net/dsa/tag_brcm.c

   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/if_vlan.h>
  11 #include <linux/list.h>
  12 #include <linux/slab.h>
  13
  14 #include "tag.h"
  15
  16 #define BRCM_NAME               "brcm"
  17 #define BRCM_LEGACY_NAME        "brcm-legacy"
  18 #define BRCM_PREPEND_NAME       "brcm-prepend"
  19
  20 /* Legacy Broadcom tag (6 bytes) */
  21 #define BRCM_LEG_TAG_LEN        6
  22
  23 /* Type fields */
  24 /* 1st byte in the tag */
  25 #define BRCM_LEG_TYPE_HI        0x88
  26 /* 2nd byte in the tag */
  27 #define BRCM_LEG_TYPE_LO        0x74
  28
  29 /* Tag fields */
  30 /* 3rd byte in the tag */
  31 #define BRCM_LEG_UNICAST        (0 << 5)
  32 #define BRCM_LEG_MULTICAST      (1 << 5)
  33 #define BRCM_LEG_EGRESS         (2 << 5)
  34 #define BRCM_LEG_INGRESS        (3 << 5)
  35
  36 /* 6th byte in the tag */
  37 #define BRCM_LEG_PORT_ID        (0xf)
  38
  39 /* Newer Broadcom tag (4 bytes) */
  40 #define BRCM_TAG_LEN    4
  41
  42 /* Tag is constructed and deconstructed using byte by byte access
  43  * because the tag is placed after the MAC Source Address, which does
  44  * not make it 4-bytes aligned, so this might cause unaligned accesses
  45  * on most systems where this is used.
  46  */
  47
  48 /* Ingress and egress opcodes */
  49 #define BRCM_OPCODE_SHIFT       5
  50 #define BRCM_OPCODE_MASK        0x7
  51
  52 /* Ingress fields */
  53 /* 1st byte in the tag */
  54 #define BRCM_IG_TC_SHIFT        2
  55 #define BRCM_IG_TC_MASK         0x7
  56 /* 2nd byte in the tag */
  57 #define BRCM_IG_TE_MASK         0x3
  58 #define BRCM_IG_TS_SHIFT        7
  59 /* 3rd byte in the tag */
  60 #define BRCM_IG_DSTMAP2_MASK    1
  61 #define BRCM_IG_DSTMAP1_MASK    0xff
  62
  63 /* Egress fields */
  64
  65 /* 2nd byte in the tag */
  66 #define BRCM_EG_CID_MASK        0xff
  67
  68 /* 3rd byte in the tag */
  69 #define BRCM_EG_RC_MASK         0xff
  70 #define  BRCM_EG_RC_RSVD        (3 << 6)
  71 #define  BRCM_EG_RC_EXCEPTION   (1 << 5)
  72 #define  BRCM_EG_RC_PROT_SNOOP  (1 << 4)
  73 #define  BRCM_EG_RC_PROT_TERM   (1 << 3)
  74 #define  BRCM_EG_RC_SWITCH      (1 << 2)
  75 #define  BRCM_EG_RC_MAC_LEARN   (1 << 1)
  76 #define  BRCM_EG_RC_MIRROR      (1 << 0)
  77 #define BRCM_EG_TC_SHIFT        5
  78 #define BRCM_EG_TC_MASK         0x7
  79 #define BRCM_EG_PID_MASK        0x1f
  80
  81 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
  82         IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
  83
  84 static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
  85                                         struct net_device *dev,
  86                                         unsigned int offset)
  87 {
  88         struct dsa_port *dp = dsa_user_to_port(dev);
  89         u16 queue = skb_get_queue_mapping(skb);
  90         u8 *brcm_tag;
  91
  92         /* The Ethernet switch we are interfaced with needs packets to be at
  93          * least 64 bytes (including FCS) otherwise they will be discarded when
  94          * they enter the switch port logic. When Broadcom tags are enabled, we
  95          * need to make sure that packets are at least 68 bytes
  96          * (including FCS and tag) because the length verification is done after
  97          * the Broadcom tag is stripped off the ingress packet.
  98          *
  99          * Let dsa_user_xmit() free the SKB
 100          */
 101         if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
 102                 return NULL;
 103
 104         skb_push(skb, BRCM_TAG_LEN);
 105
 106         if (offset)
 107                 dsa_alloc_etype_header(skb, BRCM_TAG_LEN);
 108
 109         brcm_tag = skb->data + offset;
 110
 111         /* Set the ingress opcode, traffic class, tag enforcement is
 112          * deprecated
 113          */
 114         brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
 115                        ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
 116         brcm_tag[1] = 0;
 117         brcm_tag[2] = 0;
 118         if (dp->index == 8)
 119                 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
 120         brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
 121
 122         /* Now tell the conduit network device about the desired output queue
 123          * as well
 124          */
 125         skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
 126
 127         return skb;
 128 }
 129
 130 /* Frames with this tag have one of these two layouts:
 131  * -----------------------------------
 132  * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
 133  * -----------------------------------
 134  * -----------------------------------
 135  * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
 136  * -----------------------------------
 137  * In both cases, at receive time, skb->data points 2 bytes before the actual
 138  * Ethernet type field and we have an offset of 4bytes between where skb->data
 139  * and where the payload starts. So the same low-level receive function can be
 140  * used.
 141  */
 142 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 143                                        struct net_device *dev,
 144                                        unsigned int offset)
 145 {
 146         int source_port;
 147         u8 *brcm_tag;
 148
 149         if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 150                 return NULL;
 151
 152         brcm_tag = skb->data - offset;
 153
 154         /* The opcode should never be different than 0b000 */
 155         if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 156                 return NULL;
 157
 158         /* We should never see a reserved reason code without knowing how to
 159          * handle it
 160          */
 161         if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
 162                 return NULL;
 163
 164         /* Locate which port this is coming from */
 165         source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 166
 167         skb->dev = dsa_conduit_find_user(dev, 0, source_port);
 168         if (!skb->dev)
 169                 return NULL;
 170
 171         /* Remove Broadcom tag and update checksum */
 172         skb_pull_rcsum(skb, BRCM_TAG_LEN);
 173
 174         dsa_default_offload_fwd_mark(skb);
 175
 176         return skb;
 177 }
 178 #endif
 179
 180 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
 181 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
 182                                      struct net_device *dev)
 183 {
 184         /* Build the tag after the MAC Source Address */
 185         return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
 186 }
 187
 188
 189 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev)
 190 {
 191         struct sk_buff *nskb;
 192
 193         /* skb->data points to the EtherType, the tag is right before it */
 194         nskb = brcm_tag_rcv_ll(skb, dev, 2);
 195         if (!nskb)
 196                 return nskb;
 197
 198         dsa_strip_etype_header(skb, BRCM_TAG_LEN);
 199
 200         return nskb;
 201 }
 202
 203 static const struct dsa_device_ops brcm_netdev_ops = {
 204         .name   = BRCM_NAME,
 205         .proto  = DSA_TAG_PROTO_BRCM,
 206         .xmit   = brcm_tag_xmit,
 207         .rcv    = brcm_tag_rcv,
 208         .needed_headroom = BRCM_TAG_LEN,
 209 };
 210
 211 DSA_TAG_DRIVER(brcm_netdev_ops);
 212 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM, BRCM_NAME);
 213 #endif
 214
 215 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
 216 static struct sk_buff *brcm_leg_tag_xmit(struct sk_buff *skb,
 217                                          struct net_device *dev)
 218 {
 219         struct dsa_port *dp = dsa_user_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_user_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         dsa_alloc_etype_header(skb, BRCM_LEG_TAG_LEN);
 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
 253 static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
 254                                         struct net_device *dev)
 255 {
 256         int len = BRCM_LEG_TAG_LEN;
 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 = dsa_etype_header_pos_rx(skb);
 264
 265         source_port = brcm_tag[5] & BRCM_LEG_PORT_ID;
 266
 267         skb->dev = dsa_conduit_find_user(dev, 0, source_port);
 268         if (!skb->dev)
 269                 return NULL;
 270
 271         /* VLAN tag is added by BCM63xx internal switch */
 272         if (netdev_uses_dsa(skb->dev))
 273                 len += VLAN_HLEN;
 274
 275         /* Remove Broadcom tag and update checksum */
 276         skb_pull_rcsum(skb, len);
 277
 278         dsa_default_offload_fwd_mark(skb);
 279
 280         dsa_strip_etype_header(skb, len);
 281
 282         return skb;
 283 }
 284
 285 static const struct dsa_device_ops brcm_legacy_netdev_ops = {
 286         .name = BRCM_LEGACY_NAME,
 287         .proto = DSA_TAG_PROTO_BRCM_LEGACY,
 288         .xmit = brcm_leg_tag_xmit,
 289         .rcv = brcm_leg_tag_rcv,
 290         .needed_headroom = BRCM_LEG_TAG_LEN,
 291 };
 292
 293 DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
 294 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY, BRCM_LEGACY_NAME);
 295 #endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
 296
 297 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
 298 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
 299                                              struct net_device *dev)
 300 {
 301         /* tag is prepended to the packet */
 302         return brcm_tag_xmit_ll(skb, dev, 0);
 303 }
 304
 305 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 306                                             struct net_device *dev)
 307 {
 308         /* tag is prepended to the packet */
 309         return brcm_tag_rcv_ll(skb, dev, ETH_HLEN);
 310 }
 311
 312 static const struct dsa_device_ops brcm_prepend_netdev_ops = {
 313         .name   = BRCM_PREPEND_NAME,
 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
 320 DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
 321 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND, BRCM_PREPEND_NAME);
 322 #endif
 323
 324 static 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
 336 module_dsa_tag_drivers(dsa_tag_driver_array);
 337
 338 MODULE_DESCRIPTION("DSA tag driver for Broadcom switches using in-frame headers");
 339 MODULE_LICENSE("GPL");