acorn.c

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/*
 *  linux/fs/partitions/acorn.c
 *
 *  Copyright (c) 1996-2000 Russell King.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Scan ADFS partitions on hard disk drives.  Unfortunately, there
 *  isn't a standard for partitioning drives on Acorn machines, so
 *  every single manufacturer of SCSI and IDE cards created their own
 *  method.
 */
#include <linux/buffer_head.h>
#include <linux/adfs_fs.h>

#include "check.h"
#include "acorn.h"

/*
 * Partition types. (Oh for reusability)
 */
#define PARTITION_RISCIX_MFM    1
#define PARTITION_RISCIX_SCSI   2
#define PARTITION_LINUX     9

#if defined(CONFIG_ACORN_PARTITION_CUMANA) || \
    defined(CONFIG_ACORN_PARTITION_ADFS)
static struct adfs_discrecord *
adfs_partition(struct parsed_partitions *state, char *name, char *data,
           unsigned long first_sector, int slot)
{
    struct adfs_discrecord *dr;
    unsigned int nr_sects;

    if (adfs_checkbblk(data))
        return NULL;

    dr = (struct adfs_discrecord *)(data + 0x1c0);

    if (dr->disc_size == 0 && dr->disc_size_high == 0)
        return NULL;

    nr_sects = (le32_to_cpu(dr->disc_size_high) << 23) |
           (le32_to_cpu(dr->disc_size) >> 9);

    if (name) {
        strlcat(state->pp_buf, " [", PAGE_SIZE);
        strlcat(state->pp_buf, name, PAGE_SIZE);
        strlcat(state->pp_buf, "]", PAGE_SIZE);
    }
    put_partition(state, slot, first_sector, nr_sects);
    return dr;
}
#endif

#ifdef CONFIG_ACORN_PARTITION_RISCIX

struct riscix_part {
    __le32  start;
    __le32  length;
    __le32  one;
    char    name[16];
};

struct riscix_record {
    __le32  magic;
#define RISCIX_MAGIC    cpu_to_le32(0x4a657320)
    __le32  date;
    struct riscix_part part[8];
};

#if defined(CONFIG_ACORN_PARTITION_CUMANA) || \
    defined(CONFIG_ACORN_PARTITION_ADFS)
static int riscix_partition(struct parsed_partitions *state,
                unsigned long first_sect, int slot,
                unsigned long nr_sects)
{
    Sector sect;
    struct riscix_record *rr;
    
    rr = read_part_sector(state, first_sect, &sect);
    if (!rr)
        return -1;

    strlcat(state->pp_buf, " [RISCiX]", PAGE_SIZE);


    if (rr->magic == RISCIX_MAGIC) {
        unsigned long size = nr_sects > 2 ? 2 : nr_sects;
        int part;

        strlcat(state->pp_buf, " <", PAGE_SIZE);

        put_partition(state, slot++, first_sect, size);
        for (part = 0; part < 8; part++) {
            if (rr->part[part].one &&
                memcmp(rr->part[part].name, "All\0", 4)) {
                put_partition(state, slot++,
                    le32_to_cpu(rr->part[part].start),
                    le32_to_cpu(rr->part[part].length));
                strlcat(state->pp_buf, "(", PAGE_SIZE);
                strlcat(state->pp_buf, rr->part[part].name, PAGE_SIZE);
                strlcat(state->pp_buf, ")", PAGE_SIZE);
            }
        }

        strlcat(state->pp_buf, " >\n", PAGE_SIZE);
    } else {
        put_partition(state, slot++, first_sect, nr_sects);
    }

    put_dev_sector(sect);
    return slot;
}
#endif
#endif

#define LINUX_NATIVE_MAGIC 0xdeafa1de
#define LINUX_SWAP_MAGIC   0xdeafab1e

struct linux_part {
    __le32 magic;
    __le32 start_sect;
    __le32 nr_sects;
};

#if defined(CONFIG_ACORN_PARTITION_CUMANA) || \
    defined(CONFIG_ACORN_PARTITION_ADFS)
static int linux_partition(struct parsed_partitions *state,
               unsigned long first_sect, int slot,
               unsigned long nr_sects)
{
    Sector sect;
    struct linux_part *linuxp;
    unsigned long size = nr_sects > 2 ? 2 : nr_sects;

    strlcat(state->pp_buf, " [Linux]", PAGE_SIZE);

    put_partition(state, slot++, first_sect, size);

    linuxp = read_part_sector(state, first_sect, &sect);
    if (!linuxp)
        return -1;

    strlcat(state->pp_buf, " <", PAGE_SIZE);
    while (linuxp->magic == cpu_to_le32(LINUX_NATIVE_MAGIC) ||
           linuxp->magic == cpu_to_le32(LINUX_SWAP_MAGIC)) {
        if (slot == state->limit)
            break;
        put_partition(state, slot++, first_sect +
                 le32_to_cpu(linuxp->start_sect),
                 le32_to_cpu(linuxp->nr_sects));
        linuxp ++;
    }
    strlcat(state->pp_buf, " >", PAGE_SIZE);

    put_dev_sector(sect);
    return slot;
}
#endif

#ifdef CONFIG_ACORN_PARTITION_CUMANA
int adfspart_check_CUMANA(struct parsed_partitions *state)
{
    unsigned long first_sector = 0;
    unsigned int start_blk = 0;
    Sector sect;
    unsigned char *data;
    char *name = "CUMANA/ADFS";
    int first = 1;
    int slot = 1;

    /*
     * Try Cumana style partitions - sector 6 contains ADFS boot block
     * with pointer to next 'drive'.
     *
     * There are unknowns in this code - is the 'cylinder number' of the
     * next partition relative to the start of this one - I'm assuming
     * it is.
     *
     * Also, which ID did Cumana use?
     *
     * This is totally unfinished, and will require more work to get it
     * going. Hence it is totally untested.
     */
    do {
        struct adfs_discrecord *dr;
        unsigned int nr_sects;

        data = read_part_sector(state, start_blk * 2 + 6, &sect);
        if (!data)
            return -1;

        if (slot == state->limit)
            break;

        dr = adfs_partition(state, name, data, first_sector, slot++);
        if (!dr)
            break;

        name = NULL;

        nr_sects = (data[0x1fd] + (data[0x1fe] << 8)) *
               (dr->heads + (dr->lowsector & 0x40 ? 1 : 0)) *
               dr->secspertrack;

        if (!nr_sects)
            break;

        first = 0;
        first_sector += nr_sects;
        start_blk += nr_sects >> (BLOCK_SIZE_BITS - 9);
        nr_sects = 0; /* hmm - should be partition size */

        switch (data[0x1fc] & 15) {
        case 0: /* No partition / ADFS? */
            break;

#ifdef CONFIG_ACORN_PARTITION_RISCIX
        case PARTITION_RISCIX_SCSI:
            /* RISCiX - we don't know how to find the next one. */
            slot = riscix_partition(state, first_sector, slot,
                        nr_sects);
            break;
#endif

        case PARTITION_LINUX:
            slot = linux_partition(state, first_sector, slot,
                           nr_sects);
            break;
        }
        put_dev_sector(sect);
        if (slot == -1)
            return -1;
    } while (1);
    put_dev_sector(sect);
    return first ? 0 : 1;
}
#endif

#ifdef CONFIG_ACORN_PARTITION_ADFS
/*
 * Purpose: allocate ADFS partitions.
 *
 * Params : hd      - pointer to gendisk structure to store partition info.
 *      dev     - device number to access.
 *
 * Returns: -1 on error, 0 for no ADFS boot sector, 1 for ok.
 *
 * Alloc  : hda  = whole drive
 *      hda1 = ADFS partition on first drive.
 *      hda2 = non-ADFS partition.
 */
int adfspart_check_ADFS(struct parsed_partitions *state)
{
    unsigned long start_sect, nr_sects, sectscyl, heads;
    Sector sect;
    unsigned char *data;
    struct adfs_discrecord *dr;
    unsigned char id;
    int slot = 1;

    data = read_part_sector(state, 6, &sect);
    if (!data)
        return -1;

    dr = adfs_partition(state, "ADFS", data, 0, slot++);
    if (!dr) {
        put_dev_sector(sect);
            return 0;
    }

    heads = dr->heads + ((dr->lowsector >> 6) & 1);
    sectscyl = dr->secspertrack * heads;
    start_sect = ((data[0x1fe] << 8) + data[0x1fd]) * sectscyl;
    id = data[0x1fc] & 15;
    put_dev_sector(sect);

    /*
     * Work out start of non-adfs partition.
     */
    nr_sects = (state->bdev->bd_inode->i_size >> 9) - start_sect;

    if (start_sect) {
        switch (id) {
#ifdef CONFIG_ACORN_PARTITION_RISCIX
        case PARTITION_RISCIX_SCSI:
        case PARTITION_RISCIX_MFM:
            slot = riscix_partition(state, start_sect, slot,
                        nr_sects);
            break;
#endif

        case PARTITION_LINUX:
            slot = linux_partition(state, start_sect, slot,
                           nr_sects);
            break;
        }
    }
    strlcat(state->pp_buf, "\n", PAGE_SIZE);
    return 1;
}
#endif

#ifdef CONFIG_ACORN_PARTITION_ICS

struct ics_part {
    __le32 start;
    __le32 size;
};

static int adfspart_check_ICSLinux(struct parsed_partitions *state,
                   unsigned long block)
{
    Sector sect;
    unsigned char *data = read_part_sector(state, block, &sect);
    int result = 0;

    if (data) {
        if (memcmp(data, "LinuxPart", 9) == 0)
            result = 1;
        put_dev_sector(sect);
    }

    return result;
}

/*
 * Check for a valid ICS partition using the checksum.
 */
static inline int valid_ics_sector(const unsigned char *data)
{
    unsigned long sum;
    int i;

    for (i = 0, sum = 0x50617274; i < 508; i++)
        sum += data[i];

    sum -= le32_to_cpu(*(__le32 *)(&data[508]));

    return sum == 0;
}

/*
 * Purpose: allocate ICS partitions.
 * Params : hd      - pointer to gendisk structure to store partition info.
 *      dev     - device number to access.
 * Returns: -1 on error, 0 for no ICS table, 1 for partitions ok.
 * Alloc  : hda  = whole drive
 *      hda1 = ADFS partition 0 on first drive.
 *      hda2 = ADFS partition 1 on first drive.
 *      ..etc..
 */
int adfspart_check_ICS(struct parsed_partitions *state)
{
    const unsigned char *data;
    const struct ics_part *p;
    int slot;
    Sector sect;

    /*
     * Try ICS style partitions - sector 0 contains partition info.
     */
    data = read_part_sector(state, 0, &sect);
    if (!data)
            return -1;

    if (!valid_ics_sector(data)) {
            put_dev_sector(sect);
        return 0;
    }

    strlcat(state->pp_buf, " [ICS]", PAGE_SIZE);

    for (slot = 1, p = (const struct ics_part *)data; p->size; p++) {
        u32 start = le32_to_cpu(p->start);
        s32 size = le32_to_cpu(p->size); /* yes, it's signed. */

        if (slot == state->limit)
            break;

        /*
         * Negative sizes tell the RISC OS ICS driver to ignore
         * this partition - in effect it says that this does not
         * contain an ADFS filesystem.
         */
        if (size < 0) {
            size = -size;

            /*
             * Our own extension - We use the first sector
             * of the partition to identify what type this
             * partition is.  We must not make this visible
             * to the filesystem.
             */
            if (size > 1 && adfspart_check_ICSLinux(state, start)) {
                start += 1;
                size -= 1;
            }
        }

        if (size)
            put_partition(state, slot++, start, size);
    }

    put_dev_sector(sect);
    strlcat(state->pp_buf, "\n", PAGE_SIZE);
    return 1;
}
#endif

#ifdef CONFIG_ACORN_PARTITION_POWERTEC
struct ptec_part {
    __le32 unused1;
    __le32 unused2;
    __le32 start;
    __le32 size;
    __le32 unused5;
    char type[8];
};

static inline int valid_ptec_sector(const unsigned char *data)
{
    unsigned char checksum = 0x2a;
    int i;

    /*
     * If it looks like a PC/BIOS partition, then it
     * probably isn't PowerTec.
     */
    if (data[510] == 0x55 && data[511] == 0xaa)
        return 0;

    for (i = 0; i < 511; i++)
        checksum += data[i];

    return checksum == data[511];
}

/*
 * Purpose: allocate ICS partitions.
 * Params : hd      - pointer to gendisk structure to store partition info.
 *      dev     - device number to access.
 * Returns: -1 on error, 0 for no ICS table, 1 for partitions ok.
 * Alloc  : hda  = whole drive
 *      hda1 = ADFS partition 0 on first drive.
 *      hda2 = ADFS partition 1 on first drive.
 *      ..etc..
 */
int adfspart_check_POWERTEC(struct parsed_partitions *state)
{
    Sector sect;
    const unsigned char *data;
    const struct ptec_part *p;
    int slot = 1;
    int i;

    data = read_part_sector(state, 0, &sect);
    if (!data)
        return -1;

    if (!valid_ptec_sector(data)) {
        put_dev_sector(sect);
        return 0;
    }

    strlcat(state->pp_buf, " [POWERTEC]", PAGE_SIZE);

    for (i = 0, p = (const struct ptec_part *)data; i < 12; i++, p++) {
        u32 start = le32_to_cpu(p->start);
        u32 size = le32_to_cpu(p->size);

        if (size)
            put_partition(state, slot++, start, size);
    }

    put_dev_sector(sect);
    strlcat(state->pp_buf, "\n", PAGE_SIZE);
    return 1;
}
#endif

#ifdef CONFIG_ACORN_PARTITION_EESOX
struct eesox_part {
    char    magic[6];
    char    name[10];
    __le32  start;
    __le32  unused6;
    __le32  unused7;
    __le32  unused8;
};

/*
 * Guess who created this format?
 */
static const char eesox_name[] = {
    'N', 'e', 'i', 'l', ' ',
    'C', 'r', 'i', 't', 'c', 'h', 'e', 'l', 'l', ' ', ' '
};

/*
 * EESOX SCSI partition format.
 *
 * This is a goddamned awful partition format.  We don't seem to store
 * the size of the partition in this table, only the start addresses.
 *
 * There are two possibilities where the size comes from:
 *  1. The individual ADFS boot block entries that are placed on the disk.
 *  2. The start address of the next entry.
 */
int adfspart_check_EESOX(struct parsed_partitions *state)
{
    Sector sect;
    const unsigned char *data;
    unsigned char buffer[256];
    struct eesox_part *p;
    sector_t start = 0;
    int i, slot = 1;

    data = read_part_sector(state, 7, &sect);
    if (!data)
        return -1;

    /*
     * "Decrypt" the partition table.  God knows why...
     */
    for (i = 0; i < 256; i++)
        buffer[i] = data[i] ^ eesox_name[i & 15];

    put_dev_sector(sect);

    for (i = 0, p = (struct eesox_part *)buffer; i < 8; i++, p++) {
        sector_t next;

        if (memcmp(p->magic, "Eesox", 6))
            break;

        next = le32_to_cpu(p->start);
        if (i)
            put_partition(state, slot++, start, next - start);
        start = next;
    }

    if (i != 0) {
        sector_t size;

        size = get_capacity(state->bdev->bd_disk);
        put_partition(state, slot++, start, size - start);
        strlcat(state->pp_buf, "\n", PAGE_SIZE);
    }

    return i ? 1 : 0;
}
#endif