src/cdrom.c

// Support for booting from cdroms (the "El Torito" spec).
//
// Copyright (C) 2008,2009  Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002  MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU LGPLv3 license.

#include "disk.h" // cdrom_13
#include "util.h" // memset
#include "bregs.h" // struct bregs
#include "biosvar.h" // GET_EBDA
#include "ata.h" // ATA_CMD_REQUEST_SENSE


/****************************************************************
 * CD emulation
 ****************************************************************/

static int
cdemu_read(struct disk_op_s *op)
{
    u16 ebda_seg = get_ebda_seg();
    struct drive_s *drive_g = GET_EBDA2(ebda_seg, cdemu.emulated_drive);
    struct disk_op_s dop;
    dop.drive_g = drive_g;
    dop.command = op->command;
    dop.lba = GET_EBDA2(ebda_seg, cdemu.ilba) + op->lba / 4;

    int count = op->count;
    op->count = 0;
    u8 *cdbuf_far = (void*)offsetof(struct extended_bios_data_area_s, cdemu_buf);

    if (op->lba & 3) {
        // Partial read of first block.
        dop.count = 1;
        dop.buf_fl = MAKE_FLATPTR(ebda_seg, cdbuf_far);
        int ret = process_op(&dop);
        if (ret)
            return ret;
        u8 thiscount = 4 - (op->lba & 3);
        if (thiscount > count)
            thiscount = count;
        count -= thiscount;
        memcpy_far(FLATPTR_TO_SEG(op->buf_fl)
                   , (void*)FLATPTR_TO_OFFSET(op->buf_fl)
                   , ebda_seg, cdbuf_far + (op->lba & 3) * 512
                   , thiscount * 512);
        op->buf_fl += thiscount * 512;
        op->count += thiscount;
        dop.lba++;
    }

    if (count > 3) {
        // Read n number of regular blocks.
        dop.count = count / 4;
        dop.buf_fl = op->buf_fl;
        int ret = process_op(&dop);
        op->count += dop.count * 4;
        if (ret)
            return ret;
        u8 thiscount = count & ~3;
        count &= 3;
        op->buf_fl += thiscount * 512;
        dop.lba += thiscount / 4;
    }

    if (count) {
        // Partial read on last block.
        dop.count = 1;
        dop.buf_fl = MAKE_FLATPTR(ebda_seg, cdbuf_far);
        int ret = process_op(&dop);
        if (ret)
            return ret;
        u8 thiscount = count;
        memcpy_far(FLATPTR_TO_SEG(op->buf_fl)
                   , (void*)FLATPTR_TO_OFFSET(op->buf_fl)
                   , ebda_seg, cdbuf_far, thiscount * 512);
        op->count += thiscount;
    }

    return DISK_RET_SUCCESS;
}

int
process_cdemu_op(struct disk_op_s *op)
{
    if (!CONFIG_CDROM_EMU)
        return 0;

    switch (op->command) {
    case CMD_READ:
        return cdemu_read(op);
    case CMD_WRITE:
    case CMD_FORMAT:
        return DISK_RET_EWRITEPROTECT;
    case CMD_VERIFY:
    case CMD_RESET:
    case CMD_SEEK:
    case CMD_ISREADY:
        return DISK_RET_SUCCESS;
    default:
        op->count = 0;
        return DISK_RET_EPARAM;
    }
}

struct drive_s *cdemu_drive VAR16VISIBLE;

void
cdemu_setup()
{
    if (!CONFIG_CDROM_EMU)
        return;

    struct drive_s *drive_g = allocDrive();
    if (!drive_g) {
        cdemu_drive = NULL;
        return;
    }
    cdemu_drive = ADJUST_GLOBAL_PTR(drive_g);
    drive_g->type = DTYPE_CDEMU;
    drive_g->blksize = DISK_SECTOR_SIZE;
    drive_g->sectors = (u64)-1;
}

struct eltorito_s {
    u8 size;
    u8 media;
    u8 emulated_drive;
    u8 controller_index;
    u32 ilba;
    u16 device_spec;
    u16 buffer_segment;
    u16 load_segment;
    u16 sector_count;
    u8 cylinders;
    u8 sectors;
    u8 heads;
};

#define SET_INT13ET(regs,var,val)                                      \
    SET_FARVAR((regs)->ds, ((struct eltorito_s*)((regs)->si+0))->var, (val))

// ElTorito - Terminate disk emu
void
cdemu_134b(struct bregs *regs)
{
    // FIXME ElTorito Hardcoded
    u16 ebda_seg = get_ebda_seg();
    SET_INT13ET(regs, size, 0x13);
    SET_INT13ET(regs, media, GET_EBDA2(ebda_seg, cdemu.media));
    SET_INT13ET(regs, emulated_drive
                , GET_EBDA2(ebda_seg, cdemu.emulated_extdrive));
    struct drive_s *drive_g = GET_EBDA2(ebda_seg, cdemu.emulated_drive);
    u8 cntl_id = GET_GLOBAL(drive_g->cntl_id);
    SET_INT13ET(regs, controller_index, cntl_id / 2);
    SET_INT13ET(regs, device_spec, cntl_id % 2);
    SET_INT13ET(regs, ilba, GET_EBDA2(ebda_seg, cdemu.ilba));
    SET_INT13ET(regs, buffer_segment, GET_EBDA2(ebda_seg, cdemu.buffer_segment));
    SET_INT13ET(regs, load_segment, GET_EBDA2(ebda_seg, cdemu.load_segment));
    SET_INT13ET(regs, sector_count, GET_EBDA2(ebda_seg, cdemu.sector_count));
    SET_INT13ET(regs, cylinders, GET_EBDA2(ebda_seg, cdemu.lchs.cylinders));
    SET_INT13ET(regs, sectors, GET_EBDA2(ebda_seg, cdemu.lchs.spt));
    SET_INT13ET(regs, heads, GET_EBDA2(ebda_seg, cdemu.lchs.heads));

    // If we have to terminate emulation
    if (regs->al == 0x00) {
        // FIXME ElTorito Various. Should be handled accordingly to spec
        SET_EBDA2(ebda_seg, cdemu.active, 0x00); // bye bye
    }

    disk_ret(regs, DISK_RET_SUCCESS);
}


/****************************************************************
 * CD booting
 ****************************************************************/

// Request SENSE
static int
atapi_get_sense(struct drive_s *drive_g, u8 *asc, u8 *ascq)
{
    u8 atacmd[12], buffer[18];
    memset(atacmd, 0, sizeof(atacmd));
    atacmd[0] = ATA_CMD_REQUEST_SENSE;
    atacmd[4] = sizeof(buffer);
    int ret = ata_cmd_packet(drive_g, atacmd, sizeof(atacmd), sizeof(buffer)
                             , MAKE_FLATPTR(GET_SEG(SS), buffer));
    if (ret)
        return ret;

    *asc = buffer[12];
    *ascq = buffer[13];

    return 0;
}

// Request capacity
static int
atapi_read_capacity(struct drive_s *drive_g, u32 *blksize, u32 *sectors)
{
    u8 packet[12], buf[8];
    memset(packet, 0, sizeof(packet));
    packet[0] = 0x25; /* READ CAPACITY */
    int ret = ata_cmd_packet(drive_g, packet, sizeof(packet), sizeof(buf)
                             , MAKE_FLATPTR(GET_SEG(SS), buf));
    if (ret)
        return ret;

    *blksize = (((u32)buf[4] << 24) | ((u32)buf[5] << 16)
                | ((u32)buf[6] << 8) | ((u32)buf[7] << 0));
    *sectors = (((u32)buf[0] << 24) | ((u32)buf[1] << 16)
                | ((u32)buf[2] << 8) | ((u32)buf[3] << 0));

    return 0;
}

static int
atapi_is_ready(struct drive_s *drive_g)
{
    dprintf(6, "atapi_is_ready (drive=%p)\n", drive_g);

    /* Retry READ CAPACITY for 5 seconds unless MEDIUM NOT PRESENT is
     * reported by the device.  If the device reports "IN PROGRESS",
     * 30 seconds is added. */
    u32 blksize, sectors;
    int in_progress = 0;
    u64 end = calc_future_tsc(5000);
    for (;;) {
        if (check_time(end)) {
            dprintf(1, "read capacity failed\n");
            return -1;
        }

        int ret = atapi_read_capacity(drive_g, &blksize, &sectors);
        if (!ret)
            // Success
            break;

        u8 asc, ascq;
        ret = atapi_get_sense(drive_g, &asc, &ascq);
        if (ret)
            // Error - retry.
            continue;

        // Sense succeeded.
        if (asc == 0x3a) { /* MEDIUM NOT PRESENT */
            dprintf(1, "Device reports MEDIUM NOT PRESENT\n");
            return -1;
        }

        if (asc == 0x04 && ascq == 0x01 && !in_progress) {
            /* IN PROGRESS OF BECOMING READY */
            printf("Waiting for device to detect medium... ");
            /* Allow 30 seconds more */
            end = calc_future_tsc(30000);
            in_progress = 1;
        }
    }

    if (blksize != GET_GLOBAL(drive_g->blksize)) {
        printf("Unsupported sector size %u\n", blksize);
        return -1;
    }

    dprintf(6, "sectors=%u\n", sectors);
    printf("%dMB medium detected\n", sectors>>(20-11));
    return 0;
}

int
cdrom_boot(int cdid)
{
    struct drive_s *drive_g = getDrive(EXTTYPE_CD, cdid);
    if (!drive_g)
        return 1;

    int ret = atapi_is_ready(drive_g);
    if (ret)
        dprintf(1, "atapi_is_ready returned %d\n", ret);

    // Read the Boot Record Volume Descriptor
    u8 buffer[2048];
    struct disk_op_s dop;
    memset(&dop, 0, sizeof(dop));
    dop.drive_g = drive_g;
    dop.lba = 0x11;
    dop.count = 1;
    dop.buf_fl = MAKE_FLATPTR(GET_SEG(SS), buffer);
    ret = cdrom_read(&dop);
    if (ret)
        return 3;

    // Validity checks
    if (buffer[0])
        return 4;
    if (strcmp((char*)&buffer[1], "CD001\001EL TORITO SPECIFICATION") != 0)
        return 5;

    // ok, now we calculate the Boot catalog address
    u32 lba = *(u32*)&buffer[0x47];

    // And we read the Boot Catalog
    dop.lba = lba;
    ret = cdrom_read(&dop);
    if (ret)
        return 7;

    // Validation entry
    if (buffer[0x00] != 0x01)
        return 8;   // Header
    if (buffer[0x01] != 0x00)
        return 9;   // Platform
    if (buffer[0x1E] != 0x55)
        return 10;  // key 1
    if (buffer[0x1F] != 0xAA)
        return 10;  // key 2

    // Initial/Default Entry
    if (buffer[0x20] != 0x88)
        return 11; // Bootable

    u16 ebda_seg = get_ebda_seg();
    u8 media = buffer[0x21];
    SET_EBDA2(ebda_seg, cdemu.media, media);

    SET_EBDA2(ebda_seg, cdemu.emulated_drive, ADJUST_GLOBAL_PTR(drive_g));

    u16 boot_segment = *(u16*)&buffer[0x22];
    if (!boot_segment)
        boot_segment = 0x07C0;
    SET_EBDA2(ebda_seg, cdemu.load_segment, boot_segment);
    SET_EBDA2(ebda_seg, cdemu.buffer_segment, 0x0000);

    u16 nbsectors = *(u16*)&buffer[0x26];
    SET_EBDA2(ebda_seg, cdemu.sector_count, nbsectors);

    lba = *(u32*)&buffer[0x28];
    SET_EBDA2(ebda_seg, cdemu.ilba, lba);

    // And we read the image in memory
    dop.lba = lba;
    dop.count = DIV_ROUND_UP(nbsectors, 4);
    dop.buf_fl = MAKE_FLATPTR(boot_segment, 0);
    ret = cdrom_read(&dop);
    if (ret)
        return 12;

    if (media == 0) {
        // No emulation requested - return success.
        SET_EBDA2(ebda_seg, cdemu.emulated_extdrive, EXTSTART_CD + cdid);
        return 0;
    }

    // Emulation of a floppy/harddisk requested
    if (! CONFIG_CDROM_EMU || !cdemu_drive)
        return 13;

    // Set emulated drive id and increase bios installed hardware
    // number of devices
    if (media < 4) {
        // Floppy emulation
        SET_EBDA2(ebda_seg, cdemu.emulated_extdrive, 0x00);
        SETBITS_BDA(equipment_list_flags, 0x41);

        switch (media) {
        case 0x01:  // 1.2M floppy
            SET_EBDA2(ebda_seg, cdemu.lchs.spt, 15);
            SET_EBDA2(ebda_seg, cdemu.lchs.cylinders, 80);
            SET_EBDA2(ebda_seg, cdemu.lchs.heads, 2);
            break;
        case 0x02:  // 1.44M floppy
            SET_EBDA2(ebda_seg, cdemu.lchs.spt, 18);
            SET_EBDA2(ebda_seg, cdemu.lchs.cylinders, 80);
            SET_EBDA2(ebda_seg, cdemu.lchs.heads, 2);
            break;
        case 0x03:  // 2.88M floppy
            SET_EBDA2(ebda_seg, cdemu.lchs.spt, 36);
            SET_EBDA2(ebda_seg, cdemu.lchs.cylinders, 80);
            SET_EBDA2(ebda_seg, cdemu.lchs.heads, 2);
            break;
        }
    } else {
        // Harddrive emulation
        SET_EBDA2(ebda_seg, cdemu.emulated_extdrive, 0x80);
        SET_BDA(hdcount, GET_BDA(hdcount) + 1);

        // Peak at partition table to get chs.
        struct mbr_s *mbr = (void*)0;
        u8 sptcyl = GET_FARVAR(boot_segment, mbr->partitions[0].last.sptcyl);
        u8 cyllow = GET_FARVAR(boot_segment, mbr->partitions[0].last.cyllow);
        u8 heads = GET_FARVAR(boot_segment, mbr->partitions[0].last.heads);

        SET_EBDA2(ebda_seg, cdemu.lchs.spt, sptcyl & 0x3f);
        SET_EBDA2(ebda_seg, cdemu.lchs.cylinders
                  , ((sptcyl<<2)&0x300) + cyllow + 1);
        SET_EBDA2(ebda_seg, cdemu.lchs.heads, heads + 1);
    }

    // everything is ok, so from now on, the emulation is active
    SET_EBDA2(ebda_seg, cdemu.active, 0x01);
    dprintf(6, "cdemu media=%d\n", media);

    return 0;
}