net/dsa/tag_ksz.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * net/dsa/tag_ksz.c - Microchip KSZ Switch tag format handling
   4  * Copyright (c) 2017 Microchip Technology
   5  */
   6
   7 #include <linux/etherdevice.h>
   8 #include <linux/list.h>
   9 #include <linux/slab.h>
  10 #include <net/dsa.h>
  11 #include "dsa_priv.h"
  12
  13 /* Typically only one byte is used for tail tag. */
  14 #define KSZ_EGRESS_TAG_LEN              1
  15 #define KSZ_INGRESS_TAG_LEN             1
  16
  17 static struct sk_buff *ksz_common_xmit(struct sk_buff *skb,
  18                                        struct net_device *dev, int len)
  19 {
  20         struct sk_buff *nskb;
  21         int padlen;
  22
  23         padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
  24
  25         if (skb_tailroom(skb) >= padlen + len) {
  26                 /* Let dsa_slave_xmit() free skb */
  27                 if (__skb_put_padto(skb, skb->len + padlen, false))
  28                         return NULL;
  29
  30                 nskb = skb;
  31         } else {
  32                 nskb = alloc_skb(NET_IP_ALIGN + skb->len +
  33                                  padlen + len, GFP_ATOMIC);
  34                 if (!nskb)
  35                         return NULL;
  36                 skb_reserve(nskb, NET_IP_ALIGN);
  37
  38                 skb_reset_mac_header(nskb);
  39                 skb_set_network_header(nskb,
  40                                        skb_network_header(skb) - skb->head);
  41                 skb_set_transport_header(nskb,
  42                                          skb_transport_header(skb) - skb->head);
  43                 skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
  44
  45                 /* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free
  46                  * skb
  47                  */
  48                 if (skb_put_padto(nskb, nskb->len + padlen))
  49                         return NULL;
  50
  51                 consume_skb(skb);
  52         }
  53
  54         return nskb;
  55 }
  56
  57 static struct sk_buff *ksz_common_rcv(struct sk_buff *skb,
  58                                       struct net_device *dev,
  59                                       unsigned int port, unsigned int len)
  60 {
  61         skb->dev = dsa_master_find_slave(dev, 0, port);
  62         if (!skb->dev)
  63                 return NULL;
  64
  65         pskb_trim_rcsum(skb, skb->len - len);
  66
  67         skb->offload_fwd_mark = true;
  68
  69         return skb;
  70 }
  71
  72 /*
  73  * For Ingress (Host -> KSZ9477), 2 bytes are added before FCS.
  74  * ---------------------------------------------------------------------------
  75  * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|tag1(1byte)|FCS(4bytes)
  76  * ---------------------------------------------------------------------------
  77  * tag0 : Prioritization (not used now)
  78  * tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
  79  *
  80  * For Egress (KSZ9477 -> Host), 1 byte is added before FCS.
  81  * ---------------------------------------------------------------------------
  82  * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
  83  * ---------------------------------------------------------------------------
  84  * tag0 : zero-based value represents port
  85  *        (eg, 0x00=port1, 0x02=port3, 0x06=port7)
  86  */
  87
  88 #define KSZ9477_INGRESS_TAG_LEN         2
  89 #define KSZ9477_PTP_TAG_LEN             4
  90 #define KSZ9477_PTP_TAG_INDICATION      0x80
  91
  92 #define KSZ9477_TAIL_TAG_OVERRIDE       BIT(9)
  93 #define KSZ9477_TAIL_TAG_LOOKUP         BIT(10)
  94
  95 static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
  96                                     struct net_device *dev)
  97 {
  98         struct dsa_port *dp = dsa_slave_to_port(dev);
  99         struct sk_buff *nskb;
 100         u16 *tag;
 101         u8 *addr;
 102
 103         nskb = ksz_common_xmit(skb, dev, KSZ9477_INGRESS_TAG_LEN);
 104         if (!nskb)
 105                 return NULL;
 106
 107         /* Tag encoding */
 108         tag = skb_put(nskb, KSZ9477_INGRESS_TAG_LEN);
 109         addr = skb_mac_header(nskb);
 110
 111         *tag = BIT(dp->index);
 112
 113         if (is_link_local_ether_addr(addr))
 114                 *tag |= KSZ9477_TAIL_TAG_OVERRIDE;
 115
 116         *tag = cpu_to_be16(*tag);
 117
 118         return nskb;
 119 }
 120
 121 static struct sk_buff *ksz9477_rcv(struct sk_buff *skb, struct net_device *dev,
 122                                    struct packet_type *pt)
 123 {
 124         /* Tag decoding */
 125         u8 *tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;
 126         unsigned int port = tag[0] & 7;
 127         unsigned int len = KSZ_EGRESS_TAG_LEN;
 128
 129         /* Extra 4-bytes PTP timestamp */
 130         if (tag[0] & KSZ9477_PTP_TAG_INDICATION)
 131                 len += KSZ9477_PTP_TAG_LEN;
 132
 133         return ksz_common_rcv(skb, dev, port, len);
 134 }
 135
 136 const struct dsa_device_ops ksz9477_netdev_ops = {
 137         .name   = "ksz9477",
 138         .xmit   = ksz9477_xmit,
 139         .rcv    = ksz9477_rcv,
 140         .overhead = KSZ9477_INGRESS_TAG_LEN,
 141 };
 142
 143 #define KSZ9893_TAIL_TAG_OVERRIDE       BIT(5)
 144 #define KSZ9893_TAIL_TAG_LOOKUP         BIT(6)
 145
 146 static struct sk_buff *ksz9893_xmit(struct sk_buff *skb,
 147                                     struct net_device *dev)
 148 {
 149         struct dsa_port *dp = dsa_slave_to_port(dev);
 150         struct sk_buff *nskb;
 151         u8 *addr;
 152         u8 *tag;
 153
 154         nskb = ksz_common_xmit(skb, dev, KSZ_INGRESS_TAG_LEN);
 155         if (!nskb)
 156                 return NULL;
 157
 158         /* Tag encoding */
 159         tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
 160         addr = skb_mac_header(nskb);
 161
 162         *tag = BIT(dp->index);
 163
 164         if (is_link_local_ether_addr(addr))
 165                 *tag |= KSZ9893_TAIL_TAG_OVERRIDE;
 166
 167         return nskb;
 168 }
 169
 170 const struct dsa_device_ops ksz9893_netdev_ops = {
 171         .name   = "ksz9893",
 172         .xmit   = ksz9893_xmit,
 173         .rcv    = ksz9477_rcv,
 174         .overhead = KSZ_INGRESS_TAG_LEN,
 175 };