net/dsa/tag_ar9331.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2019 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
   4  */
   5
   6
   7 #include <linux/bitfield.h>
   8 #include <linux/etherdevice.h>
   9
  10 #include "tag.h"
  11
  12 #define AR9331_NAME                     "ar9331"
  13
  14 #define AR9331_HDR_LEN                  2
  15 #define AR9331_HDR_VERSION              1
  16
  17 #define AR9331_HDR_VERSION_MASK         GENMASK(15, 14)
  18 #define AR9331_HDR_PRIORITY_MASK        GENMASK(13, 12)
  19 #define AR9331_HDR_TYPE_MASK            GENMASK(10, 8)
  20 #define AR9331_HDR_BROADCAST            BIT(7)
  21 #define AR9331_HDR_FROM_CPU             BIT(6)
  22 /* AR9331_HDR_RESERVED - not used or may be version field.
  23  * According to the AR8216 doc it should 0b10. On AR9331 it is 0b11 on RX path
  24  * and should be set to 0b11 to make it work.
  25  */
  26 #define AR9331_HDR_RESERVED_MASK        GENMASK(5, 4)
  27 #define AR9331_HDR_PORT_NUM_MASK        GENMASK(3, 0)
  28
  29 static struct sk_buff *ar9331_tag_xmit(struct sk_buff *skb,
  30                                        struct net_device *dev)
  31 {
  32         struct dsa_port *dp = dsa_slave_to_port(dev);
  33         __le16 *phdr;
  34         u16 hdr;
  35
  36         phdr = skb_push(skb, AR9331_HDR_LEN);
  37
  38         hdr = FIELD_PREP(AR9331_HDR_VERSION_MASK, AR9331_HDR_VERSION);
  39         hdr |= AR9331_HDR_FROM_CPU | dp->index;
  40         /* 0b10 for AR8216 and 0b11 for AR9331 */
  41         hdr |= AR9331_HDR_RESERVED_MASK;
  42
  43         phdr[0] = cpu_to_le16(hdr);
  44
  45         return skb;
  46 }
  47
  48 static struct sk_buff *ar9331_tag_rcv(struct sk_buff *skb,
  49                                       struct net_device *ndev)
  50 {
  51         u8 ver, port;
  52         u16 hdr;
  53
  54         if (unlikely(!pskb_may_pull(skb, AR9331_HDR_LEN)))
  55                 return NULL;
  56
  57         hdr = le16_to_cpu(*(__le16 *)skb_mac_header(skb));
  58
  59         ver = FIELD_GET(AR9331_HDR_VERSION_MASK, hdr);
  60         if (unlikely(ver != AR9331_HDR_VERSION)) {
  61                 netdev_warn_once(ndev, "%s:%i wrong header version 0x%2x\n",
  62                                  __func__, __LINE__, hdr);
  63                 return NULL;
  64         }
  65
  66         if (unlikely(hdr & AR9331_HDR_FROM_CPU)) {
  67                 netdev_warn_once(ndev, "%s:%i packet should not be from cpu 0x%2x\n",
  68                                  __func__, __LINE__, hdr);
  69                 return NULL;
  70         }
  71
  72         skb_pull_rcsum(skb, AR9331_HDR_LEN);
  73
  74         /* Get source port information */
  75         port = FIELD_GET(AR9331_HDR_PORT_NUM_MASK, hdr);
  76
  77         skb->dev = dsa_master_find_slave(ndev, 0, port);
  78         if (!skb->dev)
  79                 return NULL;
  80
  81         return skb;
  82 }
  83
  84 static const struct dsa_device_ops ar9331_netdev_ops = {
  85         .name   = AR9331_NAME,
  86         .proto  = DSA_TAG_PROTO_AR9331,
  87         .xmit   = ar9331_tag_xmit,
  88         .rcv    = ar9331_tag_rcv,
  89         .needed_headroom = AR9331_HDR_LEN,
  90 };
  91
  92 MODULE_LICENSE("GPL v2");
  93 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_AR9331, AR9331_NAME);
  94 module_dsa_tag_driver(ar9331_netdev_ops);