// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (c) 1996-2000 Russell King.
 *
 *  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