165 lines
4 KiB
C
165 lines
4 KiB
C
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/* -*- Mode: C; c-basic-offset: 3 -*-
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*
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* apm.c - Support for the legacy Advanced Power Management (APM) BIOS
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*
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* This file is part of Metalkit, a simple collection of modules for
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* writing software that runs on the bare metal. Get the latest code
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* at http://svn.navi.cx/misc/trunk/metalkit/
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*
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* Copyright (c) 2009 Micah Dowty
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "apm.h"
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#include "bios.h"
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#include "intr.h"
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APMState gAPM;
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/*
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* APM_Init --
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*
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* Probe for APM support. If APM is available, this connects to APM.
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*
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* It would be easier to use the 16-bit real mode interface via
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* Metalkit's BIOS module, but that wouldn't work very well for us
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* because we can't handle interrupts during a real-mode BIOS call.
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* So, any APM_Idle() call would hang!
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*
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* Instead, we need to use 16-bit BIOS calls to bootstrap APM, then
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* we do our real work via the 32-bit APM interface that is present
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* in all APM 1.2 BIOSes.
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*
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* On exit, gAPM will have a valid 'connected' flag, APM version,
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* and flags.
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*/
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fastcall void
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APM_Init()
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{
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APMState *self = &gAPM;
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Regs reg = {};
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/* Real mode "APM Installation Check" call */
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reg.ax = 0x5300;
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reg.bx = 0x0000;
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BIOS_Call(0x15, ®);
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if (reg.bx == SIGNATURE_APM && reg.cf == 0) {
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self->version = reg.ax;
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self->flags = reg.cx;
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} else {
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return;
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}
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/* Real-mode interface connect */
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reg.ax = 0x5303;
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reg.bx = 0x0000;
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BIOS_Call(0x15, ®);
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if (reg.cf != 0) {
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return;
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}
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/* Indicate that we want APM v1.2 */
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reg.ax = 0x530e;
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reg.bx = 0x0000;
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reg.cx = 0x0102;
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BIOS_Call(0x15, ®);
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if (reg.cf != 0) {
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return;
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}
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/* Success! */
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self->connected = TRUE;
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}
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/*
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* APM_Idle --
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*
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* If we're connected to APM, issue a "CPU Idle" call. The BIOS may
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* halt the CPU until the next interrupt and/or slow or stop the
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* CPU clock.
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*
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* If we aren't connected to APM or the APM call is unsuccessful,
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* this issue a CPU HLT instruction.
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*/
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fastcall void
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APM_Idle()
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{
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/*
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* XXX: This doesn't actually work, because BIOS_Call disables
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* interrupts! To get idle calls working, we'll need to use
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* the real 32-bit APM interface.
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*/
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#if 0
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APMState *self = &gAPM;
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if (self->connected) {
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Regs reg = {};
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/* Real mode "CPU Idle" call */
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reg.ax = 0x5305;
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BIOS_Call(0x15, ®);
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if (reg.cf == 0) {
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/* Success */
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return;
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}
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}
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#endif
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/* Fall back to CPU HLT */
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Intr_Halt();
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}
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/*
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* APM_SetPowerState --
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*
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* Set the power state of all APM-managed devices.
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* If we aren't connected to APM, always fails.
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*
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* Returns TRUE on success, FALSE on error.
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*/
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fastcall Bool
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APM_SetPowerState(uint16 state)
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{
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APMState *self = &gAPM;
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if (self->connected) {
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Regs reg = {};
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reg.ax = 0x5307; // APM Set Power State
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reg.bx = 0x0001; // All devices
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reg.cx = state;
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BIOS_Call(0x15, ®);
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return reg.cf == 0;
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}
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return FALSE;
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}
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