/*
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2013-2014  Intel Mobile Communications GmbH
 *
 * 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/netdevice.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/types.h>
#include <net/ip.h>
#include <net/pkt_sched.h>

#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "wme.h"

/* Default mapping in classifier to work with default
 * queue setup.
 */
const int ieee802_1d_to_ac[8] = {
        IEEE80211_AC_BE,
        IEEE80211_AC_BK,
        IEEE80211_AC_BK,
        IEEE80211_AC_BE,
        IEEE80211_AC_VI,
        IEEE80211_AC_VI,
        IEEE80211_AC_VO,
        IEEE80211_AC_VO
};

static int wme_downgrade_ac(struct sk_buff *skb)
{
        switch (skb->priority) {
        case 6:
        case 7:
                skb->priority = 5; /* VO -> VI */
                return 0;
        case 4:
        case 5:
                skb->priority = 3; /* VI -> BE */
                return 0;
        case 0:
        case 3:
                skb->priority = 2; /* BE -> BK */
                return 0;
        default:
                return -1;
        }
}

/**
 * ieee80211_fix_reserved_tid - return the TID to use if this one is reserved
 * @tid: the assumed-reserved TID
 *
 * Returns: the alternative TID to use, or 0 on error
 */
static inline u8 ieee80211_fix_reserved_tid(u8 tid)
{
        switch (tid) {
        case 0:
                return 3;
        case 1:
                return 2;
        case 2:
                return 1;
        case 3:
                return 0;
        case 4:
                return 5;
        case 5:
                return 4;
        case 6:
                return 7;
        case 7:
                return 6;
        }

        return 0;
}

static u16 ieee80211_downgrade_queue(struct ieee80211_sub_if_data *sdata,
                                     struct sta_info *sta, struct sk_buff *skb)
{
        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;

        /* in case we are a client verify acm is not set for this ac */
        while (sdata->wmm_acm & BIT(skb->priority)) {
                int ac = ieee802_1d_to_ac[skb->priority];

                if (ifmgd->tx_tspec[ac].admitted_time &&
                    skb->priority == ifmgd->tx_tspec[ac].up)
                        return ac;

                if (wme_downgrade_ac(skb)) {
                        /*
                         * This should not really happen. The AP has marked all
                         * lower ACs to require admission control which is not
                         * a reasonable configuration. Allow the frame to be
                         * transmitted using AC_BK as a workaround.
                         */
                        break;
                }
        }

        /* Check to see if this is a reserved TID */
        if (sta && sta->reserved_tid == skb->priority)
                skb->priority = ieee80211_fix_reserved_tid(skb->priority);

        /* look up which queue to use for frames with this 1d tag */
        return ieee802_1d_to_ac[skb->priority];
}

/* Indicate which queue to use for this fully formed 802.11 frame */
u16 ieee80211_select_queue_80211(struct ieee80211_sub_if_data *sdata,
                                 struct sk_buff *skb,
                                 struct ieee80211_hdr *hdr)
{
        struct ieee80211_local *local = sdata->local;
        u8 *p;

        if (local->hw.queues < IEEE80211_NUM_ACS)
                return 0;

        if (!ieee80211_is_data(hdr->frame_control)) {
                skb->priority = 7;
                return ieee802_1d_to_ac[skb->priority];
        }
        if (!ieee80211_is_data_qos(hdr->frame_control)) {
                skb->priority = 0;
                return ieee802_1d_to_ac[skb->priority];
        }

        p = ieee80211_get_qos_ctl(hdr);
        skb->priority = *p & IEEE80211_QOS_CTL_TAG1D_MASK;

        return ieee80211_downgrade_queue(sdata, NULL, skb);
}

/* Indicate which queue to use. */
u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
                           struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta = NULL;
        const u8 *ra = NULL;
        bool qos = false;
        struct mac80211_qos_map *qos_map;
        u16 ret;

        if (local->hw.queues < IEEE80211_NUM_ACS || skb->len < 6) {
                skb->priority = 0; /* required for correct WPA/11i MIC */
                return 0;
        }

        rcu_read_lock();
        switch (sdata->vif.type) {
        case NL80211_IFTYPE_AP_VLAN:
                sta = rcu_dereference(sdata->u.vlan.sta);
                if (sta) {
                        qos = sta->sta.wme;
                        break;
                }
        case NL80211_IFTYPE_AP:
                ra = skb->data;
                break;
        case NL80211_IFTYPE_WDS:
                ra = sdata->u.wds.remote_addr;
                break;
#ifdef CONFIG_MAC80211_MESH
        case NL80211_IFTYPE_MESH_POINT:
                qos = true;
                break;
#endif
        case NL80211_IFTYPE_STATION:
                /* might be a TDLS station */
                sta = sta_info_get(sdata, skb->data);
                if (sta)
                        qos = sta->sta.wme;

                ra = sdata->u.mgd.bssid;
                break;
        case NL80211_IFTYPE_ADHOC:
                ra = skb->data;
                break;
        case NL80211_IFTYPE_OCB:
                /* all stations are required to support WME */
                qos = true;
                break;
        default:
                break;
        }

        if (!sta && ra && !is_multicast_ether_addr(ra)) {
                sta = sta_info_get(sdata, ra);
                if (sta)
                        qos = sta->sta.wme;
        }

        if (!qos) {
                skb->priority = 0; /* required for correct WPA/11i MIC */
                ret = IEEE80211_AC_BE;
                goto out;
        }

        if (skb->protocol == sdata->control_port_protocol) {
                skb->priority = 7;
                goto downgrade;
        }

        /* use the data classifier to determine what 802.1d tag the
         * data frame has */
        qos_map = rcu_dereference(sdata->qos_map);
        skb->priority = cfg80211_classify8021d(skb, qos_map ?
                                               &qos_map->qos_map : NULL);

 downgrade:
        ret = ieee80211_downgrade_queue(sdata, sta, skb);
 out:
        rcu_read_unlock();
        return ret;
}

/**
 * ieee80211_set_qos_hdr - Fill in the QoS header if there is one.
 *
 * @sdata: local subif
 * @skb: packet to be updated
 */
void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,
                           struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr = (void *)skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        u8 *p;
        u8 ack_policy, tid;

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

        p = ieee80211_get_qos_ctl(hdr);
        tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;

        /* preserve EOSP bit */
        ack_policy = *p & IEEE80211_QOS_CTL_EOSP;

        if (is_multicast_ether_addr(hdr->addr1) ||
            sdata->noack_map & BIT(tid)) {
                ack_policy |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
                info->flags |= IEEE80211_TX_CTL_NO_ACK;
        }

        /* qos header is 2 bytes */
        *p++ = ack_policy | tid;
        if (ieee80211_vif_is_mesh(&sdata->vif)) {
                /* preserve RSPI and Mesh PS Level bit */
                *p &= ((IEEE80211_QOS_CTL_RSPI |
                        IEEE80211_QOS_CTL_MESH_PS_LEVEL) >> 8);

                /* Nulls don't have a mesh header (frame body) */
                if (!ieee80211_is_qos_nullfunc(hdr->frame_control))
                        *p |= (IEEE80211_QOS_CTL_MESH_CONTROL_PRESENT >> 8);
        } else {
                *p = 0;
        }
}