133 lines
2.3 KiB
C
133 lines
2.3 KiB
C
/* $NetBSD: acpi_timer.c,v 1.11 2008/05/11 22:16:45 ad Exp $ */
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.11 2008/05/11 22:16:45 ad Exp $");
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#include <sys/types.h>
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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 int acpitimer_test(void);
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static uint32_t acpitimer_delta(uint32_t, uint32_t);
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static u_int acpitimer_read_safe(struct timecounter *);
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static u_int acpitimer_read_fast(struct timecounter *);
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static struct timecounter acpi_timecounter = {
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acpitimer_read_safe,
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0,
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0x00ffffff,
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PM_TIMER_FREQUENCY,
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"ACPI-Safe",
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900,
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NULL,
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NULL,
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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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int i, j;
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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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j = 0;
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for (i = 0; i < 10; i++)
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j += acpitimer_test();
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if (j >= 10) {
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acpi_timecounter.tc_name = "ACPI-Fast";
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acpi_timecounter.tc_get_timecount = acpitimer_read_fast;
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acpi_timecounter.tc_quality = 1000;
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}
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tc_init(&acpi_timecounter);
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aprint_verbose("%s %d-bit timer\n", acpi_timecounter.tc_name, bits);
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return (0);
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}
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static u_int
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acpitimer_read_fast(struct timecounter *tc)
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{
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uint32_t t;
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AcpiGetTimer(&t);
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return (t);
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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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*/
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static u_int
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acpitimer_read_safe(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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static uint32_t
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acpitimer_delta(uint32_t end, uint32_t start)
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{
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uint32_t delta;
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u_int mask = acpi_timecounter.tc_counter_mask;
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if (end >= start)
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delta = end - start;
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else
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delta = ((mask - start) + end + 1) & mask;
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return (delta);
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}
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#define N 2000
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static int
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acpitimer_test()
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{
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uint32_t last, this, delta;
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int minl, maxl, n;
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minl = 10000000;
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maxl = 0;
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x86_disable_intr();
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AcpiGetTimer(&last);
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for (n = 0; n < N; n++) {
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AcpiGetTimer(&this);
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delta = acpitimer_delta(this, last);
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if (delta > maxl)
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maxl = delta;
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else if (delta < minl)
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minl = delta;
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last = this;
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}
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x86_enable_intr();
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if (maxl - minl > 2 )
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n = 0;
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else if (minl < 0 || maxl == 0)
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n = 0;
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else
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n = 1;
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return (n);
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}
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