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// SPDX-License-Identifier: (GPL-2.0 OR MIT)
/*
* net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling
*
* Copyright (C) 2019,2020 Linutronix GmbH
* Author Kurt Kanzenbach <kurt@linutronix.de>
*
* Based on tag_ksz.c.
*/
#include <linux/skbuff.h>
#include <net/dsa.h>
#include "dsa_priv.h"
#define HELLCREEK_TAG_LEN 1
static struct sk_buff *hellcreek_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
u8 *tag;
/* Calculate checksums (if required) before adding the trailer tag to
* avoid including it in calculations. That would lead to wrong
* checksums after the switch strips the tag.
*/
if (skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_help(skb))
return NULL;
/* Tag encoding */
tag = skb_put(skb, HELLCREEK_TAG_LEN);
*tag = BIT(dp->index);
return skb;
}
static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
struct net_device *dev)
{
/* Tag decoding */
u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
unsigned int port = tag[0] & 0x03;
skb->dev = dsa_master_find_slave(dev, 0, port);
if (!skb->dev) {
netdev_warn(dev, "Failed to get source port: %d\n", port);
return NULL;
}
pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN);
dsa_default_offload_fwd_mark(skb);
return skb;
}
static const struct dsa_device_ops hellcreek_netdev_ops = {
.name = "hellcreek",
.proto = DSA_TAG_PROTO_HELLCREEK,
.xmit = hellcreek_xmit,
.rcv = hellcreek_rcv,
.needed_tailroom = HELLCREEK_TAG_LEN,
};
MODULE_LICENSE("Dual MIT/GPL");
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK);
module_dsa_tag_driver(hellcreek_netdev_ops);
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