LXR linux/net/dsa/tag

   1/*
   2 * Broadcom tag support
   3 *
   4 * Copyright (C) 2014 Broadcom Corporation
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 */
  11
  12#include <linux/etherdevice.h>
  13#include <linux/list.h>
  14#include <linux/slab.h>
  15
  16#include "dsa_priv.h"
  17
  18/* This tag length is 4 bytes, older ones were 6 bytes, we do not
  19 * handle them
  20 */
  21#define BRCM_TAG_LEN    4
  22
  23/* Tag is constructed and desconstructed using byte by byte access
  24 * because the tag is placed after the MAC Source Address, which does
  25 * not make it 4-bytes aligned, so this might cause unaligned accesses
  26 * on most systems where this is used.
  27 */
  28
  29/* Ingress and egress opcodes */
  30#define BRCM_OPCODE_SHIFT       5
  31#define BRCM_OPCODE_MASK        0x7
  32
  33/* Ingress fields */
  34/* 1st byte in the tag */
  35#define BRCM_IG_TC_SHIFT        2
  36#define BRCM_IG_TC_MASK         0x7
  37/* 2nd byte in the tag */
  38#define BRCM_IG_TE_MASK         0x3
  39#define BRCM_IG_TS_SHIFT        7
  40/* 3rd byte in the tag */
  41#define BRCM_IG_DSTMAP2_MASK    1
  42#define BRCM_IG_DSTMAP1_MASK    0xff
  43
  44/* Egress fields */
  45
  46/* 2nd byte in the tag */
  47#define BRCM_EG_CID_MASK        0xff
  48
  49/* 3rd byte in the tag */
  50#define BRCM_EG_RC_MASK         0xff
  51#define  BRCM_EG_RC_RSVD        (3 << 6)
  52#define  BRCM_EG_RC_EXCEPTION   (1 << 5)
  53#define  BRCM_EG_RC_PROT_SNOOP  (1 << 4)
  54#define  BRCM_EG_RC_PROT_TERM   (1 << 3)
  55#define  BRCM_EG_RC_SWITCH      (1 << 2)
  56#define  BRCM_EG_RC_MAC_LEARN   (1 << 1)
  57#define  BRCM_EG_RC_MIRROR      (1 << 0)
  58#define BRCM_EG_TC_SHIFT        5
  59#define BRCM_EG_TC_MASK         0x7
  60#define BRCM_EG_PID_MASK        0x1f
  61
  62static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
  63                                        struct net_device *dev,
  64                                        unsigned int offset)
  65{
  66        struct dsa_port *dp = dsa_slave_to_port(dev);
  67        u16 queue = skb_get_queue_mapping(skb);
  68        u8 *brcm_tag;
  69
  70        if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
  71                return NULL;
  72
  73        /* The Ethernet switch we are interfaced with needs packets to be at
  74         * least 64 bytes (including FCS) otherwise they will be discarded when
  75         * they enter the switch port logic. When Broadcom tags are enabled, we
  76         * need to make sure that packets are at least 68 bytes
  77         * (including FCS and tag) because the length verification is done after
  78         * the Broadcom tag is stripped off the ingress packet.
  79         *
  80         * Let dsa_slave_xmit() free the SKB
  81         */
  82        if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
  83                return NULL;
  84
  85        skb_push(skb, BRCM_TAG_LEN);
  86
  87        if (offset)
  88                memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
  89
  90        brcm_tag = skb->data + offset;
  91
  92        /* Set the ingress opcode, traffic class, tag enforcment is
  93         * deprecated
  94         */
  95        brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
  96                       ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
  97        brcm_tag[1] = 0;
  98        brcm_tag[2] = 0;
  99        if (dp->index == 8)
 100                brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
 101        brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
 102
 103        /* Now tell the master network device about the desired output queue
 104         * as well
 105         */
 106        skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
 107
 108        return skb;
 109}
 110
 111static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 112                                       struct net_device *dev,
 113                                       struct packet_type *pt,
 114                                       unsigned int offset)
 115{
 116        int source_port;
 117        u8 *brcm_tag;
 118
 119        if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 120                return NULL;
 121
 122        brcm_tag = skb->data - offset;
 123
 124        /* The opcode should never be different than 0b000 */
 125        if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 126                return NULL;
 127
 128        /* We should never see a reserved reason code without knowing how to
 129         * handle it
 130         */
 131        if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
 132                return NULL;
 133
 134        /* Locate which port this is coming from */
 135        source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 136
 137        skb->dev = dsa_master_find_slave(dev, 0, source_port);
 138        if (!skb->dev)
 139                return NULL;
 140
 141        /* Remove Broadcom tag and update checksum */
 142        skb_pull_rcsum(skb, BRCM_TAG_LEN);
 143
 144        return skb;
 145}
 146
 147#ifdef 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
 174const struct dsa_device_ops brcm_netdev_ops = {
 175        .xmit   = brcm_tag_xmit,
 176        .rcv    = brcm_tag_rcv,
 177};
 178#endif
 179
 180#ifdef CONFIG_NET_DSA_TAG_BRCM_PREPEND
 181static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
 182                                             struct net_device *dev)
 183{
 184        /* tag is prepended to the packet */
 185        return brcm_tag_xmit_ll(skb, dev, 0);
 186}
 187
 188static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 189                                            struct net_device *dev,
 190                                            struct packet_type *pt)
 191{
 192        /* tag is prepended to the packet */
 193        return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
 194}
 195
 196const struct dsa_device_ops brcm_prepend_netdev_ops = {
 197        .xmit   = brcm_tag_xmit_prepend,
 198        .rcv    = brcm_tag_rcv_prepend,
 199};
 200#endif
 201