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/* $Id: bs3-cmn-pit.c $ */
/** @file
* BS3Kit - PIT Setup and Disable code.
*/
/*
* Copyright (C) 2007-2023 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>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "bs3kit-template-header.h"
#include <iprt/asm-amd64-x86.h>
/*********************************************************************************************************************************
* Defined Constants And Macros *
*********************************************************************************************************************************/
#define BS3_PIT_PORT_CMD 0x43
#define BS3_PIT_PORT_CH0_DATA 0x40
#define BS3_PIT_HZ UINT32_C(1193182)
/*********************************************************************************************************************************
* External Symbols *
*********************************************************************************************************************************/
extern FNBS3TRAPHANDLER16 bs3PitIrqHandler_c16;
extern FNBS3TRAPHANDLER32 bs3PitIrqHandler_c32;
extern FNBS3TRAPHANDLER64 bs3PitIrqHandler_c64;
#undef Bs3PitSetupAndEnablePeriodTimer
BS3_CMN_DEF(void, Bs3PitSetupAndEnablePeriodTimer,(uint16_t cHzDesired))
{
RTCCUINTREG fSaved;
uint16_t cCount;
uint16_t cMsInterval;
uint32_t cNsInterval;
/*
* Disable the PIT and make sure we've configured the IRQ handlers.
*/
Bs3PitDisable();
Bs3PicSetup(false /*fForcedReInit*/);
Bs3TrapSetHandlerEx(0x70, bs3PitIrqHandler_c16, bs3PitIrqHandler_c32, bs3PitIrqHandler_c64);
/*
* Reset the counters.
*/
g_cBs3PitNs = 0;
g_cBs3PitMs = 0;
g_cBs3PitTicks = 0;
/*
* Calculate an interval.
*/
if (cHzDesired <= 18)
{
cCount = 0; /* 1193182 / 65536 = 18.206512451171875 Hz */
cHzDesired = 18;
cNsInterval = UINT32_C(54925401); /* 65536 / 1193182 = 0.054925401154224586022920225078823 seconds */
cMsInterval = 55;
}
else
{
cCount = BS3_PIT_HZ / cHzDesired;
cHzDesired = BS3_PIT_HZ / cCount;
/* 1s/1193182 = 0.000 000 838 095 110 38550698887512550474278 */
#if ARCH_BITS == 64
cNsInterval = cCount * UINT64_C(838095110) / 1000000;
#elif ARCH_BITS == 32
cNsInterval = cCount * UINT32_C(8381) / 10;
#else
cNsInterval = cCount * 838;
#endif
if (cCount <= 1194)
cMsInterval = 1; /* Must not be zero! */
else
cMsInterval = cCount / 1194;
}
/*
* Do the reprogramming.
*/
fSaved = ASMIntDisableFlags();
ASMOutU8(BS3_PIT_PORT_CMD,
(0 << 6) /* select: channel 0 */
| (3 << 4) /* access mode: lobyte/hibyte */
| (2 << 1) /* operation: Mode 2 */
| 0 /* binary mode */
);
ASMOutU8(BS3_PIT_PORT_CH0_DATA, (uint8_t)cCount);
ASMOutU8(BS3_PIT_PORT_CH0_DATA, (uint8_t)(cCount >> 8));
g_cBs3PitIntervalNs = cNsInterval;
g_cBs3PitIntervalHz = cHzDesired;
g_cBs3PitIntervalMs = cMsInterval;
Bs3PicUpdateMask(UINT16_C(0xfffe), 0);
ASMSetFlags(fSaved);
}
#undef Bs3PitDisable
BS3_CMN_DEF(void, Bs3PitDisable,(void))
{
if (g_cBs3PitIntervalHz != 0)
{
RTCCUINTREG fSaved = ASMIntDisableFlags();
/*
* Not entirely sure what's the best way to do this, but let's try reprogram
* it to a no-reload mode like 0 and set the count to 1.
*/
g_cBs3PitIntervalMs = 0;
ASMOutU8(BS3_PIT_PORT_CMD,
(0 << 6) /* select: channel 0 */
| (1 << 4) /* access mode: lobyte */
| (0 << 1) /* operation: Mode 0 */
| 0 /* binary mode */
);
ASMOutU8(BS3_PIT_PORT_CH0_DATA, (uint8_t)1);
/*
* Then mask the PIT IRQ on the PIC.
*/
Bs3PicUpdateMask(UINT16_C(0xffff), 1);
ASMSetFlags(fSaved);
}
/*
* Reset the interval values (leave the ticks and elapsed ns/ms values as-is).
*/
g_cBs3PitIntervalNs = 0;
g_cBs3PitIntervalMs = 0;
g_cBs3PitIntervalHz = 0;
}
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