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
  16 #include "dsa_priv.h"
  17
  18 #define QCA_HDR_LEN     2
  19 #define QCA_HDR_VERSION 0x2
  20
  21 #define QCA_HDR_RECV_VERSION_MASK       GENMASK(15, 14)
  22 #define QCA_HDR_RECV_VERSION_S          14
  23 #define QCA_HDR_RECV_PRIORITY_MASK      GENMASK(13, 11)
  24 #define QCA_HDR_RECV_PRIORITY_S         11
  25 #define QCA_HDR_RECV_TYPE_MASK          GENMASK(10, 6)
  26 #define QCA_HDR_RECV_TYPE_S             6
  27 #define QCA_HDR_RECV_FRAME_IS_TAGGED    BIT(3)
  28 #define QCA_HDR_RECV_SOURCE_PORT_MASK   GENMASK(2, 0)
  29
  30 #define QCA_HDR_XMIT_VERSION_MASK       GENMASK(15, 14)
  31 #define QCA_HDR_XMIT_VERSION_S          14
  32 #define QCA_HDR_XMIT_PRIORITY_MASK      GENMASK(13, 11)
  33 #define QCA_HDR_XMIT_PRIORITY_S         11
  34 #define QCA_HDR_XMIT_CONTROL_MASK       GENMASK(10, 8)
  35 #define QCA_HDR_XMIT_CONTROL_S          8
  36 #define QCA_HDR_XMIT_FROM_CPU           BIT(7)
  37 #define QCA_HDR_XMIT_DP_BIT_MASK        GENMASK(6, 0)
  38
  39 static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
  40 {
  41         struct dsa_slave_priv *p = netdev_priv(dev);
  42         u16 *phdr, hdr;
  43
  44         dev->stats.tx_packets++;
  45         dev->stats.tx_bytes += skb->len;
  46
  47         if (skb_cow_head(skb, 0) < 0)
  48                 return NULL;
  49
  50         skb_push(skb, QCA_HDR_LEN);
  51
  52         memmove(skb->data, skb->data + QCA_HDR_LEN, 2 * ETH_ALEN);
  53         phdr = (u16 *)(skb->data + 2 * ETH_ALEN);
  54
  55         /* Set the version field, and set destination port information */
  56         hdr = QCA_HDR_VERSION << QCA_HDR_XMIT_VERSION_S |
  57                 QCA_HDR_XMIT_FROM_CPU |
  58                 BIT(p->dp->index);
  59
  60         *phdr = htons(hdr);
  61
  62         return skb;
  63 }
  64
  65 static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
  66                                    struct packet_type *pt)
  67 {
  68         struct dsa_switch_tree *dst = dev->dsa_ptr;
  69         struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
  70         struct dsa_switch *ds;
  71         u8 ver;
  72         int port;
  73         __be16 *phdr, hdr;
  74
  75         if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
  76                 return NULL;
  77
  78         /* The QCA header is added by the switch between src addr and Ethertype
  79          * At this point, skb->data points to ethertype so header should be
  80          * right before
  81          */
  82         phdr = (__be16 *)(skb->data - 2);
  83         hdr = ntohs(*phdr);
  84
  85         /* Make sure the version is correct */
  86         ver = (hdr & QCA_HDR_RECV_VERSION_MASK) >> QCA_HDR_RECV_VERSION_S;
  87         if (unlikely(ver != QCA_HDR_VERSION))
  88                 return NULL;
  89
  90         /* Remove QCA tag and recalculate checksum */
  91         skb_pull_rcsum(skb, QCA_HDR_LEN);
  92         memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - QCA_HDR_LEN,
  93                 ETH_HLEN - QCA_HDR_LEN);
  94
  95         /* This protocol doesn't support cascading multiple switches so it's
  96          * safe to assume the switch is first in the tree
  97          */
  98         ds = cpu_dp->ds;
  99         if (!ds)
 100                 return NULL;
 101
 102         /* Get source port information */
 103         port = (hdr & QCA_HDR_RECV_SOURCE_PORT_MASK);
 104         if (!ds->ports[port].netdev)
 105                 return NULL;
 106
 107         /* Update skb & forward the frame accordingly */
 108         skb->dev = ds->ports[port].netdev;
 109
 110         return skb;
 111 }
 112
 113 const struct dsa_device_ops qca_netdev_ops = {
 114         .xmit   = qca_tag_xmit,
 115         .rcv    = qca_tag_rcv,
 116 };