/*
 * Off-channel operation helpers
 *
 * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 * Copyright 2009       Johannes Berg <johannes@sipsolutions.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/export.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.h"

/*
 * Tell our hardware to disable PS.
 * Optionally inform AP that we will go to sleep so that it will buffer
 * the frames while we are doing off-channel work.  This is optional
 * because we *may* be doing work on-operating channel, and want our
 * hardware unconditionally awake, but still let the AP send us normal frames.
 */
static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;

        local->offchannel_ps_enabled = false;

        /* FIXME: what to do when local->pspolling is true? */

        del_timer_sync(&local->dynamic_ps_timer);
        del_timer_sync(&ifmgd->bcn_mon_timer);
        del_timer_sync(&ifmgd->conn_mon_timer);

        cancel_work_sync(&local->dynamic_ps_enable_work);

        if (local->hw.conf.flags & IEEE80211_CONF_PS) {
                local->offchannel_ps_enabled = true;
                local->hw.conf.flags &= ~IEEE80211_CONF_PS;
                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
        }

        if (!local->offchannel_ps_enabled ||
            !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
                /*
                 * If power save was enabled, no need to send a nullfunc
                 * frame because AP knows that we are sleeping. But if the
                 * hardware is creating the nullfunc frame for power save
                 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
                 * enabled) and power save was enabled, the firmware just
                 * sent a null frame with power save disabled. So we need
                 * to send a new nullfunc frame to inform the AP that we
                 * are again sleeping.
                 */
                ieee80211_send_nullfunc(local, sdata, 1);
}

/* inform AP that we are awake again, unless power save is enabled */
static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;

        if (!local->ps_sdata)
                ieee80211_send_nullfunc(local, sdata, 0);
        else if (local->offchannel_ps_enabled) {
                /*
                 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
                 * will send a nullfunc frame with the powersave bit set
                 * even though the AP already knows that we are sleeping.
                 * This could be avoided by sending a null frame with power
                 * save bit disabled before enabling the power save, but
                 * this doesn't gain anything.
                 *
                 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
                 * to send a nullfunc frame because AP already knows that
                 * we are sleeping, let's just enable power save mode in
                 * hardware.
                 */
                /* TODO:  Only set hardware if CONF_PS changed?
                 * TODO:  Should we set offchannel_ps_enabled to false?
                 */
                local->hw.conf.flags |= IEEE80211_CONF_PS;
                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
        } else if (local->hw.conf.dynamic_ps_timeout > 0) {
                /*
                 * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
                 * had been running before leaving the operating channel,
                 * restart the timer now and send a nullfunc frame to inform
                 * the AP that we are awake.
                 */
                ieee80211_send_nullfunc(local, sdata, 0);
                mod_timer(&local->dynamic_ps_timer, jiffies +
                          msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
        }

        ieee80211_sta_reset_beacon_monitor(sdata);
        ieee80211_sta_reset_conn_monitor(sdata);
}

void ieee80211_offchannel_stop_vifs(struct ieee80211_local *local)
{
        struct ieee80211_sub_if_data *sdata;

        if (WARN_ON(local->use_chanctx))
                return;

        /*
         * notify the AP about us leaving the channel and stop all
         * STA interfaces.
         */

        /*
         * Stop queues and transmit all frames queued by the driver
         * before sending nullfunc to enable powersave at the AP.
         */
        ieee80211_stop_queues_by_reason(&local->hw, IEEE80211_MAX_QUEUE_MAP,
                                        IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL);
        ieee80211_flush_queues(local, NULL);

        mutex_lock(&local->iflist_mtx);
        list_for_each_entry(sdata, &local->interfaces, list) {
                if (!ieee80211_sdata_running(sdata))
                        continue;

                if (sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE)
                        continue;

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
                        set_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);

                /* Check to see if we should disable beaconing. */
                if (sdata->vif.bss_conf.enable_beacon) {
                        set_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED,
                                &sdata->state);
                        sdata->vif.bss_conf.enable_beacon = false;
                        ieee80211_bss_info_change_notify(
                                sdata, BSS_CHANGED_BEACON_ENABLED);
                }

                if (sdata->vif.type == NL80211_IFTYPE_STATION &&
                    sdata->u.mgd.associated)
                        ieee80211_offchannel_ps_enable(sdata);
        }
        mutex_unlock(&local->iflist_mtx);
}

void ieee80211_offchannel_return(struct ieee80211_local *local)
{
        struct ieee80211_sub_if_data *sdata;

        if (WARN_ON(local->use_chanctx))
                return;

        mutex_lock(&local->iflist_mtx);
        list_for_each_entry(sdata, &local->interfaces, list) {
                if (sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE)
                        continue;

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
                        clear_bit(SDATA_STATE_OFFCHANNEL, &sdata->state);

                if (!ieee80211_sdata_running(sdata))
                        continue;

                /* Tell AP we're back */
                if (sdata->vif.type == NL80211_IFTYPE_STATION &&
                    sdata->u.mgd.associated)
                        ieee80211_offchannel_ps_disable(sdata);

                if (test_and_clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED,
                                       &sdata->state)) {
                        sdata->vif.bss_conf.enable_beacon = true;
                        ieee80211_bss_info_change_notify(
                                sdata, BSS_CHANGED_BEACON_ENABLED);
                }
        }
        mutex_unlock(&local->iflist_mtx);

        ieee80211_wake_queues_by_reason(&local->hw, IEEE80211_MAX_QUEUE_MAP,
                                        IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL);
}

void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc)
{
        if (roc->notified)
                return;

        if (roc->mgmt_tx_cookie) {
                if (!WARN_ON(!roc->frame)) {
                        ieee80211_tx_skb_tid_band(roc->sdata, roc->frame, 7,
                                                  roc->chan->band);
                        roc->frame = NULL;
                }
        } else {
                cfg80211_ready_on_channel(&roc->sdata->wdev, roc->cookie,
                                          roc->chan, roc->req_duration,
                                          GFP_KERNEL);
        }

        roc->notified = true;
}

static void ieee80211_hw_roc_start(struct work_struct *work)
{
        struct ieee80211_local *local =
                container_of(work, struct ieee80211_local, hw_roc_start);
        struct ieee80211_roc_work *roc, *dep, *tmp;

        mutex_lock(&local->mtx);

        if (list_empty(&local->roc_list))
                goto out_unlock;

        roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
                               list);

        if (!roc->started)
                goto out_unlock;

        roc->hw_begun = true;
        roc->hw_start_time = local->hw_roc_start_time;

        ieee80211_handle_roc_started(roc);
        list_for_each_entry_safe(dep, tmp, &roc->dependents, list) {
                ieee80211_handle_roc_started(dep);

                if (dep->duration > roc->duration) {
                        u32 dur = dep->duration;
                        dep->duration = dur - roc->duration;
                        roc->duration = dur;
                        list_move(&dep->list, &roc->list);
                }
        }
 out_unlock:
        mutex_unlock(&local->mtx);
}

void ieee80211_ready_on_channel(struct ieee80211_hw *hw)
{
        struct ieee80211_local *local = hw_to_local(hw);

        local->hw_roc_start_time = jiffies;

        trace_api_ready_on_channel(local);

        ieee80211_queue_work(hw, &local->hw_roc_start);
}
EXPORT_SYMBOL_GPL(ieee80211_ready_on_channel);

void ieee80211_start_next_roc(struct ieee80211_local *local)
{
        struct ieee80211_roc_work *roc;

        lockdep_assert_held(&local->mtx);

        if (list_empty(&local->roc_list)) {
                ieee80211_run_deferred_scan(local);
                return;
        }

        roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
                               list);

        if (WARN_ON_ONCE(roc->started))
                return;

        if (local->ops->remain_on_channel) {
                int ret, duration = roc->duration;

                /* XXX: duplicated, see ieee80211_start_roc_work() */
                if (!duration)
                        duration = 10;

                ret = drv_remain_on_channel(local, roc->sdata, roc->chan,
                                            duration, roc->type);

                roc->started = true;

                if (ret) {
                        wiphy_warn(local->hw.wiphy,
                                   "failed to start next HW ROC (%d)\n", ret);
                        /*
                         * queue the work struct again to avoid recursion
                         * when multiple failures occur
                         */
                        ieee80211_remain_on_channel_expired(&local->hw);
                }
        } else {
                /* delay it a bit */
                ieee80211_queue_delayed_work(&local->hw, &roc->work,
                                             round_jiffies_relative(HZ/2));
        }
}

void ieee80211_roc_notify_destroy(struct ieee80211_roc_work *roc, bool free)
{
        struct ieee80211_roc_work *dep, *tmp;

        if (WARN_ON(roc->to_be_freed))
                return;

        /* was never transmitted */
        if (roc->frame) {
                cfg80211_mgmt_tx_status(&roc->sdata->wdev,
                                        (unsigned long)roc->frame,
                                        roc->frame->data, roc->frame->len,
                                        false, GFP_KERNEL);
                kfree_skb(roc->frame);
        }

        if (!roc->mgmt_tx_cookie)
                cfg80211_remain_on_channel_expired(&roc->sdata->wdev,
                                                   roc->cookie, roc->chan,
                                                   GFP_KERNEL);

        list_for_each_entry_safe(dep, tmp, &roc->dependents, list)
                ieee80211_roc_notify_destroy(dep, true);

        if (free)
                kfree(roc);
        else
                roc->to_be_freed = true;
}

void ieee80211_sw_roc_work(struct work_struct *work)
{
        struct ieee80211_roc_work *roc =
                container_of(work, struct ieee80211_roc_work, work.work);
        struct ieee80211_sub_if_data *sdata = roc->sdata;
        struct ieee80211_local *local = sdata->local;
        bool started;

        mutex_lock(&local->mtx);

        if (roc->to_be_freed)
                goto out_unlock;

        if (roc->abort)
                goto finish;

        if (WARN_ON(list_empty(&local->roc_list)))
                goto out_unlock;

        if (WARN_ON(roc != list_first_entry(&local->roc_list,
                                            struct ieee80211_roc_work,
                                            list)))
                goto out_unlock;

        if (!roc->started) {
                struct ieee80211_roc_work *dep;

                /* start this ROC */

                /* switch channel etc */
                ieee80211_recalc_idle(local);

                local->tmp_channel = roc->chan;
                ieee80211_hw_config(local, 0);

                /* tell userspace or send frame */
                ieee80211_handle_roc_started(roc);
                list_for_each_entry(dep, &roc->dependents, list)
                        ieee80211_handle_roc_started(dep);

                /* if it was pure TX, just finish right away */
                if (!roc->duration)
                        goto finish;

                roc->started = true;
                ieee80211_queue_delayed_work(&local->hw, &roc->work,
                                             msecs_to_jiffies(roc->duration));
        } else {
                /* finish this ROC */
 finish:
                list_del(&roc->list);
                started = roc->started;
                ieee80211_roc_notify_destroy(roc, !roc->abort);

                if (started) {
                        ieee80211_flush_queues(local, NULL);

                        local->tmp_channel = NULL;
                        ieee80211_hw_config(local, 0);

                        ieee80211_offchannel_return(local);
                }

                ieee80211_recalc_idle(local);

                if (started)
                        ieee80211_start_next_roc(local);
                else if (list_empty(&local->roc_list))
                        ieee80211_run_deferred_scan(local);
        }

 out_unlock:
        mutex_unlock(&local->mtx);
}

static void ieee80211_hw_roc_done(struct work_struct *work)
{
        struct ieee80211_local *local =
                container_of(work, struct ieee80211_local, hw_roc_done);
        struct ieee80211_roc_work *roc;

        mutex_lock(&local->mtx);

        if (list_empty(&local->roc_list))
                goto out_unlock;

        roc = list_first_entry(&local->roc_list, struct ieee80211_roc_work,
                               list);

        if (!roc->started)
                goto out_unlock;

        list_del(&roc->list);

        ieee80211_roc_notify_destroy(roc, true);

        /* if there's another roc, start it now */
        ieee80211_start_next_roc(local);

 out_unlock:
        mutex_unlock(&local->mtx);
}

void ieee80211_remain_on_channel_expired(struct ieee80211_hw *hw)
{
        struct ieee80211_local *local = hw_to_local(hw);

        trace_api_remain_on_channel_expired(local);

        ieee80211_queue_work(hw, &local->hw_roc_done);
}
EXPORT_SYMBOL_GPL(ieee80211_remain_on_channel_expired);

void ieee80211_roc_setup(struct ieee80211_local *local)
{
        INIT_WORK(&local->hw_roc_start, ieee80211_hw_roc_start);
        INIT_WORK(&local->hw_roc_done, ieee80211_hw_roc_done);
        INIT_LIST_HEAD(&local->roc_list);
}

void ieee80211_roc_purge(struct ieee80211_local *local,
                         struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_roc_work *roc, *tmp;
        LIST_HEAD(tmp_list);

        mutex_lock(&local->mtx);
        list_for_each_entry_safe(roc, tmp, &local->roc_list, list) {
                if (sdata && roc->sdata != sdata)
                        continue;

                if (roc->started && local->ops->remain_on_channel) {
                        /* can race, so ignore return value */
                        drv_cancel_remain_on_channel(local);
                }

                list_move_tail(&roc->list, &tmp_list);
                roc->abort = true;
        }
        mutex_unlock(&local->mtx);

        list_for_each_entry_safe(roc, tmp, &tmp_list, list) {
                if (local->ops->remain_on_channel) {
                        list_del(&roc->list);
                        ieee80211_roc_notify_destroy(roc, true);
                } else {
                        ieee80211_queue_delayed_work(&local->hw, &roc->work, 0);

                        /* work will clean up etc */
                        flush_delayed_work(&roc->work);
                        WARN_ON(!roc->to_be_freed);
                        kfree(roc);
                }
        }

        WARN_ON_ONCE(!list_empty(&tmp_list));
}