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   1 From c2ee8181fddb293d296477f60b3eb4fa3ce4e1a6 Mon Sep 17 00:00:00 2001
   2 From: Ansuel Smith <ansuelsmth@gmail.com>
   3 Date: Wed, 2 Feb 2022 01:03:25 +0100
   4 Subject: [PATCH 06/16] net: dsa: tag_qca: add define for handling mgmt
   5  Ethernet packet
   6
   7 Add all the required define to prepare support for mgmt read/write in
   8 Ethernet packet. Any packet of this type has to be dropped as the only
   9 use of these special packet is receive ack for an mgmt write request or
  10 receive data for an mgmt read request.
  11 A struct is used that emulates the Ethernet header but is used for a
  12 different purpose.
  13
  14 Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
  15 Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
  16 Signed-off-by: David S. Miller <davem@davemloft.net>
  17 ---
  18  include/linux/dsa/tag_qca.h | 44 +++++++++++++++++++++++++++++++++++++
  19  net/dsa/tag_qca.c           | 15 ++++++++++---
  20  2 files changed, 56 insertions(+), 3 deletions(-)
  21
  22 --- a/include/linux/dsa/tag_qca.h
  23 +++ b/include/linux/dsa/tag_qca.h
  24 @@ -12,10 +12,54 @@
  25  #define QCA_HDR_RECV_FRAME_IS_TAGGED   BIT(3)
  26  #define QCA_HDR_RECV_SOURCE_PORT       GENMASK(2, 0)
  27
  28 +/* Packet type for recv */
  29 +#define QCA_HDR_RECV_TYPE_NORMAL       0x0
  30 +#define QCA_HDR_RECV_TYPE_MIB          0x1
  31 +#define QCA_HDR_RECV_TYPE_RW_REG_ACK   0x2
  32 +
  33  #define QCA_HDR_XMIT_VERSION           GENMASK(15, 14)
  34  #define QCA_HDR_XMIT_PRIORITY          GENMASK(13, 11)
  35  #define QCA_HDR_XMIT_CONTROL           GENMASK(10, 8)
  36  #define QCA_HDR_XMIT_FROM_CPU          BIT(7)
  37  #define QCA_HDR_XMIT_DP_BIT            GENMASK(6, 0)
  38
  39 +/* Packet type for xmit */
  40 +#define QCA_HDR_XMIT_TYPE_NORMAL       0x0
  41 +#define QCA_HDR_XMIT_TYPE_RW_REG       0x1
  42 +
  43 +/* Check code for a valid mgmt packet. Switch will ignore the packet
  44 + * with this wrong.
  45 + */
  46 +#define QCA_HDR_MGMT_CHECK_CODE_VAL    0x5
  47 +
  48 +/* Specific define for in-band MDIO read/write with Ethernet packet */
  49 +#define QCA_HDR_MGMT_SEQ_LEN           4 /* 4 byte for the seq */
  50 +#define QCA_HDR_MGMT_COMMAND_LEN       4 /* 4 byte for the command */
  51 +#define QCA_HDR_MGMT_DATA1_LEN         4 /* First 4 byte for the mdio data */
  52 +#define QCA_HDR_MGMT_HEADER_LEN                (QCA_HDR_MGMT_SEQ_LEN + \
  53 +                                       QCA_HDR_MGMT_COMMAND_LEN + \
  54 +                                       QCA_HDR_MGMT_DATA1_LEN)
  55 +
  56 +#define QCA_HDR_MGMT_DATA2_LEN         12 /* Other 12 byte for the mdio data */
  57 +#define QCA_HDR_MGMT_PADDING_LEN       34 /* Padding to reach the min Ethernet packet */
  58 +
  59 +#define QCA_HDR_MGMT_PKT_LEN           (QCA_HDR_MGMT_HEADER_LEN + \
  60 +                                       QCA_HDR_LEN + \
  61 +                                       QCA_HDR_MGMT_DATA2_LEN + \
  62 +                                       QCA_HDR_MGMT_PADDING_LEN)
  63 +
  64 +#define QCA_HDR_MGMT_SEQ_NUM           GENMASK(31, 0)  /* 63, 32 */
  65 +#define QCA_HDR_MGMT_CHECK_CODE                GENMASK(31, 29) /* 31, 29 */
  66 +#define QCA_HDR_MGMT_CMD               BIT(28)         /* 28 */
  67 +#define QCA_HDR_MGMT_LENGTH            GENMASK(23, 20) /* 23, 20 */
  68 +#define QCA_HDR_MGMT_ADDR              GENMASK(18, 0)  /* 18, 0 */
  69 +
  70 +/* Special struct emulating a Ethernet header */
  71 +struct qca_mgmt_ethhdr {
  72 +       u32 command;            /* command bit 31:0 */
  73 +       u32 seq;                /* seq 63:32 */
  74 +       u32 mdio_data;          /* first 4byte mdio */
  75 +       __be16 hdr;             /* qca hdr */
  76 +} __packed;
  77 +
  78  #endif /* __TAG_QCA_H */
  79 --- a/net/dsa/tag_qca.c
  80 +++ b/net/dsa/tag_qca.c
  81 @@ -32,10 +32,12 @@ static struct sk_buff *qca_tag_xmit(stru
  82
  83  static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev)
  84  {
  85 -       u8 ver;
  86 -       u16  hdr;
  87 -       int port;
  88 +       u8 ver, pk_type;
  89         __be16 *phdr;
  90 +       int port;
  91 +       u16 hdr;
  92 +
  93 +       BUILD_BUG_ON(sizeof(struct qca_mgmt_ethhdr) != QCA_HDR_MGMT_HEADER_LEN + QCA_HDR_LEN);
  94
  95         if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
  96                 return NULL;
  97 @@ -48,6 +50,13 @@ static struct sk_buff *qca_tag_rcv(struc
  98         if (unlikely(ver != QCA_HDR_VERSION))
  99                 return NULL;
 100
 101 +       /* Get pk type */
 102 +       pk_type = FIELD_GET(QCA_HDR_RECV_TYPE, hdr);
 103 +
 104 +       /* Ethernet MDIO read/write packet */
 105 +       if (pk_type == QCA_HDR_RECV_TYPE_RW_REG_ACK)
 106 +               return NULL;
 107 +
 108         /* Remove QCA tag and recalculate checksum */
 109         skb_pull_rcsum(skb, QCA_HDR_LEN);
 110         dsa_strip_etype_header(skb, QCA_HDR_LEN);