boot/common/md.c

	md.c revision 199767f8919635c4928607450d9e0abb932109ce
/*-
 * Copyright (c) 2009 Marcel Moolenaar
 * 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <stand.h>
#include <sys/param.h>
#include <sys/endian.h>
#include <sys/queue.h>
#include <machine/stdarg.h>

#include "bootstrap.h"

#define MD_BLOCK_SIZE   512

#ifndef MD_IMAGE_SIZE
#error Must be compiled with MD_IMAGE_SIZE defined
#endif
#if (MD_IMAGE_SIZE == 0 || MD_IMAGE_SIZE % MD_BLOCK_SIZE)
#error Image size must be a multiple of 512.
#endif

/*
 * Preloaded image gets put here.
 * Applications that patch the object with the image can determine
 * the size looking at the start and end markers (strings),
 * so we want them contiguous.
 */
static struct {
    u_char start[MD_IMAGE_SIZE];
    u_char end[128];
} md_image = {
    .start = "MFS Filesystem goes here",
    .end = "MFS Filesystem had better STOP here",
};

/* devsw I/F */
static int md_init(void);
static int md_strategy(void *, int, daddr_t, size_t, char *, size_t *);
static int md_open(struct open_file *, ...);
static int md_close(struct open_file *);
static void md_print(int);

struct devsw md_dev = {
    "md",
    DEVT_DISK,
    md_init,
    md_strategy,
    md_open,
    md_close,
    noioctl,
    md_print
};

static int
md_init(void)
{

    return (0);
}

static int
md_strategy(void *devdata, int rw, daddr_t blk, size_t size, char *buf,
    size_t *rsize)
{
    struct devdesc *dev = (struct devdesc *)devdata;
    size_t ofs;

    if (dev->d_unit != 0)
        return (ENXIO);

    if (blk < 0 || blk >= (MD_IMAGE_SIZE / MD_BLOCK_SIZE))
        return (EIO);

    if (size % MD_BLOCK_SIZE)
        return (EIO);

    ofs = blk * MD_BLOCK_SIZE;
    if ((ofs + size) > MD_IMAGE_SIZE)
        size = MD_IMAGE_SIZE - ofs;

    if (rsize != 0)
        *rsize = size;

    switch (rw) {
    case F_READ:
        bcopy(md_image.start + ofs, buf, size);
        return (0);
    case F_WRITE:
        bcopy(buf, md_image.start + ofs, size);
        return (0);
    }

    return (ENODEV);
}

static int
md_open(struct open_file *f, ...)
{
    va_list ap;
    struct devdesc *dev;

    va_start(ap, f);
    dev = va_arg(ap, struct devdesc *);
    va_end(ap);

    if (dev->d_unit != 0)
        return (ENXIO);

    return (0);
}

static int
md_close(struct open_file *f)
{
    struct devdesc *dev;

    dev = (struct devdesc *)(f->f_devdata);
    return ((dev->d_unit != 0) ? ENXIO : 0);
}

static void
md_print(int verbose)
{

    printf("MD (%u bytes)\n", MD_IMAGE_SIZE);
}