/* $Id: VirtioRing-solaris.c 38736 2011-09-13 13:58:47Z vboxsync $ */
/** @file
 * VirtualBox Guest Additions: Virtio Driver for Solaris, Ring implementation.
 */

/*
 * Copyright (C) 2010 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */

/*******************************************************************************
*   Header Files                                                               *
*******************************************************************************/
#ifdef DEBUG_ramshankar
# define LOG_INSTANCE       RTLogRelDefaultInstance()
#endif
#include "Virtio-solaris.h"

#include <iprt/asm.h>
#include <iprt/cdefs.h>
#include <iprt/assert.h>
#include <iprt/err.h>
#include <iprt/log.h>

#include <sys/cmn_err.h>

/**
 * Returns the size of the ring in bytes given the number of elements and
 * alignment requirements.
 *
 * @param cElements         Number of elements.
 * @param Align             Alignment (must be a power of two).
 *
 * @return Size of the Virtio ring.
 */
size_t VirtioRingSize(uint64_t cElements, ulong_t Align)
{
    size_t cb = 0;
    cb  = cElements * sizeof(VIRTIORINGDESC);   /* Ring descriptors. */
    cb += 2 * sizeof(uint16_t);                 /* Available flags and index. */
    cb += cElements * sizeof(uint16_t);         /* Available descriptors. */

    size_t cbAlign = RT_ALIGN_Z(cb, Align);
    cbAlign += 2 * sizeof(uint16_t);                    /* Used flags and index. */
    cbAlign += cElements * sizeof(VIRTIORINGUSEDELEM);  /* Used descriptors. */

    return cbAlign;
}


/**
 * Initializes a ring of a queue. This associates the DMA virtual address
 * with the Ring structure's "pRingDesc".
 *
 * @param pQueue            Pointer to the Virtio Queue.
 * @param cDescs            Number of descriptors.
 * @param virtBuf           Buffer associated with the ring.
 * @param Align             Alignment (must be power of two).
 */
void VirtioRingInit(PVIRTIOQUEUE pQueue, uint_t cDescs, caddr_t virtBuf, ulong_t Align)
{
    PVIRTIORING pRing = &pQueue->Ring;
    pRing->cDesc          = cDescs;
    pRing->pRingDesc      = (void *)virtBuf;
    pRing->pRingAvail     = (PVIRTIORINGAVAIL)(virtBuf + (cDescs * sizeof(pRing->pRingDesc[0])));
    pRing->pRingUsedElem  = RT_ALIGN_PT(pRing->pRingAvail + RT_OFFSETOF(VIRTIORINGAVAIL, aRings[pQueue->Ring.cDesc]), Align,
                                        PVIRTIORINGUSEDELEM);

    for (uint_t i = 0; i < pRing->cDesc - 1; i++)
        pRing->pRingDesc[i].Next = i + 1;

    pQueue->FreeHeadIndex = 0;

    cmn_err(CE_NOTE, "cDesc=%u pRingDesc=%p pRingAvail=%p\n", pRing->cDesc, pRing->pRingDesc, pRing->pRingAvail);
}


/**
 * Push a buffer into the ring.
 *
 * @param pQueue            Pointer to the Virtio queue.
 * @param physBuf           Physical address of the buffer.
 * @param cbBuf             Size of the buffer in bytes.
 * @param fFlags            Buffer flags, see VIRTIO_FLAGS_RING_DESC_*.
 *
 * @return IPRT error code.
 */
int VirtioRingPush(PVIRTIOQUEUE pQueue, paddr_t physBuf, uint32_t cbBuf, uint16_t fFlags)
{
    /*
     * Claim a slot, fill the buffer and move head pointer.
     */
    uint_t FreeIndex          = pQueue->FreeHeadIndex;
    PVIRTIORING pRing         = &pQueue->Ring;

    if (FreeIndex >= pRing->cDesc - 1)
    {
        LogRel((VIRTIOLOGNAME ":VirtioRingPush: failed. No free descriptors. cDesc=%u\n", pRing->cDesc));
        return VERR_BUFFER_OVERFLOW;
    }

    PVIRTIORINGDESC pRingDesc = &pRing->pRingDesc[FreeIndex];

    AssertCompile(sizeof(physBuf) == sizeof(pRingDesc->AddrBuf));

    pQueue->cBufs++;
    uint_t AvailIndex = (pRing->pRingAvail->Index + pQueue->cBufs) % pQueue->Ring.cDesc;
    pRing->pRingAvail->aRings[AvailIndex - 1] = FreeIndex;

    pRingDesc->AddrBuf = physBuf;
    pRingDesc->cbBuf   = cbBuf;
    pRingDesc->fFlags  = fFlags;

    pQueue->FreeHeadIndex = pRingDesc->Next;

    ASMCompilerBarrier();

    cmn_err(CE_NOTE, "VirtioRingPush: cbBuf=%u FreeIndex=%u AvailIndex=%u cDesc=%u Queue->cBufs=%u\n",
            cbBuf, FreeIndex, AvailIndex, pQueue->Ring.cDesc,
            pQueue->cBufs);

    return VINF_SUCCESS;
}