virtqueue.h

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/*
 * Copyright (c) 2024 Antmicro <www.antmicro.com>
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 
#ifndef ZEPHYR_VIRTIO_VIRTQUEUE_H_
#define ZEPHYR_VIRTIO_VIRTQUEUE_H_
#include <stdint.h>
#include <stddef.h>
#include <zephyr/kernel.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
/*
 * Based on Virtual I/O Device (VIRTIO) Version 1.3 specification:
 * https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.pdf
 */


#define VIRTQ_DESC_F_NEXT 1
#define VIRTQ_DESC_F_WRITE 2

struct virtq_desc {
        uint64_t addr;
        uint32_t len;
        uint16_t flags;
        uint16_t next;
};

struct virtq_avail {
        uint16_t flags;
        uint16_t idx;
        uint16_t ring[];
};

struct virtq_used_elem {
        uint32_t id;
        uint32_t len;
};

struct virtq_used {
        uint16_t flags;
        uint16_t idx;
        struct virtq_used_elem ring[];
};

typedef void (*virtq_receive_callback)(void *opaque, uint32_t used_len);

struct virtq_receive_callback_entry {
        virtq_receive_callback cb;
        void *opaque;
};

struct virtq {
        struct k_spinlock lock;

        uint16_t num;
        struct virtq_desc *desc;
        struct virtq_avail *avail;
        struct virtq_used *used;

        uint16_t last_used_idx;
        struct k_stack free_desc_stack;

        uint16_t free_desc_n;

        struct virtq_receive_callback_entry *recv_cbs;
};
 

int virtq_create(struct virtq *v, size_t size);

void virtq_free(struct virtq *v);

struct virtq_buf {
        void *addr;
        uint32_t len;
};

int virtq_add_buffer_chain(
        struct virtq *v, struct virtq_buf *bufs, uint16_t bufs_size,
        uint16_t device_readable_count, virtq_receive_callback cb, void *cb_opaque,
        k_timeout_t timeout
);

void virtq_add_free_desc(struct virtq *v, uint16_t desc_idx);

int virtq_get_free_desc(struct virtq *v, uint16_t *desc_idx, k_timeout_t timeout);

 
#ifdef __cplusplus
}
#endif
 
#endif /* ZEPHYR_VIRTIO_VIRTQUEUE_H_ */