source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS_Configurator_v2/Src/FlashSST.asm @ 620

; Project name  :   XTIDE Universal BIOS Configurator v2
; Description   :   Functions for flashing SST flash devices.

;
; Created by Jayeson Lee-Steere
; Hereby placed into the public domain.
;

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; FlashSst_WithFlashvarsInDSSI
;   Parameters:
;       DS:BX:  Ptr to FLASHVARS
;   Returns:
;       Updated FLASHVARS in DS:BX
;   Corrupts registers:
;       AX, DX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
FlashSst_WithFlashvarsInDSBX:
    push    ds
    push    es
    push    bx
    push    cx
    push    si
    push    bp
    mov     bp, bx                  ; Flashvars now in SS:BP.

    mov     BYTE [bp+FLASHVARS.flashResult], FLASH_RESULT.DeviceNotDetected
    call    DetectSstDevice
    jc      SHORT .ExitOnError

    call    CalibrateSstTimeout
    
    mov     BYTE [bp+FLASHVARS.flashResult], FLASH_RESULT.PollingTimeoutError
    mov     cx, [bp+FLASHVARS.wPagesToFlash]
    lds     si, [bp+FLASHVARS.fpNextSourcePage]
    les     di, [bp+FLASHVARS.fpNextDestinationPage]
%ifdef CLD_NEEDED
    cld
%endif

ALIGN JUMP_ALIGN
.NextPage:
    ; See if this page needs updating.
    push    si
    push    di
    push    cx
    mov     cx, [bp+FLASHVARS.wEepromPageSize]
    mov     bx, cx
    repe cmpsb
    pop     cx
    pop     di
    pop     si
    jnz     SHORT .FlashThisPage
    add     si, bx
    add     di, bx
    jmp     SHORT .ContinueLoop

.FlashThisPage:
    call    EraseSstPage
    jc      SHORT .ExitOnError
    call    WriteSstPage
    jc      SHORT .ExitOnError
.ContinueLoop:
    loop    .NextPage

    ; The write process has already confirmed the results one byte at a time.
    ; Here we do an additional verify check just in case there was some 
    ; kind of oddity with pages / addresses.
    mov     BYTE [bp+FLASHVARS.flashResult], FLASH_RESULT.DataVerifyError
    mov     ax, [bp+FLASHVARS.wPagesToFlash]
    mov     cl, SST_PAGE_SIZE_SHIFT
    shl     ax, cl
    mov     cx, ax
    lds     si, [bp+FLASHVARS.fpNextSourcePage]
    les     di, [bp+FLASHVARS.fpNextDestinationPage]
    repe cmpsb
    jnz     SHORT .ExitOnError

%ifndef CHECK_FOR_UNUSED_ENTRYPOINTS
%if FLASH_RESULT.success = 0    ; Just in case this should ever change
    mov     [bp+FLASHVARS.flashResult], cl
%else
    mov     BYTE [bp+FLASHVARS.flashResult], FLASH_RESULT.success
%endif
%endif
ALIGN JUMP_ALIGN
.ExitOnError:
    pop     bp
    pop     si
    pop     cx
    pop     bx
    pop     es
    pop     ds
    ret

;--------------------------------------------------------------------
; DetectSstDevice
;   Parameters:
;       SS:BP:  Ptr to FLASHVARS
;   Returns:
;       CF: Clear if supported SST device found
;           Set if supported SST device not found
;   Corrupts registers:
;       AX, DI, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DetectSstDevice:
    les     di, [bp+FLASHVARS.fpNextDestinationPage]

    cli
    mov     BYTE [es:05555h], 0AAh  ; Enter software ID sequence.
    mov     BYTE [es:02AAAh], 055h
    mov     BYTE [es:05555h], 090h
    mov     al, [es:di]             ; Extra reads to be sure device
    mov     al, [es:di]             ; has time to respond.
    mov     al, [es:di]
    mov     ah, [es:di]             ; Vendor ID in AH.
    mov     al, [es:di + 1]         ; Device ID in AL.
    mov     BYTE [es:05555h], 0F0h  ; Exit software ID.
    sti

    cmp     al, 0B4h
    jb      SHORT .NotValidDevice
    cmp     al, 0B7h
    ja      SHORT .NotValidDevice
    cmp     ah, 0BFh
    jne     SHORT .NotValidDevice
    ret

.NotValidDevice:
    stc
    ret
    
;--------------------------------------------------------------------
; CalibrateSstTimeout
;   Parameters:
;       SS:BP:  Ptr to FLASHVARS
;   Returns:
;       FLASHVARS.wTimeoutCounter
;   Corrupts registers:
;       AX, BX, CX, SI, DI, DS, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CalibrateSstTimeout:
    LOAD_BDA_SEGMENT_TO ds, ax
    les     di, [bp+FLASHVARS.fpNextDestinationPage]
    xor     cx, cx
    mov     si, cx
    mov     di, cx
    mov     al, [es:di]
    not     al                          ; Forces poll to fail.

    mov     bx, [BDA.dwTimerTicks]      ; Read low word only.
    inc     bx
.WaitForFirstIncrement:
    cmp     bx, [BDA.dwTimerTicks]
    jnz     SHORT .WaitForFirstIncrement

    inc     bx

.WaitForSecondIncrement:
    inc     ch                          ; cx now 0x0100
.PollLoop:                              ; Identical to poll loop used 
    cmp     [es:di], al                 ; during programming
    jz      SHORT .PollComplete         ; Will never branch in this case
    loop    .PollLoop
.PollComplete:
    add     si, 1                       ; number of poll loops completed
    jc      SHORT .countOverflow
    cmp     bx, [BDA.dwTimerTicks]
    jnz     SHORT .WaitForSecondIncrement

.CalComplete:
    ; SI ~= number of polling loops in 215us.
    mov     [bp+FLASHVARS.wTimeoutCounter], si
    ret
        
.countOverflow:
    ; Clamp on overflow, although it should not be possible on
    ; real hardware. In principle SI could overflow on a very
    ; fast CPU. However the SST device is on a slow bus. Even
    ; running at the min read cycle time of fastest version of
    ; the device, SI can not overflow.
    dec     si
    jmp     SHORT .CalComplete

;--------------------------------------------------------------------
; EraseSstPage
;   Parameters:
;       ES:DI:  Destination ptr.
;   Returns:
;       CF:     Set on error.
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
EraseSstPage:
    push    cx

    mov     BYTE [es:05555h], 0AAh  ; Sector erase sequence.
    mov     BYTE [es:02AAAh], 055h
    mov     BYTE [es:05555h], 080h
    mov     BYTE [es:05555h], 0AAh
    mov     BYTE [es:02AAAh], 055h
    mov     BYTE [es:di], 030h

    mov     ax, 1163                ; 1163 x ~215us = 250ms = 10x datasheet max
.TimeoutOuterLoop:
    mov     cx, [bp+FLASHVARS.wTimeoutCounter]
.TimeoutInnerLoop:
    cmp     BYTE [es:di], 0FFh      ; Will return 0FFh when erase complete.
    jz      SHORT .Exit
    loop    .TimeoutInnerLoop
    dec     ax
    jnz     SHORT .TimeoutOuterLoop
    stc                             ; Timed out.
.Exit:
    pop     cx
    ret

;--------------------------------------------------------------------
; WriteSstPage
;   Parameters:
;       DS:SI:  Source ptr.
;       ES:DI:  Destination ptr.
;   Returns:
;       SI, DI: Each advanced forward 1 page.
;       CF:     Set on error.
;   Corrupts registers:
;       AL, BX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
WriteSstPage:
    push    cx

    mov     bx, [bp+FLASHVARS.wTimeoutCounter]
    mov     dx, [bp+FLASHVARS.wEepromPageSize]
    cli

.NextByte:
    lodsb
    mov     BYTE [es:05555h], 0AAh  ; Byte program sequence.
    mov     BYTE [es:02AAAh], 055h
    mov     BYTE [es:05555h], 0A0h
    mov     [es:di], al

    mov     cx, bx
.WaitLoop:
    cmp     [es:di], al             ; Device won't return actual data until 
    jz      SHORT .ByteFinished     ; write complete. Timeout ~215us, or 
    loop    .WaitLoop               ; ~10x 20us max program time from datasheet.

    stc                             ; Write timeout.
    jmp     SHORT .Exit

.ByteFinished:
    inc     di
    dec     dx
    jnz     SHORT .NextByte
    clc
.Exit:
    sti
    pop     cx
    ret