net/dsa/tag_qca.c

   1 /*
   2  * Copyright (c) 2015, The Linux Foundation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 and
   6  * only version 2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/etherdevice.h>
  15 #include "dsa_priv.h"
  16
  17 #define QCA_HDR_LEN     2
  18 #define QCA_HDR_VERSION 0x2
  19
  20 #define QCA_HDR_RECV_VERSION_MASK       GENMASK(15, 14)
  21 #define QCA_HDR_RECV_VERSION_S          14
  22 #define QCA_HDR_RECV_PRIORITY_MASK      GENMASK(13, 11)
  23 #define QCA_HDR_RECV_PRIORITY_S         11
  24 #define QCA_HDR_RECV_TYPE_MASK          GENMASK(10, 6)
  25 #define QCA_HDR_RECV_TYPE_S             6
  26 #define QCA_HDR_RECV_FRAME_IS_TAGGED    BIT(3)
  27 #define QCA_HDR_RECV_SOURCE_PORT_MASK   GENMASK(2, 0)
  28
  29 #define QCA_HDR_XMIT_VERSION_MASK       GENMASK(15, 14)
  30 #define QCA_HDR_XMIT_VERSION_S          14
  31 #define QCA_HDR_XMIT_PRIORITY_MASK      GENMASK(13, 11)
  32 #define QCA_HDR_XMIT_PRIORITY_S         11
  33 #define QCA_HDR_XMIT_CONTROL_MASK       GENMASK(10, 8)
  34 #define QCA_HDR_XMIT_CONTROL_S          8
  35 #define QCA_HDR_XMIT_FROM_CPU           BIT(7)
  36 #define QCA_HDR_XMIT_DP_BIT_MASK        GENMASK(6, 0)
  37
  38 static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
  39 {
  40         struct dsa_slave_priv *p = netdev_priv(dev);
  41         u16 *phdr, hdr;
  42
  43         dev->stats.tx_packets++;
  44         dev->stats.tx_bytes += skb->len;
  45
  46         if (skb_cow_head(skb, 0) < 0)
  47                 goto out_free;
  48
  49         skb_push(skb, QCA_HDR_LEN);
  50
  51         memmove(skb->data, skb->data + QCA_HDR_LEN, 2 * ETH_ALEN);
  52         phdr = (u16 *)(skb->data + 2 * ETH_ALEN);
  53
  54         /* Set the version field, and set destination port information */
  55         hdr = QCA_HDR_VERSION << QCA_HDR_XMIT_VERSION_S |
  56                 QCA_HDR_XMIT_FROM_CPU |
  57                 BIT(p->port);
  58
  59         *phdr = htons(hdr);
  60
  61         return skb;
  62
  63 out_free:
  64         kfree_skb(skb);
  65         return NULL;
  66 }
  67
  68 static int qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
  69                        struct packet_type *pt, struct net_device *orig_dev)
  70 {
  71         struct dsa_switch_tree *dst = dev->dsa_ptr;
  72         struct dsa_switch *ds;
  73         u8 ver;
  74         int port;
  75         __be16 *phdr, hdr;
  76
  77         if (unlikely(!dst))
  78                 goto out_drop;
  79
  80         skb = skb_unshare(skb, GFP_ATOMIC);
  81         if (!skb)
  82                 goto out;
  83
  84         if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
  85                 goto out_drop;
  86
  87         /* The QCA header is added by the switch between src addr and Ethertype
  88          * At this point, skb->data points to ethertype so header should be
  89          * right before
  90          */
  91         phdr = (__be16 *)(skb->data - 2);
  92         hdr = ntohs(*phdr);
  93
  94         /* Make sure the version is correct */
  95         ver = (hdr & QCA_HDR_RECV_VERSION_MASK) >> QCA_HDR_RECV_VERSION_S;
  96         if (unlikely(ver != QCA_HDR_VERSION))
  97                 goto out_drop;
  98
  99         /* Remove QCA tag and recalculate checksum */
 100         skb_pull_rcsum(skb, QCA_HDR_LEN);
 101         memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - QCA_HDR_LEN,
 102                 ETH_HLEN - QCA_HDR_LEN);
 103
 104         /* This protocol doesn't support cascading multiple switches so it's
 105          * safe to assume the switch is first in the tree
 106          */
 107         ds = dst->ds[0];
 108         if (!ds)
 109                 goto out_drop;
 110
 111         /* Get source port information */
 112         port = (hdr & QCA_HDR_RECV_SOURCE_PORT_MASK);
 113         if (!ds->ports[port].netdev)
 114                 goto out_drop;
 115
 116         /* Update skb & forward the frame accordingly */
 117         skb_push(skb, ETH_HLEN);
 118         skb->pkt_type = PACKET_HOST;
 119         skb->dev = ds->ports[port].netdev;
 120         skb->protocol = eth_type_trans(skb, skb->dev);
 121
 122         skb->dev->stats.rx_packets++;
 123         skb->dev->stats.rx_bytes += skb->len;
 124
 125         netif_receive_skb(skb);
 126
 127         return 0;
 128
 129 out_drop:
 130         kfree_skb(skb);
 131 out:
 132         return 0;
 133 }
 134
 135 const struct dsa_device_ops qca_netdev_ops = {
 136         .xmit   = qca_tag_xmit,
 137         .rcv    = qca_tag_rcv,
 138 };