pcdisk.c

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/*
 *  FreeLoader
 *  Copyright (C) 1998-2003  Brian Palmer  <brianp@sginet.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <freeldr.h>
#include <debug.h>

DBG_DEFAULT_CHANNEL(DISK);

#include <pshpack2.h>
typedef struct
{
    UCHAR       PacketSize;             // 00h - Size of packet (10h or 18h)
    UCHAR       Reserved;               // 01h - Reserved (0)
    USHORT      LBABlockCount;          // 02h - Number of blocks to transfer (max 007Fh for Phoenix EDD)
    USHORT      TransferBufferOffset;   // 04h - Transfer buffer offset (seg:off)
    USHORT      TransferBufferSegment;  //       Transfer buffer segment (seg:off)
    ULONGLONG       LBAStartBlock;          // 08h - Starting absolute block number
    //ULONGLONG     TransferBuffer64;       // 10h - (EDD-3.0, optional) 64-bit flat address of transfer buffer
                                    //       used if DWORD at 04h is FFFFh:FFFFh
                                    //       Commented since some earlier BIOSes refuse to work with
                                    //       such extended structure
} I386_DISK_ADDRESS_PACKET, *PI386_DISK_ADDRESS_PACKET;
#include <poppack.h>

// FUNCTIONS

static BOOLEAN PcDiskResetController(UCHAR DriveNumber)
{
    REGS    RegsIn;
    REGS    RegsOut;

    WARN("PcDiskResetController(0x%x) DISK OPERATION FAILED -- RESETTING CONTROLLER\n", DriveNumber);

    // BIOS Int 13h, function 0 - Reset disk system
    // AH = 00h
    // DL = drive (if bit 7 is set both hard disks and floppy disks reset)
    // Return:
    // AH = status
    // CF clear if successful
    // CF set on error
    RegsIn.b.ah = 0x00;
    RegsIn.b.dl = DriveNumber;

    // Reset the disk controller
    Int386(0x13, &RegsIn, &RegsOut);

    return INT386_SUCCESS(RegsOut);
}

static BOOLEAN PcDiskReadLogicalSectorsLBA(UCHAR DriveNumber, ULONGLONG SectorNumber, ULONG SectorCount, PVOID Buffer)
{
    REGS                        RegsIn;
    REGS                        RegsOut;
    ULONG                           RetryCount;
    PI386_DISK_ADDRESS_PACKET   Packet = (PI386_DISK_ADDRESS_PACKET)(BIOSCALLBUFFER);

    TRACE("PcDiskReadLogicalSectorsLBA() DriveNumber: 0x%x SectorNumber: %I64d SectorCount: %d Buffer: 0x%x\n", DriveNumber, SectorNumber, SectorCount, Buffer);
    ASSERT(((ULONG_PTR)Buffer) <= 0xFFFFF);

    // BIOS int 0x13, function 42h - IBM/MS INT 13 Extensions - EXTENDED READ
    RegsIn.b.ah = 0x42;                 // Subfunction 42h
    RegsIn.b.dl = DriveNumber;          // Drive number in DL (0 - floppy, 0x80 - harddisk)
    RegsIn.x.ds = BIOSCALLBUFSEGMENT;   // DS:SI -> disk address packet
    RegsIn.w.si = BIOSCALLBUFOFFSET;

    // Setup disk address packet
    RtlZeroMemory(Packet, sizeof(I386_DISK_ADDRESS_PACKET));
    Packet->PacketSize = sizeof(I386_DISK_ADDRESS_PACKET);
    Packet->Reserved = 0;
    Packet->LBABlockCount = (USHORT)SectorCount;
    ASSERT(Packet->LBABlockCount == SectorCount);
    Packet->TransferBufferOffset = ((ULONG_PTR)Buffer) & 0x0F;
    Packet->TransferBufferSegment = (USHORT)(((ULONG_PTR)Buffer) >> 4);
    Packet->LBAStartBlock = SectorNumber;

    // BIOS int 0x13, function 42h - IBM/MS INT 13 Extensions - EXTENDED READ
    // Return:
    // CF clear if successful
    // AH = 00h
    // CF set on error
    // AH = error code
    // disk address packet's block count field set to the
    // number of blocks successfully transferred

    // Retry 3 times
    for (RetryCount=0; RetryCount<3; RetryCount++)
    {
        Int386(0x13, &RegsIn, &RegsOut);

        // If it worked return TRUE
        if (INT386_SUCCESS(RegsOut))
        {
            return TRUE;
        }
        // If it was a corrected ECC error then the data is still good
        else if (RegsOut.b.ah == 0x11)
        {
            return TRUE;
        }
        // If it failed the do the next retry
        else
        {
            PcDiskResetController(DriveNumber);

            continue;
        }
    }

    // If we get here then the read failed
    ERR("Disk Read Failed in LBA mode: %x (DriveNumber: 0x%x SectorNumber: %I64d SectorCount: %d)\n", RegsOut.b.ah, DriveNumber, SectorNumber, SectorCount);

    return FALSE;
}

static BOOLEAN PcDiskReadLogicalSectorsCHS(UCHAR DriveNumber, ULONGLONG SectorNumber, ULONG SectorCount, PVOID Buffer)
{
    UCHAR           PhysicalSector;
    UCHAR           PhysicalHead;
    ULONG           PhysicalTrack;
    GEOMETRY    DriveGeometry;
    ULONG           NumberOfSectorsToRead;
    REGS        RegsIn;
    REGS        RegsOut;
    ULONG           RetryCount;

    TRACE("PcDiskReadLogicalSectorsCHS()\n");

    //
    // Get the drive geometry
    //
    if (!MachDiskGetDriveGeometry(DriveNumber, &DriveGeometry) ||
        DriveGeometry.Sectors == 0 ||
        DriveGeometry.Heads == 0)
    {
        return FALSE;
    }

    while (SectorCount)
    {

        //
        // Calculate the physical disk offsets
        // Note: DriveGeometry.Sectors < 64
        //
        PhysicalSector = 1 + (UCHAR)(SectorNumber % DriveGeometry.Sectors);
        PhysicalHead = (UCHAR)((SectorNumber / DriveGeometry.Sectors) % DriveGeometry.Heads);
        PhysicalTrack = (ULONG)((SectorNumber / DriveGeometry.Sectors) / DriveGeometry.Heads);

        //
        // Calculate how many sectors we need to read this round
        //
        if (PhysicalSector > 1)
        {
            if (SectorCount >= (DriveGeometry.Sectors - (PhysicalSector - 1)))
                NumberOfSectorsToRead = (DriveGeometry.Sectors - (PhysicalSector - 1));
            else
                NumberOfSectorsToRead = SectorCount;
        }
        else
        {
            if (SectorCount >= DriveGeometry.Sectors)
                NumberOfSectorsToRead = DriveGeometry.Sectors;
            else
                NumberOfSectorsToRead = SectorCount;
        }

        //
        // Make sure the read is within the geometry boundaries
        //
        if ((PhysicalHead >= DriveGeometry.Heads) ||
            (PhysicalTrack >= DriveGeometry.Cylinders) ||
            ((NumberOfSectorsToRead + PhysicalSector) > (DriveGeometry.Sectors + 1)) ||
            (PhysicalSector > DriveGeometry.Sectors))
        {
            DiskError("Disk read exceeds drive geometry limits.", 0);
            return FALSE;
        }

        // BIOS Int 13h, function 2 - Read Disk Sectors
        // AH = 02h
        // AL = number of sectors to read (must be nonzero)
        // CH = low eight bits of cylinder number
        // CL = sector number 1-63 (bits 0-5)
        //      high two bits of cylinder (bits 6-7, hard disk only)
        // DH = head number
        // DL = drive number (bit 7 set for hard disk)
        // ES:BX -> data buffer
        // Return:
        // CF set on error
        // if AH = 11h (corrected ECC error), AL = burst length
        // CF clear if successful
        // AH = status
        // AL = number of sectors transferred
        //  (only valid if CF set for some BIOSes)
        RegsIn.b.ah = 0x02;
        RegsIn.b.al = (UCHAR)NumberOfSectorsToRead;
        RegsIn.b.ch = (PhysicalTrack & 0xFF);
        RegsIn.b.cl = (UCHAR)(PhysicalSector + ((PhysicalTrack & 0x300) >> 2));
        RegsIn.b.dh = PhysicalHead;
        RegsIn.b.dl = DriveNumber;
        RegsIn.w.es = (USHORT)(((ULONG_PTR)Buffer) >> 4);
        RegsIn.w.bx = ((ULONG_PTR)Buffer) & 0x0F;

        //
        // Perform the read
        // Retry 3 times
        //
        for (RetryCount=0; RetryCount<3; RetryCount++)
        {
            Int386(0x13, &RegsIn, &RegsOut);

            // If it worked break out
            if (INT386_SUCCESS(RegsOut))
            {
                break;
            }
            // If it was a corrected ECC error then the data is still good
            else if (RegsOut.b.ah == 0x11)
            {
                break;
            }
            // If it failed the do the next retry
            else
            {
                PcDiskResetController(DriveNumber);

                continue;
            }
        }

        // If we retried 3 times then fail
        if (RetryCount >= 3)
        {
            ERR("Disk Read Failed in CHS mode, after retrying 3 times: %x\n", RegsOut.b.ah);
            return FALSE;
        }

        // I have learned that not all bioses return
        // the sector read count in the AL register (at least mine doesn't)
        // even if the sectors were read correctly. So instead
        // of checking the sector read count we will rely solely
        // on the carry flag being set on error

        Buffer = (PVOID)((ULONG_PTR)Buffer + (NumberOfSectorsToRead * DriveGeometry.BytesPerSector));
        SectorCount -= NumberOfSectorsToRead;
        SectorNumber += NumberOfSectorsToRead;
    }

    return TRUE;
}

BOOLEAN PcDiskReadLogicalSectors(UCHAR DriveNumber, ULONGLONG SectorNumber, ULONG SectorCount, PVOID Buffer)
{
    BOOLEAN ExtensionsSupported;

    TRACE("PcDiskReadLogicalSectors() DriveNumber: 0x%x SectorNumber: %I64d SectorCount: %d Buffer: 0x%x\n", DriveNumber, SectorNumber, SectorCount, Buffer);

    //
    // Check to see if it is a fixed disk drive
    // If so then check to see if Int13 extensions work
    // If they do then use them, otherwise default back to BIOS calls
    //
    ExtensionsSupported = DiskInt13ExtensionsSupported(DriveNumber);

    if ((DriveNumber >= 0x80) && ExtensionsSupported)
    {
        TRACE("Using Int 13 Extensions for read. DiskInt13ExtensionsSupported(%d) = %s\n", DriveNumber, ExtensionsSupported ? "TRUE" : "FALSE");

        //
        // LBA is easy, nothing to calculate
        // Just do the read
        //
        return PcDiskReadLogicalSectorsLBA(DriveNumber, SectorNumber, SectorCount, Buffer);
    }
    else
    {
        // LBA is not supported default to the CHS calls
        return PcDiskReadLogicalSectorsCHS(DriveNumber, SectorNumber, SectorCount, Buffer);
    }

    return TRUE;
}

BOOLEAN
PcDiskGetDriveGeometry(UCHAR DriveNumber, PGEOMETRY Geometry)
{
  EXTENDED_GEOMETRY ExtGeometry;
  REGS RegsIn;
  REGS RegsOut;
  ULONG Cylinders;

  TRACE("DiskGetDriveGeometry()\n");

  /* Try to get the extended geometry first */
  ExtGeometry.Size = sizeof(EXTENDED_GEOMETRY);
  if (DiskGetExtendedDriveParameters(DriveNumber, &ExtGeometry, ExtGeometry.Size))
  {
    Geometry->Cylinders = ExtGeometry.Cylinders;
    Geometry->Heads = ExtGeometry.Heads;
    Geometry->Sectors = ExtGeometry.SectorsPerTrack;
    Geometry->BytesPerSector = ExtGeometry.BytesPerSector;

    return TRUE;
  }

  /* BIOS Int 13h, function 08h - Get drive parameters
   * AH = 08h
   * DL = drive (bit 7 set for hard disk)
   * ES:DI = 0000h:0000h to guard against BIOS bugs
   * Return:
   * CF set on error
   * AH = status (07h)
   * CF clear if successful
   * AH = 00h
   * AL = 00h on at least some BIOSes
   * BL = drive type (AT/PS2 floppies only)
   * CH = low eight bits of maximum cylinder number
   * CL = maximum sector number (bits 5-0)
   *      high two bits of maximum cylinder number (bits 7-6)
   * DH = maximum head number
   * DL = number of drives
   * ES:DI -> drive parameter table (floppies only)
   */
  RegsIn.b.ah = 0x08;
  RegsIn.b.dl = DriveNumber;
  RegsIn.w.es = 0x0000;
  RegsIn.w.di = 0x0000;

  /* Get drive parameters */
  Int386(0x13, &RegsIn, &RegsOut);

  if (! INT386_SUCCESS(RegsOut))
    {
      return FALSE;
    }

  Cylinders = (RegsOut.b.cl & 0xC0) << 2;
  Cylinders += RegsOut.b.ch;
  Cylinders++;
  Geometry->Cylinders = Cylinders;
  Geometry->Heads = RegsOut.b.dh + 1;
  Geometry->Sectors = RegsOut.b.cl & 0x3F;
  Geometry->BytesPerSector = 512;            /* Just assume 512 bytes per sector */

  return TRUE;
}

ULONG
PcDiskGetCacheableBlockCount(UCHAR DriveNumber)
{
  GEOMETRY  Geometry;

  /* If LBA is supported then the block size will be 64 sectors (32k)
   * If not then the block size is the size of one track */
  if (DiskInt13ExtensionsSupported(DriveNumber))
    {
      return 64;
    }
  /* Get the disk geometry
   * If this fails then we will just return 1 sector to be safe */
  else if (! PcDiskGetDriveGeometry(DriveNumber, &Geometry))
    {
      return 1;
    }
  else
    {
      return Geometry.Sectors;
    }
}

BOOLEAN
PcDiskGetBootPath(char *BootPath, unsigned Size)
{
  if (PxeInit())
    {
      strcpy(BootPath, "net(0)");
      return 0;
    }
  return DiskGetBootPath(BootPath, Size);
}

/* EOF */