/* $NetBSD: biosdisk_ll.c,v 1.31 2011/02/21 02:58:02 jakllsch Exp $ */

/* $NetBSD: biosdisk_ll.c,v 1.31 2011/02/21 02:58:02 jakllsch Exp $ */

/*-
* Copyright (c) 2005 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Bang Jun-Young.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/

/*
* Copyright (c) 1996
* Matthias Drochner. All rights reserved.
* Copyright (c) 1996
* Perry E. Metzger. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgements:
* This product includes software developed for the NetBSD Project
* by Matthias Drochner.
* This product includes software developed for the NetBSD Project
* by Perry E. Metzger.
* 4. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* 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.
*/

/*
* shared by bootsector startup (bootsectmain) and biosdisk.c
* needs lowlevel parts from bios_disk.S
*/

#include <lib/libkern/libkern.h>
#include <lib/libsa/stand.h>

#include "biosdisk_ll.h"
#include "diskbuf.h"
#include "libi386.h"

static int do_read(struct biosdisk_ll *, daddr_t, int, char *);

/*
* we get from get_diskinfo():
* %ah %ch %cl %dh (registers after int13/8), ie
* xxxxxxxx cccccccc CCssssss hhhhhhhh
*/
#define STATUS(di) ((di)>>24)
#define SPT(di) (((di)>>8)&0x3f)
#define HEADS(di) (((di)&0xff)+1)
#define CYL(di) (((((di)>>16)&0xff)|(((di)>>6)&0x300))+1)

#ifndef BIOSDISK_RETRIES
#define BIOSDISK_RETRIES 5
#endif

int
set_geometry(struct biosdisk_ll *d, struct biosdisk_extinfo *ed)
{
int diskinfo;

diskinfo = biosdisk_getinfo(d->dev);
d->sec = SPT(diskinfo);
d->head = HEADS(diskinfo);
d->cyl = CYL(diskinfo);
d->chs_sectors = d->sec * d->head * d->cyl;

if (d->dev >= 0x80 + get_harddrives()) {
d->secsize = 2048;
d->type = BIOSDISK_TYPE_CD;
} else {
d->secsize = 512;
if (d->dev & 0x80)
d->type = BIOSDISK_TYPE_HD;
else
d->type = BIOSDISK_TYPE_FD;
}

/*
* Some broken BIOSes such as one found on Soltek SL-75DRV2 report
* that they don't support int13 extension for CD-ROM drives while
* they actually do. As a workaround, if the boot device is a CD we
* assume that the extension is available. Note that only very old
* BIOSes don't support the extended mode, and they don't work with
* ATAPI CD-ROM drives, either. So there's no problem.
*/
d->flags = 0;
if (d->type == BIOSDISK_TYPE_CD ||
(d->type == BIOSDISK_TYPE_HD && biosdisk_int13ext(d->dev))) {
d->flags |= BIOSDISK_INT13EXT;
if (ed != NULL) {
ed->size = sizeof(*ed);
if (biosdisk_getextinfo(d->dev, ed) != 0)
return -1;
}
}

/*
* If the drive is 2.88MB floppy drive, check that we can actually
* read sector >= 18. If not, assume 1.44MB floppy disk.
*/
if (d->type == BIOSDISK_TYPE_FD && SPT(diskinfo) == 36) {
char buf[512];

if (biosdisk_read(d->dev, 0, 0, 18, 1, buf)) {
d->sec = 18;
d->chs_sectors /= 2;
}
}

return 0;
}

/*
* Global shared "diskbuf" is used as read ahead buffer. For reading from
* floppies, the bootstrap has to be loaded on a 64K boundary to ensure that
* this buffer doesn't cross a 64K DMA boundary.
*/
static int ra_dev;
static daddr_t ra_end;
static daddr_t ra_first;

/*
* Because some older BIOSes have bugs in their int13 extensions, we
* only try to use the extended read if the I/O request can't be addressed
* using CHS.
*
* Of course, some BIOSes have bugs in ths CHS read, such as failing to
* function properly if the MBR table has a different geometry than the
* BIOS would generate internally for the device in question, and so we
* provide a way to force the extended on hard disks via a compile-time
* option.
*/
#if defined(FORCE_INT13EXT)
#define NEED_INT13EXT(d, dblk, num) \
(((d)->dev & 0x80) != 0)
#else
#define NEED_INT13EXT(d, dblk, num) \
(((d)->type == BIOSDISK_TYPE_CD) || \
((d)->type == BIOSDISK_TYPE_HD && \
((dblk) + (num)) >= (d)->chs_sectors))
#endif

static int
do_read(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf)
{

if (NEED_INT13EXT(d, dblk, num)) {
struct {
int8_t size;
int8_t resvd;
int16_t cnt;
int16_t off;
int16_t seg;
int64_t sec;
} ext;

if (!(d->flags & BIOSDISK_INT13EXT))
return -1;
ext.size = sizeof(ext);
ext.resvd = 0;
ext.cnt = num;
/* seg:off of physical address */
ext.off = (int)buf & 0xf;
ext.seg = vtophys(buf) >> 4;
ext.sec = dblk;

if (biosdisk_extread(d->dev, &ext)) {
(void)biosdisk_reset(d->dev);
return -1;
}

return ext.cnt;
} else {
int cyl, head, sec, nsec, spc, dblk32;

dblk32 = (int)dblk;
spc = d->head * d->sec;
cyl = dblk32 / spc;
head = (dblk32 % spc) / d->sec;
sec = dblk32 % d->sec;
nsec = d->sec - sec;

if (nsec > num)
nsec = num;

if (biosdisk_read(d->dev, cyl, head, sec, nsec, buf)) {
(void)biosdisk_reset(d->dev);
return -1;
}

return nsec;
}
}

/*
* NB if 'cold' is set below not all of the program is loaded, so
* mustn't use data segment, bss, call library functions or do read-ahead.
*/
int
readsects(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf, int cold)
{
#ifdef BOOTXX
#define cold 1 /* collapse out references to diskbufp */
#endif
while (num) {
int nsec;

/* check for usable data in read-ahead buffer */
if (cold || diskbuf_user != &ra_dev || d->dev != ra_dev
|| dblk < ra_first || dblk >= ra_end) {

/* no, read from disk */
char *trbuf;
int maxsecs;
int retries = BIOSDISK_RETRIES;

if (cold) {
/* transfer directly to buffer */
trbuf = buf;
maxsecs = num;
} else {
/* fill read-ahead buffer */
trbuf = alloc_diskbuf(0); /* no data yet */
maxsecs = DISKBUFSIZE / d->secsize;
}

while ((nsec = do_read(d, dblk, maxsecs, trbuf)) < 0) {
#ifdef DISK_DEBUG
if (!cold)
printf("read error dblk %"PRId64"-%"PRId64"\n",
dblk, (dblk + maxsecs - 1));
#endif
if (--retries >= 0)
continue;
return -1; /* XXX cannot output here if
* (cold) */
}
if (!cold) {
ra_dev = d->dev;
ra_first = dblk;
ra_end = dblk + nsec;
diskbuf_user = &ra_dev;
}
} else /* can take blocks from end of read-ahead
* buffer */
nsec = ra_end - dblk;

if (!cold) {
/* copy data from read-ahead to user buffer */
if (nsec > num)
nsec = num;
memcpy(buf,
diskbufp + (dblk - ra_first) * d->secsize,
nsec * d->secsize);
}
buf += nsec * d->secsize;
num -= nsec;
dblk += nsec;
}

return 0;
}

/*
* Return the number of hard disk drives.
*/
int
get_harddrives(void)
{
/*
* Some BIOSes are buggy so that they return incorrect number
* of hard drives with int13/ah=8. We read a byte at 0040:0075
* instead, which is known to be always correct.
*/
int n = 0;

pvbcopy((void *)0x475, &n, 1);

return n;
}