/*
 * Copyright 2004, Instant802 Networks, 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 <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"

/* maximum number of hardware queues we support. */
#define TC_80211_MAX_QUEUES 8

struct ieee80211_sched_data
{
        struct tcf_proto *filter_list;
        struct Qdisc *queues[TC_80211_MAX_QUEUES];
        struct sk_buff_head requeued[TC_80211_MAX_QUEUES];
};


/* given a data frame determine the 802.1p/1d tag to use */
static inline unsigned classify_1d(struct sk_buff *skb, struct Qdisc *qd)
{
        struct iphdr *ip;
        int dscp;
        int offset;

        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct tcf_result res = { -1, 0 };

        /* if there is a user set filter list, call out to that */
        if (q->filter_list) {
                tc_classify(skb, q->filter_list, &res);
                if (res.class != -1)
                        return res.class;
        }

        /* skb->priority values from 256->263 are magic values to
         * directly indicate a specific 802.1d priority.
         * This is used to allow 802.1d priority to be passed directly in
         * from VLAN tags, etc. */
        if (skb->priority >= 256 && skb->priority <= 263)
                return skb->priority - 256;

        /* check there is a valid IP header present */
        offset = ieee80211_get_hdrlen_from_skb(skb) + 8 /* LLC + proto */;
        if (skb->protocol != __constant_htons(ETH_P_IP) ||
            skb->len < offset + sizeof(*ip))
                return 0;

        ip = (struct iphdr *) (skb->data + offset);

        dscp = ip->tos & 0xfc;
        if (dscp & 0x1c)
                return 0;
        return dscp >> 5;
}


static inline 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;
        }
}


/* positive return value indicates which queue to use
 * negative return value indicates to drop the frame */
static inline int classify80211(struct sk_buff *skb, struct Qdisc *qd)
{
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        unsigned short fc = le16_to_cpu(hdr->frame_control);
        int qos;
        const int ieee802_1d_to_ac[8] = { 2, 3, 3, 2, 1, 1, 0, 0 };

        /* see if frame is data or non data frame */
        if (unlikely((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA)) {
                /* management frames go on AC_VO queue, but are sent
                * without QoS control fields */
                return IEEE80211_TX_QUEUE_DATA0;
        }

        if (0 /* injected */) {
                /* use AC from radiotap */
        }

        /* is this a QoS frame? */
        qos = fc & IEEE80211_STYPE_QOS_DATA;

        if (!qos) {
                skb->priority = 0; /* required for correct WPA/11i MIC */
                return ieee802_1d_to_ac[skb->priority];
        }

        /* use the data classifier to determine what 802.1d tag the
         * data frame has */
        skb->priority = classify_1d(skb, qd);

        /* in case we are a client verify acm is not set for this ac */
        while (unlikely(local->wmm_acm & BIT(skb->priority))) {
                if (wme_downgrade_ac(skb)) {
                        /* No AC with lower priority has acm=0, drop packet. */
                        return -1;
                }
        }

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


static int wme_qdiscop_enqueue(struct sk_buff *skb, struct Qdisc* qd)
{
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_tx_packet_data *pkt_data =
                (struct ieee80211_tx_packet_data *) skb->cb;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        unsigned short fc = le16_to_cpu(hdr->frame_control);
        struct Qdisc *qdisc;
        int err, queue;

        if (pkt_data->flags & IEEE80211_TXPD_REQUEUE) {
                skb_queue_tail(&q->requeued[pkt_data->queue], skb);
                qd->q.qlen++;
                return 0;
        }

        queue = classify80211(skb, qd);

        /* now we know the 1d priority, fill in the QoS header if there is one
         */
        if (WLAN_FC_IS_QOS_DATA(fc)) {
                u8 *p = skb->data + ieee80211_get_hdrlen(fc) - 2;
                u8 qos_hdr = skb->priority & QOS_CONTROL_TAG1D_MASK;
                if (local->wifi_wme_noack_test)
                        qos_hdr |= QOS_CONTROL_ACK_POLICY_NOACK <<
                                        QOS_CONTROL_ACK_POLICY_SHIFT;
                /* qos header is 2 bytes, second reserved */
                *p = qos_hdr;
                p++;
                *p = 0;
        }

        if (unlikely(queue >= local->hw.queues)) {
#if 0
                if (net_ratelimit()) {
                        printk(KERN_DEBUG "%s - queue=%d (hw does not "
                               "support) -> %d\n",
                               __func__, queue, local->hw.queues - 1);
                }
#endif
                queue = local->hw.queues - 1;
        }

        if (unlikely(queue < 0)) {
                        kfree_skb(skb);
                        err = NET_XMIT_DROP;
        } else {
                pkt_data->queue = (unsigned int) queue;
                qdisc = q->queues[queue];
                err = qdisc->enqueue(skb, qdisc);
                if (err == NET_XMIT_SUCCESS) {
                        qd->q.qlen++;
                        qd->bstats.bytes += skb->len;
                        qd->bstats.packets++;
                        return NET_XMIT_SUCCESS;
                }
        }
        qd->qstats.drops++;
        return err;
}


/* TODO: clean up the cases where master_hard_start_xmit
 * returns non 0 - it shouldn't ever do that. Once done we
 * can remove this function */
static int wme_qdiscop_requeue(struct sk_buff *skb, struct Qdisc* qd)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_tx_packet_data *pkt_data =
                (struct ieee80211_tx_packet_data *) skb->cb;
        struct Qdisc *qdisc;
        int err;

        /* we recorded which queue to use earlier! */
        qdisc = q->queues[pkt_data->queue];

        if ((err = qdisc->ops->requeue(skb, qdisc)) == 0) {
                qd->q.qlen++;
                return 0;
        }
        qd->qstats.drops++;
        return err;
}


static struct sk_buff *wme_qdiscop_dequeue(struct Qdisc* qd)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct net_device *dev = qd->dev;
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        struct sk_buff *skb;
        struct Qdisc *qdisc;
        int queue;

        /* check all the h/w queues in numeric/priority order */
        for (queue = 0; queue < hw->queues; queue++) {
                /* see if there is room in this hardware queue */
                if (test_bit(IEEE80211_LINK_STATE_XOFF,
                             &local->state[queue]) ||
                    test_bit(IEEE80211_LINK_STATE_PENDING,
                             &local->state[queue]))
                        continue;

                /* there is space - try and get a frame */
                skb = skb_dequeue(&q->requeued[queue]);
                if (skb) {
                        qd->q.qlen--;
                        return skb;
                }

                qdisc = q->queues[queue];
                skb = qdisc->dequeue(qdisc);
                if (skb) {
                        qd->q.qlen--;
                        return skb;
                }
        }
        /* returning a NULL here when all the h/w queues are full means we
         * never need to call netif_stop_queue in the driver */
        return NULL;
}


static void wme_qdiscop_reset(struct Qdisc* qd)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        int queue;

        /* QUESTION: should we have some hardware flush functionality here? */

        for (queue = 0; queue < hw->queues; queue++) {
                skb_queue_purge(&q->requeued[queue]);
                qdisc_reset(q->queues[queue]);
        }
        qd->q.qlen = 0;
}


static void wme_qdiscop_destroy(struct Qdisc* qd)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        int queue;

        tcf_destroy_chain(q->filter_list);
        q->filter_list = NULL;

        for (queue=0; queue < hw->queues; queue++) {
                skb_queue_purge(&q->requeued[queue]);
                qdisc_destroy(q->queues[queue]);
                q->queues[queue] = &noop_qdisc;
        }
}


/* called whenever parameters are updated on existing qdisc */
static int wme_qdiscop_tune(struct Qdisc *qd, struct rtattr *opt)
{
/*      struct ieee80211_sched_data *q = qdisc_priv(qd);
*/
        /* check our options block is the right size */
        /* copy any options to our local structure */
/*      Ignore options block for now - always use static mapping
        struct tc_ieee80211_qopt *qopt = RTA_DATA(opt);

        if (opt->rta_len < RTA_LENGTH(sizeof(*qopt)))
                return -EINVAL;
        memcpy(q->tag2queue, qopt->tag2queue, sizeof(qopt->tag2queue));
*/
        return 0;
}


/* called during initial creation of qdisc on device */
static int wme_qdiscop_init(struct Qdisc *qd, struct rtattr *opt)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct net_device *dev = qd->dev;
        struct ieee80211_local *local;
        int queues;
        int err = 0, i;

        /* check that device is a mac80211 device */
        if (!dev->ieee80211_ptr ||
            dev->ieee80211_ptr->wiphy->privid != mac80211_wiphy_privid)
                return -EINVAL;

        /* check this device is an ieee80211 master type device */
        if (dev->type != ARPHRD_IEEE80211)
                return -EINVAL;

        /* check that there is no qdisc currently attached to device
         * this ensures that we will be the root qdisc. (I can't find a better
         * way to test this explicitly) */
        if (dev->qdisc_sleeping != &noop_qdisc)
                return -EINVAL;

        if (qd->flags & TCQ_F_INGRESS)
                return -EINVAL;

        local = wdev_priv(dev->ieee80211_ptr);
        queues = local->hw.queues;

        /* if options were passed in, set them */
        if (opt) {
                err = wme_qdiscop_tune(qd, opt);
        }

        /* create child queues */
        for (i = 0; i < queues; i++) {
                skb_queue_head_init(&q->requeued[i]);
                q->queues[i] = qdisc_create_dflt(qd->dev, &pfifo_qdisc_ops,
                                                 qd->handle);
                if (!q->queues[i]) {
                        q->queues[i] = &noop_qdisc;
                        printk(KERN_ERR "%s child qdisc %i creation failed", dev->name, i);
                }
        }

        return err;
}

static int wme_qdiscop_dump(struct Qdisc *qd, struct sk_buff *skb)
{
/*      struct ieee80211_sched_data *q = qdisc_priv(qd);
        unsigned char *p = skb->tail;
        struct tc_ieee80211_qopt opt;

        memcpy(&opt.tag2queue, q->tag2queue, TC_80211_MAX_TAG + 1);
        RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
*/      return skb->len;
/*
rtattr_failure:
        skb_trim(skb, p - skb->data);*/
        return -1;
}


static int wme_classop_graft(struct Qdisc *qd, unsigned long arg,
                             struct Qdisc *new, struct Qdisc **old)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        unsigned long queue = arg - 1;

        if (queue >= hw->queues)
                return -EINVAL;

        if (!new)
                new = &noop_qdisc;

        sch_tree_lock(qd);
        *old = q->queues[queue];
        q->queues[queue] = new;
        qdisc_reset(*old);
        sch_tree_unlock(qd);

        return 0;
}


static struct Qdisc *
wme_classop_leaf(struct Qdisc *qd, unsigned long arg)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        unsigned long queue = arg - 1;

        if (queue >= hw->queues)
                return NULL;

        return q->queues[queue];
}


static unsigned long wme_classop_get(struct Qdisc *qd, u32 classid)
{
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        unsigned long queue = TC_H_MIN(classid);

        if (queue - 1 >= hw->queues)
                return 0;

        return queue;
}


static unsigned long wme_classop_bind(struct Qdisc *qd, unsigned long parent,
                                      u32 classid)
{
        return wme_classop_get(qd, classid);
}


static void wme_classop_put(struct Qdisc *q, unsigned long cl)
{
}


static int wme_classop_change(struct Qdisc *qd, u32 handle, u32 parent,
                              struct rtattr **tca, unsigned long *arg)
{
        unsigned long cl = *arg;
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;

        if (cl - 1 > hw->queues)
                return -ENOENT;

        /* TODO: put code to program hardware queue parameters here,
         * to allow programming from tc command line */

        return 0;
}


/* we don't support deleting hardware queues
 * when we add WMM-SA support - TSPECs may be deleted here */
static int wme_classop_delete(struct Qdisc *qd, unsigned long cl)
{
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;

        if (cl - 1 > hw->queues)
                return -ENOENT;
        return 0;
}


static int wme_classop_dump_class(struct Qdisc *qd, unsigned long cl,
                                  struct sk_buff *skb, struct tcmsg *tcm)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;

        if (cl - 1 > hw->queues)
                return -ENOENT;
        tcm->tcm_handle = TC_H_MIN(cl);
        tcm->tcm_parent = qd->handle;
        tcm->tcm_info = q->queues[cl-1]->handle; /* do we need this? */
        return 0;
}


static void wme_classop_walk(struct Qdisc *qd, struct qdisc_walker *arg)
{
        struct ieee80211_local *local = wdev_priv(qd->dev->ieee80211_ptr);
        struct ieee80211_hw *hw = &local->hw;
        int queue;

        if (arg->stop)
                return;

        for (queue = 0; queue < hw->queues; queue++) {
                if (arg->count < arg->skip) {
                        arg->count++;
                        continue;
                }
                /* we should return classids for our internal queues here
                 * as well as the external ones */
                if (arg->fn(qd, queue+1, arg) < 0) {
                        arg->stop = 1;
                        break;
                }
                arg->count++;
        }
}


static struct tcf_proto ** wme_classop_find_tcf(struct Qdisc *qd,
                                                unsigned long cl)
{
        struct ieee80211_sched_data *q = qdisc_priv(qd);

        if (cl)
                return NULL;

        return &q->filter_list;
}


/* this qdisc is classful (i.e. has classes, some of which may have leaf qdiscs attached)
 * - these are the operations on the classes */
static struct Qdisc_class_ops class_ops =
{
        .graft = wme_classop_graft,
        .leaf = wme_classop_leaf,

        .get = wme_classop_get,
        .put = wme_classop_put,
        .change = wme_classop_change,
        .delete = wme_classop_delete,
        .walk = wme_classop_walk,

        .tcf_chain = wme_classop_find_tcf,
        .bind_tcf = wme_classop_bind,
        .unbind_tcf = wme_classop_put,

        .dump = wme_classop_dump_class,
};


/* queueing discipline operations */
static struct Qdisc_ops wme_qdisc_ops =
{
        .next = NULL,
        .cl_ops = &class_ops,
        .id = "ieee80211",
        .priv_size = sizeof(struct ieee80211_sched_data),

        .enqueue = wme_qdiscop_enqueue,
        .dequeue = wme_qdiscop_dequeue,
        .requeue = wme_qdiscop_requeue,
        .drop = NULL, /* drop not needed since we are always the root qdisc */

        .init = wme_qdiscop_init,
        .reset = wme_qdiscop_reset,
        .destroy = wme_qdiscop_destroy,
        .change = wme_qdiscop_tune,

        .dump = wme_qdiscop_dump,
};


void ieee80211_install_qdisc(struct net_device *dev)
{
        struct Qdisc *qdisc;

        qdisc = qdisc_create_dflt(dev, &wme_qdisc_ops, TC_H_ROOT);
        if (!qdisc) {
                printk(KERN_ERR "%s: qdisc installation failed\n", dev->name);
                return;
        }

        /* same handle as would be allocated by qdisc_alloc_handle() */
        qdisc->handle = 0x80010000;

        qdisc_lock_tree(dev);
        list_add_tail(&qdisc->list, &dev->qdisc_list);
        dev->qdisc_sleeping = qdisc;
        qdisc_unlock_tree(dev);
}


int ieee80211_qdisc_installed(struct net_device *dev)
{
        return dev->qdisc_sleeping->ops == &wme_qdisc_ops;
}


int ieee80211_wme_register(void)
{
        return register_qdisc(&wme_qdisc_ops);
}


void ieee80211_wme_unregister(void)
{
        unregister_qdisc(&wme_qdisc_ops);
}