LXR linux/net/dsa/tag

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Broadcom tag support
   4 *
   5 * Copyright (C) 2014 Broadcom Corporation
   6 */
   7
   8#include <linux/etherdevice.h>
   9#include <linux/list.h>
  10#include <linux/slab.h>
  11
  12#include "dsa_priv.h"
  13
  14/* This tag length is 4 bytes, older ones were 6 bytes, we do not
  15 * handle them
  16 */
  17#define BRCM_TAG_LEN    4
  18
  19/* Tag is constructed and desconstructed using byte by byte access
  20 * because the tag is placed after the MAC Source Address, which does
  21 * not make it 4-bytes aligned, so this might cause unaligned accesses
  22 * on most systems where this is used.
  23 */
  24
  25/* Ingress and egress opcodes */
  26#define BRCM_OPCODE_SHIFT       5
  27#define BRCM_OPCODE_MASK        0x7
  28
  29/* Ingress fields */
  30/* 1st byte in the tag */
  31#define BRCM_IG_TC_SHIFT        2
  32#define BRCM_IG_TC_MASK         0x7
  33/* 2nd byte in the tag */
  34#define BRCM_IG_TE_MASK         0x3
  35#define BRCM_IG_TS_SHIFT        7
  36/* 3rd byte in the tag */
  37#define BRCM_IG_DSTMAP2_MASK    1
  38#define BRCM_IG_DSTMAP1_MASK    0xff
  39
  40/* Egress fields */
  41
  42/* 2nd byte in the tag */
  43#define BRCM_EG_CID_MASK        0xff
  44
  45/* 3rd byte in the tag */
  46#define BRCM_EG_RC_MASK         0xff
  47#define  BRCM_EG_RC_RSVD        (3 << 6)
  48#define  BRCM_EG_RC_EXCEPTION   (1 << 5)
  49#define  BRCM_EG_RC_PROT_SNOOP  (1 << 4)
  50#define  BRCM_EG_RC_PROT_TERM   (1 << 3)
  51#define  BRCM_EG_RC_SWITCH      (1 << 2)
  52#define  BRCM_EG_RC_MAC_LEARN   (1 << 1)
  53#define  BRCM_EG_RC_MIRROR      (1 << 0)
  54#define BRCM_EG_TC_SHIFT        5
  55#define BRCM_EG_TC_MASK         0x7
  56#define BRCM_EG_PID_MASK        0x1f
  57
  58#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
  59        IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
  60
  61static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
  62                                        struct net_device *dev,
  63                                        unsigned int offset)
  64{
  65        struct dsa_port *dp = dsa_slave_to_port(dev);
  66        u16 queue = skb_get_queue_mapping(skb);
  67        u8 *brcm_tag;
  68
  69        if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
  70                return NULL;
  71
  72        /* The Ethernet switch we are interfaced with needs packets to be at
  73         * least 64 bytes (including FCS) otherwise they will be discarded when
  74         * they enter the switch port logic. When Broadcom tags are enabled, we
  75         * need to make sure that packets are at least 68 bytes
  76         * (including FCS and tag) because the length verification is done after
  77         * the Broadcom tag is stripped off the ingress packet.
  78         *
  79         * Let dsa_slave_xmit() free the SKB
  80         */
  81        if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
  82                return NULL;
  83
  84        skb_push(skb, BRCM_TAG_LEN);
  85
  86        if (offset)
  87                memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
  88
  89        brcm_tag = skb->data + offset;
  90
  91        /* Set the ingress opcode, traffic class, tag enforcment is
  92         * deprecated
  93         */
  94        brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
  95                       ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
  96        brcm_tag[1] = 0;
  97        brcm_tag[2] = 0;
  98        if (dp->index == 8)
  99                brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
 100        brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
 101
 102        /* Now tell the master network device about the desired output queue
 103         * as well
 104         */
 105        skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
 106
 107        return skb;
 108}
 109
 110static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 111                                       struct net_device *dev,
 112                                       struct packet_type *pt,
 113                                       unsigned int offset)
 114{
 115        int source_port;
 116        u8 *brcm_tag;
 117
 118        if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 119                return NULL;
 120
 121        brcm_tag = skb->data - offset;
 122
 123        /* The opcode should never be different than 0b000 */
 124        if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 125                return NULL;
 126
 127        /* We should never see a reserved reason code without knowing how to
 128         * handle it
 129         */
 130        if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
 131                return NULL;
 132
 133        /* Locate which port this is coming from */
 134        source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 135
 136        skb->dev = dsa_master_find_slave(dev, 0, source_port);
 137        if (!skb->dev)
 138                return NULL;
 139
 140        /* Remove Broadcom tag and update checksum */
 141        skb_pull_rcsum(skb, BRCM_TAG_LEN);
 142
 143        return skb;
 144}
 145#endif
 146
 147#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 148static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
 149                                     struct net_device *dev)
 150{
 151        /* Build the tag after the MAC Source Address */
 152        return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
 153}
 154
 155
 156static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 157                                    struct packet_type *pt)
 158{
 159        struct sk_buff *nskb;
 160
 161        /* skb->data points to the EtherType, the tag is right before it */
 162        nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
 163        if (!nskb)
 164                return nskb;
 165
 166        /* Move the Ethernet DA and SA */
 167        memmove(nskb->data - ETH_HLEN,
 168                nskb->data - ETH_HLEN - BRCM_TAG_LEN,
 169                2 * ETH_ALEN);
 170
 171        return nskb;
 172}
 173
 174static const struct dsa_device_ops brcm_netdev_ops = {
 175        .name   = "brcm",
 176        .proto  = DSA_TAG_PROTO_BRCM,
 177        .xmit   = brcm_tag_xmit,
 178        .rcv    = brcm_tag_rcv,
 179        .overhead = BRCM_TAG_LEN,
 180};
 181
 182DSA_TAG_DRIVER(brcm_netdev_ops);
 183MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
 184#endif
 185
 186#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 187static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
 188                                             struct net_device *dev)
 189{
 190        /* tag is prepended to the packet */
 191        return brcm_tag_xmit_ll(skb, dev, 0);
 192}
 193
 194static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 195                                            struct net_device *dev,
 196                                            struct packet_type *pt)
 197{
 198        /* tag is prepended to the packet */
 199        return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
 200}
 201
 202static const struct dsa_device_ops brcm_prepend_netdev_ops = {
 203        .name   = "brcm-prepend",
 204        .proto  = DSA_TAG_PROTO_BRCM_PREPEND,
 205        .xmit   = brcm_tag_xmit_prepend,
 206        .rcv    = brcm_tag_rcv_prepend,
 207        .overhead = BRCM_TAG_LEN,
 208};
 209
 210DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
 211MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
 212#endif
 213
 214static struct dsa_tag_driver *dsa_tag_driver_array[] =  {
 215#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 216        &DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
 217#endif
 218#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 219        &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
 220#endif
 221};
 222
 223module_dsa_tag_drivers(dsa_tag_driver_array);
 224
 225MODULE_LICENSE("GPL");
 226