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Linux/net/dsa/tag_brcm.c

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  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 };
172 

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