74 lines
1.2 KiB
C
74 lines
1.2 KiB
C
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/* $NetBSD: acpi_timer.c,v 1.1 2006/06/21 17:47:23 drochner Exp $ */
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#include <sys/types.h>
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#ifdef __HAVE_TIMECOUNTER
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#include <sys/systm.h>
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#include <sys/time.h>
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#include <sys/timetc.h>
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#include <dev/acpi/acpica.h>
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#include <dev/acpi/acpi_timer.h>
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static u_int acpitimer_read(struct timecounter *);
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static struct timecounter acpi_timecounter = {
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acpitimer_read,
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0,
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0x00ffffff,
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PM_TIMER_FREQUENCY,
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"ACPI_PM_TMR",
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900
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};
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int
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acpitimer_init()
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{
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uint32_t bits;
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ACPI_STATUS res;
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res = AcpiGetTimerResolution(&bits);
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if (res != AE_OK)
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return (-1);
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if (bits == 32)
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acpi_timecounter.tc_counter_mask = 0xffffffff;
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tc_init(&acpi_timecounter);
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printf("acpitimer: %d bits\n", bits);
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return (0);
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}
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/*
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* Some chipsets (PIIX4 variants) do not latch correctly; there
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* is a chance that a transition is hit.
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* For now, just be conservative. We might detect the situation later
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* (by testing, or chipset quirks).
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*/
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static u_int
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acpitimer_read(struct timecounter *tc)
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{
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uint32_t t1, t2, t3;
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AcpiGetTimer(&t2);
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AcpiGetTimer(&t3);
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do {
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t1 = t2;
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t2 = t3;
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AcpiGetTimer(&t3);
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} while ((t1 > t2) || (t2 > t3));
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return (t2);
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}
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#else
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int
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acpitimer_init()
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{
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return (0);
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}
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#endif
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