/* SPDX-License-Identifier: MIT */
/* Copyright (C) 2006-2017 Oracle Corporation */

#ifndef __HGSMI_DEFS_H__
#define __HGSMI_DEFS_H__

/* Buffer sequence type mask. */
#define HGSMI_BUFFER_HEADER_F_SEQ_MASK     0x03
/* Single buffer, not a part of a sequence. */
#define HGSMI_BUFFER_HEADER_F_SEQ_SINGLE   0x00
/* The first buffer in a sequence. */
#define HGSMI_BUFFER_HEADER_F_SEQ_START    0x01
/* A middle buffer in a sequence. */
#define HGSMI_BUFFER_HEADER_F_SEQ_CONTINUE 0x02
/* The last buffer in a sequence. */
#define HGSMI_BUFFER_HEADER_F_SEQ_END      0x03

/* 16 bytes buffer header. */
struct hgsmi_buffer_header {
        u32 data_size;          /* Size of data that follows the header. */
        u8 flags;               /* HGSMI_BUFFER_HEADER_F_* */
        u8 channel;             /* The channel the data must be routed to. */
        u16 channel_info;       /* Opaque to the HGSMI, used by the channel. */

        union {
                /* Opaque placeholder to make the union 8 bytes. */
                u8 header_data[8];

                /* HGSMI_BUFFER_HEADER_F_SEQ_SINGLE */
                struct {
                        u32 reserved1;  /* A reserved field, initialize to 0. */
                        u32 reserved2;  /* A reserved field, initialize to 0. */
                } buffer;

                /* HGSMI_BUFFER_HEADER_F_SEQ_START */
                struct {
                        /* Must be the same for all buffers in the sequence. */
                        u32 sequence_number;
                        /* The total size of the sequence. */
                        u32 sequence_size;
                } sequence_start;

                /*
                 * HGSMI_BUFFER_HEADER_F_SEQ_CONTINUE and
                 * HGSMI_BUFFER_HEADER_F_SEQ_END
                 */
                struct {
                        /* Must be the same for all buffers in the sequence. */
                        u32 sequence_number;
                        /* Data offset in the entire sequence. */
                        u32 sequence_offset;
                } sequence_continue;
        } u;
} __packed;

/* 8 bytes buffer tail. */
struct hgsmi_buffer_tail {
        /* Reserved, must be initialized to 0. */
        u32 reserved;
        /*
         * One-at-a-Time Hash: https://www.burtleburtle.net/bob/hash/doobs.html
         * Over the header, offset and for first 4 bytes of the tail.
         */
        u32 checksum;
} __packed;

/*
 * The size of the array of channels. Array indexes are u8.
 * Note: the value must not be changed.
 */
#define HGSMI_NUMBER_OF_CHANNELS 0x100

#endif