net/dsa/tag_brcm.c

   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 #include "dsa_priv.h"
  16
  17 /* This tag length is 4 bytes, older ones were 6 bytes, we do not
  18  * handle them
  19  */
  20 #define BRCM_TAG_LEN    4
  21
  22 /* Tag is constructed and desconstructed using byte by byte access
  23  * because the tag is placed after the MAC Source Address, which does
  24  * not make it 4-bytes aligned, so this might cause unaligned accesses
  25  * on most systems where this is used.
  26  */
  27
  28 /* Ingress and egress opcodes */
  29 #define BRCM_OPCODE_SHIFT       5
  30 #define BRCM_OPCODE_MASK        0x7
  31
  32 /* Ingress fields */
  33 /* 1st byte in the tag */
  34 #define BRCM_IG_TC_SHIFT        2
  35 #define BRCM_IG_TC_MASK         0x7
  36 /* 2nd byte in the tag */
  37 #define BRCM_IG_TE_MASK         0x3
  38 #define BRCM_IG_TS_SHIFT        7
  39 /* 3rd byte in the tag */
  40 #define BRCM_IG_DSTMAP2_MASK    1
  41 #define BRCM_IG_DSTMAP1_MASK    0xff
  42
  43 /* Egress fields */
  44
  45 /* 2nd byte in the tag */
  46 #define BRCM_EG_CID_MASK        0xff
  47
  48 /* 3rd byte in the tag */
  49 #define BRCM_EG_RC_MASK         0xff
  50 #define  BRCM_EG_RC_RSVD        (3 << 6)
  51 #define  BRCM_EG_RC_EXCEPTION   (1 << 5)
  52 #define  BRCM_EG_RC_PROT_SNOOP  (1 << 4)
  53 #define  BRCM_EG_RC_PROT_TERM   (1 << 3)
  54 #define  BRCM_EG_RC_SWITCH      (1 << 2)
  55 #define  BRCM_EG_RC_MAC_LEARN   (1 << 1)
  56 #define  BRCM_EG_RC_MIRROR      (1 << 0)
  57 #define BRCM_EG_TC_SHIFT        5
  58 #define BRCM_EG_TC_MASK         0x7
  59 #define BRCM_EG_PID_MASK        0x1f
  60
  61 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
  62 {
  63         struct dsa_slave_priv *p = netdev_priv(dev);
  64         u8 *brcm_tag;
  65
  66         if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
  67                 goto out_free;
  68
  69         skb_push(skb, BRCM_TAG_LEN);
  70
  71         memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
  72
  73         /* Build the tag after the MAC Source Address */
  74         brcm_tag = skb->data + 2 * ETH_ALEN;
  75
  76         /* Set the ingress opcode, traffic class, tag enforcment is
  77          * deprecated
  78          */
  79         brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
  80                         ((skb->priority << BRCM_IG_TC_SHIFT) & BRCM_IG_TC_MASK);
  81         brcm_tag[1] = 0;
  82         brcm_tag[2] = 0;
  83         if (p->port == 8)
  84                 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
  85         brcm_tag[3] = (1 << p->port) & BRCM_IG_DSTMAP1_MASK;
  86
  87         return skb;
  88
  89 out_free:
  90         kfree_skb(skb);
  91         return NULL;
  92 }
  93
  94 static int brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
  95                         struct packet_type *pt, struct net_device *orig_dev)
  96 {
  97         struct dsa_switch_tree *dst = dev->dsa_ptr;
  98         struct dsa_switch *ds;
  99         int source_port;
 100         u8 *brcm_tag;
 101
 102         if (unlikely(dst == NULL))
 103                 goto out_drop;
 104
 105         ds = dst->ds[0];
 106
 107         skb = skb_unshare(skb, GFP_ATOMIC);
 108         if (skb == NULL)
 109                 goto out;
 110
 111         if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 112                 goto out_drop;
 113
 114         /* skb->data points to the EtherType, the tag is right before it */
 115         brcm_tag = skb->data - 2;
 116
 117         /* The opcode should never be different than 0b000 */
 118         if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 119                 goto out_drop;
 120
 121         /* We should never see a reserved reason code without knowing how to
 122          * handle it
 123          */
 124         WARN_ON(brcm_tag[2] & BRCM_EG_RC_RSVD);
 125
 126         /* Locate which port this is coming from */
 127         source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 128
 129         /* Validate port against switch setup, either the port is totally */
 130         if (source_port >= DSA_MAX_PORTS || !ds->ports[source_port].netdev)
 131                 goto out_drop;
 132
 133         /* Remove Broadcom tag and update checksum */
 134         skb_pull_rcsum(skb, BRCM_TAG_LEN);
 135
 136         /* Move the Ethernet DA and SA */
 137         memmove(skb->data - ETH_HLEN,
 138                 skb->data - ETH_HLEN - BRCM_TAG_LEN,
 139                 2 * ETH_ALEN);
 140
 141         skb_push(skb, ETH_HLEN);
 142         skb->pkt_type = PACKET_HOST;
 143         skb->dev = ds->ports[source_port].netdev;
 144         skb->protocol = eth_type_trans(skb, skb->dev);
 145
 146         skb->dev->stats.rx_packets++;
 147         skb->dev->stats.rx_bytes += skb->len;
 148
 149         netif_receive_skb(skb);
 150
 151         return 0;
 152
 153 out_drop:
 154         kfree_skb(skb);
 155 out:
 156         return 0;
 157 }
 158
 159 const struct dsa_device_ops brcm_netdev_ops = {
 160         .xmit   = brcm_tag_xmit,
 161         .rcv    = brcm_tag_rcv,
 162 };