/*
 * Copyright (C) 2013 Red Hat
 *
 * 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 (including the next
 * paragraph) 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 <linux/export.h>
#include <linux/slab.h>

#include <drm/drm_flip_work.h>
#include <drm/drm_print.h>
#include <drm/drm_util.h>

struct drm_flip_task {
        struct list_head node;
        void *data;
};

static struct drm_flip_task *drm_flip_work_allocate_task(void *data, gfp_t flags)
{
        struct drm_flip_task *task;

        task = kzalloc_obj(*task, flags);
        if (task)
                task->data = data;

        return task;
}

static void drm_flip_work_queue_task(struct drm_flip_work *work, struct drm_flip_task *task)
{
        unsigned long flags;

        spin_lock_irqsave(&work->lock, flags);
        list_add_tail(&task->node, &work->queued);
        spin_unlock_irqrestore(&work->lock, flags);
}

/**
 * drm_flip_work_queue - queue work
 * @work: the flip-work
 * @val: the value to queue
 *
 * Queues work, that will later be run (passed back to drm_flip_func_t
 * func) on a work queue after drm_flip_work_commit() is called.
 */
void drm_flip_work_queue(struct drm_flip_work *work, void *val)
{
        struct drm_flip_task *task;

        task = drm_flip_work_allocate_task(val,
                                drm_can_sleep() ? GFP_KERNEL : GFP_ATOMIC);
        if (task) {
                drm_flip_work_queue_task(work, task);
        } else {
                DRM_ERROR("%s could not allocate task!\n", work->name);
                work->func(work, val);
        }
}
EXPORT_SYMBOL(drm_flip_work_queue);

/**
 * drm_flip_work_commit - commit queued work
 * @work: the flip-work
 * @wq: the work-queue to run the queued work on
 *
 * Trigger work previously queued by drm_flip_work_queue() to run
 * on a workqueue.  The typical usage would be to queue work (via
 * drm_flip_work_queue()) at any point (from vblank irq and/or
 * prior), and then from vblank irq commit the queued work.
 */
void drm_flip_work_commit(struct drm_flip_work *work,
                struct workqueue_struct *wq)
{
        unsigned long flags;

        spin_lock_irqsave(&work->lock, flags);
        list_splice_tail(&work->queued, &work->commited);
        INIT_LIST_HEAD(&work->queued);
        spin_unlock_irqrestore(&work->lock, flags);
        queue_work(wq, &work->worker);
}
EXPORT_SYMBOL(drm_flip_work_commit);

static void flip_worker(struct work_struct *w)
{
        struct drm_flip_work *work = container_of(w, struct drm_flip_work, worker);
        struct list_head tasks;
        unsigned long flags;

        while (1) {
                struct drm_flip_task *task, *tmp;

                INIT_LIST_HEAD(&tasks);
                spin_lock_irqsave(&work->lock, flags);
                list_splice_tail(&work->commited, &tasks);
                INIT_LIST_HEAD(&work->commited);
                spin_unlock_irqrestore(&work->lock, flags);

                if (list_empty(&tasks))
                        break;

                list_for_each_entry_safe(task, tmp, &tasks, node) {
                        work->func(work, task->data);
                        kfree(task);
                }
        }
}

/**
 * drm_flip_work_init - initialize flip-work
 * @work: the flip-work to initialize
 * @name: debug name
 * @func: the callback work function
 *
 * Initializes/allocates resources for the flip-work
 */
void drm_flip_work_init(struct drm_flip_work *work,
                const char *name, drm_flip_func_t func)
{
        work->name = name;
        INIT_LIST_HEAD(&work->queued);
        INIT_LIST_HEAD(&work->commited);
        spin_lock_init(&work->lock);
        work->func = func;

        INIT_WORK(&work->worker, flip_worker);
}
EXPORT_SYMBOL(drm_flip_work_init);

/**
 * drm_flip_work_cleanup - cleans up flip-work
 * @work: the flip-work to cleanup
 *
 * Destroy resources allocated for the flip-work
 */
void drm_flip_work_cleanup(struct drm_flip_work *work)
{
        WARN_ON(!list_empty(&work->queued) || !list_empty(&work->commited));
}
EXPORT_SYMBOL(drm_flip_work_cleanup);