update madwifi

[linux-2.6/zen-sources.git] / drivers / net / wireless / madwifi / net80211 / ieee80211_scan.c

/*-
 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id: ieee80211_scan.c 3787 2008-07-17 04:50:29Z proski $
 */
#ifndef EXPORT_SYMTAB
#define EXPORT_SYMTAB
#endif

/*
 * IEEE 802.11 scanning support.
 */
#ifndef AUTOCONF_INCLUDED
#include <linux/config.h>
#endif
#include <linux/version.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/delay.h>

#include "if_media.h"

#include <net80211/ieee80211_var.h>
#include <net80211/if_athproto.h>

struct scan_state {
        struct ieee80211_scan_state base;       /* public state */

        u_int ss_iflags;                        /* flags used internally */
#define ISCAN_MINDWELL  0x0001                  /* min dwell time reached */
#define ISCAN_DISCARD   0x0002                  /* discard rx'd frames */
#define ISCAN_CANCEL    0x0004                  /* cancel current scan */
#define ISCAN_START     0x0008                  /* 1st time through next_scan */
        unsigned long ss_chanmindwell;          /* min dwell on curchan */
        unsigned long ss_scanend;               /* time scan must stop */
        u_int ss_duration;                      /* duration for next scan */
        struct tasklet_struct ss_pwrsav;        /* sta ps ena tasklet */
        struct timer_list ss_scan_timer;        /* scan timer */
};
#define SCAN_PRIVATE(_ss)       ((struct scan_state *)(_ss))

/*
 * Amount of time to go off-channel during a background
 * scan.  This value should be large enough to catch most
 * APs but short enough that we can return on-channel
 * before our listen interval expires.
 *
 * XXX tunable
 * XXX check against configured listen interval
 */
#define IEEE80211_SCAN_OFFCHANNEL       msecs_to_jiffies(150)

/*
 * Roaming-related defaults.  RSSI thresholds are as returned by the
 * driver (dBm).  Transmit rate thresholds are IEEE rate codes (i.e
 * .5M units).
 */
#define SCAN_VALID_DEFAULT              60      /* scan cache valid age (secs) */
#define ROAM_RSSI_11A_DEFAULT           9       /* rssi threshold for 11a bss */
#define ROAM_RSSI_11G_DEFAULT           9       /* rssi threshold for 11g bss */
#define ROAM_RSSI_11BONLY_DEFAULT       9       /* rssi threshold for 11b-only bss */
#define ROAM_RATE_11A_DEFAULT           2 * 24  /* tx rate threshold for 11a bss */
#define ROAM_RATE_11G_DEFAULT           2 * 9   /* tx rate threshold for 11g bss */
#define ROAM_RATE_11BONLY_DEFAULT       2 * 5   /* tx rate threshold for 11b-only bss */

static void scan_restart_pwrsav(unsigned long);
static void scan_next(unsigned long);

void
ieee80211_scan_attach(struct ieee80211com *ic)
{
        struct scan_state *ss;

        ic->ic_roaming = IEEE80211_ROAMING_AUTO;

        MALLOC(ss, struct scan_state *, sizeof(struct scan_state),
                M_80211_SCAN, M_NOWAIT | M_ZERO);
        if (ss != NULL) {
                init_timer(&ss->ss_scan_timer);
                ss->ss_scan_timer.function = scan_next;
                ss->ss_scan_timer.data = (unsigned long) ss;
                tasklet_init(&ss->ss_pwrsav, scan_restart_pwrsav,
                        (unsigned long) ss);
                ic->ic_scan = &ss->base;
        } else
                ic->ic_scan = NULL;
}

void
ieee80211_scan_detach(struct ieee80211com *ic)
{
        struct ieee80211_scan_state *ss = ic->ic_scan;

        if (ss != NULL) {
                del_timer(&SCAN_PRIVATE(ss)->ss_scan_timer);
                tasklet_kill(&SCAN_PRIVATE(ss)->ss_pwrsav);
                if (ss->ss_ops != NULL) {
                        ss->ss_ops->scan_detach(ss);
                        ss->ss_ops = NULL;
                }
                ic->ic_flags &= ~IEEE80211_F_SCAN;
                ic->ic_scan = NULL;
                FREE(SCAN_PRIVATE(ss), M_80211_SCAN);
        }
}

void
ieee80211_scan_vattach(struct ieee80211vap *vap)
{
        vap->iv_bgscanidle = msecs_to_jiffies(IEEE80211_BGSCAN_IDLE_DEFAULT);
        vap->iv_bgscanintvl = IEEE80211_BGSCAN_INTVAL_DEFAULT * HZ;
        vap->iv_scanvalid = SCAN_VALID_DEFAULT * HZ;
        vap->iv_roam.rssi11a = ROAM_RSSI_11A_DEFAULT;
        vap->iv_roam.rssi11g = ROAM_RSSI_11G_DEFAULT;
        vap->iv_roam.rssi11bOnly = ROAM_RSSI_11BONLY_DEFAULT;
        vap->iv_roam.rate11a = ROAM_RATE_11A_DEFAULT;
        vap->iv_roam.rate11g = ROAM_RATE_11G_DEFAULT;
        vap->iv_roam.rate11bOnly = ROAM_RATE_11BONLY_DEFAULT;
}

void
ieee80211_scan_vdetach(struct ieee80211vap *vap)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_scan_state *ss = ic->ic_scan;

        IEEE80211_LOCK_IRQ(ic);
        if (ss->ss_vap == vap) {
                if (ic->ic_flags & IEEE80211_F_SCAN) {
                        del_timer(&SCAN_PRIVATE(ss)->ss_scan_timer);
                        ic->ic_flags &= ~IEEE80211_F_SCAN;
                }
                if (ss->ss_ops != NULL) {
                        ss->ss_ops->scan_detach(ss);
                        ss->ss_ops = NULL;
                }
        }
        IEEE80211_UNLOCK_IRQ(ic);
}

/*
 * Simple-minded scanner module support.
 */
#define IEEE80211_SCANNER_MAX   (IEEE80211_M_MONITOR+1)

static const char *scan_modnames[IEEE80211_SCANNER_MAX] = {
        [IEEE80211_M_IBSS]      = "wlan_scan_sta",
        [IEEE80211_M_STA]       = "wlan_scan_sta",
        [IEEE80211_M_AHDEMO]    = "wlan_scan_sta",
        [IEEE80211_M_HOSTAP]    = "wlan_scan_ap",
};
static const struct ieee80211_scanner *scanners[IEEE80211_SCANNER_MAX];

/* If try load is set, this function will attempt to automatically load the
 * requested module if it is not present. This is on operation that may sleep.
 * Therefore:
 * if !!tryload, then Context: process
 */
const struct ieee80211_scanner *
ieee80211_scanner_get(enum ieee80211_opmode mode, int tryload)
{
        int err;
        if (mode >= IEEE80211_SCANNER_MAX)
                return NULL;
        if (scan_modnames[mode] == NULL)
                return NULL;
        if (scanners[mode] == NULL && tryload) {
                err = ieee80211_load_module(scan_modnames[mode]);
                if (scanners[mode] == NULL || err)
                        printk(KERN_WARNING "unable to load %s\n", scan_modnames[mode]);
        }
        return scanners[mode];
}
EXPORT_SYMBOL(ieee80211_scanner_get);

void
ieee80211_scanner_register(enum ieee80211_opmode mode,
        const struct ieee80211_scanner *scan)
{
        if (mode >= IEEE80211_SCANNER_MAX)
                return;
        scanners[mode] = scan;
}
EXPORT_SYMBOL(ieee80211_scanner_register);

void
ieee80211_scanner_unregister(enum ieee80211_opmode mode,
        const struct ieee80211_scanner *scan)
{
        if (mode >= IEEE80211_SCANNER_MAX)
                return;
        if (scanners[mode] == scan)
                scanners[mode] = NULL;
}
EXPORT_SYMBOL(ieee80211_scanner_unregister);

void
ieee80211_scanner_unregister_all(const struct ieee80211_scanner *scan)
{
        int m;

        for (m = 0; m < IEEE80211_SCANNER_MAX; m++)
                if (scanners[m] == scan)
                        scanners[m] = NULL;
}
EXPORT_SYMBOL(ieee80211_scanner_unregister_all);

static void
change_channel(struct ieee80211com *ic,
        struct ieee80211_channel *chan)
{
        ic->ic_curchan = chan;
        ic->ic_set_channel(ic);
}

static char
channel_type(const struct ieee80211_channel *c)
{
        if (IEEE80211_IS_CHAN_ST(c))
                return 'S';
        if (IEEE80211_IS_CHAN_108A(c))
                return 'T';
        if (IEEE80211_IS_CHAN_108G(c))
                return 'G';
        if (IEEE80211_IS_CHAN_A(c))
                return 'a';
        if (IEEE80211_IS_CHAN_ANYG(c))
                return 'g';
        if (IEEE80211_IS_CHAN_B(c))
                return 'b';
        return 'f';
}

void
ieee80211_scan_dump_channels(const struct ieee80211_scan_state *ss)
{
        struct ieee80211com *ic = ss->ss_vap->iv_ic;
        const char *sep;
        int i;

        sep = "";
        for (i = ss->ss_next; i < ss->ss_last; i++) {
                const struct ieee80211_channel *c = ss->ss_chans[i];

                printk("%s%u%c", sep, ieee80211_chan2ieee(ic, c),
                        channel_type(c));
                sep = ", ";
        }
}
EXPORT_SYMBOL(ieee80211_scan_dump_channels);

/*
 * Enable station power save mode and start/restart the scanning thread.
 */
static void
scan_restart_pwrsav(unsigned long arg)
{
        struct scan_state *ss = (struct scan_state *)arg;
        struct ieee80211vap *vap = ss->base.ss_vap;
        struct ieee80211com *ic = vap->iv_ic;
        int delay;

        ieee80211_sta_pwrsave(vap, 1);
        /*
         * Use an initial 1ms delay to ensure the null
         * data frame has a chance to go out.
         * XXX: 1ms is a lot, better to trigger scan
         * on TX complete.
         */
        delay = msecs_to_jiffies(1);
        if (delay < 1)
                delay = 1;
        ic->ic_scan_start(ic);                  /* notify driver */
        ss->ss_scanend = jiffies + delay + ss->ss_duration;
        ss->ss_iflags |= ISCAN_START;
        mod_timer(&ss->ss_scan_timer, jiffies + delay);
}

/*
 * Start/restart scanning.  If we're operating in station mode
 * and associated notify the ap we're going into power save mode
 * and schedule a callback to initiate the work (where there's a
 * better context for doing the work).  Otherwise, start the scan
 * directly.
 */
static int
scan_restart(struct scan_state *ss, u_int duration)
{
        struct ieee80211vap *vap = ss->base.ss_vap;
        struct ieee80211com *ic = vap->iv_ic;

        if (ss->base.ss_next == ss->base.ss_last) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: no channels to scan\n", __func__);
                return 0;
        } else {
                if ((vap->iv_opmode == IEEE80211_M_STA) &&
                        (vap->iv_state == IEEE80211_S_RUN) &&
                        !(IEEE80211_VAP_IS_SLEEPING(vap))) {
                        /*
                         * Initiate power save before going off-channel.
                         * Note that we cannot do this directly because
                         * of locking issues; instead we defer it to a
                         * tasklet.
                         */
                        ss->ss_duration = duration;
                        tasklet_schedule(&ss->ss_pwrsav);
                } else {
                        ic->ic_scan_start(ic);          /* notify driver */
                        ss->ss_scanend = jiffies + duration;
                        ss->ss_iflags |= ISCAN_START;
                        mod_timer(&ss->ss_scan_timer, jiffies);
                }
                return 1;
        }
}

static void
copy_ssid(struct ieee80211vap *vap, struct ieee80211_scan_state *ss,
        int nssid, const struct ieee80211_scan_ssid ssids[])
{
        if (nssid > IEEE80211_SCAN_MAX_SSID) {
                /* XXX printk */
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: too many ssid %d, ignoring all of them\n",
                        __func__, nssid);
                return;
        }
        memcpy(ss->ss_ssid, ssids, nssid * sizeof(ssids[0]));
        ss->ss_nssid = nssid;
}

/*
 * Start a scan unless one is already going.
 */
int
ieee80211_start_scan(struct ieee80211vap *vap, int flags, u_int duration,
        u_int nssid, const struct ieee80211_scan_ssid ssids[])
{
        struct ieee80211com *ic = vap->iv_ic;
        const struct ieee80211_scanner *scan;
        struct ieee80211_scan_state *ss = ic->ic_scan;
        int scanning;

        scan = ieee80211_scanner_get(vap->iv_opmode, 0);
        if (scan == NULL) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: no scanner support for mode %u\n",
                        __func__, vap->iv_opmode);
                /* XXX stat */
                return 0;
        }

        IEEE80211_LOCK_IRQ(ic);
        if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: %s scan, duration %lu, desired mode %s, %s%s%s%s\n",
                        __func__,
                        flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
                        duration,
                        ieee80211_phymode_name[vap->iv_des_mode],
                        flags & IEEE80211_SCAN_FLUSH ? "flush" : "append",
                        flags & IEEE80211_SCAN_NOPICK ? ", nopick" : "",
                        flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : "",
                        flags & IEEE80211_SCAN_ONCE ? ", once" : "");

                ss->ss_vap = vap;
                if (ss->ss_ops != scan) {
                        /* switch scanners; detach old, attach new */
                        if (ss->ss_ops != NULL)
                                ss->ss_ops->scan_detach(ss);
                        if (!scan->scan_attach(ss)) {
                                /* XXX attach failure */
                                /* XXX stat+msg */
                                ss->ss_ops = NULL;
                        } else
                                ss->ss_ops = scan;
                }
                if (ss->ss_ops != NULL) {
                        if ((flags & IEEE80211_SCAN_NOSSID) == 0)
                                copy_ssid(vap, ss, nssid, ssids);

                        /* NB: top 4 bits for internal use */
                        ss->ss_flags = flags & 0xfff;
                        if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
                                vap->iv_stats.is_scan_active++;
                        else
                                vap->iv_stats.is_scan_passive++;
                        if (flags & IEEE80211_SCAN_FLUSH)
                                ss->ss_ops->scan_flush(ss);

                        /* NB: flush frames rx'd before 1st channel change */
                        SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
                        ss->ss_ops->scan_start(ss, vap);
                        if (scan_restart(SCAN_PRIVATE(ss), duration))
                                ic->ic_flags |= IEEE80211_F_SCAN;
                }
        } else {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: %s scan already in progress\n", __func__,
                        ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");

                /* If the running scanning has the flag SCAN_NOPICK set, but
                 * the requested scan has not, then we update the running scan
                 * flag. This is needed when wpa_supplicant is used with
                 * ap_scan=1. Without it, the driver will never associate. */
                if (((flags & IEEE80211_SCAN_NOPICK) == 0) &&
                    (ss->ss_flags & IEEE80211_SCAN_NOPICK)) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                                          "%s: clearing SCAN_NOPICK flag\n",
                                          __func__);
                        ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
                }
        }
        
        scanning = (ic->ic_flags & IEEE80211_F_SCAN);
        IEEE80211_UNLOCK_IRQ(ic);

        return scanning;
}
EXPORT_SYMBOL(ieee80211_start_scan);

/*
 * Check the scan cache for an ap/channel to use; if that
 * fails then kick off a new scan.
 */
int
ieee80211_check_scan(struct ieee80211vap *vap, int flags, u_int duration,
        u_int nssid, const struct ieee80211_scan_ssid ssids[],
        int (*action)(struct ieee80211vap *, const struct ieee80211_scan_entry *))
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_scan_state *ss = ic->ic_scan;
        int checkscanlist = 0;

        /*
         * Check if there's a list of scan candidates already.
         * XXX want more than the ap we're currently associated with
         */
        IEEE80211_LOCK_IRQ(ic);
        IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                "%s: %s scan, duration %lu, desired mode %s, %s%s%s%s\n",
                __func__,
                flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
                duration,
                ieee80211_phymode_name[vap->iv_des_mode],
                flags & IEEE80211_SCAN_FLUSH ? "flush" : "append",
                flags & IEEE80211_SCAN_NOPICK ? ", nopick" : "",
                flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : "",
                flags & IEEE80211_SCAN_ONCE ? ", once" : "",
                flags & IEEE80211_SCAN_USECACHE ? ", usecache" : "");

        if (ss->ss_ops != NULL) {
                /* XXX verify ss_ops matches vap->iv_opmode */
                if ((flags & IEEE80211_SCAN_NOSSID) == 0) {
                        /*
                         * Update the ssid list and mark flags so if
                         * we call start_scan it doesn't duplicate work.
                         */
                        copy_ssid(vap, ss, nssid, ssids);
                        flags |= IEEE80211_SCAN_NOSSID;
                }
                if ((ic->ic_flags & IEEE80211_F_SCAN) == 0 &&
                     time_before(jiffies, ic->ic_lastscan + vap->iv_scanvalid)) {
                        /*
                         * We're not currently scanning and the cache is
                         * deemed hot enough to consult.  Lock out others
                         * by marking IEEE80211_F_SCAN while we decide if
                         * something is already in the scan cache we can
                         * use.  Also discard any frames that might come
                         * in while temporarily marked as scanning.
                         */
                        SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
                        ic->ic_flags |= IEEE80211_F_SCAN;
                        checkscanlist = 1;
                }
        }
        IEEE80211_UNLOCK_IRQ(ic);
        if (checkscanlist) {
                /*
                 * ss must be filled out so scan may be restarted "outside"
                 * of the current callstack.
                 */
                ss->ss_flags = flags;
                ss->ss_duration = duration;
                if (ss->ss_ops->scan_end(ss, ss->ss_vap, action, flags & IEEE80211_SCAN_KEEPMODE)) {
                        /* found an ap, just clear the flag */
                        ic->ic_flags &= ~IEEE80211_F_SCAN;
                        return 1;
                }
                /* no ap, clear the flag before starting a scan */
                ic->ic_flags &= ~IEEE80211_F_SCAN;
        }
        if ((flags & IEEE80211_SCAN_USECACHE) == 0)
                return ieee80211_start_scan(vap, flags, duration, nssid, ssids);
        else {
                /* If we *must* use the cache and no ap was found, return failure */
                return 0;
        }
}

/*
 * Restart a previous scan.  If the previous scan completed
 * then we start again using the existing channel list.
 */
int
ieee80211_bg_scan(struct ieee80211vap *vap)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_scan_state *ss = ic->ic_scan;
        int scanning;

        IEEE80211_LOCK_IRQ(ic);
        if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
                u_int duration;
                /*
                 * Go off-channel for a fixed interval that is large
                 * enough to catch most APs but short enough that
                 * we can return on-channel before our listen interval
                 * expires.
                 */
                duration = IEEE80211_SCAN_OFFCHANNEL;

                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: %s scan, jiffies %lu duration %lu\n", __func__,
                        ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
                        jiffies, duration);

                if (ss->ss_ops != NULL) {
                        ss->ss_vap = vap;
                        /*
                         * A background scan does not select a new STA; it
                         * just refreshes the scan cache.  Also, indicate
                         * the scan logic should follow the beacon schedule:
                         * we go off-channel and scan for a while, then
                         * return to the bss channel to receive a beacon,
                         * then go off-channel again.  All during this time
                         * we notify the ap we're in power save mode.  When
                         * the scan is complete, we leave power save mode.
                         * If any beacon indicates there are frames pending
                         * for us then we drop out of power save mode
                         * (and background scan) automatically by way of the
                         * usual STA power save logic.
                         */
                        ss->ss_flags |= IEEE80211_SCAN_NOPICK |
                                IEEE80211_SCAN_BGSCAN;

                        /* If previous scan completed, restart */
                        if (ss->ss_next >= ss->ss_last) {
                                ss->ss_next = 0;
                                if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
                                        vap->iv_stats.is_scan_active++;
                                else
                                        vap->iv_stats.is_scan_passive++;
                                ss->ss_ops->scan_restart(ss, vap);
                        }

                        /* NB: Flush frames RX'd before 1st channel change */
                        SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
                        ss->ss_mindwell = duration;
                        if (scan_restart(SCAN_PRIVATE(ss), duration)) {
                                ic->ic_flags |= IEEE80211_F_SCAN;
                                ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
                        }
                } else {
                        /* XXX msg+stat */
                }
        } else {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: %s scan already in progress\n", __func__,
                        ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
        }
        
        scanning = (ic->ic_flags & IEEE80211_F_SCAN);
        IEEE80211_UNLOCK_IRQ(ic);

        return scanning;
}
EXPORT_SYMBOL(ieee80211_bg_scan);
EXPORT_SYMBOL(ieee80211_cancel_scan);

/*
 * Cancel any scan currently going on.
 */
void
ieee80211_cancel_scan(struct ieee80211vap *vap)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_scan_state *ss = ic->ic_scan;

        IEEE80211_LOCK_IRQ(ic);
        if (ic->ic_flags & IEEE80211_F_SCAN) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: cancel %s scan\n", __func__,
                        ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");

                /* clear bg scan NOPICK and mark cancel request */
                ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
                SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_CANCEL;
                ss->ss_ops->scan_cancel(ss, vap);
                /* force it to fire asap */
                mod_timer(&SCAN_PRIVATE(ss)->ss_scan_timer, jiffies);
        }
        IEEE80211_UNLOCK_IRQ(ic);
}

/*
 * Switch to the next channel marked for scanning.
 */
static void
scan_next(unsigned long arg)
{
#define ISCAN_REP       (ISCAN_MINDWELL | ISCAN_START | ISCAN_DISCARD)
        struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *)arg;
        struct ieee80211vap *vap = ss->ss_vap;
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_channel *chan;
        unsigned long maxdwell, scanend;
        int scanning, scandone, i;

        IEEE80211_LOCK_IRQ(ic);
        scanning = (ic->ic_flags & IEEE80211_F_SCAN) != 0;
        IEEE80211_UNLOCK_IRQ(ic);
        if (!scanning)                  /* canceled */
                return;

again:
        scandone = (ss->ss_next >= ss->ss_last) ||
                ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0);
        scanend = SCAN_PRIVATE(ss)->ss_scanend;
        if (!scandone &&
            (ss->ss_flags & IEEE80211_SCAN_GOTPICK) == 0 &&
            ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_START) ||
             time_before(jiffies + ss->ss_mindwell, scanend))) {
                chan = ss->ss_chans[ss->ss_next++];

                /*
                 * Watch for truncation due to the scan end time.
                 */
                if (time_after(jiffies + ss->ss_maxdwell, scanend))
                        maxdwell = scanend - jiffies;
                else
                        maxdwell = ss->ss_maxdwell;

                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                        "%s: chan %3d%c -> %3d%c [%s, dwell min %lu max %lu]\n",
                        __func__,
                        ieee80211_chan2ieee(ic, ic->ic_curchan),
                                channel_type(ic->ic_curchan),
                        ieee80211_chan2ieee(ic, chan), channel_type(chan),
                        (ss->ss_flags & IEEE80211_SCAN_ACTIVE) &&
                                (chan->ic_flags & IEEE80211_CHAN_PASSIVE) == 0 ?
                                "active" : "passive",
                        ss->ss_mindwell, maxdwell);

                /*
                 * Potentially change channel and phy mode.
                 */
                change_channel(ic, chan);

                /*
                 * If doing an active scan and the channel is not
                 * marked passive-only then send a probe request.
                 * Otherwise just listen for traffic on the channel.
                 */
                if ((ss->ss_flags & IEEE80211_SCAN_ACTIVE) &&
                    (chan->ic_flags & IEEE80211_CHAN_PASSIVE) == 0) {
                        struct net_device *dev = vap->iv_dev;
                        /*
                         * Send a broadcast probe request followed by
                         * any specified directed probe requests.
                         * XXX suppress broadcast probe req?
                         * XXX remove dependence on vap/vap->iv_bss
                         * XXX move to policy code?
                         */
                        ieee80211_send_probereq(vap->iv_bss,
                                vap->iv_myaddr, dev->broadcast,
                                dev->broadcast,
                                "", 0,
                                vap->iv_opt_ie, vap->iv_opt_ie_len);
                        for (i = 0; i < ss->ss_nssid; i++)
                                ieee80211_send_probereq(vap->iv_bss,
                                        vap->iv_myaddr, dev->broadcast,
                                        dev->broadcast,
                                        ss->ss_ssid[i].ssid,
                                        ss->ss_ssid[i].len,
                                        vap->iv_opt_ie, vap->iv_opt_ie_len);
                }
                SCAN_PRIVATE(ss)->ss_chanmindwell = jiffies + ss->ss_mindwell;
                mod_timer(&SCAN_PRIVATE(ss)->ss_scan_timer, jiffies + maxdwell);
                /* clear mindwell lock and initial channel change flush */
                SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
        } else {
                ic->ic_scan_end(ic);            /* notify driver */
                /*
                 * Record scan complete time.  Note that we also do
                 * this when canceled so any background scan will
                 * not be restarted for a while.
                 */
                if (scandone)
                        ic->ic_lastscan = jiffies;
                /* return to the bss channel */
                if ((ic->ic_bsschan != IEEE80211_CHAN_ANYC) &&
                    (ic->ic_curchan != ic->ic_bsschan))
                        change_channel(ic, ic->ic_bsschan);
                /* clear internal flags and any indication of a pick */
                SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
                ss->ss_flags &= ~IEEE80211_SCAN_GOTPICK;

                /*
                 * If not canceled and scan completed, do post-processing.
                 * If the callback function returns 0, then it wants to
                 * continue/restart scanning.  Unfortunately we needed to
                 * notify the driver to end the scan above to avoid having
                 * rx frames alter the scan candidate list.
                 */
                if (((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) &&
                    !ss->ss_ops->scan_end(ss, vap, NULL, 0) &&
                    ((ss->ss_flags & IEEE80211_SCAN_ONCE) == 0) &&
                    time_before(jiffies + ss->ss_mindwell, scanend)) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                                "%s: done, restart "
                                "[jiffies %lu, dwell min %lu scanend %lu]\n",
                                __func__,
                                jiffies, ss->ss_mindwell, scanend);
                        ss->ss_next = 0;        /* reset to beginning */
                        if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
                                vap->iv_stats.is_scan_active++;
                        else
                                vap->iv_stats.is_scan_passive++;

                        ic->ic_scan_start(ic);  /* notify driver */
                        goto again;
                } else {
                        if ((ss->ss_flags & IEEE80211_SCAN_BGSCAN) == 0)
                                scandone = 1;

                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                                "%s: %s, "
                                "[jiffies %lu, dwell min %lu scanend %lu]\n",
                                __func__, scandone ? "done" : "stopped",
                                jiffies, ss->ss_mindwell, scanend);

                        /*
                         * Clear the SCAN bit first in case frames are
                         * pending on the station power save queue.  If
                         * we defer this then the dispatch of the frames
                         * may generate a request to cancel scanning.
                         */
                        ic->ic_flags &= ~IEEE80211_F_SCAN;

                        /*
                         * Drop out of power save mode when a scan has
                         * completed.  If this scan was prematurely terminated
                         * because it is a background scan then don't notify
                         * the ap; we'll either return to scanning after we
                         * receive the beacon frame or we'll drop out of power
                         * save mode because the beacon indicates we have frames
                         * waiting for us.
                         */
                        if (scandone) {
                                ieee80211_sta_pwrsave(vap, 0);
                                if (ss->ss_next >= ss->ss_last) {
                                        ieee80211_notify_scan_done(vap);
                                        ic->ic_flags_ext &= ~IEEE80211_FEXT_BGSCAN;
                                }
                        }
                        SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_CANCEL;
                        ss->ss_flags &=
                            ~(IEEE80211_SCAN_ONCE | IEEE80211_SCAN_PICK1ST);
                }
        }
#undef ISCAN_REP
}

#ifdef IEEE80211_DEBUG
static void
dump_probe_beacon(u_int8_t subtype, int isnew,
        const u_int8_t mac[IEEE80211_ADDR_LEN],
        const struct ieee80211_scanparams *sp)
{

        printk("[" MAC_FMT "] %s%s on chan %u (bss chan %u) ",
                MAC_ADDR(mac), isnew ? "new " : "",
                ieee80211_mgt_subtype_name[subtype >> IEEE80211_FC0_SUBTYPE_SHIFT],
                sp->chan, sp->bchan);
        ieee80211_print_essid(sp->ssid + 2, sp->ssid[1]);
        printk("\n");

        if (isnew) {
                printk("[" MAC_FMT "] caps 0x%x bintval %u erp 0x%x",
                        MAC_ADDR(mac), sp->capinfo, sp->bintval, sp->erp);
                if (sp->country != NULL) {
#ifdef __FreeBSD__
                        printk(" country info %*D",
                                sp->country[1], sp->country + 2, " ");
#else
                        int i;
                        printk(" country info");
                        for (i = 0; i < sp->country[1]; i++)
                                printk(" %02x", sp->country[i + 2]);
#endif
                }
                printk("\n");
        }
}
#endif /* IEEE80211_DEBUG */

/*
 * Process a beacon or probe response frame.
 */
void
ieee80211_add_scan(struct ieee80211vap *vap,
        const struct ieee80211_scanparams *sp,
        const struct ieee80211_frame *wh,
        int subtype, int rssi, u_int64_t rtsf)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_scan_state *ss = ic->ic_scan;

        /*
         * Frames received during startup are discarded to avoid
         * using scan state setup on the initial entry to the timer
         * callback.  This can occur because the device may enable
         * rx prior to our doing the initial channel change in the
         * timer routine (we defer the channel change to the timer
         * code to simplify locking on linux).
         */
        if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_DISCARD)
                return;
#ifdef IEEE80211_DEBUG
        if (ieee80211_msg_scan(vap) && (ic->ic_flags & IEEE80211_F_SCAN))
                dump_probe_beacon(subtype, 1, wh->i_addr2, sp);
#endif
        if (ss->ss_ops != NULL &&
            ss->ss_ops->scan_add(ss, sp, wh, subtype, rssi, rtsf)) {
                /*
                 * If we've reached the min dwell time terminate
                 * the timer so we'll switch to the next channel.
                 */
                if ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_MINDWELL) == 0 &&
                    time_after_eq(jiffies, SCAN_PRIVATE(ss)->ss_chanmindwell)) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
                                "%s: chan %3d%c min dwell met (%lu > %lu)\n",
                                __func__,
                                ieee80211_chan2ieee(ic, ic->ic_curchan),
                                        channel_type(ic->ic_curchan),
                                jiffies, SCAN_PRIVATE(ss)->ss_chanmindwell);
                        /*
                         * XXX
                         * We want to just kick the timer and still
                         * process frames until it fires but linux
                         * will livelock unless we discard frames.
                         */
#if 0
                        SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_MINDWELL;
#else
                        SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
#endif
                        /* NB: trigger at next clock tick */
                        mod_timer(&SCAN_PRIVATE(ss)->ss_scan_timer, jiffies);
                }
        }
}

/*
 * Timeout/age scan cache entries; called from sta timeout
 * timer (XXX should be self-contained).
 */
void
ieee80211_scan_timeout(struct ieee80211com *ic)
{
        struct ieee80211_scan_state *ss = ic->ic_scan;

        if (ss->ss_ops != NULL)
                ss->ss_ops->scan_age(ss);
}

/*
 * Mark a scan cache entry after a successful associate.
 */
void
ieee80211_scan_assoc_success(struct ieee80211com *ic, const u_int8_t mac[])
{
        struct ieee80211_scan_state *ss = ic->ic_scan;

        if (ss->ss_ops != NULL) {
                IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
                        mac, "%s",  __func__);
                ss->ss_ops->scan_assoc_success(ss, mac);
        }
}

/*
 * Demerit a scan cache entry after failing to associate.
 */
void
ieee80211_scan_assoc_fail(struct ieee80211com *ic,
        const u_int8_t mac[], int reason)
{
        struct ieee80211_scan_state *ss = ic->ic_scan;

        if (ss->ss_ops != NULL) {
                IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN, mac,
                        "%s: reason %u", __func__, reason);
                ss->ss_ops->scan_assoc_fail(ss, mac, reason);
        }
}

/*
 * Iterate over the contents of the scan cache.
 */
int
ieee80211_scan_iterate(struct ieee80211com *ic,
        ieee80211_scan_iter_func *f, void *arg)
{
  int res = 0;
  struct ieee80211_scan_state *ss = ic->ic_scan;

  if (ss->ss_ops != NULL) {
        res = ss->ss_ops->scan_iterate(ss, f, arg);
  }
  return res;
}

/*
 * Flush the contents of the scan cache.
 */
void
ieee80211_scan_flush(struct ieee80211com *ic)
{
        struct ieee80211_scan_state *ss = ic->ic_scan;

        if (ss->ss_ops != NULL) {
                IEEE80211_DPRINTF(ss->ss_vap, IEEE80211_MSG_SCAN,
                        "%s\n",  __func__);
                ss->ss_ops->scan_flush(ss);
        }
}

/*
 * Execute radar channel change. This is called when a radar/dfs
 * signal is detected.  AP mode only.  Return 1 on success, 0 on
 * failure
 */
int
ieee80211_scan_dfs_action(struct ieee80211vap *vap,
                          const struct ieee80211_scan_entry *se)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_channel *new_channel = NULL;

        if (!IEEE80211_IS_MODE_DFS_MASTER(vap->iv_opmode))
                return 0;
        if (se != NULL) {
                new_channel = se->se_chan;
                if (new_channel != NULL) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                          "%s: new channel found in scan cache\n",
                                          __func__);
                }
        } else {
                /* No channel was found via scan module, means no good scanlist
                 * was found */
                int chanStart, i, count;
                u_int32_t curChanFlags;

                if ((ic->ic_curchan != NULL) &&
                    (ic->ic_curchan != IEEE80211_CHAN_ANYC)) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                          "%s: ic_curchan is %3d (%4d MHz)\n",
                                          __func__, ic->ic_curchan->ic_ieee,
                                          ic->ic_curchan->ic_freq);
                }

                if ((ic->ic_bsschan != NULL) &&
                    (ic->ic_bsschan != IEEE80211_CHAN_ANYC)) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                          "%s: ic_bsschan is %3d (%4d MHz)\n",
                                          __func__, ic->ic_bsschan->ic_ieee,
                                          ic->ic_bsschan->ic_freq);
                }

                /* According to FCC/ETSI rules on uniform spreading, we shall
                 * select a channel out of the list of usable channels so that
                 * the probability of selecting a given channel shall be the
                 * same for all channels (reference: ETSI 301 893 v1.3.1
                 * $4.6.2.5.1 */
                /* First, we count the usable channels */
                count = 0;
                curChanFlags = (ic->ic_bsschan->ic_flags) &
                        ~(IEEE80211_CHAN_RADAR);
                for (i = 0; i < ic->ic_nchans; i++) {
                        if ((ic->ic_channels[i].ic_ieee !=
                                                ic->ic_bsschan->ic_ieee) &&
                            (ic->ic_channels[i].ic_flags == curChanFlags)) {
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                                "%s: usable channel %3d "
                                                "(%4d MHz)\n",
                                                __func__,
                                                ic->ic_channels[i].ic_ieee,
                                                ic->ic_channels[i].ic_freq);
                                count ++;
                        }
                }

                if (count != 0) {
                        /* Next, we pickup a random usable channel */
                        chanStart = jiffies % count;

                        count = 0;
                        for (i = 0; i < ic->ic_nchans; i++) {
                                if ((ic->ic_channels[i].ic_ieee !=
                                     ic->ic_bsschan->ic_ieee) &&
                                    (ic->ic_channels[i].ic_flags ==
                                     curChanFlags)) {
                                        if (count++ == chanStart) {
                                                new_channel =
                                                        &ic->ic_channels[i];
                                                break;
                                        }
                                }
                        }
                }

                if (new_channel != NULL)
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                        "%s: new random channel found %3d "
                                        "(%4d MHz)\n", __func__,
                                        new_channel->ic_ieee,
                                        new_channel->ic_freq);
        }

        if (!new_channel) {
                /* Search for the first channel with no radar detected */
                int n = 0;
                for (n = 0; n < ic->ic_nchans; n++) {
                        if (0 == (ic->ic_channels[n].ic_flags &
                                                IEEE80211_CHAN_RADAR)) {
                                new_channel = &ic->ic_channels[n];
                                break;
                        }
                }
                if (new_channel != NULL)
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                        "%s: new non-radar channel found\n",
                                        __func__);
        }
        if (new_channel != NULL) {
                /* A suitable scan entry was found, so change channels */
                if (vap->iv_state == IEEE80211_S_RUN) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                          "%s: CSA switching to channel %3d (%4d MHz)\n",
                                          __func__,
                                          new_channel->ic_ieee,
                                          new_channel->ic_freq);

                        ic->ic_chanchange_chan = new_channel->ic_ieee;
                        ic->ic_chanchange_tbtt =
                                IEEE80211_RADAR_CHANCHANGE_TBTT_COUNT;
                        ic->ic_flags |= IEEE80211_F_CHANSWITCH;
                } else {

                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                        "%s: directly switching to channel "
                                        "%3d (%4d MHz)\n", __func__,
                                        new_channel->ic_ieee,
                                        new_channel->ic_freq);

                        /* VAP is not in run state yet. so
                         * change the channel here. */
                        change_channel(ic, new_channel);
                        ic->ic_bsschan = new_channel;
                        if (vap->iv_bss)
                                vap->iv_bss->ni_chan = new_channel;
                }
        } else {
                /* A suitable scan entry was not found */
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_DOTH,
                                  "%s: new channel not found\n", __func__);
                return 0;
        }

        return 1;
}
EXPORT_SYMBOL(ieee80211_scan_dfs_action);