/*
 * Copyright (c) 2019-2020 François Tigeot <ftigeot@wolfpond.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/dma-buf.h>
#include <linux/dma-fence.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/reservation.h>
#include <linux/mm.h>

struct fileops dmabuf_fileops;

static int
dmabuf_stat(struct file *fp, struct stat *sb, struct ucred *cred)
{
STUB();
	KASSERT(fp->f_type == DTYPE_DMABUF, ("fp is not DMABUF"));
	struct dma_buf *dmabuf = fp->private_data;

	memset(sb, 0, sizeof(*sb));
	sb->st_size = dmabuf->size;
	sb->st_mode = S_IFIFO;	/* XXX */

	return (0);
}

static int
dmabuf_close(struct file *fp)
{
	struct dma_buf *dmabuf;
	if (fp->f_ops != &dmabuf_fileops) {
		kprintf("dmabuf_close(): file->f_ops != &dmabuf_fileops\n");
		return EINVAL;
	}
	dmabuf = fp->private_data;
	dmabuf->ops->release(dmabuf);
	kfree(dmabuf);

	//kprintf("dmabuf_close(): success\n");
	return 0;
}

static int
dmabuf_ioctl(struct file *fp, u_long com, caddr_t data,
	    struct ucred *cred, struct sysmsg *msgv)
{
	kprintf("dmabuf_ioctl: com=%lu\n", com);
	return (EBADF);
}

static int
dmabuf_seek(struct file *fp, off_t offset, int whence, off_t *res)
{
	KASSERT(fp->f_type == DTYPE_DMABUF, ("fp is not DMABUF"));
	struct dma_buf *dmabuf = fp->private_data;
	off_t newoff;

	if (offset != 0) {
		return EINVAL;
	}

	switch (whence) {
	case SEEK_SET:
		newoff = 0;
		break;
	case SEEK_END:
		newoff = dmabuf->size;
		break;
	default:
		return EINVAL;
	}
	spin_lock(&fp->f_spin);
	fp->f_offset = newoff;
	spin_unlock(&fp->f_spin);
	*res = newoff;
	return 0;
	
}

struct fileops dmabuf_fileops = {
	.fo_read	= badfo_readwrite,
	.fo_write	= badfo_readwrite,
	.fo_ioctl	= dmabuf_ioctl,
	.fo_kqfilter	= badfo_kqfilter,
	.fo_stat	= dmabuf_stat,
	.fo_close	= dmabuf_close,
	.fo_seek	= dmabuf_seek,
};

struct dma_buf *
dma_buf_export(const struct dma_buf_export_info *exp_info)
{
	struct dma_buf *dmabuf;
	struct file *fp;

	falloc(curthread->td_lwp, &fp, NULL);
	if (fp == NULL)
		return ERR_PTR(-ENFILE);

	dmabuf = kmalloc(sizeof(struct dma_buf), M_DRM, M_WAITOK);
	fp->f_type = DTYPE_DMABUF;
	fp->f_ops = &dmabuf_fileops;
	fp->private_data = dmabuf;
	dmabuf->priv = exp_info->priv;
	dmabuf->ops = exp_info->ops;
	dmabuf->size = exp_info->size;
	dmabuf->file = fp;

	return dmabuf;
}

int
dma_buf_fd(struct dma_buf *dmabuf, int flags)
{
	int fd, error;

	if (dmabuf == NULL)
		return -EINVAL;

	if (dmabuf->file == NULL)
		return -EINVAL;

	if (flags & O_CLOEXEC) {
	/* XXX: CLOEXEC not handled yet */
#if 0
		__set_close_on_exec(fd, fdt);
	else
		__clear_close_on_exec(fd, fdt);
#endif
	}

	error = fdalloc(curproc, 0, &fd);
	if (error != 0)
		return -error;

	fsetfd(curproc->p_fd, dmabuf->file, fd);

	return fd;
}

struct dma_buf *
dma_buf_get(int fd)
{
	struct file *fp;
	struct dma_buf *dmabuf;

	if ((fp = holdfp(curthread, fd, -1)) == NULL)
		return ERR_PTR(-EBADF);

	if (fp->f_ops != &dmabuf_fileops) {
		kprintf("dma_buf_get(): file->f_ops != &dmabuf_fileops\n");
		dropfp(curthread, fd, fp);
		return ERR_PTR(-EBADF);
	}

	dmabuf = fp->private_data;
	dropfp(curthread, fd, fp);

	return dmabuf;
}

struct sg_table *
dma_buf_map_attachment(struct dma_buf_attachment *attach,
				enum dma_data_direction direction)
{
STUB();
	struct sg_table *sg_table;

	if (attach == NULL)
		return ERR_PTR(-EINVAL);

	if (attach->dmabuf == NULL)
		return ERR_PTR(-EINVAL);

	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
	if (sg_table == NULL)
		return ERR_PTR(-ENOMEM);

	return sg_table;
}

void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
				struct sg_table *sg_table,
				enum dma_data_direction direction)
{
STUB();
}