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
  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
  62 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev)
  63 {
  64         struct dsa_slave_priv *p = netdev_priv(dev);
  65         u8 *brcm_tag;
  66
  67         if (skb_cow_head(skb, BRCM_TAG_LEN) < 0)
  68                 return NULL;
  69
  70         skb_push(skb, BRCM_TAG_LEN);
  71
  72         memmove(skb->data, skb->data + BRCM_TAG_LEN, 2 * ETH_ALEN);
  73
  74         /* Build the tag after the MAC Source Address */
  75         brcm_tag = skb->data + 2 * ETH_ALEN;
  76
  77         /* Set the ingress opcode, traffic class, tag enforcment is
  78          * deprecated
  79          */
  80         brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
  81                         ((skb->priority << BRCM_IG_TC_SHIFT) & BRCM_IG_TC_MASK);
  82         brcm_tag[1] = 0;
  83         brcm_tag[2] = 0;
  84         if (p->dp->index == 8)
  85                 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
  86         brcm_tag[3] = (1 << p->dp->index) & BRCM_IG_DSTMAP1_MASK;
  87
  88         return skb;
  89 }
  90
  91 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
  92                                     struct packet_type *pt,
  93                                     struct net_device *orig_dev)
  94 {
  95         struct dsa_switch_tree *dst = dev->dsa_ptr;
  96         struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
  97         struct dsa_switch *ds = cpu_dp->ds;
  98         int source_port;
  99         u8 *brcm_tag;
 100
 101         if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
 102                 return NULL;
 103
 104         /* skb->data points to the EtherType, the tag is right before it */
 105         brcm_tag = skb->data - 2;
 106
 107         /* The opcode should never be different than 0b000 */
 108         if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
 109                 return NULL;
 110
 111         /* We should never see a reserved reason code without knowing how to
 112          * handle it
 113          */
 114         if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
 115                 return NULL;
 116
 117         /* Locate which port this is coming from */
 118         source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 119
 120         /* Validate port against switch setup, either the port is totally */
 121         if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
 122                 return NULL;
 123
 124         /* Remove Broadcom tag and update checksum */
 125         skb_pull_rcsum(skb, BRCM_TAG_LEN);
 126
 127         /* Move the Ethernet DA and SA */
 128         memmove(skb->data - ETH_HLEN,
 129                 skb->data - ETH_HLEN - BRCM_TAG_LEN,
 130                 2 * ETH_ALEN);
 131
 132         skb->dev = ds->ports[source_port].netdev;
 133
 134         return skb;
 135 }
 136
 137 const struct dsa_device_ops brcm_netdev_ops = {
 138         .xmit   = brcm_tag_xmit,
 139         .rcv    = brcm_tag_rcv,
 140 };