// SPDX-License-Identifier: GPL-2.0+

#include <linux/bpf.h>
#include <linux/filter.h>
#include <net/page_pool/helpers.h>

#include "lan966x_main.h"

static int lan966x_fdma_rx_dataptr_cb(struct fdma *fdma, int dcb, int db,
                                      u64 *dataptr)
{
        struct lan966x *lan966x = (struct lan966x *)fdma->priv;
        struct lan966x_rx *rx = &lan966x->rx;
        struct page *page;

        page = page_pool_dev_alloc_pages(rx->page_pool);
        if (unlikely(!page))
                return -ENOMEM;

        rx->page[dcb][db] = page;
        *dataptr = page_pool_get_dma_addr(page) + XDP_PACKET_HEADROOM;

        return 0;
}

static int lan966x_fdma_tx_dataptr_cb(struct fdma *fdma, int dcb, int db,
                                      u64 *dataptr)
{
        struct lan966x *lan966x = (struct lan966x *)fdma->priv;

        *dataptr = lan966x->tx.dcbs_buf[dcb].dma_addr;

        return 0;
}

static int lan966x_fdma_xdp_tx_dataptr_cb(struct fdma *fdma, int dcb, int db,
                                          u64 *dataptr)
{
        struct lan966x *lan966x = (struct lan966x *)fdma->priv;

        *dataptr = lan966x->tx.dcbs_buf[dcb].dma_addr + XDP_PACKET_HEADROOM;

        return 0;
}

static int lan966x_fdma_channel_active(struct lan966x *lan966x)
{
        return lan_rd(lan966x, FDMA_CH_ACTIVE);
}

static void lan966x_fdma_rx_free_pages(struct lan966x_rx *rx)
{
        struct fdma *fdma = &rx->fdma;
        int i, j;

        for (i = 0; i < fdma->n_dcbs; ++i) {
                for (j = 0; j < fdma->n_dbs; ++j)
                        page_pool_put_full_page(rx->page_pool,
                                                rx->page[i][j], false);
        }
}

static void lan966x_fdma_rx_free_page(struct lan966x_rx *rx)
{
        struct fdma *fdma = &rx->fdma;
        struct page *page;

        page = rx->page[fdma->dcb_index][fdma->db_index];
        if (unlikely(!page))
                return;

        page_pool_recycle_direct(rx->page_pool, page);
}

static int lan966x_fdma_rx_alloc_page_pool(struct lan966x_rx *rx)
{
        struct lan966x *lan966x = rx->lan966x;
        struct page_pool_params pp_params = {
                .order = rx->page_order,
                .flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
                .pool_size = rx->fdma.n_dcbs,
                .nid = NUMA_NO_NODE,
                .dev = lan966x->dev,
                .dma_dir = DMA_FROM_DEVICE,
                .offset = XDP_PACKET_HEADROOM,
                .max_len = rx->max_mtu -
                           SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
        };

        if (lan966x_xdp_present(lan966x))
                pp_params.dma_dir = DMA_BIDIRECTIONAL;

        rx->page_pool = page_pool_create(&pp_params);
        if (IS_ERR(rx->page_pool))
                return PTR_ERR(rx->page_pool);

        for (int i = 0; i < lan966x->num_phys_ports; ++i) {
                struct lan966x_port *port;

                if (!lan966x->ports[i])
                        continue;

                port = lan966x->ports[i];
                xdp_rxq_info_unreg_mem_model(&port->xdp_rxq);
                xdp_rxq_info_reg_mem_model(&port->xdp_rxq, MEM_TYPE_PAGE_POOL,
                                           rx->page_pool);
        }

        return 0;
}

static int lan966x_fdma_rx_alloc(struct lan966x_rx *rx)
{
        struct lan966x *lan966x = rx->lan966x;
        struct fdma *fdma = &rx->fdma;
        int err;

        err = lan966x_fdma_rx_alloc_page_pool(rx);
        if (err)
                return err;

        err = fdma_alloc_coherent(lan966x->dev, fdma);
        if (err) {
                page_pool_destroy(rx->page_pool);
                return err;
        }

        fdma_dcbs_init(fdma, FDMA_DCB_INFO_DATAL(fdma->db_size),
                       FDMA_DCB_STATUS_INTR);

        return 0;
}

static void lan966x_fdma_rx_start(struct lan966x_rx *rx)
{
        struct lan966x *lan966x = rx->lan966x;
        struct fdma *fdma = &rx->fdma;
        u32 mask;

        /* When activating a channel, first is required to write the first DCB
         * address and then to activate it
         */
        lan_wr(lower_32_bits((u64)fdma->dma), lan966x,
               FDMA_DCB_LLP(fdma->channel_id));
        lan_wr(upper_32_bits((u64)fdma->dma), lan966x,
               FDMA_DCB_LLP1(fdma->channel_id));

        lan_wr(FDMA_CH_CFG_CH_DCB_DB_CNT_SET(fdma->n_dbs) |
               FDMA_CH_CFG_CH_INTR_DB_EOF_ONLY_SET(1) |
               FDMA_CH_CFG_CH_INJ_PORT_SET(0) |
               FDMA_CH_CFG_CH_MEM_SET(1),
               lan966x, FDMA_CH_CFG(fdma->channel_id));

        /* Start fdma */
        lan_rmw(FDMA_PORT_CTRL_XTR_STOP_SET(0),
                FDMA_PORT_CTRL_XTR_STOP,
                lan966x, FDMA_PORT_CTRL(0));

        /* Enable interrupts */
        mask = lan_rd(lan966x, FDMA_INTR_DB_ENA);
        mask = FDMA_INTR_DB_ENA_INTR_DB_ENA_GET(mask);
        mask |= BIT(fdma->channel_id);
        lan_rmw(FDMA_INTR_DB_ENA_INTR_DB_ENA_SET(mask),
                FDMA_INTR_DB_ENA_INTR_DB_ENA,
                lan966x, FDMA_INTR_DB_ENA);

        /* Activate the channel */
        lan_rmw(FDMA_CH_ACTIVATE_CH_ACTIVATE_SET(BIT(fdma->channel_id)),
                FDMA_CH_ACTIVATE_CH_ACTIVATE,
                lan966x, FDMA_CH_ACTIVATE);
}

static void lan966x_fdma_rx_disable(struct lan966x_rx *rx)
{
        struct lan966x *lan966x = rx->lan966x;
        struct fdma *fdma = &rx->fdma;
        u32 val;

        /* Disable the channel */
        lan_rmw(FDMA_CH_DISABLE_CH_DISABLE_SET(BIT(fdma->channel_id)),
                FDMA_CH_DISABLE_CH_DISABLE,
                lan966x, FDMA_CH_DISABLE);

        readx_poll_timeout_atomic(lan966x_fdma_channel_active, lan966x,
                                  val, !(val & BIT(fdma->channel_id)),
                                  READL_SLEEP_US, READL_TIMEOUT_US);

        lan_rmw(FDMA_CH_DB_DISCARD_DB_DISCARD_SET(BIT(fdma->channel_id)),
                FDMA_CH_DB_DISCARD_DB_DISCARD,
                lan966x, FDMA_CH_DB_DISCARD);
}

static void lan966x_fdma_rx_reload(struct lan966x_rx *rx)
{
        struct lan966x *lan966x = rx->lan966x;

        lan_rmw(FDMA_CH_RELOAD_CH_RELOAD_SET(BIT(rx->fdma.channel_id)),
                FDMA_CH_RELOAD_CH_RELOAD,
                lan966x, FDMA_CH_RELOAD);
}

static int lan966x_fdma_tx_alloc(struct lan966x_tx *tx)
{
        struct lan966x *lan966x = tx->lan966x;
        struct fdma *fdma = &tx->fdma;
        int err;

        tx->dcbs_buf = kzalloc_objs(struct lan966x_tx_dcb_buf, fdma->n_dcbs);
        if (!tx->dcbs_buf)
                return -ENOMEM;

        err = fdma_alloc_coherent(lan966x->dev, fdma);
        if (err)
                goto out;

        fdma_dcbs_init(fdma, 0, 0);

        return 0;

out:
        kfree(tx->dcbs_buf);
        return -ENOMEM;
}

static void lan966x_fdma_tx_free(struct lan966x_tx *tx)
{
        struct lan966x *lan966x = tx->lan966x;

        kfree(tx->dcbs_buf);
        fdma_free_coherent(lan966x->dev, &tx->fdma);
}

static void lan966x_fdma_tx_activate(struct lan966x_tx *tx)
{
        struct lan966x *lan966x = tx->lan966x;
        struct fdma *fdma = &tx->fdma;
        u32 mask;

        /* When activating a channel, first is required to write the first DCB
         * address and then to activate it
         */
        lan_wr(lower_32_bits((u64)fdma->dma), lan966x,
               FDMA_DCB_LLP(fdma->channel_id));
        lan_wr(upper_32_bits((u64)fdma->dma), lan966x,
               FDMA_DCB_LLP1(fdma->channel_id));

        lan_wr(FDMA_CH_CFG_CH_DCB_DB_CNT_SET(fdma->n_dbs) |
               FDMA_CH_CFG_CH_INTR_DB_EOF_ONLY_SET(1) |
               FDMA_CH_CFG_CH_INJ_PORT_SET(0) |
               FDMA_CH_CFG_CH_MEM_SET(1),
               lan966x, FDMA_CH_CFG(fdma->channel_id));

        /* Start fdma */
        lan_rmw(FDMA_PORT_CTRL_INJ_STOP_SET(0),
                FDMA_PORT_CTRL_INJ_STOP,
                lan966x, FDMA_PORT_CTRL(0));

        /* Enable interrupts */
        mask = lan_rd(lan966x, FDMA_INTR_DB_ENA);
        mask = FDMA_INTR_DB_ENA_INTR_DB_ENA_GET(mask);
        mask |= BIT(fdma->channel_id);
        lan_rmw(FDMA_INTR_DB_ENA_INTR_DB_ENA_SET(mask),
                FDMA_INTR_DB_ENA_INTR_DB_ENA,
                lan966x, FDMA_INTR_DB_ENA);

        /* Activate the channel */
        lan_rmw(FDMA_CH_ACTIVATE_CH_ACTIVATE_SET(BIT(fdma->channel_id)),
                FDMA_CH_ACTIVATE_CH_ACTIVATE,
                lan966x, FDMA_CH_ACTIVATE);
}

static void lan966x_fdma_tx_disable(struct lan966x_tx *tx)
{
        struct lan966x *lan966x = tx->lan966x;
        struct fdma *fdma = &tx->fdma;
        u32 val;

        /* Disable the channel */
        lan_rmw(FDMA_CH_DISABLE_CH_DISABLE_SET(BIT(fdma->channel_id)),
                FDMA_CH_DISABLE_CH_DISABLE,
                lan966x, FDMA_CH_DISABLE);

        readx_poll_timeout_atomic(lan966x_fdma_channel_active, lan966x,
                                  val, !(val & BIT(fdma->channel_id)),
                                  READL_SLEEP_US, READL_TIMEOUT_US);

        lan_rmw(FDMA_CH_DB_DISCARD_DB_DISCARD_SET(BIT(fdma->channel_id)),
                FDMA_CH_DB_DISCARD_DB_DISCARD,
                lan966x, FDMA_CH_DB_DISCARD);

        tx->activated = false;
}

static void lan966x_fdma_tx_reload(struct lan966x_tx *tx)
{
        struct lan966x *lan966x = tx->lan966x;

        /* Write the registers to reload the channel */
        lan_rmw(FDMA_CH_RELOAD_CH_RELOAD_SET(BIT(tx->fdma.channel_id)),
                FDMA_CH_RELOAD_CH_RELOAD,
                lan966x, FDMA_CH_RELOAD);
}

static void lan966x_fdma_wakeup_netdev(struct lan966x *lan966x)
{
        struct lan966x_port *port;
        int i;

        for (i = 0; i < lan966x->num_phys_ports; ++i) {
                port = lan966x->ports[i];
                if (!port)
                        continue;

                if (netif_queue_stopped(port->dev))
                        netif_wake_queue(port->dev);
        }
}

static void lan966x_fdma_stop_netdev(struct lan966x *lan966x)
{
        struct lan966x_port *port;
        int i;

        for (i = 0; i < lan966x->num_phys_ports; ++i) {
                port = lan966x->ports[i];
                if (!port)
                        continue;

                netif_stop_queue(port->dev);
        }
}

static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight)
{
        struct lan966x_tx *tx = &lan966x->tx;
        struct lan966x_rx *rx = &lan966x->rx;
        struct lan966x_tx_dcb_buf *dcb_buf;
        struct fdma *fdma = &tx->fdma;
        struct xdp_frame_bulk bq;
        unsigned long flags;
        bool clear = false;
        struct fdma_db *db;
        int i;

        xdp_frame_bulk_init(&bq);

        spin_lock_irqsave(&lan966x->tx_lock, flags);
        for (i = 0; i < fdma->n_dcbs; ++i) {
                dcb_buf = &tx->dcbs_buf[i];

                if (!dcb_buf->used)
                        continue;

                db = fdma_db_get(fdma, i, 0);
                if (!fdma_db_is_done(db))
                        continue;

                dcb_buf->dev->stats.tx_packets++;
                dcb_buf->dev->stats.tx_bytes += dcb_buf->len;

                dcb_buf->used = false;
                if (dcb_buf->use_skb) {
                        dma_unmap_single(lan966x->dev,
                                         dcb_buf->dma_addr,
                                         dcb_buf->len,
                                         DMA_TO_DEVICE);

                        if (!dcb_buf->ptp)
                                napi_consume_skb(dcb_buf->data.skb, weight);
                } else {
                        if (dcb_buf->xdp_ndo)
                                dma_unmap_single(lan966x->dev,
                                                 dcb_buf->dma_addr,
                                                 dcb_buf->len,
                                                 DMA_TO_DEVICE);

                        if (dcb_buf->xdp_ndo)
                                xdp_return_frame_bulk(dcb_buf->data.xdpf, &bq);
                        else
                                page_pool_recycle_direct(rx->page_pool,
                                                         dcb_buf->data.page);
                }

                clear = true;
        }

        xdp_flush_frame_bulk(&bq);

        if (clear)
                lan966x_fdma_wakeup_netdev(lan966x);

        spin_unlock_irqrestore(&lan966x->tx_lock, flags);
}

static int lan966x_fdma_rx_check_frame(struct lan966x_rx *rx, u64 *src_port)
{
        struct lan966x *lan966x = rx->lan966x;
        struct fdma *fdma = &rx->fdma;
        struct lan966x_port *port;
        struct fdma_db *db;
        struct page *page;

        db = fdma_db_next_get(fdma);
        page = rx->page[fdma->dcb_index][fdma->db_index];
        if (unlikely(!page))
                return FDMA_ERROR;

        dma_sync_single_for_cpu(lan966x->dev,
                                (dma_addr_t)db->dataptr + XDP_PACKET_HEADROOM,
                                FDMA_DCB_STATUS_BLOCKL(db->status),
                                DMA_FROM_DEVICE);

        lan966x_ifh_get_src_port(page_address(page) + XDP_PACKET_HEADROOM,
                                 src_port);
        if (WARN_ON(*src_port >= lan966x->num_phys_ports))
                return FDMA_ERROR;

        port = lan966x->ports[*src_port];
        if (!lan966x_xdp_port_present(port))
                return FDMA_PASS;

        return lan966x_xdp_run(port, page, FDMA_DCB_STATUS_BLOCKL(db->status));
}

static struct sk_buff *lan966x_fdma_rx_get_frame(struct lan966x_rx *rx,
                                                 u64 src_port)
{
        struct lan966x *lan966x = rx->lan966x;
        struct fdma *fdma = &rx->fdma;
        struct sk_buff *skb;
        struct fdma_db *db;
        struct page *page;
        u64 timestamp;

        /* Get the received frame and unmap it */
        db = fdma_db_next_get(fdma);
        page = rx->page[fdma->dcb_index][fdma->db_index];

        skb = build_skb(page_address(page), fdma->db_size);
        if (unlikely(!skb))
                goto free_page;

        skb_mark_for_recycle(skb);

        skb_reserve(skb, XDP_PACKET_HEADROOM);
        skb_put(skb, FDMA_DCB_STATUS_BLOCKL(db->status));

        lan966x_ifh_get_timestamp(skb->data, &timestamp);

        skb->dev = lan966x->ports[src_port]->dev;
        skb_pull(skb, IFH_LEN_BYTES);

        if (likely(!(skb->dev->features & NETIF_F_RXFCS)))
                skb_trim(skb, skb->len - ETH_FCS_LEN);

        lan966x_ptp_rxtstamp(lan966x, skb, src_port, timestamp);
        skb->protocol = eth_type_trans(skb, skb->dev);

        if (lan966x->bridge_mask & BIT(src_port)) {
                skb->offload_fwd_mark = 1;

                skb_reset_network_header(skb);
                if (!lan966x_hw_offload(lan966x, src_port, skb))
                        skb->offload_fwd_mark = 0;
        }

        skb->dev->stats.rx_bytes += skb->len;
        skb->dev->stats.rx_packets++;

        return skb;

free_page:
        page_pool_recycle_direct(rx->page_pool, page);

        return NULL;
}

static int lan966x_fdma_napi_poll(struct napi_struct *napi, int weight)
{
        struct lan966x *lan966x = container_of(napi, struct lan966x, napi);
        struct lan966x_rx *rx = &lan966x->rx;
        int old_dcb, dcb_reload, counter = 0;
        struct fdma *fdma = &rx->fdma;
        bool redirect = false;
        struct sk_buff *skb;
        u64 src_port;

        dcb_reload = fdma->dcb_index;

        lan966x_fdma_tx_clear_buf(lan966x, weight);

        /* Get all received skb */
        while (counter < weight) {
                if (!fdma_has_frames(fdma))
                        break;

                counter++;

                switch (lan966x_fdma_rx_check_frame(rx, &src_port)) {
                case FDMA_PASS:
                        break;
                case FDMA_ERROR:
                        lan966x_fdma_rx_free_page(rx);
                        fdma_dcb_advance(fdma);
                        goto allocate_new;
                case FDMA_REDIRECT:
                        redirect = true;
                        fallthrough;
                case FDMA_TX:
                        fdma_dcb_advance(fdma);
                        continue;
                case FDMA_DROP:
                        lan966x_fdma_rx_free_page(rx);
                        fdma_dcb_advance(fdma);
                        continue;
                }

                skb = lan966x_fdma_rx_get_frame(rx, src_port);
                fdma_dcb_advance(fdma);
                if (!skb)
                        goto allocate_new;

                napi_gro_receive(&lan966x->napi, skb);
        }

allocate_new:
        /* Allocate new pages and map them */
        while (dcb_reload != fdma->dcb_index) {
                old_dcb = dcb_reload;
                dcb_reload++;
                dcb_reload &= fdma->n_dcbs - 1;

                fdma_dcb_add(fdma, old_dcb, FDMA_DCB_INFO_DATAL(fdma->db_size),
                             FDMA_DCB_STATUS_INTR);

                lan966x_fdma_rx_reload(rx);
        }

        if (redirect)
                xdp_do_flush();

        if (counter < weight && napi_complete_done(napi, counter))
                lan_wr(0xff, lan966x, FDMA_INTR_DB_ENA);

        return counter;
}

irqreturn_t lan966x_fdma_irq_handler(int irq, void *args)
{
        struct lan966x *lan966x = args;
        u32 db, err, err_type;

        db = lan_rd(lan966x, FDMA_INTR_DB);
        err = lan_rd(lan966x, FDMA_INTR_ERR);

        if (db) {
                lan_wr(0, lan966x, FDMA_INTR_DB_ENA);
                lan_wr(db, lan966x, FDMA_INTR_DB);

                napi_schedule(&lan966x->napi);
        }

        if (err) {
                err_type = lan_rd(lan966x, FDMA_ERRORS);

                WARN(1, "Unexpected error: %d, error_type: %d\n", err, err_type);

                lan_wr(err, lan966x, FDMA_INTR_ERR);
                lan_wr(err_type, lan966x, FDMA_ERRORS);
        }

        return IRQ_HANDLED;
}

static int lan966x_fdma_get_next_dcb(struct lan966x_tx *tx)
{
        struct lan966x_tx_dcb_buf *dcb_buf;
        struct fdma *fdma = &tx->fdma;
        int i;

        for (i = 0; i < fdma->n_dcbs; ++i) {
                dcb_buf = &tx->dcbs_buf[i];
                if (!dcb_buf->used &&
                    !fdma_is_last(&tx->fdma, &tx->fdma.dcbs[i]))
                        return i;
        }

        return -1;
}

static void lan966x_fdma_tx_start(struct lan966x_tx *tx)
{
        struct lan966x *lan966x = tx->lan966x;

        if (likely(lan966x->tx.activated)) {
                lan966x_fdma_tx_reload(tx);
        } else {
                /* Because it is first time, then just activate */
                lan966x->tx.activated = true;
                lan966x_fdma_tx_activate(tx);
        }
}

int lan966x_fdma_xmit_xdpf(struct lan966x_port *port, void *ptr, u32 len)
{
        struct lan966x *lan966x = port->lan966x;
        struct lan966x_tx_dcb_buf *next_dcb_buf;
        struct lan966x_tx *tx = &lan966x->tx;
        struct xdp_frame *xdpf;
        dma_addr_t dma_addr;
        struct page *page;
        int next_to_use;
        __be32 *ifh;
        int ret = 0;

        spin_lock(&lan966x->tx_lock);

        /* Get next index */
        next_to_use = lan966x_fdma_get_next_dcb(tx);
        if (next_to_use < 0) {
                netif_stop_queue(port->dev);
                ret = NETDEV_TX_BUSY;
                goto out;
        }

        /* Get the next buffer */
        next_dcb_buf = &tx->dcbs_buf[next_to_use];

        /* Generate new IFH */
        if (!len) {
                xdpf = ptr;

                if (xdpf->headroom < IFH_LEN_BYTES) {
                        ret = NETDEV_TX_OK;
                        goto out;
                }

                ifh = xdpf->data - IFH_LEN_BYTES;
                memset(ifh, 0x0, sizeof(__be32) * IFH_LEN);
                lan966x_ifh_set_bypass(ifh, 1);
                lan966x_ifh_set_port(ifh, BIT_ULL(port->chip_port));

                dma_addr = dma_map_single(lan966x->dev,
                                          xdpf->data - IFH_LEN_BYTES,
                                          xdpf->len + IFH_LEN_BYTES,
                                          DMA_TO_DEVICE);
                if (dma_mapping_error(lan966x->dev, dma_addr)) {
                        ret = NETDEV_TX_OK;
                        goto out;
                }

                next_dcb_buf->data.xdpf = xdpf;
                next_dcb_buf->len = xdpf->len + IFH_LEN_BYTES;
        } else {
                page = ptr;

                ifh = page_address(page) + XDP_PACKET_HEADROOM;
                memset(ifh, 0x0, sizeof(__be32) * IFH_LEN);
                lan966x_ifh_set_bypass(ifh, 1);
                lan966x_ifh_set_port(ifh, BIT_ULL(port->chip_port));

                dma_addr = page_pool_get_dma_addr(page);
                dma_sync_single_for_device(lan966x->dev,
                                           dma_addr + XDP_PACKET_HEADROOM,
                                           len + IFH_LEN_BYTES,
                                           DMA_TO_DEVICE);

                next_dcb_buf->data.page = page;
                next_dcb_buf->len = len + IFH_LEN_BYTES;
        }

        /* Fill up the buffer */
        next_dcb_buf->use_skb = false;
        next_dcb_buf->xdp_ndo = !len;
        next_dcb_buf->dma_addr = dma_addr;
        next_dcb_buf->used = true;
        next_dcb_buf->ptp = false;
        next_dcb_buf->dev = port->dev;

        __fdma_dcb_add(&tx->fdma,
                       next_to_use,
                       0,
                       FDMA_DCB_STATUS_INTR |
                       FDMA_DCB_STATUS_SOF |
                       FDMA_DCB_STATUS_EOF |
                       FDMA_DCB_STATUS_BLOCKO(0) |
                       FDMA_DCB_STATUS_BLOCKL(next_dcb_buf->len),
                       &fdma_nextptr_cb,
                       &lan966x_fdma_xdp_tx_dataptr_cb);

        /* Start the transmission */
        lan966x_fdma_tx_start(tx);

out:
        spin_unlock(&lan966x->tx_lock);

        return ret;
}

int lan966x_fdma_xmit(struct sk_buff *skb, __be32 *ifh, struct net_device *dev)
{
        struct lan966x_port *port = netdev_priv(dev);
        struct lan966x *lan966x = port->lan966x;
        struct lan966x_tx_dcb_buf *next_dcb_buf;
        struct lan966x_tx *tx = &lan966x->tx;
        int needed_headroom;
        int needed_tailroom;
        dma_addr_t dma_addr;
        int next_to_use;
        int err;

        /* Get next index */
        next_to_use = lan966x_fdma_get_next_dcb(tx);
        if (next_to_use < 0) {
                netif_stop_queue(dev);
                return NETDEV_TX_BUSY;
        }

        if (skb_put_padto(skb, ETH_ZLEN)) {
                dev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        /* skb processing */
        needed_headroom = max_t(int, IFH_LEN_BYTES - skb_headroom(skb), 0);
        needed_tailroom = max_t(int, ETH_FCS_LEN - skb_tailroom(skb), 0);
        if (needed_headroom || needed_tailroom || skb_header_cloned(skb)) {
                err = pskb_expand_head(skb, needed_headroom, needed_tailroom,
                                       GFP_ATOMIC);
                if (unlikely(err)) {
                        dev->stats.tx_dropped++;
                        err = NETDEV_TX_OK;
                        goto release;
                }
        }

        skb_tx_timestamp(skb);
        skb_push(skb, IFH_LEN_BYTES);
        memcpy(skb->data, ifh, IFH_LEN_BYTES);
        skb_put(skb, 4);

        dma_addr = dma_map_single(lan966x->dev, skb->data, skb->len,
                                  DMA_TO_DEVICE);
        if (dma_mapping_error(lan966x->dev, dma_addr)) {
                dev->stats.tx_dropped++;
                err = NETDEV_TX_OK;
                goto release;
        }

        /* Fill up the buffer */
        next_dcb_buf = &tx->dcbs_buf[next_to_use];
        next_dcb_buf->use_skb = true;
        next_dcb_buf->data.skb = skb;
        next_dcb_buf->xdp_ndo = false;
        next_dcb_buf->len = skb->len;
        next_dcb_buf->dma_addr = dma_addr;
        next_dcb_buf->used = true;
        next_dcb_buf->ptp = false;
        next_dcb_buf->dev = dev;

        fdma_dcb_add(&tx->fdma,
                     next_to_use,
                     0,
                     FDMA_DCB_STATUS_INTR |
                     FDMA_DCB_STATUS_SOF |
                     FDMA_DCB_STATUS_EOF |
                     FDMA_DCB_STATUS_BLOCKO(0) |
                     FDMA_DCB_STATUS_BLOCKL(skb->len));

        if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
            LAN966X_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
                next_dcb_buf->ptp = true;

        /* Start the transmission */
        lan966x_fdma_tx_start(tx);

        return NETDEV_TX_OK;

release:
        if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP &&
            LAN966X_SKB_CB(skb)->rew_op == IFH_REW_OP_TWO_STEP_PTP)
                lan966x_ptp_txtstamp_release(port, skb);

        dev_kfree_skb_any(skb);
        return err;
}

static int lan966x_fdma_get_max_mtu(struct lan966x *lan966x)
{
        int max_mtu = 0;
        int i;

        for (i = 0; i < lan966x->num_phys_ports; ++i) {
                struct lan966x_port *port;
                int mtu;

                port = lan966x->ports[i];
                if (!port)
                        continue;

                mtu = lan_rd(lan966x, DEV_MAC_MAXLEN_CFG(port->chip_port));
                if (mtu > max_mtu)
                        max_mtu = mtu;
        }

        return max_mtu;
}

static int lan966x_qsys_sw_status(struct lan966x *lan966x)
{
        return lan_rd(lan966x, QSYS_SW_STATUS(CPU_PORT));
}

static int lan966x_fdma_reload(struct lan966x *lan966x, int new_mtu)
{
        struct page *(*old_pages)[FDMA_RX_DCB_MAX_DBS];
        struct page_pool *page_pool;
        struct fdma fdma_rx_old;
        int page_order, max_mtu;
        int err, i, j;

        old_pages = kmemdup(lan966x->rx.page, sizeof(lan966x->rx.page),
                           GFP_KERNEL);
        if (!old_pages)
                return -ENOMEM;

        /* Store these for later to free them */
        memcpy(&fdma_rx_old, &lan966x->rx.fdma, sizeof(struct fdma));
        page_pool = lan966x->rx.page_pool;
        page_order = lan966x->rx.page_order;
        max_mtu = lan966x->rx.max_mtu;

        napi_synchronize(&lan966x->napi);
        napi_disable(&lan966x->napi);
        lan966x_fdma_stop_netdev(lan966x);

        lan966x_fdma_rx_disable(&lan966x->rx);
        lan966x->rx.page_order = round_up(new_mtu, PAGE_SIZE) / PAGE_SIZE - 1;
        lan966x->rx.max_mtu = new_mtu;
        err = lan966x_fdma_rx_alloc(&lan966x->rx);
        if (err)
                goto restore;
        lan966x_fdma_rx_start(&lan966x->rx);

        for (i = 0; i < fdma_rx_old.n_dcbs; ++i)
                for (j = 0; j < fdma_rx_old.n_dbs; ++j)
                        page_pool_put_full_page(page_pool,
                                                old_pages[i][j], false);

        fdma_free_coherent(lan966x->dev, &fdma_rx_old);

        page_pool_destroy(page_pool);

        lan966x_fdma_wakeup_netdev(lan966x);
        napi_enable(&lan966x->napi);

        kfree(old_pages);
        return 0;
restore:
        lan966x->rx.page_pool = page_pool;
        lan966x->rx.page_order = page_order;
        lan966x->rx.max_mtu = max_mtu;
        memcpy(&lan966x->rx.fdma, &fdma_rx_old, sizeof(struct fdma));
        /*
         * lan966x_fdma_rx_alloc_page_pool() registered the new pool with
         * each port's XDP RXQ before the allocation failed. The new pool is
         * destroyed by lan966x_fdma_rx_alloc(), so restore the old pool's
         * registration before restarting RX.
         */
        for (i = 0; i < lan966x->num_phys_ports; i++) {
                if (!lan966x->ports[i])
                        continue;

                xdp_rxq_info_unreg_mem_model(&lan966x->ports[i]->xdp_rxq);
                xdp_rxq_info_reg_mem_model(&lan966x->ports[i]->xdp_rxq,
                                           MEM_TYPE_PAGE_POOL, page_pool);
        }

        lan966x_fdma_rx_start(&lan966x->rx);

        lan966x_fdma_wakeup_netdev(lan966x);
        napi_enable(&lan966x->napi);

        kfree(old_pages);
        return err;
}

static int lan966x_fdma_get_max_frame(struct lan966x *lan966x)
{
        return lan966x_fdma_get_max_mtu(lan966x) +
               IFH_LEN_BYTES +
               SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) +
               VLAN_HLEN * 2 +
               XDP_PACKET_HEADROOM;
}

static int __lan966x_fdma_reload(struct lan966x *lan966x, int max_mtu)
{
        int err;
        u32 val;

        /* Disable the CPU port */
        lan_rmw(QSYS_SW_PORT_MODE_PORT_ENA_SET(0),
                QSYS_SW_PORT_MODE_PORT_ENA,
                lan966x, QSYS_SW_PORT_MODE(CPU_PORT));

        /* Flush the CPU queues */
        readx_poll_timeout(lan966x_qsys_sw_status, lan966x,
                           val, !(QSYS_SW_STATUS_EQ_AVAIL_GET(val)),
                           READL_SLEEP_US, READL_TIMEOUT_US);

        /* Add a sleep in case there are frames between the queues and the CPU
         * port
         */
        usleep_range(1000, 2000);

        err = lan966x_fdma_reload(lan966x, max_mtu);

        /* Enable back the CPU port */
        lan_rmw(QSYS_SW_PORT_MODE_PORT_ENA_SET(1),
                QSYS_SW_PORT_MODE_PORT_ENA,
                lan966x,  QSYS_SW_PORT_MODE(CPU_PORT));

        return err;
}

int lan966x_fdma_change_mtu(struct lan966x *lan966x)
{
        int max_mtu;

        max_mtu = lan966x_fdma_get_max_frame(lan966x);
        if (max_mtu == lan966x->rx.max_mtu)
                return 0;

        return __lan966x_fdma_reload(lan966x, max_mtu);
}

int lan966x_fdma_reload_page_pool(struct lan966x *lan966x)
{
        int max_mtu;

        max_mtu = lan966x_fdma_get_max_frame(lan966x);
        return __lan966x_fdma_reload(lan966x, max_mtu);
}

void lan966x_fdma_netdev_init(struct lan966x *lan966x, struct net_device *dev)
{
        if (lan966x->fdma_ndev)
                return;

        lan966x->fdma_ndev = dev;
        netif_napi_add(dev, &lan966x->napi, lan966x_fdma_napi_poll);
        napi_enable(&lan966x->napi);
}

void lan966x_fdma_netdev_deinit(struct lan966x *lan966x, struct net_device *dev)
{
        if (lan966x->fdma_ndev == dev) {
                netif_napi_del(&lan966x->napi);
                lan966x->fdma_ndev = NULL;
        }
}

int lan966x_fdma_init(struct lan966x *lan966x)
{
        int err;

        if (!lan966x->fdma)
                return 0;

        lan966x->rx.lan966x = lan966x;
        lan966x->rx.fdma.channel_id = FDMA_XTR_CHANNEL;
        lan966x->rx.fdma.n_dcbs = FDMA_DCB_MAX;
        lan966x->rx.fdma.n_dbs = FDMA_RX_DCB_MAX_DBS;
        lan966x->rx.fdma.priv = lan966x;
        lan966x->rx.fdma.size = fdma_get_size(&lan966x->rx.fdma);
        lan966x->rx.fdma.db_size = PAGE_SIZE << lan966x->rx.page_order;
        lan966x->rx.fdma.ops.nextptr_cb = &fdma_nextptr_cb;
        lan966x->rx.fdma.ops.dataptr_cb = &lan966x_fdma_rx_dataptr_cb;
        lan966x->rx.max_mtu = lan966x_fdma_get_max_frame(lan966x);
        lan966x->tx.lan966x = lan966x;
        lan966x->tx.fdma.channel_id = FDMA_INJ_CHANNEL;
        lan966x->tx.fdma.n_dcbs = FDMA_DCB_MAX;
        lan966x->tx.fdma.n_dbs = FDMA_TX_DCB_MAX_DBS;
        lan966x->tx.fdma.priv = lan966x;
        lan966x->tx.fdma.size = fdma_get_size(&lan966x->tx.fdma);
        lan966x->tx.fdma.db_size = PAGE_SIZE << lan966x->rx.page_order;
        lan966x->tx.fdma.ops.nextptr_cb = &fdma_nextptr_cb;
        lan966x->tx.fdma.ops.dataptr_cb = &lan966x_fdma_tx_dataptr_cb;

        err = lan966x_fdma_rx_alloc(&lan966x->rx);
        if (err)
                return err;

        err = lan966x_fdma_tx_alloc(&lan966x->tx);
        if (err) {
                fdma_free_coherent(lan966x->dev, &lan966x->rx.fdma);
                page_pool_destroy(lan966x->rx.page_pool);
                return err;
        }

        lan966x_fdma_rx_start(&lan966x->rx);

        return 0;
}

void lan966x_fdma_deinit(struct lan966x *lan966x)
{
        if (!lan966x->fdma)
                return;

        lan966x_fdma_rx_disable(&lan966x->rx);
        lan966x_fdma_tx_disable(&lan966x->tx);

        napi_synchronize(&lan966x->napi);
        napi_disable(&lan966x->napi);

        lan966x_fdma_rx_free_pages(&lan966x->rx);
        fdma_free_coherent(lan966x->dev, &lan966x->rx.fdma);
        page_pool_destroy(lan966x->rx.page_pool);
        lan966x_fdma_tx_free(&lan966x->tx);
}