/*******************************************************************************
    Copyright (c) 2018 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 "nv-linux.h"
#include "nv-rsync.h"

nv_rsync_info_t g_rsync_info;

void nv_init_rsync_info(
    void
)
{
    g_rsync_info.relaxed_ordering_mode = NV_FALSE;
    g_rsync_info.usage_count = 0;
    g_rsync_info.data = NULL;
    NV_INIT_MUTEX(&g_rsync_info.lock);
}

void nv_destroy_rsync_info(
    void
)
{
    WARN_ON(g_rsync_info.data);
    WARN_ON(g_rsync_info.usage_count);
    WARN_ON(g_rsync_info.relaxed_ordering_mode);
}

int nv_get_rsync_info(
    void
)
{
    int mode;
    int rc = 0;

    down(&g_rsync_info.lock);

    if (g_rsync_info.usage_count == 0)
    {
        if (g_rsync_info.get_relaxed_ordering_mode)
        {
            rc = g_rsync_info.get_relaxed_ordering_mode(&mode,
                                                        g_rsync_info.data);
            if (rc != 0)
            {
                goto done;
            }

            g_rsync_info.relaxed_ordering_mode = !!mode;
        }
    }

    g_rsync_info.usage_count++;

done:
    up(&g_rsync_info.lock);

    return rc;
}

void nv_put_rsync_info(
    void
)
{
    int mode;

    down(&g_rsync_info.lock);

    g_rsync_info.usage_count--;

    if (g_rsync_info.usage_count == 0)
    {
        if (g_rsync_info.put_relaxed_ordering_mode)
        {
            mode = g_rsync_info.relaxed_ordering_mode;
            g_rsync_info.put_relaxed_ordering_mode(mode, g_rsync_info.data);
            g_rsync_info.relaxed_ordering_mode = NV_FALSE;
        }
    }

    up(&g_rsync_info.lock);
}

int nv_register_rsync_driver(
    int (*get_relaxed_ordering_mode)(int *mode, void *data),
    void (*put_relaxed_ordering_mode)(int mode, void *data),
    void (*wait_for_rsync)(struct pci_dev *gpu, void *data),
    void *data
)
{
    int rc = 0;

    down(&g_rsync_info.lock);

    if (g_rsync_info.get_relaxed_ordering_mode != NULL)
    {
        rc = -EBUSY;
        goto done;
    }

    if (g_rsync_info.usage_count != 0)
    {
        rc = -EBUSY;
        goto done;
    }

    g_rsync_info.get_relaxed_ordering_mode = get_relaxed_ordering_mode;
    g_rsync_info.put_relaxed_ordering_mode = put_relaxed_ordering_mode;
    g_rsync_info.wait_for_rsync = wait_for_rsync;
    g_rsync_info.data = data;

done:
    up(&g_rsync_info.lock);

    return rc;
}

void nv_unregister_rsync_driver(
    int (*get_relaxed_ordering_mode)(int *mode, void *data),
    void (*put_relaxed_ordering_mode)(int mode, void *data),
    void (*wait_for_rsync)(struct pci_dev *gpu, void *data),
    void *data
)
{
    down(&g_rsync_info.lock);

    WARN_ON(g_rsync_info.usage_count != 0);

    WARN_ON(g_rsync_info.get_relaxed_ordering_mode !=
            get_relaxed_ordering_mode);
    WARN_ON(g_rsync_info.put_relaxed_ordering_mode !=
            put_relaxed_ordering_mode);
    WARN_ON(g_rsync_info.wait_for_rsync != wait_for_rsync);
    WARN_ON(g_rsync_info.data != data);

    g_rsync_info.get_relaxed_ordering_mode = NULL;
    g_rsync_info.put_relaxed_ordering_mode = NULL;
    g_rsync_info.wait_for_rsync = NULL;
    g_rsync_info.data = NULL;

    up(&g_rsync_info.lock);
}

NvBool nv_get_rsync_relaxed_ordering_mode(
    nv_state_t *nv
)
{
    nv_linux_state_t *nvl = NV_GET_NVL_FROM_NV_STATE(nv);

    /* shouldn't be called without opening a device */
    WARN_ON(NV_ATOMIC_READ(nvl->usage_count) == 0);

    /*
     * g_rsync_info.relaxed_ordering_mode can be safely accessed outside of
     * g_rsync_info.lock once a device is opened. During nvidia_open(), we
     * lock the relaxed ordering state by ref-counting the rsync module
     * through get_relaxed_ordering_mode.
     */
    return g_rsync_info.relaxed_ordering_mode;
}

void nv_wait_for_rsync(
    nv_state_t *nv
)
{
    nv_linux_state_t *nvl = NV_GET_NVL_FROM_NV_STATE(nv);

    /* shouldn't be called without opening a device */
    WARN_ON(NV_ATOMIC_READ(nvl->usage_count) == 0);

    /*
     * g_rsync_info.relaxed_ordering_mode can be safely accessed outside of
     * g_rsync_info.lock once a device is opened. During nvidia_open(), we
     * block unregistration of the rsync driver by ref-counting the module
     * through get_relaxed_ordering_mode.
     */
    if (g_rsync_info.relaxed_ordering_mode)
    {
        WARN_ON(g_rsync_info.wait_for_rsync == NULL);
        g_rsync_info.wait_for_rsync(nvl->pci_dev, g_rsync_info.data);
    }
}
