// SPDX-License-Identifier: GPL-2.0

  #include <linux/export.h>

  #include <linux/if_vlan.h>

  #include <net/ip.h>
  #include <net/tso.h>

  #include <asm/unaligned.h>

  
  /* Calculate expected number of TX descriptors */
  int tso_count_descs(struct sk_buff *skb)
  {
  	/* The Marvell Way */
  	return skb_shinfo(skb)->gso_segs * 2 + skb_shinfo(skb)->nr_frags;
  }

  EXPORT_SYMBOL(tso_count_descs);

  
  void tso_build_hdr(struct sk_buff *skb, char *hdr, struct tso_t *tso,
  		   int size, bool is_last)
  {

  	struct tcphdr *tcph;
  	int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
  	int mac_hdr_len = skb_network_offset(skb);
  
  	memcpy(hdr, skb->data, hdr_len);

  	if (!tso->ipv6) {
  		struct iphdr *iph = (void *)(hdr + mac_hdr_len);
  
  		iph->id = htons(tso->ip_id);
  		iph->tot_len = htons(size + hdr_len - mac_hdr_len);
  		tso->ip_id++;
  	} else {
  		struct ipv6hdr *iph = (void *)(hdr + mac_hdr_len);
  
  		iph->payload_len = htons(size + tcp_hdrlen(skb));
  	}

  	tcph = (struct tcphdr *)(hdr + skb_transport_offset(skb));

  	put_unaligned_be32(tso->tcp_seq, &tcph->seq);

  
  	if (!is_last) {
  		/* Clear all special flags for not last packet */
  		tcph->psh = 0;
  		tcph->fin = 0;
  		tcph->rst = 0;
  	}
  }

  EXPORT_SYMBOL(tso_build_hdr);

  
  void tso_build_data(struct sk_buff *skb, struct tso_t *tso, int size)
  {
  	tso->tcp_seq += size;
  	tso->size -= size;
  	tso->data += size;
  
  	if ((tso->size == 0) &&
  	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
  		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
  
  		/* Move to next segment */
  		tso->size = frag->size;
  		tso->data = page_address(frag->page.p) + frag->page_offset;
  		tso->next_frag_idx++;
  	}
  }

  EXPORT_SYMBOL(tso_build_data);

  
  void tso_start(struct sk_buff *skb, struct tso_t *tso)
  {
  	int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
  
  	tso->ip_id = ntohs(ip_hdr(skb)->id);
  	tso->tcp_seq = ntohl(tcp_hdr(skb)->seq);
  	tso->next_frag_idx = 0;

  	tso->ipv6 = vlan_get_protocol(skb) == htons(ETH_P_IPV6);

  
  	/* Build first data */
  	tso->size = skb_headlen(skb) - hdr_len;
  	tso->data = skb->data + hdr_len;
  	if ((tso->size == 0) &&
  	    (tso->next_frag_idx < skb_shinfo(skb)->nr_frags)) {
  		skb_frag_t *frag = &skb_shinfo(skb)->frags[tso->next_frag_idx];
  
  		/* Move to next segment */
  		tso->size = frag->size;
  		tso->data = page_address(frag->page.p) + frag->page_offset;
  		tso->next_frag_idx++;
  	}
  }

  EXPORT_SYMBOL(tso_start);