reactos/hal/halx86/apic/rtctimer.c

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/*
* PROJECT: ReactOS HAL
* LICENSE: GNU GPL - See COPYING in the top level directory
* FILE: hal/halx86/apic/rtctimer.c
* PURPOSE: HAL APIC Management and Control Code
* PROGRAMMERS: Timo Kreuzer (timo.kreuzer@reactos.org)
* REFERENCES: https://wiki.osdev.org/RTC
* https://forum.osdev.org/viewtopic.php?f=13&t=20825&start=0
* http://www.bioscentral.com/misc/cmosmap.htm
*/
/* INCLUDES *******************************************************************/
#include <hal.h>
#define NDEBUG
#include <debug.h>
/* GLOBALS ********************************************************************/
const UCHAR HalpClockVector = 0xD1;
BOOLEAN HalpClockSetMSRate;
UCHAR HalpNextMSRate;
UCHAR HalpCurrentRate = 9; /* Initial rate 9: 128 Hz / 7.8 ms */
ULONG HalpCurrentTimeIncrement;
static UCHAR RtcMinimumClockRate = 8; /* Minimum rate 8: 256 Hz / 3.9 ms */
static UCHAR RtcMaximumClockRate = 12; /* Maximum rate 12: 16 Hz / 62.5 ms */
/*!
\brief Converts the CMOS RTC rate into the time increment in 100ns intervals.
Rate Freqency Interval (ms) Result
-------------------------------------
0 disabled
1 32768 0.03052 305
2 16384 0.06103 610
3 8192 0.12207 1221
4 4096 0.24414 2441
5 2048 0.48828 4883
6 1024 0.97656 9766
7 512 1.95313 19531
8 256 3.90625 39063
9 128 7.8125 78125
10 64 15.6250 156250
11 32 31.25 312500
12 16 62.5 625000
13 8 125 1250000
14 4 250 2500000
15 2 500 5000000
*/
FORCEINLINE
ULONG
RtcClockRateToIncrement(UCHAR Rate)
{
/* Calculate frequency */
ULONG Freqency = 32768 >> (Rate - 1);
/* Calculate interval in 100ns interval: Interval = (1 / Frequency) * 10000000
This formula will round properly, instead of truncating. */
return (10000000 + (Freqency/2)) / Freqency;
}
VOID
RtcSetClockRate(UCHAR ClockRate)
{
UCHAR RegisterA;
/* Update the global values */
HalpCurrentRate = ClockRate;
HalpCurrentTimeIncrement = RtcClockRateToIncrement(ClockRate);
/* Acquire CMOS lock */
HalpAcquireCmosSpinLock();
// TODO: disable NMI
/* Read value of register A */
RegisterA = HalpReadCmos(RTC_REGISTER_A);
/* Change lower 4 bits to new rate */
RegisterA &= 0xF0;
RegisterA |= ClockRate;
/* Write the new value */
HalpWriteCmos(RTC_REGISTER_A, RegisterA);
/* Release CMOS lock */
HalpReleaseCmosSpinLock();
}
CODE_SEG("INIT")
VOID
NTAPI
HalpInitializeClock(VOID)
{
ULONG_PTR EFlags;
UCHAR RegisterB;
/* Save EFlags and disable interrupts */
EFlags = __readeflags();
_disable();
// TODO: disable NMI
/* Acquire CMOS lock */
HalpAcquireCmosSpinLock();
/* Enable the periodic interrupt in the CMOS */
RegisterB = HalpReadCmos(RTC_REGISTER_B);
HalpWriteCmos(RTC_REGISTER_B, RegisterB | RTC_REG_B_PI);
/* Release CMOS lock */
HalpReleaseCmosSpinLock();
/* Set initial rate */
RtcSetClockRate(HalpCurrentRate);
/* Restore interrupt state */
__writeeflags(EFlags);
/* Notify the kernel about the maximum and minimum increment */
KeSetTimeIncrement(RtcClockRateToIncrement(RtcMaximumClockRate),
RtcClockRateToIncrement(RtcMinimumClockRate));
DPRINT1("Clock initialized\n");
}
VOID
FASTCALL
HalpClockInterruptHandler(IN PKTRAP_FRAME TrapFrame)
{
ULONG LastIncrement;
KIRQL Irql;
/* Enter trap */
KiEnterInterruptTrap(TrapFrame);
#ifdef _M_AMD64
/* This is for debugging */
TrapFrame->ErrorCode = 0xc10c4;
#endif
/* Start the interrupt */
if (!HalBeginSystemInterrupt(CLOCK_LEVEL, HalpClockVector, &Irql))
{
/* Spurious, just end the interrupt */
KiEoiHelper(TrapFrame);
}
/* Read register C, so that the next interrupt can happen */
HalpReadCmos(RTC_REGISTER_C);
/* Save increment */
LastIncrement = HalpCurrentTimeIncrement;
/* Check if someone changed the time rate */
if (HalpClockSetMSRate)
{
/* Set new clock rate */
RtcSetClockRate(HalpNextMSRate);
/* We're done */
HalpClockSetMSRate = FALSE;
}
/* Update the system time -- on x86 the kernel will exit this trap */
KeUpdateSystemTime(TrapFrame, LastIncrement, Irql);
}
VOID
FASTCALL
HalpProfileInterruptHandler(IN PKTRAP_FRAME TrapFrame)
{
__debugbreak();
}
ULONG
NTAPI
HalSetTimeIncrement(IN ULONG Increment)
{
UCHAR Rate;
/* Lookup largest value below given Increment */
for (Rate = RtcMinimumClockRate; Rate <= RtcMaximumClockRate; Rate++)
{
/* Check if this is the largest rate possible */
if (RtcClockRateToIncrement(Rate + 1) > Increment) break;
}
/* Set the rate and tell HAL we want to change it */
HalpNextMSRate = Rate;
HalpClockSetMSRate = TRUE;
/* Return the real increment */
return RtcClockRateToIncrement(Rate);
}