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       1                 :            : /* SPDX-License-Identifier: MIT
       2                 :            :  * Google Virtual Ethernet (gve) driver
       3                 :            :  * Copyright (C) 2015-2022 Google, Inc.
       4                 :            :  */
       5                 :            : 
       6                 :            : /* GVE Transmit Descriptor formats */
       7                 :            : 
       8                 :            : #ifndef _GVE_DESC_H_
       9                 :            : #define _GVE_DESC_H_
      10                 :            : 
      11                 :            : #include "gve_osdep.h"
      12                 :            : 
      13                 :            : /* A note on seg_addrs
      14                 :            :  *
      15                 :            :  * Base addresses encoded in seg_addr are not assumed to be physical
      16                 :            :  * addresses. The ring format assumes these come from some linear address
      17                 :            :  * space. This could be physical memory, kernel virtual memory, user virtual
      18                 :            :  * memory.
      19                 :            :  * If raw dma addressing is not supported then gVNIC uses lists of registered
      20                 :            :  * pages. Each queue is assumed to be associated with a single such linear
      21                 :            :  * address space to ensure a consistent meaning for seg_addrs posted to its
      22                 :            :  * rings.
      23                 :            :  */
      24                 :            : 
      25                 :            : struct gve_tx_pkt_desc {
      26                 :            :         u8      type_flags;  /* desc type is lower 4 bits, flags upper */
      27                 :            :         u8      l4_csum_offset;  /* relative offset of L4 csum word */
      28                 :            :         u8      l4_hdr_offset;  /* Offset of start of L4 headers in packet */
      29                 :            :         u8      desc_cnt;  /* Total descriptors for this packet */
      30                 :            :         __be16  len;  /* Total length of this packet (in bytes) */
      31                 :            :         __be16  seg_len;  /* Length of this descriptor's segment */
      32                 :            :         __be64  seg_addr;  /* Base address (see note) of this segment */
      33                 :            : } __packed;
      34                 :            : 
      35                 :            : struct gve_tx_mtd_desc {
      36                 :            :         u8      type_flags;     /* type is lower 4 bits, subtype upper  */
      37                 :            :         u8      path_state;     /* state is lower 4 bits, hash type upper */
      38                 :            :         __be16  reserved0;
      39                 :            :         __be32  path_hash;
      40                 :            :         __be64  reserved1;
      41                 :            : } __packed;
      42                 :            : 
      43                 :            : struct gve_tx_seg_desc {
      44                 :            :         u8      type_flags;     /* type is lower 4 bits, flags upper    */
      45                 :            :         u8      l3_offset;      /* TSO: 2 byte units to start of IPH    */
      46                 :            :         __be16  reserved;
      47                 :            :         __be16  mss;            /* TSO MSS                              */
      48                 :            :         __be16  seg_len;
      49                 :            :         __be64  seg_addr;
      50                 :            : } __packed;
      51                 :            : 
      52                 :            : /* GVE Transmit Descriptor Types */
      53                 :            : #define GVE_TXD_STD             (0x0 << 4) /* Std with Host Address       */
      54                 :            : #define GVE_TXD_TSO             (0x1 << 4) /* TSO with Host Address       */
      55                 :            : #define GVE_TXD_SEG             (0x2 << 4) /* Seg with Host Address       */
      56                 :            : #define GVE_TXD_MTD             (0x3 << 4) /* Metadata                    */
      57                 :            : 
      58                 :            : /* GVE Transmit Descriptor Flags for Std Pkts */
      59                 :            : #define GVE_TXF_L4CSUM  BIT(0)  /* Need csum offload */
      60                 :            : #define GVE_TXF_TSTAMP  BIT(2)  /* Timestamp required */
      61                 :            : 
      62                 :            : /* GVE Transmit Descriptor Flags for TSO Segs */
      63                 :            : #define GVE_TXSF_IPV6   BIT(1)  /* IPv6 TSO */
      64                 :            : 
      65                 :            : /* GVE Transmit Descriptor Options for MTD Segs */
      66                 :            : #define GVE_MTD_SUBTYPE_PATH            0
      67                 :            : 
      68                 :            : #define GVE_MTD_PATH_STATE_DEFAULT      0
      69                 :            : #define GVE_MTD_PATH_STATE_TIMEOUT      1
      70                 :            : #define GVE_MTD_PATH_STATE_CONGESTION   2
      71                 :            : #define GVE_MTD_PATH_STATE_RETRANSMIT   3
      72                 :            : 
      73                 :            : #define GVE_MTD_PATH_HASH_NONE         (0x0 << 4)
      74                 :            : #define GVE_MTD_PATH_HASH_L4           (0x1 << 4)
      75                 :            : 
      76                 :            : /* GVE Receive Packet Descriptor */
      77                 :            : /* The start of an ethernet packet comes 2 bytes into the rx buffer.
      78                 :            :  * gVNIC adds this padding so that both the DMA and the L3/4 protocol header
      79                 :            :  * access is aligned.
      80                 :            :  */
      81                 :            : #define GVE_RX_PAD 2
      82                 :            : 
      83                 :            : struct gve_rx_desc {
      84                 :            :         u8      padding[48];
      85                 :            :         __be32  rss_hash;  /* Receive-side scaling hash (Toeplitz for gVNIC) */
      86                 :            :         __be16  mss;
      87                 :            :         __be16  reserved;  /* Reserved to zero */
      88                 :            :         u8      hdr_len;  /* Header length (L2-L4) including padding */
      89                 :            :         u8      hdr_off;  /* 64-byte-scaled offset into RX_DATA entry */
      90                 :            :         __sum16 csum;  /* 1's-complement partial checksum of L3+ bytes */
      91                 :            :         __be16  len;  /* Length of the received packet */
      92                 :            :         __be16  flags_seq;  /* Flags [15:3] and sequence number [2:0] (1-7) */
      93                 :            : } __packed;
      94                 :            : GVE_CHECK_STRUCT_LEN(64, gve_rx_desc);
      95                 :            : 
      96                 :            : /* If the device supports raw dma addressing then the addr in data slot is
      97                 :            :  * the dma address of the buffer.
      98                 :            :  * If the device only supports registered segments then the addr is a byte
      99                 :            :  * offset into the registered segment (an ordered list of pages) where the
     100                 :            :  * buffer is.
     101                 :            :  */
     102                 :            : union gve_rx_data_slot {
     103                 :            :         __be64 qpl_offset;
     104                 :            :         __be64 addr;
     105                 :            : };
     106                 :            : 
     107                 :            : /* GVE Receive Packet Descriptor Seq No */
     108                 :            : #define GVE_SEQNO(x) (be16_to_cpu(x) & 0x7)
     109                 :            : 
     110                 :            : /* GVE Receive Packet Descriptor Flags */
     111                 :            : #define GVE_RXFLG(x)    cpu_to_be16(1 << (3 + (x)))
     112                 :            : #define GVE_RXF_FRAG            GVE_RXFLG(3)    /* IP Fragment                  */
     113                 :            : #define GVE_RXF_IPV4            GVE_RXFLG(4)    /* IPv4                         */
     114                 :            : #define GVE_RXF_IPV6            GVE_RXFLG(5)    /* IPv6                         */
     115                 :            : #define GVE_RXF_TCP             GVE_RXFLG(6)    /* TCP Packet                   */
     116                 :            : #define GVE_RXF_UDP             GVE_RXFLG(7)    /* UDP Packet                   */
     117                 :            : #define GVE_RXF_ERR             GVE_RXFLG(8)    /* Packet Error Detected        */
     118                 :            : #define GVE_RXF_PKT_CONT        GVE_RXFLG(10)   /* Multi Fragment RX packet     */
     119                 :            : 
     120                 :            : /* GVE IRQ */
     121                 :            : #define GVE_IRQ_ACK     BIT(31)
     122                 :            : #define GVE_IRQ_MASK    BIT(30)
     123                 :            : #define GVE_IRQ_EVENT   BIT(29)
     124                 :            : 
     125                 :            : static inline bool gve_needs_rss(__be16 flag)
     126                 :            : {
     127         [ #  # ]:          0 :         if (flag & GVE_RXF_FRAG)
     128                 :            :                 return false;
     129         [ #  # ]:          0 :         if (flag & (GVE_RXF_IPV4 | GVE_RXF_IPV6))
     130                 :            :                 return true;
     131                 :            :         return false;
     132                 :            : }
     133                 :            : 
     134                 :            : static inline u8 gve_next_seqno(u8 seq)
     135                 :            : {
     136         [ #  # ]:          0 :         return (seq + 1) == 8 ? 1 : seq + 1;
     137                 :            : }
     138                 :            : #endif /* _GVE_DESC_H_ */