net/dsa/tag_hellcreek.c

   1 // SPDX-License-Identifier: (GPL-2.0 OR MIT)
   2 /*
   3  * net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling
   4  *
   5  * Copyright (C) 2019,2020 Linutronix GmbH
   6  * Author Kurt Kanzenbach <[email protected]>
   7  *
   8  * Based on tag_ksz.c.
   9  */
  10
  11 #include <linux/skbuff.h>
  12 #include <net/dsa.h>
  13
  14 #include "dsa_priv.h"
  15
  16 #define HELLCREEK_TAG_LEN       1
  17
  18 static struct sk_buff *hellcreek_xmit(struct sk_buff *skb,
  19                                       struct net_device *dev)
  20 {
  21         struct dsa_port *dp = dsa_slave_to_port(dev);
  22         u8 *tag;
  23
  24         /* Tag encoding */
  25         tag  = skb_put(skb, HELLCREEK_TAG_LEN);
  26         *tag = BIT(dp->index);
  27
  28         return skb;
  29 }
  30
  31 static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
  32                                      struct net_device *dev,
  33                                      struct packet_type *pt)
  34 {
  35         /* Tag decoding */
  36         u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
  37         unsigned int port = tag[0] & 0x03;
  38
  39         skb->dev = dsa_master_find_slave(dev, 0, port);
  40         if (!skb->dev) {
  41                 netdev_warn(dev, "Failed to get source port: %d\n", port);
  42                 return NULL;
  43         }
  44
  45         pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN);
  46
  47         skb->offload_fwd_mark = true;
  48
  49         return skb;
  50 }
  51
  52 static const struct dsa_device_ops hellcreek_netdev_ops = {
  53         .name     = "hellcreek",
  54         .proto    = DSA_TAG_PROTO_HELLCREEK,
  55         .xmit     = hellcreek_xmit,
  56         .rcv      = hellcreek_rcv,
  57         .overhead = HELLCREEK_TAG_LEN,
  58         .tail_tag = true,
  59 };
  60
  61 MODULE_LICENSE("Dual MIT/GPL");
  62 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK);
  63
  64 module_dsa_tag_driver(hellcreek_netdev_ops);