/* SPDX-License-Identifier: (GPL-2.0 OR MIT)
 * Google virtual Ethernet (gve) driver
 *
 * Copyright (C) 2015-2021 Google, Inc.
 */

/* GVE DQO Descriptor formats */

#ifndef _GVE_DESC_DQO_H_
#define _GVE_DESC_DQO_H_

#include <linux/build_bug.h>

#define GVE_TX_MAX_HDR_SIZE_DQO 255
#define GVE_TX_MIN_TSO_MSS_DQO 88

#ifndef __LITTLE_ENDIAN_BITFIELD
#error "Only little endian supported"
#endif

/* Basic TX descriptor (DTYPE 0x0C) */
struct gve_tx_pkt_desc_dqo {
        __le64 buf_addr;

        /* Must be GVE_TX_PKT_DESC_DTYPE_DQO (0xc) */
        u8 dtype: 5;

        /* Denotes the last descriptor of a packet. */
        u8 end_of_packet: 1;
        u8 checksum_offload_enable: 1;

        /* If set, will generate a descriptor completion for this descriptor. */
        u8 report_event: 1;
        u8 reserved0;
        __le16 reserved1;

        /* The TX completion associated with this packet will contain this tag.
         */
        __le16 compl_tag;
        u16 buf_size: 14;
        u16 reserved2: 2;
} __packed;
static_assert(sizeof(struct gve_tx_pkt_desc_dqo) == 16);

#define GVE_TX_PKT_DESC_DTYPE_DQO 0xc
#define GVE_TX_MAX_BUF_SIZE_DQO ((16 * 1024) - 1)

/* Maximum number of data descriptors allowed per packet, or per-TSO segment. */
#define GVE_TX_MAX_DATA_DESCS 10

/* Min gap between tail and head to avoid cacheline overlap */
#define GVE_TX_MIN_DESC_PREVENT_CACHE_OVERLAP 4

/* "report_event" on TX packet descriptors may only be reported on the last
 * descriptor of a TX packet, and they must be spaced apart with at least this
 * value.
 */
#define GVE_TX_MIN_RE_INTERVAL 32

struct gve_tx_context_cmd_dtype {
        u8 dtype: 5;
        u8 tso: 1;
        u8 reserved1: 2;

        u8 reserved2;
};

static_assert(sizeof(struct gve_tx_context_cmd_dtype) == 2);

/* TX Native TSO Context DTYPE (0x05)
 *
 * "flex" fields allow the driver to send additional packet context to HW.
 */
struct gve_tx_tso_context_desc_dqo {
        /* The L4 payload bytes that should be segmented. */
        u32 tso_total_len: 24;
        u32 flex10: 8;

        /* Max segment size in TSO excluding headers. */
        u16 mss: 14;
        u16 reserved: 2;

        u8 header_len; /* Header length to use for TSO offload */
        u8 flex11;
        struct gve_tx_context_cmd_dtype cmd_dtype;
        u8 flex0;
        u8 flex5;
        u8 flex6;
        u8 flex7;
        u8 flex8;
        u8 flex9;
} __packed;
static_assert(sizeof(struct gve_tx_tso_context_desc_dqo) == 16);

#define GVE_TX_TSO_CTX_DESC_DTYPE_DQO 0x5

/* General context descriptor for sending metadata. */
struct gve_tx_general_context_desc_dqo {
        u8 flex4;
        u8 flex5;
        u8 flex6;
        u8 flex7;
        u8 flex8;
        u8 flex9;
        u8 flex10;
        u8 flex11;
        struct gve_tx_context_cmd_dtype cmd_dtype;
        u16 reserved;
        u8 flex0;
        u8 flex1;
        u8 flex2;
        u8 flex3;
} __packed;
static_assert(sizeof(struct gve_tx_general_context_desc_dqo) == 16);

#define GVE_TX_GENERAL_CTX_DESC_DTYPE_DQO 0x4

/* Logical structure of metadata which is packed into context descriptor flex
 * fields.
 */
struct gve_tx_metadata_dqo {
        union {
                struct {
                        u8 version;

                        /* If `skb->l4_hash` is set, this value should be
                         * derived from `skb->hash`.
                         *
                         * A zero value means no l4_hash was associated with the
                         * skb.
                         */
                        u16 path_hash: 15;

                        /* Should be set to 1 if the flow associated with the
                         * skb had a rehash from the TCP stack.
                         */
                        u16 rehash_event: 1;
                }  __packed;
                u8 bytes[12];
        };
}  __packed;
static_assert(sizeof(struct gve_tx_metadata_dqo) == 12);

#define GVE_TX_METADATA_VERSION_DQO 0

/* TX completion descriptor */
struct gve_tx_compl_desc {
        /* For types 0-4 this is the TX queue ID associated with this
         * completion.
         */
        u16 id: 11;

        /* See: GVE_COMPL_TYPE_DQO* */
        u16 type: 3;
        u16 reserved0: 1;

        /* Flipped by HW to notify the descriptor is populated. */
        u16 generation: 1;
        union {
                /* For descriptor completions, this is the last index fetched
                 * by HW + 1.
                 */
                __le16 tx_head;

                /* For packet completions, this is the completion tag set on the
                 * TX packet descriptors.
                 */
                __le16 completion_tag;
        };
        __le32 reserved1;
} __packed;
static_assert(sizeof(struct gve_tx_compl_desc) == 8);

#define GVE_COMPL_TYPE_DQO_PKT 0x2 /* Packet completion */
#define GVE_COMPL_TYPE_DQO_DESC 0x4 /* Descriptor completion */
#define GVE_COMPL_TYPE_DQO_MISS 0x1 /* Miss path completion */
#define GVE_COMPL_TYPE_DQO_REINJECTION 0x3 /* Re-injection completion */

/* Descriptor to post buffers to HW on buffer queue. */
struct gve_rx_desc_dqo {
        __le16 buf_id; /* ID returned in Rx completion descriptor */
        __le16 reserved0;
        __le32 reserved1;
        __le64 buf_addr; /* DMA address of the buffer */
        __le64 header_buf_addr;
        __le64 reserved2;
} __packed;
static_assert(sizeof(struct gve_rx_desc_dqo) == 32);

/* Descriptor for HW to notify SW of new packets received on RX queue. */
struct gve_rx_compl_desc_dqo {
        /* Must be 1 */
        u8 rxdid: 4;
        u8 reserved0: 4;

        /* Packet originated from this system rather than the network. */
        u8 loopback: 1;
        /* Set when IPv6 packet contains a destination options header or routing
         * header.
         */
        u8 ipv6_ex_add: 1;
        /* Invalid packet was received. */
        u8 rx_error: 1;
        u8 reserved1: 5;

        u16 packet_type: 10;
        u16 ip_hdr_err: 1;
        u16 udp_len_err: 1;
        u16 raw_cs_invalid: 1;
        u16 reserved2: 3;

        u16 packet_len: 14;
        /* Flipped by HW to notify the descriptor is populated. */
        u16 generation: 1;
        /* Should be zero. */
        u16 buffer_queue_id: 1;

        u16 header_len: 10;
        u16 rsc: 1;
        u16 split_header: 1;
        u16 reserved3: 4;

        u8 descriptor_done: 1;
        u8 end_of_packet: 1;
        u8 header_buffer_overflow: 1;
        u8 l3_l4_processed: 1;
        u8 csum_ip_err: 1;
        u8 csum_l4_err: 1;
        u8 csum_external_ip_err: 1;
        u8 csum_external_udp_err: 1;

        u8 status_error1;

        __le16 reserved5;
        __le16 buf_id; /* Buffer ID which was sent on the buffer queue. */

        union {
                /* Packet checksum. */
                __le16 raw_cs;
                /* Segment length for RSC packets. */
                __le16 rsc_seg_len;
        };
        __le32 hash;
        __le32 reserved6;
        __le64 reserved7;
} __packed;

static_assert(sizeof(struct gve_rx_compl_desc_dqo) == 32);

/* Ringing the doorbell too often can hurt performance.
 *
 * HW requires this value to be at least 8.
 */
#define GVE_RX_BUF_THRESH_DQO 32

#endif /* _GVE_DESC_DQO_H_ */