// SPDX-License-Identifier: GPL-2.0-or-later
/* Broadcom NetXtreme-C/E network driver.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.
 */

#include <linux/pci.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/netdev_queues.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/udp.h>
#include <net/tso.h>
#include <linux/bnxt/hsi.h>

#include "bnxt.h"
#include "bnxt_gso.h"

static u32 bnxt_sw_gso_lhint(unsigned int len)
{
        if (len <= 512)
                return TX_BD_FLAGS_LHINT_512_AND_SMALLER;
        else if (len <= 1023)
                return TX_BD_FLAGS_LHINT_512_TO_1023;
        else if (len <= 2047)
                return TX_BD_FLAGS_LHINT_1024_TO_2047;
        else
                return TX_BD_FLAGS_LHINT_2048_AND_LARGER;
}

netdev_tx_t bnxt_sw_udp_gso_xmit(struct bnxt *bp,
                                 struct bnxt_tx_ring_info *txr,
                                 struct netdev_queue *txq,
                                 struct sk_buff *skb)
{
        unsigned int last_unmap_len __maybe_unused = 0;
        dma_addr_t last_unmap_addr __maybe_unused = 0;
        struct bnxt_sw_tx_bd *last_unmap_buf = NULL;
        unsigned int hdr_len, mss, num_segs;
        struct pci_dev *pdev = bp->pdev;
        unsigned int total_payload;
        struct tso_dma_map map;
        u32 vlan_tag_flags = 0;
        int i, bds_needed;
        struct tso_t tso;
        u16 cfa_action;
        __le32 csum;
        u16 prod;

        hdr_len = tso_start(skb, &tso);
        mss = skb_shinfo(skb)->gso_size;
        total_payload = skb->len - hdr_len;
        num_segs = DIV_ROUND_UP(total_payload, mss);

        if (unlikely(num_segs <= 1))
                goto drop;

        /* Upper bound on the number of descriptors needed.
         *
         * Each segment uses 1 long BD + 1 ext BD + payload BDs, which is
         * at most num_segs + nr_frags (each frag boundary crossing adds at
         * most 1 extra BD).
         */
        bds_needed = 3 * num_segs + skb_shinfo(skb)->nr_frags + 1;

        if (unlikely(bnxt_tx_avail(bp, txr) < bds_needed)) {
                netif_txq_try_stop(txq, bnxt_tx_avail(bp, txr),
                                   bp->tx_wake_thresh);
                return NETDEV_TX_BUSY;
        }

        /* BD backpressure alone cannot prevent overwriting in-flight
         * headers in the inline buffer. Check slot availability directly.
         */
        if (!netif_txq_maybe_stop(txq, bnxt_inline_avail(txr),
                                  num_segs, num_segs))
                return NETDEV_TX_BUSY;

        if (unlikely(tso_dma_map_init(&map, &pdev->dev, skb, hdr_len)))
                goto drop;

        cfa_action = bnxt_xmit_get_cfa_action(skb);
        if (skb_vlan_tag_present(skb)) {
                vlan_tag_flags = TX_BD_CFA_META_KEY_VLAN |
                                 skb_vlan_tag_get(skb);
                if (skb->vlan_proto == htons(ETH_P_8021Q))
                        vlan_tag_flags |= 1 << TX_BD_CFA_META_TPID_SHIFT;
        }

        csum = cpu_to_le32(TX_BD_FLAGS_TCP_UDP_CHKSUM);
        if (!tso.ipv6)
                csum |= cpu_to_le32(TX_BD_FLAGS_IP_CKSUM);

        prod = txr->tx_prod;

        for (i = 0; i < num_segs; i++) {
                unsigned int seg_payload = min_t(unsigned int, mss,
                                                 total_payload - i * mss);
                u16 slot = (txr->tx_inline_prod + i) &
                           (BNXT_SW_USO_MAX_SEGS - 1);
                struct bnxt_sw_tx_bd *tx_buf;
                unsigned int mapping_len;
                dma_addr_t this_hdr_dma;
                unsigned int chunk_len;
                unsigned int offset;
                dma_addr_t dma_addr;
                struct tx_bd *txbd;
                struct udphdr *uh;
                void *this_hdr;
                int bd_count;
                bool last;
                u32 flags;

                last = (i == num_segs - 1);
                offset = slot * TSO_HEADER_SIZE;
                this_hdr = txr->tx_inline_buf + offset;
                this_hdr_dma = txr->tx_inline_dma + offset;

                tso_build_hdr(skb, this_hdr, &tso, seg_payload, last);

                /* Zero stale csum fields copied from the original skb;
                 * HW offload recomputes from scratch.
                 */
                uh = this_hdr + skb_transport_offset(skb);
                uh->check = 0;
                if (!tso.ipv6) {
                        struct iphdr *iph = this_hdr + skb_network_offset(skb);

                        iph->check = 0;
                }

                dma_sync_single_for_device(&pdev->dev, this_hdr_dma,
                                           hdr_len, DMA_TO_DEVICE);

                bd_count = tso_dma_map_count(&map, seg_payload);

                tx_buf = &txr->tx_buf_ring[RING_TX(bp, prod)];
                txbd = &txr->tx_desc_ring[TX_RING(bp, prod)][TX_IDX(prod)];

                tx_buf->skb = skb;
                tx_buf->nr_frags = bd_count;
                tx_buf->is_push = 0;
                tx_buf->is_ts_pkt = 0;

                dma_unmap_addr_set(tx_buf, mapping, this_hdr_dma);
                dma_unmap_len_set(tx_buf, len, 0);

                if (last) {
                        tx_buf->is_sw_gso = BNXT_SW_GSO_LAST;
                        tso_dma_map_completion_save(&map, &tx_buf->sw_gso_cstate);
                } else {
                        tx_buf->is_sw_gso = BNXT_SW_GSO_MID;
                }

                flags = (hdr_len << TX_BD_LEN_SHIFT) |
                        TX_BD_TYPE_LONG_TX_BD |
                        TX_BD_CNT(2 + bd_count);

                flags |= bnxt_sw_gso_lhint(hdr_len + seg_payload);

                txbd->tx_bd_len_flags_type = cpu_to_le32(flags);
                txbd->tx_bd_haddr = cpu_to_le64(this_hdr_dma);
                txbd->tx_bd_opaque = SET_TX_OPAQUE(bp, txr, prod,
                                                   2 + bd_count);

                prod = NEXT_TX(prod);
                bnxt_init_ext_bd(bp, txr, prod, csum,
                                 vlan_tag_flags, cfa_action);

                /* set dma_unmap_len on the LAST BD touching each
                 * region. Since completions are in-order, the last segment
                 * completes after all earlier ones, so the unmap is safe.
                 */
                while (tso_dma_map_next(&map, &dma_addr, &chunk_len,
                                        &mapping_len, seg_payload)) {
                        prod = NEXT_TX(prod);
                        txbd = &txr->tx_desc_ring[TX_RING(bp, prod)][TX_IDX(prod)];
                        tx_buf = &txr->tx_buf_ring[RING_TX(bp, prod)];

                        txbd->tx_bd_haddr = cpu_to_le64(dma_addr);
                        dma_unmap_addr_set(tx_buf, mapping, dma_addr);
                        dma_unmap_len_set(tx_buf, len, 0);
                        tx_buf->skb = NULL;
                        tx_buf->is_sw_gso = 0;

                        if (mapping_len) {
                                if (last_unmap_buf) {
                                        dma_unmap_addr_set(last_unmap_buf,
                                                           mapping,
                                                           last_unmap_addr);
                                        dma_unmap_len_set(last_unmap_buf,
                                                          len,
                                                          last_unmap_len);
                                }
                                last_unmap_addr = dma_addr;
                                last_unmap_len = mapping_len;
                        }
                        last_unmap_buf = tx_buf;

                        flags = chunk_len << TX_BD_LEN_SHIFT;
                        txbd->tx_bd_len_flags_type = cpu_to_le32(flags);
                        txbd->tx_bd_opaque = 0;

                        seg_payload -= chunk_len;
                }

                txbd->tx_bd_len_flags_type |=
                        cpu_to_le32(TX_BD_FLAGS_PACKET_END);

                prod = NEXT_TX(prod);
        }

        if (last_unmap_buf) {
                dma_unmap_addr_set(last_unmap_buf, mapping, last_unmap_addr);
                dma_unmap_len_set(last_unmap_buf, len, last_unmap_len);
        }

        txr->tx_inline_prod += num_segs;

        netdev_tx_sent_queue(txq, skb->len);

        WRITE_ONCE(txr->tx_prod, prod);
        /* Sync BDs before doorbell */
        wmb();
        bnxt_db_write(bp, &txr->tx_db, prod);

        if (unlikely(bnxt_tx_avail(bp, txr) <= bp->tx_wake_thresh))
                netif_txq_try_stop(txq, bnxt_tx_avail(bp, txr),
                                   bp->tx_wake_thresh);

        return NETDEV_TX_OK;

drop:
        dev_kfree_skb_any(skb);
        dev_core_stats_tx_dropped_inc(bp->dev);
        return NETDEV_TX_OK;
}