/* $NetBSD: dkwedge_tos.c,v 1.2 2024/04/06 09:51:34 hannken Exp $ */

/* $NetBSD: dkwedge_tos.c,v 1.2 2024/04/06 09:51:34 hannken Exp $ */

/*
* Copyright (c) 2024 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Charlotte Koch.
*
* 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.
*/

/*
* dk(4) support for Atari "TOS" partition schemes.
*
* Technical details taken from:
*
* - "Atari Hard Disk File Systems Reference Guide" v1.2b by Jean
* Louis-Guerin (DrCoolZic) (September 2014)
*
* https://info-coach.fr/atari/documents/_mydoc/Atari_HD_File_Sytem_Reference_Guide.pdf
*/

#include <sys/buf.h>
#include <sys/disk.h>
#include <sys/endian.h>
#include <sys/vnode.h>

#define TOS_PART_TYPE_LEN 3
#define TOS_GEM_PARTITION "GEM"
#define TOS_BGM_PARTITION "BGM"
#define TOS_XGM_PARTITION "XGM"

#define TOS_CXNMETHOD_SASI 0x00
#define TOS_CXNMETHOD_SCSI 0xFF

#define TOS_MAX_PART_COUNT 4
#define TOS_SECTOR_SIZE 512

struct tos_partition {
uint8_t status;
char type[TOS_PART_TYPE_LEN];
uint32_t offset;
uint32_t size;
} __packed;
__CTASSERT(sizeof(struct tos_partition) == 12);

struct tos_root_sector {
uint8_t unused1[441];
uint8_t connection_method;
uint8_t unused2[8];
uint32_t size;
struct tos_partition parts[TOS_MAX_PART_COUNT];
uint8_t unused3[10];
} __packed;
__CTASSERT(sizeof(struct tos_root_sector) == TOS_SECTOR_SIZE);

static int dkwedge_discover_tos(struct disk *pdk, struct vnode *vp);

static int
dkwedge_discover_tos(struct disk *pdk, struct vnode *vp)
{
struct dkwedge_info dkw;
int error = 0;
size_t i;
char safe_type[4];

/* Get ourselves a fistful of memory. */
buf_t *bp = geteblk(TOS_SECTOR_SIZE);

error = dkwedge_read(pdk, vp, 0L, bp->b_data, TOS_SECTOR_SIZE);
if (error) {
aprint_error("unable to read TOS Root Sector: error = %d",
error);
goto out;
}

struct tos_root_sector *trs = bp->b_data;

/*
* If the "connection method" isn't recognized, then this is
* probably NOT an Atari-style partition, so get outta here. Note
* that there really isn't a magic number we can rely on; this check
* is somewhat made up. But at least it's better than nothing.
*/
switch (trs->connection_method) {
case TOS_CXNMETHOD_SASI: /* FALLTHROUGH */
case TOS_CXNMETHOD_SCSI:
; /* OK */
break;
default:
error = ESRCH;
goto out;
}

/*
* Make a wedge for each partition that exists (i.e., has the "exist"
* bit set).
*/
for (i = 0; i < TOS_MAX_PART_COUNT; i++) {
struct tos_partition part = trs->parts[i];

if (!(part.status & 0x01))
continue;

/* Ignore if we see it's an extended "XGM" partition. */
if (!strncmp(part.type, TOS_XGM_PARTITION, TOS_PART_TYPE_LEN)) {
aprint_normal(
"WARNING: XGM partitions are not yet supported\n");
continue;
}

/*
* Otherwise, get outta here if it's not the partition-types
* we *do* support.
*/
if (strncmp(part.type, TOS_GEM_PARTITION, TOS_PART_TYPE_LEN) &&
strncmp(part.type, TOS_BGM_PARTITION, TOS_PART_TYPE_LEN)) {
error = ESRCH;
goto out;
}

memset(&dkw, 0, sizeof(dkw));
memset(safe_type, 0, sizeof(safe_type));

/*
* The partition type string is NOT NUL-terminated, so let's
* play it safe.
*/
memcpy(safe_type, part.type, TOS_PART_TYPE_LEN);
safe_type[TOS_PART_TYPE_LEN] = '\0';

/* Finally, make the wedge. */
snprintf(dkw.dkw_wname, sizeof(dkw.dkw_wname), "ATARI_%s_%02zu",
safe_type, i);
dkw.dkw_offset = be32toh(trs->parts[i].offset);
dkw.dkw_size = be32toh(trs->parts[i].size);
strlcpy(dkw.dkw_ptype, DKW_PTYPE_FAT, sizeof(dkw.dkw_ptype));
strlcpy(dkw.dkw_parent, pdk->dk_name, sizeof(dkw.dkw_parent));
error = dkwedge_add(&dkw);

if (error == EEXIST) {
aprint_error("partition named \"%s\" already exists",
dkw.dkw_wname);
goto out;
}
}

error = 0;

out:
brelse(bp, 0);
return error;
}

DKWEDGE_DISCOVERY_METHOD_DECL(TOS, 10, dkwedge_discover_tos);