/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012, 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_SCSIVAR_H
#define _VIRTIO_SCSIVAR_H

struct vtscsi_softc;
struct vtscsi_request;

typedef void vtscsi_request_cb_t(struct vtscsi_softc *,
    struct vtscsi_request *);

struct vtscsi_statistics {
        unsigned long           scsi_cmd_timeouts;
        unsigned long           dequeue_no_requests;
};

struct vtscsi_softc {
        device_t                 vtscsi_dev;
        struct mtx               vtscsi_mtx;
        uint64_t                 vtscsi_features;

        uint16_t                 vtscsi_flags;
#define VTSCSI_FLAG_INDIRECT            0x0001
#define VTSCSI_FLAG_BIDIRECTIONAL       0x0002
#define VTSCSI_FLAG_HOTPLUG             0x0004
#define VTSCSI_FLAG_RESET               0x0008
#define VTSCSI_FLAG_DETACH              0x0010

        uint16_t                 vtscsi_frozen;
#define VTSCSI_FROZEN_NO_REQUESTS       0x01
#define VTSCSI_FROZEN_REQUEST_VQ_FULL   0x02

        struct sglist           *vtscsi_sglist;

        struct virtqueue        *vtscsi_control_vq;
        struct virtqueue        *vtscsi_event_vq;
        struct virtqueue        *vtscsi_request_vq;

        struct cam_sim          *vtscsi_sim;
        struct cam_path         *vtscsi_path;

        int                      vtscsi_debug;
        int                      vtscsi_nrequests;
        int                      vtscsi_max_nsegs;
        int                      vtscsi_event_buf_size;

        TAILQ_HEAD(,vtscsi_request)
                                 vtscsi_req_free;

        uint16_t                 vtscsi_max_channel;
        uint16_t                 vtscsi_max_target;
        uint32_t                 vtscsi_max_lun;

#define VTSCSI_NUM_EVENT_BUFS   4
        struct virtio_scsi_event
                                 vtscsi_event_bufs[VTSCSI_NUM_EVENT_BUFS];

        struct vtscsi_statistics vtscsi_stats;
};

enum vtscsi_request_state {
        VTSCSI_REQ_STATE_FREE,
        VTSCSI_REQ_STATE_INUSE,
        VTSCSI_REQ_STATE_ABORTED,
        VTSCSI_REQ_STATE_TIMEDOUT
};

struct vtscsi_request {
        struct vtscsi_softc                     *vsr_softc;
        union ccb                               *vsr_ccb;
        vtscsi_request_cb_t                     *vsr_complete;

        void                                    *vsr_ptr0;
/* Request when aborting a timedout command. */
#define vsr_timedout_req        vsr_ptr0

        enum vtscsi_request_state                vsr_state;

        uint16_t                                 vsr_flags;
#define VTSCSI_REQ_FLAG_POLLED          0x01
#define VTSCSI_REQ_FLAG_COMPLETE        0x02
#define VTSCSI_REQ_FLAG_TIMEOUT_SET     0x04

        union {
                struct virtio_scsi_cmd_req       cmd;
                struct virtio_scsi_ctrl_tmf_req  tmf;
                struct virtio_scsi_ctrl_an_req   an;
        } vsr_ureq;
#define vsr_cmd_req     vsr_ureq.cmd
#define vsr_tmf_req     vsr_ureq.tmf
#define vsr_an_req      vsr_ureq.an

        /* Make request and response non-contiguous. */
        uint32_t                                 vsr_pad;

        union {
                struct virtio_scsi_cmd_resp      cmd;
                struct virtio_scsi_ctrl_tmf_resp tmf;
                struct virtio_scsi_ctrl_an_resp  an;
        } vsr_uresp;
#define vsr_cmd_resp    vsr_uresp.cmd
#define vsr_tmf_resp    vsr_uresp.tmf
#define vsr_an_resp     vsr_uresp.an

        struct callout                           vsr_callout;

        TAILQ_ENTRY(vtscsi_request)              vsr_link;
};

/* Private field in the CCB header that points to our request. */
#define ccbh_vtscsi_req spriv_ptr0

/* Features desired/implemented by this driver. */
#define VTSCSI_FEATURES \
    (VIRTIO_SCSI_F_HOTPLUG              | \
     VIRTIO_RING_F_INDIRECT_DESC)

#define VTSCSI_MTX(_sc)                 &(_sc)->vtscsi_mtx
#define VTSCSI_LOCK_INIT(_sc, _name)    mtx_init(VTSCSI_MTX(_sc), _name, \
                                            "VTSCSI Lock", MTX_DEF)
#define VTSCSI_LOCK(_sc)                mtx_lock(VTSCSI_MTX(_sc))
#define VTSCSI_UNLOCK(_sc)              mtx_unlock(VTSCSI_MTX(_sc))
#define VTSCSI_LOCK_OWNED(_sc)          mtx_assert(VTSCSI_MTX(_sc), MA_OWNED)
#define VTSCSI_LOCK_NOTOWNED(_sc)       mtx_assert(VTSCSI_MTX(_sc), MA_NOTOWNED)
#define VTSCSI_LOCK_DESTROY(_sc)        mtx_destroy(VTSCSI_MTX(_sc))

/*
 * Reasons for either freezing or thawing the SIMQ.
 *
 * VirtIO SCSI is a bit unique in the sense that SCSI and TMF
 * commands go over different queues. Both queues are fed by
 * the same SIMQ, but we only freeze the SIMQ when the request
 * (SCSI) virtqueue is full, not caring if the control (TMF)
 * virtqueue unlikely gets full. However, both queues share the
 * same pool of requests, so the completion of a TMF command
 * could cause the SIMQ to be unfrozen.
 */
#define VTSCSI_REQUEST          0x01
#define VTSCSI_REQUEST_VQ       0x02

/* Debug trace levels. */
#define VTSCSI_INFO     0x01
#define VTSCSI_ERROR    0x02
#define VTSCSI_TRACE    0x04

#define vtscsi_dprintf(_sc, _level, _msg, _args ...) do {               \
        if ((_sc)->vtscsi_debug & (_level))                             \
                device_printf((_sc)->vtscsi_dev, "%s: "_msg,            \
                    __FUNCTION__, ##_args);                             \
} while (0)

#define vtscsi_dprintf_req(_req, _level, _msg, _args ...) do {          \
        struct vtscsi_softc *__sc = (_req)->vsr_softc;                  \
        if ((__sc)->vtscsi_debug & (_level))                            \
                vtscsi_printf_req(_req, __FUNCTION__, _msg, ##_args);   \
} while (0)

/*
 * Set the status field in a CCB, optionally clearing non CCB_STATUS_* flags.
 */
#define vtscsi_set_ccb_status(_ccbh, _status, _mask) do {               \
        KASSERT(((_mask) & CAM_STATUS_MASK) == 0,                       \
            ("%s:%d bad mask: 0x%x", __FUNCTION__, __LINE__, (_mask))); \
        (_ccbh)->status &= ~(CAM_STATUS_MASK | (_mask));                \
        (_ccbh)->status |= (_status);                                   \
} while (0)

/*
 * One segment each for the request and the response.
 */
#define VTSCSI_MIN_SEGMENTS     2

/*
 * Allocate additional requests for internal use such
 * as TM commands (e.g. aborting timedout commands).
 */
#define VTSCSI_RESERVED_REQUESTS        10

/*
 * How to wait (or not) for request completion.
 */
#define VTSCSI_EXECUTE_ASYNC    0
#define VTSCSI_EXECUTE_POLL     1

#endif /* _VIRTIO_SCSIVAR_H */