// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
 *
 * Copyright(c) 2008 - 2014 Intel Corporation. All rights reserved.
 * Copyright(c) 2018        Intel Corporation
 *
 * Contact Information:
 *  Intel Linux Wireless <linuxwifi@intel.com>
 * 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_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)
{
        struct cfg80211_scan_info info = {
                .aborted = 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, &info);
        }

        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_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");
}

/*
 * iwl_scan_cancel - Cancel any currently executing HW scan
 */
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;
}

/*
 * iwl_scan_cancel_timeout - Cancel any currently executing HW scan
 * @ms: amount of time to wait (in milliseconds) for scan to abort
 */
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 void iwl_rx_reply_scan(struct iwl_priv *priv,
                              struct iwl_rx_cmd_buffer *rxb)
{
#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
}

/* Service SCAN_START_NOTIFICATION (0x82) */
static void iwl_rx_scan_start_notif(struct iwl_priv *priv,
                                    struct iwl_rx_cmd_buffer *rxb)
{
        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);
}

/* Service SCAN_RESULTS_NOTIFICATION (0x83) */
static void iwl_rx_scan_results_notif(struct iwl_priv *priv,
                                      struct iwl_rx_cmd_buffer *rxb)
{
#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
}

/* Service SCAN_COMPLETE_NOTIFICATION (0x84) */
static void iwl_rx_scan_complete_notif(struct iwl_priv *priv,
                                       struct iwl_rx_cmd_buffer *rxb)
{
        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 == NL80211_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);
        }
}

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 nl80211_band band, u8 n_probes)
{
        if (band == NL80211_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 */
        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 nl80211_band band)
{
        u16 passive = (band == NL80211_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 nl80211_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 nl80211_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 == NL80211_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 nl80211_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_NO_IR))
                        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 == NL80211_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;
}

/*
 * iwl_fill_probe_req - fill in all required fields and IE for probe request
 */
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), },
        };
        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 nl80211_band band;
        u8 n_probes = 0;
        u8 rx_ant = priv->nvm_data->valid_rx_ant;
        u8 rate;
        bool is_active = false;
        int  chan_mod;
        u8 active_chains;
        u8 scan_tx_antennas = priv->nvm_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(priv->scan_type == IWL_SCAN_NORMAL &&
                    (!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 (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_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);
        }

        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;
        }

        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 NL80211_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->lib->bt_params &&
                    priv->lib->bt_params->advanced_bt_coexist)
                        scan->tx_cmd.tx_flags |= TX_CMD_FLG_IGNORE_BT;
                break;
        case NL80211_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 == NL80211_BAND_2GHZ &&
            priv->lib->bt_params &&
            priv->lib->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->lib->bt_params &&
            priv->lib->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->nvm_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:
                /* 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;
        }

        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->nvm_data->valid_tx_ant) - 1;
        if (!priv->scan_tx_ant[NL80211_BAND_5GHZ])
                priv->scan_tx_ant[NL80211_BAND_5GHZ] = ant_idx;
        if (!priv->scan_tx_ant[NL80211_BAND_2GHZ])
                priv->scan_tx_ant[NL80211_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 nl80211_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 ? "" :
                        "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);
        }
}