int13.h

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#ifndef INT13_H
#define INT13_H

/** @file
 *
 * INT 13 emulation
 *
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>
#include <gpxe/list.h>
#include <realmode.h>

struct block_device;

/**
 * @defgroup int13ops INT 13 operation codes
 * @{
 */

/** Reset disk system */
#define INT13_RESET                     0x00
/** Get status of last operation */
#define INT13_GET_LAST_STATUS           0x01
/** Read sectors */
#define INT13_READ_SECTORS              0x02
/** Write sectors */
#define INT13_WRITE_SECTORS             0x03
/** Get drive parameters */
#define INT13_GET_PARAMETERS            0x08
/** Get disk type */
#define INT13_GET_DISK_TYPE             0x15
/** Extensions installation check */
#define INT13_EXTENSION_CHECK           0x41
/** Extended read */
#define INT13_EXTENDED_READ             0x42
/** Extended write */
#define INT13_EXTENDED_WRITE            0x43
/** Get extended drive parameters */
#define INT13_GET_EXTENDED_PARAMETERS   0x48
/** Get CD-ROM status / terminate emulation */
#define INT13_CDROM_STATUS_TERMINATE    0x4b

/** @} */

/**
 * @defgroup int13status INT 13 status codes
 * @{
 */

/** Operation completed successfully */
#define INT13_STATUS_SUCCESS            0x00
/** Invalid function or parameter */
#define INT13_STATUS_INVALID            0x01
/** Read error */
#define INT13_STATUS_READ_ERROR         0x04
/** Write error */
#define INT13_STATUS_WRITE_ERROR        0xcc

/** @} */

/** Block size for non-extended INT 13 calls */
#define INT13_BLKSIZE 512

/** An INT 13 emulated drive */
struct int13_drive {
        /** List of all registered drives */
        struct list_head list;

        /** Underlying block device */
        struct block_device *blockdev;

        /** BIOS in-use drive number (0x80-0xff) */
        unsigned int drive;
        /** BIOS natural drive number (0x80-0xff)
         *
         * This is the drive number that would have been assigned by
         * 'naturally' appending the drive to the end of the BIOS
         * drive list.
         *
         * If the emulated drive replaces a preexisting drive, this is
         * the drive number that the preexisting drive gets remapped
         * to.
         */
        unsigned int natural_drive;

        /** Number of cylinders
         *
         * The cylinder number field in an INT 13 call is ten bits
         * wide, giving a maximum of 1024 cylinders.  Conventionally,
         * when the 7.8GB limit of a CHS address is exceeded, it is
         * the number of cylinders that is increased beyond the
         * addressable limit.
         */
        unsigned int cylinders;
        /** Number of heads
         *
         * The head number field in an INT 13 call is eight bits wide,
         * giving a maximum of 256 heads.  However, apparently all
         * versions of MS-DOS up to and including Win95 fail with 256
         * heads, so the maximum encountered in practice is 255.
         */
        unsigned int heads;
        /** Number of sectors per track
         *
         * The sector number field in an INT 13 call is six bits wide,
         * giving a maximum of 63 sectors, since sector numbering
         * (unlike head and cylinder numbering) starts at 1, not 0.
         */
        unsigned int sectors_per_track;

        /** Status of last operation */
        int last_status;
};

/** An INT 13 disk address packet */
struct int13_disk_address {
        /** Size of the packet, in bytes */
        uint8_t bufsize;
        /** Reserved, must be zero */
        uint8_t reserved;
        /** Block count */
        uint16_t count;
        /** Data buffer */
        struct segoff buffer;
        /** Starting block number */
        uint64_t lba;
        /** Data buffer (EDD-3.0 only) */
        uint64_t buffer_phys;
} __attribute__ (( packed ));

/** INT 13 disk parameters */
struct int13_disk_parameters {
        /** Size of this structure */
        uint16_t bufsize;
        /** Flags */
        uint16_t flags;
        /** Number of cylinders */
        uint32_t cylinders;
        /** Number of heads */
        uint32_t heads;
        /** Number of sectors per track */
        uint32_t sectors_per_track;
        /** Total number of sectors on drive */
        uint64_t sectors;
        /** Bytes per sector */
        uint16_t sector_size;
        
} __attribute__ (( packed ));

/**
 * @defgroup int13types INT 13 disk types
 * @{
 */

/** No such drive */
#define INT13_DISK_TYPE_NONE    0x00
/** Floppy without change-line support */
#define INT13_DISK_TYPE_FDD     0x01
/** Floppy with change-line support */
#define INT13_DISK_TYPE_FDD_CL  0x02
/** Hard disk */
#define INT13_DISK_TYPE_HDD     0x03

/** @} */

/**
 * @defgroup int13flags INT 13 disk parameter flags
 * @{
 */

/** DMA boundary errors handled transparently */
#define INT13_FL_DMA_TRANSPARENT 0x01
/** CHS information is valid */
#define INT13_FL_CHS_VALID       0x02
/** Removable drive */
#define INT13_FL_REMOVABLE       0x04
/** Write with verify supported */
#define INT13_FL_VERIFIABLE      0x08
/** Has change-line supported (valid only for removable drives) */
#define INT13_FL_CHANGE_LINE     0x10
/** Drive can be locked (valid only for removable drives) */
#define INT13_FL_LOCKABLE        0x20
/** CHS is max possible, not current media (valid only for removable drives) */
#define INT13_FL_CHS_MAX         0x40

/** @} */

/**
 * @defgroup int13exts INT 13 extension flags
 * @{
 */

/** Extended disk access functions supported */
#define INT13_EXTENSION_LINEAR          0x01
/** Removable drive functions supported */
#define INT13_EXTENSION_REMOVABLE       0x02
/** EDD functions supported */
#define INT13_EXTENSION_EDD             0x04

/** @} */

/**
 * @defgroup int13vers INT 13 extension versions
 * @{
 */

/** INT13 extensions version 1.x */
#define INT13_EXTENSION_VER_1_X         0x01
/** INT13 extensions version 2.0 (EDD-1.0) */
#define INT13_EXTENSION_VER_2_0         0x20
/** INT13 extensions version 2.1 (EDD-1.1) */
#define INT13_EXTENSION_VER_2_1         0x21
/** INT13 extensions version 3.0 (EDD-3.0) */
#define INT13_EXTENSION_VER_3_0         0x30

/** @} */ 

/** Bootable CD-ROM specification packet */
struct int13_cdrom_specification {
        /** Size of packet in bytes */
        uint8_t size;
        /** Boot media type */
        uint8_t media_type;
        /** Drive number */
        uint8_t drive;
        /** CD-ROM controller number */
        uint8_t controller;
        /** LBA of disk image to emulate */
        uint32_t lba;
        /** Device specification */
        uint16_t device;
        /** Segment of 3K buffer for caching CD-ROM reads */
        uint16_t cache_segment;
        /** Load segment for initial boot image */
        uint16_t load_segment;
        /** Number of 512-byte sectors to load */
        uint16_t load_sectors;
        /** Low 8 bits of cylinder number */
        uint8_t cyl;
        /** Sector number, plus high 2 bits of cylinder number */
        uint8_t cyl_sector;
        /** Head number */
        uint8_t head;
} __attribute__ (( packed ));

/** A C/H/S address within a partition table entry */
struct partition_chs {
        /** Head number */
        uint8_t head;
        /** Sector number, plus high 2 bits of cylinder number */
        uint8_t cyl_sector;
        /** Low 8 bits of cylinder number */
        uint8_t cyl;
} __attribute__ (( packed ));

#define PART_HEAD(chs) ( (chs).head )
#define PART_SECTOR(chs) ( (chs).cyl_sector & 0x3f )
#define PART_CYLINDER(chs) ( (chs).cyl | ( ( (chs).cyl_sector & 0xc0 ) << 2 ) )

/** A partition table entry within the MBR */
struct partition_table_entry {
        /** Bootable flag */
        uint8_t bootable;
        /** C/H/S start address */
        struct partition_chs chs_start;
        /** System indicator (partition type) */
        uint8_t type;
        /** C/H/S end address */
        struct partition_chs chs_end;
        /** Linear start address */
        uint32_t start;
        /** Linear length */
        uint32_t length;
} __attribute__ (( packed ));

/** A Master Boot Record */
struct master_boot_record {
        uint8_t pad[446];
        /** Partition table */
        struct partition_table_entry partitions[4];
        /** 0x55aa MBR signature */
        uint16_t signature;
} __attribute__ (( packed ));

extern void register_int13_drive ( struct int13_drive *drive );
extern void unregister_int13_drive ( struct int13_drive *drive );
extern int int13_boot ( unsigned int drive );

#endif /* INT13_H */