i2c.inc

<BIOS研发技术剖析>书的源代码,包括完整的BIOS汇编语言源程序.

;-----------------------------------------------------------------------;
;                       StrI2CCycle                                     ;
;-----------------------------------------------------------------------;
; I2C Start Cycle                                                       ;
;-----------------------------------------------------------------------;
StrI2CCycle     PROC    PUBLIC
        push	ax
	push	dx

        mov     ah, 02h         ; 2 bits need to program for Start cycle
        mov     dh, 00000001b   ; I2C data
        mov     dl, 00000011b   ; I2C clock
StartCycle:
        push	dx
	mov	al, dh
	and	al, 00000001b
        shl     al, 01h
        and     dl, 00000001b
        or      al, dl

        shl     al, 03h
        pop	dx
        call    CsI2CWrite
        shr     dh, 01h
        shr     dl, 01h
	dec	ah
        jne     StartCycle

        pop	dx
	pop	ax
        ret
StrI2CCycle     ENDP


;-----------------------------------------------------------------------;
;                       StpI2CCycle                                     ;
;-----------------------------------------------------------------------;
; Send stop command to I2C bus.                                         ;
;-----------------------------------------------------------------------;
StpI2CCycle     PROC    PUBLIC
        push	ax
	push	dx

        mov     ah, 02h         ; 2 bits need to program for Stop cycle
        mov     dh, 00000010b   ; I2C data
        mov     dl, 00000011b   ; I2C clock
StopCycle:
        push	dx
	mov	al,dh
	and	al, 00000001b
        shl     al, 01h
        and     dl, 00000001b
        or      al, dl
        shl     al, 03h
        pop	dx
        call    CsI2CWrite
        shr     dh, 01h
        shr     dl, 01h
        dec	ah
        jne     StopCycle

        pop	dx
	pop	ax
        ret
StpI2CCycle     ENDP


;-----------------------------------------------------------------------;
;                       PreStpI2CCycle                                  ;
;-----------------------------------------------------------------------;
; Send stop command to I2C bus for data low pre-1 clk.                  ;
;-----------------------------------------------------------------------;
PreStpI2CCycle  PROC    PUBLIC
        push	ax
	push	dx

        mov     ah, 03h         ; 3 bits need to program for Stop cycle
        mov     dh, 00000100b   ; I2C data
        mov     dl, 00000110b   ; I2C clock
PreStopCycle:
        push	dx
	mov	al, dh
	and	al, 00000001b
        shl     al, 01h
        and     dl, 00000001b
        or      al, dl
        shl     al, 03h
        pop	dx
        call    CsI2CWrite
        shr     dh, 01h
        shr     dl, 01h
	dec	ah
        jne     PreStopCycle

        pop	dx
	pop	ax
        ret
PreStpI2CCycle  ENDP


;-----------------------------------------------------------------------;
;                       CSI2CCmd                                        ;
;-----------------------------------------------------------------------;
; I2C Command cycle and all common R/W.                                 ;
;-----------------------------------------------------------------------;
CSI2CCmd        PROC    PUBLIC
        push	ax
WriteCmd:
	rol	dh, 01h
	mov	al, dh
	and	al, 01h
        shl     al, 01h
	rol	dl, 01h
        adc     al, 00h
        shl     al, 03h
        call    PreCsI2CWrite
        call    CsI2CDummy
	dec	ah
        jne     WriteCmd

	pop	ax
        ret
CSI2CCmd        ENDP


;-----------------------------------------------------------------------;
;                       CSI2CDummy                                      ;
;-----------------------------------------------------------------------;
; Assert I2C clock to low to extend wait cycle.                         ;
;-----------------------------------------------------------------------;
CSI2CDummy      PROC    PUBLIC
        push	ax
	push	cx

        mov     ah, 06dh
        call    read_sio_byte
        and     al, 11110111b           ;I2C bus clock active level low
        call    write_sio_byte

        mov     cx, 07ffh
        call    DelayBase01

	pop	cx
        pop	ax
        ret
CSI2CDummy     ENDP


;-----------------------------------------------------------------------;
;                       CSI2CRead                                       ;
;-----------------------------------------------------------------------;
; I2C Read Cycle.                                                       ;
;-----------------------------------------------------------------------;
CSI2CRead       PROC    PUBLIC
	push	cx
        push	eax
	push	dx

        mov     cl, al                  ; decode PCI / ATM space

        mov     eax, 8000086ch
        mov     dx, 0cf8h
        out     dx, eax
	jmp	short $+2
        mov     dl, 0fdh
        in      al, dx
        and     al, 11100111b           ; pull data , clock to high
        mov     ah, al
        or      al, 00010000b
        out     dx, al

        mov     cx, 04ffh
        call    DelayBase

        mov     al, ah
        or      al, 00011000b
        out     dx, al

        mov     cx, 07ffh
        call    DelayBase

        in      al, dx
	jmp	short $+2
	mov	cl,al

	pop	dx
	pop	eax
	mov	al,cl
	pop	cx
        ret
CSI2CRead       ENDP


;-----------------------------------------------------------------------;
;                       CSI2CWrite                                      ;
;-----------------------------------------------------------------------;
; I2C Write Cycle.                                                      ;
;-----------------------------------------------------------------------;
CSI2CWrite      PROC    PUBLIC
        push	eax
	push	cx
	push	dx

        mov	cl,al

        mov     eax, 8000086ch
        mov     dx, 0cf8h
        out     dx, eax
	jmp	short $+2
        mov     dl, 0fdh
        in      al, dx
        and     al, 11100111b
        or      al, cl
        out     dx, al

        mov     cx, 0954h
        call    DelayBase01

        pop	dx
	pop	cx
	pop	eax
        ret
CSI2CWrite       ENDP


;-----------------------------------------------------------------------;
;                       PreCSI2CWrite                                   ;
;-----------------------------------------------------------------------;
; I2C Write Cycle for delay clock.                                      ;
; Input : (AL)                                                          ;
; Output:                                                               ;
; Register destroyed: None                                              ;
;-----------------------------------------------------------------------;
PreCSI2CWrite   PROC    PUBLIC
        push	eax
	push	cx
	push	dx

        mov     cl, al

        mov     eax, 8000086ch
        mov     dx, 0cf8h
        out     dx, eax
	jmp	short $+2
        mov     dl, 0fdh
        in      al, dx
        and     al, 11100111b
        or      al, cl
        mov     ah, al
        and     al, 11110111b
        out     dx, al

        mov     cx, 05ffh
        call    DelayBase01

        mov     al, ah
        out     dx, al

        mov     cx, 07ffh
        call    DelayBase01

        pop	dx
	pop	cx
	pop	eax
        ret
PreCSI2CWrite    ENDP


;-----------------------------------------------------------------------;
;                       RvDvAcktoTm                                     ;
;-----------------------------------------------------------------------;
; Receiver send ACK to Transmitter.                                     ;
;-----------------------------------------------------------------------;
RvDvAcktoTm     PROC    PUBLIC
        push	ax
	push	cx
;	push	dx

;        mov     dh, 00000001b   ; I2C data , this is for Receiver ACK cycle
;        mov     dl, 00000001b   ; I2C clock
;        mov     al, 00h
;        or      al, dh
;        shl     al, 01h
;        or      al, dl