title "PCI bus Support Assembley Code"
;++
;
; Copyright (c) 1989 Microsoft Corporation
;
; Module Name:
;
; hwpcia.asm
;
; Abstract:
;
; Calls the PCI rom function to determine what type of PCI
; support is prsent, if any.
;
; Base code provided by Intel
;
; Author:
;
;--
.386p
.xlist
include hwpci.inc
.list
if DBG
extrn _BlPrint:PROC
endif
_DATA SEGMENT PARA USE16 PUBLIC 'DATA'
if DBG
cr equ 11
PciBIOSSig db 'PCI: Scanning for "PCI "', cr, 0
PciBIOSSigNotFound db 'PCI: BIOS "PCI " not found', cr, 0
PciInt db 'PCI: Calling PCI_BIOS_PRESENT', cr, 0
PciIntFailed db 'PCI: PCI_BIOS_PRESENT returned carry', cr, 0
PciIntAhFailed db 'PCI: PCI_BIOS_PRESENT returned bad AH value', cr, 0
PciIDFailed db 'PCI: PCI_BIOS_PRESENT invalid PCI id', cr, 0
PciInt10IdFailed db 'PCI: PCI10_BIOS_PRESENT invalid PCI id', cr, 0
PciFound db 'PCI BUS FOUND', cr, 0
endif
_DATA ends
_TEXT SEGMENT PARA USE16 PUBLIC 'CODE'
ASSUME CS: _TEXT
;++
;
; BOOLEAN
; HwGetPciSystemData (
; PPCI_SYSTEM_DATA PciSystemData
; )
;
; Routine Description:
;
; This function retrieves the PCI System Data
;
; Arguments:
;
; PciSystemData - Supplies a pointer to the structure which will
; receive the PCI System Data.
;
; Return Value:
;
; True - PCI System Detected and System Data valid
; False - PCI System Not Detected
;
;--
SystemInfoPointer equ [bp + 4]
BiosDateFound equ [bp + 6]
public _HwGetPciSystemData
_HwGetPciSystemData proc
push bp ; The following INT 15H destroies
mov bp, sp ; ALL the general registers.
push si
push di
push bx
;
; Set for no PCI buses present
;
mov bx, SystemInfoPointer
mov byte ptr [bx].NoBuses, 0
;
; Is the BIOS date >= 11/01/92? If so, make the int-1a call
;
push ds
cmp byte ptr [BiosDateFound], 0
jnz gpci00
;
; A valid BIOS date was not found, check for "PCI " in bios code.
;
if DBG
push offset PciBIOSSig
call _BlPrint
add sp, 2
endif
mov bx, 0f000h
mov ds, bx
mov bx, 0fffch
spci05: cmp dword ptr ds:[bx], ' ICP' ; 'PCI ' found at this addr?
je short gpci00 ; found
dec bx ; next location
jnz short spci05 ; loop
jmp spci_notfound ; wrapped, all done - not found
gpci00:
pop ds
if DBG
push offset PciInt
call _BlPrint
add sp, 2
endif
;
; Check for a PCI system. Issue the PCI Present request.
;
mov ax, PCI_BIOS_PRESENT ; Real Mode Presence Request
int PCI_INTERFACE_INT ; Just Do It!
jc gpci10 ; Carry Set => No PCI
cmp ah, 0 ; If PCI Present AH == 0
jne gpci12 ; AH != 0 => No PCI
cmp edx, " ICP" ; "PCI" Backwards (with a trailing space)
jne gpci14 ; PCI Signature in EDX => PCI Exists
;
; Found PCI BIOS Version > 1.0
;
; The only thing left to do is squirrel the data away for the caller
;
mov dx, bx ; Save revision level
mov bx, SystemInfoPointer ; Get caller's Pointer
mov byte ptr [bx].MajorRevision, dh
mov byte ptr [bx].MinorRevision, dl
inc cl ; NoBuses = LastBus+1
if 0
;
; Some PIC BIOS returns very large number of NoBuses. As a work-
; around we mask the value to 16, unless the BIOS also return CH as
; neg cl then we believe it.
;
cmp cl, 16
jbe short @f
neg ch
inc ch
cmp cl, ch
je short @f
mov cl, 16
@@:
endif
mov byte ptr [bx].NoBuses, cl
mov byte ptr [bx].HwMechanism, al
jmp Done ; We're done
if DBG
gpci10: mov ax, offset PciIntFailed
jmp short gpci_oldbios
gpci12: mov ax, offset PciIntAhFailed
jmp short gpci_oldbios
gpci14: mov ax, offset PciIDFailed
gpci_oldbios:
push ax
call _BlPrint
add sp, 2
else
gpci10:
gpci12:
gpci14:
endif
;
; Look for BIOS Version 1.0, This has a different function #
;
mov ax, PCI10_BIOS_PRESENT ; Real Mode Presence Request
int PCI_INTERFACE_INT ; Just Do It!
; Version 1.0 has "PCI " in dx and cx, the Version number in ax, and the
; carry flag cleared. These are all the indications available.
;
cmp dx, "CP" ; "PC" Backwards
jne gpci50 ; PCI Signature not in DX & CX => No PCI
cmp cx, " I" ; "I " Backwards
jne gpci50 ; PCI Signature not in EDX => No PCI
;
; Found PCI BIOS Version 1.0
;
; The only thing left to do is squirrel the data away for the caller
;
mov bx, SystemInfoPointer ; Get caller's Pointer
mov byte ptr [bx].MajorRevision, ah
mov byte ptr [bx].MinorRevision, al
;
; The Version 1.0 BIOS is only on early HW that had couldn't support
; Multi Function devices or multiple bus's. So without reading any
; device data, mark it as such.
;
mov byte ptr [bx].HwMechanism, 2
mov byte ptr [bx].NoBuses, 1
jmp Done
spci_notfound:
pop ds ; restore ds
if DBG
push offset PciBIOSSigNotFound
call _BlPrint
add sp, 2
endif
jmp gpci_exit
if DBG
gpci50: push offset PciInt10IdFailed
jmp Done10
Done: push offset PciFound
Done10: call _BlPrint
add sp, 2
else
; non-debug no prints
gpci50:
Done:
endif
gpci_exit:
pop bx
pop di
pop si
pop bp
ret
_HwGetPciSystemData endp
_TEXT ends
end
