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acpi_timer.c revision 1.18 
      1 /* $NetBSD: acpi_timer.c,v 1.18 2010/07/10 19:37:38 jruoho 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 1.18 2010/07/10 19:37:38 jruoho 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 
     44 static struct timecounter acpi_timecounter = {
     45 	acpitimer_read_safe,
     46 	0,
     47 	0x00ffffff,
     48 	PM_TIMER_FREQUENCY,
     49 	"ACPI-Safe",
     50 	900,
     51 	NULL,
     52 	NULL,
     53 };
     54 
     55 int
     56 acpitimer_init(struct acpi_softc *sc)
     57 {
     58 	ACPI_STATUS res;
     59 	uint32_t bits;
     60 	int i, j;
     61 
     62 	res = AcpiGetTimerResolution(&bits);
     63 
     64 	if (res != AE_OK)
     65 		return -1;
     66 
     67 	if (bits == 32)
     68 		acpi_timecounter.tc_counter_mask = 0xffffffff;
     69 
     70 	for (i = j = 0; i < 10; i++)
     71 		j += acpitimer_test();
     72 
     73 	if (j >= 10) {
     74 		acpi_timecounter.tc_name = "ACPI-Fast";
     75 		acpi_timecounter.tc_get_timecount = acpitimer_read_fast;
     76 		acpi_timecounter.tc_quality = 1000;
     77 	}
     78 
     79 	tc_init(&acpi_timecounter);
     80 
     81 	aprint_debug_dev(sc->sc_dev,
     82 	    "%s %d-bit timer\n", acpi_timecounter.tc_name, bits);
     83 
     84 	return 0;
     85 }
     86 
     87 int
     88 acpitimer_detach(void)
     89 {
     90 
     91 	return tc_detach(&acpi_timecounter);
     92 }
     93 
     94 u_int
     95 acpitimer_read_fast(struct timecounter *tc)
     96 {
     97 	uint32_t t;
     98 
     99 	(void)AcpiGetTimer(&t);
    100 
    101 	return t;
    102 }
    103 
    104 /*
    105  * Some chipsets (PIIX4 variants) do not latch correctly;
    106  * there is a chance that a transition is hit.
    107  */
    108 u_int
    109 acpitimer_read_safe(struct timecounter *tc)
    110 {
    111 	uint32_t t1, t2, t3;
    112 
    113 	(void)AcpiGetTimer(&t2);
    114 	(void)AcpiGetTimer(&t3);
    115 
    116 	do {
    117 		t1 = t2;
    118 		t2 = t3;
    119 
    120 		(void)AcpiGetTimer(&t3);
    121 
    122 	} while ((t1 > t2) || (t2 > t3));
    123 
    124 	return t2;
    125 }
    126 
    127 uint32_t
    128 acpitimer_delta(uint32_t end, uint32_t start)
    129 {
    130 	const u_int mask = acpi_timecounter.tc_counter_mask;
    131 	uint32_t delta;
    132 
    133 	if (end >= start)
    134 		delta = end - start;
    135 	else
    136 		delta = ((mask - start) + end + 1) & mask;
    137 
    138 	return delta;
    139 }
    140 
    141 #define N 2000
    142 
    143 static int
    144 acpitimer_test(void)
    145 {
    146 	uint32_t last, this, delta;
    147 	int minl, maxl, n;
    148 
    149 	minl = 10000000;
    150 	maxl = 0;
    151 
    152 	acpi_md_OsDisableInterrupt();
    153 
    154 	(void)AcpiGetTimer(&last);
    155 
    156 	for (n = 0; n < N; n++) {
    157 
    158 		(void)AcpiGetTimer(&this);
    159 
    160 		delta = acpitimer_delta(this, last);
    161 
    162 		if (delta > maxl)
    163 			maxl = delta;
    164 		else if (delta < minl)
    165 			minl = delta;
    166 
    167 		last = this;
    168 	}
    169 
    170 	acpi_md_OsEnableInterrupt();
    171 
    172 	if (maxl - minl > 2 )
    173 		n = 0;
    174 	else if (minl < 0 || maxl == 0)
    175 		n = 0;
    176 	else
    177 		n = 1;
    178 
    179 	return n;
    180 }
    181