/*
 * Copyright (c) 2012-2017 Qualcomm Atheros, Inc.
 * Copyright (c) 2018, The Linux Foundation. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <linux/etherdevice.h>
#include <net/ieee80211_radiotap.h>
#include <linux/if_arp.h>
#include <linux/moduleparam.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <linux/prefetch.h>

#include "wil6210.h"
#include "wmi.h"
#include "txrx.h"
#include "trace.h"

static bool rtap_include_phy_info;
module_param(rtap_include_phy_info, bool, 0444);
MODULE_PARM_DESC(rtap_include_phy_info,
                 " Include PHY info in the radiotap header, default - no");

bool rx_align_2;
module_param(rx_align_2, bool, 0444);
MODULE_PARM_DESC(rx_align_2, " align Rx buffers on 4*n+2, default - no");

bool rx_large_buf;
module_param(rx_large_buf, bool, 0444);
MODULE_PARM_DESC(rx_large_buf, " allocate 8KB RX buffers, default - no");

static inline uint wil_rx_snaplen(void)
{
        return rx_align_2 ? 6 : 0;
}

static inline int wil_vring_is_empty(struct vring *vring)
{
        return vring->swhead == vring->swtail;
}

static inline u32 wil_vring_next_tail(struct vring *vring)
{
        return (vring->swtail + 1) % vring->size;
}

static inline void wil_vring_advance_head(struct vring *vring, int n)
{
        vring->swhead = (vring->swhead + n) % vring->size;
}

static inline int wil_vring_is_full(struct vring *vring)
{
        return wil_vring_next_tail(vring) == vring->swhead;
}

/* Used space in Tx Vring */
static inline int wil_vring_used_tx(struct vring *vring)
{
        u32 swhead = vring->swhead;
        u32 swtail = vring->swtail;
        return (vring->size + swhead - swtail) % vring->size;
}

/* Available space in Tx Vring */
static inline int wil_vring_avail_tx(struct vring *vring)
{
        return vring->size - wil_vring_used_tx(vring) - 1;
}

/* wil_vring_wmark_low - low watermark for available descriptor space */
static inline int wil_vring_wmark_low(struct vring *vring)
{
        return vring->size/8;
}

/* wil_vring_wmark_high - high watermark for available descriptor space */
static inline int wil_vring_wmark_high(struct vring *vring)
{
        return vring->size/4;
}

/* returns true if num avail descriptors is lower than wmark_low */
static inline int wil_vring_avail_low(struct vring *vring)
{
        return wil_vring_avail_tx(vring) < wil_vring_wmark_low(vring);
}

/* returns true if num avail descriptors is higher than wmark_high */
static inline int wil_vring_avail_high(struct vring *vring)
{
        return wil_vring_avail_tx(vring) > wil_vring_wmark_high(vring);
}

/* returns true when all tx vrings are empty */
bool wil_is_tx_idle(struct wil6210_priv *wil)
{
        int i;
        unsigned long data_comp_to;

        for (i = 0; i < WIL6210_MAX_TX_RINGS; i++) {
                struct vring *vring = &wil->vring_tx[i];
                int vring_index = vring - wil->vring_tx;
                struct vring_tx_data *txdata = &wil->vring_tx_data[vring_index];

                spin_lock(&txdata->lock);

                if (!vring->va || !txdata->enabled) {
                        spin_unlock(&txdata->lock);
                        continue;
                }

                data_comp_to = jiffies + msecs_to_jiffies(
                                        WIL_DATA_COMPLETION_TO_MS);
                if (test_bit(wil_status_napi_en, wil->status)) {
                        while (!wil_vring_is_empty(vring)) {
                                if (time_after(jiffies, data_comp_to)) {
                                        wil_dbg_pm(wil,
                                                   "TO waiting for idle tx\n");
                                        spin_unlock(&txdata->lock);
                                        return false;
                                }
                                wil_dbg_ratelimited(wil,
                                                    "tx vring is not empty -> NAPI\n");
                                spin_unlock(&txdata->lock);
                                napi_synchronize(&wil->napi_tx);
                                msleep(20);
                                spin_lock(&txdata->lock);
                                if (!vring->va || !txdata->enabled)
                                        break;
                        }
                }

                spin_unlock(&txdata->lock);
        }

        return true;
}

/* wil_val_in_range - check if value in [min,max) */
static inline bool wil_val_in_range(int val, int min, int max)
{
        return val >= min && val < max;
}

static int wil_vring_alloc(struct wil6210_priv *wil, struct vring *vring)
{
        struct device *dev = wil_to_dev(wil);
        size_t sz = vring->size * sizeof(vring->va[0]);
        uint i;

        wil_dbg_misc(wil, "vring_alloc:\n");

        BUILD_BUG_ON(sizeof(vring->va[0]) != 32);

        vring->swhead = 0;
        vring->swtail = 0;
        vring->ctx = kcalloc(vring->size, sizeof(vring->ctx[0]), GFP_KERNEL);
        if (!vring->ctx) {
                vring->va = NULL;
                return -ENOMEM;
        }

        /* vring->va should be aligned on its size rounded up to power of 2
         * This is granted by the dma_alloc_coherent.
         *
         * HW has limitation that all vrings addresses must share the same
         * upper 16 msb bits part of 48 bits address. To workaround that,
         * if we are using more than 32 bit addresses switch to 32 bit
         * allocation before allocating vring memory.
         *
         * There's no check for the return value of dma_set_mask_and_coherent,
         * since we assume if we were able to set the mask during
         * initialization in this system it will not fail if we set it again
         */
        if (wil->dma_addr_size > 32)
                dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));

        vring->va = dma_alloc_coherent(dev, sz, &vring->pa, GFP_KERNEL);
        if (!vring->va) {
                kfree(vring->ctx);
                vring->ctx = NULL;
                return -ENOMEM;
        }

        if (wil->dma_addr_size > 32)
                dma_set_mask_and_coherent(dev,
                                          DMA_BIT_MASK(wil->dma_addr_size));

        /* initially, all descriptors are SW owned
         * For Tx and Rx, ownership bit is at the same location, thus
         * we can use any
         */
        for (i = 0; i < vring->size; i++) {
                volatile struct vring_tx_desc *_d = &vring->va[i].tx;

                _d->dma.status = TX_DMA_STATUS_DU;
        }

        wil_dbg_misc(wil, "vring[%d] 0x%p:%pad 0x%p\n", vring->size,
                     vring->va, &vring->pa, vring->ctx);

        return 0;
}

static void wil_txdesc_unmap(struct device *dev, struct vring_tx_desc *d,
                             struct wil_ctx *ctx)
{
        dma_addr_t pa = wil_desc_addr(&d->dma.addr);
        u16 dmalen = le16_to_cpu(d->dma.length);

        switch (ctx->mapped_as) {
        case wil_mapped_as_single:
                dma_unmap_single(dev, pa, dmalen, DMA_TO_DEVICE);
                break;
        case wil_mapped_as_page:
                dma_unmap_page(dev, pa, dmalen, DMA_TO_DEVICE);
                break;
        default:
                break;
        }
}

static void wil_vring_free(struct wil6210_priv *wil, struct vring *vring,
                           int tx)
{
        struct device *dev = wil_to_dev(wil);
        size_t sz = vring->size * sizeof(vring->va[0]);

        lockdep_assert_held(&wil->mutex);
        if (tx) {
                int vring_index = vring - wil->vring_tx;

                wil_dbg_misc(wil, "free Tx vring %d [%d] 0x%p:%pad 0x%p\n",
                             vring_index, vring->size, vring->va,
                             &vring->pa, vring->ctx);
        } else {
                wil_dbg_misc(wil, "free Rx vring [%d] 0x%p:%pad 0x%p\n",
                             vring->size, vring->va,
                             &vring->pa, vring->ctx);
        }

        while (!wil_vring_is_empty(vring)) {
                dma_addr_t pa;
                u16 dmalen;
                struct wil_ctx *ctx;

                if (tx) {
                        struct vring_tx_desc dd, *d = &dd;
                        volatile struct vring_tx_desc *_d =
                                        &vring->va[vring->swtail].tx;

                        ctx = &vring->ctx[vring->swtail];
                        if (!ctx) {
                                wil_dbg_txrx(wil,
                                             "ctx(%d) was already completed\n",
                                             vring->swtail);
                                vring->swtail = wil_vring_next_tail(vring);
                                continue;
                        }
                        *d = *_d;
                        wil_txdesc_unmap(dev, d, ctx);
                        if (ctx->skb)
                                dev_kfree_skb_any(ctx->skb);
                        vring->swtail = wil_vring_next_tail(vring);
                } else { /* rx */
                        struct vring_rx_desc dd, *d = &dd;
                        volatile struct vring_rx_desc *_d =
                                        &vring->va[vring->swhead].rx;

                        ctx = &vring->ctx[vring->swhead];
                        *d = *_d;
                        pa = wil_desc_addr(&d->dma.addr);
                        dmalen = le16_to_cpu(d->dma.length);
                        dma_unmap_single(dev, pa, dmalen, DMA_FROM_DEVICE);
                        kfree_skb(ctx->skb);
                        wil_vring_advance_head(vring, 1);
                }
        }
        dma_free_coherent(dev, sz, (void *)vring->va, vring->pa);
        kfree(vring->ctx);
        vring->pa = 0;
        vring->va = NULL;
        vring->ctx = NULL;
}

/**
 * Allocate one skb for Rx VRING
 *
 * Safe to call from IRQ
 */
static int wil_vring_alloc_skb(struct wil6210_priv *wil, struct vring *vring,
                               u32 i, int headroom)
{
        struct device *dev = wil_to_dev(wil);
        unsigned int sz = wil->rx_buf_len + ETH_HLEN + wil_rx_snaplen();
        struct vring_rx_desc dd, *d = &dd;
        volatile struct vring_rx_desc *_d = &vring->va[i].rx;
        dma_addr_t pa;
        struct sk_buff *skb = dev_alloc_skb(sz + headroom);

        if (unlikely(!skb))
                return -ENOMEM;

        skb_reserve(skb, headroom);
        skb_put(skb, sz);

        pa = dma_map_single(dev, skb->data, skb->len, DMA_FROM_DEVICE);
        if (unlikely(dma_mapping_error(dev, pa))) {
                kfree_skb(skb);
                return -ENOMEM;
        }

        d->dma.d0 = RX_DMA_D0_CMD_DMA_RT | RX_DMA_D0_CMD_DMA_IT;
        wil_desc_addr_set(&d->dma.addr, pa);
        /* ip_length don't care */
        /* b11 don't care */
        /* error don't care */
        d->dma.status = 0; /* BIT(0) should be 0 for HW_OWNED */
        d->dma.length = cpu_to_le16(sz);
        *_d = *d;
        vring->ctx[i].skb = skb;

        return 0;
}

/**
 * Adds radiotap header
 *
 * Any error indicated as "Bad FCS"
 *
 * Vendor data for 04:ce:14-1 (Wilocity-1) consists of:
 *  - Rx descriptor: 32 bytes
 *  - Phy info
 */
static void wil_rx_add_radiotap_header(struct wil6210_priv *wil,
                                       struct sk_buff *skb)
{
        struct wil6210_rtap {
                struct ieee80211_radiotap_header rthdr;
                /* fields should be in the order of bits in rthdr.it_present */
                /* flags */
                u8 flags;
                /* channel */
                __le16 chnl_freq __aligned(2);
                __le16 chnl_flags;
                /* MCS */
                u8 mcs_present;
                u8 mcs_flags;
                u8 mcs_index;
        } __packed;
        struct wil6210_rtap_vendor {
                struct wil6210_rtap rtap;
                /* vendor */
                u8 vendor_oui[3] __aligned(2);
                u8 vendor_ns;
                __le16 vendor_skip;
                u8 vendor_data[0];
        } __packed;
        struct vring_rx_desc *d = wil_skb_rxdesc(skb);
        struct wil6210_rtap_vendor *rtap_vendor;
        int rtap_len = sizeof(struct wil6210_rtap);
        int phy_length = 0; /* phy info header size, bytes */
        static char phy_data[128];
        struct ieee80211_channel *ch = wil->monitor_chandef.chan;

        if (rtap_include_phy_info) {
                rtap_len = sizeof(*rtap_vendor) + sizeof(*d);
                /* calculate additional length */
                if (d->dma.status & RX_DMA_STATUS_PHY_INFO) {
                        /**
                         * PHY info starts from 8-byte boundary
                         * there are 8-byte lines, last line may be partially
                         * written (HW bug), thus FW configures for last line
                         * to be excessive. Driver skips this last line.
                         */
                        int len = min_t(int, 8 + sizeof(phy_data),
                                        wil_rxdesc_phy_length(d));

                        if (len > 8) {
                                void *p = skb_tail_pointer(skb);
                                void *pa = PTR_ALIGN(p, 8);

                                if (skb_tailroom(skb) >= len + (pa - p)) {
                                        phy_length = len - 8;
                                        memcpy(phy_data, pa, phy_length);
                                }
                        }
                }
                rtap_len += phy_length;
        }

        if (skb_headroom(skb) < rtap_len &&
            pskb_expand_head(skb, rtap_len, 0, GFP_ATOMIC)) {
                wil_err(wil, "Unable to expand headroom to %d\n", rtap_len);
                return;
        }

        rtap_vendor = skb_push(skb, rtap_len);
        memset(rtap_vendor, 0, rtap_len);

        rtap_vendor->rtap.rthdr.it_version = PKTHDR_RADIOTAP_VERSION;
        rtap_vendor->rtap.rthdr.it_len = cpu_to_le16(rtap_len);
        rtap_vendor->rtap.rthdr.it_present = cpu_to_le32(
                        (1 << IEEE80211_RADIOTAP_FLAGS) |
                        (1 << IEEE80211_RADIOTAP_CHANNEL) |
                        (1 << IEEE80211_RADIOTAP_MCS));
        if (d->dma.status & RX_DMA_STATUS_ERROR)
                rtap_vendor->rtap.flags |= IEEE80211_RADIOTAP_F_BADFCS;

        rtap_vendor->rtap.chnl_freq = cpu_to_le16(ch ? ch->center_freq : 58320);
        rtap_vendor->rtap.chnl_flags = cpu_to_le16(0);

        rtap_vendor->rtap.mcs_present = IEEE80211_RADIOTAP_MCS_HAVE_MCS;
        rtap_vendor->rtap.mcs_flags = 0;
        rtap_vendor->rtap.mcs_index = wil_rxdesc_mcs(d);

        if (rtap_include_phy_info) {
                rtap_vendor->rtap.rthdr.it_present |= cpu_to_le32(1 <<
                                IEEE80211_RADIOTAP_VENDOR_NAMESPACE);
                /* OUI for Wilocity 04:ce:14 */
                rtap_vendor->vendor_oui[0] = 0x04;
                rtap_vendor->vendor_oui[1] = 0xce;
                rtap_vendor->vendor_oui[2] = 0x14;
                rtap_vendor->vendor_ns = 1;
                /* Rx descriptor + PHY data  */
                rtap_vendor->vendor_skip = cpu_to_le16(sizeof(*d) +
                                                       phy_length);
                memcpy(rtap_vendor->vendor_data, (void *)d, sizeof(*d));
                memcpy(rtap_vendor->vendor_data + sizeof(*d), phy_data,
                       phy_length);
        }
}

/* similar to ieee80211_ version, but FC contain only 1-st byte */
static inline int wil_is_back_req(u8 fc)
{
        return (fc & (IEEE80211_FCTL_FTYPE | IEEE80211_FCTL_STYPE)) ==
               (IEEE80211_FTYPE_CTL | IEEE80211_STYPE_BACK_REQ);
}

bool wil_is_rx_idle(struct wil6210_priv *wil)
{
        struct vring_rx_desc *_d;
        struct vring *vring = &wil->vring_rx;

        _d = (struct vring_rx_desc *)&vring->va[vring->swhead].rx;
        if (_d->dma.status & RX_DMA_STATUS_DU)
                return false;

        return true;
}

/**
 * reap 1 frame from @swhead
 *
 * Rx descriptor copied to skb->cb
 *
 * Safe to call from IRQ
 */
static struct sk_buff *wil_vring_reap_rx(struct wil6210_priv *wil,
                                         struct vring *vring)
{
        struct device *dev = wil_to_dev(wil);
        struct wil6210_vif *vif;
        struct net_device *ndev;
        volatile struct vring_rx_desc *_d;
        struct vring_rx_desc *d;
        struct sk_buff *skb;
        dma_addr_t pa;
        unsigned int snaplen = wil_rx_snaplen();
        unsigned int sz = wil->rx_buf_len + ETH_HLEN + snaplen;
        u16 dmalen;
        u8 ftype;
        int cid, mid;
        int i;
        struct wil_net_stats *stats;

        BUILD_BUG_ON(sizeof(struct vring_rx_desc) > sizeof(skb->cb));

again:
        if (unlikely(wil_vring_is_empty(vring)))
                return NULL;

        i = (int)vring->swhead;
        _d = &vring->va[i].rx;
        if (unlikely(!(_d->dma.status & RX_DMA_STATUS_DU))) {
                /* it is not error, we just reached end of Rx done area */
                return NULL;
        }

        skb = vring->ctx[i].skb;
        vring->ctx[i].skb = NULL;
        wil_vring_advance_head(vring, 1);
        if (!skb) {
                wil_err(wil, "No Rx skb at [%d]\n", i);
                goto again;
        }
        d = wil_skb_rxdesc(skb);
        *d = *_d;
        pa = wil_desc_addr(&d->dma.addr);

        dma_unmap_single(dev, pa, sz, DMA_FROM_DEVICE);
        dmalen = le16_to_cpu(d->dma.length);

        trace_wil6210_rx(i, d);
        wil_dbg_txrx(wil, "Rx[%3d] : %d bytes\n", i, dmalen);
        wil_hex_dump_txrx("RxD ", DUMP_PREFIX_NONE, 32, 4,
                          (const void *)d, sizeof(*d), false);

        cid = wil_rxdesc_cid(d);
        mid = wil_rxdesc_mid(d);
        vif = wil->vifs[mid];

        if (unlikely(!vif)) {
                wil_dbg_txrx(wil, "skipped RX descriptor with invalid mid %d",
                             mid);
                kfree_skb(skb);
                goto again;
        }
        ndev = vif_to_ndev(vif);
        stats = &wil->sta[cid].stats;

        if (unlikely(dmalen > sz)) {
                wil_err(wil, "Rx size too large: %d bytes!\n", dmalen);
                stats->rx_large_frame++;
                kfree_skb(skb);
                goto again;
        }
        skb_trim(skb, dmalen);

        prefetch(skb->data);

        wil_hex_dump_txrx("Rx ", DUMP_PREFIX_OFFSET, 16, 1,
                          skb->data, skb_headlen(skb), false);

        stats->last_mcs_rx = wil_rxdesc_mcs(d);
        if (stats->last_mcs_rx < ARRAY_SIZE(stats->rx_per_mcs))
                stats->rx_per_mcs[stats->last_mcs_rx]++;

        /* use radiotap header only if required */
        if (ndev->type == ARPHRD_IEEE80211_RADIOTAP)
                wil_rx_add_radiotap_header(wil, skb);

        /* no extra checks if in sniffer mode */
        if (ndev->type != ARPHRD_ETHER)
                return skb;
        /* Non-data frames may be delivered through Rx DMA channel (ex: BAR)
         * Driver should recognize it by frame type, that is found
         * in Rx descriptor. If type is not data, it is 802.11 frame as is
         */
        ftype = wil_rxdesc_ftype(d) << 2;
        if (unlikely(ftype != IEEE80211_FTYPE_DATA)) {
                u8 fc1 = wil_rxdesc_fc1(d);
                int tid = wil_rxdesc_tid(d);
                u16 seq = wil_rxdesc_seq(d);

                wil_dbg_txrx(wil,
                             "Non-data frame FC[7:0] 0x%02x MID %d CID %d TID %d Seq 0x%03x\n",
                             fc1, mid, cid, tid, seq);
                stats->rx_non_data_frame++;
                if (wil_is_back_req(fc1)) {
                        wil_dbg_txrx(wil,
                                     "BAR: MID %d CID %d TID %d Seq 0x%03x\n",
                                     mid, cid, tid, seq);
                        wil_rx_bar(wil, vif, cid, tid, seq);
                } else {
                        /* print again all info. One can enable only this
                         * without overhead for printing every Rx frame
                         */
                        wil_dbg_txrx(wil,
                                     "Unhandled non-data frame FC[7:0] 0x%02x MID %d CID %d TID %d Seq 0x%03x\n",
                                     fc1, mid, cid, tid, seq);
                        wil_hex_dump_txrx("RxD ", DUMP_PREFIX_NONE, 32, 4,
                                          (const void *)d, sizeof(*d), false);
                        wil_hex_dump_txrx("Rx ", DUMP_PREFIX_OFFSET, 16, 1,
                                          skb->data, skb_headlen(skb), false);
                }
                kfree_skb(skb);
                goto again;
        }

        if (unlikely(skb->len < ETH_HLEN + snaplen)) {
                wil_err(wil, "Short frame, len = %d\n", skb->len);
                stats->rx_short_frame++;
                kfree_skb(skb);
                goto again;
        }

        /* L4 IDENT is on when HW calculated checksum, check status
         * and in case of error drop the packet
         * higher stack layers will handle retransmission (if required)
         */
        if (likely(d->dma.status & RX_DMA_STATUS_L4I)) {
                /* L4 protocol identified, csum calculated */
                if (likely((d->dma.error & RX_DMA_ERROR_L4_ERR) == 0))
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                /* If HW reports bad checksum, let IP stack re-check it
                 * For example, HW don't understand Microsoft IP stack that
                 * mis-calculates TCP checksum - if it should be 0x0,
                 * it writes 0xffff in violation of RFC 1624
                 */
        }

        if (snaplen) {
                /* Packet layout
                 * +-------+-------+---------+------------+------+
                 * | SA(6) | DA(6) | SNAP(6) | ETHTYPE(2) | DATA |
                 * +-------+-------+---------+------------+------+
                 * Need to remove SNAP, shifting SA and DA forward
                 */
                memmove(skb->data + snaplen, skb->data, 2 * ETH_ALEN);
                skb_pull(skb, snaplen);
        }

        return skb;
}

/**
 * allocate and fill up to @count buffers in rx ring
 * buffers posted at @swtail
 * Note: we have a single RX queue for servicing all VIFs, but we
 * allocate skbs with headroom according to main interface only. This
 * means it will not work with monitor interface together with other VIFs.
 * Currently we only support monitor interface on its own without other VIFs,
 * and we will need to fix this code once we add support.
 */
static int wil_rx_refill(struct wil6210_priv *wil, int count)
{
        struct net_device *ndev = wil->main_ndev;
        struct vring *v = &wil->vring_rx;
        u32 next_tail;
        int rc = 0;
        int headroom = ndev->type == ARPHRD_IEEE80211_RADIOTAP ?
                        WIL6210_RTAP_SIZE : 0;

        for (; next_tail = wil_vring_next_tail(v),
                        (next_tail != v->swhead) && (count-- > 0);
                        v->swtail = next_tail) {
                rc = wil_vring_alloc_skb(wil, v, v->swtail, headroom);
                if (unlikely(rc)) {
                        wil_err_ratelimited(wil, "Error %d in rx refill[%d]\n",
                                            rc, v->swtail);
                        break;
                }
        }

        /* make sure all writes to descriptors (shared memory) are done before
         * committing them to HW
         */
        wmb();

        wil_w(wil, v->hwtail, v->swtail);

        return rc;
}

/**
 * reverse_memcmp - Compare two areas of memory, in reverse order
 * @cs: One area of memory
 * @ct: Another area of memory
 * @count: The size of the area.
 *
 * Cut'n'paste from original memcmp (see lib/string.c)
 * with minimal modifications
 */
static int reverse_memcmp(const void *cs, const void *ct, size_t count)
{
        const unsigned char *su1, *su2;
        int res = 0;

        for (su1 = cs + count - 1, su2 = ct + count - 1; count > 0;
             --su1, --su2, count--) {
                res = *su1 - *su2;
                if (res)
                        break;
        }
        return res;
}

static int wil_rx_crypto_check(struct wil6210_priv *wil, struct sk_buff *skb)
{
        struct vring_rx_desc *d = wil_skb_rxdesc(skb);
        int cid = wil_rxdesc_cid(d);
        int tid = wil_rxdesc_tid(d);
        int key_id = wil_rxdesc_key_id(d);
        int mc = wil_rxdesc_mcast(d);
        struct wil_sta_info *s = &wil->sta[cid];
        struct wil_tid_crypto_rx *c = mc ? &s->group_crypto_rx :
                                      &s->tid_crypto_rx[tid];
        struct wil_tid_crypto_rx_single *cc = &c->key_id[key_id];
        const u8 *pn = (u8 *)&d->mac.pn_15_0;

        if (!cc->key_set) {
                wil_err_ratelimited(wil,
                                    "Key missing. CID %d TID %d MCast %d KEY_ID %d\n",
                                    cid, tid, mc, key_id);
                return -EINVAL;
        }

        if (reverse_memcmp(pn, cc->pn, IEEE80211_GCMP_PN_LEN) <= 0) {
                wil_err_ratelimited(wil,
                                    "Replay attack. CID %d TID %d MCast %d KEY_ID %d PN %6phN last %6phN\n",
                                    cid, tid, mc, key_id, pn, cc->pn);
                return -EINVAL;
        }
        memcpy(cc->pn, pn, IEEE80211_GCMP_PN_LEN);

        return 0;
}

/*
 * Pass Rx packet to the netif. Update statistics.
 * Called in softirq context (NAPI poll).
 */
void wil_netif_rx_any(struct sk_buff *skb, struct net_device *ndev)
{
        gro_result_t rc = GRO_NORMAL;
        struct wil6210_vif *vif = ndev_to_vif(ndev);
        struct wil6210_priv *wil = ndev_to_wil(ndev);
        struct wireless_dev *wdev = vif_to_wdev(vif);
        unsigned int len = skb->len;
        struct vring_rx_desc *d = wil_skb_rxdesc(skb);
        int cid = wil_rxdesc_cid(d); /* always 0..7, no need to check */
        int security = wil_rxdesc_security(d);
        struct ethhdr *eth = (void *)skb->data;
        /* here looking for DA, not A1, thus Rxdesc's 'mcast' indication
         * is not suitable, need to look at data
         */
        int mcast = is_multicast_ether_addr(eth->h_dest);
        struct wil_net_stats *stats = &wil->sta[cid].stats;
        struct sk_buff *xmit_skb = NULL;
        static const char * const gro_res_str[] = {
                [GRO_MERGED]            = "GRO_MERGED",
                [GRO_MERGED_FREE]       = "GRO_MERGED_FREE",
                [GRO_HELD]              = "GRO_HELD",
                [GRO_NORMAL]            = "GRO_NORMAL",
                [GRO_DROP]              = "GRO_DROP",
        };

        if (ndev->features & NETIF_F_RXHASH)
                /* fake L4 to ensure it won't be re-calculated later
                 * set hash to any non-zero value to activate rps
                 * mechanism, core will be chosen according
                 * to user-level rps configuration.
                 */
                skb_set_hash(skb, 1, PKT_HASH_TYPE_L4);

        skb_orphan(skb);

        if (security && (wil_rx_crypto_check(wil, skb) != 0)) {
                rc = GRO_DROP;
                dev_kfree_skb(skb);
                stats->rx_replay++;
                goto stats;
        }

        if (wdev->iftype == NL80211_IFTYPE_AP && !vif->ap_isolate) {
                if (mcast) {
                        /* send multicast frames both to higher layers in
                         * local net stack and back to the wireless medium
                         */
                        xmit_skb = skb_copy(skb, GFP_ATOMIC);
                } else {
                        int xmit_cid = wil_find_cid(wil, vif->mid,
                                                    eth->h_dest);

                        if (xmit_cid >= 0) {
                                /* The destination station is associated to
                                 * this AP (in this VLAN), so send the frame
                                 * directly to it and do not pass it to local
                                 * net stack.
                                 */
                                xmit_skb = skb;
                                skb = NULL;
                        }
                }
        }
        if (xmit_skb) {
                /* Send to wireless media and increase priority by 256 to
                 * keep the received priority instead of reclassifying
                 * the frame (see cfg80211_classify8021d).
                 */
                xmit_skb->dev = ndev;
                xmit_skb->priority += 256;
                xmit_skb->protocol = htons(ETH_P_802_3);
                skb_reset_network_header(xmit_skb);
                skb_reset_mac_header(xmit_skb);
                wil_dbg_txrx(wil, "Rx -> Tx %d bytes\n", len);
                dev_queue_xmit(xmit_skb);
        }

        if (skb) { /* deliver to local stack */
                skb->protocol = eth_type_trans(skb, ndev);
                skb->dev = ndev;
                rc = napi_gro_receive(&wil->napi_rx, skb);
                wil_dbg_txrx(wil, "Rx complete %d bytes => %s\n",
                             len, gro_res_str[rc]);
        }
stats:
        /* statistics. rc set to GRO_NORMAL for AP bridging */
        if (unlikely(rc == GRO_DROP)) {
                ndev->stats.rx_dropped++;
                stats->rx_dropped++;
                wil_dbg_txrx(wil, "Rx drop %d bytes\n", len);
        } else {
                ndev->stats.rx_packets++;
                stats->rx_packets++;
                ndev->stats.rx_bytes += len;
                stats->rx_bytes += len;
                if (mcast)
                        ndev->stats.multicast++;
        }
}

/**
 * Proceed all completed skb's from Rx VRING
 *
 * Safe to call from NAPI poll, i.e. softirq with interrupts enabled
 */
void wil_rx_handle(struct wil6210_priv *wil, int *quota)
{
        struct net_device *ndev = wil->main_ndev;
        struct wireless_dev *wdev = ndev->ieee80211_ptr;
        struct vring *v = &wil->vring_rx;
        struct sk_buff *skb;

        if (unlikely(!v->va)) {
                wil_err(wil, "Rx IRQ while Rx not yet initialized\n");
                return;
        }
        wil_dbg_txrx(wil, "rx_handle\n");
        while ((*quota > 0) && (NULL != (skb = wil_vring_reap_rx(wil, v)))) {
                (*quota)--;

                /* monitor is currently supported on main interface only */
                if (wdev->iftype == NL80211_IFTYPE_MONITOR) {
                        skb->dev = ndev;
                        skb_reset_mac_header(skb);
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                        skb->pkt_type = PACKET_OTHERHOST;
                        skb->protocol = htons(ETH_P_802_2);
                        wil_netif_rx_any(skb, ndev);
                } else {
                        wil_rx_reorder(wil, skb);
                }
        }
        wil_rx_refill(wil, v->size);
}

static void wil_rx_buf_len_init(struct wil6210_priv *wil)
{
        wil->rx_buf_len = rx_large_buf ?
                WIL_MAX_ETH_MTU : TXRX_BUF_LEN_DEFAULT - WIL_MAX_MPDU_OVERHEAD;
        if (mtu_max > wil->rx_buf_len) {
                /* do not allow RX buffers to be smaller than mtu_max, for
                 * backward compatibility (mtu_max parameter was also used
                 * to support receiving large packets)
                 */
                wil_info(wil, "Override RX buffer to mtu_max(%d)\n", mtu_max);
                wil->rx_buf_len = mtu_max;
        }
}

int wil_rx_init(struct wil6210_priv *wil, u16 size)
{
        struct vring *vring = &wil->vring_rx;
        int rc;

        wil_dbg_misc(wil, "rx_init\n");

        if (vring->va) {
                wil_err(wil, "Rx ring already allocated\n");
                return -EINVAL;
        }

        wil_rx_buf_len_init(wil);

        vring->size = size;
        rc = wil_vring_alloc(wil, vring);
        if (rc)
                return rc;

        rc = wmi_rx_chain_add(wil, vring);
        if (rc)
                goto err_free;

        rc = wil_rx_refill(wil, vring->size);
        if (rc)
                goto err_free;

        return 0;
 err_free:
        wil_vring_free(wil, vring, 0);

        return rc;
}

void wil_rx_fini(struct wil6210_priv *wil)
{
        struct vring *vring = &wil->vring_rx;

        wil_dbg_misc(wil, "rx_fini\n");

        if (vring->va)
                wil_vring_free(wil, vring, 0);
}

static inline void wil_tx_data_init(struct vring_tx_data *txdata)
{
        spin_lock_bh(&txdata->lock);
        txdata->dot1x_open = 0;
        txdata->enabled = 0;
        txdata->idle = 0;
        txdata->last_idle = 0;
        txdata->begin = 0;
        txdata->agg_wsize = 0;
        txdata->agg_timeout = 0;
        txdata->agg_amsdu = 0;
        txdata->addba_in_progress = false;
        txdata->mid = U8_MAX;
        spin_unlock_bh(&txdata->lock);
}

int wil_vring_init_tx(struct wil6210_vif *vif, int id, int size,
                      int cid, int tid)
{
        struct wil6210_priv *wil = vif_to_wil(vif);
        int rc;
        struct wmi_vring_cfg_cmd cmd = {
                .action = cpu_to_le32(WMI_VRING_CMD_ADD),
                .vring_cfg = {
                        .tx_sw_ring = {
                                .max_mpdu_size =
                                        cpu_to_le16(wil_mtu2macbuf(mtu_max)),
                                .ring_size = cpu_to_le16(size),
                        },
                        .ringid = id,
                        .cidxtid = mk_cidxtid(cid, tid),
                        .encap_trans_type = WMI_VRING_ENC_TYPE_802_3,
                        .mac_ctrl = 0,
                        .to_resolution = 0,
                        .agg_max_wsize = 0,
                        .schd_params = {
                                .priority = cpu_to_le16(0),
                                .timeslot_us = cpu_to_le16(0xfff),
                        },
                },
        };
        struct {
                struct wmi_cmd_hdr wmi;
                struct wmi_vring_cfg_done_event cmd;
        } __packed reply = {
                .cmd = {.status = WMI_FW_STATUS_FAILURE},
        };
        struct vring *vring = &wil->vring_tx[id];
        struct vring_tx_data *txdata = &wil->vring_tx_data[id];

        wil_dbg_misc(wil, "vring_init_tx: max_mpdu_size %d\n",
                     cmd.vring_cfg.tx_sw_ring.max_mpdu_size);
        lockdep_assert_held(&wil->mutex);

        if (vring->va) {
                wil_err(wil, "Tx ring [%d] already allocated\n", id);
                rc = -EINVAL;
                goto out;
        }

        wil_tx_data_init(txdata);
        vring->size = size;
        rc = wil_vring_alloc(wil, vring);
        if (rc)
                goto out;

        wil->vring2cid_tid[id][0] = cid;
        wil->vring2cid_tid[id][1] = tid;

        cmd.vring_cfg.tx_sw_ring.ring_mem_base = cpu_to_le64(vring->pa);

        if (!vif->privacy)
                txdata->dot1x_open = true;
        rc = wmi_call(wil, WMI_VRING_CFG_CMDID, vif->mid, &cmd, sizeof(cmd),
                      WMI_VRING_CFG_DONE_EVENTID, &reply, sizeof(reply), 100);
        if (rc)
                goto out_free;

        if (reply.cmd.status != WMI_FW_STATUS_SUCCESS) {

                wil_err(wil, "Tx config failed, status 0x%02x\n",
                        reply.cmd.status);
                rc = -EINVAL;
                goto out_free;
        }

        spin_lock_bh(&txdata->lock);
        vring->hwtail = le32_to_cpu(reply.cmd.tx_vring_tail_ptr);
        txdata->mid = vif->mid;
        txdata->enabled = 1;
        spin_unlock_bh(&txdata->lock);

        if (txdata->dot1x_open && (agg_wsize >= 0))
                wil_addba_tx_request(wil, id, agg_wsize);

        return 0;
 out_free:
        spin_lock_bh(&txdata->lock);
        txdata->dot1x_open = false;
        txdata->enabled = 0;
        spin_unlock_bh(&txdata->lock);
        wil_vring_free(wil, vring, 1);
        wil->vring2cid_tid[id][0] = WIL6210_MAX_CID;
        wil->vring2cid_tid[id][1] = 0;

 out:

        return rc;
}

int wil_vring_init_bcast(struct wil6210_vif *vif, int id, int size)
{
        struct wil6210_priv *wil = vif_to_wil(vif);
        int rc;
        struct wmi_bcast_vring_cfg_cmd cmd = {
                .action = cpu_to_le32(WMI_VRING_CMD_ADD),
                .vring_cfg = {
                        .tx_sw_ring = {
                                .max_mpdu_size =
                                        cpu_to_le16(wil_mtu2macbuf(mtu_max)),
                                .ring_size = cpu_to_le16(size),
                        },
                        .ringid = id,
                        .encap_trans_type = WMI_VRING_ENC_TYPE_802_3,
                },
        };
        struct {
                struct wmi_cmd_hdr wmi;
                struct wmi_vring_cfg_done_event cmd;
        } __packed reply = {
                .cmd = {.status = WMI_FW_STATUS_FAILURE},
        };
        struct vring *vring = &wil->vring_tx[id];
        struct vring_tx_data *txdata = &wil->vring_tx_data[id];

        wil_dbg_misc(wil, "vring_init_bcast: max_mpdu_size %d\n",
                     cmd.vring_cfg.tx_sw_ring.max_mpdu_size);
        lockdep_assert_held(&wil->mutex);

        if (vring->va) {
                wil_err(wil, "Tx ring [%d] already allocated\n", id);
                rc = -EINVAL;
                goto out;
        }

        wil_tx_data_init(txdata);
        vring->size = size;
        rc = wil_vring_alloc(wil, vring);
        if (rc)
                goto out;

        wil->vring2cid_tid[id][0] = WIL6210_MAX_CID; /* CID */
        wil->vring2cid_tid[id][1] = 0; /* TID */

        cmd.vring_cfg.tx_sw_ring.ring_mem_base = cpu_to_le64(vring->pa);

        if (!vif->privacy)
                txdata->dot1x_open = true;
        rc = wmi_call(wil, WMI_BCAST_VRING_CFG_CMDID, vif->mid,
                      &cmd, sizeof(cmd),
                      WMI_VRING_CFG_DONE_EVENTID, &reply, sizeof(reply), 100);
        if (rc)
                goto out_free;

        if (reply.cmd.status != WMI_FW_STATUS_SUCCESS) {
                wil_err(wil, "Tx config failed, status 0x%02x\n",
                        reply.cmd.status);
                rc = -EINVAL;
                goto out_free;
        }

        spin_lock_bh(&txdata->lock);
        vring->hwtail = le32_to_cpu(reply.cmd.tx_vring_tail_ptr);
        txdata->mid = vif->mid;
        txdata->enabled = 1;
        spin_unlock_bh(&txdata->lock);

        return 0;
 out_free:
        spin_lock_bh(&txdata->lock);
        txdata->enabled = 0;
        txdata->dot1x_open = false;
        spin_unlock_bh(&txdata->lock);
        wil_vring_free(wil, vring, 1);
 out:

        return rc;
}

void wil_vring_fini_tx(struct wil6210_priv *wil, int id)
{
        struct vring *vring = &wil->vring_tx[id];
        struct vring_tx_data *txdata = &wil->vring_tx_data[id];

        lockdep_assert_held(&wil->mutex);

        if (!vring->va)
                return;

        wil_dbg_misc(wil, "vring_fini_tx: id=%d\n", id);

        spin_lock_bh(&txdata->lock);
        txdata->dot1x_open = false;
        txdata->mid = U8_MAX;
        txdata->enabled = 0; /* no Tx can be in progress or start anew */
        spin_unlock_bh(&txdata->lock);
        /* napi_synchronize waits for completion of the current NAPI but will
         * not prevent the next NAPI run.
         * Add a memory barrier to guarantee that txdata->enabled is zeroed
         * before napi_synchronize so that the next scheduled NAPI will not
         * handle this vring
         */
        wmb();
        /* make sure NAPI won't touch this vring */
        if (test_bit(wil_status_napi_en, wil->status))
                napi_synchronize(&wil->napi_tx);

        wil_vring_free(wil, vring, 1);
}

static struct vring *wil_find_tx_ucast(struct wil6210_priv *wil,
                                       struct wil6210_vif *vif,
                                       struct sk_buff *skb)
{
        int i;
        struct ethhdr *eth = (void *)skb->data;
        int cid = wil_find_cid(wil, vif->mid, eth->h_dest);

        if (cid < 0)
                return NULL;

        /* TODO: fix for multiple TID */
        for (i = 0; i < ARRAY_SIZE(wil->vring2cid_tid); i++) {
                if (!wil->vring_tx_data[i].dot1x_open &&
                    (skb->protocol != cpu_to_be16(ETH_P_PAE)))
                        continue;
                if (wil->vring2cid_tid[i][0] == cid) {
                        struct vring *v = &wil->vring_tx[i];
                        struct vring_tx_data *txdata = &wil->vring_tx_data[i];

                        wil_dbg_txrx(wil, "find_tx_ucast: (%pM) -> [%d]\n",
                                     eth->h_dest, i);
                        if (v->va && txdata->enabled) {
                                return v;
                        } else {
                                wil_dbg_txrx(wil,
                                             "find_tx_ucast: vring[%d] not valid\n",
                                             i);
                                return NULL;
                        }
                }
        }

        return NULL;
}

static int wil_tx_vring(struct wil6210_priv *wil, struct wil6210_vif *vif,
                        struct vring *vring, struct sk_buff *skb);

static struct vring *wil_find_tx_vring_sta(struct wil6210_priv *wil,
                                           struct wil6210_vif *vif,
                                           struct sk_buff *skb)
{
        struct vring *v;
        int i;
        u8 cid;
        struct vring_tx_data *txdata;

        /* In the STA mode, it is expected to have only 1 VRING
         * for the AP we connected to.
         * find 1-st vring eligible for this skb and use it.
         */
        for (i = 0; i < WIL6210_MAX_TX_RINGS; i++) {
                v = &wil->vring_tx[i];
                txdata = &wil->vring_tx_data[i];
                if (!v->va || !txdata->enabled || txdata->mid != vif->mid)
                        continue;

                cid = wil->vring2cid_tid[i][0];
                if (cid >= WIL6210_MAX_CID) /* skip BCAST */
                        continue;

                if (!wil->vring_tx_data[i].dot1x_open &&
                    (skb->protocol != cpu_to_be16(ETH_P_PAE)))
                        continue;

                wil_dbg_txrx(wil, "Tx -> ring %d\n", i);

                return v;
        }

        wil_dbg_txrx(wil, "Tx while no vrings active?\n");

        return NULL;
}

/* Use one of 2 strategies:
 *
 * 1. New (real broadcast):
 *    use dedicated broadcast vring
 * 2. Old (pseudo-DMS):
 *    Find 1-st vring and return it;
 *    duplicate skb and send it to other active vrings;
 *    in all cases override dest address to unicast peer's address
 * Use old strategy when new is not supported yet:
 *  - for PBSS
 */
static struct vring *wil_find_tx_bcast_1(struct wil6210_priv *wil,
                                         struct wil6210_vif *vif,
                                         struct sk_buff *skb)
{
        struct vring *v;
        struct vring_tx_data *txdata;
        int i = vif->bcast_vring;

        if (i < 0)
                return NULL;
        v = &wil->vring_tx[i];
        txdata = &wil->vring_tx_data[i];
        if (!v->va || !txdata->enabled)
                return NULL;
        if (!wil->vring_tx_data[i].dot1x_open &&
            (skb->protocol != cpu_to_be16(ETH_P_PAE)))
                return NULL;

        return v;
}

static void wil_set_da_for_vring(struct wil6210_priv *wil,
                                 struct sk_buff *skb, int vring_index)
{
        struct ethhdr *eth = (void *)skb->data;
        int cid = wil->vring2cid_tid[vring_index][0];

        ether_addr_copy(eth->h_dest, wil->sta[cid].addr);
}

static struct vring *wil_find_tx_bcast_2(struct wil6210_priv *wil,
                                         struct wil6210_vif *vif,
                                         struct sk_buff *skb)
{
        struct vring *v, *v2;
        struct sk_buff *skb2;
        int i;
        u8 cid;
        struct ethhdr *eth = (void *)skb->data;
        char *src = eth->h_source;
        struct vring_tx_data *txdata, *txdata2;

        /* find 1-st vring eligible for data */
        for (i = 0; i < WIL6210_MAX_TX_RINGS; i++) {
                v = &wil->vring_tx[i];
                txdata = &wil->vring_tx_data[i];
                if (!v->va || !txdata->enabled || txdata->mid != vif->mid)
                        continue;

                cid = wil->vring2cid_tid[i][0];
                if (cid >= WIL6210_MAX_CID) /* skip BCAST */
                        continue;
                if (!wil->vring_tx_data[i].dot1x_open &&
                    (skb->protocol != cpu_to_be16(ETH_P_PAE)))
                        continue;

                /* don't Tx back to source when re-routing Rx->Tx at the AP */
                if (0 == memcmp(wil->sta[cid].addr, src, ETH_ALEN))
                        continue;

                goto found;
        }

        wil_dbg_txrx(wil, "Tx while no vrings active?\n");

        return NULL;

found:
        wil_dbg_txrx(wil, "BCAST -> ring %d\n", i);
        wil_set_da_for_vring(wil, skb, i);

        /* find other active vrings and duplicate skb for each */
        for (i++; i < WIL6210_MAX_TX_RINGS; i++) {
                v2 = &wil->vring_tx[i];
                txdata2 = &wil->vring_tx_data[i];
                if (!v2->va || txdata2->mid != vif->mid)
                        continue;
                cid = wil->vring2cid_tid[i][0];
                if (cid >= WIL6210_MAX_CID) /* skip BCAST */
                        continue;
                if (!wil->vring_tx_data[i].dot1x_open &&
                    (skb->protocol != cpu_to_be16(ETH_P_PAE)))
                        continue;

                if (0 == memcmp(wil->sta[cid].addr, src, ETH_ALEN))
                        continue;

                skb2 = skb_copy(skb, GFP_ATOMIC);
                if (skb2) {
                        wil_dbg_txrx(wil, "BCAST DUP -> ring %d\n", i);
                        wil_set_da_for_vring(wil, skb2, i);
                        wil_tx_vring(wil, vif, v2, skb2);
                } else {
                        wil_err(wil, "skb_copy failed\n");
                }
        }

        return v;
}

static int wil_tx_desc_map(struct vring_tx_desc *d, dma_addr_t pa, u32 len,
                           int vring_index)
{
        wil_desc_addr_set(&d->dma.addr, pa);
        d->dma.ip_length = 0;
        /* 0..6: mac_length; 7:ip_version 0-IP6 1-IP4*/
        d->dma.b11 = 0/*14 | BIT(7)*/;
        d->dma.error = 0;
        d->dma.status = 0; /* BIT(0) should be 0 for HW_OWNED */
        d->dma.length = cpu_to_le16((u16)len);
        d->dma.d0 = (vring_index << DMA_CFG_DESC_TX_0_QID_POS);
        d->mac.d[0] = 0;
        d->mac.d[1] = 0;
        d->mac.d[2] = 0;
        d->mac.ucode_cmd = 0;
        /* translation type:  0 - bypass; 1 - 802.3; 2 - native wifi */
        d->mac.d[2] = BIT(MAC_CFG_DESC_TX_2_SNAP_HDR_INSERTION_EN_POS) |
                      (1 << MAC_CFG_DESC_TX_2_L2_TRANSLATION_TYPE_POS);

        return 0;
}

static inline
void wil_tx_desc_set_nr_frags(struct vring_tx_desc *d, int nr_frags)
{
        d->mac.d[2] |= (nr_frags << MAC_CFG_DESC_TX_2_NUM_OF_DESCRIPTORS_POS);
}

/**
 * Sets the descriptor @d up for csum and/or TSO offloading. The corresponding
 * @skb is used to obtain the protocol and headers length.
 * @tso_desc_type is a descriptor type for TSO: 0 - a header, 1 - first data,
 * 2 - middle, 3 - last descriptor.
 */

static void wil_tx_desc_offload_setup_tso(struct vring_tx_desc *d,
                                          struct sk_buff *skb,
                                          int tso_desc_type, bool is_ipv4,
                                          int tcp_hdr_len, int skb_net_hdr_len)
{
        d->dma.b11 = ETH_HLEN; /* MAC header length */
        d->dma.b11 |= is_ipv4 << DMA_CFG_DESC_TX_OFFLOAD_CFG_L3T_IPV4_POS;

        d->dma.d0 |= (2 << DMA_CFG_DESC_TX_0_L4_TYPE_POS);
        /* L4 header len: TCP header length */
        d->dma.d0 |= (tcp_hdr_len & DMA_CFG_DESC_TX_0_L4_LENGTH_MSK);

        /* Setup TSO: bit and desc type */
        d->dma.d0 |= (BIT(DMA_CFG_DESC_TX_0_TCP_SEG_EN_POS)) |
                (tso_desc_type << DMA_CFG_DESC_TX_0_SEGMENT_BUF_DETAILS_POS);
        d->dma.d0 |= (is_ipv4 << DMA_CFG_DESC_TX_0_IPV4_CHECKSUM_EN_POS);

        d->dma.ip_length = skb_net_hdr_len;
        /* Enable TCP/UDP checksum */
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_TCP_UDP_CHECKSUM_EN_POS);
        /* Calculate pseudo-header */
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_PSEUDO_HEADER_CALC_EN_POS);
}

/**
 * Sets the descriptor @d up for csum. The corresponding
 * @skb is used to obtain the protocol and headers length.
 * Returns the protocol: 0 - not TCP, 1 - TCPv4, 2 - TCPv6.
 * Note, if d==NULL, the function only returns the protocol result.
 *
 * It is very similar to previous wil_tx_desc_offload_setup_tso. This
 * is "if unrolling" to optimize the critical path.
 */

static int wil_tx_desc_offload_setup(struct vring_tx_desc *d,
                                     struct sk_buff *skb){
        int protocol;

        if (skb->ip_summed != CHECKSUM_PARTIAL)
                return 0;

        d->dma.b11 = ETH_HLEN; /* MAC header length */

        switch (skb->protocol) {
        case cpu_to_be16(ETH_P_IP):
                protocol = ip_hdr(skb)->protocol;
                d->dma.b11 |= BIT(DMA_CFG_DESC_TX_OFFLOAD_CFG_L3T_IPV4_POS);
                break;
        case cpu_to_be16(ETH_P_IPV6):
                protocol = ipv6_hdr(skb)->nexthdr;
                break;
        default:
                return -EINVAL;
        }

        switch (protocol) {
        case IPPROTO_TCP:
                d->dma.d0 |= (2 << DMA_CFG_DESC_TX_0_L4_TYPE_POS);
                /* L4 header len: TCP header length */
                d->dma.d0 |=
                (tcp_hdrlen(skb) & DMA_CFG_DESC_TX_0_L4_LENGTH_MSK);
                break;
        case IPPROTO_UDP:
                /* L4 header len: UDP header length */
                d->dma.d0 |=
                (sizeof(struct udphdr) & DMA_CFG_DESC_TX_0_L4_LENGTH_MSK);
                break;
        default:
                return -EINVAL;
        }

        d->dma.ip_length = skb_network_header_len(skb);
        /* Enable TCP/UDP checksum */
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_TCP_UDP_CHECKSUM_EN_POS);
        /* Calculate pseudo-header */
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_PSEUDO_HEADER_CALC_EN_POS);

        return 0;
}

static inline void wil_tx_last_desc(struct vring_tx_desc *d)
{
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_CMD_EOP_POS) |
              BIT(DMA_CFG_DESC_TX_0_CMD_MARK_WB_POS) |
              BIT(DMA_CFG_DESC_TX_0_CMD_DMA_IT_POS);
}

static inline void wil_set_tx_desc_last_tso(volatile struct vring_tx_desc *d)
{
        d->dma.d0 |= wil_tso_type_lst <<
                  DMA_CFG_DESC_TX_0_SEGMENT_BUF_DETAILS_POS;
}

static int __wil_tx_vring_tso(struct wil6210_priv *wil, struct wil6210_vif *vif,
                              struct vring *vring, struct sk_buff *skb)
{
        struct device *dev = wil_to_dev(wil);

        /* point to descriptors in shared memory */
        volatile struct vring_tx_desc *_desc = NULL, *_hdr_desc,
                                      *_first_desc = NULL;

        /* pointers to shadow descriptors */
        struct vring_tx_desc desc_mem, hdr_desc_mem, first_desc_mem,
                             *d = &hdr_desc_mem, *hdr_desc = &hdr_desc_mem,
                             *first_desc = &first_desc_mem;

        /* pointer to shadow descriptors' context */
        struct wil_ctx *hdr_ctx, *first_ctx = NULL;

        int descs_used = 0; /* total number of used descriptors */
        int sg_desc_cnt = 0; /* number of descriptors for current mss*/

        u32 swhead = vring->swhead;
        int used, avail = wil_vring_avail_tx(vring);
        int nr_frags = skb_shinfo(skb)->nr_frags;
        int min_desc_required = nr_frags + 1;
        int mss = skb_shinfo(skb)->gso_size;    /* payload size w/o headers */
        int f, len, hdrlen, headlen;
        int vring_index = vring - wil->vring_tx;
        struct vring_tx_data *txdata = &wil->vring_tx_data[vring_index];
        uint i = swhead;
        dma_addr_t pa;
        const skb_frag_t *frag = NULL;
        int rem_data = mss;
        int lenmss;
        int hdr_compensation_need = true;
        int desc_tso_type = wil_tso_type_first;
        bool is_ipv4;
        int tcp_hdr_len;
        int skb_net_hdr_len;
        int gso_type;
        int rc = -EINVAL;

        wil_dbg_txrx(wil, "tx_vring_tso: %d bytes to vring %d\n", skb->len,
                     vring_index);

        if (unlikely(!txdata->enabled))
                return -EINVAL;

        /* A typical page 4K is 3-4 payloads, we assume each fragment
         * is a full payload, that's how min_desc_required has been
         * calculated. In real we might need more or less descriptors,
         * this is the initial check only.
         */
        if (unlikely(avail < min_desc_required)) {
                wil_err_ratelimited(wil,
                                    "TSO: Tx ring[%2d] full. No space for %d fragments\n",
                                    vring_index, min_desc_required);
                return -ENOMEM;
        }

        /* Header Length = MAC header len + IP header len + TCP header len*/
        hdrlen = ETH_HLEN +
                (int)skb_network_header_len(skb) +
                tcp_hdrlen(skb);

        gso_type = skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV6 | SKB_GSO_TCPV4);
        switch (gso_type) {
        case SKB_GSO_TCPV4:
                /* TCP v4, zero out the IP length and IPv4 checksum fields
                 * as required by the offloading doc
                 */
                ip_hdr(skb)->tot_len = 0;
                ip_hdr(skb)->check = 0;
                is_ipv4 = true;
                break;
        case SKB_GSO_TCPV6:
                /* TCP v6, zero out the payload length */
                ipv6_hdr(skb)->payload_len = 0;
                is_ipv4 = false;
                break;
        default:
                /* other than TCPv4 or TCPv6 types are not supported for TSO.
                 * It is also illegal for both to be set simultaneously
                 */
                return -EINVAL;
        }

        if (skb->ip_summed != CHECKSUM_PARTIAL)
                return -EINVAL;

        /* tcp header length and skb network header length are fixed for all
         * packet's descriptors - read then once here
         */
        tcp_hdr_len = tcp_hdrlen(skb);
        skb_net_hdr_len = skb_network_header_len(skb);

        _hdr_desc = &vring->va[i].tx;

        pa = dma_map_single(dev, skb->data, hdrlen, DMA_TO_DEVICE);
        if (unlikely(dma_mapping_error(dev, pa))) {
                wil_err(wil, "TSO: Skb head DMA map error\n");
                goto err_exit;
        }

        wil_tx_desc_map(hdr_desc, pa, hdrlen, vring_index);
        wil_tx_desc_offload_setup_tso(hdr_desc, skb, wil_tso_type_hdr, is_ipv4,
                                      tcp_hdr_len, skb_net_hdr_len);
        wil_tx_last_desc(hdr_desc);

        vring->ctx[i].mapped_as = wil_mapped_as_single;
        hdr_ctx = &vring->ctx[i];

        descs_used++;
        headlen = skb_headlen(skb) - hdrlen;

        for (f = headlen ? -1 : 0; f < nr_frags; f++)  {
                if (headlen) {
                        len = headlen;
                        wil_dbg_txrx(wil, "TSO: process skb head, len %u\n",
                                     len);
                } else {
                        frag = &skb_shinfo(skb)->frags[f];
                        len = frag->size;
                        wil_dbg_txrx(wil, "TSO: frag[%d]: len %u\n", f, len);
                }

                while (len) {
                        wil_dbg_txrx(wil,
                                     "TSO: len %d, rem_data %d, descs_used %d\n",
                                     len, rem_data, descs_used);

                        if (descs_used == avail)  {
                                wil_err_ratelimited(wil, "TSO: ring overflow\n");
                                rc = -ENOMEM;
                                goto mem_error;
                        }

                        lenmss = min_t(int, rem_data, len);
                        i = (swhead + descs_used) % vring->size;
                        wil_dbg_txrx(wil, "TSO: lenmss %d, i %d\n", lenmss, i);

                        if (!headlen) {
                                pa = skb_frag_dma_map(dev, frag,
                                                      frag->size - len, lenmss,
                                                      DMA_TO_DEVICE);
                                vring->ctx[i].mapped_as = wil_mapped_as_page;
                        } else {
                                pa = dma_map_single(dev,
                                                    skb->data +
                                                    skb_headlen(skb) - headlen,
                                                    lenmss,
                                                    DMA_TO_DEVICE);
                                vring->ctx[i].mapped_as = wil_mapped_as_single;
                                headlen -= lenmss;
                        }

                        if (unlikely(dma_mapping_error(dev, pa))) {
                                wil_err(wil, "TSO: DMA map page error\n");
                                goto mem_error;
                        }

                        _desc = &vring->va[i].tx;

                        if (!_first_desc) {
                                _first_desc = _desc;
                                first_ctx = &vring->ctx[i];
                                d = first_desc;
                        } else {
                                d = &desc_mem;
                        }

                        wil_tx_desc_map(d, pa, lenmss, vring_index);
                        wil_tx_desc_offload_setup_tso(d, skb, desc_tso_type,
                                                      is_ipv4, tcp_hdr_len,
                                                      skb_net_hdr_len);

                        /* use tso_type_first only once */
                        desc_tso_type = wil_tso_type_mid;

                        descs_used++;  /* desc used so far */
                        sg_desc_cnt++; /* desc used for this segment */
                        len -= lenmss;
                        rem_data -= lenmss;

                        wil_dbg_txrx(wil,
                                     "TSO: len %d, rem_data %d, descs_used %d, sg_desc_cnt %d,\n",
                                     len, rem_data, descs_used, sg_desc_cnt);

                        /* Close the segment if reached mss size or last frag*/
                        if (rem_data == 0 || (f == nr_frags - 1 && len == 0)) {
                                if (hdr_compensation_need) {
                                        /* first segment include hdr desc for
                                         * release
                                         */
                                        hdr_ctx->nr_frags = sg_desc_cnt;
                                        wil_tx_desc_set_nr_frags(first_desc,
                                                                 sg_desc_cnt +
                                                                 1);
                                        hdr_compensation_need = false;
                                } else {
                                        wil_tx_desc_set_nr_frags(first_desc,
                                                                 sg_desc_cnt);
                                }
                                first_ctx->nr_frags = sg_desc_cnt - 1;

                                wil_tx_last_desc(d);

                                /* first descriptor may also be the last
                                 * for this mss - make sure not to copy
                                 * it twice
                                 */
                                if (first_desc != d)
                                        *_first_desc = *first_desc;

                                /*last descriptor will be copied at the end
                                 * of this TS processing
                                 */
                                if (f < nr_frags - 1 || len > 0)
                                        *_desc = *d;

                                rem_data = mss;
                                _first_desc = NULL;
                                sg_desc_cnt = 0;
                        } else if (first_desc != d) /* update mid descriptor */
                                        *_desc = *d;
                }
        }

        /* first descriptor may also be the last.
         * in this case d pointer is invalid
         */
        if (_first_desc == _desc)
                d = first_desc;

        /* Last data descriptor */
        wil_set_tx_desc_last_tso(d);
        *_desc = *d;

        /* Fill the total number of descriptors in first desc (hdr)*/
        wil_tx_desc_set_nr_frags(hdr_desc, descs_used);
        *_hdr_desc = *hdr_desc;

        /* hold reference to skb
         * to prevent skb release before accounting
         * in case of immediate "tx done"
         */
        vring->ctx[i].skb = skb_get(skb);

        /* performance monitoring */
        used = wil_vring_used_tx(vring);
        if (wil_val_in_range(wil->vring_idle_trsh,
                             used, used + descs_used)) {
                txdata->idle += get_cycles() - txdata->last_idle;
                wil_dbg_txrx(wil,  "Ring[%2d] not idle %d -> %d\n",
                             vring_index, used, used + descs_used);
        }

        /* Make sure to advance the head only after descriptor update is done.
         * This will prevent a race condition where the completion thread
         * will see the DU bit set from previous run and will handle the
         * skb before it was completed.
         */
        wmb();

        /* advance swhead */
        wil_vring_advance_head(vring, descs_used);
        wil_dbg_txrx(wil, "TSO: Tx swhead %d -> %d\n", swhead, vring->swhead);

        /* make sure all writes to descriptors (shared memory) are done before
         * committing them to HW
         */
        wmb();

        wil_w(wil, vring->hwtail, vring->swhead);
        return 0;

mem_error:
        while (descs_used > 0) {
                struct wil_ctx *ctx;

                i = (swhead + descs_used - 1) % vring->size;
                d = (struct vring_tx_desc *)&vring->va[i].tx;
                _desc = &vring->va[i].tx;
                *d = *_desc;
                _desc->dma.status = TX_DMA_STATUS_DU;
                ctx = &vring->ctx[i];
                wil_txdesc_unmap(dev, d, ctx);
                memset(ctx, 0, sizeof(*ctx));
                descs_used--;
        }
err_exit:
        return rc;
}

static int __wil_tx_vring(struct wil6210_priv *wil, struct wil6210_vif *vif,
                          struct vring *vring, struct sk_buff *skb)
{
        struct device *dev = wil_to_dev(wil);
        struct vring_tx_desc dd, *d = &dd;
        volatile struct vring_tx_desc *_d;
        u32 swhead = vring->swhead;
        int avail = wil_vring_avail_tx(vring);
        int nr_frags = skb_shinfo(skb)->nr_frags;
        uint f = 0;
        int vring_index = vring - wil->vring_tx;
        struct vring_tx_data *txdata = &wil->vring_tx_data[vring_index];
        uint i = swhead;
        dma_addr_t pa;
        int used;
        bool mcast = (vring_index == vif->bcast_vring);
        uint len = skb_headlen(skb);

        wil_dbg_txrx(wil, "tx_vring: %d bytes to vring %d\n", skb->len,
                     vring_index);

        if (unlikely(!txdata->enabled))
                return -EINVAL;

        if (unlikely(avail < 1 + nr_frags)) {
                wil_err_ratelimited(wil,
                                    "Tx ring[%2d] full. No space for %d fragments\n",
                                    vring_index, 1 + nr_frags);
                return -ENOMEM;
        }
        _d = &vring->va[i].tx;

        pa = dma_map_single(dev, skb->data, skb_headlen(skb), DMA_TO_DEVICE);

        wil_dbg_txrx(wil, "Tx[%2d] skb %d bytes 0x%p -> %pad\n", vring_index,
                     skb_headlen(skb), skb->data, &pa);
        wil_hex_dump_txrx("Tx ", DUMP_PREFIX_OFFSET, 16, 1,
                          skb->data, skb_headlen(skb), false);

        if (unlikely(dma_mapping_error(dev, pa)))
                return -EINVAL;
        vring->ctx[i].mapped_as = wil_mapped_as_single;
        /* 1-st segment */
        wil_tx_desc_map(d, pa, len, vring_index);
        if (unlikely(mcast)) {
                d->mac.d[0] |= BIT(MAC_CFG_DESC_TX_0_MCS_EN_POS); /* MCS 0 */
                if (unlikely(len > WIL_BCAST_MCS0_LIMIT)) /* set MCS 1 */
                        d->mac.d[0] |= (1 << MAC_CFG_DESC_TX_0_MCS_INDEX_POS);
        }
        /* Process TCP/UDP checksum offloading */
        if (unlikely(wil_tx_desc_offload_setup(d, skb))) {
                wil_err(wil, "Tx[%2d] Failed to set cksum, drop packet\n",
                        vring_index);
                goto dma_error;
        }

        vring->ctx[i].nr_frags = nr_frags;
        wil_tx_desc_set_nr_frags(d, nr_frags + 1);

        /* middle segments */
        for (; f < nr_frags; f++) {
                const struct skb_frag_struct *frag =
                                &skb_shinfo(skb)->frags[f];
                int len = skb_frag_size(frag);

                *_d = *d;
                wil_dbg_txrx(wil, "Tx[%2d] desc[%4d]\n", vring_index, i);
                wil_hex_dump_txrx("TxD ", DUMP_PREFIX_NONE, 32, 4,
                                  (const void *)d, sizeof(*d), false);
                i = (swhead + f + 1) % vring->size;
                _d = &vring->va[i].tx;
                pa = skb_frag_dma_map(dev, frag, 0, skb_frag_size(frag),
                                      DMA_TO_DEVICE);
                if (unlikely(dma_mapping_error(dev, pa))) {
                        wil_err(wil, "Tx[%2d] failed to map fragment\n",
                                vring_index);
                        goto dma_error;
                }
                vring->ctx[i].mapped_as = wil_mapped_as_page;
                wil_tx_desc_map(d, pa, len, vring_index);
                /* no need to check return code -
                 * if it succeeded for 1-st descriptor,
                 * it will succeed here too
                 */
                wil_tx_desc_offload_setup(d, skb);
        }
        /* for the last seg only */
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_CMD_EOP_POS);
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_CMD_MARK_WB_POS);
        d->dma.d0 |= BIT(DMA_CFG_DESC_TX_0_CMD_DMA_IT_POS);
        *_d = *d;
        wil_dbg_txrx(wil, "Tx[%2d] desc[%4d]\n", vring_index, i);
        wil_hex_dump_txrx("TxD ", DUMP_PREFIX_NONE, 32, 4,
                          (const void *)d, sizeof(*d), false);

        /* hold reference to skb
         * to prevent skb release before accounting
         * in case of immediate "tx done"
         */
        vring->ctx[i].skb = skb_get(skb);

        /* performance monitoring */
        used = wil_vring_used_tx(vring);
        if (wil_val_in_range(wil->vring_idle_trsh,
                             used, used + nr_frags + 1)) {
                txdata->idle += get_cycles() - txdata->last_idle;
                wil_dbg_txrx(wil,  "Ring[%2d] not idle %d -> %d\n",
                             vring_index, used, used + nr_frags + 1);
        }

        /* Make sure to advance the head only after descriptor update is done.
         * This will prevent a race condition where the completion thread
         * will see the DU bit set from previous run and will handle the
         * skb before it was completed.
         */
        wmb();

        /* advance swhead */
        wil_vring_advance_head(vring, nr_frags + 1);
        wil_dbg_txrx(wil, "Tx[%2d] swhead %d -> %d\n", vring_index, swhead,
                     vring->swhead);
        trace_wil6210_tx(vring_index, swhead, skb->len, nr_frags);

        /* make sure all writes to descriptors (shared memory) are done before
         * committing them to HW
         */
        wmb();

        wil_w(wil, vring->hwtail, vring->swhead);

        return 0;
 dma_error:
        /* unmap what we have mapped */
        nr_frags = f + 1; /* frags mapped + one for skb head */
        for (f = 0; f < nr_frags; f++) {
                struct wil_ctx *ctx;

                i = (swhead + f) % vring->size;
                ctx = &vring->ctx[i];
                _d = &vring->va[i].tx;
                *d = *_d;
                _d->dma.status = TX_DMA_STATUS_DU;
                wil_txdesc_unmap(dev, d, ctx);

                memset(ctx, 0, sizeof(*ctx));
        }

        return -EINVAL;
}

static int wil_tx_vring(struct wil6210_priv *wil, struct wil6210_vif *vif,
                        struct vring *vring, struct sk_buff *skb)
{
        int vring_index = vring - wil->vring_tx;
        struct vring_tx_data *txdata = &wil->vring_tx_data[vring_index];
        int rc;

        spin_lock(&txdata->lock);

        if (test_bit(wil_status_suspending, wil->status) ||
            test_bit(wil_status_suspended, wil->status) ||
            test_bit(wil_status_resuming, wil->status)) {
                wil_dbg_txrx(wil,
                             "suspend/resume in progress. drop packet\n");
                spin_unlock(&txdata->lock);
                return -EINVAL;
        }

        rc = (skb_is_gso(skb) ? __wil_tx_vring_tso : __wil_tx_vring)
             (wil, vif, vring, skb);

        spin_unlock(&txdata->lock);

        return rc;
}

/**
 * Check status of tx vrings and stop/wake net queues if needed
 * It will start/stop net queues of a specific VIF net_device.
 *
 * This function does one of two checks:
 * In case check_stop is true, will check if net queues need to be stopped. If
 * the conditions for stopping are met, netif_tx_stop_all_queues() is called.
 * In case check_stop is false, will check if net queues need to be waked. If
 * the conditions for waking are met, netif_tx_wake_all_queues() is called.
 * vring is the vring which is currently being modified by either adding
 * descriptors (tx) into it or removing descriptors (tx complete) from it. Can
 * be null when irrelevant (e.g. connect/disconnect events).
 *
 * The implementation is to stop net queues if modified vring has low
 * descriptor availability. Wake if all vrings are not in low descriptor
 * availability and modified vring has high descriptor availability.
 */
static inline void __wil_update_net_queues(struct wil6210_priv *wil,
                                           struct wil6210_vif *vif,
                                           struct vring *vring,
                                           bool check_stop)
{
        int i;

        if (unlikely(!vif))
                return;

        if (vring)
                wil_dbg_txrx(wil, "vring %d, mid %d, check_stop=%d, stopped=%d",
                             (int)(vring - wil->vring_tx), vif->mid, check_stop,
                             vif->net_queue_stopped);
        else
                wil_dbg_txrx(wil, "check_stop=%d, mid=%d, stopped=%d",
                             check_stop, vif->mid, vif->net_queue_stopped);

        if (check_stop == vif->net_queue_stopped)
                /* net queues already in desired state */
                return;

        if (check_stop) {
                if (!vring || unlikely(wil_vring_avail_low(vring))) {
                        /* not enough room in the vring */
                        netif_tx_stop_all_queues(vif_to_ndev(vif));
                        vif->net_queue_stopped = true;
                        wil_dbg_txrx(wil, "netif_tx_stop called\n");
                }
                return;
        }

        /* Do not wake the queues in suspend flow */
        if (test_bit(wil_status_suspending, wil->status) ||
            test_bit(wil_status_suspended, wil->status))
                return;

        /* check wake */
        for (i = 0; i < WIL6210_MAX_TX_RINGS; i++) {
                struct vring *cur_vring = &wil->vring_tx[i];
                struct vring_tx_data *txdata = &wil->vring_tx_data[i];

                if (txdata->mid != vif->mid || !cur_vring->va ||
                    !txdata->enabled || cur_vring == vring)
                        continue;

                if (wil_vring_avail_low(cur_vring)) {
                        wil_dbg_txrx(wil, "vring %d full, can't wake\n",
                                     (int)(cur_vring - wil->vring_tx));
                        return;
                }
        }

        if (!vring || wil_vring_avail_high(vring)) {
                /* enough room in the vring */
                wil_dbg_txrx(wil, "calling netif_tx_wake\n");
                netif_tx_wake_all_queues(vif_to_ndev(vif));
                vif->net_queue_stopped = false;
        }

}

void wil_update_net_queues(struct wil6210_priv *wil, struct wil6210_vif *vif,
                           struct vring *vring, bool check_stop)
{
        spin_lock(&wil->net_queue_lock);
        __wil_update_net_queues(wil, vif, vring, check_stop);
        spin_unlock(&wil->net_queue_lock);
}

void wil_update_net_queues_bh(struct wil6210_priv *wil, struct wil6210_vif *vif,
                              struct vring *vring, bool check_stop)
{
        spin_lock_bh(&wil->net_queue_lock);
        __wil_update_net_queues(wil, vif, vring, check_stop);
        spin_unlock_bh(&wil->net_queue_lock);
}

netdev_tx_t wil_start_xmit(struct sk_buff *skb, struct net_device *ndev)
{
        struct wil6210_vif *vif = ndev_to_vif(ndev);
        struct wil6210_priv *wil = vif_to_wil(vif);
        struct ethhdr *eth = (void *)skb->data;
        bool bcast = is_multicast_ether_addr(eth->h_dest);
        struct vring *vring;
        static bool pr_once_fw;
        int rc;

        wil_dbg_txrx(wil, "start_xmit\n");
        if (unlikely(!test_bit(wil_status_fwready, wil->status))) {
                if (!pr_once_fw) {
                        wil_err(wil, "FW not ready\n");
                        pr_once_fw = true;
                }
                goto drop;
        }
        if (unlikely(!test_bit(wil_vif_fwconnected, vif->status))) {
                wil_dbg_ratelimited(wil,
                                    "VIF not connected, packet dropped\n");
                goto drop;
        }
        if (unlikely(vif->wdev.iftype == NL80211_IFTYPE_MONITOR)) {
                wil_err(wil, "Xmit in monitor mode not supported\n");
                goto drop;
        }
        pr_once_fw = false;

        /* find vring */
        if (vif->wdev.iftype == NL80211_IFTYPE_STATION && !vif->pbss) {
                /* in STA mode (ESS), all to same VRING (to AP) */
                vring = wil_find_tx_vring_sta(wil, vif, skb);
        } else if (bcast) {
                if (vif->pbss)
                        /* in pbss, no bcast VRING - duplicate skb in
                         * all stations VRINGs
                         */
                        vring = wil_find_tx_bcast_2(wil, vif, skb);
                else if (vif->wdev.iftype == NL80211_IFTYPE_AP)
                        /* AP has a dedicated bcast VRING */
                        vring = wil_find_tx_bcast_1(wil, vif, skb);
                else
                        /* unexpected combination, fallback to duplicating
                         * the skb in all stations VRINGs
                         */
                        vring = wil_find_tx_bcast_2(wil, vif, skb);
        } else {
                /* unicast, find specific VRING by dest. address */
                vring = wil_find_tx_ucast(wil, vif, skb);
        }
        if (unlikely(!vring)) {
                wil_dbg_txrx(wil, "No Tx VRING found for %pM\n", eth->h_dest);
                goto drop;
        }
        /* set up vring entry */
        rc = wil_tx_vring(wil, vif, vring, skb);

        switch (rc) {
        case 0:
                /* shall we stop net queues? */
                wil_update_net_queues_bh(wil, vif, vring, true);
                /* statistics will be updated on the tx_complete */
                dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        case -ENOMEM:
                return NETDEV_TX_BUSY;
        default:
                break; /* goto drop; */
        }
 drop:
        ndev->stats.tx_dropped++;
        dev_kfree_skb_any(skb);

        return NET_XMIT_DROP;
}

static inline bool wil_need_txstat(struct sk_buff *skb)
{
        struct ethhdr *eth = (void *)skb->data;

        return is_unicast_ether_addr(eth->h_dest) && skb->sk &&
               (skb_shinfo(skb)->tx_flags & SKBTX_WIFI_STATUS);
}

static inline void wil_consume_skb(struct sk_buff *skb, bool acked)
{
        if (unlikely(wil_need_txstat(skb)))
                skb_complete_wifi_ack(skb, acked);
        else
                acked ? dev_consume_skb_any(skb) : dev_kfree_skb_any(skb);
}

/**
 * Clean up transmitted skb's from the Tx VRING
 *
 * Return number of descriptors cleared
 *
 * Safe to call from IRQ
 */
int wil_tx_complete(struct wil6210_vif *vif, int ringid)
{
        struct wil6210_priv *wil = vif_to_wil(vif);
        struct net_device *ndev = vif_to_ndev(vif);
        struct device *dev = wil_to_dev(wil);
        struct vring *vring = &wil->vring_tx[ringid];
        struct vring_tx_data *txdata = &wil->vring_tx_data[ringid];
        int done = 0;
        int cid = wil->vring2cid_tid[ringid][0];
        struct wil_net_stats *stats = NULL;
        volatile struct vring_tx_desc *_d;
        int used_before_complete;
        int used_new;

        if (unlikely(!vring->va)) {
                wil_err(wil, "Tx irq[%d]: vring not initialized\n", ringid);
                return 0;
        }

        if (unlikely(!txdata->enabled)) {
                wil_info(wil, "Tx irq[%d]: vring disabled\n", ringid);
                return 0;
        }

        wil_dbg_txrx(wil, "tx_complete: (%d)\n", ringid);

        used_before_complete = wil_vring_used_tx(vring);

        if (cid < WIL6210_MAX_CID)
                stats = &wil->sta[cid].stats;

        while (!wil_vring_is_empty(vring)) {
                int new_swtail;
                struct wil_ctx *ctx = &vring->ctx[vring->swtail];
                /**
                 * For the fragmented skb, HW will set DU bit only for the
                 * last fragment. look for it.
                 * In TSO the first DU will include hdr desc
                 */
                int lf = (vring->swtail + ctx->nr_frags) % vring->size;
                /* TODO: check we are not past head */

                _d = &vring->va[lf].tx;
                if (unlikely(!(_d->dma.status & TX_DMA_STATUS_DU)))
                        break;

                new_swtail = (lf + 1) % vring->size;
                while (vring->swtail != new_swtail) {
                        struct vring_tx_desc dd, *d = &dd;
                        u16 dmalen;
                        struct sk_buff *skb;

                        ctx = &vring->ctx[vring->swtail];
                        skb = ctx->skb;
                        _d = &vring->va[vring->swtail].tx;

                        *d = *_d;

                        dmalen = le16_to_cpu(d->dma.length);
                        trace_wil6210_tx_done(ringid, vring->swtail, dmalen,
                                              d->dma.error);
                        wil_dbg_txrx(wil,
                                     "TxC[%2d][%3d] : %d bytes, status 0x%02x err 0x%02x\n",
                                     ringid, vring->swtail, dmalen,
                                     d->dma.status, d->dma.error);
                        wil_hex_dump_txrx("TxCD ", DUMP_PREFIX_NONE, 32, 4,
                                          (const void *)d, sizeof(*d), false);

                        wil_txdesc_unmap(dev, d, ctx);

                        if (skb) {
                                if (likely(d->dma.error == 0)) {
                                        ndev->stats.tx_packets++;
                                        ndev->stats.tx_bytes += skb->len;
                                        if (stats) {
                                                stats->tx_packets++;
                                                stats->tx_bytes += skb->len;
                                        }
                                } else {
                                        ndev->stats.tx_errors++;
                                        if (stats)
                                                stats->tx_errors++;
                                }
                                wil_consume_skb(skb, d->dma.error == 0);
                        }
                        memset(ctx, 0, sizeof(*ctx));
                        /* Make sure the ctx is zeroed before updating the tail
                         * to prevent a case where wil_tx_vring will see
                         * this descriptor as used and handle it before ctx zero
                         * is completed.
                         */
                        wmb();
                        /* There is no need to touch HW descriptor:
                         * - ststus bit TX_DMA_STATUS_DU is set by design,
                         *   so hardware will not try to process this desc.,
                         * - rest of descriptor will be initialized on Tx.
                         */
                        vring->swtail = wil_vring_next_tail(vring);
                        done++;
                }
        }

        /* performance monitoring */
        used_new = wil_vring_used_tx(vring);
        if (wil_val_in_range(wil->vring_idle_trsh,
                             used_new, used_before_complete)) {
                wil_dbg_txrx(wil, "Ring[%2d] idle %d -> %d\n",
                             ringid, used_before_complete, used_new);
                txdata->last_idle = get_cycles();
        }

        /* shall we wake net queues? */
        if (done)
                wil_update_net_queues(wil, vif, vring, false);

        return done;
}