drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c

// 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);

	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 PTR_ERR_OR_ZERO(rx->page_pool);
}

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

	if (lan966x_fdma_rx_alloc_page_pool(rx))
		return PTR_ERR(rx->page_pool);

	err = fdma_alloc_coherent(lan966x->dev, fdma);
	if (err)
		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 = kcalloc(fdma->n_dcbs, sizeof(struct lan966x_tx_dcb_buf),
			       GFP_KERNEL);
	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_pool *page_pool;
	struct fdma fdma_rx_old;
	int err;

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

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

	lan966x_fdma_rx_disable(&lan966x->rx);
	lan966x_fdma_rx_free_pages(&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);

	fdma_free_coherent(lan966x->dev, &fdma_rx_old);

	page_pool_destroy(page_pool);

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

	return err;
restore:
	lan966x->rx.page_pool = page_pool;
	memcpy(&lan966x->rx.fdma, &fdma_rx_old, sizeof(struct fdma));
	lan966x_fdma_rx_start(&lan966x->rx);

	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);
		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);
}