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/*
* net/dsa/tag_ksz.c - Microchip KSZ Switch tag format handling
* Copyright (c) 2017 Microchip Technology
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <net/dsa.h>
#include "dsa_priv.h"
/* For Ingress (Host -> KSZ), 2 bytes are added before FCS.
* ---------------------------------------------------------------------------
* DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|tag1(1byte)|FCS(4bytes)
* ---------------------------------------------------------------------------
* tag0 : Prioritization (not used now)
* tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
*
* For Egress (KSZ -> Host), 1 byte is added before FCS.
* ---------------------------------------------------------------------------
* DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
* ---------------------------------------------------------------------------
* tag0 : zero-based value represents port
* (eg, 0x00=port1, 0x02=port3, 0x06=port7)
*/
#define KSZ_INGRESS_TAG_LEN 2
#define KSZ_EGRESS_TAG_LEN 1
static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
struct sk_buff *nskb;
int padlen;
u8 *tag;
padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
if (skb_tailroom(skb) >= padlen + KSZ_INGRESS_TAG_LEN) {
/* Let dsa_slave_xmit() free skb */
if (__skb_put_padto(skb, skb->len + padlen, false))
return NULL;
nskb = skb;
} else {
nskb = alloc_skb(NET_IP_ALIGN + skb->len +
padlen + KSZ_INGRESS_TAG_LEN, GFP_ATOMIC);
if (!nskb)
return NULL;
skb_reserve(nskb, NET_IP_ALIGN);
skb_reset_mac_header(nskb);
skb_set_network_header(nskb,
skb_network_header(skb) - skb->head);
skb_set_transport_header(nskb,
skb_transport_header(skb) - skb->head);
skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
/* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free
* skb
*/
if (skb_put_padto(nskb, nskb->len + padlen))
return NULL;
consume_skb(skb);
}
tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
tag[0] = 0;
tag[1] = 1 << dp->index; /* destination port */
return nskb;
}
static struct sk_buff *ksz_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt)
{
u8 *tag;
int source_port;
tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;
source_port = tag[0] & 7;
skb->dev = dsa_master_find_slave(dev, 0, source_port);
if (!skb->dev)
return NULL;
pskb_trim_rcsum(skb, skb->len - KSZ_EGRESS_TAG_LEN);
return skb;
}
const struct dsa_device_ops ksz_netdev_ops = {
.xmit = ksz_xmit,
.rcv = ksz_rcv,
};
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