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// SPDX-License-Identifier: GPL-2.0+
/*
* net/dsa/tag_dsa.c - (Non-ethertype) DSA tagging
* Copyright (c) 2008-2009 Marvell Semiconductor
*/
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>
#include "dsa_priv.h"
#define DSA_HLEN 4
static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
u8 *dsa_header;
/*
* Convert the outermost 802.1q tag to a DSA tag for tagged
* packets, or insert a DSA tag between the addresses and
* the ethertype field for untagged packets.
*/
if (skb->protocol == htons(ETH_P_8021Q)) {
if (skb_cow_head(skb, 0) < 0)
return NULL;
/*
* Construct tagged FROM_CPU DSA tag from 802.1q tag.
*/
dsa_header = skb->data + 2 * ETH_ALEN;
dsa_header[0] = 0x60 | dp->ds->index;
dsa_header[1] = dp->index << 3;
/*
* Move CFI field from byte 2 to byte 1.
*/
if (dsa_header[2] & 0x10) {
dsa_header[1] |= 0x01;
dsa_header[2] &= ~0x10;
}
} else {
if (skb_cow_head(skb, DSA_HLEN) < 0)
return NULL;
skb_push(skb, DSA_HLEN);
memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
/*
* Construct untagged FROM_CPU DSA tag.
*/
dsa_header = skb->data + 2 * ETH_ALEN;
dsa_header[0] = 0x40 | dp->ds->index;
dsa_header[1] = dp->index << 3;
dsa_header[2] = 0x00;
dsa_header[3] = 0x00;
}
return skb;
}
static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt)
{
u8 *dsa_header;
int source_device;
int source_port;
if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
return NULL;
/*
* The ethertype field is part of the DSA header.
*/
dsa_header = skb->data - 2;
/*
* Check that frame type is either TO_CPU or FORWARD.
*/
if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
return NULL;
/*
* Determine source device and port.
*/
source_device = dsa_header[0] & 0x1f;
source_port = (dsa_header[1] >> 3) & 0x1f;
skb->dev = dsa_master_find_slave(dev, source_device, source_port);
if (!skb->dev)
return NULL;
/*
* Convert the DSA header to an 802.1q header if the 'tagged'
* bit in the DSA header is set. If the 'tagged' bit is clear,
* delete the DSA header entirely.
*/
if (dsa_header[0] & 0x20) {
u8 new_header[4];
/*
* Insert 802.1q ethertype and copy the VLAN-related
* fields, but clear the bit that will hold CFI (since
* DSA uses that bit location for another purpose).
*/
new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
new_header[1] = ETH_P_8021Q & 0xff;
new_header[2] = dsa_header[2] & ~0x10;
new_header[3] = dsa_header[3];
/*
* Move CFI bit from its place in the DSA header to
* its 802.1q-designated place.
*/
if (dsa_header[1] & 0x01)
new_header[2] |= 0x10;
/*
* Update packet checksum if skb is CHECKSUM_COMPLETE.
*/
if (skb->ip_summed == CHECKSUM_COMPLETE) {
__wsum c = skb->csum;
c = csum_add(c, csum_partial(new_header + 2, 2, 0));
c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
skb->csum = c;
}
memcpy(dsa_header, new_header, DSA_HLEN);
} else {
/*
* Remove DSA tag and update checksum.
*/
skb_pull_rcsum(skb, DSA_HLEN);
memmove(skb->data - ETH_HLEN,
skb->data - ETH_HLEN - DSA_HLEN,
2 * ETH_ALEN);
}
skb->offload_fwd_mark = 1;
return skb;
}
static const struct dsa_device_ops dsa_netdev_ops = {
.name = "dsa",
.proto = DSA_TAG_PROTO_DSA,
.xmit = dsa_xmit,
.rcv = dsa_rcv,
.overhead = DSA_HLEN,
};
MODULE_LICENSE("GPL");
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA);
module_dsa_tag_driver(dsa_netdev_ops);
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