source: vbox/trunk/src/VBox/Devices/PC/BIOS/apm_pm.asm@ 100658

; $Id:
;; @file
; Protected-mode APM implementation.
;

;
; Copyright (C) 2006-2023 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; 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, in version 3 of the
; License.
;
; 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.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; SPDX-License-Identifier: GPL-3.0-only
;


include commondefs.inc

;; 16-bit protected mode APM entry point

_TEXT           segment public 'CODE'

extern          _apm_function:near      ; implemented in C code


public          apm_pm16_entry

;
; This module is for protected mode only and therefore
; 286+ only
;
SET_DEFAULT_CPU_286


; APM function dispatch table
apm_disp:
                dw      offset apmf_disconnect  ; 04h
                dw      offset apmf_idle        ; 05h
                dw      offset apmf_busy        ; 06h
                dw      offset apmf_set_state   ; 07h
                dw      offset apmf_enable      ; 08h
                dw      offset apmf_restore     ; 09h
                dw      offset apmf_get_status  ; 0Ah
                dw      offset apmf_get_event   ; 0Bh
                dw      offset apmf_pwr_state   ; 0Ch
                dw      offset apmf_dev_pm      ; 0Dh
                dw      offset apmf_version     ; 0Eh
                dw      offset apmf_engage      ; 0Fh
                dw      offset apmf_get_caps    ; 10h
apm_disp_end:

;
; APM worker routine. Function code in AL; it is assumed that AL >= 4.
; Caller must preserve BP.
;
apm_worker      proc    near

                sti                     ; TODO ?? necessary ??

                push    ax              ; check if function is supported...
                xor     ah, ah
                sub     al, 4
                mov     bp, ax
                shl     bp, 1
                cmp     al, (apm_disp_end - apm_disp) / 2
                pop     ax
                mov     ah, 53h         ; put back APM function
                jae     apmw_bad_func   ; validate function range

                jmp     apm_disp[bp]    ; and dispatch

apmf_disconnect:                        ; function 04h
                jmp     apmw_success

apmf_idle:                              ; function 05h
if 1
                ; Port I/O based HLT equivalent using a custom BIOS I/O port.
                ; Works in situations where HLT can't be used, such as Windows 3.1
                ; in Standard mode or DR-DOS 5.0/6.0 EMM386.SYS.
                push    si
                push    cx
                push    dx

                mov     dx, 40Fh
                mov     si, offset hlt_string
                mov     cx,8
                rep outsb

                pop     dx
                pop     cx
                pop     si

                jmp     apmw_success

hlt_string      db      'Prochalt'

else
                ;
                ; Windows 3.1 POWER.DRV in Standard mode calls into APM
                ; with CPL=3. If that happens, the HLT instruction will fault
                ; and Windows will crash. To prevent that, we check the CPL
                ; and do nothing (better than crashing).
                ;
                push    cs
                pop     ax
                test    ax, 3           ; CPL > 0?
                jnz     apmw_success
                sti
                hlt
                jmp     apmw_success
endif

apmf_busy:                              ; function 06h
;               jmp     apmw_success

apmf_set_state:                         ; function 07h
;               jmp     apmw_success

apmf_enable:                            ; function 08h
                jmp     apmw_success

apmf_restore:                           ; function 09h
;               jmp     apmw_success

apmf_get_status:                        ; function 0Ah
                jmp     apmw_bad_func

apmf_get_event:                         ; function 0Bh
                mov     ah, 80h
                jmp     apmw_failure

apmf_pwr_state:                         ; function 0Ch

apmf_dev_pm:                            ; function 0Dh
                jmp     apmw_bad_func

apmf_version:                           ; function 0Eh
                mov     ax, 0102h
                jmp     apmw_success

apmf_engage:                            ; function 0Fh
                ; TODO do something?
                jmp     apmw_success

apmf_get_caps:                          ; function 10h
                mov     bl, 0           ; no batteries
                mov     cx, 0           ; no special caps
                jmp     apmw_success

apmw_success:
                clc                     ; successful return
                ret

apmw_bad_func:
                mov     ah, 09h         ; unrecognized device ID - generic

apmw_failure:
                stc                     ; error for unsupported functions
                ret

apm_worker      endp


;; 16-bit protected mode APM entry point

;; According to the APM spec, only CS (16-bit code selector) is defined.
;; The data selector can be derived from it.

apm_pm16_entry:

                mov     ah, 2           ; mark as originating in 16-bit PM

                                        ; fall through

apm_pm16_entry_from_32:

                push    ds              ; save registers
                push    bp

                push    cs
                pop     bp
                add     bp, 8           ; calculate data selector
                mov     ds, bp          ; load data segment

                call    apm_worker      ; call APM handler

                pop     bp
                pop     ds              ; restore registers

                retf                    ; return to caller - 16-bit return
                                        ; even to 32-bit thunk!

_TEXT           ends


if VBOX_BIOS_CPU ge 80386

.386

BIOS32          segment public 'CODE' use32

public          apm_pm32_entry

;; 32-bit protected mode APM entry point and thunk

;; According to the APM spec, only CS (32-bit) is defined. 16-bit code
;; selector and the data selector can be derived from it.

;; WARNING: To simplify matters, we use 16-bit far return to go from 32-bit
;; code to 16-bit and back. As a consequence, the 32-bit APM code must lie
;; below 64K boundary in the 32-bit APM code segment.

apm_pm32_entry:

                push    ebp             ; ebp is not used by APM

                mov     bp, cs          ; return address for 16-bit code
                push    bp
                mov     ebp, apm_pm32_back
                push    bp              ; Note: 16:16 address!

                push    cs
                pop     ebp
                add     ebp, 8          ; calculate 16-bit code selector
                push    bp              ; push 16-bit code selector

                mov     ebp, apm_pm16_entry_from_32
                push    bp              ; push 16-bit offset

                mov     ah, 3           ; mark as originating in 32-bit PM

                db      66h             ; force a 16-bit return
                retf                    ; off to 16-bit code...

apm_pm32_back:                          ; return here from 16-bit code

                pop     ebp             ; restore scratch register
                retf

BIOS32          ends

endif           ; 32-bit code

                end