/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2022 Oxide Computer Company
 */

/*
 * VIRTIO 9P DRIVER
 */

#ifndef _VIO9P_IMPL_H
#define _VIO9P_IMPL_H

#include "virtio.h"
#include <sys/vio9p.h>

#ifdef __cplusplus
extern "C" {
#endif

/*
 * VIRTIO 9P CONFIGURATION REGISTERS
 *
 * These are offsets into the device-specific configuration space available
 * through the virtio_dev_*() family of functions.
 */
#define VIRTIO_9P_CONFIG_TAG_SZ                 0x00    /* 16 R   */
#define VIRTIO_9P_CONFIG_TAG                    0x02    /* SZ R   */

/*
 * VIRTIO 9P VIRTQUEUES
 *
 * Virtio 9P devices have just one queue which is used to make 9P requests.
 * Each submitted chain should include appropriately sized inbound and outbound
 * descriptors for the request and response messages.  The maximum size is
 * negotiated via the "msize" member of the 9P TVERSION request and RVERSION
 * response.  Some hypervisors may require the first 7 bytes (size, type, tag)
 * to be contiguous in the first descriptor.
 */
#define VIRTIO_9P_VIRTQ_REQUESTS        0

/*
 * VIRTIO 9P FEATURE BITS
 */
#define VIRTIO_9P_F_MOUNT_TAG           (1ULL << 0)

/*
 * These features are supported by the driver and we will request them from the
 * device.
 */
#define VIRTIO_9P_WANTED_FEATURES       (VIRTIO_9P_F_MOUNT_TAG)

/*
 * DRIVER PARAMETERS
 */

/*
 * A limit on the number of requests that can be allocated for a vio9p device.
 */
#define VIRTIO_9P_MAX_REQS              8

/*
 * This parameter defines an upper bound on 9P protocol message size (msize). 9P
 * servers may negotiate an msize up to this value. An attempt to transfer a
 * message larger than this will result in a EMSGISZE error.
 */
#define VIRTIO_9P_REQ_SIZE              65536

/*
 * It is not clear that there is a well-defined number of cookies for this
 * interface; QEMU may support as many as there are direct descriptors in the
 * ring, and bhyve may support something like 128.  We'll use a conservative
 * number that's large enough to ensure we'll be able to allocate without
 * requiring contiguous pages.
 */
#define VIRTIO_9P_MAX_SGL               64

/*
 * TYPE DEFINITIONS
 */

typedef enum vio9p_teardown_style {
        VIRTIO_9P_TEARDOWN_PRE_MUTEX,
        VIRTIO_9P_TEARDOWN_ATTACH,
        VIRTIO_9P_TEARDOWN_DETACH,
} vio9p_teardown_style_t;

typedef struct vio9p_req {
        virtio_dma_t                    *vnr_dma_in;
        virtio_dma_t                    *vnr_dma_out;
        virtio_chain_t                  *vnr_chain;
        list_node_t                     vnr_link;
        list_node_t                     vnr_link_complete;
        list_node_t                     vnr_link_free;
        uint64_t                        vnr_generation;
} vio9p_req_t;

typedef struct vio9p {
        dev_info_t                      *vin_dip;
        virtio_t                        *vin_virtio;
        virtio_queue_t                  *vin_vq;

        kmutex_t                        vin_mutex;
        kcondvar_t                      vin_cv;

        /*
         * When the device is opened, select a generation number.  This will be
         * used to discard completed responses that arrive after the device was
         * closed and reopened.
         */
        uint64_t                        vin_generation;
        bool                            vin_open;

        uint_t                          vin_nreqs;
        list_t                          vin_reqs;
        list_t                          vin_completes;

        list_t                          vin_req_freelist;

        char                            vin_tag[VIO9P_MOUNT_TAG_SIZE];
} vio9p_t;

#ifdef __cplusplus
}
#endif

#endif /* _VIO9P_IMPL_H */