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 netdev_tx_t 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         dev->stats.tx_packets++;
  67         dev->stats.tx_bytes += skb->len;
  68
  69         if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
  70                 goto out_free;
  71
  72         skb_push(skb, BRCM_TAG_LEN);
  73
  74         memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
  75
  76         /* Build the tag after the MAC Source Address */
  77         brcm_tag = skb->data + 2 * ETH_ALEN;
  78
  79         /* Set the ingress opcode, traffic class, tag enforcment is
  80          * deprecated
  81          */
  82         brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
  83                         ((skb->priority << BRCM_IG_TC_SHIFT) & BRCM_IG_TC_MASK);
  84         brcm_tag[1] = 0;
  85         brcm_tag[2] = 0;
  86         if (p->port == 8)
  87                 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
  88         brcm_tag[3] = (1 << p->port) & BRCM_IG_DSTMAP1_MASK;
  89
  90         /* Queue the SKB for transmission on the parent interface, but
  91          * do not modify its EtherType
  92          */
  93         skb->dev = p->parent->dst->master_netdev;
  94         dev_queue_xmit(skb);
  95
  96         return NETDEV_TX_OK;
  97
  98 out_free:
  99         kfree_skb(skb);
 100         return NETDEV_TX_OK;
 101 }
 102
 103 static int brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 104                         struct packet_type *pt, struct net_device *orig_dev)
 105 {
 106         struct dsa_switch_tree *dst = dev->dsa_ptr;
 107         struct dsa_switch *ds;
 108         int source_port;
 109         u8 *brcm_tag;
 110
 111         if (unlikely(dst == NULL))
 112                 goto out_drop;
 113
 114         ds = dst->ds[0];
 115
 116         skb = skb_unshare(skb, GFP_ATOMIC);
 117         if (skb == NULL)
 118                 goto out;
 119
 120         if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 121                 goto out_drop;
 122
 123         /* skb->data points to the EtherType, the tag is right before it */
 124         brcm_tag = skb->data - 2;
 125
 126         /* The opcode should never be different than 0b000 */
 127         if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 128                 goto out_drop;
 129
 130         /* We should never see a reserved reason code without knowing how to
 131          * handle it
 132          */
 133         WARN_ON(brcm_tag[2] & BRCM_EG_RC_RSVD);
 134
 135         /* Locate which port this is coming from */
 136         source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 137
 138         /* Validate port against switch setup, either the port is totally */
 139         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
 140                 goto out_drop;
 141
 142         /* Remove Broadcom tag and update checksum */
 143         skb_pull_rcsum(skb, BRCM_TAG_LEN);
 144
 145         /* Move the Ethernet DA and SA */
 146         memmove(skb->data - ETH_HLEN,
 147                 skb->data - ETH_HLEN - BRCM_TAG_LEN,
 148                 2 * ETH_ALEN);
 149
 150         skb_push(skb, ETH_HLEN);
 151         skb->pkt_type = PACKET_HOST;
 152         skb->dev = ds->ports[source_port];
 153         skb->protocol = eth_type_trans(skb, skb->dev);
 154
 155         skb->dev->stats.rx_packets++;
 156         skb->dev->stats.rx_bytes += skb->len;
 157
 158         netif_receive_skb(skb);
 159
 160         return 0;
 161
 162 out_drop:
 163         kfree_skb(skb);
 164 out:
 165         return 0;
 166 }
 167
 168 const struct dsa_device_ops brcm_netdev_ops = {
 169         .xmit   = brcm_tag_xmit,
 170         .rcv    = brcm_tag_rcv,
 171 };