/*
 * Copyright 2012-2013, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
 * Copyright 2012-2013, cozybit Inc.
 *
 * 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 "mesh.h"
#include "wme.h"


/* mesh PS management */

/**
 * mps_qos_null_get - create pre-addressed QoS Null frame for mesh powersave
 */
static struct sk_buff *mps_qos_null_get(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_hdr *nullfunc; /* use 4addr header */
        struct sk_buff *skb;
        int size = sizeof(*nullfunc);
        __le16 fc;

        skb = dev_alloc_skb(local->hw.extra_tx_headroom + size + 2);
        if (!skb)
                return NULL;
        skb_reserve(skb, local->hw.extra_tx_headroom);

        nullfunc = skb_put(skb, size);
        fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_QOS_NULLFUNC);
        ieee80211_fill_mesh_addresses(nullfunc, &fc, sta->sta.addr,
                                      sdata->vif.addr);
        nullfunc->frame_control = fc;
        nullfunc->duration_id = 0;
        nullfunc->seq_ctrl = 0;
        /* no address resolution for this frame -> set addr 1 immediately */
        memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
        skb_put_zero(skb, 2); /* append QoS control field */
        ieee80211_mps_set_frame_flags(sdata, sta, nullfunc);

        return skb;
}

/**
 * mps_qos_null_tx - send a QoS Null to indicate link-specific power mode
 */
static void mps_qos_null_tx(struct sta_info *sta)
{
        struct sk_buff *skb;

        skb = mps_qos_null_get(sta);
        if (!skb)
                return;

        mps_dbg(sta->sdata, "announcing peer-specific power mode to %pM\n",
                sta->sta.addr);

        /* don't unintentionally start a MPSP */
        if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
                u8 *qc = ieee80211_get_qos_ctl((void *) skb->data);

                qc[0] |= IEEE80211_QOS_CTL_EOSP;
        }

        ieee80211_tx_skb(sta->sdata, skb);
}

/**
 * ieee80211_mps_local_status_update - track status of local link-specific PMs
 *
 * @sdata: local mesh subif
 *
 * sets the non-peer power mode and triggers the driver PS (re-)configuration
 * Return BSS_CHANGED_BEACON if a beacon update is necessary.
 */
u32 ieee80211_mps_local_status_update(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
        struct sta_info *sta;
        bool peering = false;
        int light_sleep_cnt = 0;
        int deep_sleep_cnt = 0;
        u32 changed = 0;
        enum nl80211_mesh_power_mode nonpeer_pm;

        rcu_read_lock();
        list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
                if (sdata != sta->sdata)
                        continue;

                switch (sta->mesh->plink_state) {
                case NL80211_PLINK_OPN_SNT:
                case NL80211_PLINK_OPN_RCVD:
                case NL80211_PLINK_CNF_RCVD:
                        peering = true;
                        break;
                case NL80211_PLINK_ESTAB:
                        if (sta->mesh->local_pm == NL80211_MESH_POWER_LIGHT_SLEEP)
                                light_sleep_cnt++;
                        else if (sta->mesh->local_pm == NL80211_MESH_POWER_DEEP_SLEEP)
                                deep_sleep_cnt++;
                        break;
                default:
                        break;
                }
        }
        rcu_read_unlock();

        /*
         * Set non-peer mode to active during peering/scanning/authentication
         * (see IEEE802.11-2012 13.14.8.3). The non-peer mesh power mode is
         * deep sleep if the local STA is in light or deep sleep towards at
         * least one mesh peer (see 13.14.3.1). Otherwise, set it to the
         * user-configured default value.
         */
        if (peering) {
                mps_dbg(sdata, "setting non-peer PM to active for peering\n");
                nonpeer_pm = NL80211_MESH_POWER_ACTIVE;
        } else if (light_sleep_cnt || deep_sleep_cnt) {
                mps_dbg(sdata, "setting non-peer PM to deep sleep\n");
                nonpeer_pm = NL80211_MESH_POWER_DEEP_SLEEP;
        } else {
                mps_dbg(sdata, "setting non-peer PM to user value\n");
                nonpeer_pm = ifmsh->mshcfg.power_mode;
        }

        /* need update if sleep counts move between 0 and non-zero */
        if (ifmsh->nonpeer_pm != nonpeer_pm ||
            !ifmsh->ps_peers_light_sleep != !light_sleep_cnt ||
            !ifmsh->ps_peers_deep_sleep != !deep_sleep_cnt)
                changed = BSS_CHANGED_BEACON;

        ifmsh->nonpeer_pm = nonpeer_pm;
        ifmsh->ps_peers_light_sleep = light_sleep_cnt;
        ifmsh->ps_peers_deep_sleep = deep_sleep_cnt;

        return changed;
}

/**
 * ieee80211_mps_set_sta_local_pm - set local PM towards a mesh STA
 *
 * @sta: mesh STA
 * @pm: the power mode to set
 * Return BSS_CHANGED_BEACON if a beacon update is in order.
 */
u32 ieee80211_mps_set_sta_local_pm(struct sta_info *sta,
                                   enum nl80211_mesh_power_mode pm)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;

        if (sta->mesh->local_pm == pm)
                return 0;

        mps_dbg(sdata, "local STA operates in mode %d with %pM\n",
                pm, sta->sta.addr);

        sta->mesh->local_pm = pm;

        /*
         * announce peer-specific power mode transition
         * (see IEEE802.11-2012 13.14.3.2 and 13.14.3.3)
         */
        if (sta->mesh->plink_state == NL80211_PLINK_ESTAB)
                mps_qos_null_tx(sta);

        return ieee80211_mps_local_status_update(sdata);
}

/**
 * ieee80211_mps_set_frame_flags - set mesh PS flags in FC (and QoS Control)
 *
 * @sdata: local mesh subif
 * @sta: mesh STA
 * @hdr: 802.11 frame header
 *
 * see IEEE802.11-2012 8.2.4.1.7 and 8.2.4.5.11
 *
 * NOTE: sta must be given when an individually-addressed QoS frame header
 * is handled, for group-addressed and management frames it is not used
 */
void ieee80211_mps_set_frame_flags(struct ieee80211_sub_if_data *sdata,
                                   struct sta_info *sta,
                                   struct ieee80211_hdr *hdr)
{
        enum nl80211_mesh_power_mode pm;
        u8 *qc;

        if (WARN_ON(is_unicast_ether_addr(hdr->addr1) &&
                    ieee80211_is_data_qos(hdr->frame_control) &&
                    !sta))
                return;

        if (is_unicast_ether_addr(hdr->addr1) &&
            ieee80211_is_data_qos(hdr->frame_control) &&
            sta->mesh->plink_state == NL80211_PLINK_ESTAB)
                pm = sta->mesh->local_pm;
        else
                pm = sdata->u.mesh.nonpeer_pm;

        if (pm == NL80211_MESH_POWER_ACTIVE)
                hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_PM);
        else
                hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PM);

        if (!ieee80211_is_data_qos(hdr->frame_control))
                return;

        qc = ieee80211_get_qos_ctl(hdr);

        if ((is_unicast_ether_addr(hdr->addr1) &&
             pm == NL80211_MESH_POWER_DEEP_SLEEP) ||
            (is_multicast_ether_addr(hdr->addr1) &&
             sdata->u.mesh.ps_peers_deep_sleep > 0))
                qc[1] |= (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
        else
                qc[1] &= ~(IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
}

/**
 * ieee80211_mps_sta_status_update - update buffering status of neighbor STA
 *
 * @sta: mesh STA
 *
 * called after change of peering status or non-peer/peer-specific power mode
 */
void ieee80211_mps_sta_status_update(struct sta_info *sta)
{
        enum nl80211_mesh_power_mode pm;
        bool do_buffer;

        /* For non-assoc STA, prevent buffering or frame transmission */
        if (sta->sta_state < IEEE80211_STA_ASSOC)
                return;

        /*
         * use peer-specific power mode if peering is established and the
         * peer's power mode is known
         */
        if (sta->mesh->plink_state == NL80211_PLINK_ESTAB &&
            sta->mesh->peer_pm != NL80211_MESH_POWER_UNKNOWN)
                pm = sta->mesh->peer_pm;
        else
                pm = sta->mesh->nonpeer_pm;

        do_buffer = (pm != NL80211_MESH_POWER_ACTIVE);

        /* clear the MPSP flags for non-peers or active STA */
        if (sta->mesh->plink_state != NL80211_PLINK_ESTAB) {
                clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
                clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
        } else if (!do_buffer) {
                clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
        }

        /* Don't let the same PS state be set twice */
        if (test_sta_flag(sta, WLAN_STA_PS_STA) == do_buffer)
                return;

        if (do_buffer) {
                set_sta_flag(sta, WLAN_STA_PS_STA);
                atomic_inc(&sta->sdata->u.mesh.ps.num_sta_ps);
                mps_dbg(sta->sdata, "start PS buffering frames towards %pM\n",
                        sta->sta.addr);
        } else {
                ieee80211_sta_ps_deliver_wakeup(sta);
        }
}

static void mps_set_sta_peer_pm(struct sta_info *sta,
                                struct ieee80211_hdr *hdr)
{
        enum nl80211_mesh_power_mode pm;
        u8 *qc = ieee80211_get_qos_ctl(hdr);

        /*
         * Test Power Management field of frame control (PW) and
         * mesh power save level subfield of QoS control field (PSL)
         *
         * | PM | PSL| Mesh PM |
         * +----+----+---------+
         * | 0  |Rsrv|  Active |
         * | 1  | 0  |  Light  |
         * | 1  | 1  |  Deep   |
         */
        if (ieee80211_has_pm(hdr->frame_control)) {
                if (qc[1] & (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8))
                        pm = NL80211_MESH_POWER_DEEP_SLEEP;
                else
                        pm = NL80211_MESH_POWER_LIGHT_SLEEP;
        } else {
                pm = NL80211_MESH_POWER_ACTIVE;
        }

        if (sta->mesh->peer_pm == pm)
                return;

        mps_dbg(sta->sdata, "STA %pM enters mode %d\n",
                sta->sta.addr, pm);

        sta->mesh->peer_pm = pm;

        ieee80211_mps_sta_status_update(sta);
}

static void mps_set_sta_nonpeer_pm(struct sta_info *sta,
                                   struct ieee80211_hdr *hdr)
{
        enum nl80211_mesh_power_mode pm;

        if (ieee80211_has_pm(hdr->frame_control))
                pm = NL80211_MESH_POWER_DEEP_SLEEP;
        else
                pm = NL80211_MESH_POWER_ACTIVE;

        if (sta->mesh->nonpeer_pm == pm)
                return;

        mps_dbg(sta->sdata, "STA %pM sets non-peer mode to %d\n",
                sta->sta.addr, pm);

        sta->mesh->nonpeer_pm = pm;

        ieee80211_mps_sta_status_update(sta);
}

/**
 * ieee80211_mps_rx_h_sta_process - frame receive handler for mesh powersave
 *
 * @sta: STA info that transmitted the frame
 * @hdr: IEEE 802.11 (QoS) Header
 */
void ieee80211_mps_rx_h_sta_process(struct sta_info *sta,
                                    struct ieee80211_hdr *hdr)
{
        if (is_unicast_ether_addr(hdr->addr1) &&
            ieee80211_is_data_qos(hdr->frame_control)) {
                /*
                 * individually addressed QoS Data/Null frames contain
                 * peer link-specific PS mode towards the local STA
                 */
                mps_set_sta_peer_pm(sta, hdr);

                /* check for mesh Peer Service Period trigger frames */
                ieee80211_mpsp_trigger_process(ieee80211_get_qos_ctl(hdr),
                                               sta, false, false);
        } else {
                /*
                 * can only determine non-peer PS mode
                 * (see IEEE802.11-2012 8.2.4.1.7)
                 */
                mps_set_sta_nonpeer_pm(sta, hdr);
        }
}


/* mesh PS frame release */

static void mpsp_trigger_send(struct sta_info *sta, bool rspi, bool eosp)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        struct sk_buff *skb;
        struct ieee80211_hdr *nullfunc;
        struct ieee80211_tx_info *info;
        u8 *qc;

        skb = mps_qos_null_get(sta);
        if (!skb)
                return;

        nullfunc = (struct ieee80211_hdr *) skb->data;
        if (!eosp)
                nullfunc->frame_control |=
                                cpu_to_le16(IEEE80211_FCTL_MOREDATA);
        /*
         * | RSPI | EOSP |  MPSP triggering   |
         * +------+------+--------------------+
         * |  0   |  0   | local STA is owner |
         * |  0   |  1   | no MPSP (MPSP end) |
         * |  1   |  0   | both STA are owner |
         * |  1   |  1   | peer STA is owner  | see IEEE802.11-2012 13.14.9.2
         */
        qc = ieee80211_get_qos_ctl(nullfunc);
        if (rspi)
                qc[1] |= (IEEE80211_QOS_CTL_RSPI >> 8);
        if (eosp)
                qc[0] |= IEEE80211_QOS_CTL_EOSP;

        info = IEEE80211_SKB_CB(skb);

        info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER |
                       IEEE80211_TX_CTL_REQ_TX_STATUS;

        mps_dbg(sdata, "sending MPSP trigger%s%s to %pM\n",
                rspi ? " RSPI" : "", eosp ? " EOSP" : "", sta->sta.addr);

        ieee80211_tx_skb(sdata, skb);
}

/**
 * mpsp_qos_null_append - append QoS Null frame to MPSP skb queue if needed
 *
 * To properly end a mesh MPSP the last transmitted frame has to set the EOSP
 * flag in the QoS Control field. In case the current tailing frame is not a
 * QoS Data frame, append a QoS Null to carry the flag.
 */
static void mpsp_qos_null_append(struct sta_info *sta,
                                 struct sk_buff_head *frames)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        struct sk_buff *new_skb, *skb = skb_peek_tail(frames);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct ieee80211_tx_info *info;

        if (ieee80211_is_data_qos(hdr->frame_control))
                return;

        new_skb = mps_qos_null_get(sta);
        if (!new_skb)
                return;

        mps_dbg(sdata, "appending QoS Null in MPSP towards %pM\n",
                sta->sta.addr);
        /*
         * This frame has to be transmitted last. Assign lowest priority to
         * make sure it cannot pass other frames when releasing multiple ACs.
         */
        new_skb->priority = 1;
        skb_set_queue_mapping(new_skb, IEEE80211_AC_BK);
        ieee80211_set_qos_hdr(sdata, new_skb);

        info = IEEE80211_SKB_CB(new_skb);
        info->control.vif = &sdata->vif;
        info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;

        __skb_queue_tail(frames, new_skb);
}

/**
 * mps_frame_deliver - transmit frames during mesh powersave
 *
 * @sta: STA info to transmit to
 * @n_frames: number of frames to transmit. -1 for all
 */
static void mps_frame_deliver(struct sta_info *sta, int n_frames)
{
        struct ieee80211_local *local = sta->sdata->local;
        int ac;
        struct sk_buff_head frames;
        struct sk_buff *skb;
        bool more_data = false;

        skb_queue_head_init(&frames);

        /* collect frame(s) from buffers */
        for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
                while (n_frames != 0) {
                        skb = skb_dequeue(&sta->tx_filtered[ac]);
                        if (!skb) {
                                skb = skb_dequeue(
                                        &sta->ps_tx_buf[ac]);
                                if (skb)
                                        local->total_ps_buffered--;
                        }
                        if (!skb)
                                break;
                        n_frames--;
                        __skb_queue_tail(&frames, skb);
                }

                if (!skb_queue_empty(&sta->tx_filtered[ac]) ||
                    !skb_queue_empty(&sta->ps_tx_buf[ac]))
                        more_data = true;
        }

        /* nothing to send? -> EOSP */
        if (skb_queue_empty(&frames)) {
                mpsp_trigger_send(sta, false, true);
                return;
        }

        /* in a MPSP make sure the last skb is a QoS Data frame */
        if (test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
                mpsp_qos_null_append(sta, &frames);

        mps_dbg(sta->sdata, "sending %d frames to PS STA %pM\n",
                skb_queue_len(&frames), sta->sta.addr);

        /* prepare collected frames for transmission */
        skb_queue_walk(&frames, skb) {
                struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
                struct ieee80211_hdr *hdr = (void *) skb->data;

                /*
                 * Tell TX path to send this frame even though the
                 * STA may still remain is PS mode after this frame
                 * exchange.
                 */
                info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER;

                if (more_data || !skb_queue_is_last(&frames, skb))
                        hdr->frame_control |=
                                cpu_to_le16(IEEE80211_FCTL_MOREDATA);
                else
                        hdr->frame_control &=
                                cpu_to_le16(~IEEE80211_FCTL_MOREDATA);

                if (skb_queue_is_last(&frames, skb) &&
                    ieee80211_is_data_qos(hdr->frame_control)) {
                        u8 *qoshdr = ieee80211_get_qos_ctl(hdr);

                        /* MPSP trigger frame ends service period */
                        *qoshdr |= IEEE80211_QOS_CTL_EOSP;
                        info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
                }
        }

        ieee80211_add_pending_skbs(local, &frames);
        sta_info_recalc_tim(sta);
}

/**
 * ieee80211_mpsp_trigger_process - track status of mesh Peer Service Periods
 *
 * @qc: QoS Control field
 * @sta: peer to start a MPSP with
 * @tx: frame was transmitted by the local STA
 * @acked: frame has been transmitted successfully
 *
 * NOTE: active mode STA may only serve as MPSP owner
 */
void ieee80211_mpsp_trigger_process(u8 *qc, struct sta_info *sta,
                                    bool tx, bool acked)
{
        u8 rspi = qc[1] & (IEEE80211_QOS_CTL_RSPI >> 8);
        u8 eosp = qc[0] & IEEE80211_QOS_CTL_EOSP;

        if (tx) {
                if (rspi && acked)
                        set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);

                if (eosp)
                        clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
                else if (acked &&
                         test_sta_flag(sta, WLAN_STA_PS_STA) &&
                         !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
                        mps_frame_deliver(sta, -1);
        } else {
                if (eosp)
                        clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
                else if (sta->mesh->local_pm != NL80211_MESH_POWER_ACTIVE)
                        set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);

                if (rspi && !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
                        mps_frame_deliver(sta, -1);
        }
}

/**
 * ieee80211_mps_frame_release - release frames buffered due to mesh power save
 *
 * @sta: mesh STA
 * @elems: IEs of beacon or probe response
 *
 * For peers if we have individually-addressed frames buffered or the peer
 * indicates buffered frames, send a corresponding MPSP trigger frame. Since
 * we do not evaluate the awake window duration, QoS Nulls are used as MPSP
 * trigger frames. If the neighbour STA is not a peer, only send single frames.
 */
void ieee80211_mps_frame_release(struct sta_info *sta,
                                 struct ieee802_11_elems *elems)
{
        int ac, buffer_local = 0;
        bool has_buffered = false;

        if (sta->mesh->plink_state == NL80211_PLINK_ESTAB)
                has_buffered = ieee80211_check_tim(elems->tim, elems->tim_len,
                                                   sta->mesh->aid);

        if (has_buffered)
                mps_dbg(sta->sdata, "%pM indicates buffered frames\n",
                        sta->sta.addr);

        /* only transmit to PS STA with announced, non-zero awake window */
        if (test_sta_flag(sta, WLAN_STA_PS_STA) &&
            (!elems->awake_window || !le16_to_cpu(*elems->awake_window)))
                return;

        if (!test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
                for (ac = 0; ac < IEEE80211_NUM_ACS; ac++)
                        buffer_local += skb_queue_len(&sta->ps_tx_buf[ac]) +
                                        skb_queue_len(&sta->tx_filtered[ac]);

        if (!has_buffered && !buffer_local)
                return;

        if (sta->mesh->plink_state == NL80211_PLINK_ESTAB)
                mpsp_trigger_send(sta, has_buffered, !buffer_local);
        else
                mps_frame_deliver(sta, 1);
}