 24;

    /* ...next IE... */
    pos = &frame->u.probe_req.variable[0];

    /* fill in our SSID IE */
    left -= ssid_len + 2;
    if (left < 0)
        return 0;
    *pos++ = WLAN_EID_SSID;
    *pos++ = ssid_len;
    if (ssid && ssid_len) {
        memcpy(pos, ssid, ssid_len);
        pos += ssid_len;
    }

    len += ssid_len + 2;

    if (WARN_ON(left < ie_len))
        return len;

    if (ies && ie_len) {
        memcpy(pos, ies, ie_len);
        len += ie_len;
    }

    return (u16)len;
}

static int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
{
    struct iwl_host_cmd cmd = {
        .id = REPLY_SCAN_CMD,
        .len = { sizeof(struct iwl_scan_cmd), },
        .flags = CMD_SYNC,
    };
    struct iwl_scan_cmd *scan;
    struct iwl_rxon_context *ctx = &priv->contexts[IWL_RXON_CTX_BSS];
    u32 rate_flags = 0;
    u16 cmd_len = 0;
    u16 rx_chain = 0;
    enum ieee80211_band band;
    u8 n_probes = 0;
    u8 rx_ant = priv->eeprom_data->valid_rx_ant;
    u8 rate;
    bool is_active = false;
    int  chan_mod;
    u8 active_chains;
    u8 scan_tx_antennas = priv->eeprom_data->valid_tx_ant;
    int ret;
    int scan_cmd_size = sizeof(struct iwl_scan_cmd) +
                MAX_SCAN_CHANNEL * sizeof(struct iwl_scan_channel) +
                priv->fw->ucode_capa.max_probe_length;
    const u8 *ssid = NULL;
    u8 ssid_len = 0;

    if (WARN_ON_ONCE(priv->scan_request &&
             priv->scan_request->n_channels > MAX_SCAN_CHANNEL))
        return -EINVAL;

    lockdep_assert_held(&priv->mutex);

    if (vif)
        ctx = iwl_rxon_ctx_from_vif(vif);

    if (!priv->scan_cmd) {
        priv->scan_cmd = kmalloc(scan_cmd_size, GFP_KERNEL);
        if (!priv->scan_cmd) {
            IWL_DEBUG_SCAN(priv,
                       "fail to allocate memory for scan\n");
            return -ENOMEM;
        }
    }
    scan = priv->scan_cmd;
    memset(scan, 0, scan_cmd_size);

    scan->quiet_plcp_th = IWL_PLCP_QUIET_THRESH;
    scan->quiet_time = IWL_ACTIVE_QUIET_TIME;

    if (priv->scan_type != IWL_SCAN_ROC &&
        iwl_is_any_associated(priv)) {
        u16 interval = 0;
        u32 extra;
        u32 suspend_time = 100;
        u32 scan_suspend_time = 100;

        IWL_DEBUG_INFO(priv, "Scanning while associated...\n");
        switch (priv->scan_type) {
        case IWL_SCAN_ROC:
            WARN_ON(1);
            break;
        case IWL_SCAN_RADIO_RESET:
            interval = 0;
            break;
        case IWL_SCAN_NORMAL:
            interval = vif->bss_conf.beacon_int;
            break;
        }

        scan->suspend_time = 0;
        scan->max_out_time = cpu_to_le32(200 * 1024);
        if (!interval)
            interval = suspend_time;

        extra = (suspend_time / interval) << 22;
        scan_suspend_time = (extra |
            ((suspend_time % interval) * 1024));
        scan->suspend_time = cpu_to_le32(scan_suspend_time);
        IWL_DEBUG_SCAN(priv, "suspend_time 0x%X beacon interval %d\n",
                   scan_suspend_time, interval);
    } else if (priv->scan_type == IWL_SCAN_ROC) {
        scan->suspend_time = 0;
        scan->max_out_time = 0;
        scan->quiet_time = 0;
        scan->quiet_plcp_th = 0;
    }

    switch (priv->scan_type) {
    case IWL_SCAN_RADIO_RESET:
        IWL_DEBUG_SCAN(priv, "Start internal passive scan.\n");
        /*
         * Override quiet time as firmware checks that active
         * dwell is >= quiet; since we use passive scan it'll
         * not actually be used.
         */
        scan->quiet_time = cpu_to_le16(IWL_RADIO_RESET_DWELL_TIME);
        break;
    case IWL_SCAN_NORMAL:
        if (priv->scan_request->n_ssids) {
            int i, p = 0;
            IWL_DEBUG_SCAN(priv, "Kicking off active scan\n");
            /*
             * The highest priority SSID is inserted to the
             * probe request template.
             */
            ssid_len = priv->scan_request->ssids[0].ssid_len;
            ssid = priv->scan_request->ssids[0].ssid;

            /*
             * Invert the order of ssids, the firmware will invert
             * it back.
             */
            for (i = priv->scan_request->n_ssids - 1; i >= 1; i--) {
                scan->direct_scan[p].id = WLAN_EID_SSID;
                scan->direct_scan[p].len =
                    priv->scan_request->ssids[i].ssid_len;
                memcpy(scan->direct_scan[p].ssid,
                       priv->scan_request->ssids[i].ssid,
                       priv->scan_request->ssids[i].ssid_len);
                n_probes++;
                p++;
            }
            is_active = true;
        } else
            IWL_DEBUG_SCAN(priv, "Start passive scan.\n");
        break;
    case IWL_SCAN_ROC:
        IWL_DEBUG_SCAN(priv, "Start ROC scan.\n");
        break;
    }

    scan->tx_cmd.tx_flags = TX_CMD_FLG_SEQ_CTL_MSK;
    scan->tx_cmd.sta_id = ctx->bcast_sta_id;
    scan->tx_cmd.stop_time.life_time = TX_CMD_LIFE_TIME_INFINITE;

    switch (priv->scan_band) {
    case IEEE80211_BAND_2GHZ:
        scan->flags = RXON_FLG_BAND_24G_MSK | RXON_FLG_AUTO_DETECT_MSK;
        chan_mod = le32_to_cpu(
            priv->contexts[IWL_RXON_CTX_BSS].active.flags &
                        RXON_FLG_CHANNEL_MODE_MSK)
                       >> RXON_FLG_CHANNEL_MODE_POS;
        if ((priv->scan_request && priv->scan_request->no_cck) ||
            chan_mod == CHANNEL_MODE_PURE_40) {
            rate = IWL_RATE_6M_PLCP;
        } else {
            rate = IWL_RATE_1M_PLCP;
            rate_flags = RATE_MCS_CCK_MSK;
        }
        /*
         * Internal scans are passive, so we can indiscriminately set
         * the BT ignore flag on 2.4 GHz since it applies to TX only.
         */
        if (priv->cfg->bt_params &&
            priv->cfg->bt_params->advanced_bt_coexist)
            scan->tx_cmd.tx_flags |= TX_CMD_FLG_IGNORE_BT;
        break;
    case IEEE80211_BAND_5GHZ:
        rate = IWL_RATE_6M_PLCP;
        break;
    default:
        IWL_WARN(priv, "Invalid scan band\n");
        return -EIO;
    }

    /*
     * If active scanning is requested but a certain channel is
     * marked passive, we can do active scanning if we detect
     * transmissions.
     *
     * There is an issue with some firmware versions that triggers
     * a sysassert on a "good CRC threshold" of zero (== disabled),
     * on a radar channel even though this means that we should NOT
     * send probes.
     *
     * The "good CRC threshold" is the number of frames that we
     * need to receive during our dwell time on a channel before
     * sending out probes -- setting this to a huge value will
     * mean we never reach it, but at the same time work around
     * the aforementioned issue. Thus use IWL_GOOD_CRC_TH_NEVER
     * here instead of IWL_GOOD_CRC_TH_DISABLED.
     *
     * This was fixed in later versions along with some other
     * scan changes, and the threshold behaves as a flag in those
     * versions.
     */
    if (priv->new_scan_threshold_behaviour)
        scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH_DEFAULT :
                        IWL_GOOD_CRC_TH_DISABLED;
    else
        scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH_DEFAULT :
                        IWL_GOOD_CRC_TH_NEVER;

    band = priv->scan_band;

    if (band == IEEE80211_BAND_2GHZ &&
        priv->cfg->bt_params &&
        priv->cfg->bt_params->advanced_bt_coexist) {
        /* transmit 2.4 GHz probes only on first antenna */
        scan_tx_antennas = first_antenna(scan_tx_antennas);
    }

    priv->scan_tx_ant[band] = iwl_toggle_tx_ant(priv,
                            priv->scan_tx_ant[band],
                            scan_tx_antennas);
    rate_flags |= iwl_ant_idx_to_flags(priv->scan_tx_ant[band]);
    scan->tx_cmd.rate_n_flags = iwl_hw_set_rate_n_flags(rate, rate_flags);

    /*
     * In power save mode while associated use one chain,
     * otherwise use all chains
     */
    if (test_bit(STATUS_POWER_PMI, &priv->status) &&
        !(priv->hw->conf.flags & IEEE80211_CONF_IDLE)) {
        /* rx_ant has been set to all valid chains previously */
        active_chains = rx_ant &
                ((u8)(priv->chain_noise_data.active_chains));
        if (!active_chains)
            active_chains = rx_ant;

        IWL_DEBUG_SCAN(priv, "chain_noise_data.active_chains: %u\n",
                priv->chain_noise_data.active_chains);

        rx_ant = first_antenna(active_chains);
    }
    if (priv->cfg->bt_params &&
        priv->cfg->bt_params->advanced_bt_coexist &&
        priv->bt_full_concurrent) {
        /* operated as 1x1 in full concurrency mode */
        rx_ant = first_antenna(rx_ant);
    }

    /* MIMO is not used here, but value is required */
    rx_chain |=
        priv->eeprom_data->valid_rx_ant << RXON_RX_CHAIN_VALID_POS;
    rx_chain |= rx_ant << RXON_RX_CHAIN_FORCE_MIMO_SEL_POS;
    rx_chain |= rx_ant << RXON_RX_CHAIN_FORCE_SEL_POS;
    rx_chain |= 0x1 << RXON_RX_CHAIN_DRIVER_FORCE_POS;
    scan->rx_chain = cpu_to_le16(rx_chain);
    switch (priv->scan_type) {
    case IWL_SCAN_NORMAL:
        cmd_len = iwl_fill_probe_req(
                    (struct ieee80211_mgmt *)scan->data,
                    vif->addr,
                    priv->scan_request->ie,
                    priv->scan_request->ie_len,
                    ssid, ssid_len,
                    scan_cmd_size - sizeof(*scan));
        break;
    case IWL_SCAN_RADIO_RESET:
    case IWL_SCAN_ROC:
        /* use bcast addr, will not be transmitted but must be valid */
        cmd_len = iwl_fill_probe_req(
                    (struct ieee80211_mgmt *)scan->data,
                    iwl_bcast_addr, NULL, 0,
                    NULL, 0,
                    scan_cmd_size - sizeof(*scan));
        break;
    default:
        BUG();
    }
    scan->tx_cmd.len = cpu_to_le16(cmd_len);

    scan->filter_flags |= (RXON_FILTER_ACCEPT_GRP_MSK |
                   RXON_FILTER_BCON_AWARE_MSK);

    switch (priv->scan_type) {
    case IWL_SCAN_RADIO_RESET:
        scan->channel_count =
            iwl_get_channel_for_reset_scan(priv, vif, band,
                (void *)&scan->data[cmd_len]);
        break;
    case IWL_SCAN_NORMAL:
        scan->channel_count =
            iwl_get_channels_for_scan(priv, vif, band,
                is_active, n_probes,
                (void *)&scan->data[cmd_len]);
        break;
    case IWL_SCAN_ROC: {
        struct iwl_scan_channel *scan_ch;
        int n_chan, i;
        u16 dwell;

        dwell = iwl_limit_dwell(priv, priv->hw_roc_duration);
        n_chan = DIV_ROUND_UP(priv->hw_roc_duration, dwell);

        scan->channel_count = n_chan;

        scan_ch = (void *)&scan->data[cmd_len];

        for (i = 0; i < n_chan; i++) {
            scan_ch->type = SCAN_CHANNEL_TYPE_PASSIVE;
            scan_ch->channel =
                cpu_to_le16(priv->hw_roc_channel->hw_value);

            if (i == n_chan - 1)
                dwell = priv->hw_roc_duration - i * dwell;

            scan_ch->active_dwell =
            scan_ch->passive_dwell = cpu_to_le16(dwell);

            /* Set txpower levels to defaults */
            scan_ch->dsp_atten = 110;

            /* NOTE: if we were doing 6Mb OFDM for scans we'd use
             * power level:
             * scan_ch->tx_gain = ((1 << 5) | (2 << 3)) | 3;
             */
            if (priv->hw_roc_channel->band == IEEE80211_BAND_5GHZ)
                scan_ch->tx_gain = ((1 << 5) | (3 << 3)) | 3;
            else
                scan_ch->tx_gain = ((1 << 5) | (5 << 3));

            scan_ch++;
        }
        }

        break;
    }

    if (scan->channel_count == 0) {
        IWL_DEBUG_SCAN(priv, "channel count %d\n", scan->channel_count);
        return -EIO;
    }

    cmd.len[0] += le16_to_cpu(scan->tx_cmd.len) +
        scan->channel_count * sizeof(struct iwl_scan_channel);
    cmd.data[0] = scan;
    cmd.dataflags[0] = IWL_HCMD_DFL_NOCOPY;
    scan->len = cpu_to_le16(cmd.len[0]);

    /* set scan bit here for PAN params */
    set_bit(STATUS_SCAN_HW, &priv->status);

    ret = iwlagn_set_pan_params(priv);
    if (ret) {
        clear_bit(STATUS_SCAN_HW, &priv->status);
        return ret;
    }

    ret = iwl_dvm_send_cmd(priv, &cmd);
    if (ret) {
        clear_bit(STATUS_SCAN_HW, &priv->status);
        iwlagn_set_pan_params(priv);
    }

    return ret;
}

void iwl_init_scan_params(struct iwl_priv *priv)
{
    u8 ant_idx = fls(priv->eeprom_data->valid_tx_ant) - 1;
    if (!priv->scan_tx_ant[IEEE80211_BAND_5GHZ])
        priv->scan_tx_ant[IEEE80211_BAND_5GHZ] = ant_idx;
    if (!priv->scan_tx_ant[IEEE80211_BAND_2GHZ])
        priv->scan_tx_ant[IEEE80211_BAND_2GHZ] = ant_idx;
}

int __must_check iwl_scan_initiate(struct iwl_priv *priv,
                   struct ieee80211_vif *vif,
                   enum iwl_scan_type scan_type,
                   enum ieee80211_band band)
{
    int ret;

    lockdep_assert_held(&priv->mutex);

    cancel_delayed_work(&priv->scan_check);

    if (!iwl_is_ready_rf(priv)) {
        IWL_WARN(priv, "Request scan called when driver not ready.\n");
        return -EIO;
    }

    if (test_bit(STATUS_SCAN_HW, &priv->status)) {
        IWL_DEBUG_SCAN(priv,
            "Multiple concurrent scan requests in parallel.\n");
        return -EBUSY;
    }

    if (test_bit(STATUS_SCAN_ABORTING, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "Scan request while abort pending.\n");
        return -EBUSY;
    }

    IWL_DEBUG_SCAN(priv, "Starting %sscan...\n",
            scan_type == IWL_SCAN_NORMAL ? "" :
            scan_type == IWL_SCAN_ROC ? "remain-on-channel " :
            "internal short ");

    set_bit(STATUS_SCANNING, &priv->status);
    priv->scan_type = scan_type;
    priv->scan_start = jiffies;
    priv->scan_band = band;

    ret = iwlagn_request_scan(priv, vif);
    if (ret) {
        clear_bit(STATUS_SCANNING, &priv->status);
        priv->scan_type = IWL_SCAN_NORMAL;
        return ret;
    }

    queue_delayed_work(priv->workqueue, &priv->scan_check,
               IWL_SCAN_CHECK_WATCHDOG);

    return 0;
}


/*
 * internal short scan, this function should only been called while associated.
 * It will reset and tune the radio to prevent possible RF related problem
 */
void iwl_internal_short_hw_scan(struct iwl_priv *priv)
{
    queue_work(priv->workqueue, &priv->start_internal_scan);
}

static void iwl_bg_start_internal_scan(struct work_struct *work)
{
    struct iwl_priv *priv =
        container_of(work, struct iwl_priv, start_internal_scan);

    IWL_DEBUG_SCAN(priv, "Start internal scan\n");

    mutex_lock(&priv->mutex);

    if (priv->scan_type == IWL_SCAN_RADIO_RESET) {
        IWL_DEBUG_SCAN(priv, "Internal scan already in progress\n");
        goto unlock;
    }

    if (test_bit(STATUS_SCANNING, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "Scan already in progress.\n");
        goto unlock;
    }

    if (iwl_scan_initiate(priv, NULL, IWL_SCAN_RADIO_RESET, priv->band))
        IWL_DEBUG_SCAN(priv, "failed to start internal short scan\n");
 unlock:
    mutex_unlock(&priv->mutex);
}

static void iwl_bg_scan_check(struct work_struct *data)
{
    struct iwl_priv *priv =
        container_of(data, struct iwl_priv, scan_check.work);

    IWL_DEBUG_SCAN(priv, "Scan check work\n");

    /* Since we are here firmware does not finish scan and
     * most likely is in bad shape, so we don't bother to
     * send abort command, just force scan complete to mac80211 */
    mutex_lock(&priv->mutex);
    iwl_force_scan_end(priv);
    mutex_unlock(&priv->mutex);
}

static void iwl_bg_abort_scan(struct work_struct *work)
{
    struct iwl_priv *priv = container_of(work, struct iwl_priv, abort_scan);

    IWL_DEBUG_SCAN(priv, "Abort scan work\n");

    /* We keep scan_check work queued in case when firmware will not
     * report back scan completed notification */
    mutex_lock(&priv->mutex);
    iwl_scan_cancel_timeout(priv, 200);
    mutex_unlock(&priv->mutex);
}

static void iwl_bg_scan_completed(struct work_struct *work)
{
    struct iwl_priv *priv =
        container_of(work, struct iwl_priv, scan_completed);

    mutex_lock(&priv->mutex);
    iwl_process_scan_complete(priv);
    mutex_unlock(&priv->mutex);
}

void iwl_setup_scan_deferred_work(struct iwl_priv *priv)
{
    INIT_WORK(&priv->scan_completed, iwl_bg_scan_completed);
    INIT_WORK(&priv->abort_scan, iwl_bg_abort_scan);
    INIT_WORK(&priv->start_internal_scan, iwl_bg_start_internal_scan);
    INIT_DELAYED_WORK(&priv->scan_check, iwl_bg_scan_check);
}

void iwl_cancel_scan_deferred_work(struct iwl_priv *priv)
{
    cancel_work_sync(&priv->start_internal_scan);
    cancel_work_sync(&priv->abort_scan);
    cancel_work_sync(&priv->scan_completed);

    if (cancel_delayed_work_sync(&priv->scan_check)) {
        mutex_lock(&priv->mutex);
        iwl_force_scan_end(priv);
        mutex_unlock(&priv->mutex);
    }
}

void iwl_scan_roc_expired(struct iwl_priv *priv)
{
    /*
     * The status bit should be set here, to prevent a race
     * where the atomic_read returns 1, but before the execution continues
     * iwl_scan_offchannel_skb_status() checks if the status bit is set
     */
    set_bit(STATUS_SCAN_ROC_EXPIRED, &priv->status);

    if (atomic_read(&priv->num_aux_in_flight) == 0) {
        ieee80211_remain_on_channel_expired(priv->hw);
        priv->hw_roc_channel = NULL;
        schedule_delayed_work(&priv->hw_roc_disable_work,
                      10 * HZ);

        clear_bit(STATUS_SCAN_ROC_EXPIRED, &priv->status);
    } else {
        IWL_DEBUG_SCAN(priv, "ROC done with %d frames in aux\n",
                   atomic_read(&priv->num_aux_in_flight));
    }
}

void iwl_scan_offchannel_skb(struct iwl_priv *priv)
{
    WARN_ON(!priv->hw_roc_start_notified);
    atomic_inc(&priv->num_aux_in_flight);
}

void iwl_scan_offchannel_skb_status(struct iwl_priv *priv)
{
    if (atomic_dec_return(&priv->num_aux_in_flight) == 0 &&
        test_bit(STATUS_SCAN_ROC_EXPIRED, &priv->status)) {
        IWL_DEBUG_SCAN(priv, "0 aux frames. Calling ROC expired\n");
        iwl_scan_roc_expired(priv);
    }
}