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acpi_timer.c revision 1.24 
      1 /* $NetBSD: acpi_timer.c,v 1.24 2018/10/16 00:30:08 jmcneill 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 1.24 2018/10/16 00:30:08 jmcneill 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 #if !defined(ACPI_REDUCED_HARDWARE)
     43 static int	acpitimer_test(void);
     44 
     45 static struct timecounter acpi_timecounter = {
     46 	acpitimer_read_safe,
     47 	0,
     48 	0x00ffffff,
     49 	ACPI_PM_TIMER_FREQUENCY,
     50 	"ACPI-Safe",
     51 	900,
     52 	NULL,
     53 	NULL,
     54 };
     55 
     56 static bool
     57 acpitimer_supported(void)
     58 {
     59 	return AcpiGbl_FADT.PmTimerLength != 0;
     60 }
     61 #endif
     62 
     63 int
     64 acpitimer_init(struct acpi_softc *sc)
     65 {
     66 #if !defined(ACPI_REDUCED_HARDWARE)
     67 	ACPI_STATUS rv;
     68 	uint32_t bits;
     69 	int i, j;
     70 
     71 	if (!acpitimer_supported())
     72 		return -1;
     73 
     74 	rv = AcpiGetTimerResolution(&bits);
     75 
     76 	if (ACPI_FAILURE(rv))
     77 		return -1;
     78 
     79 	if (bits == 32)
     80 		acpi_timecounter.tc_counter_mask = 0xffffffff;
     81 
     82 	for (i = j = 0; i < 10; i++)
     83 		j += acpitimer_test();
     84 
     85 	if (j >= 10) {
     86 		acpi_timecounter.tc_name = "ACPI-Fast";
     87 		acpi_timecounter.tc_get_timecount = acpitimer_read_fast;
     88 		acpi_timecounter.tc_quality = 1000;
     89 	}
     90 
     91 	tc_init(&acpi_timecounter);
     92 
     93 	aprint_debug_dev(sc->sc_dev, "%s %d-bit timer\n",
     94 	    acpi_timecounter.tc_name, bits);
     95 
     96 	return 0;
     97 #else
     98 	return -1;
     99 #endif
    100 }
    101 
    102 int
    103 acpitimer_detach(void)
    104 {
    105 #if !defined(ACPI_REDUCED_HARDWARE)
    106 	if (!acpitimer_supported())
    107 		return -1;
    108 
    109 	return tc_detach(&acpi_timecounter);
    110 #else
    111 	return -1;
    112 #endif
    113 }
    114 
    115 #if !defined(ACPI_REDUCED_HARDWARE)
    116 u_int
    117 acpitimer_read_fast(struct timecounter *tc)
    118 {
    119 	uint32_t t;
    120 
    121 	(void)AcpiGetTimer(&t);
    122 
    123 	return t;
    124 }
    125 
    126 /*
    127  * Some chipsets (PIIX4 variants) do not latch correctly;
    128  * there is a chance that a transition is hit.
    129  */
    130 u_int
    131 acpitimer_read_safe(struct timecounter *tc)
    132 {
    133 	uint32_t t1, t2, t3;
    134 
    135 	(void)AcpiGetTimer(&t2);
    136 	(void)AcpiGetTimer(&t3);
    137 
    138 	do {
    139 		t1 = t2;
    140 		t2 = t3;
    141 
    142 		(void)AcpiGetTimer(&t3);
    143 
    144 	} while ((t1 > t2) || (t2 > t3));
    145 
    146 	return t2;
    147 }
    148 
    149 uint32_t
    150 acpitimer_delta(uint32_t end, uint32_t start)
    151 {
    152 	const u_int mask = acpi_timecounter.tc_counter_mask;
    153 	uint32_t delta;
    154 
    155 	if (end >= start)
    156 		delta = end - start;
    157 	else
    158 		delta = ((mask - start) + end + 1) & mask;
    159 
    160 	return delta;
    161 }
    162 
    163 #define N 2000
    164 
    165 static int
    166 acpitimer_test(void)
    167 {
    168 	uint32_t last, this, delta;
    169 	int minl, maxl, n;
    170 
    171 	minl = 10000000;
    172 	maxl = 0;
    173 
    174 	acpi_md_OsDisableInterrupt();
    175 
    176 	(void)AcpiGetTimer(&last);
    177 
    178 	for (n = 0; n < N; n++) {
    179 
    180 		(void)AcpiGetTimer(&this);
    181 
    182 		delta = acpitimer_delta(this, last);
    183 
    184 		if (delta > maxl)
    185 			maxl = delta;
    186 		else if (delta < minl)
    187 			minl = delta;
    188 
    189 		last = this;
    190 	}
    191 
    192 	acpi_md_OsEnableInterrupt();
    193 
    194 	if (maxl - minl > 2 )
    195 		n = 0;
    196 	else if (minl < 0 || maxl == 0)
    197 		n = 0;
    198 	else
    199 		n = 1;
    200 
    201 	return n;
    202 }
    203 #endif
    204