net/dsa/tag_xrs700x.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * XRS700x tag format handling
   4  * Copyright (c) 2008-2009 Marvell Semiconductor
   5  * Copyright (c) 2020 NovaTech LLC
   6  */
   7
   8 #include <linux/bitops.h>
   9
  10 #include "dsa_priv.h"
  11
  12 static struct sk_buff *xrs700x_xmit(struct sk_buff *skb, struct net_device *dev)
  13 {
  14         struct dsa_port *partner, *dp = dsa_slave_to_port(dev);
  15         u8 *trailer;
  16
  17         trailer = skb_put(skb, 1);
  18         trailer[0] = BIT(dp->index);
  19
  20         if (dp->hsr_dev)
  21                 dsa_hsr_foreach_port(partner, dp->ds, dp->hsr_dev)
  22                         if (partner != dp)
  23                                 trailer[0] |= BIT(partner->index);
  24
  25         return skb;
  26 }
  27
  28 static struct sk_buff *xrs700x_rcv(struct sk_buff *skb, struct net_device *dev)
  29 {
  30         int source_port;
  31         u8 *trailer;
  32
  33         trailer = skb_tail_pointer(skb) - 1;
  34
  35         source_port = ffs((int)trailer[0]) - 1;
  36
  37         if (source_port < 0)
  38                 return NULL;
  39
  40         skb->dev = dsa_master_find_slave(dev, 0, source_port);
  41         if (!skb->dev)
  42                 return NULL;
  43
  44         if (pskb_trim_rcsum(skb, skb->len - 1))
  45                 return NULL;
  46
  47         /* Frame is forwarded by hardware, don't forward in software. */
  48         dsa_default_offload_fwd_mark(skb);
  49
  50         return skb;
  51 }
  52
  53 static const struct dsa_device_ops xrs700x_netdev_ops = {
  54         .name   = "xrs700x",
  55         .proto  = DSA_TAG_PROTO_XRS700X,
  56         .xmit   = xrs700x_xmit,
  57         .rcv    = xrs700x_rcv,
  58         .needed_tailroom = 1,
  59 };
  60
  61 MODULE_LICENSE("GPL");
  62 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_XRS700X);
  63
  64 module_dsa_tag_driver(xrs700x_netdev_ops);