/*
 * HT handling
 *
 * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 * Copyright 2007-2010, Intel Corporation
 * Copyright(c) 2015-2017 Intel Deutschland GmbH
 * Copyright (C) 2018        Intel Corporation
 *
 * 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.
 */

/**
 * DOC: RX A-MPDU aggregation
 *
 * Aggregation on the RX side requires only implementing the
 * @ampdu_action callback that is invoked to start/stop any
 * block-ack sessions for RX aggregation.
 *
 * When RX aggregation is started by the peer, the driver is
 * notified via @ampdu_action function, with the
 * %IEEE80211_AMPDU_RX_START action, and may reject the request
 * in which case a negative response is sent to the peer, if it
 * accepts it a positive response is sent.
 *
 * While the session is active, the device/driver are required
 * to de-aggregate frames and pass them up one by one to mac80211,
 * which will handle the reorder buffer.
 *
 * When the aggregation session is stopped again by the peer or
 * ourselves, the driver's @ampdu_action function will be called
 * with the action %IEEE80211_AMPDU_RX_STOP. In this case, the
 * call must not fail.
 */

#include <linux/ieee80211.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.h"

static void ieee80211_free_tid_rx(struct rcu_head *h)
{
        struct tid_ampdu_rx *tid_rx =
                container_of(h, struct tid_ampdu_rx, rcu_head);
        int i;

        for (i = 0; i < tid_rx->buf_size; i++)
                __skb_queue_purge(&tid_rx->reorder_buf[i]);
        kfree(tid_rx->reorder_buf);
        kfree(tid_rx->reorder_time);
        kfree(tid_rx);
}

void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
                                     u16 initiator, u16 reason, bool tx)
{
        struct ieee80211_local *local = sta->local;
        struct tid_ampdu_rx *tid_rx;
        struct ieee80211_ampdu_params params = {
                .sta = &sta->sta,
                .action = IEEE80211_AMPDU_RX_STOP,
                .tid = tid,
                .amsdu = false,
                .timeout = 0,
                .ssn = 0,
        };

        lockdep_assert_held(&sta->ampdu_mlme.mtx);

        tid_rx = rcu_dereference_protected(sta->ampdu_mlme.tid_rx[tid],
                                        lockdep_is_held(&sta->ampdu_mlme.mtx));

        if (!test_bit(tid, sta->ampdu_mlme.agg_session_valid))
                return;

        RCU_INIT_POINTER(sta->ampdu_mlme.tid_rx[tid], NULL);
        __clear_bit(tid, sta->ampdu_mlme.agg_session_valid);

        ht_dbg(sta->sdata,
               "Rx BA session stop requested for %pM tid %u %s reason: %d\n",
               sta->sta.addr, tid,
               initiator == WLAN_BACK_RECIPIENT ? "recipient" : "initiator",
               (int)reason);

        if (drv_ampdu_action(local, sta->sdata, &params))
                sdata_info(sta->sdata,
                           "HW problem - can not stop rx aggregation for %pM tid %d\n",
                           sta->sta.addr, tid);

        /* check if this is a self generated aggregation halt */
        if (initiator == WLAN_BACK_RECIPIENT && tx)
                ieee80211_send_delba(sta->sdata, sta->sta.addr,
                                     tid, WLAN_BACK_RECIPIENT, reason);

        /*
         * return here in case tid_rx is not assigned - which will happen if
         * IEEE80211_HW_SUPPORTS_REORDERING_BUFFER is set.
         */
        if (!tid_rx)
                return;

        del_timer_sync(&tid_rx->session_timer);

        /* make sure ieee80211_sta_reorder_release() doesn't re-arm the timer */
        spin_lock_bh(&tid_rx->reorder_lock);
        tid_rx->removed = true;
        spin_unlock_bh(&tid_rx->reorder_lock);
        del_timer_sync(&tid_rx->reorder_timer);

        call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
}

void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
                                    u16 initiator, u16 reason, bool tx)
{
        mutex_lock(&sta->ampdu_mlme.mtx);
        ___ieee80211_stop_rx_ba_session(sta, tid, initiator, reason, tx);
        mutex_unlock(&sta->ampdu_mlme.mtx);
}

void ieee80211_stop_rx_ba_session(struct ieee80211_vif *vif, u16 ba_rx_bitmap,
                                  const u8 *addr)
{
        struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
        struct sta_info *sta;
        int i;

        rcu_read_lock();
        sta = sta_info_get_bss(sdata, addr);
        if (!sta) {
                rcu_read_unlock();
                return;
        }

        for (i = 0; i < IEEE80211_NUM_TIDS; i++)
                if (ba_rx_bitmap & BIT(i))
                        set_bit(i, sta->ampdu_mlme.tid_rx_stop_requested);

        ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
        rcu_read_unlock();
}
EXPORT_SYMBOL(ieee80211_stop_rx_ba_session);

/*
 * After accepting the AddBA Request we activated a timer,
 * resetting it after each frame that arrives from the originator.
 */
static void sta_rx_agg_session_timer_expired(struct timer_list *t)
{
        struct tid_ampdu_rx *tid_rx = from_timer(tid_rx, t, session_timer);
        struct sta_info *sta = tid_rx->sta;
        u8 tid = tid_rx->tid;
        unsigned long timeout;

        timeout = tid_rx->last_rx + TU_TO_JIFFIES(tid_rx->timeout);
        if (time_is_after_jiffies(timeout)) {
                mod_timer(&tid_rx->session_timer, timeout);
                return;
        }

        ht_dbg(sta->sdata, "RX session timer expired on %pM tid %d\n",
               sta->sta.addr, tid);

        set_bit(tid, sta->ampdu_mlme.tid_rx_timer_expired);
        ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
}

static void sta_rx_agg_reorder_timer_expired(struct timer_list *t)
{
        struct tid_ampdu_rx *tid_rx = from_timer(tid_rx, t, reorder_timer);

        rcu_read_lock();
        ieee80211_release_reorder_timeout(tid_rx->sta, tid_rx->tid);
        rcu_read_unlock();
}

static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *da, u16 tid,
                                      u8 dialog_token, u16 status, u16 policy,
                                      u16 buf_size, u16 timeout)
{
        struct ieee80211_local *local = sdata->local;
        struct sk_buff *skb;
        struct ieee80211_mgmt *mgmt;
        bool amsdu = ieee80211_hw_check(&local->hw, SUPPORTS_AMSDU_IN_AMPDU);
        u16 capab;

        skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
        if (!skb)
                return;

        skb_reserve(skb, local->hw.extra_tx_headroom);
        mgmt = skb_put_zero(skb, 24);
        memcpy(mgmt->da, da, ETH_ALEN);
        memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
        if (sdata->vif.type == NL80211_IFTYPE_AP ||
            sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
            sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
                memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
        else if (sdata->vif.type == NL80211_IFTYPE_STATION)
                memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);
        else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
                memcpy(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN);

        mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                          IEEE80211_STYPE_ACTION);

        skb_put(skb, 1 + sizeof(mgmt->u.action.u.addba_resp));
        mgmt->u.action.category = WLAN_CATEGORY_BACK;
        mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
        mgmt->u.action.u.addba_resp.dialog_token = dialog_token;

        capab = (u16)(amsdu << 0);      /* bit 0 A-MSDU support */
        capab |= (u16)(policy << 1);    /* bit 1 aggregation policy */
        capab |= (u16)(tid << 2);       /* bit 5:2 TID number */
        capab |= (u16)(buf_size << 6);  /* bit 15:6 max size of aggregation */

        mgmt->u.action.u.addba_resp.capab = cpu_to_le16(capab);
        mgmt->u.action.u.addba_resp.timeout = cpu_to_le16(timeout);
        mgmt->u.action.u.addba_resp.status = cpu_to_le16(status);

        ieee80211_tx_skb(sdata, skb);
}

void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
                                      u8 dialog_token, u16 timeout,
                                      u16 start_seq_num, u16 ba_policy, u16 tid,
                                      u16 buf_size, bool tx, bool auto_seq)
{
        struct ieee80211_local *local = sta->sdata->local;
        struct tid_ampdu_rx *tid_agg_rx;
        struct ieee80211_ampdu_params params = {
                .sta = &sta->sta,
                .action = IEEE80211_AMPDU_RX_START,
                .tid = tid,
                .amsdu = false,
                .timeout = timeout,
                .ssn = start_seq_num,
        };
        int i, ret = -EOPNOTSUPP;
        u16 status = WLAN_STATUS_REQUEST_DECLINED;

        if (tid >= IEEE80211_FIRST_TSPEC_TSID) {
                ht_dbg(sta->sdata,
                       "STA %pM requests BA session on unsupported tid %d\n",
                       sta->sta.addr, tid);
                goto end;
        }

        if (!sta->sta.ht_cap.ht_supported) {
                ht_dbg(sta->sdata,
                       "STA %pM erroneously requests BA session on tid %d w/o QoS\n",
                       sta->sta.addr, tid);
                /* send a response anyway, it's an error case if we get here */
                goto end;
        }

        if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
                ht_dbg(sta->sdata,
                       "Suspend in progress - Denying ADDBA request (%pM tid %d)\n",
                       sta->sta.addr, tid);
                goto end;
        }

        /* sanity check for incoming parameters:
         * check if configuration can support the BA policy
         * and if buffer size does not exceeds max value */
        /* XXX: check own ht delayed BA capability?? */
        if (((ba_policy != 1) &&
             (!(sta->sta.ht_cap.cap & IEEE80211_HT_CAP_DELAY_BA))) ||
            (buf_size > IEEE80211_MAX_AMPDU_BUF)) {
                status = WLAN_STATUS_INVALID_QOS_PARAM;
                ht_dbg_ratelimited(sta->sdata,
                                   "AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d\n",
                                   sta->sta.addr, tid, ba_policy, buf_size);
                goto end;
        }
        /* determine default buffer size */
        if (buf_size == 0)
                buf_size = IEEE80211_MAX_AMPDU_BUF;

        /* make sure the size doesn't exceed the maximum supported by the hw */
        if (buf_size > sta->sta.max_rx_aggregation_subframes)
                buf_size = sta->sta.max_rx_aggregation_subframes;
        params.buf_size = buf_size;

        ht_dbg(sta->sdata, "AddBA Req buf_size=%d for %pM\n",
               buf_size, sta->sta.addr);

        /* examine state machine */
        lockdep_assert_held(&sta->ampdu_mlme.mtx);

        if (test_bit(tid, sta->ampdu_mlme.agg_session_valid)) {
                if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) {
                        struct tid_ampdu_rx *tid_rx;

                        ht_dbg_ratelimited(sta->sdata,
                                           "updated AddBA Req from %pM on tid %u\n",
                                           sta->sta.addr, tid);
                        /* We have no API to update the timeout value in the
                         * driver so reject the timeout update if the timeout
                         * changed. If if did not change, i.e., no real update,
                         * just reply with success.
                         */
                        rcu_read_lock();
                        tid_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
                        if (tid_rx && tid_rx->timeout == timeout)
                                status = WLAN_STATUS_SUCCESS;
                        else
                                status = WLAN_STATUS_REQUEST_DECLINED;
                        rcu_read_unlock();
                        goto end;
                }

                ht_dbg_ratelimited(sta->sdata,
                                   "unexpected AddBA Req from %pM on tid %u\n",
                                   sta->sta.addr, tid);

                /* delete existing Rx BA session on the same tid */
                ___ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_RECIPIENT,
                                                WLAN_STATUS_UNSPECIFIED_QOS,
                                                false);
        }

        if (ieee80211_hw_check(&local->hw, SUPPORTS_REORDERING_BUFFER)) {
                ret = drv_ampdu_action(local, sta->sdata, &params);
                ht_dbg(sta->sdata,
                       "Rx A-MPDU request on %pM tid %d result %d\n",
                       sta->sta.addr, tid, ret);
                if (!ret)
                        status = WLAN_STATUS_SUCCESS;
                goto end;
        }

        /* prepare A-MPDU MLME for Rx aggregation */
        tid_agg_rx = kzalloc(sizeof(*tid_agg_rx), GFP_KERNEL);
        if (!tid_agg_rx)
                goto end;

        spin_lock_init(&tid_agg_rx->reorder_lock);

        /* rx timer */
        timer_setup(&tid_agg_rx->session_timer,
                    sta_rx_agg_session_timer_expired, TIMER_DEFERRABLE);

        /* rx reorder timer */
        timer_setup(&tid_agg_rx->reorder_timer,
                    sta_rx_agg_reorder_timer_expired, 0);

        /* prepare reordering buffer */
        tid_agg_rx->reorder_buf =
                kcalloc(buf_size, sizeof(struct sk_buff_head), GFP_KERNEL);
        tid_agg_rx->reorder_time =
                kcalloc(buf_size, sizeof(unsigned long), GFP_KERNEL);
        if (!tid_agg_rx->reorder_buf || !tid_agg_rx->reorder_time) {
                kfree(tid_agg_rx->reorder_buf);
                kfree(tid_agg_rx->reorder_time);
                kfree(tid_agg_rx);
                goto end;
        }

        for (i = 0; i < buf_size; i++)
                __skb_queue_head_init(&tid_agg_rx->reorder_buf[i]);

        ret = drv_ampdu_action(local, sta->sdata, &params);
        ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d\n",
               sta->sta.addr, tid, ret);
        if (ret) {
                kfree(tid_agg_rx->reorder_buf);
                kfree(tid_agg_rx->reorder_time);
                kfree(tid_agg_rx);
                goto end;
        }

        /* update data */
        tid_agg_rx->ssn = start_seq_num;
        tid_agg_rx->head_seq_num = start_seq_num;
        tid_agg_rx->buf_size = buf_size;
        tid_agg_rx->timeout = timeout;
        tid_agg_rx->stored_mpdu_num = 0;
        tid_agg_rx->auto_seq = auto_seq;
        tid_agg_rx->started = false;
        tid_agg_rx->reorder_buf_filtered = 0;
        tid_agg_rx->tid = tid;
        tid_agg_rx->sta = sta;
        status = WLAN_STATUS_SUCCESS;

        /* activate it for RX */
        rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx);

        if (timeout) {
                mod_timer(&tid_agg_rx->session_timer, TU_TO_EXP_TIME(timeout));
                tid_agg_rx->last_rx = jiffies;
        }

end:
        if (status == WLAN_STATUS_SUCCESS) {
                __set_bit(tid, sta->ampdu_mlme.agg_session_valid);
                __clear_bit(tid, sta->ampdu_mlme.unexpected_agg);
                sta->ampdu_mlme.tid_rx_token[tid] = dialog_token;
        }

        if (tx)
                ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
                                          dialog_token, status, 1, buf_size,
                                          timeout);
}

static void __ieee80211_start_rx_ba_session(struct sta_info *sta,
                                            u8 dialog_token, u16 timeout,
                                            u16 start_seq_num, u16 ba_policy,
                                            u16 tid, u16 buf_size, bool tx,
                                            bool auto_seq)
{
        mutex_lock(&sta->ampdu_mlme.mtx);
        ___ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
                                         start_seq_num, ba_policy, tid,
                                         buf_size, tx, auto_seq);
        mutex_unlock(&sta->ampdu_mlme.mtx);
}

void ieee80211_process_addba_request(struct ieee80211_local *local,
                                     struct sta_info *sta,
                                     struct ieee80211_mgmt *mgmt,
                                     size_t len)
{
        u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num;
        u8 dialog_token;

        /* extract session parameters from addba request frame */
        dialog_token = mgmt->u.action.u.addba_req.dialog_token;
        timeout = le16_to_cpu(mgmt->u.action.u.addba_req.timeout);
        start_seq_num =
                le16_to_cpu(mgmt->u.action.u.addba_req.start_seq_num) >> 4;

        capab = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
        ba_policy = (capab & IEEE80211_ADDBA_PARAM_POLICY_MASK) >> 1;
        tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
        buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;

        __ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
                                        start_seq_num, ba_policy, tid,
                                        buf_size, true, false);
}

void ieee80211_manage_rx_ba_offl(struct ieee80211_vif *vif,
                                 const u8 *addr, unsigned int tid)
{
        struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;

        rcu_read_lock();
        sta = sta_info_get_bss(sdata, addr);
        if (!sta)
                goto unlock;

        set_bit(tid, sta->ampdu_mlme.tid_rx_manage_offl);
        ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
 unlock:
        rcu_read_unlock();
}
EXPORT_SYMBOL(ieee80211_manage_rx_ba_offl);

void ieee80211_rx_ba_timer_expired(struct ieee80211_vif *vif,
                                   const u8 *addr, unsigned int tid)
{
        struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;

        rcu_read_lock();
        sta = sta_info_get_bss(sdata, addr);
        if (!sta)
                goto unlock;

        set_bit(tid, sta->ampdu_mlme.tid_rx_timer_expired);
        ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);

 unlock:
        rcu_read_unlock();
}
EXPORT_SYMBOL(ieee80211_rx_ba_timer_expired);