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// SPDX-License-Identifier: GPL-2.0+
/*
* Broadcom tag support
*
* Copyright (C) 2014 Broadcom Corporation
*/
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/slab.h>
#include "dsa_priv.h"
/* This tag length is 4 bytes, older ones were 6 bytes, we do not
* handle them
*/
#define BRCM_TAG_LEN 4
/* Tag is constructed and desconstructed using byte by byte access
* because the tag is placed after the MAC Source Address, which does
* not make it 4-bytes aligned, so this might cause unaligned accesses
* on most systems where this is used.
*/
/* Ingress and egress opcodes */
#define BRCM_OPCODE_SHIFT 5
#define BRCM_OPCODE_MASK 0x7
/* Ingress fields */
/* 1st byte in the tag */
#define BRCM_IG_TC_SHIFT 2
#define BRCM_IG_TC_MASK 0x7
/* 2nd byte in the tag */
#define BRCM_IG_TE_MASK 0x3
#define BRCM_IG_TS_SHIFT 7
/* 3rd byte in the tag */
#define BRCM_IG_DSTMAP2_MASK 1
#define BRCM_IG_DSTMAP1_MASK 0xff
/* Egress fields */
/* 2nd byte in the tag */
#define BRCM_EG_CID_MASK 0xff
/* 3rd byte in the tag */
#define BRCM_EG_RC_MASK 0xff
#define BRCM_EG_RC_RSVD (3 << 6)
#define BRCM_EG_RC_EXCEPTION (1 << 5)
#define BRCM_EG_RC_PROT_SNOOP (1 << 4)
#define BRCM_EG_RC_PROT_TERM (1 << 3)
#define BRCM_EG_RC_SWITCH (1 << 2)
#define BRCM_EG_RC_MAC_LEARN (1 << 1)
#define BRCM_EG_RC_MIRROR (1 << 0)
#define BRCM_EG_TC_SHIFT 5
#define BRCM_EG_TC_MASK 0x7
#define BRCM_EG_PID_MASK 0x1f
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
struct net_device *dev,
unsigned int offset)
{
struct dsa_port *dp = dsa_slave_to_port(dev);
u16 queue = skb_get_queue_mapping(skb);
u8 *brcm_tag;
if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
return NULL;
/* The Ethernet switch we are interfaced with needs packets to be at
* least 64 bytes (including FCS) otherwise they will be discarded when
* they enter the switch port logic. When Broadcom tags are enabled, we
* need to make sure that packets are at least 68 bytes
* (including FCS and tag) because the length verification is done after
* the Broadcom tag is stripped off the ingress packet.
*
* Let dsa_slave_xmit() free the SKB
*/
if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
return NULL;
skb_push(skb, BRCM_TAG_LEN);
if (offset)
memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
brcm_tag = skb->data + offset;
/* Set the ingress opcode, traffic class, tag enforcment is
* deprecated
*/
brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
brcm_tag[1] = 0;
brcm_tag[2] = 0;
if (dp->index == 8)
brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
/* Now tell the master network device about the desired output queue
* as well
*/
skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
return skb;
}
static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
struct net_device *dev,
struct packet_type *pt,
unsigned int offset)
{
int source_port;
u8 *brcm_tag;
if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
return NULL;
brcm_tag = skb->data - offset;
/* The opcode should never be different than 0b000 */
if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
return NULL;
/* We should never see a reserved reason code without knowing how to
* handle it
*/
if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
return NULL;
/* Locate which port this is coming from */
source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
skb->dev = dsa_master_find_slave(dev, 0, source_port);
if (!skb->dev)
return NULL;
/* Remove Broadcom tag and update checksum */
skb_pull_rcsum(skb, BRCM_TAG_LEN);
return skb;
}
static int brcm_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
int *offset)
{
/* We have been called on the DSA master network device after
* eth_type_trans() which pulled the Ethernet header already.
* Frames have one of these two layouts:
* -----------------------------------
* | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
* -----------------------------------
* -----------------------------------
* | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
* -----------------------------------
* skb->data points 2 bytes before the actual Ethernet type field and
* we have an offset of 4bytes between where skb->data and where the
* payload starts.
*/
*offset = BRCM_TAG_LEN;
*proto = ((__be16 *)skb->data)[1];
return 0;
}
#endif
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
struct net_device *dev)
{
/* Build the tag after the MAC Source Address */
return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
}
static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt)
{
struct sk_buff *nskb;
/* skb->data points to the EtherType, the tag is right before it */
nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
if (!nskb)
return nskb;
/* Move the Ethernet DA and SA */
memmove(nskb->data - ETH_HLEN,
nskb->data - ETH_HLEN - BRCM_TAG_LEN,
2 * ETH_ALEN);
return nskb;
}
static const struct dsa_device_ops brcm_netdev_ops = {
.name = "brcm",
.proto = DSA_TAG_PROTO_BRCM,
.xmit = brcm_tag_xmit,
.rcv = brcm_tag_rcv,
.overhead = BRCM_TAG_LEN,
.flow_dissect = brcm_tag_flow_dissect,
};
DSA_TAG_DRIVER(brcm_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
#endif
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
struct net_device *dev)
{
/* tag is prepended to the packet */
return brcm_tag_xmit_ll(skb, dev, 0);
}
static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
struct net_device *dev,
struct packet_type *pt)
{
/* tag is prepended to the packet */
return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
}
static const struct dsa_device_ops brcm_prepend_netdev_ops = {
.name = "brcm-prepend",
.proto = DSA_TAG_PROTO_BRCM_PREPEND,
.xmit = brcm_tag_xmit_prepend,
.rcv = brcm_tag_rcv_prepend,
.overhead = BRCM_TAG_LEN,
.flow_dissect = brcm_tag_flow_dissect,
};
DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
#endif
static struct dsa_tag_driver *dsa_tag_driver_array[] = {
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
&DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
#endif
#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
&DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
#endif
};
module_dsa_tag_drivers(dsa_tag_driver_array);
MODULE_LICENSE("GPL");
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