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acpi_timer.c revision 1.14.2.1 
      1 /* $NetBSD: acpi_timer.c,v 1.14.2.1 2010/04/30 14:43:06 uebayasi Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2006 Matthias Drochner <drochner (at) NetBSD.org>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.14.2.1 2010/04/30 14:43:06 uebayasi Exp $");
     31 
     32 #include <sys/types.h>
     33 #include <sys/systm.h>
     34 #include <sys/time.h>
     35 #include <sys/timetc.h>
     36 
     37 #include <dev/acpi/acpivar.h>
     38 #include <dev/acpi/acpi_timer.h>
     39 
     40 #include <machine/acpi_machdep.h>
     41 
     42 static int acpitimer_test(void);
     43 static uint32_t acpitimer_delta(uint32_t, uint32_t);
     44 static u_int acpitimer_read_safe(struct timecounter *);
     45 static u_int acpitimer_read_fast(struct timecounter *);
     46 
     47 static struct timecounter acpi_timecounter = {
     48 	acpitimer_read_safe,
     49 	0,
     50 	0x00ffffff,
     51 	PM_TIMER_FREQUENCY,
     52 	"ACPI-Safe",
     53 	900,
     54 	NULL,
     55 	NULL,
     56 };
     57 
     58 int
     59 acpitimer_init(void)
     60 {
     61 	uint32_t bits;
     62 	int i, j;
     63 	ACPI_STATUS res;
     64 
     65 	res = AcpiGetTimerResolution(&bits);
     66 	if (res != AE_OK)
     67 		return (-1);
     68 
     69 	if (bits == 32)
     70 		acpi_timecounter.tc_counter_mask = 0xffffffff;
     71 
     72 	j = 0;
     73 	for (i = 0; i < 10; i++)
     74 		j += acpitimer_test();
     75 
     76 	if (j >= 10) {
     77 		acpi_timecounter.tc_name = "ACPI-Fast";
     78 		acpi_timecounter.tc_get_timecount = acpitimer_read_fast;
     79 		acpi_timecounter.tc_quality = 1000;
     80 	}
     81 
     82 	tc_init(&acpi_timecounter);
     83 	aprint_verbose("%s %d-bit timer\n", acpi_timecounter.tc_name, bits);
     84 
     85 	return (0);
     86 }
     87 
     88 int
     89 acpitimer_detach(void)
     90 {
     91 	return tc_detach(&acpi_timecounter);
     92 }
     93 
     94 static u_int
     95 acpitimer_read_fast(struct timecounter *tc)
     96 {
     97 	uint32_t t;
     98 
     99 	AcpiGetTimer(&t);
    100 	return (t);
    101 }
    102 
    103 /*
    104  * Some chipsets (PIIX4 variants) do not latch correctly; there
    105  * is a chance that a transition is hit.
    106  */
    107 static u_int
    108 acpitimer_read_safe(struct timecounter *tc)
    109 {
    110 	uint32_t t1, t2, t3;
    111 
    112 	AcpiGetTimer(&t2);
    113 	AcpiGetTimer(&t3);
    114 	do {
    115 		t1 = t2;
    116 		t2 = t3;
    117 		AcpiGetTimer(&t3);
    118 	} while ((t1 > t2) || (t2 > t3));
    119 	return (t2);
    120 }
    121 
    122 static uint32_t
    123 acpitimer_delta(uint32_t end, uint32_t start)
    124 {
    125 	uint32_t delta;
    126 	u_int mask = acpi_timecounter.tc_counter_mask;
    127 
    128 	if (end >= start)
    129 		delta = end - start;
    130 	else
    131 		delta = ((mask - start) + end + 1) & mask;
    132 
    133 	return (delta);
    134 }
    135 
    136 #define N 2000
    137 static int
    138 acpitimer_test(void)
    139 {
    140 	uint32_t last, this, delta;
    141 	int minl, maxl, n;
    142 
    143 	minl = 10000000;
    144 	maxl = 0;
    145 
    146 	acpi_md_OsDisableInterrupt();
    147 	AcpiGetTimer(&last);
    148 	for (n = 0; n < N; n++) {
    149 		AcpiGetTimer(&this);
    150 		delta = acpitimer_delta(this, last);
    151 		if (delta > maxl)
    152 			maxl = delta;
    153 		else if (delta < minl)
    154 			minl = delta;
    155 		last = this;
    156 	}
    157 	acpi_md_OsEnableInterrupt();
    158 
    159 	if (maxl - minl > 2 )
    160 		n = 0;
    161 	else if (minl < 0 || maxl == 0)
    162 		n = 0;
    163 	else
    164 		n = 1;
    165 
    166 	return (n);
    167 }
    168