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/dsa/brcm.h>
   9#include <linux/etherdevice.h>
  10#include <linux/list.h>
  11#include <linux/slab.h>
  12
  13#include "dsa_priv.h"
  14
  15/* Legacy Broadcom tag (6 bytes) */
  16#define BRCM_LEG_TAG_LEN        6
  17
  18/* Type fields */
  19/* 1st byte in the tag */
  20#define BRCM_LEG_TYPE_HI        0x88
  21/* 2nd byte in the tag */
  22#define BRCM_LEG_TYPE_LO        0x74
  23
  24/* Tag fields */
  25/* 3rd byte in the tag */
  26#define BRCM_LEG_UNICAST        (0 << 5)
  27#define BRCM_LEG_MULTICAST      (1 << 5)
  28#define BRCM_LEG_EGRESS         (2 << 5)
  29#define BRCM_LEG_INGRESS        (3 << 5)
  30
  31/* 6th byte in the tag */
  32#define BRCM_LEG_PORT_ID        (0xf)
  33
  34/* Newer Broadcom tag (4 bytes) */
  35#define BRCM_TAG_LEN    4
  36
  37/* Tag is constructed and desconstructed using byte by byte access
  38 * because the tag is placed after the MAC Source Address, which does
  39 * not make it 4-bytes aligned, so this might cause unaligned accesses
  40 * on most systems where this is used.
  41 */
  42
  43/* Ingress and egress opcodes */
  44#define BRCM_OPCODE_SHIFT       5
  45#define BRCM_OPCODE_MASK        0x7
  46
  47/* Ingress fields */
  48/* 1st byte in the tag */
  49#define BRCM_IG_TC_SHIFT        2
  50#define BRCM_IG_TC_MASK         0x7
  51/* 2nd byte in the tag */
  52#define BRCM_IG_TE_MASK         0x3
  53#define BRCM_IG_TS_SHIFT        7
  54/* 3rd byte in the tag */
  55#define BRCM_IG_DSTMAP2_MASK    1
  56#define BRCM_IG_DSTMAP1_MASK    0xff
  57
  58/* Egress fields */
  59
  60/* 2nd byte in the tag */
  61#define BRCM_EG_CID_MASK        0xff
  62
  63/* 3rd byte in the tag */
  64#define BRCM_EG_RC_MASK         0xff
  65#define  BRCM_EG_RC_RSVD        (3 << 6)
  66#define  BRCM_EG_RC_EXCEPTION   (1 << 5)
  67#define  BRCM_EG_RC_PROT_SNOOP  (1 << 4)
  68#define  BRCM_EG_RC_PROT_TERM   (1 << 3)
  69#define  BRCM_EG_RC_SWITCH      (1 << 2)
  70#define  BRCM_EG_RC_MAC_LEARN   (1 << 1)
  71#define  BRCM_EG_RC_MIRROR      (1 << 0)
  72#define BRCM_EG_TC_SHIFT        5
  73#define BRCM_EG_TC_MASK         0x7
  74#define BRCM_EG_PID_MASK        0x1f
  75
  76#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
  77        IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
  78
  79static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
  80                                        struct net_device *dev,
  81                                        unsigned int offset)
  82{
  83        struct dsa_port *dp = dsa_slave_to_port(dev);
  84        u16 queue = skb_get_queue_mapping(skb);
  85        u8 *brcm_tag;
  86
  87        /* The Ethernet switch we are interfaced with needs packets to be at
  88         * least 64 bytes (including FCS) otherwise they will be discarded when
  89         * they enter the switch port logic. When Broadcom tags are enabled, we
  90         * need to make sure that packets are at least 68 bytes
  91         * (including FCS and tag) because the length verification is done after
  92         * the Broadcom tag is stripped off the ingress packet.
  93         *
  94         * Let dsa_slave_xmit() free the SKB
  95         */
  96        if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
  97                return NULL;
  98
  99        skb_push(skb, BRCM_TAG_LEN);
 100
 101        if (offset)
 102                memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
 103
 104        brcm_tag = skb->data + offset;
 105
 106        /* Set the ingress opcode, traffic class, tag enforcment is
 107         * deprecated
 108         */
 109        brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
 110                       ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
 111        brcm_tag[1] = 0;
 112        brcm_tag[2] = 0;
 113        if (dp->index == 8)
 114                brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
 115        brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
 116
 117        /* Now tell the master network device about the desired output queue
 118         * as well
 119         */
 120        skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
 121
 122        return skb;
 123}
 124
 125/* Frames with this tag have one of these two layouts:
 126 * -----------------------------------
 127 * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
 128 * -----------------------------------
 129 * -----------------------------------
 130 * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
 131 * -----------------------------------
 132 * In both cases, at receive time, skb->data points 2 bytes before the actual
 133 * Ethernet type field and we have an offset of 4bytes between where skb->data
 134 * and where the payload starts. So the same low-level receive function can be
 135 * used.
 136 */
 137static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 138                                       struct net_device *dev,
 139                                       struct packet_type *pt,
 140                                       unsigned int offset)
 141{
 142        int source_port;
 143        u8 *brcm_tag;
 144
 145        if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 146                return NULL;
 147
 148        brcm_tag = skb->data - offset;
 149
 150        /* The opcode should never be different than 0b000 */
 151        if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 152                return NULL;
 153
 154        /* We should never see a reserved reason code without knowing how to
 155         * handle it
 156         */
 157        if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
 158                return NULL;
 159
 160        /* Locate which port this is coming from */
 161        source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 162
 163        skb->dev = dsa_master_find_slave(dev, 0, source_port);
 164        if (!skb->dev)
 165                return NULL;
 166
 167        /* Remove Broadcom tag and update checksum */
 168        skb_pull_rcsum(skb, BRCM_TAG_LEN);
 169
 170        skb->offload_fwd_mark = 1;
 171
 172        return skb;
 173}
 174#endif
 175
 176#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 177static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
 178                                     struct net_device *dev)
 179{
 180        /* Build the tag after the MAC Source Address */
 181        return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
 182}
 183
 184
 185static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 186                                    struct packet_type *pt)
 187{
 188        struct sk_buff *nskb;
 189
 190        /* skb->data points to the EtherType, the tag is right before it */
 191        nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
 192        if (!nskb)
 193                return nskb;
 194
 195        /* Move the Ethernet DA and SA */
 196        memmove(nskb->data - ETH_HLEN,
 197                nskb->data - ETH_HLEN - BRCM_TAG_LEN,
 198                2 * ETH_ALEN);
 199
 200        return nskb;
 201}
 202
 203static const struct dsa_device_ops brcm_netdev_ops = {
 204        .name   = "brcm",
 205        .proto  = DSA_TAG_PROTO_BRCM,
 206        .xmit   = brcm_tag_xmit,
 207        .rcv    = brcm_tag_rcv,
 208        .needed_headroom = BRCM_TAG_LEN,
 209};
 210
 211DSA_TAG_DRIVER(brcm_netdev_ops);
 212MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
 213#endif
 214
 215#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
 216static struct sk_buff *brcm_leg_tag_xmit(struct sk_buff *skb,
 217                                         struct net_device *dev)
 218{
 219        struct dsa_port *dp = dsa_slave_to_port(dev);
 220        u8 *brcm_tag;
 221
 222        /* The Ethernet switch we are interfaced with needs packets to be at
 223         * least 64 bytes (including FCS) otherwise they will be discarded when
 224         * they enter the switch port logic. When Broadcom tags are enabled, we
 225         * need to make sure that packets are at least 70 bytes
 226         * (including FCS and tag) because the length verification is done after
 227         * the Broadcom tag is stripped off the ingress packet.
 228         *
 229         * Let dsa_slave_xmit() free the SKB
 230         */
 231        if (__skb_put_padto(skb, ETH_ZLEN + BRCM_LEG_TAG_LEN, false))
 232                return NULL;
 233
 234        skb_push(skb, BRCM_LEG_TAG_LEN);
 235
 236        memmove(skb->data, skb->data + BRCM_LEG_TAG_LEN, 2 * ETH_ALEN);
 237
 238        brcm_tag = skb->data + 2 * ETH_ALEN;
 239
 240        /* Broadcom tag type */
 241        brcm_tag[0] = BRCM_LEG_TYPE_HI;
 242        brcm_tag[1] = BRCM_LEG_TYPE_LO;
 243
 244        /* Broadcom tag value */
 245        brcm_tag[2] = BRCM_LEG_EGRESS;
 246        brcm_tag[3] = 0;
 247        brcm_tag[4] = 0;
 248        brcm_tag[5] = dp->index & BRCM_LEG_PORT_ID;
 249
 250        return skb;
 251}
 252
 253static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
 254                                        struct net_device *dev,
 255                                        struct packet_type *pt)
 256{
 257        int source_port;
 258        u8 *brcm_tag;
 259
 260        if (unlikely(!pskb_may_pull(skb, BRCM_LEG_PORT_ID)))
 261                return NULL;
 262
 263        brcm_tag = skb->data - 2;
 264
 265        source_port = brcm_tag[5] & BRCM_LEG_PORT_ID;
 266
 267        skb->dev = dsa_master_find_slave(dev, 0, source_port);
 268        if (!skb->dev)
 269                return NULL;
 270
 271        /* Remove Broadcom tag and update checksum */
 272        skb_pull_rcsum(skb, BRCM_LEG_TAG_LEN);
 273
 274        skb->offload_fwd_mark = 1;
 275
 276        /* Move the Ethernet DA and SA */
 277        memmove(skb->data - ETH_HLEN,
 278                skb->data - ETH_HLEN - BRCM_LEG_TAG_LEN,
 279                2 * ETH_ALEN);
 280
 281        return skb;
 282}
 283
 284static const struct dsa_device_ops brcm_legacy_netdev_ops = {
 285        .name = "brcm-legacy",
 286        .proto = DSA_TAG_PROTO_BRCM_LEGACY,
 287        .xmit = brcm_leg_tag_xmit,
 288        .rcv = brcm_leg_tag_rcv,
 289        .needed_headroom = BRCM_LEG_TAG_LEN,
 290};
 291
 292DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
 293MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY);
 294#endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
 295
 296#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 297static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
 298                                             struct net_device *dev)
 299{
 300        /* tag is prepended to the packet */
 301        return brcm_tag_xmit_ll(skb, dev, 0);
 302}
 303
 304static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 305                                            struct net_device *dev,
 306                                            struct packet_type *pt)
 307{
 308        /* tag is prepended to the packet */
 309        return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
 310}
 311
 312static const struct dsa_device_ops brcm_prepend_netdev_ops = {
 313        .name   = "brcm-prepend",
 314        .proto  = DSA_TAG_PROTO_BRCM_PREPEND,
 315        .xmit   = brcm_tag_xmit_prepend,
 316        .rcv    = brcm_tag_rcv_prepend,
 317        .needed_headroom = BRCM_TAG_LEN,
 318};
 319
 320DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
 321MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
 322#endif
 323
 324static struct dsa_tag_driver *dsa_tag_driver_array[] =  {
 325#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 326        &DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
 327#endif
 328#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
 329        &DSA_TAG_DRIVER_NAME(brcm_legacy_netdev_ops),
 330#endif
 331#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 332        &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
 333#endif
 334};
 335
 336module_dsa_tag_drivers(dsa_tag_driver_array);
 337
 338MODULE_LICENSE("GPL");
 339