;-----------------------------------------------------------

 ;功能: 通过SMbus 读取内存的SPD 信息

 ;时间: 2015/09

 ;环境: DOS + MASM5

 ;说明: 代码中涉及的smbus规范是基于Intel平台

 ;---------------------------------------------------------

 ;功能: 显示ascii 表示的字符

 echoch macro ascii

     mov ah,

     mov dl,ascii

     int 21h

     endm

 ;---------------------------------------------------------

     .386P

 ;-------------------- data segment ---------------------------------

 dseg segment use16

     busnum dw 0000h  ;总线号0 - 00FFh

     devnum dw 001fh  ;设备号0 - 001Fh

     funnum dw 0007h  ;功能号0 - 0007h

     regnum dw 00ffh  ;寄存器0 - 00FFh

     ;

     sm_base   dw 0000h ;存放smbus 基地址

     sm_devnum dw 0000h   ;a0/a2/a4/a6

     sm_regnum dw 0000h   ;

     ;

     bufferlen =

     buffer db bufferlen dup() ;存放spd  128-byte的信息

     buffer1 db 'smbus base address :'

     buffer2 db 'device index :'

 dseg ends

 ;-------------------- data segment end ----------------------------------

 ;-------------------- code segment ---------------------------------

 cseg segment use16

     assume cs:cseg, ds:dseg

 start:

     mov ax,dseg

     mov ds,ax

     ;----------------------扫描PCI ---------------------

     mov busnum,0000h

     mov devnum,0000h

     mov funnum,0000h

     mov regnum,0000h

 nextreg:

     call pci_read     ;读取pci 配置空间的前4 个字节

     cmp ax,0ffffh     ;判断设备是否存在

     jz nextfun        ;不存在，跳到下一个fun

     ;

     add regnum,08h    ;读class code

     call pci_read

     and eax,0ffffff00h

     cmp eax,0c050000h ;根据class code 判断SMbus Controller( 0c0500 )

     jz find           ;是SMbus Controller

 nextfun:

     mov regnum,0000h

     inc funnum

     cmp funnum,0007h

     ja nextdev        ;funnum 大于 7,跳到下一个dev

     jmp nextreg

 nextdev:

     mov regnum,0000h

     mov funnum,0000h

     inc devnum

     cmp devnum,001fh

     ja nextbus      ;devnum 大于 1fh，跳到下一个bus

     jmp nextreg

 nextbus:

     mov regnum,0000h

     mov funnum,0000h

     mov devnum,0000h

     inc busnum

     cmp busnum,0005h

     ja notfind        ;busnum 大于5，没找到SMbus Controller --结束

     jmp nextreg

     ;--------------------找到SMbus  Controller-------------------

 find:

     sub regnum,08h

     add regnum,20h  ;SMbus 的基地址在pci 配置空间中的偏移地址

     call pci_read   ;读取SMbus 的基地址

     and ax,0fffeh   ;1111_1111_1111_1110,最后一位1 :表示端口方式

     mov sm_base,ax  ;把基地址保存到sm_base

     ;

     ;-----------------------打印smbus 的基地址------------

     mov dx,offset buffer1

     mov cx,

     mov ah,40h

     int 21h

     ;

     mov ax,sm_base

     shr ax,

     push ax

     shr al,

     call toascii

     echoch al

     pop ax

     call toascii

     echoch al

     ;

     mov ax,sm_base

     push ax

     shr al,

     call toascii

     echoch al

     pop ax

     call toascii

     echoch al

     echoch 0dh  ;换行

         echoch 0ah

     ;--------------------读smbus  设备的SPD ----------------

     mov sm_devnum,00a0h   ;设备a0

     ;

 nextd:

     mov sm_regnum,0000h

     mov dx,offset buffer2

     mov cx,

     mov ah,40h

     int 21h

     ;

     mov ax,sm_devnum

     push ax

     shr al,

     call toascii

     echoch al

     pop ax

     call toascii

     echoch al

     echoch ' '

     ;

     call sm_read      ;读128-byte 的spd，存入buffer , 并显示buffer

     echoch 0dh        ;换行

         echoch 0ah

         add sm_devnum,   ;设备号a0/a2/a4/a6

         cmp sm_devnum,0a8h

         jl nextd          ;小于，循环

         ;----------------------------------------

     ;--------------结束，返回DOS -------------

 notfind:

     mov ah,4ch

     int 21h

 ;---------------------------------------------

 ;------------------子程序----------------

 ;----------------------------------------

 ;功能: 通过smbus IO registers 读取spd 信息，并存入buffer

 ;入口:

 ;

 sm_read proc

     push dx

     push ax

     ;

     mov ax,dseg           ;设置目的地址(buffer 的地址)

     mov es,ax             ;段地址为数据段地址

     mov di,offset buffer  ;偏移地址为缓冲区的偏移地址

 nextch:

     ;----------smbus 访问规范--------

     call iodelay

     mov dx,sm_base  ;SMbus 的基地址

     add dx,00h      ;status register

     mov al,0feh     ;

     out dx,al

     call iodelay    ;延时

     ;

     mov dx,sm_base

     add dx,04h       ;slave address register

     mov ax,sm_devnum ;从设备地址:a0/a2/a4/a6  ,

     or al,01h        ;末位:1 - 表示读

     out dx,al

     call iodelay

     ;

     mov dx,sm_base

     add dx,03h       ;command register

     mov ax,sm_regnum ;寄存器索引

     out dx,al

     call iodelay

     inc sm_regnum

     ;

     mov dx,sm_base

     add dx,02h       ;control register

     mov al,48h       ;设置读写模式:字节(48h)、字(4ch)、块(54h)

     out dx,al

     call iodelay

     call iodelay

     ;

     mov dx,sm_base

     add dx,00h

     in al,dx

     cmp al,04h       ;判断读结果

     jz enderr        ;读出错,设备不存在,返回

     ;

     mov dx,sm_base

     add dx,05h      ;data0 register

     in al,dx        ;回读数据

     mov es:[di],al  ;数据保存到buffer 中

     inc di

     cmp sm_regnum,7fh

     ja endsm        ;128-byte  读完

     jmp nextch

 endsm:                    ;读完结束，打印buffer 后，结束

     call print_buffer

     pop ax

     pop dx

     ret

 enderr:                 ;读出错结束，直接退出

     pop ax

     pop dx

     ret

 sm_read endp

 ;--------------------------------------------------

 ;功能:延时,等待外设把数据准备好

 ;

 iodelay proc

     push cx

     mov cx,0ffffh

 delay:

     loop delay

     mov cx,0ffffh

 delay1:

     loop delay1

     pop cx

     ret

 iodelay    endp

 ;---------------------------------------------

 ;功能: 根据eax中的地址读取pci的配置空间,并存入eax

 ;入口: busnum、devnum、funnum、regnum

 ;出口: eax

 ;

 pci_read proc

     ;protect register

     push ebx

     push dx

     ;clear

     xor eax,eax

     xor ebx,ebx

     ;enable

     add eax,1h

     shl eax,

     ;bus number

     mov ebx,ds:[]

     and ebx,0ffh

     shl ebx,

     add eax,ebx

     ;device number

     xor ebx,ebx

     mov ebx,ds:[]

     and ebx,0ffh

     shl ebx,

     add eax,ebx

     ;function number

     xor ebx,ebx

     mov ebx,ds:[]

     and ebx,0ffh

     shl ebx,

     add eax,ebx

     ;register

     xor ebx,ebx

     mov ebx,ds:[]

     and ebx,0ffh

     add eax,ebx

     ;read IO

     mov dx,0cf8h

     out dx,eax

     mov dx,0cfch

     in eax,dx

     ;resume register

     pop dx

     pop ebx

     ret

 pci_read endp

 ;----------------------------------------------

 ;功能:打印buffer的内容(以ascii 形式)

 ;

 print_buffer proc

     push ax

     push ds

     push si

     push cx

     push bp

     ;

     mov ax,dseg      ;设置源地址(buffer 的地址)

     mov ds,ax

     mov si,offset buffer

         mov cx,bufferlen

         cld

 nextline3:

     dec cx

         echoch 0dh

         echoch 0ah

         mov bp,

 nextch3:

     lodsb            ;加载一个字节到al

     ;

     push ax

     shr al,

     call toascii

     echoch al

     pop ax

     call toascii

     echoch al

     echoch ' '

     ;

     dec bp

         jz nextline3

     loop nextch3

     ;

     pop bp     ;出栈顺序与入栈顺序相反

     pop cx

     pop si

     pop ds

     pop ax

     ret

 print_buffer endp

 ;----------------------------------------

 ;功能:把al 的低4位转成ascii码,并存入al

 ;入口: al

 ;出口: al

 toascii proc

     and al,0fh  ;高四位清零

     add al,90h  ;1001_xxxx

     daa

     adc al,40h

     daa

     ret

 toascii endp

 ;-------------------------------------------

 cseg ends

 ;------------- code segment end --------------------------

     end start