/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011, Bryan Venteicher <bryanv@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _VIRTIO_VIRTQUEUE_H
#define _VIRTIO_VIRTQUEUE_H

struct virtqueue;
struct sglist;

/* Device callback for a virtqueue interrupt. */
typedef void virtqueue_intr_t(void *);

/*
 * Hint on how long the next interrupt should be postponed. This is
 * only used when the EVENT_IDX feature is negotiated.
 */
typedef enum {
        VQ_POSTPONE_SHORT,
        VQ_POSTPONE_LONG,
        VQ_POSTPONE_EMPTIED     /* Until all available desc are used. */
} vq_postpone_t;

#define VIRTQUEUE_MAX_NAME_SZ   32

/* One for each virtqueue the device wishes to allocate. */
struct vq_alloc_info {
        char               vqai_name[VIRTQUEUE_MAX_NAME_SZ];
        int                vqai_maxindirsz;
        virtqueue_intr_t  *vqai_intr;
        void              *vqai_intr_arg;
        struct virtqueue **vqai_vq;
};

#define VQ_ALLOC_INFO_INIT(_i,_nsegs,_intr,_arg,_vqp,_str,...) do {     \
        snprintf((_i)->vqai_name, VIRTQUEUE_MAX_NAME_SZ, _str,          \
            ##__VA_ARGS__);                                             \
        (_i)->vqai_maxindirsz = (_nsegs);                               \
        (_i)->vqai_intr = (_intr);                                      \
        (_i)->vqai_intr_arg = (_arg);                                   \
        (_i)->vqai_vq = (_vqp);                                         \
} while (0)

int      virtqueue_alloc(device_t dev, uint16_t queue, uint16_t size,
             bus_size_t notify_offset, int align, vm_paddr_t highaddr,
             struct vq_alloc_info *info, struct virtqueue **vqp);
void    *virtqueue_drain(struct virtqueue *vq, int *last);
void     virtqueue_free(struct virtqueue *vq);
int      virtqueue_reinit(struct virtqueue *vq, uint16_t size);

int      virtqueue_intr_filter(struct virtqueue *vq);
void     virtqueue_intr(struct virtqueue *vq);
int      virtqueue_enable_intr(struct virtqueue *vq);
int      virtqueue_postpone_intr(struct virtqueue *vq, vq_postpone_t hint);
void     virtqueue_disable_intr(struct virtqueue *vq);

/* Get physical address of the virtqueue ring. */
vm_paddr_t virtqueue_paddr(struct virtqueue *vq);
vm_paddr_t virtqueue_desc_paddr(struct virtqueue *vq);
vm_paddr_t virtqueue_avail_paddr(struct virtqueue *vq);
vm_paddr_t virtqueue_used_paddr(struct virtqueue *vq);

uint16_t virtqueue_index(struct virtqueue *vq);
bool     virtqueue_full(struct virtqueue *vq);
bool     virtqueue_empty(struct virtqueue *vq);
int      virtqueue_size(struct virtqueue *vq);
int      virtqueue_nfree(struct virtqueue *vq);
int      virtqueue_nused(struct virtqueue *vq);
void     virtqueue_notify(struct virtqueue *vq);
void     virtqueue_dump(struct virtqueue *vq);

int      virtqueue_enqueue(struct virtqueue *vq, void *cookie,
             struct sglist *sg, int readable, int writable);
void    *virtqueue_dequeue(struct virtqueue *vq, uint32_t *len);
void    *virtqueue_poll(struct virtqueue *vq, uint32_t *len);

#endif /* _VIRTIO_VIRTQUEUE_H */