source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm@ 603

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for detecting drive for the BIOS.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
;
; 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.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Detects all IDE hard disks to be controlled by this BIOS.
;
; DetectDrives_FromAllIDEControllers
;   Parameters:
;       DS:     RAMVARS segment
;       ES:     BDA segment (zero)
;   Returns:
;       Nothing
;   Corrupts registers:
;       All (not segments)
;--------------------------------------------------------------------
DetectDrives_FromAllIDEControllers:
    call    RamVars_GetIdeControllerCountToCX
    mov     bp, ROMVARS.ideVars0            ; CS:BP now points to first IDEVARS

.DriveDetectLoop:                           ; Loop through IDEVARS
    push    cx

    mov     cx, g_szDetectMaster
    mov     bh, MASK_DRVNHEAD_SET                               ; Select Master drive
    call    StartDetectionWithDriveSelectByteInBHandStringInCX  ; Detect and create DPT + BOOTNFO

    mov     cx, g_szDetectSlave
    mov     bh, MASK_DRVNHEAD_SET | FLG_DRVNHEAD_DRV
    call    StartDetectionWithDriveSelectByteInBHandStringInCX

%ifdef MODULE_HOTKEYS
%ifdef MODULE_SERIAL
    ; This is only needed for hotkey F6 (ComDtct) to work
    call    ScanHotkeysFromKeyBufferAndStoreToBootvars          ; Done here while CX is still protected
%endif
%endif

    pop     cx

    add     bp, BYTE IDEVARS_size           ; Point to next IDEVARS

%ifdef MODULE_SERIAL
    jcxz    .AddHardDisks                   ; Set to zero on .ideVarsSerialAuto iteration (if any)
%endif
    loop    .DriveDetectLoop

%ifdef MODULE_SERIAL
;----------------------------------------------------------------------
;
; if serial drive detected, do not scan (avoids duplicate drives and isn't needed - we already have a connection)
;
    call    FindDPT_ToDSDIforSerialDevice   ; Does not modify AX
    jnc     .AddHardDisks

    mov     bp, ROMVARS.ideVarsSerialAuto   ; Point to our special IDEVARS structure, just for serial scans

%ifdef MODULE_HOTKEYS
    cmp     al, COM_DETECT_HOTKEY_SCANCODE  ; Set by last call to ScanHotkeysFromKeyBufferAndStoreToBootvars above
    je      .DriveDetectLoop
%endif

    mov     al, [cs:ROMVARS.wFlags]         ; Configurator set to always scan?
    or      al, [es:BDA.bKBFlgs1]           ; Or, did the user hold down the ALT key?
    and     al, 8                           ; 8 = alt key depressed, same as FLG_ROMVARS_SERIAL_SCANDETECT
    jnz     .DriveDetectLoop
%endif ; MODULE_SERIAL

.AddHardDisks:
;----------------------------------------------------------------------
;
; Add in hard disks to BDA, finalize our Count and First variables
;
; Note that we perform the add to bHDCount and store bFirstDrv even if the count is zero.
; This is done because we use the value of .bFirstDrv to know how many drives were in the system
; at the time of boot, and to return that number on int13h/8h calls.  Because the count is zero,
; FindDPT_ForDriveNumber will not find any drives that are ours.
;

; Here we might want to replace BIOS configured drives with the ones we detected.
; Primary reason is to support dynamic overlay feature in the future. Second reason
; is a hack to get Windows 95 to load its built-in protected mode IDE driver.
;
; The Windows hack has two parts. First part is to try to alter CMOS address 12h as that
; is what Windows 95 driver reads to detect IDE drives. Altering is not possible on all
; systems since CMOS has a checksum but its location is not standardized. We will first
; try to detect valid checksum. If it succeeds, then it is safe to assume this system
; has compatible CMOS and we can alter it.
; If verify fails, we do the more dirty hack to zero BDA drive count. Then Windows 95 works
; as long as user has configured at least one drive in the BIOS setup.

%ifdef USE_AT   ; FLG_ROMVARS_IGNORE_MOTHERBOARD_DRIVES is for AT builds only
%ifdef MODULE_WIN95_CMOS_HACK
    mov     dl, HARD_DISK_TYPES
    call    CMOS_ReadFromIndexInDLtoAL
    test    al, 0F0h
    jnz     SHORT .ClearBdaDriveCount       ; CMOS byte 12h is ready for Windows 95
    call    CMOS_Verify10hTo2Dh             ; Can we modify CMOS?
    jnz     SHORT .ClearBdaDriveCount       ; Unsupported BIOS, use plan B

    ; Now we can alter CMOS location 12h. Award BIOS locks if we set drive 0 type to Fh
    ; (but accept changes to drive type 1). Windows 95 requires that the drive 0 type is
    ; non zero and ignores drive 1 type. So if we only set drive 1, then Award BIOS
    ; won't give problems but Windows 95 stays in MS-DOS compatibility mode.
    ;
    ; For Award BIOSes we could set the Drive 0 type to 1 and then clear the BDA drive count.
    ; So essentially we could automatically do what user needs to do manually to get Windows 95
    ; working on Award BIOSes. However, I think that should be left to do manually since
    ; there may be SCSI drives on the system or FLG_ROMVARS_IGNORE_MOTHERBOARD_DRIVES could
    ; be intentionally cleared and forcing the dummy drive might cause only trouble.

    ; Try to detect Award BIOS (Seems to work on a tested 128k BIOS so hopefully
    ; there will be no need to scan E000h segment)
    mov     cx, 65536 - 4
    mov     eax, 'Awar'                     ; Four characters should be enough
    mov     di, 0F000h                      ; Scan 64k starting from segment F000h
    mov     fs, di                          ; No need to preserve FS since we set it to zero soon when we boot
    xor     di, di
.ScanNextCharacters:
    cmp     [fs:di], eax
    je      SHORT .ClearBdaDriveCount       ; Award detected, cannot modify CMOS
    inc     di                              ; Increment offset by one character (not four)
    loop    .ScanNextCharacters

    ; Now it should be safe to write
    mov     dl, HARD_DISK_TYPES
    mov     al, 0F0h                        ; Drive 0 type 16...47 (supposed to be defined elsewhere in the CMOS)
    call    CMOS_WriteALtoIndexInDL
    call    CMOS_StoreNewChecksumFor10hto2Dh
.ClearBdaDriveCount:
%endif ; MODULE_WIN95_CMOS_HACK

    test    BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_IGNORE_MOTHERBOARD_DRIVES
    jz      SHORT .ContinueInitialization
    mov     BYTE [es:BDA.bHDCount], 0       ; Set hard disk count to zero
.ContinueInitialization:
%endif ; USE_AT

    mov     cx, [RAMVARS.wDrvCntAndFlopCnt] ; Our count of hard disks
    mov     al, [es:BDA.bHDCount]
    add     [es:BDA.bHDCount], cl           ; Add our drives to the system count
    or      al, 80h                         ; Or in hard disk flag
    mov     [RAMVARS.bFirstDrv], al         ; Store first drive number

.AddFloppies:
%ifdef MODULE_SERIAL_FLOPPY
;----------------------------------------------------------------------
;
; Add in any emulated serial floppy drives, finalize our packed Count and First variables
;
    dec     ch
    mov     al, ch
    js      SHORT .NoFloppies               ; If no drives are present, we store 0FFh

    call    FloppyDrive_GetCountFromBIOS_or_BDA

    push    ax

    add     al, ch                          ; Add our drives to existing drive count
    cmp     al, 3                           ; For BDA, max out at 4 drives (ours is zero based)
    jb      .MaxBDAFloppiesExceeded
    mov     al, 3
.MaxBDAFloppiesExceeded:
    eROR_IM al, 2                           ; move to bits 6-7
    inc     ax                              ; low order bit, indicating floppy drive exists

    mov     ah, 3Eh                         ; AND mask to AH (all bits set except floppy drive count/present)
    and     ah, [es:BDA.wEquipment]         ; Load Equipment WORD low byte and mask off drive number and drives present bit
    or      al, ah                          ; Or in new values
    mov     [es:BDA.wEquipment], al         ; and store

    mov     al, 1Eh                         ; BDA pointer to Floppy DPT
    mov     si, AH8h_FloppyDPT
    call    Interrupts_InstallHandlerToVectorInALFromCSSI

    pop     ax

    shr     ch, 1                           ; number of drives, 1 or 2 only, to CF flag (clear=1, set=2)
    eRCL_IM al, 1                           ; starting drive number in upper 7 bits, number of drives in low bit
.NoFloppies:
    mov     [RAMVARS.xlateVars+XLATEVARS.bFlopCntAndFirst], al
%endif
    ret

%ifndef CHECK_FOR_UNUSED_ENTRYPOINTS
    %if FLG_ROMVARS_SERIAL_SCANDETECT != 8
        %error "DetectDrives is currently coded to assume that FLG_ROMVARS_SERIAL_SCANDETECT is the same bit as the ALT key code in the BDA.  Changes in the code will be needed if these values are no longer the same."
    %endif
%endif


;--------------------------------------------------------------------
; StartDetectionWithDriveSelectByteInBHandStringInCX
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       CX:     Offset to "Master" or "Slave" string
;       CS:BP:  Ptr to IDEVARS for the drive
;       DS:     RAMVARS segment
;       ES:     Zero (BDA segment)
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BL, CX, DX, SI, DI
;--------------------------------------------------------------------
StartDetectionWithDriveSelectByteInBHandStringInCX:
    call    DetectPrint_StartDetectWithMasterOrSlaveStringInCXandIdeVarsInCSBP
    ; Fall to .ReadAtaInfoFromHardDisk


;--------------------------------------------------------------------
; .ReadAtaInfoFromHardDisk
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       DX:     Autodetected port (for devices that support autodetection)
;       CS:BP:  Ptr to IDEVARS for the drive
;       DS:     RAMVARS segment
;       ES:     Zero (BDA segment)
;   Returns:
;       CF:     Cleared if ATA-information read successfully
;               Set if any error
;   Corrupts registers:
;       AX, BL, CX, DX, SI, DI
;--------------------------------------------------------------------
.ReadAtaInfoFromHardDisk:
    mov     si, BOOTVARS.rgbAtaInfo         ; ES:SI now points to ATA info location
    push    es
    push    si
    push    dx
    push    bx
    call    Device_IdentifyToBufferInESSIwithDriveSelectByteInBH
    pop     bx
    pop     dx
    pop     si
    pop     es
    jnc     SHORT CreateBiosTablesForHardDisk
    ; Fall to .ReadAtapiInfoFromDrive

.ReadAtapiInfoFromDrive:                    ; Not yet implemented
    ;call   ReadAtapiInfoFromDrive          ; Assume CD-ROM
    ;jnc    SHORT _CreateBiosTablesForCDROM

    ;jmp    short DetectDrives_DriveNotFound
;;; fall-through instead of previous jmp instruction
;--------------------------------------------------------------------
; DetectDrives_DriveNotFound
;   Parameters:
;       Nothing
;   Returns:
;       CF:     Set (from DetectPrint_NullTerminatedStringFromCSSIandSetCF)
;   Corrupts registers:
;       AX, SI
;--------------------------------------------------------------------
DetectDrives_DriveNotFound:
    mov     si, g_szNotFound
    jmp     DetectPrint_NullTerminatedStringFromCSSIandSetCF


;--------------------------------------------------------------------
; CreateBiosTablesForHardDisk
;   Parameters:
;       BH:     Drive Select byte for Drive and Head Register
;       DX:     Autodetected port (for devices that support autodetection)
;       CS:BP:  Ptr to IDEVARS for the drive
;       ES:SI   Ptr to ATA information for the drive
;       DS:     RAMVARS segment
;       ES:     BDA segment
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
CreateBiosTablesForHardDisk:
%ifndef NO_ATAID_VALIDATION
    push    bx
    call    AtaID_VerifyFromESSI
    pop     bx
    jnz     SHORT DetectDrives_DriveNotFound
%endif
    call    CreateDPT_FromAtaInformation
    jc      SHORT DetectDrives_DriveNotFound
    call    DriveDetectInfo_CreateForHardDisk
    jmp     SHORT DetectPrint_DriveNameFromDrvDetectInfoInESBX