/*******************************************************************************
    Copyright (c) 2020 NVidia Corporation
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to
    deal in the Software without restriction, including without limitation the
    rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
    sell copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
        The above copyright notice and this permission notice shall be
        included in all copies or substantial portions of the Software.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*******************************************************************************/

#include "nvlink.h"
#include "nvtypes.h"
#include "nvlink_export.h"
#include "nvlink_os.h"
#include "nvlink_ctx.h"
#include "nvlink_helper.h"
#include "nvlink_lock.h"

//
// Only enabling locking for testing purposes at the moment.
// Disabled at all other times.
//
#define LOCKING_DISABLED 1 

static void   _sort_links(nvlink_link **, NvU32, NvBool (*)(void *, void *));
static NvBool _compare(void *, void *);

/*
 * Allocate top level lock. Return NVL_SUCCESS if 
 * the lock was allocated else return NVL_ERR_GENERIC.
 */
NvlStatus
nvlink_lib_top_lock_alloc(void)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    void *top_lock = NULL;

    // Check if top level lock is already allocated
    if (nvlinkLibCtx.topLevelLock != NULL)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Top-level lock already allocated\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    top_lock = nvlink_allocLock();
    if (NULL == top_lock)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Failed to allocate top-level lock\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    nvlinkLibCtx.topLevelLock = top_lock; 

    // Top-level lock allocated

    return NVL_SUCCESS;
}

/*
 * Free top level lock. Return NVL_SUCCESS if 
 * the lock was freed else return NVL_ERR_GENERIC.
 */
NvlStatus
nvlink_lib_top_lock_free(void)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    // Check if already freed 
    if (NULL == nvlinkLibCtx.topLevelLock)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Top-level lock not allocated/already freed\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    nvlink_freeLock(nvlinkLibCtx.topLevelLock);
    nvlinkLibCtx.topLevelLock = NULL;

    // Top-level lock freed 
 
    return NVL_SUCCESS;
}

/*
 * Allocate per-link lock. Return NVL_SUCCESS if 
 * the lock was allocated else return NVL_ERR_GENERIC.
 */
NvlStatus
nvlink_lib_link_lock_alloc
(
    nvlink_link *link
)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    void *link_lock = NULL;

    // Check if already allocated
    if (link->linkLock != NULL)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Link lock already allocated on this link\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    link_lock = nvlink_allocLock();
    if (NULL == link_lock)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Failed to allocate link lock\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    // Link lock allocated
    link->linkLock = link_lock;

    return NVL_SUCCESS;
}

/*
 * Free per-link lock. Return NVL_SUCCESS if 
 * the lock was freed else return NVL_ERR_GENERIC.
 */
NvlStatus
nvlink_lib_link_lock_free
(
    nvlink_link *link
)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    // Check if already freed 
    if (NULL == link->linkLock)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Link lock not allocated/already freed\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    nvlink_freeLock(link->linkLock);
    link->linkLock = NULL;

    // Link lock freed

    return NVL_SUCCESS;
}

/*
 * Acquire top level lock. Return NVL_SUCCESS if 
 * the lock was acquired else return NVL_ERR_STATE_IN_USE.
 */
NvlStatus
nvlink_lib_top_lock_acquire(void)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    // Check if top-level lock is allocated before attempting to acquire
    if (NULL == nvlinkLibCtx.topLevelLock)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Top-level lock is not allocated\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    //
    // ToDo: Check if the lock was acquired succesfully
    // Currently the nvlink_acquireLock function doesn't report failures
    //
    nvlink_acquireLock(nvlinkLibCtx.topLevelLock);

    NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_INFO,
        "%s: Acquired top-level lock\n",
        __FUNCTION__));

    return NVL_SUCCESS;
}

/*
 * Release top level lock. Return NVL_SUCCESS if 
 * the lock was released else return NVL_ERR_GENERIC.
 */
NvlStatus
nvlink_lib_top_lock_release(void)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    // Check if top-level lock is allocated before attempting to release
    if (NULL == nvlinkLibCtx.topLevelLock)
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Top-level lock is not allocated\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    //
    // ToDo: Check if the lock was released succesfully
    // Currently the nvlink_releaseLock function doesn't report failures
    //
    nvlink_releaseLock(nvlinkLibCtx.topLevelLock);

    NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_INFO,
        "%s: Released top-level lock\n",
        __FUNCTION__));

    return NVL_SUCCESS;
}

/*
 * Sort the array of links in order of (DBDF, link#) - 
 * lowest to highest and acquire link locks.
 * Return NVL_SUCCESS if all the link locks were acquired.
 * Else if any link lock failed to be acquired, release 
 * all acquired link locks and return NVL_ERR_STATE_IN_USE.
 */
NvlStatus
nvlink_lib_link_locks_acquire
(
    nvlink_link **links,
    int           numLinks
)
{
    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    int i;

    nvlink_link *link_prev  = NULL;

    // Check if array of links is already empty before attempting to release. 
    if ((NULL == links) || (numLinks == 0))
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Could not release the link locks. Link array is empty !\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    // Sort the link array in increasing order of (DBDF, link#)
    _sort_links(links, numLinks, _compare);

    for (i = 0; i < numLinks; i++)
    {
        //
        // Don't acquire locks on loop back links twice since the current link is
        // the same as the previous one
        //
        if (links[i] != link_prev)
        {
            nvlink_acquireLock(links[i]->linkLock);

            NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_INFO,
                "%s: Acquire link lock for dom:%d bus:%d dev:%d fun:%d link:%d\n",
                __FUNCTION__,

			links[i]->dev->pciInfo.domain, links[i]->dev->pciInfo.bus,
			links[i]->dev->pciInfo.device, links[i]->dev->pciInfo.function,
			links[i]->linkNumber));
        }

        link_prev = links[i];
    }

    //
    // ToDo: Check if the lock was acquired succesfully
    // Currently the nvlink_acquireLock function doesn't report failures
    //
    return NVL_SUCCESS;
}

/*
 * Loop over all the links and call nvlink_releaseLock(links[i]->linkLock).
 * Return NVL_SUCCESS if all the link locks were released.
 * Else if any link lock failed to be released return NVL_ERR_GENERIC.
 */
NvlStatus
nvlink_lib_link_locks_release
(
    nvlink_link **links,
    int           numLinks
)
{
    int i;

    if (LOCKING_DISABLED)
    {
        return NVL_SUCCESS;
    }

    nvlink_link *link_prev  = NULL;

    // Check if array of links is already empty before attempting to release. 
    if ((NULL == links) || (numLinks == 0))
    {
        NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_ERRORS,
            "%s: Could not release the link locks. Link array is empty !\n",
            __FUNCTION__));

        return NVL_ERR_GENERIC; 
    }

    // Sort the link array in increasing order of (DBDF, link#)
    _sort_links(links, numLinks, _compare);

    for (i = 0; i < numLinks; i++)
    {
        //
        // Don't release locks on loop back links twice since the current link is
        // the same as the previous one
        //
        if (links[i] != link_prev)
        {
            nvlink_releaseLock(links[i]->linkLock);

            NVLINK_PRINT((DBG_MODULE_NVLINK_CORE, NVLINK_DBG_LEVEL_INFO,
                "%s: Release link lock for dom:%d bus:%d dev:%d fun:%d link:%d\n",
                __FUNCTION__,

			links[i]->dev->pciInfo.domain, links[i]->dev->pciInfo.bus,
			links[i]->dev->pciInfo.device, links[i]->dev->pciInfo.function,
			links[i]->linkNumber));
        }

        link_prev = links[i];
    }

    //
    // ToDo: Check if the lock was released succesfully
    // Currently the nvlink_releaseLock function doesn't report failures
    //
    return NVL_SUCCESS;
}

/*
 * Sorts the links in the increasing order of DBDF, link#
 */
static void
_sort_links
(
    nvlink_link **links,
    NvU32         numLinks,
    NvBool      (*compare)(void *, void *)
)
{
    nvlink_link *temp = NULL;
    NvU32        i, j;

    for (i = 0; i < numLinks; i++)
    {
        for (j = i + 1; j < numLinks; j++)
        {
            if (_compare(links[j], links[i]))
            {
                temp     = links[i];
                links[i] = links[j];
                links[j] = temp;
            }
        }
    }
}

/*
 * Compare function for _nvlink_sort - compares DBDF, link#
 */
static NvBool
_compare
(
    void *link1,
    void *link2
)
{
      nvlink_link *l1 = (nvlink_link *) link1;
      nvlink_link *l2 = (nvlink_link *) link2;
  
      // Compare link domains
      if (l1->dev->pciInfo.domain < l2->dev->pciInfo.domain)
      {
          return NV_TRUE;
      }
  
      if (l1->dev->pciInfo.domain > l2->dev->pciInfo.domain)
      {
          return NV_FALSE;
      }
  
      // Domain is same for devices of links. Compare bus next
  
      // Compare link buses 
      if (l1->dev->pciInfo.bus < l2->dev->pciInfo.bus)
      {
          return NV_TRUE;
      }
  
      if (l1->dev->pciInfo.bus > l2->dev->pciInfo.bus)
      {
          return NV_FALSE;
      }
  
      // Bus is same for devices of links. Compare device next
  
      // Compare link devices
      if (l1->dev->pciInfo.device < l2->dev->pciInfo.device)
      {
          return NV_TRUE;
      }
  
      if (l1->dev->pciInfo.device > l2->dev->pciInfo.device)
      {
          return NV_FALSE;
      }
  
      // Device is same for devices of links. Compare function next
  
      // Compare link functions
      if (l1->dev->pciInfo.function < l2->dev->pciInfo.function)
      {
          return NV_TRUE;
      }
  
      if (l1->dev->pciInfo.function > l2->dev->pciInfo.function)
      {
          return NV_FALSE;
      }
  
      // DBDF is same for both the links. Check the link#
  
      // Compare link numbers
      if (l1->linkNumber < l2->linkNumber)
      {
          return NV_TRUE;
      }
      else
      {
          return NV_FALSE;
      }
}
