/*
 * Copyright 2014 Red Hat Inc.
 *
 * 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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.
 *
 * Authors: Ben Skeggs <bskeggs@redhat.com>
 */

#include <nvif/client.h>
#include <nvif/driver.h>
#include <nvif/notify.h>
#include <nvif/object.h>
#include <nvif/ioctl.h>
#include <nvif/event.h>

static inline int
nvif_notify_put_(struct nvif_notify *notify)
{
        struct nvif_object *object = notify->object;
        struct {
                struct nvif_ioctl_v0 ioctl;
                struct nvif_ioctl_ntfy_put_v0 ntfy;
        } args = {
                .ioctl.type = NVIF_IOCTL_V0_NTFY_PUT,
                .ntfy.index = notify->index,
        };

        if (atomic_inc_return(&notify->putcnt) != 1)
                return 0;

        return nvif_object_ioctl(object, &args, sizeof(args), NULL);
}

int
nvif_notify_put(struct nvif_notify *notify)
{
        if (likely(notify->object) &&
            test_and_clear_bit(NVIF_NOTIFY_USER, &notify->flags)) {
                int ret = nvif_notify_put_(notify);
                if (test_bit(NVIF_NOTIFY_WORK, &notify->flags))
                        flush_work(&notify->work);
                return ret;
        }
        return 0;
}

static inline int
nvif_notify_get_(struct nvif_notify *notify)
{
        struct nvif_object *object = notify->object;
        struct {
                struct nvif_ioctl_v0 ioctl;
                struct nvif_ioctl_ntfy_get_v0 ntfy;
        } args = {
                .ioctl.type = NVIF_IOCTL_V0_NTFY_GET,
                .ntfy.index = notify->index,
        };

        if (atomic_dec_return(&notify->putcnt) != 0)
                return 0;

        return nvif_object_ioctl(object, &args, sizeof(args), NULL);
}

int
nvif_notify_get(struct nvif_notify *notify)
{
        if (likely(notify->object) &&
            !test_and_set_bit(NVIF_NOTIFY_USER, &notify->flags))
                return nvif_notify_get_(notify);
        return 0;
}

static inline int
nvif_notify_func(struct nvif_notify *notify, bool keep)
{
        int ret = notify->func(notify);
        if (ret == NVIF_NOTIFY_KEEP ||
            !test_and_clear_bit(NVIF_NOTIFY_USER, &notify->flags)) {
                if (!keep)
                        atomic_dec(&notify->putcnt);
                else
                        nvif_notify_get_(notify);
        }
        return ret;
}

static void
nvif_notify_work(struct work_struct *work)
{
        struct nvif_notify *notify = container_of(work, typeof(*notify), work);
        nvif_notify_func(notify, true);
}

int
nvif_notify(const void *header, u32 length, const void *data, u32 size)
{
        struct nvif_notify *notify = NULL;
        const union {
                struct nvif_notify_rep_v0 v0;
        } *args = header;
        int ret = NVIF_NOTIFY_DROP;

        if (length == sizeof(args->v0) && args->v0.version == 0) {
                if (WARN_ON(args->v0.route))
                        return NVIF_NOTIFY_DROP;
                notify = (void *)(unsigned long)args->v0.token;
        }

        if (!WARN_ON(notify == NULL)) {
                struct nvif_client *client = notify->object->client;
                if (!WARN_ON(notify->size != size)) {
                        atomic_inc(&notify->putcnt);
                        if (test_bit(NVIF_NOTIFY_WORK, &notify->flags)) {
                                memcpy((void *)notify->data, data, size);
                                schedule_work(&notify->work);
                                return NVIF_NOTIFY_DROP;
                        }
                        notify->data = data;
                        ret = nvif_notify_func(notify, client->driver->keep);
                        notify->data = NULL;
                }
        }

        return ret;
}

int
nvif_notify_fini(struct nvif_notify *notify)
{
        struct nvif_object *object = notify->object;
        struct {
                struct nvif_ioctl_v0 ioctl;
                struct nvif_ioctl_ntfy_del_v0 ntfy;
        } args = {
                .ioctl.type = NVIF_IOCTL_V0_NTFY_DEL,
                .ntfy.index = notify->index,
        };
        int ret = nvif_notify_put(notify);
        if (ret >= 0 && object) {
                ret = nvif_object_ioctl(object, &args, sizeof(args), NULL);
                notify->object = NULL;
                kfree((void *)notify->data);
        }
        return ret;
}

int
nvif_notify_init(struct nvif_object *object, int (*func)(struct nvif_notify *),
                 bool work, u8 event, void *data, u32 size, u32 reply,
                 struct nvif_notify *notify)
{
        struct {
                struct nvif_ioctl_v0 ioctl;
                struct nvif_ioctl_ntfy_new_v0 ntfy;
                struct nvif_notify_req_v0 req;
        } *args;
        int ret = -ENOMEM;

        notify->object = object;
        notify->flags = 0;
        atomic_set(&notify->putcnt, 1);
        notify->func = func;
        notify->data = NULL;
        notify->size = reply;
        if (work) {
                INIT_WORK(&notify->work, nvif_notify_work);
                set_bit(NVIF_NOTIFY_WORK, &notify->flags);
                notify->data = kmalloc(notify->size, GFP_KERNEL);
                if (!notify->data)
                        goto done;
        }

        if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
                goto done;
        args->ioctl.version = 0;
        args->ioctl.type = NVIF_IOCTL_V0_NTFY_NEW;
        args->ntfy.version = 0;
        args->ntfy.event = event;
        args->req.version = 0;
        args->req.reply = notify->size;
        args->req.route = 0;
        args->req.token = (unsigned long)(void *)notify;

        memcpy(args->req.data, data, size);
        ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
        notify->index = args->ntfy.index;
        kfree(args);
done:
        if (ret)
                nvif_notify_fini(notify);
        return ret;
}