tag_lan9303.c
3.79 KB
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/*
* Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>
#include "dsa_priv.h"
/* To define the outgoing port and to discover the incoming port a regular
* VLAN tag is used by the LAN9303. But its VID meaning is 'special':
*
* Dest MAC Src MAC TAG Type
* ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 | 1 2 |...
* |<------->|
* TAG:
* |<------------->|
* | 1 2 | 3 4 |
* TPID VID
* 0x8100
*
* VID bit 3 indicates a request for an ALR lookup.
*
* If VID bit 3 is zero, then bits 0 and 1 specify the destination port
* (0, 1, 2) or broadcast (3) or the source port (1, 2).
*
* VID bit 4 is used to specify if the STP port state should be overridden.
* Required when no forwarding between the external ports should happen.
*/
#define LAN9303_TAG_LEN 4
static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_slave_priv *p = netdev_priv(dev);
u16 *lan9303_tag;
/* insert a special VLAN tag between the MAC addresses
* and the current ethertype field.
*/
if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) {
dev_dbg(&dev->dev,
"Cannot make room for the special tag. Dropping packet\n");
return NULL;
}
/* provide 'LAN9303_TAG_LEN' bytes additional space */
skb_push(skb, LAN9303_TAG_LEN);
/* make room between MACs and Ether-Type */
memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN);
lan9303_tag = (u16 *)(skb->data + 2 * ETH_ALEN);
lan9303_tag[0] = htons(ETH_P_8021Q);
lan9303_tag[1] = htons(p->dp->index | BIT(4));
return skb;
}
static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt)
{
u16 *lan9303_tag;
struct dsa_switch_tree *dst = dev->dsa_ptr;
struct dsa_switch *ds;
unsigned int source_port;
ds = dst->ds[0];
if (unlikely(!ds)) {
dev_warn_ratelimited(&dev->dev, "Dropping packet, due to missing DSA switch device\n");
return NULL;
}
if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
dev_warn_ratelimited(&dev->dev,
"Dropping packet, cannot pull\n");
return NULL;
}
/* '->data' points into the middle of our special VLAN tag information:
*
* ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type
* ^
* ->data
*/
lan9303_tag = (u16 *)(skb->data - 2);
if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
return NULL;
}
source_port = ntohs(lan9303_tag[1]) & 0x3;
if (source_port >= ds->num_ports) {
dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
return NULL;
}
if (unlikely(ds->cpu_port_mask & BIT(source_port)))
return NULL;
if (!ds->ports[source_port].netdev) {
dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid netdev or device\n");
return NULL;
}
/* remove the special VLAN tag between the MAC addresses
* and the current ethertype field.
*/
skb_pull_rcsum(skb, 2 + 2);
memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
2 * ETH_ALEN);
/* forward the packet to the dedicated interface */
skb->dev = ds->ports[source_port].netdev;
return skb;
}
const struct dsa_device_ops lan9303_netdev_ops = {
.xmit = lan9303_xmit,
.rcv = lan9303_rcv,
};