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                dsa_alloc_etype_header(skb, BRCM_TAG_LEN);
 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                                       unsigned int offset)
 140{
 141        int source_port;
 142        u8 *brcm_tag;
 143
 144        if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 145                return NULL;
 146
 147        brcm_tag = skb->data - offset;
 148
 149        /* The opcode should never be different than 0b000 */
 150        if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 151                return NULL;
 152
 153        /* We should never see a reserved reason code without knowing how to
 154         * handle it
 155         */
 156        if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
 157                return NULL;
 158
 159        /* Locate which port this is coming from */
 160        source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 161
 162        skb->dev = dsa_master_find_slave(dev, 0, source_port);
 163        if (!skb->dev)
 164                return NULL;
 165
 166        /* Remove Broadcom tag and update checksum */
 167        skb_pull_rcsum(skb, BRCM_TAG_LEN);
 168
 169        dsa_default_offload_fwd_mark(skb);
 170
 171        return skb;
 172}
 173#endif
 174
 175#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 176static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
 177                                     struct net_device *dev)
 178{
 179        /* Build the tag after the MAC Source Address */
 180        return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
 181}
 182
 183
 184static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev)
 185{
 186        struct sk_buff *nskb;
 187
 188        /* skb->data points to the EtherType, the tag is right before it */
 189        nskb = brcm_tag_rcv_ll(skb, dev, 2);
 190        if (!nskb)
 191                return nskb;
 192
 193        dsa_strip_etype_header(skb, BRCM_TAG_LEN);
 194
 195        return nskb;
 196}
 197
 198static const struct dsa_device_ops brcm_netdev_ops = {
 199        .name   = "brcm",
 200        .proto  = DSA_TAG_PROTO_BRCM,
 201        .xmit   = brcm_tag_xmit,
 202        .rcv    = brcm_tag_rcv,
 203        .needed_headroom = BRCM_TAG_LEN,
 204};
 205
 206DSA_TAG_DRIVER(brcm_netdev_ops);
 207MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
 208#endif
 209
 210#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
 211static struct sk_buff *brcm_leg_tag_xmit(struct sk_buff *skb,
 212                                         struct net_device *dev)
 213{
 214        struct dsa_port *dp = dsa_slave_to_port(dev);
 215        u8 *brcm_tag;
 216
 217        /* The Ethernet switch we are interfaced with needs packets to be at
 218         * least 64 bytes (including FCS) otherwise they will be discarded when
 219         * they enter the switch port logic. When Broadcom tags are enabled, we
 220         * need to make sure that packets are at least 70 bytes
 221         * (including FCS and tag) because the length verification is done after
 222         * the Broadcom tag is stripped off the ingress packet.
 223         *
 224         * Let dsa_slave_xmit() free the SKB
 225         */
 226        if (__skb_put_padto(skb, ETH_ZLEN + BRCM_LEG_TAG_LEN, false))
 227                return NULL;
 228
 229        skb_push(skb, BRCM_LEG_TAG_LEN);
 230
 231        dsa_alloc_etype_header(skb, BRCM_LEG_TAG_LEN);
 232
 233        brcm_tag = skb->data + 2 * ETH_ALEN;
 234
 235        /* Broadcom tag type */
 236        brcm_tag[0] = BRCM_LEG_TYPE_HI;
 237        brcm_tag[1] = BRCM_LEG_TYPE_LO;
 238
 239        /* Broadcom tag value */
 240        brcm_tag[2] = BRCM_LEG_EGRESS;
 241        brcm_tag[3] = 0;
 242        brcm_tag[4] = 0;
 243        brcm_tag[5] = dp->index & BRCM_LEG_PORT_ID;
 244
 245        return skb;
 246}
 247
 248static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
 249                                        struct net_device *dev)
 250{
 251        int source_port;
 252        u8 *brcm_tag;
 253
 254        if (unlikely(!pskb_may_pull(skb, BRCM_LEG_PORT_ID)))
 255                return NULL;
 256
 257        brcm_tag = dsa_etype_header_pos_rx(skb);
 258
 259        source_port = brcm_tag[5] & BRCM_LEG_PORT_ID;
 260
 261        skb->dev = dsa_master_find_slave(dev, 0, source_port);
 262        if (!skb->dev)
 263                return NULL;
 264
 265        /* Remove Broadcom tag and update checksum */
 266        skb_pull_rcsum(skb, BRCM_LEG_TAG_LEN);
 267
 268        dsa_default_offload_fwd_mark(skb);
 269
 270        dsa_strip_etype_header(skb, BRCM_LEG_TAG_LEN);
 271
 272        return skb;
 273}
 274
 275static const struct dsa_device_ops brcm_legacy_netdev_ops = {
 276        .name = "brcm-legacy",
 277        .proto = DSA_TAG_PROTO_BRCM_LEGACY,
 278        .xmit = brcm_leg_tag_xmit,
 279        .rcv = brcm_leg_tag_rcv,
 280        .needed_headroom = BRCM_LEG_TAG_LEN,
 281};
 282
 283DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
 284MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY);
 285#endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
 286
 287#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 288static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
 289                                             struct net_device *dev)
 290{
 291        /* tag is prepended to the packet */
 292        return brcm_tag_xmit_ll(skb, dev, 0);
 293}
 294
 295static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 296                                            struct net_device *dev)
 297{
 298        /* tag is prepended to the packet */
 299        return brcm_tag_rcv_ll(skb, dev, ETH_HLEN);
 300}
 301
 302static const struct dsa_device_ops brcm_prepend_netdev_ops = {
 303        .name   = "brcm-prepend",
 304        .proto  = DSA_TAG_PROTO_BRCM_PREPEND,
 305        .xmit   = brcm_tag_xmit_prepend,
 306        .rcv    = brcm_tag_rcv_prepend,
 307        .needed_headroom = BRCM_TAG_LEN,
 308};
 309
 310DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
 311MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
 312#endif
 313
 314static struct dsa_tag_driver *dsa_tag_driver_array[] =  {
 315#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 316        &DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
 317#endif
 318#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
 319        &DSA_TAG_DRIVER_NAME(brcm_legacy_netdev_ops),
 320#endif
 321#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 322        &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
 323#endif
 324};
 325
 326module_dsa_tag_drivers(dsa_tag_driver_array);
 327
 328MODULE_LICENSE("GPL");
 329