// SPDX-License-Identifier: ISC
/*
 * Copyright (c) 2014-2017 Qualcomm Atheros, Inc.
 * Copyright (c) 2018-2019, The Linux Foundation. All rights reserved.
 */

#include "wil6210.h"
#include "txrx.h"

#define SEQ_MODULO 0x1000
#define SEQ_MASK   0xfff

static inline int seq_less(u16 sq1, u16 sq2)
{
        return ((sq1 - sq2) & SEQ_MASK) > (SEQ_MODULO >> 1);
}

static inline u16 seq_inc(u16 sq)
{
        return (sq + 1) & SEQ_MASK;
}

static inline u16 seq_sub(u16 sq1, u16 sq2)
{
        return (sq1 - sq2) & SEQ_MASK;
}

static inline int reorder_index(struct wil_tid_ampdu_rx *r, u16 seq)
{
        return seq_sub(seq, r->ssn) % r->buf_size;
}

static void wil_release_reorder_frame(struct net_device *ndev,
                                      struct wil_tid_ampdu_rx *r,
                                      int index)
{
        struct sk_buff *skb = r->reorder_buf[index];

        if (!skb)
                goto no_frame;

        /* release the frame from the reorder ring buffer */
        r->stored_mpdu_num--;
        r->reorder_buf[index] = NULL;
        wil_netif_rx_any(skb, ndev);

no_frame:
        r->head_seq_num = seq_inc(r->head_seq_num);
}

static void wil_release_reorder_frames(struct net_device *ndev,
                                       struct wil_tid_ampdu_rx *r,
                                       u16 hseq)
{
        int index;

        /* note: this function is never called with
         * hseq preceding r->head_seq_num, i.e it is always true
         * !seq_less(hseq, r->head_seq_num)
         * and thus on loop exit it should be
         * r->head_seq_num == hseq
         */
        while (seq_less(r->head_seq_num, hseq) && r->stored_mpdu_num) {
                index = reorder_index(r, r->head_seq_num);
                wil_release_reorder_frame(ndev, r, index);
        }
        r->head_seq_num = hseq;
}

static void wil_reorder_release(struct net_device *ndev,
                                struct wil_tid_ampdu_rx *r)
{
        int index = reorder_index(r, r->head_seq_num);

        while (r->reorder_buf[index]) {
                wil_release_reorder_frame(ndev, r, index);
                index = reorder_index(r, r->head_seq_num);
        }
}

/* called in NAPI context */
void wil_rx_reorder(struct wil6210_priv *wil, struct sk_buff *skb)
__acquires(&sta->tid_rx_lock) __releases(&sta->tid_rx_lock)
{
        struct wil6210_vif *vif;
        struct net_device *ndev;
        int tid, cid, mid, mcast, retry;
        u16 seq;
        struct wil_sta_info *sta;
        struct wil_tid_ampdu_rx *r;
        u16 hseq;
        int index;

        wil->txrx_ops.get_reorder_params(wil, skb, &tid, &cid, &mid, &seq,
                                         &mcast, &retry);
        sta = &wil->sta[cid];

        wil_dbg_txrx(wil, "MID %d CID %d TID %d Seq 0x%03x mcast %01x\n",
                     mid, cid, tid, seq, mcast);

        vif = wil->vifs[mid];
        if (unlikely(!vif)) {
                wil_dbg_txrx(wil, "invalid VIF, mid %d\n", mid);
                dev_kfree_skb(skb);
                return;
        }
        ndev = vif_to_ndev(vif);

        spin_lock(&sta->tid_rx_lock);

        r = sta->tid_rx[tid];
        if (!r) {
                wil_netif_rx_any(skb, ndev);
                goto out;
        }

        if (unlikely(mcast)) {
                if (retry && seq == r->mcast_last_seq) {
                        r->drop_dup_mcast++;
                        wil_dbg_txrx(wil, "Rx drop: dup mcast seq 0x%03x\n",
                                     seq);
                        dev_kfree_skb(skb);
                        goto out;
                }
                r->mcast_last_seq = seq;
                wil_netif_rx_any(skb, ndev);
                goto out;
        }

        r->total++;
        hseq = r->head_seq_num;

        /** Due to the race between WMI events, where BACK establishment
         * reported, and data Rx, few packets may be pass up before reorder
         * buffer get allocated. Catch up by pretending SSN is what we
         * see in the 1-st Rx packet
         *
         * Another scenario, Rx get delayed and we got packet from before
         * BACK. Pass it to the stack and wait.
         */
        if (r->first_time) {
                r->first_time = false;
                if (seq != r->head_seq_num) {
                        if (seq_less(seq, r->head_seq_num)) {
                                wil_err(wil,
                                        "Error: frame with early sequence 0x%03x, should be 0x%03x. Waiting...\n",
                                        seq, r->head_seq_num);
                                r->first_time = true;
                                wil_netif_rx_any(skb, ndev);
                                goto out;
                        }
                        wil_err(wil,
                                "Error: 1-st frame with wrong sequence 0x%03x, should be 0x%03x. Fixing...\n",
                                seq, r->head_seq_num);
                        r->head_seq_num = seq;
                        r->ssn = seq;
                }
        }

        /* frame with out of date sequence number */
        if (seq_less(seq, r->head_seq_num)) {
                r->ssn_last_drop = seq;
                r->drop_old++;
                wil_dbg_txrx(wil, "Rx drop: old seq 0x%03x head 0x%03x\n",
                             seq, r->head_seq_num);
                dev_kfree_skb(skb);
                goto out;
        }

        /*
         * If frame the sequence number exceeds our buffering window
         * size release some previous frames to make room for this one.
         */
        if (!seq_less(seq, r->head_seq_num + r->buf_size)) {
                hseq = seq_inc(seq_sub(seq, r->buf_size));
                /* release stored frames up to new head to stack */
                wil_release_reorder_frames(ndev, r, hseq);
        }

        /* Now the new frame is always in the range of the reordering buffer */

        index = reorder_index(r, seq);

        /* check if we already stored this frame */
        if (r->reorder_buf[index]) {
                r->drop_dup++;
                wil_dbg_txrx(wil, "Rx drop: dup seq 0x%03x\n", seq);
                dev_kfree_skb(skb);
                goto out;
        }

        /*
         * If the current MPDU is in the right order and nothing else
         * is stored we can process it directly, no need to buffer it.
         * If it is first but there's something stored, we may be able
         * to release frames after this one.
         */
        if (seq == r->head_seq_num && r->stored_mpdu_num == 0) {
                r->head_seq_num = seq_inc(r->head_seq_num);
                wil_netif_rx_any(skb, ndev);
                goto out;
        }

        /* put the frame in the reordering buffer */
        r->reorder_buf[index] = skb;
        r->stored_mpdu_num++;
        wil_reorder_release(ndev, r);

out:
        spin_unlock(&sta->tid_rx_lock);
}

/* process BAR frame, called in NAPI context */
void wil_rx_bar(struct wil6210_priv *wil, struct wil6210_vif *vif,
                u8 cid, u8 tid, u16 seq)
{
        struct wil_sta_info *sta = &wil->sta[cid];
        struct net_device *ndev = vif_to_ndev(vif);
        struct wil_tid_ampdu_rx *r;

        spin_lock(&sta->tid_rx_lock);

        r = sta->tid_rx[tid];
        if (!r) {
                wil_err(wil, "BAR for non-existing CID %d TID %d\n", cid, tid);
                goto out;
        }
        if (seq_less(seq, r->head_seq_num)) {
                wil_err(wil, "BAR Seq 0x%03x preceding head 0x%03x\n",
                        seq, r->head_seq_num);
                goto out;
        }
        wil_dbg_txrx(wil, "BAR: CID %d MID %d TID %d Seq 0x%03x head 0x%03x\n",
                     cid, vif->mid, tid, seq, r->head_seq_num);
        wil_release_reorder_frames(ndev, r, seq);

out:
        spin_unlock(&sta->tid_rx_lock);
}

struct wil_tid_ampdu_rx *wil_tid_ampdu_rx_alloc(struct wil6210_priv *wil,
                                                int size, u16 ssn)
{
        struct wil_tid_ampdu_rx *r = kzalloc_obj(*r);

        if (!r)
                return NULL;

        r->reorder_buf =
                kzalloc_objs(struct sk_buff *, size);
        if (!r->reorder_buf) {
                kfree(r);
                return NULL;
        }

        r->ssn = ssn;
        r->head_seq_num = ssn;
        r->buf_size = size;
        r->stored_mpdu_num = 0;
        r->first_time = true;
        r->mcast_last_seq = U16_MAX;
        return r;
}

void wil_tid_ampdu_rx_free(struct wil6210_priv *wil,
                           struct wil_tid_ampdu_rx *r)
{
        int i;

        if (!r)
                return;

        /* Do not pass remaining frames to the network stack - it may be
         * not expecting to get any more Rx. Rx from here may lead to
         * kernel OOPS since some per-socket accounting info was already
         * released.
         */
        for (i = 0; i < r->buf_size; i++)
                kfree_skb(r->reorder_buf[i]);

        kfree(r->reorder_buf);
        kfree(r);
}

/* ADDBA processing */
static u16 wil_agg_size(struct wil6210_priv *wil, u16 req_agg_wsize)
{
        u16 max_agg_size = min_t(u16, wil->max_agg_wsize, wil->max_ampdu_size /
                                 (mtu_max + WIL_MAX_MPDU_OVERHEAD));

        if (!req_agg_wsize)
                return max_agg_size;

        return min(max_agg_size, req_agg_wsize);
}

/* Block Ack - Rx side (recipient) */
int wil_addba_rx_request(struct wil6210_priv *wil, u8 mid, u8 cid, u8 tid,
                         u8 dialog_token, __le16 ba_param_set,
                         __le16 ba_timeout, __le16 ba_seq_ctrl)
__acquires(&sta->tid_rx_lock) __releases(&sta->tid_rx_lock)
{
        u16 param_set = le16_to_cpu(ba_param_set);
        u16 agg_timeout = le16_to_cpu(ba_timeout);
        u16 seq_ctrl = le16_to_cpu(ba_seq_ctrl);
        struct wil_sta_info *sta;
        u16 agg_wsize;
        /* bit 0: A-MSDU supported
         * bit 1: policy (should be 0 for us)
         * bits 2..5: TID
         * bits 6..15: buffer size
         */
        u16 req_agg_wsize = WIL_GET_BITS(param_set, 6, 15);
        bool agg_amsdu = wil->use_enhanced_dma_hw &&
                wil->use_rx_hw_reordering &&
                test_bit(WMI_FW_CAPABILITY_AMSDU, wil->fw_capabilities) &&
                wil->amsdu_en && (param_set & BIT(0));
        int ba_policy = param_set & BIT(1);
        u16 ssn = seq_ctrl >> 4;
        struct wil_tid_ampdu_rx *r;
        int rc = 0;

        might_sleep();

        /* sanity checks */
        if (cid >= wil->max_assoc_sta) {
                wil_err(wil, "BACK: invalid CID %d\n", cid);
                rc = -EINVAL;
                goto out;
        }

        sta = &wil->sta[cid];
        if (sta->status != wil_sta_connected) {
                wil_err(wil, "BACK: CID %d not connected\n", cid);
                rc = -EINVAL;
                goto out;
        }

        wil_dbg_wmi(wil,
                    "ADDBA request for CID %d %pM TID %d size %d timeout %d AMSDU%s policy %d token %d SSN 0x%03x\n",
                    cid, sta->addr, tid, req_agg_wsize, agg_timeout,
                    agg_amsdu ? "+" : "-", !!ba_policy, dialog_token, ssn);

        /* apply policies */
        if (req_agg_wsize == 0) {
                wil_dbg_misc(wil, "Suggest BACK wsize %d\n",
                             wil->max_agg_wsize);
                agg_wsize = wil->max_agg_wsize;
        } else {
                agg_wsize = min_t(u16, wil->max_agg_wsize, req_agg_wsize);
        }

        rc = wil->txrx_ops.wmi_addba_rx_resp(wil, mid, cid, tid, dialog_token,
                                             WLAN_STATUS_SUCCESS, agg_amsdu,
                                             agg_wsize, agg_timeout);
        if (rc) {
                wil_err(wil, "do not apply ba, rc(%d)\n", rc);
                goto out;
        }

        /* apply */
        if (!wil->use_rx_hw_reordering) {
                r = wil_tid_ampdu_rx_alloc(wil, agg_wsize, ssn);
                spin_lock_bh(&sta->tid_rx_lock);
                wil_tid_ampdu_rx_free(wil, sta->tid_rx[tid]);
                sta->tid_rx[tid] = r;
                spin_unlock_bh(&sta->tid_rx_lock);
        }

out:
        return rc;
}

/* BACK - Tx side (originator) */
int wil_addba_tx_request(struct wil6210_priv *wil, u8 ringid, u16 wsize)
{
        u8 agg_wsize = wil_agg_size(wil, wsize);
        u16 agg_timeout = 0;
        struct wil_ring_tx_data *txdata = &wil->ring_tx_data[ringid];
        int rc = 0;

        if (txdata->addba_in_progress) {
                wil_dbg_misc(wil, "ADDBA for vring[%d] already in progress\n",
                             ringid);
                goto out;
        }
        if (txdata->agg_wsize) {
                wil_dbg_misc(wil,
                             "ADDBA for vring[%d] already done for wsize %d\n",
                             ringid, txdata->agg_wsize);
                goto out;
        }
        txdata->addba_in_progress = true;
        rc = wmi_addba(wil, txdata->mid, ringid, agg_wsize, agg_timeout);
        if (rc) {
                wil_err(wil, "wmi_addba failed, rc (%d)", rc);
                txdata->addba_in_progress = false;
        }

out:
        return rc;
}