/*-
 * Copyright (c) 2003 Alan L. Cox <alc@cs.rice.edu>
 * 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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 *
 * $FreeBSD: stable/10/sys/powerpc/include/sf_buf.h 255318 2013-09-06 17:44:13Z glebius $
 */

#ifndef _MACHINE_SF_BUF_H_
#define _MACHINE_SF_BUF_H_

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_page.h>
#include <machine/md_var.h>
#include <sys/queue.h>

struct vm_page;

struct sf_buf {
	LIST_ENTRY(sf_buf) list_entry;	/* list of buffers */
	TAILQ_ENTRY(sf_buf) free_entry;	/* list of buffers */
	struct		vm_page *m;	/* currently mapped page */
	vm_offset_t	kva;		/* va of mapping */
	int		ref_count;	/* usage of this mapping */
};

struct sf_buf * sf_buf_alloc(struct vm_page *m, int flags);
void sf_buf_free(struct sf_buf *sf);

/*
 * On 32-bit OEA, the only purpose for which sf_buf is used is to implement
 * an opaque pointer required by the machine-independent parts of the kernel.
 * That pointer references the vm_page that is "mapped" by the sf_buf.  The
 * actual mapping is provided by the direct virtual-to-physical mapping.  
 *
 * On OEA64 and Book-E, we need to do something a little more complicated. Use
 * the runtime-detected hw_direct_map to pick between the two cases. Our
 * friends in vm_machdep.c will do the same to ensure nothing gets confused.
 */

static __inline vm_offset_t
sf_buf_kva(struct sf_buf *sf)
{
	if (hw_direct_map)
		return (VM_PAGE_TO_PHYS((vm_page_t)sf));

	return (sf->kva);
}

static __inline struct vm_page *
sf_buf_page(struct sf_buf *sf)
{
	if (hw_direct_map)
		return ((vm_page_t)sf);

	return (sf->m);
}

#endif /* !_MACHINE_SF_BUF_H_ */
